In material physics understanding how systems interact across the interfaces separating them is of central interest. But can physical models clarify similar concepts in living systems, such as cells? Physicists at the University of Geneva (UNIGE), in collaboration with the University of Zurich (UZH), used the framework of disordered elastic systems to study the process of wound healing — the proliferation of cell fronts which eventually join to close a lesion. Their study identified the scales of the dominant interactions between cells which determine this process. The results, published in the journal Scientific Reports, will allow better analysis of cell front behaviour, in terms of both wound healing and tumour development. In the future, this approach may offer personalised diagnostics to classify cancers and better target their treatment, and identify new pharmacological targets for transplantation.
By focusing on macroscopic properties of large datasets, statistical physics makes it possible to extract an overview of system behaviour independent of its specific microscopic character. Applied to biological elements, such as the cell fronts bordering a wound, this approach makes it possible to identify the various interactions which play a defining role during tissue growth, differentiation, and healing, but above all to highlight their hierarchy at the different scales observed. Patrycja Paruch, professor in the Department of Quantum Matter Physics at the UNIGE Faculty of Science, explains: “For cancer tumour invasion, or in the event of a wound, cell front proliferation is crucial, but the speed and morphology of the front is highly variable. However, we believe that only a few dominant interactions during this process will define the dynamics and the shape — smooth or rough, for example — of the cell colony edge. Experimental observations across multiple lengthscales to extract general behaviours can allow us to identify these interactions in healthy tissue and diagnose at what level pathological changes can occur, to help combat them. This is where statistical physics comes in.”
The many scales of wound healing
In this multidisciplinary study, the UNIGE physicists collaborated with the team of Professor Steven Brown from the UZH. Using rat epithelial cells, they established flat colonies (2D) in which the cells grow around a silicone insert, subsequently removed to mimic an open lesion. The cell fronts then proliferate to fill the opening and heal the tissue. “We reproduced five possible scenarios by ‘handicapping’ the cells in different ways, in order to see what impact this has on wound healing, i.e. on the speed and roughness of the cell front,” explains Guillaume Rapin, a researcher in Patrycja Paruch’s team. The idea is to see what happens in normal healthy tissue, or when processes such as cell division and communication between neighbouring cells are inhibited, when cell mobility is reduced or when cells are permanently pharmacologically stimulated. “We took some 300 images every four hours for about 80 hours, which allowed us to observe the proliferating cell fronts at very different scales,” continues Guillaume Rapin. “By applying high-performance computational techniques, we were able to compare our experimental observations with the results of numerical simulations,” adds Nirvana Caballero, another researcher in Patrycja Paruch’s team.
Zooming out for greater effect
The scientists observed two distinct roughness regimes: at less than 15 micrometres, below the size of a single cell, and between 80 and 200 micrometres, when several cells are involved. “We have analysed how the roughness exponent evolves over time to reach its natural dynamic equilibrium, depending on the pharmacochemical conditions we have imposed on the cells, and how this roughness increases depending on the scale at which we look,” emphasises Nirvana Caballero. “In a system with a single dominant interaction, we expect to see the same roughness exponent at all scales. Here, we see a changing roughness if we look at the scale of one cell or of ten cells.”
The Geneva and Zurich teams revealed only minor variations in the roughness exponent below 15 micrometres, whatever the conditions imposed on the cell fronts. On the other hand, they found that between 80 and 150 micrometers, the roughness is altered by all pharmacological inhibitors, significantly reducing the roughness exponent. Moreover, they observed that proliferation speed varied greatly between the different pharmacochemical conditions, slowing when cell division and motility were inhibited, and accelerating when cells were stimulated. “More surprisingly, the fastest proliferation speed was achieved when gap-junction communication between cells was blocked,” says Guillaume Rapin. This observation suggests that such communication may be targeted in future therapies, either to promote healing of burns or wounds, or to slow cancer tumour invasion.
These results show that medium-scale interactions play a crucial role in determining the healthy proliferation of a cell front. “We now know at what scale biologists should look for problematic behaviour of cell fronts, which can lead to the development of tumours,” says Nirvana Caballero. Now scientists will be able to focus on these key lenghtscales to probe tumour cells fronts, and directly compare their pathological interactions with this of healthy cells.
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SharecloseShare pageCopy linkAbout sharingimage copyrightGetty ImagesThe EU Commission has recommended easing restrictions on non-essential travel from overseas.Under the plans, anyone who has received the last dose of an EU-approved vaccine at least two weeks beforehand will be permitted to travel.”Time to revive EU tourism industry and for cross-border friendships to rekindle – safely,” EU Commission President Ursula von der Leyen tweeted.The EU currently only allows non-essential travel from seven countries.But the proposals will also contain an “emergency brake” allowing member states to limit travel quickly in response to new variants or a deteriorating health situation in non-EU countries. This would be reviewed every two weeks.Discussions on the plans will begin on Tuesday.The EU has already announced plans for a digital certificate, which would cover anyone who is either vaccinated against Covid-19, has a negative test or has recently recovered.Spain plans to welcome tourists under EU schemeThe passport helping Denmark open up after Covid What are the vaccine passport plans for summer holidays? What do the proposals say?Member states will be able to accept tourists from outside the EU if they have received an approved jab, the European Commission said on Monday, although this could be extended for vaccines that have completed the World Health Organization’s (WHO) emergency use listing process.In addition, children who have not been able to receive a vaccine should be able to travel with their parents as long as they present a negative test, although further testing may be required on arrival.Until the EU-wide pass, known as the digital green certificate, is launched, countries “should be able to accept certificates from non-EU countries based on national law”, the European Commission added. This decision would include “ability to verify the authenticity, validity and integrity of the certificate and whether it contains all relevant data”.The plans will increase also the threshold number of cases in countries from which all travel is allowed – subject to quarantine or testing – from 25 infections per 100,000 people to 100. This, the proposals note, is still far below the EU average of more than 420 per 100,000.The measures will not affect current rules on essential travel or EU citizens and long-term residents and their families.The recommendation will cover all EU member states, apart from Ireland, as well as Iceland, Liechtenstein, Norway and Switzerland. Which vaccines will be accepted?So far, the EU has approved four vaccines: Pfizer-BioNTech, Moderna, Oxford-AstraZeneca and Janssen/Johnson & Johnson. All require two injections for maximum protection, except for the single-dose Janssen/Johnson & Johnson vaccine.The same jabs have been authorised for emergency use by the WHO, with similar approvals for China’s Sinopharm and Sinovac expected in the coming days and weeks.All three vaccines used in the UK – Pfizer-BioNTech, Oxford-AstraZeneca and Moderna – would therefore be covered by the new EU plans.How will certificates be managed?Last week, European lawmakers approved plans for an EU-wide digital pass to restart travel in time for the summer holidays.Key to the certificate is a QR code – a machine-readable graphic code made up of black and white squares – that contains personal data and the EU’s Commission says it will be safe and secure. It is working with the WHO to ensure the certificate is recognised beyond Europe.The 27 member states also want to include non-EU countries such as Norway, Iceland and Switzerland, with officials saying earlier this week that vaccinated travellers from the US may also be able to visit Europe this summer.However, a spokesman for the European Commission said last week that there had been “no contacts” with the UK over the issue. The UK government, which has indicated that foreign travel may resume from 17 May, is working on its own digital system for international travel that would prove travellers’ vaccination status. French lockdown eased to help schools and travelGermany’s Oktoberfest cancelled again over Covid But practical concerns over the EU certificate remain, including questions over how long immunity lasts after an infection and whether further jabs will be needed amid the rapid spread of more contagious Covid variants.Other issues include what data would be used to prove an individual was not infected with coronavirus, privacy concerns and issues recognising information from different countries’ health authorities.What have other countries done?A number of countries have already begun unveiling their own passes as they reopen.In Denmark, the Coronapas app is being used to allow customers who have been vaccinated or recovered from an infection to enter bars, restaurants and museums.A similar scheme in Israel, which has one of the highest levels of vaccinations in the world, permits users to access hotels, gyms and theatres. The “Green pass” has also created travel opportunities for Israeli citizens, following deals with Greece and Cyprus.The International Air Transport Association (IATA), meanwhile, has launched its own app, the IATA Travel Pass, which is being trialled by a number of airlines, including Emirates, Etihad and Qantas.

Over 400 common disinfectants currently in use could be made safer for people and the environment and could better fight the COVID-19 virus with the simple application of UVC light, a new study from the University of Waterloo shows.
Benzalkonium chloride (BAK) is the most common active ingredient in many disinfectants regularly used in hospitals, households, and food processing plants to protect against a wide range of viruses and bacteria — including all strains of SARS-CoV-2, the coronavirus that causes COVID-19 — but its toxicity means that it can’t be used in high concentrations. It also means that products containing BAK are harmful to humans and the environment.
Researchers at Waterloo discovered that the chemical’s toxicity could be fully neutralized using ultraviolet light (UVC) when tested on cultured human corneal cells.
“Our results show that a disinfecting procedure using BAK followed by UVC radiation can minimize the harmful effect of BAK residues on humans and the environment,” said Dr. David McCanna of Waterloo’s Department of Optometry & Vision Science. “Such a procedure also has a great potential to maximize the disinfection efficacy by utilizing two different antimicrobial mechanisms.
“As the pandemic continues, our findings are especially important as it provides another method to make our hospitals, food, homes, and the environment safer.”
While an important ingredient for a disinfectant’s efficacy, BAK is a severe human skin and eye irritant. The chemical’s high toxicity limits the ability to use products with a high concentration of BAK to better protect against harmful viruses and bacteria. High levels of BAK residue are also harmful to the environment, proving especially toxic to fish, aquatic invertebrates, and birds.
After exposing a BAK solution to germicidal ultraviolet-C lamps, they applied the solution to cultured human corneal cells for five minutes and analyzed for cell metabolic activity and viability. The BAK solutions were completely neutralized by UVC as the solutions no longer harmed the cultured human corneal epithelial cells.
“With concerns about the spread of COVID-19, people are utilizing products with BAK as an active ingredient more than ever,” said Waterloo alumnus and lead author Dr. Manlong Xu, who is currently a clinical research fellow in the University of Alberta’s Department of Ophthalmology and Visual Science.
“For many industries, there is the demand to improve the efficacy of standard disinfection procedures, while also keeping in mind any potential negative impact on the environment.”
The study, Neutralization of the eye and skin irritant benzalkonium chloride using UVC radiation, authored by Waterloo’s Faculty of Science’s Dr. McCanna and Dr. Jacob Sivak and Dr. Xu was recently published in the journal Cutaneous and Ocular Toxicology.
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Las rutinas y rituales siempre me protegieron del caos. Cuando llegó la pandemia y todo se trastocó, me propuse reactivarlas.Este artículo forma parte de una serie sobre la resiliencia en tiempos difíciles: lo que podemos aprender de las historias y las experiencias personales.Me despidieron en diciembre. No puedo decir que no lo esperaba. Todo se estaba desmoronando en todas partes, incluido el mundo de los medios de comunicación, pero cuando ocurrió, lo primero que me preocupó —antes que las dudas sobre cómo ganaría dinero o qué haría con el seguro— fue si me quedaría sin la rutina que había desarrollado, perdido y que luego me costó tanto trabajo recuperar.Todos teníamos nuestras rutinas antes de la pandemia y muchas de ellas se vieron alteradas. Casi todas las rutinas personales, si no se interrumpieron por completo, cambiaron de alguna manera, de lo mundano a lo esencial. El hombre mayor que solía ver saboreando lentamente un café expreso todos los días en la cafetería tuvo que pedirlo en un vaso para llevar y beberlo afuera. Hasta que llegó el confinamiento, un amigo iba al centro a ver a sus padres todos los domingos por la mañana, pero tuvo que dejar de hacerlo. Los niños dejaron de asistir a la escuela y gran parte de los trabajadores dejaron de acudir a las oficinas. Tratar de mantener una rutina ya era bastante difícil cuando parecía que el mundo se iba a desmoronar; tratar de establecer rutinas nuevas sin ninguna indicación clara de lo que deparaba el futuro parecía francamente imposible.La vida es una serie de rutinas. Nos acostamos, nos levantamos, trabajamos, jugamos, pero para algunos, las rutinas y los rituales nos ayudan a funcionar contra el caos del mundo y, en muchos casos, de nuestra mente. Algunas mentes no están hechas para las rutinas; por eso he tenido que esforzarme más y disciplinarme para vivir y trabajar de una manera determinada.De niño crecí en una incertidumbre constante, gracias a una vida familiar inestable, a unos padres que se mudaban frecuentemente y, a partir de los 16 años, a no tener un hogar propio. El trauma de esas experiencias empezó a apoderarse de mí, me desgastó y se mezcló con mis diagnósticos de trastorno por déficit de atención e hiperactividad, depresión y trastorno obsesivo-compulsivo de la personalidad, lo que hacía casi imposible que pudiera concentrarme, trabajar y, en general, ser productivo y feliz a diario.En algún momento, por casualidad, empecé a darme cuenta de que cuanto más ponía límites y horarios —levantarme, comer y meditar a horas específicas, hacer ejercicio y anotar el programa del día siguiente—, no solo aumentaba mi sensación de control, sino también de felicidad. Al establecer rutinas para mí, pude protegerme del caos.“Te ayuda a sentir que tienes el control”, dijo en una entrevista Charles Duhigg, autor de El poder del hábito. “Te ayuda a recordar cómo hacer cosas que —quizá por tu trastorno por déficit de atención e hiperactividad— olvidarías debido a la memoria a corto plazo”. En su libro, Duhigg explora la especie de ouróboro —el antiguo símbolo de una serpiente que se come su propia cola— que estaba realizando conmigo mismo. Necesitaba algún tipo de señal, una rutina y luego una recompensa. No había pensado en las recompensas como parte del proceso, pero son esenciales.Pensaba que la recompensa para mí era la tranquilidad. Lo que no sabía es que también me daba otros pequeños trofeos: si iba al gimnasio cinco días a la semana, había una vocecita en mi cabeza que decía: “Te has ganado dos porciones de pizza”. Cuando limpiaba la casa el domingo por la mañana, siempre me abría una cerveza por la tarde. Y a veces ni siquiera eres consciente de las recompensas que te das a ti mismo por la rutina, y creo que esas son las más importantes. Con esas recompensas, estoy siendo bueno conmigo mismo, diciéndome que he hecho algo, así que me he ganado algo.“Te obligas a anticipar las recompensas”, dice Duhigg. “Todo eso es muy bueno”.Para Esmé Weijun Wang, autora de la colección de ensayos The Collected Schizophrenias, “las rutinas y los rituales son una parte fundamental para mantener mi salud mental”, me dijo. Las rutinas de Wang incluyen “mi agenda analógica, en la que escribo un diario, gestiono mis citas y apunto las tareas, que, junto con una serie de otros cuadernos y carpetas, organizan las cosas de manera que la vida se sienta menos abrumadora”.Igualmente importante —y quizá más difícil— es mantener las rutinas. Así que, aunque anotar las citas es importante, recordarme a mí mismo que debo levantarme a una hora determinada, meditar, mi trabajo de la 1 p.m. y mi pausa para llamar por teléfono son actos que me recuerdan dónde van a estar las aguas tranquilas en lo que podría resultar ser un mar agitado.“Cuando cambias un hábito en tu vida que antes considerabas importante”, dijo Duhigg, “solo tienes que ser consciente de cómo cambias ese hábito deliberadamente”.No obstante, en ocasiones las fuerzas externas desbordan la capacidad de mantenerse. Tras cinco años de rutinas constantes, llegó la pandemia. El primer día que trabajé desde casa, mi rutina se vino abajo. Nos dijeron que sería durante una semana, luego dos, después el mes que viene, luego a finales del verano y luego quizás después del Día de Acción de Gracias. Tarde o temprano, volveríamos a la oficina, probablemente. Empecé a dormir hasta más tarde; cuando el gimnasio cerró, tuve que buscar una nueva manera de hacer ejercicio, y como cada cosita que había considerado parte de un día normal para mí empezó a desaparecer, no me di cuenta de cuán deprimido estaba.Para cuando empecé a salir de mi depresión y a darme cuenta de que iba a tener que aprender a adaptarme, ya era otoño. Todavía no había una oficina o un gimnasio o un lugar al que pudiera ir para ver a la gente en persona y conversar con ella con medidas de seguridad. Evité a mi terapeuta durante meses porque me sentía incómodo tomando las sesiones por Zoom. De vez en cuando me saltaba la meditación matutina. Abría y me comía una bolsa de papas fritas en pocos minutos. Era el tipo de espiral que creía haber descubierto cómo corregir.Entonces, una mañana, saqué uno de mis diarios viejos para ver qué había hecho bien en el pasado. Tenía notas sobre lo que funcionaba en mi rutina y lo que no, sobre cómo beber café a ciertas horas me hacía sentir más ansioso o sobre cómo consultar Twitter antes de las 8 de la mañana casi siempre me ponía de mal humor. Me había dejado pequeños recordatorios por si me perdía en el camino.Un día, salí a pasear a mi perro y decidí, sin motivo alguno, que la banda sonora de esa mañana sería Ambient 1/Music for Airports de Brian Eno, un álbum que el compositor escribió y grabó para ayudar a calmar a los viajeros ansiosos. Decidí que caminaría durante toda la primera pista —17 minutos y 22 segundos— antes de volver a casa. Estaba haciendo algo que hacía todas las mañanas, pero al dar vuelta en una esquina, me di cuenta de que también me estaba preparando para el día y sentí una comodidad que no había sentido en meses. Los bucles musicales de Eno sin letras y con ritmos de piano simplemente sirvieron como ruido de fondo para mi meditación a pie no planificada y como recordatorio de cuán necesaria era.Fue entonces cuando empecé a restablecer mi rutina. Al cabo de una semana, volví a tener una especie de horario normal para levantarme, sacar al perro a pasear y permitirme revisar Instagram. Estaba llegando a un punto tan cómodo como es posible estar durante una pandemia. Entonces, recibí el mensaje a través de Slack de que me necesitaban para una reunión con una persona de Recursos Humanos. Sabía lo que iba a ocurrir a continuación.Evidentemente, estaba sintiendo todo eso que uno siente cuando pierde un trabajo. Era doloroso. Mis finanzas iban a sufrir un golpe. El único canal de comunicación que tenía con alguien, además de mi esposa, se había cortado, pero me di cuenta de que no podía hacer nada más que levantarme y empezar a preparar mi agenda para el día siguiente. El día de mañana, y todos los días posteriores, mi rutina y mis rituales estaban solo en mis manos. Y eso no me lo podía quitar nadie.El libro más reciente de Jason Diamond es The Sprawl.

Customised medicines could one day be manufactured to patients’ individual needs, with University of East Anglia (UEA) researchers investigating technology to 3D ‘print’ pills.
The team, including Dr Andy Gleadall and Prof Richard Bibb at Loughborough University, identified a new additive manufacturing method to allow the 3D printing of medicine in highly porous structures, which can be used to regulate the rate of drug release from the medicine to the body when taken orally.
Dr Sheng Qi, a Reader in Pharmaceutics at UEA’s School of Pharmacy, led the research. The project findings, ‘Effects of porosity on drug release kinetics of swellable and erodible porous pharmaceutical solid dosage forms fabricated by hot melt droplet deposition 3D printing’, are published today in the International Journal of Pharmaceutics.
Dr Qi said: “Currently our medicines are manufactured in ‘one-size-fits-all’ fashion.
“Personalised medicine uses new manufacturing technology to produce pills that have the accurate dose and drug combinations tailored to individual patients. This would allow the patients to get maximal drug benefit with minimal side effects.
“Such treatment approaches can particularly benefit elderly patients who often have to take many different types of medicines per day, and patients with complicated conditions such as cancer, mental illness and inflammatory bowel disease.”
The team’s work, Dr Qi said, is building the foundation for the technology needed in future to produce personalised medicine at the point-of-care. She said 3D printing has the unique ability to produce porous pharmaceutical solid dosage forms on-demand.
Pharmaceutical 3D printing research is a new research field that has rapidly developed in the past five years. Most commonly used 3D printing methods require the drug being processed into spaghetti-like filaments prior to 3D printing.
The team investigated a newly developed 3D printing method that can rapidly produce porous pharmaceutical tablets without the use of filaments. The results revealed that by changing the size of the pores, the speed of a drug escaping from the tablet into the body can be regulated.
Further research will be required in order to use the porosity to tailor the dose and dosing frequency (i.e. once daily or twice daily) of medicine to each patient’s needs, and use this principle to build multiple medicines into a single daily poly-pill for patients who are on a complex medicine regiment.
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Volunteer firefighters — who comprise more than 65 percent of the U.S. fire service — have higher levels of “forever chemicals,” per- and polyfluoroalkyl substances (PFAS), in their bodies than the general public, according to a Rutgers study.
The study, which was published in the International Journal of Environmental Research and Public Health, compared the levels of nine PFAS chemicals in the blood of volunteer firefighters against levels in the general population.
It is the first study to evaluate volunteer firefighters’ exposure to PFAS, which are chemicals that accumulate in human bodies and in the environment and are found in everyday items like electronics and carpeting. PFAS have been associated with numerous health conditions that impact firefighters, including cardiovascular disease. Increasing evidence has linked them to cancer.
“The primary cause of line-of duty death among firefighters are heart attacks. They also get and die from many types of cancer more often than other people,” said lead author Judith Graber, an associate professor at Rutgers School of Public Health and a faculty member at the Environmental and Occupational Health Sciences Institute. “More than 95 percent of the U.S. population have these chemicals to some degree in their bodies, but firefighters have heightened exposure to PFAS through their protective gear and fire suppression foam and the burning materials they encounter that release particles, which can be inhaled or settle on gear and skin.”
The study surveyed 135 members of a volunteer fire department in New Jersey on their lifestyle and cancer risk factors and compared traces of nine PFAS chemicals in their blood against the levels recorded in the general population in the Centers for Disease Control and Prevention’s National Health and Nutrition Examination Survey, which tracks the health status of a nationally representative sample of 5,000 people annually. Although there are more than 4,000 PFAS chemicals, the study looked at the nine chemicals that the CDC has tracked the longest and are most often seen in the general population.
The researchers found that the levels of two of the chemicals studied — perfluorododecanoic acid (PFDoA) and perfluorodecanoic acid (PFDA) — were higher in volunteer firefighters. “Notably, we found PFDoA levels in 80 percent of the firefighters, but little in the general public,” Graber said.
Higher chemical levels also were associated with the number of years of firefighting; the average participant had 20 years of experience. Since they are always on call, volunteer firefighters could potentially accumulate more years of firefighting-related exposures than their career counterparts, Graber said.
“The number one risk of a firefighter is being protected from the fire. The chemicals used in fire suppression foam and the protective clothing firefighters use came out 40 years ago when people thought they were safe, and they work well for what they are intended to do,” Graber said. “Further research is needed to better understand the sources of these chemicals and to design effective foam and protective clothing that do not use these chemicals.”
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The process of acceptance and letting go builds the resilience necessary to navigate an array of life’s obstacles.This article is part of a series on resilience in troubled times — what we can learn about it from history and personal experiences.It’s been three months, and I still fight back tears when I’m reminded of the death of my Labrador retriever, Zena. The haunting image of finding her lying on the kitchen floor flashes back: her jaw clenched, eyes open and body lifeless but warm.She was nearly 13, but there were no signs she was in distress when I left her 20 minutes earlier. Yet she was gone. I felt as if I let her down in some way. I wasn’t there for her.When Zena was just a few months old, she curled up on the bed with my 88-year-old father, as I held his hand, and he softly exhaled his last breath. My younger brother, Jack, died unexpectedly three years ago. I clung to Zena for comfort.My first experience with death was losing my turtles, Charlie and Tina, at 6. I’ve since lost friends, relatives, other dogs, cats, horses. Decades later, Zena’s death has sharply reminded me how aching grief is.Our pets are a part of the everyday fabric of our lives in a way that few human relationships are. When you lose one that is close to you, something inside shifts.And yet the death of a family pet can remind us of how vulnerable, precarious and precious life is. It’s that process of acceptance and letting go that builds the resilience necessary to navigate an array of life’s obstacles. We hone an ability to adapt to the evanescence of our lives with grace and hope.“We’re changed and transformed by the loss,” said Leigh Chethik, a clinical psychologist in Chicago. “It brings impermanence and death into an updated internal, emotional map. This loss can help us with whatever comes next, whatever future losses may be in store. We come to see that we can create a new understanding and attach to new dreams.” Below are some ways in which the loss of a beloved pet can be a catalyst for personal growth.Embracing Your Loss“The idea that grief can often be the price of love is helpful in developing resilience,” according to Jessica Harvey, a psychotherapist in Portland, Ore., who specializes in pet grief. “By focusing on the positive elements of having a pet as the cause of why the hurt is so powerful when they are gone, we can begin to heal.”Pets occupy a unique role in our lives. “They are usually our ‘roommates,’ part of the household, and they are typically a source of pure warmth and positive experience,” Ms. Harvey said. “How we are able to manage the temporary reduction of joy and warmth from the missing roommate can be a significant practice in resilience.”That loss, of course, can have a startling depth. “For adults in their upper-20s to mid-30s it’s like losing their innocence as a new adult and being catapulted into reality,” said Dani McVety, a veterinarian and a founder of Lap of Love Veterinary Hospice, a national network of veterinarians dedicated solely to end of life care. “Many times, people in this age range got their dog or cat at the very beginning of their adulthood. This pet has witnessed them go through college, boyfriends or girlfriends, marriage, children, career developments, and so on. This pet has been the one constant in their life through their biggest growth years.”How we handle the death of a pet “shapes how we deal with love and loss, conjoined emotions,” said Kaleel Sakakeeny, a pet loss and bereavement counselor who is based in Boston.From Grief, Building ConfidenceBut how does that growth happen? One study, “Post-Traumatic Growth Following the Loss of a Pet,” conducted by Wendy Packman and others, of the Pacific Graduate School of Psychology at Palo Alto University, found that after losing a beloved pet, many of the participants reported an improved ability to relate to others and feel empathy for their problems, an enhanced sense of personal strength, and a greater appreciation of life.Lynn Harrington, who lives in The Plains, Va., lost her 15-year-old Norwich terrier, Hap, about a year ago. “For many months, I couldn’t shake the sadness,” Ms. Harrington said. “And during these sad times, I finally remembered a lesson I learned many years ago with the loss of my first dog: Animals that come into our lives are gifts to us and can never be replaced. However, another animal can come to us and help us heal our hearts.”Shortly after that epiphany, a friend told her about a senior dog that needed a home, and a match was made. “There isn’t a day that I don’t think of Hap through a photo, a memory shared, or even some funny mannerism I see of him in my rescue dog,” Ms. Harrington said. “These moments remind me that I’m grateful for the animals in my life — they teach me about love and that I’m resilient even in times of great challenge or sadness.”Remembrance itself — though photos and memorials — can be healing. “Grief is ongoing,” Ms. Packman said. “Remaining connected to your beloved pet after death can facilitate the bereaved’s ability to cope with loss and the accompanying changes in their lives. Our findings suggest that those who derive comfort from continuing bonds — holding onto possessions and creating memorials for their pet — may be more likely to experience post-traumatic growth.”Life Lessons for Children …For children, the loss of a pet can be “a dress rehearsal for losing a human family member,” Dr. Chethik said. “With the death of a pet, kids are often exposed to a new existential crisis or struggle: the idea of impermanence and mortality. Things we love and care for are not around forever. We can and will lose what and who we love. And we can’t go where we may typically go for comfort — to our pet.”For children, this process can be hard to grasp. The death of a family pet can trigger a sense of grief in children that is deep and lingering and that can possibly lead to subsequent mental health issues, according to a new study by researchers at Massachusetts General Hospital.“The impact can be traumatic,” wrote Katherine Crawford, the lead author of the paper. “We found this experience of pet death is often associated with elevated mental health symptoms in children, and that parents and physicians need to recognize and take those symptoms seriously, not simply brush them off.”Dr. Chethik added: “A child needs to actively grieve and process the loss,” he said. “The attention, support, honesty, sharing and understanding the child receives during this time of grief will them create an emotional template for the human losses that will inevitably come their way.”With support from parents and others, the loss of a pet can be a way for children to move forward. “Teaching children how to say goodbye and that the difficult emotions that accompany grief are OK to feel is a powerful lesson,” Ms. Harvey said. “Children learn that this painful experience does start to feel better eventually, and that other difficult situations in the future can as well.”… And for AdultsI’ve reminded myself these past months not to rush the process. Grief slides from the heart in its own time. I’m still talking to Zena and reflexively looking for her when I wake up in the morning. Yet, I know that soon my husband and I will be ready for a next chapter with a new companion.This is the second dog we’ve lost during our marriage. We’ve grappled with the sadness each time, but we both know from experience that the love and laughter a pet brings into our lives are worth it.As Ms. Harrington said, “Just knowing I can move through that kind of pain and get to the other side really does translate into that lesson that even when things in other parts of my life seem dark, I just need to keep moving through it and the unexpected can happen, bringing joy or opportunity.”

The younger the age at diagnosis for Type 2 diabetes, the higher the risk for Alzheimer’s disease and other forms of dementia years later.Type 2 diabetes is a chronic, progressive illness that can have devastating complications, including hearing loss, blindness, heart disease, stroke, kidney failure and vascular damage so severe as to require limb amputation. Now a new study underscores the toll that diabetes may take on the brain. It found that Type 2 diabetes is linked to an increased risk for Alzheimer’s disease and other forms of dementia later in life, and the younger the age at which diabetes is diagnosed, the greater the risk.The findings are especially concerning given the prevalence of diabetes among American adults and rising rates of diabetes in younger people. Once referred to as “adult-onset diabetes” to distinguish it from the immune-related “juvenile-onset” Type 1 disease that begins in childhood, Type 2 diabetes is seen in younger and younger people, largely tied to rising rates of obesity. The Centers for Disease Control and Prevention estimates that more than 34 million American adults have Type 2 diabetes, including more than a quarter of those 65 and over. About 17.5 percent of those aged 45 to 64 have Type 2 disease, as do 4 percent of 18- to 44-year-olds.“This is an important study from a public health perspective,” said the director of the Yale Diabetes Center, Dr. Silvio Inzucchi, who was not involved in the research. “The complications of diabetes are numerous, but the brain effects are not well studied. Type 2 diabetes is now being diagnosed in children, and at the same time there’s an aging population.”For the new study, published in JAMA, British researchers tracked diabetes diagnoses among 10,095 men and women who were 35 to 55 at the start of the project, in 1985 to 1988, and free of the disease at the time.They followed them with clinical examinations every four or five years through 2019. At each examination, the researchers took blood samples to evaluate fasting glucose levels, a measure used to detect diabetes, and recorded self-reported and doctor-diagnosed cases of Type 2 disease.The researchers also determined dementia cases using British government databases. Over an average follow-up of 32 years, they recorded 1,710 cases of Type 2 diabetes and 639 of dementia.The researchers calculated that each five-year earlier onset of diabetes was associated with a 24 percent increased risk of dementia. Compared with a person without diabetes, a 70-year-old diagnosed with Type 2 diabetes less than five years earlier had an 11 percent increased risk for dementia. But a diagnosis at age 65 was associated with a 53 percent increased risk of later dementia, and a diagnosis at 60 with a 77 percent increased risk. A person diagnosed with Type 2 at ages 55 to 59 had more than twice the risk of dementia in old age compared with a person in the same age group without diabetes.The study was observational, so could not prove that diabetes causes dementia. But it was long-running, with a large study population. The researchers controlled for many factors that affect the risk for dementia, including race, education, heart conditions, stroke, smoking and physical activity, and the diabetes-dementia link persisted.“These are exceptional data,” said Daniel Belsky, an assistant professor of epidemiology at Columbia Mailman School of Public Health who was not involved in the research. “These associations between the timing of onset of diabetes and development of dementia show the importance of a life-course approach to preventing degenerative disease.“We are an aging population, and the things we fear most are degenerative diseases like dementia, for which we have no cures, no therapies, and very few modifiable pathways to target for prevention,” Dr. Belsky said. “We can’t wait until people are in their 70s.”Why diabetes would be linked to dementia is unknown. “We can speculate on the mechanisms,” said the study’s senior author, Archana Singh-Manoux, a research professor at INSERM, the French national health institute. “Living a long time with diabetes and having hypoglycemic events is harmful, and there are neurotoxic effects of diabetes as well. The brain uses enormous amounts of glucose, so with insulin resistance, the way the brain uses glucose might be altered” in people with Type 2 diabetes.Type 2 can be managed and its complications reduced by monitoring blood sugar and conscientiously following a well-designed, personalized program of medication, exercise and diet. Is it possible that such a routine could minimize the risk for dementia later in life?“With better control, there was less cognitive decline than in those with poor control,” Dr. Singh-Manoux said. “So stick to your medication. Look after your glycemic markers. That’s the message for people who have diabetes.”

Widely circulating coronavirus variants and persistent hesitancy about vaccines will keep the goal out of reach. The virus is here to stay, but vaccinating the most vulnerable may be enough to restore normalcy.Early in the pandemic, when vaccines for the coronavirus were still just a glimmer on the horizon, the term “herd immunity” came to signify the endgame: the point when enough Americans would be protected from the virus so we could be rid of the pathogen and reclaim our lives.Now, more than half of adults in the United States have been inoculated with at least one dose of a vaccine. But daily vaccination rates are slipping, and there is widespread consensus among scientists and public health experts that the herd immunity threshold is not attainable — at least not in the foreseeable future, and perhaps not ever.Instead, they are coming to the conclusion that rather than making a long-promised exit, the virus will most likely become a manageable threat that will continue to circulate in the United States for years to come, still causing hospitalizations and deaths but in much smaller numbers.How much smaller is uncertain and depends in part on how much of the nation, and the world, becomes vaccinated and how the coronavirus evolves. It is already clear, however, that the virus is changing too quickly, new variants are spreading too easily and vaccination is proceeding too slowly for herd immunity to be within reach anytime soon.Continued immunizations, especially for people at highest risk because of age, exposure or health status, will be crucial to limiting the severity of outbreaks, if not their frequency, experts believe.“The virus is unlikely to go away,” said Rustom Antia, an evolutionary biologist at Emory University in Atlanta. “But we want to do all we can to check that it’s likely to become a mild infection.”The shift in outlook presents a new challenge for public health authorities. The drive for herd immunity — by the summer, some experts once thought possible — captured the imagination of large segments of the public. To say the goal will not be attained adds another “why bother” to the list of reasons that vaccine skeptics use to avoid being inoculated.Yet vaccinations remain the key to transforming the virus into a controllable threat, experts said.Dr. Anthony S. Fauci, the Biden administration’s top adviser on Covid-19, acknowledged the shift in experts’ thinking.“People were getting confused and thinking you’re never going to get the infections down until you reach this mystical level of herd immunity, whatever that number is,” he said.“That’s why we stopped using herd immunity in the classic sense,” he added. “I’m saying: Forget that for a second. You vaccinate enough people, the infections are going to go down.”Why reaching the threshold is toughCrowds on the National Mall in April. Resistance to the vaccines is a main reason the United States is unlikely to reach herd immunity, but it is not the only one.Amr Alfiky/The New York TimesOnce the novel coronavirus began to spread across the globe in early 2020, it became increasingly clear that the only way out of the pandemic would be for so many people to gain immunity — whether through natural infection or vaccination — that the virus would run out of people to infect. The concept of reaching herd immunity became the implicit goal in many countries, including the United States.Early on, the target herd immunity threshold was estimated to be about 60 to 70 percent of the population. Most experts, including Dr. Fauci, expected that the United States would be able to reach it once vaccines were available.But as vaccines were developed and distribution ramped up through the winter and into the spring, estimates of the threshold began to rise. That is because the initial calculations were based on the contagiousness of the original version of the virus. The predominant variant now circulating in the United States, called B.1.1.7 and first identified in Britain, is about 60 percent more transmissible.As a result, experts now calculate the herd immunity threshold to be at least 80 percent. If even more contagious variants develop, or if scientists find that immunized people can still transmit the virus, the calculation will have to be revised upward again.Polls show that about 30 percent of the U.S. population is still reluctant to be vaccinated. That number is expected to improve but probably not enough. “It is theoretically possible that we could get to about 90 percent vaccination coverage, but not super likely, I would say,” said Marc Lipsitch, an epidemiologist at the Harvard T.H. Chan School of Public Health.Though resistance to the vaccines is a main reason the United States is unlikely to reach herd immunity, it is not the only one.Herd immunity is often described as a national target. But that is a hazy concept in a country this large.“Disease transmission is local,” Dr. Lipsitch noted.“If the coverage is 95 percent in the United States as a whole, but 70 percent in some small town, the virus doesn’t care,” he explained. “It will make its way around the small town.”Uneven Willingness to Get Vaccinated Could Affect Herd ImmunityIn some parts of the United States, inoculation rates may not reach the threshold needed to prevent the coronavirus from spreading easily.

NHS workers at Wales’ largest hospital are creating a woodland to offset the carbon emissions and waste that came from the machines needed to treat patients with Covid-19.Staff on the critical care unit at the University Hospital of Wales in Cardiff say they hope their woodland in Crickhowell inspires other hospital trusts and industries to do the same.The woodland will be given a Welsh name and should be open to the public later this year.Video Journalist: Laura Foster