- Utworzony: 06-08-21
- Ostatnie logowanie: 06-08-21
Opis: Still Confused About Masks? Here’s the Science Behind How Face Masks Prevent Coronavirus As states reopen from stay-at-home orders, many, including California, are now requiring people to wear face coverings in most public spaces to reduce the spread of COVID-19. Both the Centers for Disease Control and Prevention (CDC) and the World Health Organization now recommend cloth masks for the general public, but earlier in the pandemic, both organizations recommended just the opposite. These shifting guidelines may have sowed confusion among the public about the utility of masks. But health experts say the evidence is clear that masks can help prevent the spread of COVID-19 and that the more people wearing masks, the better. We talked to UC San Francisco epidemiologist George Rutherford, MD, and infectious disease specialist Peter Chin-Hong, MD, about the CDC’s reversal on mask-wearing, the current science on how masks work, and what to consider when choosing a mask. Why did the CDC change its guidance on wearing masks? The original CDC guidance partly was based on what was thought to be low disease prevalence earlier in the pandemic, said Chin-Hong. “So, of course, you’re preaching that the juice isn’t really worth the squeeze to have the whole population wear masks in the beginning – but that was really a reflection of not having enough testing, anyway,” he said. “We were getting a false sense of security.” Rutherford was more blunt. The legitimate concern that the limited supply of surgical masks and N95 respirators should be saved for health care workers should not have prevented more nuanced messaging about the benefits of masking. “We should have told people to wear cloth masks right off the bat,” he said. Another factor “is that culturally, the U.S. wasn’t really prepared to wear masks,” unlike some countries in Asia where the practice is more common, said Chin-Hong. Even now, some Americans are choosing to ignore CDC guidance and local mandates on masks, a hesitation that Chin-Hong says is “foolhardy.” What may have finally convinced the CDC to change its guidance in favor of masks were rising disease prevalence and a clearer understanding that both pre-symptomatic and asymptomatic transmission are possible – even common. Studies have found that viral load peaks in the days before symptoms begin and that speaking is enough to expel virus-carrying droplets. “I think the biggest thing with COVID now that shapes all of this guidance on masks is that we can’t tell who’s infected,” said Chin-Hong. “You can’t look in a crowd and say, oh, that person should wear mask. There’s a lot of asymptomatic infection, so everybody has to wear a mask.” What evidence do we have that wearing a mask is effective in preventing COVID-19? There are several strands of evidence supporting the efficacy of masks. One category of evidence comes from laboratory studies of respiratory droplets and the ability of various masks to block them. An experiment using high-speed video found that hundreds of droplets ranging from 20 to 500 micrometers were generated when saying a simple phrase, but that nearly all these droplets were blocked when the mouth was covered by a damp washcloth. Another study of people who had influenza or the common cold found that wearing a surgical mask significantly reduced the amount of these respiratory viruses emitted in droplets and aerosols. But the strongest evidence in favor of masks come from studies of real-world scenarios. “The most important thing are the epidemiologic data,” said Rutherford. Because it would be unethical to assign people to not wear a mask during a pandemic, the epidemiological evidence has come from so-called “experiments of nature.” A recent study published in Health Affairs, for example, compared the COVID-19 growth rate before and after mask mandates in 15 states and the District of Columbia. It found that mask mandates led to a slowdown in daily COVID-19 growth rate, which became more apparent over time. The first five days after a mandate, the daily growth rate slowed by 0.9 percentage-points compared to the five days prior to the mandate; at three weeks, the daily growth rate had slowed by 2 percentage-points. Another study looked at coronavirus deaths across 198 countries and found that those with cultural norms or government policies favoring mask-wearing had lower death rates. Two compelling case reports also suggest that masks can prevent transmission in high-risk scenarios, said Chin-Hong and Rutherford. In one case, a man flew from China to Toronto and subsequently tested positive for COVID-19. He had a dry cough and wore a mask on the flight, and all 25 people closest to him on the flight tested negative for COVID-19. In another case, in late May, two hair stylists in Missouri had close contact with 140 clients while sick with COVID-19. Everyone wore a mask and none of the clients tested positive. Do masks protect the people wearing them or the people around them? “I think there’s enough evidence to say that the best benefit is for people who have COVID-19 to protect them from giving COVID-19 to other people, but you’re still going to get a benefit from wearing a mask if you don’t have COVID-19,” said Chin-Hong. Masks may be more effective as a “source control” because they can prevent larger expelled droplets from evaporating into smaller droplets that can travel farther. Another factor to remember, noted Rutherford, is that you could still catch the virus through the membranes in your eyes, a risk that masking does not eliminate. How many people need to wear masks to reduce community transmission? “What you want is 100 percent of people to wear masks, but you’ll settle for 80 percent,” said Rutherford. In one simulation, researchers predicted that 80 percent of the population wearing masks would do more to reduce COVID-19 spread than a strict lockdown. The latest forecast from the Institute of Health Metrics and Evaluation suggests that 33,000 deaths could be avoided by October 1 if 95 percent of people wore masks in public. Even if you live in a community where few people wear masks, you would still reduce your own chances of catching the virus by wearing one, said Chin-Hong and Rutherford. Does the type of mask matter? Studies have compared various mask materials, but for the general public, the most important consideration may be comfort. The best mask is one you can wear comfortably and consistently, said Chin-Hong. KN95 face mask is only necessary in medical situations such as intubation. Surgical masks are generally more protective than disposable mask, and some people find them lighter and more comfortable to wear. The bottom line is that any mask that covers the nose and mouth will be of benefit. “The concept is risk reduction rather than absolute prevention,” said Chin-Hong. “You don’t throw up your hands if you think a mask is not 100 percent effective. That’s silly. Nobody’s taking a cholesterol medicine because they’re going to prevent a heart attack 100 percent of the time, but you’re reducing your risk substantially.” However, both Rutherford and Chin-Hong cautioned against KN95 masks with valves (commonly used in construction to prevent the inhalation of dust) because they do not protect those around you. These one-way valves close when the wearer breathes in, but open when the wearer breathes out, allowing unfiltered air and droplets to escape. Chin-Hong said that anyone wearing a valved mask would need to wear a surgical or cloth mask over it. "Alternatively, just wear a non-valved mask," he said. San Francisco has specified that masks with valves do not comply with the city's face covering order. If we’re practicing social distancing, do we still need to wear masks? A mnemonic that Chin-Hong likes is the “Three W’s to ward off COVID-19:” wearing a mask, washing your hands, and watching your distance. “But of the three, the most important thing is wearing a mask,” he said. Compared to wearing a mask, cleaning your iPhone or wiping down your groceries are “just distractors.” There’s little evidence that fomites (contaminated surfaces) are a major source of transmission, whereas there is a lot of evidence of transmission through inhaled droplets, said Chin-Hong. “You should always wear masks and socially distance,” said Rutherford. “I would be hesitant to try to parse it apart. But, yes, I think mask wearing is more important.”
Data publikacji: 06-08-21
Opis: Do Air Purifiers Actually Work? The promise of an air purifier is an enticing one: An appliance designed to cleanse the air in your home, getting rid of all the impurities including odors, smoke, dust, and pet dander. Given the fact that indoor air can have levels of certain pollutants up to five times higher than outdoor air, we get it. Some models may even be able to target bad air that creeps into your apartment or home, especially if you live in an area affected by pollution, or natural disaster. Most people shouldn't be worried about exposure to temporary pollutants like smoke or exhaust in the air outside your home, as they dissipate over time, explains Ryan Roten, D.O., an emergency medicine doctor with Redlands Community Hospital in California. "In the short term, people will have asthma-like symptoms, primarily, or symptoms closer to allergies or sinusitis, including stuffy nose and a bit of a cough," says Dr. Doten, who has been treating patients with underlying respiratory illnesses as mass wildfires rage along the West Coast and air quality reaches new lows. "If the smoke is dense enough, you might have some headaches due to carbon dioxide, and those with issues like asthma or COPD will have it worse in the moment." Air purifier can indeed neutralize some of the threat posed by air pollution and by indoor activities. In reality, though, not all air purifiers necessarily live up to their marketing hype. How do air purifiers work? Air purifiers usually consist of a filter, or multiple filters, and a fan that sucks in and circulates air. As air moves through the filter, pollutants and particles are captured and the clean air is pushed back out into the living space. Typically, filters are made of paper, fiber (often fiberglass), or mesh, and require regular replacement to maintain efficiency. That means, in addition to the purchase price of an air purifier, you should also factor in operating costs and filter replacement costs. Operational costs can easily amount to $50 annually, since you should be running air purifiers near constantly to garner the benefits. Filter replacements can run upwards of $100 a year all told. How frequently you will have to change filters varies based upon the purifier type and usage. Some filters are reusable and washable, but they require meticulous maintenance, so you don't usually find them on the most effective air purifiers. Reusable filters are generally better at removing larger particles from the air, like dust mites and pollen. You'll also find UV (ultraviolet light) filters on the market, which often claim to destroy biological impurities like mold or bacteria, but many require higher wattage and greater exposure to be effective (not to mention some bacteria is UV-resistant). Other air purifiers use ionizers to help attract particles like static — negative ions bond to dust and allergens and make them settle out of the air. If you're interested in buying desktop air purifier that uses ionizers, make sure it does not produce ozone, a gas made up of three oxygen atoms that is often marketed as helping break down pollutants, because ozone could be a lung irritant and further aggravate asthma conditions. Usually the air purifiers with ozone will have that listed on packaging or in the marketing descriptions. What are air purifiers supposed to filter out — and do they actually do it? Most filters on the market are designed to capture particles like dust and pollen, but don’t catch gases like VOCs (volatile organic compounds) or radon. That would require an adsorbent, like activated carbon. In fact, the Environmental Protection Agency (EPA) warns that the functionality of air purifiers is limited in terms of filtering out gases, and that you must frequently replace filters for optimal functionality, usually about every three or so months. Many air purifiers are good at filtering pollutant particles out of the air (dust, smoke, pollen, etc.), but they are not necessarily very good at removing gaseous pollutants like VOCs or radon from the air that may accumulate from adhesives, paints, or cleaning products. Allergens that are embedded into furniture or flooring are also not captured by them. Additionally, the effectiveness of air purifiers in real-world situations likely won’t mimic those of controlled conditions in a lab (what those "99% effectiveness" claims are referring to!). The location, installation, flow rate, and how long it is operating for will all vary, as will the conditions in the space. In addition, there are other things happening in your home that may effect the efficacy like ventilation (open or closed windows), and new particles are constantly emerging, so the air may not as filtered as the claims may have you believe. Can air purifiers filter the outdoor air that enters your home? Sometimes, non-organic air pollutants — like the VOCs we mentioned previously — can originate from outside your home. "There are all sorts of scenarios in structure fires where large doses of smoke inhalation may lead to cyanide toxicity. But that would largely need to be someone who was standing directly in or near the fire: Those people are brought to emergency rooms immediately," Dr. Roten explains. "Generally, outside pollution or smoke or temporary bad air isn't a constant concern for bystanders." But the right kind of purifier can address any environmental air qualities in your locale. Using nearby wildfires as an example, Dr. Roten adds that a HEPA filter-equipped purifier is your best bet: "Anything that has a true HEPA filter in it is probably adequate enough to filter out most all the large particles that would be concerning," he says. "Most of the smoky smell will also be addressed as well." So… should I buy an air purifier? Before you do, know that air purifiers are not a cure-all. There is very little medical evidence to support that air purifiers directly help improve your health or alleviate allergies and respiratory symptoms. That’s due in part to the fact that it is very difficult to separate the effects of known air-quality pollutants in your home from other environmental and genetic factors. (For instance, how are the furnishings and ventilation in your home affecting you in addition to any indoor pollutants?) But if you are an allergy or asthma sufferer, an air purifier with a HEPA filter may be helpful for you as it will be good at removing fine airborne particles. What is a HEPA filter? HEPA is an acronym for High Efficiency Particulate Air. HEPA filters capture variously sized particles within a multi-layered netting usually made out of very fine fiberglass threads (much thinner than the size of a human hair strand!) with varying sized gaps. The filter is airtight, and comprised of a dense sheet of small fibers pleated and sealed in a metal or plastic frame. The air purifier's fan draws air into the filter and particulates are captured in the filter. The larger particles (ones bigger than the fibers) are captured via impaction (particle crashes into the fiber), mid-sized particles are captured by interception (particle touches the fiber and is captured), and ultra-fine particles are captured by diffusion (while zig-zagging the particle will eventually hit and stick to the fiber). What should I look for in an air purifier? CADR (clean-air delivery rate) rating. This measures the cleaning speed of the purifier for removing smoke, dust, and and pollen. Look for a CADR of at least 300, above 350 is really great. Size guidelines. For proper efficacy, you need a model designed to work in the room size. Choose a model that is designed for an area larger than the one you are outfitting it for if you want to operate it at a lower, quieter setting. AHAM (Association of Home Appliance Manufacturers) Verified mark. AHAM’s standards are design to ensure the safety, efficiency and performance of many home care appliances, including air purifiers. The standards are designed to provide a common understanding between manufacturers and consumers to help make the purchasing process simpler. While voluntary, most reputable air purifiers have undergone this certification program, which often provides a CADR rating and size guidelines. True HEPA. True HEPA filters are effective at removing ultra fine particles (think: dust, dander, pollen, mold and other common allergens in the home). The industry standard for such is that the unit must be able to remove at least 99.97% of particulates measuring 0.3 micron diameter in a lab setting. Remember, it is important to note that in real life settings, the actual efficacy of these devices would be far less as new pollutants are constantly emerging. Note that there is no industry standard for the terms "HEPA-like" or "HEPA-type," and are mostly used as marketing ploys to get consumers to purchase the product. What are other ways I can improve the air quality in my home? The best advice is to address the source of indoor air pollution and ventilate your home. If you are looking to supplement the work of your home air purifiers or see if you can get by without one, we recommended trying these steps to help reduce indoor air irritants: Keep your windows open when it's safe to do so to prevent locking irritants into rooms (especially when air purifiers aren’t running!). Create a stronger cross draft by opening windows on opposite sides of the room if possible. Vacuum often. If you are on the market for a vacuum, opt for one that is sealed, has a bag and is HEPA-certified. They’re better at trapping dust instead of sending it back into the air. The Good Housekeeping Institute recommends the Miele U1 Maverick SHAE0. Regularly change air filters to properly maintain HVAC equipment and maximize effectiveness. Dr. Roten adds that sourcing a HEPA-specific filter for your circulation system can provide additional filtration: "It's recirculate the air in your house a bit better with each pass." Use an exhaust fan in the kitchen (and bath and laundry areas if possible). Switch it on before preheating the oven or firing up the burners, and leave it running for a few minutes after you’re done cooking. Minimize the use of candles or lighting wood fires and ban smoking inside the home. Reducing pollutant sources is a surefire way to improve air quality. Sources of Air Pollution in a Car There are many reasons for poor air quality in a vehicle. Some were mentioned above and here is a list of the most common sources of pollution you may encounter. Odors Cigarette smoke Carbon Monoxide and exhaust fumes from other cars Carbon Dioxide Pet Dander Particulate matter like dust, mold, pollen and bacteria Most of the items in this list are gases (the first four). Gases are difficult to remove with an air purifier since they are incredibly small and require advanced gas filter media. We go into detail in our comprehensive air purifier guide for how to effectively remove them. The pet dander, dust and pollen are airborne particulates and larger than gases. To remove them you need a HEPA air filter as the solutions for gas removal are not effective. Particulate matter is best captured in a net like the fibers of a HEPA filter. Gases in contrast are often adsorbed into a material like activated carbon. So, from an air purifier perspective it depends upon what you need the air cleaner to do before you can identify the best solution. Strategies to Clean the Air There are 3 main strategies to clean the air in any environment. This applies to a home, the office or in a vehicle. Source control – remove the source of the issue. In a car this can be difficult since you don’t have a choice but to drive on the road. Ventilation – this is achieved by circulating air from the outside or by rolling down the windows. Again, this can be difficult depending upon the weather conditions or pollution on the roads. Air Cleaning – using an air filter to remove the pollutants. This list is sorted in the order of importance. So, source control is the first choice, followed by ventilation and then air cleaning. Purpose of Your Car’s Air FilterCars come with an air filter. What is interesting is that the purpose is the same as the air filter in your air conditioning or furnace heating system. And that is to protect the equipment and not your health. In most cases this is a low efficiency pleated filter. This means it will filter out the larger particles only which is most important in maintaining the operation of your vehicle. The same issue exists with your HVAC filter in that the fans are not strong enough to pull air through a higher efficiency filter. So, your car air filter will only remove the biggest pollen or dust particles. And not the finer particles that you breathe into your lungs. Furthermore, imagine if you wanted to remove fumes and emissions from vehicle exhaust. In other words, the gases we listed above. This issue is even harder since a bank of carbon has more air flow resistance and therefore requires a stronger fan to pull the air through. We looked at developing a better filter that could be placed in a car however we determined this was not practical since the fans in a car are just not strong enough. The result would be much lower air flow. This would create a strain on the fan as well as poorer performance in the air conditioning. So, it’s a difficult problem to solve given the limitations. In addition, it takes a good amount of energy to move air through a filter that is effective and there is not a lot of power in a cigarette lighter adaptor. And this leads us to the current car air purifier solutions. How Car Air Purifiers Work For the most part, car air purifiers work on the same principles as a room air purifier although they are much smaller in size. It’s more like a mini or personal air purifier with a limited power source. Here is a listing of the most common technologies. We will examine each in more detail below. Negative ion generator – also referred to as a car air ioniser. HEPA filter Activated Carbon filter Ozone generator Air Freshener Negative Ion Generator The negative ionizer works by emitting a negative charge into the air. There is no filter to catch the particles. This is simply an electronic device and most often is plugged into a cigarette lighter. This car air ionizer requires little power. The concept is that negative ions clean the air of particulates by attaching to the dust, pollen or mold spores and then they are more easily attracted to a surface. However, this does not address the most common issue and that is gas, smoke and odor removal. The only way a negative ioniser could remove any gas is if it creates ozone. This is problematic since ozone is a lung irritant and considered air pollution. We are not meant to breathe in ozone and should avoid it. HEPA Filter A HEPA air filter is the best technology to remove airborne particulates and it does so safely. The problem we have seen with HEPA filters in car air purifiers is that they are much too small to be effective and/or are not true HEPA. As we explain in 5 reasons to buy air purifiers, the bigger the filter is and the higher efficiency it has the better it will do in cleaning the air. You simply cannot cut corners and make a tiny filter or one with a low efficiency. It won’t be able to filter much. Recently, Tesla came out with what they call the Biodefense HEPA filtration system in one of their car models. It seems they did the right thing and built a strong enough fan to power the air through a HEPA filter. The gap that we see with this is that HEPA is not effective for gases. And gases are the primary reason people buy a car air purification system. Gases like car fumes will pass right through the HEPA air filter fibers. For something like cigarette smoke removal, the HEPA air filter will remove the smoke particles but not the smoke odors. Activated Carbon Filter A filter with activated carbon is good in removing many of the gases associated with smoke removal and car fumes. The problem here is that it requires a good amount (more than a pound in a car) as well as a good air flow. The car air purifier we has seen do not have strong enough motors or enough carbon to remove the pollutants. In addition, you simply cannot put a container of active carbon in your car and expect it to clean the air. Furthermore, carbon is not effective for all gases. You often will want additional gas filter media or a treated carbon to have a more complete solution. For HEPA and activated carbon to work you need more power and you don’t have that with the cigarette adaptor or enough space in the car for an air cleaner that is effective. Ozone Generator An ozone generator works as its name implies and that is to create ozone. While ozone can be very effective in gas removal it is terrible to breathe in. And extremely bad if you have a respiratory issue like asthma, COPD or bronchitis. As far as I know car air cleaners are not regulated like room air purifiers for ozone. The only time you would want to use an ozone generator would be in a car when no people are present to remove odors. For example, if you need to remove smoke odors from a car interior, you could use an ozone generator to “shock” the car. Other than that, you should stay away from ozone. Air Freshener An air freshener works by masking odors in a car. It does not remove any odors but rather gives off its own odor so you do not notice the odor you are wanting to avoid. An air freshener introduces gases into your car. It’s not an ideal solution since you breathe in whatever they give off. Do Car Air Purifiers Work? Given what we have described above we have no confidence that a car air purifier will provide the clean air you are looking for. The problems are real, however the solutions simply are not effective. In my opinion, they are quite gimmicky and if they produce ozone you are introducing pollution into your car. This goes against our philosophy of providing products that are effective and safe. So, this is not a product we have any interest in making or selling. However, there is one solution we have seen in military use that could be effective but would require an installation in a vehicle. This is like a whole house or commercial air purification system for a car where you have a separate fan and filter bank. To work effectively you would have to give up some space, say in your trunk as well as go through an installation process. Another solution would be to wear a mask. This will filter out many of the particles however unless you are wearing a respirator with a filter you will likely not be able to filter out the gases. When I am in China and wear a mask, I can still smell the pollution as well as tobacco smoke odors so I know even a N95 mask has limitations.
Data publikacji: 06-08-21
Opis: Details About Rehabilitation Products With a group of experienced foreign trade professionals, we supply rehabilitation products especially for patients and elder people, such as different types of walking sticks, E/M-wheelchiars, E/M hospital beds, walking aids, homecare products like commode chair and shower chair, trekking pole and protectors for outdoor sports, epidemic prevention products like face masks, gloves, thermometers ,protective clothing and first aid kit etc. How do the different types of masks work? Medical masks Also called surgical masks, these are loosefitting disposable masks. They're meant to protect the wearer from contact with droplets and sprays that may contain germs. A medical face mask also filters out large particles in the air when the wearer breathes in. To make medical masks more form-fitting, knot the ear loops where they attach to the mask. Then fold and tuck the unneeded material under the edges. N95 masks An N95 mask is a type of respirator. It offers more protection than a face mask does because it filters out both large and small particles when the wearer inhales. Because N95 masks have been in short supply, the CDC has said they should be reserved for health care providers. Health care providers must be trained and pass a fit test before using an N95 mask. Like surgical masks, N95 masks are intended to be disposable. However, researchers are testing ways to disinfect and reuse them. Some N95 masks, and even some cloth masks, have valves that make them easier to breathe through. Unfortunately, these masks don't filter the air the wearer breathes out. For this reason, they've been banned in some places. Cloth masks A cloth face mask is intended to trap respiratory droplets that are released when the wearer talks, coughs or sneezes. It also acts as a barrier to protect the wearer from inhaling droplets released by others. The most effective cloths masks are made of multiple layers of tightly woven fabric like cotton. A mask with layers will stop more droplets from getting through your mask or escaping from it. Choosing The Right Walking Stick – What To Consider That the walking stick is the right height for you Which hand you are going to hold it in Whether you need the walking stick to stand up by itself How much stability you need it to provide Whether you are going to take it upstairs Whether you need a seat so you can rest If you are looking at a second hand walking stick or inheriting a stick it is important to check the condition. Look to see that the ferrules at the bottom of the stick and any adjustable joins aren’t worn. If it is a wooden walking stick, check that it is long enough and be prepared to cut it down if needed. How To Measure For A Walking Stick Getting the height right for a walking stick is very important. If you have one too high it won’t be as stable and you won’t be able to put weight through it safely. Too low can negatively impact on your posture leading to increased stooping. So Here Is How You Measure For A Walking Stick Wearing your normal shoes, stand-in your normal standing position with your arms relaxed and hanging down by your sides with a slight bend in your elbow. Have someone to hold a stick just close, about 15cm from your side. Your wrist joint should be at the same height as the stick handle without changing your position. If you don’t have a stick to measure against then ask someone to measure from your wrist joint to the floor while you are in this position with a tape measure and round to the nearest cm. How To Use A Walking Stick You can use a walking stick either as a single or as a pair. How you walk with them will depend on what your particular needs are and restrictions you may have. If you are walking with a pair of walking sticks it is particularly important that you walk with the right technique. A physiotherapist can advise you on the right technique for you as well as how to use them going up and downstairs. At ElWell we provide a physiotherapy service at home in Oxfordshire or you can find one through the CSP (Chartered Society of Physiotherapy) Find a Physio. Alternatively visit your GP and request a referral. Using the wrong walking stick or using it with a poor technique can be unsafe and lead to an increased risk of falls. Different Types Of Walking Sticks Foldable Walking Stick For something a bit more fun and discreet choose a patterned foldable walking stick which you can use just when needed. Adjustable Walking Stick Lightweight strong and adjustable, here is a standard adjustable walking stick. Walking Sticks With Seats If you tire easily and have reasonably good balance, then a walking stick with a seat can be a good option. If you need to rest for longer periods or need help carrying shopping look at our walking aid guide and consider an outdoor walker. Types of Wheelchairs A wheelchair is comprised of a seat with four wheels attached. The wheels towards the back are usually bigger and have rims that you can use to push the chair forward or backward and to turn. There are many types of wheelchairs. Electrical wheelchair is one that you can propel with a motor. You use a joystick or other control device to help steer, start, and stop the chair. These types of wheelchairs are usually very heavy and bulky due to the battery pack that powers the wheelchair. A manual wheelchair is one that you push using your arms. Another person can also help push the wheelchair with handles on the back of the chair. Many manual wheelchairs are able to be folded to make them easy to transport and store. There are many moving parts on the wheelchair, so folding and unfolding the wheelchair can be challenging. By following these basic instructions, folding and unfolding a wheelchair will be a breeze. Keep in mind that not all wheelchairs are alike and that the instructions below should be useful for most manual folding wheelchairs. Your wheelchair may be different, so if you are having a hard time folding or unfolding it, please consult your doctor or local physical therapist for help. Opening and Closing a Wheelchair To open or unfold the wheelchair: Place your wheelchair on a solid even surface. Make sure the brakes are locked. You do not want your wheelchair rolling away from you as you try to open it up. Usually, there are small levers in front of each rear wheel that engage to lock the wheels. Grab the seat of the wheelchair with one hand in the front and one in the back. Slowly push the seat down in the middle of the seat. The sides and wheels of the wheelchair should slide away from one another. Push all the way down until the seat is fully opened. Your wheelchair is now ready for use. Be sure the brakes are locked before attempting to sit in your wheelchair. To close or fold the wheelchair: Make sure the brakes are applied to the wheelchair. Stand in front of the wheelchair and grab the seat of the chair with one hand in the front and one hand in the back. Slowly lift up on the seat. The seat should fold in half and the wheels should move closer together. Fully raise the seat in the middle, and the wheelchair should be folded up and ready to transport or store.
Data publikacji: 06-08-21
Opis: Introduction to Partition Walls: Partition Walls also called Stud Walls are unloaded walls intended to separate apart within a building, to form an interior room/cabinet, or to separate the laundry area from the rest of the building. Since partitioning walls can be loaded with a roof, therefore, they are built solely for the purpose of partitioning. They are not as strong as all the other loaded walls. The partition wall has 12 types. Each type is distinguished from the other on the basis of the materials used in it. Therefore, the definition of each type is a description of the materials used in partition walls. Different Types of Partitioning Walls: 1. Partitioning of brick walls: The purpose of a brick wall is similar to that of other types of walls, such as separating one part of a building from another, separating a room, making one interior cabinet, separating one part of that part from another. A brick dividing wall was built with the task of building bricks. A brick wall takes a lot of time to build. Not suitable for the earthquake zone. The advantage of a brick partition wall is that it is not expensive. 2. Partitioning walls made of certified bricks: Reinforced bricks are made of reinforced material to add strength to bricks. This type of wall is very strong and durable. The disadvantage of this type of movable partition wall is that these walls are heavy and use a lot of load on the floor. 3. Differing a Wall made with Hollow & Clay Brick: Empty concrete is made of units of concrete and clay bricks are made only of clay. Since these types of bricks are empty on the inner side, so they are lightweight and do not put a lot of load on the floor. This is cheaper to build, but not as strong as reinforced partition walls. 4. Partition wall by concrete material: Concrete separating concrete is made of concrete made of stone, sand, and cement. Sometimes iron/steel rods are inserted into the concrete material to strengthen it further. Like a brick wall, and a reinforced brick wall, this too is very strong, but still places a heavy load on the lower floor. 5. Glass made Partitions Wall: The glass partition is made of glass. Thick glass panels, hollow glass blocks, or PVC panels are used to create this type of wall. Most glass used for activity partition walls may be made of opaque glass or other adhesive adhesives are attached to the glass wall to protect privacy. 6. Grass Boards as Building Blocks of Partitions Walls: These types of walls are easily moved from one place to another. Grass boards are less expensive and weigh less. These are not built permanently but are placed in one place and in time these walls are moved to another location. 7. Partition walls made of Paris cement and burnt minerals: This type of wall is made of Paris plaster plates or burnt minerals. This is very easy to build, but it does not last very long. These types of walls are well built and their finish is very smooth. These types of walls are easily built and easily demolished. 8. Different Walls Made with Metal Lath: Steel frames or planks are used to fix metal parts. These steel straps are tight, strong, and durable. Lath is fastened with steel wire attached to soft metal bars or channels separated by 15 to 30 cm. These metal bars are attached to the farm on both sides to protect from heat and compaction. 9. Walls built with A.C. & G.I Spreadsheets: These sheets are cut with wood or metal strips to create a texture on both sides. These sheets are economical, lightweight, and durable. Each slab has a basic or metal asbestos cement sheet (5mm) with a plain asbestos cement sheet (10mm) attached to that in any part. 10. Partition Walls made up of Wood: Wood partition walls are also strong, durable, and economical. Wood partition walls can be repaired or moved. If the wall cannot be moved, it should have a di-pode stand. 11. Wooden Partition Walls: Wood is the name of the wood used in the USA. The wooden partition is a wooden frame supported by a floor or sidewalls. The structure consists of a solid arrangement of wooden parts, which can be plastered or boarded up, etc. on each side. Not them. 12. Abestos Partition Walls: Asbestos is a silicate mineral, used for construction purposes. Like the Paris plaster, it is easy to build and can be easily constructed. Another advantage of Asbestos Cement is water resistance. Asbestos cement sheets are laid with wooden or metal frames. 13. Double glazed windows as Partition Walls: It is used as acoustic insulation with soundproofing material. Two acoustic panels are placed at a distance of 50 mm. The space is full of air. The air contained in the middle of the small spine is a kind of 'firmness' and transmits vibrations in low waves, especially though acoustic foam. Specific members give the program a glossy "flawless" look. Glossy partition walls are widely used in all offices, private meeting places, and board rooms. The partition walls mentioned above are of different types. This section is based on the material used for each type of partition wall. The durability and cost also vary with each type of wall. Walls made of concrete and reinforced concrete or steel materials are stronger than the walls built by Asbestos and the Plaster of Paris. The attractiveness and beauty of the wall also depend on the type of material used. There are some dividing walls that are not built with individual materials. They are made of composite materials. Using composite materials can add strength, beauty, and durability to walls.
Data publikacji: 06-08-21
Opis: An account of an acoustic newbie's journey from bare walls to a well?balanced, sonically pleasant space. The physics of the propagation of sound is immensely complicated, and when the assortment of materials that make up the walls, floors and ceiling (plus any windows, doors and furniture) are added to the equation, it's very difficult to predict what will happen to sound waves once they've left their source. What's more, every room is different, and it's not just the dimensions that will dictate how the room will sound... Imagine two rooms of the same shape and size. One has two?metre-thick concrete walls, and the other a single?layer plasterboard stud-wall. Even with those brief, albeit extreme descriptions, you probably know already that the two rooms will sound very different. Add in the multitude of room shapes, sizes, wall?construction methods and surfaces found in home studios, and it becomes impossible to provide a one-size-fits-all guide to acoustic panel treatment. The subject of acoustics is regularly discussed in SOS, but plenty of readers still ask for the subject to be covered from a much more basic starting point. What follows is a look at installing acoustic treatment from a complete beginner's perspective: some basic, essential information, along with a bit of advice from acoustics professionals that should give you the confidence to get started. I'll follow this up by taking you step by step through my own recent experience of treating a room. Why Bother With Acoustic Treatment? Untreated rooms have an uneven frequency response, which means that any mixing decisions you make are being based on a sound that is 'coloured', because you can't accurately hear what's being played. In short, you can't possibly tell how your mix will sound when played back anywhere else. It isn't just an issue for mixing, though, because any recordings you make of acoustic instruments will bear all the hallmarks of the space in which you record them. That may be a good thing if the space in question is Ocean Way or SARM West, but probably preposterously bad if it's your living room or bedroom. So, if you want your mixes to transfer well, and your recordings to be free of room 'honk', you need to pay attention to the acoustic properties of your environment — no matter how good the gear you're using. First Things First The first thing to grasp is the outcome you want to achieve. It's a common misconception that acoustic treatment with acoustic ceilings or acoustic baffles should kill all reverberation, and that you want a room covered floor?to?ceiling with foam tiles: this isn't what you're aiming for. You also need to bear in mind the limitations imposed by space and budget: most home studios are small in comparison with the Abbey Roads and AIR Lyndhursts of this world, and many home?studio owners simply don't have the funds for bespoke treatment solutions. So what is the aim? Andy Munro, acoustic design specialist, remarks, "acoustic design is the science that restores a neutral sound balance”. Applying that science means interfering with the path of sound to control the sound energy. Jorge Castro, chief acoustician at Vicoustic, says that "in the case of affordable treatment, we need to control the energy of the sound first. Then we can take care of the sound quality. With small spaces, bass frequencies are always a problem, and we should control the low frequencies as much as we can.” In fact, he continues, "In small rooms, I've never heard people saying they have too much absorption of low frequencies.” Absorption & Diffusion: What, Where, Why? To achieve the right balance, there are two main approaches: absorption and diffusion. Products that have absorptive properties include foam and rigid mineral-wool (see the 'DIY & Rockwool' box), and they 'soak up' the sound energy, turning it into heat, through friction. Most effective on high?frequencies, absorption is essential for reducing flutter echoes and for taming bright?sounding or 'ringy' rooms. Bass trapping is also a type of absorption, but is specifically designed to absorb low?frequency energy. A clever combination of soft, hard, thick and thin materials, including air, is used to make the most efficient bass trap, and an empty gap between the wall and the back of the trap helps to make it even more effective. Diffusion is the scattering of sound energy using multi?faceted surfaces. Diffusers are commonly made of wood, plastic, or even polystyrene. Jorge Castro explains: "diffusion helps in energy control and improves the sound quality in frequencies throughout the middle and high range of the spectrum, and also improves sweet?spot image.” The 'sweet spot' is the place between the speakers where you should be sitting to get the best stereo image (imagine that your head and the two speakers form an equilateral triangle). That pretty much concludes the theory: now for the practice! Getting Started Before undertaking this project, I'd read plenty about acoustics, but had never attempted to properly treat a room myself: the nearest I'd come was propping foam panels against the walls to tame flutter in the spare?room?cum?studio of my rented house. I hadn't been able to glue or screw anything to the walls, for fear of incurring my landlord's wrath, and the thought of retouching the paintwork after tearing strips of self?adhesive velcro pained me too! So this was very much a learning experience. The space in question included an area that would provide a reasonable?sized live room, and another that would serve as a small control room, and although both were important, I really wanted to get the performance space right. I decided that I'd buy commercially available panels, because I simply didn't have the time, space or inclination for the DIY option. Most manufacturers of acoustic products also offer a consultation service, and they often have free on?line calculators to help you decide on a suitable treatment option, too, so even if you choose the DIY route this can be a sensible place to start, and fabric acoustic panels are also available. I chose to get my treatment from Vicoustic, a company relatively new to the UK acoustic?treatment market who make a range of products for studios and home theatres. I told them that, as this was the only live room for a small project studio, it needed to be quite versatile, with both a 'dead' corner for dry recordings and a more ambient space to liven up acoustic recordings where needed. I'd expected a solution with almost complete wall coverage, foam panels and diffusers covering every square inch, but Vicoustic came back with a plan that surprised me, which suggested that total coverage wasn't necessary. In fact, Jorge says that the typical home studio needs only between 30 and 40 percent coverage to adequately treat it. So don't go over the top: remember that we're trying to control the energy, or "restore the natural sound balance,” and not to kill the sound completely. As for the proportion of diffusion to absorption, Jorge says, "some believe it should be 50 percent absorption and 50 percent diffusion. In the home studio, because of budget and space constraints, the actual proportion can vary considerably.” Planning So, you've decided on your acoustic foam treatment, you've had it delivered, and it's piled in the middle of the room. The next step is sticking it up on the walls, right? Well yes... but you also want to make sure that it goes in the right place, partly to optimise its acoustic performance, and partly because you don't want it to look like it's been put up by a two?year old! As a first?timer, I found it useful to have the 3D drawings Vicoustic had supplied, as they enabled me to plan precisely where each panel would go. You can create a computer?generated version of your room yourself using a freeware 3D drawing programme such as Google Sketchup (http://sketchup.google.com). This may seem a bit over the top (sketches on the back of an envelope would do the job), but it can provide a useful guide to print out and use like a map during installation. What's more, you can plan the look of a room, moving tiles and panels around on the computer instead of having to rip them off the wall if they look silly. Measure Twice, Stick Once With my 'map' in hand, it was time to mark up the walls. The Vicoustic plans showed the panels equally spaced along the walls, but without any dimensions or measurements to indicate how to space the tiles, so I measured the whole room and planned the position of all the panels supplied. A quick and easy formula for plotting the position of a row of equally spaced panels soon emerged. To calculate the distance between each panel, and between the end panels and the walls, you just measure the length of the wall, subtract the total width of all the panels to be fixed to it, then divide that figure by the number of gaps between panels (or by the number of panels plus one). Marking up is then a cinch, but to get things looking good, you'll need to mark the corner points and will require a spirit level and a spare pair of hands. Once plotted and marked, it's also a good idea to double?check that you have the same number of actual panels as you have on your plan! Stick 'Em Up! With the planning done, it's time to stick the panels to the walls and ceiling. The way you do this depends on the type of treatment you're applying. Large, framed panels will come with brackets and (hopefully) sturdy fixings, whereas foam?based tiles will need to be glued, using an aerosol?based product or a tube of paste?like glue that needs a skeleton gun. Spray?mounting can often give less than satisfactory results, so I was glad to discover that the Vicoustic delivery included the tube variety. With just two tubes supplied, though, I soon had to resort to alternatives, and found that the sticky gunk used to fix mirrors to walls worked exceptionally well. To prevent the glue squidging out from the sides of the panels, I piped the glue on no less than an inch from the guide line on the wall and on the back of the panel itself, in different patterns, to increase the adhesion. With this kind of glue, I found that it would begin to set in about a minute, allowing just enough time to pull the panel off and turn it if it was the wrong way up. When sticking panels to the ceiling, I took the same approach. It was a textured ceiling, which called for lots of glue and a firm hand to seat the panels: again, it's useful if you can get a friend to lend a hand. Hearing The Result Once in place, the Vicoustic treatment worked very well. The main part of the room is now nicely controlled, if a bit on the 'live' side, and the diffusers ensure excellent intelligibility of speech: a sure?fire sign of good acoustic control. I had a few spare corner traps, which were put into the dry corner, to make it even more 'dead', and it will be easy to add a few smaller foam tiles to dampen the sound further if it's found to be too 'roomy' further down the line. Having tried some recordings in the room, I'm happy to say that excellent sound barrier can be achieved between acoustic instruments and vocals by using the different areas of the room. Because the sound inside the room is controlled, the ambience can be used to good effect if a roomy sound is desired on the recording. Ultimate Control So far, I've only addressed the dedicated live/recording space, and most home studios are single rooms, with both the monitoring and performance areas in the same space, so I asked Andy Munro to explain how to approach treating such a space. "The best approach,” he said, "is to sketch the room out, then divide each dimension into thirds. If the mixing position is on a third ratio, and so are the speakers, they will not stand on any of the half or quarter 'standing' wavelengths that cause a peak or trough in the bass . The result will be a smoother sound, with fewer problems when the acoustic absorption and sound barrier is added. Ironically, most professional rooms are set up about the centre line, which tends to result in a 'hole' at certain frequencies.” Also important in monitoring rooms is the control of early reflections. When a speaker cone is driven, it disperses acoustic energy to the listener's ears directly, and also to the walls and ceiling of the room, and the best example may be acoustic diffuser. Uncontrolled, these early reflections bounce back into the room and reach the listener a few milliseconds later than the direct sounds, because of the additional distance they've had to travel. Unless in a large room, this delay is not perceivable as a different sound; instead it disturbs the phase, and therefore the clarity, of the sound. To keep early reflections on a tight leash, the 'mirror points' of the room should be identified and treated. To do this, sit in the listening position and 'guesstimate' where a mirror would have to be placed to enable you to see each monitor cone from the sweet spot. Then apply absorption to these points. A 'ceiling cloud' can be positioned in a similar way, to control vertical reflections. Conclusion No matter how much you spend on instruments, amps, speakers and recording gear, you still need to pay attention to the space in which you use them. The treatment of home studios is tricky, because of their size and the construction materials used, not to mention the budget of the average home?studio owner. It's impossible to get a 'pro-studio sound' from a space that's built as a spare bedroom, mainly due to the laws of physics, but also because 'proper' studios might have big bucks spent on acoustic design with soundproof materials. But if you can get your head around what you're trying to achieve, you can still make such a space perfectly usable, with only a small amount of money, some forward planning and a little bit of knowledge.
Data publikacji: 06-08-21