What is a sonar pulse and how can it injure humans under water?

An echo sounder on a boat uses sound waves to help gauge the depth of the water. mark_vyz/Shutterstock Christine Erbe, Curtin University

Over the weekend, the Australian government revealed that last Tuesday its navy divers had sustained “minor injuries”, likely due to sonar pulses from a Chinese navy vessel.

The divers had been clearing fishing nets from the propellers of HMAS Toowoomba while in international waters off the coast of Japan. According to a statement from deputy prime minister Richard Marles, despite HMAS Toowoomba communicating with internationally recognised signals, the Chinese vessel approached the Australian ship and turned on its sonar, forcing the Australian divers to exit the water.

The incident prompted a response from the Australian government, who labelled the incident “unsafe and unprofessional”. But what exactly is a sonar pulse, and what kinds of injuries can sonar cause to divers?

What is sonar?

Light doesn’t travel well under water – even in clear waters, you can see perhaps some tens of metres. Sound, however, travels very well and far under water. This is because water is much denser than air, and so can respond faster and better to acoustic pressure waves – sound waves.

Because of these properties, ships use sonar to navigate through the ocean and to “see” under water. The word “sonar” stands for sound navigation and ranging.

Sonar equipment sends out short acoustic (sound) pulses or pings, and then analyses the echoes. Depending on the timing, amplitude, phase and direction of the echoes the equipment receives, you can tell what’s under water – the seafloor, canyon walls, coral, fishes, and of course ships and submarines.

Most vessels – from small, private boats to large commercial tankers – use sonar. However, compared to your off-the-shelf sonar used for finding fish, navy sonars are stronger.

What are the effects of sonar on divers?

This is a difficult topic to study, because you don’t want to deliberately expose humans to harmful levels of sound. There are, however, anecdotes from various navies and accidental exposures. There have also been studies on what humans can hear under water, with or without neoprene suits, hoods, or helmets.

We don’t hear well under water – no surprise, since we’ve evolved to live on land. Having said that, you would hear a sonar sound under water (a mid-to-high pitch noise) and would know you’ve been exposed.

When it comes to naval sonars, human divers have rated the sound as “unpleasant to severe” at levels of roughly 150dB re 1 µPa (decibel relative to a reference pressure of one micropascal, the standard reference for underwater sound). This would be perhaps, very roughly, 10km away from a military sonar. Note that we can’t compare sound exposure under water to what we’d receive through the air, because there are too many physical differences between the two.

Human tolerance limits are roughly 180dB re 1 µPa, which would be around 500m from military sonar. At such levels, humans might experience dizziness, disorientation, temporary memory and concentration impacts, or temporary hearing loss. We don’t have information on what levels the Australian divers were exposed to, but their injuries were described as minor.

At higher received levels, closer ranges, or longer exposures, you might see more severe physiological or health impacts. In extreme cases, in particular for impulsive, sudden sound (which sonar is not), sound can cause damage to tissues and organs.

What does sonar do to marine animals?

Some of the information on what noise might do to humans under water comes from studies and observations of animals.

While they typically don’t have outer ears (except for sea lions), marine mammals have inner ears that function similarly to ours. They can receive hearing damage from noise, just like we do. This might be temporary, like the ringing ears or reduced sensitivity you might experience after a loud concert, or it can be permanent.

Marine mammals living in a dark ocean rely on sound and hearing to a greater extent than your average human. They use sound to navigate, hunt, communicate with each other and to find mates. Toothed whales and dolphins have evolved a biological echo sounder or biosonar, which sends out series of clicks and listens for echoes. So, interfering with their sounds or impacting their hearing can disrupt critical behaviours.

Finally, sound may also impact non-mammalian fauna, such as fishes, which rely on acoustics rather than vision for many of their life functions.

Christine Erbe, Director, Centre for Marine Science & Technology, Curtin University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Read More........→November 22, 2023

Fieldwork can be challenging for female scientists. Here are 5 ways to make it better

Merla, Shutterstock

Sarah Hamylton, University of Wollongong; Ana Vila Concejo, University of Sydney; Hannah Power, University of Newcastle, and Shari L Gallop, University of Waikato

Women coastal scientists face multiple barriers to getting into the field for research. These include negative perceptions of their physical capabilities, not being included in trips, caring responsibilities at home and a lack of field facilities for women. Even if women clear these barriers, the experience can be challenging.

This is a problem because fieldwork is crucial for gathering data, inspiring emerging scientists, developing skills, expanding networks and participating in collaborative research.

Our recent study revisited an international survey of 314 coastal scientists that revealed broad perceptions and experiences of gender inequality in coastal sciences. We offer five ways to improve the fieldwork experience for women.

Our collective experience of more than 70 years as active coastal scientists suggests women face ongoing problems when they go to the field. Against a global backdrop of the #MeToo movement, the Picture a Scientist documentary and media coverage about incidents of sexual harassment in the field, conversations between fieldworkers and research managers about behaviour and policy change are needed.

Disrupting the narrative: Women fieldworkers operating equipment, carrying gear and fixing engines. Women in Coastal Geosciences and Engineering network

Our research: what we did and what we found

In 2016, we surveyed both male and female scientists about their experiences of gender equality in coastal sciences during an international symposium in Sydney and afterwards online.

From 314 responses, 113 respondents (36%) provided examples of gender inequality they had either directly experienced or observed while working in coastal sciences. About half of these were related to fieldwork.

Our recent paper in the journal Coastal Futures revisits the survey results to further unpack fieldwork issues that continue to surface among the younger generation of female coastal scientists whom we supervise in our jobs. Many of those younger women don’t know how to address these issues.

The paper includes direct quotes from 18 survey respondents describing their experiences. One woman, a mid-career university researcher, said:

As I fill in this survey, the corridor of the building I work in is lined with empty offices. My colleagues are out on boats doing fieldwork. I have a passion for coastal science. That’s why I’m working in a university. But I have a disproportionately large share of administrative, pastoral and governance duties that keep me from engaging in my passion. I’m about to go to a committee meeting of women, doing women’s work (reviewing teaching offerings). Inequality is alive and well in my workplace!

Collectively, the responses highlight barriers to fieldwork participation and challenges in the field, such as sexual harassment and abuse.

A pressing issue, on and off campus

Universities have recently been criticised for failing to respond to sexual violence on campus. But women employed by universities working off campus – at field sites – can be even more vulnerable.

The social boundaries that characterise day-to-day working life in the office and the laboratory are reconfigured on boats or in field camps. Personal space is reduced. Fieldworkers can be required to sleep in close proximity to one another, potentially putting women in vulnerable situations.

As this female early-career university researcher wrote:

Sometimes women are ‘advised’ to avoid fieldwork for security reasons. Or [we] are considered weak, or we are threatened by rape for being with a lot of men.

Women working on boats commonly face inadequate facilities at sea for toileting, menstruation and managing lactation. Some women said they were “not allowed to join research vessels” or “prevented from [joining] research in the field because of gender”.

Reminded of our personal experiences

Just reading the survey responses was difficult for us. Tales of exclusion and discrimination were particularly confronting because they resonated with our own personal experiences. As one of us, Sarah Hamylton, recalls:

I remember spending a hot day in my early 20s on a small boat taking measurements over a reef. I was the only female. When one of the four guys asked about needing the toilet, he was told to stand and relieve himself off the stern. I had to hold on, so I was desperate when we returned to the main ship in the afternoon.

But that wasn’t the only challenge Hamylton encountered on that trip:

We got back into port and the night before we departed to go home, I was woken by the drunken second officer banging on my cabin door asking for sex. The following year women were banned from attending this annual expedition because someone else had complained about sexual assault.

Gender stereotypes and discrimination

Coastal fieldwork demands diverse physical skills such as boating, four-wheel driving, towing trailers, working with hand and power tools, moving heavy equipment, SCUBA diving and being comfortable swimming in the surf, in currents or underwater.

But our survey revealed roles on field trips – and therefore opportunities to learn and gain crucial field skills – are typically handed to men rather than women. Several respondents observed female students and staff being left out of field work for “not being strong enough” and “too weak to pick stuff up”.

Body exposure can also be an issue for women in the field. Close-fitting wetsuits and swimsuits can increase the likelihood of womens’ bodies being objectified by colleagues. Undertaking coastal fieldwork while menstruating can also be a concern.

Another of us, Ana Vila-Concejo, notes:

Some scientific presentations show women in bikinis as a ‘beach modelling’ joke. Beyond self-consciousness, I have felt vulnerable wearing swimmers and exerting myself during fieldwork. Women students and volunteers have declined to participate in field experiments for this reason, particularly while menstruating.

The issue of body exposure also sheds light on the interconnections between race, religion, class and sexuality, which can create overlapping and intersectional disadvantages for women. Vila-Concejo adds:

I am old enough now that I don’t care anymore. I can afford a wetsuit, but many students and volunteers don’t have one. For some women, it isn’t socially or culturally acceptable to wear swimmers, or even to do fieldwork.

Five suggestions for improvement

To improve the fieldwork experience for women in coastal sciences, our research found the following behavioural and policy changes are needed:

1. publicise field role models and trailblazers to reshape public views of coastal scientists, increasing the visibility of female fieldworkers

2. improve opportunities and capacity for women to undertake fieldwork to diversify field teams by identifying and addressing the intersecting disadvantages experienced by women

3. establish field codes of conduct that outline acceptable standards of behaviour on field trips, what constitutes misconduct, sexual harassment and assault, how to make an anonymous complaint and disciplinary measures

4. acknowledge the challenges women face in the field and provide support where possible in fieldwork briefings and address practical challenges for women in remote locations, including toileting and menstruation

5. foster an enjoyable and supportive fieldwork culture that emphasises mutual respect, safety, inclusivity, and collegiality on every trip.

These five simple steps will improve the experience of fieldwork for all concerned and ultimately benefit the advancement of science.

Sarah Hamylton, Associate professor, University of Wollongong; Ana Vila Concejo, Associate professor, University of Sydney; Hannah Power, Associate Professor in Coastal and Marine Science, University of Newcastle, and Shari L Gallop, Service Leader - Coastal, University of Waikato

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Read More........→November 06, 2023

Is it okay to kiss your pet? The risk of animal-borne diseases is small, but real

Shutterstock Sarah McLean, Swinburne University of Technology and Enzo Palombo, Swinburne University of Technology

Our relationship with pets has changed drastically in recent decades. Pet ownership is at an all-time high, with a recent survey finding 69% of Australian households have at least one pet. We spend an estimated A$33 billion every year on caring for our fur babies.

While owning a pet is linked to numerous mental and physical health benefits, our pets can also harbour infectious diseases that can sometimes be passed on to us. For most people, the risk is low.

But some, such as pregnant people and those with weakened immune systems, are at greater risk of getting sick from animals. So, it’s important to know the risks and take necessary precautions to prevent infections.

 
What diseases can pets carry?

Infectious diseases that move from animals to humans are called zoonotic diseases or zoonoses. More than 70 pathogens of companion animals are known to be transmissible to people.

Sometimes, a pet that has a zoonotic pathogen may look sick. But often there may be no visible symptoms, making it easier for you to catch it, because you don’t suspect your pet of harbouring germs.

Zoonoses can be transmitted directly from pets to humans, such as through contact with saliva, bodily fluids and faeces, or indirectly, such as through contact with contaminated bedding, soil, food or water.

Studies suggest the prevalence of pet-associated zoonoses is low. However, the true number of infections is likely underestimated since many zoonoses are not “notifiable”, or may have multiple exposure pathways or generic symptoms.

Dogs and cats are major reservoirs of zoonotic infections (meaning the pathogens naturally live in their population) caused by viruses, bacteria, fungi and parasites. In endemic regions in Africa and Asia, dogs are the main source of rabies which is transmitted through saliva.

Dogs also commonly carry Capnocytophaga bacteria in their mouths and saliva, which can be transmitted to people through close contact or bites. The vast majority of people won’t get sick, but these bacteria can occasionally cause infections in people with weakened immune systems, resulting in severe illness and sometimes death. Just last week, such a death was reported in Western Australia.

Cat-associated zoonoses include a number of illnesses spread by the faecal-oral route, such as giardiasis, campylobacteriosis, salmonellosis and toxoplasmosis. This means it’s especially important to wash your hands or use gloves whenever handling your cat’s litter tray.

Cats can also sometimes transmit infections through bites and scratches, including the aptly named cat scratch disease, which is caused by the bacterium Bartonella henselae.

Both dogs and cats are also reservoirs for methicillin-resistant bacterium Staphylococcus aureus (MRSA), with close contact with pets identified as an important risk factor for zoonotic transmission.

Dog saliva hosts a bacterium that can cause serious illness and even death in some people. Shutterstock 

Birds, turtles and fish can also transmit disease:

But it’s not just dogs and cats that can spread diseases to humans. Pet birds can occasionally transmit psittacosis, a bacterial infection which causes pneumonia. Contact with pet turtles has been linked to Salmonella infections in humans, particularly in young children. Even pet fish have been linked to a range of bacterial infections in humans, including vibriosis, mycobacteriosis and salmonellosis.

Close contact with animals – and some behaviours in particular – increase the risk of zoonotic transmission. A study from the Netherlands found half of owners allowed pets to lick their faces, and 18% allowed dogs to share their bed. (Sharing a bed increases the duration of exposure to pathogens carried by pets.) The same study found 45% of cat owners allowed their cat to jump onto the kitchen sink.

Kissing pets has also been linked to occasional zoonotic infections in pet owners. In one case, a woman in Japan developed meningitis due to Pasteurella multicoda infection, after regularly kissing her dog’s face. These bacteria are often found in the oral cavities of dogs and cats.

Young children are also more likely to engage in behaviours which increase their risk of getting sick from animal-borne diseases – such as putting their hands in their mouth after touching pets. Children are also less likely to wash their hands properly after handling pets.

Although anybody who comes into contact with a zoonotic pathogen via their pet can become sick, certain people are more likely to suffer from serious illness. These people include the young, old, pregnant and immunosuppressed.

For example, while most people infected with the toxoplasmosis parasite will experience only mild illness, it can be life-threatening or cause birth defects in foetuses. Young children under 5 years old are more at risk of zoonotic diseases, and also more likely to engage in behaviours that increase their chances of catching something from their pet. Shutterstock

What should I do if I’m worried about catching a disease from my pet?

There are a number of good hygiene and pet husbandry practices that can reduce your risk of becoming sick. These include:

• washing your hands after playing with your pet and after handling their bedding, toys, or cleaning up faeces
• not allowing your pets to lick your face or open wounds
• supervising young children when they are playing with pets and when washing their hands after playing with pets
• wearing gloves when changing litter trays or cleaning aquariums
• wetting bird cage surfaces when cleaning to minimise aerosols
• keeping pets out of the kitchen (especially cats who can jump onto food preparation surfaces)
• keeping up to date with preventative veterinary care, including vaccinations and worm and tick treatments
• seeking veterinary care if you think your pet is unwell.

It is especially important for those who are at a higher risk of illness to take precautions to reduce their exposure to zoonotic pathogens. And if you’re thinking about getting a pet, ask your vet which type of animal would best suit your personal circumstances.

Sarah McLean, Lecturer in environmental health, Swinburne University of Technology and Enzo Palombo, Professor of Microbiology, Swinburne University of Technology

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Read More........→September 06, 2023

Why Should You Breastfeed Your Baby?

(Photo courtesy of Flushing Hospital Medical Center)

Flushing Hospital Medical Center’s New Beginnings unit provides the women and their families with the ultimate birthing experience. Each month, we cover a new topic exploring an important aspect of health and well-being for expectant mothers. This month, we’ll cover the health benefits of exclusive breastfeeding for both mothers and their babies. According to the American Academy of Pediatrics, exclusive breastfeeding involves only feeding breast milk to your baby and no other foods or liquids. It is the best source of nutrition for your infant’s first six months of life. 

Some of the benefits to babies and mothers include: 

• Providing all necessary nutrients for the baby’s healthy physical development, including vitamin D, iron, and zinc
• Preventing infections and serious health conditions, both during infancy and later in life
• Reducing a mother’s risk of conditions such as cancer, type 2 diabetes, and high blood pressure

Breastfeeding may become less frequent as your baby starts eating solid foods around six to 12 months of age. For guidance on how you should breastfeed your baby, talk to a lactation consultant or your baby’s doctor or nurse.Flushing Hospital’s New Beginnings unit offers spacious, modern delivery suites and advanced postpartum care, providing you with a safe environment to give birth and comprehensive follow-up medical support for you and your baby. To learn more about the unit, including accommodations and services provided, please call us at Source: https://www.newsindiatimes.com/

Read More........→August 23, 2023

Why Men Find Switching Tasks More Difficult Than Do Women

It has long been known to science that women find it easier than men to multitask and switch between tasks. But identifying exactly which areas of male and female brains respond differently and why has so far been unclear. According to researchers from the HSE Neurolinguistics Laboratory, men need to mobilise additional areas of their brain and use more energy than women when multitasking.

Why Men Find Switching Tasks More Difficult

Needing to switch attention between tasks causes stronger activation in certain brain regions in men compared to women.

Although women find it easier than men to switch between tasks; how exactly their brains function differently in such situations has so far been unknown. Recent research reveals that male brains appear to consume more energy when they need to shift attention. In addition to this, in men there is greater activity in the dorsolateral prefrontal areas of the brain compared to women, as well as activation in some other areas which is not usually observed in women.

Such differences are typical of younger men and women aged 20 to 45, according to findings from experiments conducted by researchers Svetlana Kuptsova and Maria Ivanova of the HSE Neurolinguistic Laboratory, radiologists Alexey Petrushevsky and Oksana Fedina of the Centre for Speech Pathology and Neurorehabilitation, and Ludmila Zhavoronkova, Doctor of Biology and Senior Research Fellow of the RAS Institute of Higher Nervous Activity and Neurophysiology. The study's findings have been published in Human Physiology, an international peer-reviewed journal.

Higher Activity, Slower Speed

Regardless of gender and age, task switching always involves activation in certain areas of the brain, more specifically, bilateral activation of the dorsolateral prefrontal areas, inferior parietal lobes and inferior occipital gyrus.

However, experiments conducted by Kuptsova et al. demonstrate that in women, task switching appears to require less brain power compared to men, who showed greater activation in the dorsolateral prefrontal areas as well as the involvement of supplementary motor areas and insula, which was not observed in women.

"We know that stronger activation and involvement of supplementary areas of the brain are normally observed in subjects faced with complex tasks. Our findings suggest that women might find it easier than men to switch attention and their brains do not need to mobilise extra resources in doing so, as opposed to male brains," explained Kuptsova.

The experiments involved 140 healthy volunteers, including 69 men and 71 women aged between 20 and 65. The subjects were asked to perform a variety of tasks. In one of the experiments using functional MRI, they were asked to perform a test that required switching attention between sorting objects according to shape (round or square) and number (one or two), in a pseudo-random order. In addition to this, neuropsychological tests were conducted, including the D-KEFS Trail Making Test to measure the subjects' ability to switch attention and the Wechsler Memory Scale test to measure their audial and visual memory.

The use of functional MRI allowed the researchers not only to observe the subjects' behaviour, but also to see what was going on in the brain as subjects switched between tasks and detect differences in brain activation between men and women.

Age versus Gender

The researchers found that the gender differences in the extent of brain activation when switching between tasks only occurred in subjects younger that 45-50, while those aged 50 and older showed no gender differences either in brain activation or speed of task switching.

According to the researchers, older men and women - starting at the age of 45 in women and 55 in men - experienced both increased activation of key areas involved and mobilisation of additional brain resources.

Brain Mystery

The study has once again confirmed that young women tend to cope with attention switching better than young men. While the reaction time is demonstrably different, according to Kuptsova, it is barely noticeable in everyday life, except perhaps that, "it might make a difference in really stressful circumstances or in critical situations which require frequent switching of attention."

However, science cannot currently explain the exact reasons for this difference. Any assumptions as to why nature might need it are nothing but speculation, Kuptsova argues.

For example, there is a popular hypothesis by American psychologist Jerre Levy as to why men tend to have better spatial skills while women are often better at more verbal tasks. According to Levy, these differences are caused by both evolutionary and social factors. In ancient times, men spent their time hunting, which required good spatial abilities, while women were caring for children and thus needed good communication skills. In the course of evolution, these survival skills have been passed down to future generations.

"We could continue with the same logic and assume that homemaking and caring for children historically required women to be good at multitasking, but there is no hard evidence to support this theory," Kuptsova concludes.

The study was hosted by the Centre for Speech Pathology and Neurorehabilitation.

Contacts and sources:

National Research University - Higher School of Economics (HSE)

Citation: Sex- and age-related characteristics of brain functioning during task switching (fMRI study) Authors Authors and affiliations S. V. KuptsovaEmail authorM. V. Ivanova, A. G. Petrushevskiy, O. N. FedinaL. A. Zhavoronkova. Human Physiology July 2016, Volume 42, Issue 4, pp 361–370 2016 DOI: 10.1134/S0362119716040101 Source: http://www.ineffableisland.com/

Read More........→November 22, 2016