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Why are rubies red and emeralds green? Their colors come from the same metal in their atomic structure

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theconversation.com – Daniel Freedman, Dean of the College of Science, Technology, Engineering, Mathematics & Management, University of Wisconsin-Stout – 2025-02-04 07:42:00

Why are rubies red and emeralds green? Their colors come from the same metal in their atomic structure

Rubies get their bright color from some fascinating chemistry.
Matthew Hill/Bloomberg Creative Photos via Getty Images

Daniel Freedman, University of Wisconsin-Stout

The colors of rubies and emeralds are so striking that they define shades of red and green – ruby red and emerald green. But have you ever wondered how they get those colors?

I am an inorganic chemist. Researchers in my field work to understand the chemistry of all the elements that make up the periodic table. Many inorganic chemists focus on the transition metals – the elements in the middle of the periodic table. The transition metals include most of the metals you are familiar with, like iron (Fe) and gold (Au).

One feature of compounds made with transition metals is their intense color. There are many examples in nature, including gemstones and paint pigments. Even the color of blood comes from the protein hemoglobin, which contains iron.

Investigating the colors of compounds containing transition metals leads you into some really amazing science – that’s part of what drew me to study this field.

Rubies and emeralds are great examples of how a small amount of a transition metal – in this case, chromium – can create a beautiful color in what would otherwise be a fairly boring-looking mineral.

Minerals and crystals

A small, round ruby
Rubies appear red because they absorb blue and green light.
benedek/E+ via Getty Images

Both rubies and emeralds are minerals, which is a type of rock with a consistent chemical composition and a highly ordered structure at the atomic level.

When this highly ordered structure extends in all three dimensions, the mineral becomes a crystal.

With a theory developed by physicists in the 1920s called crystal field theory, scientists can explain why rubies and emeralds have the colors they do. Crystal field theory makes predictions about how a transition metal ion’s structure is affected by the other atoms surrounding it.

Rubies are mainly made up of the mineral corundum, which is composed of the elements aluminum and oxygen in a regular, repeating array. Each aluminum ion is surrounded by six oxygen ions.

A chemical structure diagram showing
A crystal of corundum looks like this at the atomic level, with the aluminum ions shown as red balls and the oxygen ions shown as white balls. Each aluminum ion is surrounded by six oxygen ions, and each oxygen by four aluminums.
Eigenes Werk/Wikimedia Commons, CC BY-SA

Emeralds are mainly made up of the mineral beryl, which is made from the elements beryllium, aluminum, silicon and oxygen. Beryl’s crystal structure is more complicated than corundum’s because of the additional elements in the formula, but each aluminum ion is again surrounded by six oxygen ions.

A rectangular emerald
Emeralds appear green because they absorb red and blue light.
SunChan/E+ via Getty Images

Pure corundum and beryl are colorless. The brilliant colors of rubies and emeralds come from the presence of very small amounts of chromium. The chromium replaces about 1% of the aluminum in the corundum or beryl crystal when a ruby or emerald forms underground at a high temperature and pressure.

But how can one element – chromium – create the red color of a ruby and green color of an emerald?

Color science

Rubies and emeralds have the colors they do because, like many substances, they absorb some colors of light. Most visible light, like sunlight, is composed of all the colors of the rainbow: red, orange, yellow, green, blue, indigo and violet. These colors make up the visible light spectrum, which is easy to remember as ROY G BIV.

A diagram showing the visible light spectrum, with indigo and violet having shorter wavelengths than red and orange.
Objects absorb some visible light wavelengths and reflect others, which is why we see them as having a color.
Fulvio314/Wikimedia Commons, CC BY-SA

One of the main reasons why objects have a color is because they absorb one or more of these visible colors of light. If a substance absorbs, for instance, red light, it means that the red light gets trapped in the substance and the other colors reflect back to your eyes. The color you see is the sum of the remaining light, which will be in the green-to-blue range. If a substance absorbs blue, it will look red or orange to you.

Unlike the colorless aluminum ion, the chromium ion absorbs blue and green light when surrounded by the oxygen ions. The red light is reflected back, so that’s what you see in rubies.

In an emerald, even though the chromium is surrounded by six oxygen ions, there is a weaker interaction between the chromium and the surrounding oxygen ions. That’s due to the presence of silicon and beryllium in the beryl crystal. They cause the emerald to absorb blue and red light, leaving the green for you to see.

The ability to tune the properties of transition metals like chromium through changing what is surrounding it is a core strategy in my field of inorganic chemistry. Doing so can help scientists understand the basic science of metal-containing compounds and the design of chemical compounds for specific purposes.

You can take delight in the amazing colors of the gemstones, but through chemistry, you can also see how nature creates those colors using an endless variety of complex structures made with the elements in the periodic table.The Conversation

Daniel Freedman, Dean of the College of Science, Technology, Engineering, Mathematics & Management, University of Wisconsin-Stout

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What the ‘moral distress’ of doctors tells us about eroding trust in health care

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theconversation.com – Daniel T. Kim, Assistant Professor of Bioethics, Albany Medical College – 2025-02-04 07:45:00

What the ‘moral distress’ of doctors tells us about eroding trust in health care

Daniel T. Kim, Albany Medical College

I sit on an ethics review committee at the Albany Med Health System in New York state, where doctors and nurses frequently bring us fraught questions.

Consider a typical case: A 6-month-old child has suffered a severe brain injury following cardiac arrest. A tracheostomy, ventilator and feeding tube are the only treatments keeping him alive. These intensive treatments might prolong the child’s life, but he is unlikely to survive. However, the mother – citing her faith in a miracle – wants to keep the child on life support. The clinical team is distressed – they feel they’re only prolonging the child’s dying process.

Often the question the medical team struggles with is this: Are we obligated to continue life-supporting treatments?

Bioethics, a modern academic field that helps resolve such fraught dilemmas, evolved in its early decades through debates over several landmark cases in the 1970s to the 1990s. The early cases helped establish the right of patients and their families to refuse treatments.

But some of the most ethically challenging cases, in both pediatric and adult medicine, now present the opposite dilemma: Doctors want to stop aggressive treatments, but families insist on continuing them. This situation can often lead to moral distress for doctors – especially at a time when trust in providers is falling.

Consequences of lack of trust

For the family, withdrawing or withholding life-sustaining treatments from a dying loved one, even if doctors advise that the treatment is unlikely to succeed or benefit the patient, can be overwhelming and painful. Studies show that their stress can be at the same level as people who have just survived house fires or similar catastrophes.

While making such high-stakes decisions, families need to be able to trust their doctor’s information; they need to be able to believe that their recommendations come from genuine empathy to serve only the patient’s interests. This is why prominent bioethicists have long emphasized trustworthiness as a central virtue of good clinicians.

However, the public’s trust in medical leaders has been on a precipitous decline in recent decades. Historical polling data and surveys show that trust in physicians is lower in the U.S. than in most industrialized countries. A recent survey from Sanofi, a pharmaceutical company, found that mistrust of the medical system is even worse among low-income and minority Americans, who experience discrimination and persistent barriers to care. The COVID-19 pandemic further accelerated the public’s lack of trust.

In the clinic, mistrust can create an untenable situation. Families can feel isolated, lacking support or expertise they can trust. For clinicians, the situation can lead to burnout, affecting quality and access to care as well as health care costs. According to the National Academy of Medicine, “The opportunity to attend to and ease suffering is the reason why many clinicians enter the healing professions.” When doctors see their patients suffer for avoidable reasons, such as mistrust, they often suffer as well.

At a time of low trust, families can be especially reluctant to take advice to end aggressive treatment, which makes the situation worse for everyone.

Ethics of the dilemma

Physicians are not ethically obligated to provide treatments that are of no benefit to the patient, or may even be harmful, even if the family requests them. But it can often be very difficult to say definitively what treatments are beneficial or harmful, as each of those can be characterized differently based on the goals of treatment. In other words, many critical decisions depend on judgment calls.

Consider again the typical case of the 6-month-old child mentioned above who had suffered severe brain injury and was not expected to survive. The clinicians told the ethics review committee that even if the child were to miraculously survive, he would never be able to communicate or reach any “normal” milestones. The child’s mother, however, insisted on keeping him alive. So, the committee had to recommend continuing life support to respect the parent’s right to decide.

Physicians inform, recommend and engage in shared decision-making with families to help clarify their values and preferences. But if there’s mistrust, the process can quickly break down, resulting in misunderstandings and conflicts about the patient’s best interests and making a difficult situation more distressing.

Moral distress in health care.

Moral distress

When clinicians feel unable to provide what they believe to be the best care for patients, it can result in what bioethicists call “moral distress.” The term was coined in 1984 in nursing ethics to describe the experience of nurses who were forced to provide treatments that they felt were inappropriate. It is now widely invoked in health care.

Numerous studies have shown that levels of moral distress among clinicians are high, with 58% of pediatric and neonatal intensive care clinicians in a study experiencing significant moral distress. While these studies have identified various sources of moral distress, having to provide aggressive life support despite feeling that it’s not in the patient’s interest is consistently among the most frequent and intense.

Watching a patient suffer feels like a dereliction of duty to many health care workers. But as long as they are appropriately respecting the patient’s right to decide – or a parent’s, in the case of a minor – they are not violating their professional duty, as my colleagues and I argued in a recent paper. Doctors sometimes express their distress as a feeling of guilt, of “having blood on their hands,” but, we argue, they are not guilty of any wrongdoing. In most cases, the distress shows that they’re not indifferent to what the decision may mean for the patient.

Clinicians, however, need more support. Persistent moral distresses that go unaddressed can lead to burnout, which may cause clinicians to leave their practice. In a large American Medical Association survey, 35.7% of physicians in 2022-23 expressed an intent to leave their practice within two years.

But with the right support, we also argued, feelings of moral distress can be an opportunity to reflect on what they can control in the circumstance. It can also be a time to find ways to improve the care doctors provide, including communication and building trust. Institutions can help by strengthening ethics consultation services and providing training and support for managing complex cases.

Difficult and distressing decisions, such as the case of the 6-month-old child, are ubiquitous in health care. Patients, their families and clinicians need to be able to trust each other to sustain high-quality care.The Conversation

Daniel T. Kim, Assistant Professor of Bioethics, Albany Medical College

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Smart brands rein in ad spending when a rival faces a setback − here’s why

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theconversation.com – Vivek Astvansh, Associate Professor of Quantitative Marketing and Analytics, McGill University – 2025-02-04 07:44:00

Smart brands rein in ad spending when a rival faces a setback − here’s why

When a rival business stumbles, it’s both a threat and an opportunity.
Matt Molloy via Getty Images Plus

Vivek Astvansh, McGill University

Imagine: You’re in charge of marketing for a major automaker, and your biggest competitor just recalled thousands of vehicles. Now customers are worried about the safety of cars like yours. Do you seize the moment and ramp up advertising to steal market share? Or do you pull back on ads, fearing that customers will connect your brand with the bad press?

For what marketing professors like me call “substitute brands,” this sort of dilemma pops up all the time. Whether it’s a product recall, a customer data breach or a scandal, bad news for one brand can shake customers’ confidence in an entire product category.

The big question: Should competitors respond by increasing or decreasing their advertising? And will these adjustments help or hurt sales?

At first glance, the answer might seem obvious. More ad spending should mean bigger market share, right? But the reality is more complex. In a recent study looking at how 62 car brands responded to a 2014 recall, my colleagues and I found that, on average, when a rival brand issues a recall, its competitors cut their ad spending in half. In other words, most brands treat a rival’s crisis as a threat rather than an opportunity.

And when we looked at the ads’ content, we saw something even more interesting. When a rival brand stumbled, we found substitutes boosted their price-focused advertising by 25% on average, likely in an attempt to attract deal seekers. At the same time, they cut quality-focused advertising by 71%, possibly to avoid drawing unwanted comparisons.

And here’s the kicker: This strategy works.

We found, on average, a rival’s recall raises a substitute’s monthly sales by 35.3% – and the more a brand pulls back on ad spending, the greater the effect. So, when a competitor falters, the best response isn’t necessarily to shout louder. Instead, the data suggests a smarter play: Spend strategically, focus on price messaging, and avoid drawing attention to quality comparisons.

How we did our work

To understand how brands respond when a competitor faces a crisis, we focused on a real-world case: Volkswagen’s recall of nearly half a million cars branded under the Sagitar model in October 2014. This provided the perfect opportunity to study how rival brands adjusted their advertising strategies.

We identified Sagitar’s substitute models – 62 other sedans in the A-class category, sold by more than 30 manufacturers – and collected data on sales and ad spending across 308 media markets in the months before and after the recall. We then did a statistical analysis, controlling for several other variables that could influence ad spending.

Why it matters

Prior research offers mixed guidance on how a substitute brand should adjust its ad spending after a rival’s marketing crisis. Anecdotal evidence from the automotive and consumer goods industries is also mixed. For example, after Samsung recalled its Galaxy Note 7 in 2016 due to faulty batteries, competing phonemakers aggressively ramped up their advertising in an attempt to increase their market share.

Similarly, in 2010, after a Toyota recall, General Motors offered incentives for Toyota owners to switch to a GM car. GM’s chief marketing officer positioned these incentives as GM’s way to meet car buyers’ desire for peace of mind, and reports suggest that GM’s and other rival carmakers’ sales increased following Toyota’s recall.

But my team’s research suggests that this sort of strategy might not be the best one. Sometimes, saying less actually says more.

The Research Brief is a short take on interesting academic work.The Conversation

Vivek Astvansh, Associate Professor of Quantitative Marketing and Analytics, McGill University

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Some viruses prefer mosquitoes to humans, but people get sick anyway − a virologist and entomologist explain why

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theconversation.com – Lee Rafuse Haines, Associate Research Professor of Molecular Parasitology and Medical Entomology, University of Notre Dame – 2025-02-04 07:44:00

Some viruses prefer mosquitoes to humans, but people get sick anyway − a virologist and entomologist explain why

The Aedes mosquito is a vector of several viral diseases, including eastern equine encephalitis, or EEE, and West Nile fever.
Lee Haines, CC BY-ND

Lee Rafuse Haines, University of Notre Dame and Pilar Pérez Romero, University of Notre Dame

Humans have an exceptional ability to deal with viruses. In most cases, your immune system is able to fight an infection. On the other hand, your body provides a spa-like environment that is temperate and stable, optimal for viruses to replicate. Human behavior, including close contact with animals and frequent travel, also increases the likelihood of becoming infected.

From the perspective of viruses spread by insects, or arboviruses, making the evolutionary leap from insects to humans is a tough battle. Viruses cannot replicate very well in humans, which means transmission from mosquitoes is often very difficult.

One might think arboviruses continually evolve in ways that enable them to infect more species. But do they?

We are a virologist and an entomologist who study insect-borne and viral diseases and how human and insect immune systems respond to invading pathogens. Our work provides insights on the complex journey of an arbovirus as it cycles between insect and vertebrate hosts.

As an example, let’s use a Togavirus, the mosquito-transmitted arbovirus that causes eastern equine encephalitis, or EEE. This rare but serious disease can cause a potentially fatal neurological condition in humans and horses. Although EEE is primarily endemic to the eastern United States, its incidence in recent years has increased in regions farther north, with several reported cases in states such as Michigan, Massachusetts and New York.

While rare, a EEE infection in people can lead to severe complications or death.

From animals to mosquitoes

A female mosquito’s inner workings – particularly its guts and salivary glands – create the perfect environment for a virus to flourish.

When a mosquito bites an infected nonhuman host, such as a sick bird, the virus is transported with freshly ingested blood into the mosquito’s midgut – the equivalent to the human stomach and intestines where food is stored and digested. The virus quickly infects midgut cells to avoid a hostile digestive environment and quietly replicates without activating the mosquito’s immune pathways.

Within days, the virus will be released by damaged midgut cells to migrate to the mosquito’s salivary glands, where it will be positioned for transmission. Now, each time the mosquito feeds, it will pump virus-saturated saliva into its new animal host and continue the disease transmission cycle.

Microscopy image of oblong blobs filled with small red circles, surrounded by blue cicular blobs
This image shows a tissue section of the salivary gland of a mosquito infected with EEE. The virus particles are colored red.
Fred Murphy and Sylvia Whitfield/CDC

It is easy for the virus to avoid detection by the mosquito’s relatively primitive immune system. Compared with humans, the immune system of mosquitoes can launch only a generalized and overall less effective attack on pathogens. This means an arbovirus can usually establish a persistent, lifelong, almost symbiotic infection without damaging the mosquito’s health, perfect for the virus to disseminate itself.

Mosquitoes have evolved over millions of years to become tolerant to arboviral infections. This relationship has allowed the mosquito to maintain viral populations without having to launch energy-expensive immune responses. However, this does not mean mosquitoes are just passive virus carriers. An arbovirus can change how infected mosquitoes behave or reproduce.

For example, viruses can manipulate mosquitoes in two ways: by making them feed more frequently, and by increasing their attraction to infected hosts. However, this behavior puts the mosquito at greater risk of being killed by irritated hosts who notice the repeated biting attempts. Arboviruses can also affect mosquito reproduction by sometimes reducing the number of eggs a female mosquito produces and increasing the length of time it takes for the eggs to mature. In some cases, these viruses can even sterilize female mosquitoes.

Arboviruses have evolved to expertly use mosquitoes as both transportation vehicles and breeding grounds. By spreading and multiplying without severely harming their insect hosts, these viruses ensure their own survival and continued transmission.

From mosquitoes to humans

The virus must overcome several barriers to successfully colonize a human host.

The initial step for successful disease transmission – the virus’s ultimate goal – is perhaps the easiest: The EEE virus infects humans when a virus-infected female mosquito has an unquenchable appetite for warm blood. From the moment the virus is deposited under the skin through the mosquito’s infected saliva, a tough battle ensues.

The first battle for the virus is to adapt to a typically much hotter setting than the ambient environment – the human body temperature of around 98.6 degrees Fahrenheit (37 degrees Celcius) or higher.

Then, the virus must evade the host’s immediate defenses, which includes physical barriers, such as layers of skin and mucosa, as well as immune cells that detect and attack invading microbes. Once in the bloodstream, the virus faces the adaptive arm of the human immune system, which is capable of targeting specific viral components with exquisite precision, like a biological sniper.

Once the EEE virus reaches the central nervous system – the brain and spinal cord – the immune system can overreact to the infection and inadvertently cause inflammation and damage nerve cells. This can lead to serious long-term effects, such as cognitive impairment.

Person with several mosquito bites on their back, some flies yet clinging to their skin
The human immune response is more robust than that of a mosquito.
Sashunita/Cavan Images via Getty Images

To persist in this hostile human environment, the virus uses various survival strategies. One technique is creating new mutations on its surface and shape-shifting to avoid immune detection. Another strategy is to hijack human cells to replicate itself, such as using the cell’s machinery to synthesize new viral components and altering how the cell regulates division.

As viruses adapt to overcome immune defenses, both humans and mosquitoes evolve countermeasures to fight infection. The greater complexity of the human immune system makes it especially challenging for viruses to survive and spread between human hosts.

From human to human?

Like many other arboviruses, the EEE virus cannot be transmitted from person to person, which effectively limits its spread among human populations. Your body keeps the virus contained. Consequently, when the EEE virus infects people via the bite from an infected mosquito, it is considered a dead end, as it cannot escape its human host or infect another bloodthirsty mosquito.

So, what does the virus that causes EEE gain by infecting people? Not likely anything. A mosquito-borne virus like the Togavirus that causes EEE prefers its established transmission cycle between mosquitoes and birds. Human infections occur only when a mosquito deviates from its typical menu of birds.

EEE spreads more easily between mosquitoes and birds than it does in humans, which helps explain why human infections don’t happen very often. Thankfully, human bodies simply aren’t the virus’s currently preferred environment.The Conversation

Lee Rafuse Haines, Associate Research Professor of Molecular Parasitology and Medical Entomology, University of Notre Dame and Pilar Pérez Romero, Associate Professor of Virology, University of Notre Dame

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

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