Saturday, January 18, 2020

Egg trading by hermaphrodite fish--evolutionary game theory by Peña, Nöldeke, and Puebla

Game theory is about how payoffs among multiple parties change the way they interact with each other. One of the most interesting areas of application is in the study of evolution of populations.  Here's a paper about reciprocity in reproductive strategies that depend on the thickness of various aspects of the market...

The Evolution of Egg Trading in Simultaneous Hermaphrodites
Jorge Peña, Georg Nöldeke, and Oscar Puebla

Abstract: Egg trading—whereby simultaneous hermaphrodites exchange each other’s eggs for fertilization—constitutes one of the few rigorously documented and most widely cited examples of direct reciprocity among unrelated individuals. Yet how egg trading may initially invade a population of nontrading simultaneous hermaphrodites is still unresolved. Here, we address this question with an analytical model that considers mate encounter rates and costs of egg production in a population that may include traders (who provide eggs for fertilization only if their partners also have eggs to reciprocate), providers (who provide eggs regardless of whether their partners have eggs to reciprocate), and withholders (cheaters who mate only in the male role and just use their eggs to elicit egg release from traders). Our results indicate that a combination of intermediate mate encounter rates, sufficiently high costs of egg production, and a sufficiently high probability that traders detect withholders (in which case eggs are not provided) is conducive to the evolution of egg trading. Under these conditions, traders can invade—and resist invasion from—providers and withholders alike. The prediction that egg trading evolves only under these specific conditions is consistent with the rare occurrence of this mating system among simultaneous hermaphrodites.

Here's the full text.

Friday, January 17, 2020

Germany sticks with opt-in donation for deceased donor organs for transplants

Axel Ockenfels points me to this story, in English, in Deutsche Welle:

German parliament: Explicit consent still necessary from organ donors
Germany's parliament has rejected a health ministry proposal for a new organ donation system. With low donor numbers, the health minister wanted a presumed-consent system, with the onus on people to refuse to donate.
Date 16.01.2020  Author Mark Hallam, Astrid Prange

"Germany's organ donation rules will remain largely unchanged after an emotional debate in the Bundestag on Thursday morning. The country will stick with a system of informed consent, whereby only people who voluntarily register as organ donors are eligible. Most, but not all, EU members have moved to an opt-out system that presumes a willingness to donate.
Presumed vs. informed consent
"Health Minister Jens Spahn, a Christian Democrat, had led the push to reform the system along with a Social Democrat, Karl Lauterbach. They had proposed a system of presumed consent, albeit also adding the chance for relatives to object to organ donations after the person's death. The motion failed by 292 votes to 397.
"A rival proposal, put forward by a group led by Green party lawmaker Annalene Baerbock, passed by 432 votes to 200, with 37 abstentions, in the decisive final vote. It advocated keeping the existing system of informed consent. However, in a bid to shorten Germany's transplant waiting lists, people will be asked when renewing their national identity cards if they'd like to donate organs. "

****************
Recent, somewhat related post:

Monday, November 11, 2019

Thursday, January 16, 2020

Vacancy chains and hermit crab housing, revisited

Here's the story from the NY Times (with a nice video):
Even Hermit Crabs Have Wealth Inequality  by Elizabeth Preston, Dec. 13, 2019


"Hermit crabs face a uniquely competitive real estate market. They need bigger and bigger shells throughout their lives, but can’t grow these homes themselves. So they rely on castoff snail shells, and are constantly on the lookout for better properties entering the market.
A study that will be published next month in the journal Physica A found that the distribution of these shells in one hermit crab population was surprisingly similar to the distribution of wealth in human societies."

And here's the paper in Physica A.

A comparison of wealth inequality in humans and non-humans
 Ivan D.Chase, Raphael Douady, Dianna K.Padilla

"Abstract: Inequality in the distribution of material resources (wealth) occurs widely across human groups. The extent of inequality, as measured by the Gini coefficient, is less in small-scale societies, such as hunter-gatherers and pastoralists, and greater in large-scale ones like current nation states. In many societies, the statistical distribution of wealth takes a characteristic form: unimodal, skewed to the right, and fat-tailed. However, we have relatively little systematic information about the distribution of material resources in nonhuman animals even though such resources are vital to their survival and fitness. Here we present the first description of inequality in material resources in an animal population: the distribution of gastropod (snail) shells inhabited by the hermit crab Pagurus longicarpus. We find that the shell distribution for the crabs strongly resembles the characteristic form of wealth distribution in human groups. The amount of inequality in the crabs is more than that in some small-scale human groups but less than that in nations. We argue that the shell distribution in the crabs is not simply generated by biological factors such as survival and growth of either crabs or gastropods. Instead, the strong resemblance in the human and hermit crab distributions suggests that comparable factors, not dependent upon culture or social institutions, could shape the patterns of inequality in both groups. In addition to the similarity in their inequality distributions, human and hermit crabs share other features of resource distribution, including the use of vacancy chains, not seen in other species. Based upon these parallels, we propose that P. longicarpus could be used as an animal model to test two factors – individual differences and intergenerational property transfers – that some economists theorize as major factors influencing the form of wealth distributions in humans. We also propose that inequality in hermit crabs could provide a baseline for examining human inequality.
***********
(297 crabs were re-homed to produce this paper about economics, published by biologists in a physics journal.)

See earlier post:

Saturday, July 21, 2012 Hermit Crab Vacancy Chains


Wednesday, January 15, 2020

Kidney Exchange in Israel (supported by Itai Ashlagi)

Dr. Tamar Ashkenazi, the head of the Israel National Transplant Center, writes in Maariv:

בשורה חשובה לחולים בארץ: הקמת המאגר הארצי להשתלות מוצלבות
רופאים משתילי כליות ונפרולוגים הגדירו את הכללים למציאת התאמות כמו נוגדנים, זמן המתנה להשתלה ועוד. כללים אלו הוגדרו בתוכנת ההצלבות של המרכז להשתלות
ד"ר תמר אשכנזי
Google translate: Important news for patients in Israel: The establishment of the national crossover transplant reservoir
Kidney transplant doctors and nephrologists have defined the rules for finding matches like antibodies, waiting time for transplant and more. These rules were defined in the Transplant Center's cross-over software.  by Dr. Tamar Ashkena

"The National Kidney-Exchange Transplant Database was established this year as part of the National Transplant Center's activities. One of the developers of the exchange program, Prof. Itai Ashlagi an Israeli who teaches at Stanford University in the USA, regularly assists the program. Kidney transplant and nephrologists have defined the rules for finding matches such as antibodies, waiting time for transplantation and more. Since April 2019, a number of exchanges have been found, and the record of course was a chain of six transplants jointly with the Czech Republic last month. Collaboration with other countries increases the possibility of finding accommodations, and this is important news for patients in the country. We call on all patients whose family members have not been found suitable to donate a kidney, which will join the national and international pool." 

**********

Itai mentions that Sukolsak Sakshuwong, a PhD student at Stanford from Thailand, has been instrumental in developing the software.

Tuesday, January 14, 2020

Matching for platonic co-parenting: "like a divorce, without the wedding or the arguments."

The WSJ has the story, about two web sites that are trying to pioneer matching for people who want to conceive a child who will have two involved parents, who won't be married to each other:

Co-Parenting Sites Skip Love and Marriage, Go Right to the Baby Carriage
A new kind of online service matches people who want to have children, but not necessarily romance 
By Julie Jargon

"When Jenica Andersen felt the tug for a second child at age 37, the single mom weighed her options: wait until she meets Mr. Right or choose a sperm donor and go it alone.

"The first option didn’t look promising. The idea of a sperm donor wasn’t appealing, either, because she wanted her child to have an active father, just like her 4-year-old son has. After doing some research, Ms. Andersen discovered another option: subscription-based websites such as PollenTree.com and Modamily that match would-be parents who want to share custody of a child without any romantic expectations. It’s a lot like a divorce, without the wedding or the arguments."
...
"Given the prominence in today’s society of both single parenthood and online dating, this digital approach could be seen as a natural progression. It could also be considered shocking or even, as some have called it, an affront to marriage.
***********

Here's Pollentree.com: https://www.pollentree.com/, which also offers to match prospective moms with sperm donors.

And here's Modafamily: https://modamily.com/, which speaks of romantic, co-parenting, or known-donor relationships.

Monday, January 13, 2020

The organization of organ donation: Jennifer Erikson and Abe Sutton call for an Office of Organ Policy

White House staffers from two very different administrations call for a reorganization of organ donation:

It's time to provide needed reform to the organ donation system
BY JENNIFER ERICKSON AND ABE SUTTON

"Every day, Americans are dying because of an inefficient organ donation system. That reality is as tragic as it is fixable, and cemented a seemingly unlikely friendship between us as two former White House staffers who served two very different presidents.

"It might seem like there are not many points of policy agreement between the Trump and Obama White House, but organ donation reform is one.
...
"Organ donation policy has been split between different agencies within the federal government and even an external federal contractor called the Organ Procurement Transplantation Network. This splintering of responsibilities has led to an unaccountable system with patients left behind. As for one federal contractor responsible for oversight of other contractors, Grassley and Young called out the problem, writing: “we can no longer stand by idly while the fox guards the hen house.”

"The answer is to create a centralized Office of Organ Policy within HHS able to identify opportunities for reform, manage the system, and ensure that lives are saved and taxpayer dollars meant to support the system are not wasted."



HT: Frank McCormick 

Sunday, January 12, 2020

Regulation of transplant centers and OPO's

I'll be speaking this morning on regulation of transplantation at the 2020 Winter meetings of the American Society of Transplant Surgeons in Miami.

I'll be in a  Special Invited Presidential Session: Transplantation Metrics Roundtable     Moderators:Lloyd Ratner, MD, MPH Timothy Pruett, MD



Transplantation Metrics Roundtable
Time
End Time
Presentation
Speaker
Moderators
10:05 AM
10:20 AM
Welcome and Introduction
Lloyd Ratner, MD, MPH
Lloyd Ratner, MD, MPH
Tim Pruett, MD
10:20 AM
10:35 AM
Introductory Presentation from Dr. Pruett
Tim Pruett, MD
10:35 AM
10:50 AM
Introductory Presentation from Dr. Roth
Al Roth, PhD
10:50 AM
12:00 PM
Transplantation Metrics Roundtable Discussion
All panelists (listed below)

Panel Participants
Paul Conway – Chair of Policy and Global Affairs and Immediate Past President of AAKP
Alexandra Glazier – CEO of New England Donor Services
Rick Hasz, BS, MFS, CPTC – Vice President of Clinical Services for the Gift of Life Donor Program
Maryl Johnson, MD – President of UNOS and Professor of Medicine, Heart Failure & Heart Transplantation at University of Wisconsin
Richard Knight, MBA – President of AAKP
Kevin Longino – CEO of the National Kidney Foundation (NKF)
Jean Moody-Williams, RN, MPP – Deputy Director of the Center for Clinical Standards and Quality at Centers for Medicare and Medicaid Services (CMS)
Ken Moritsugu, MD, MPH, FACPM – Rear Admiral, U.S. Public Health Service (Retired) and Acting Surgeon General of the United States in 2002 and from 2006–2007
Alvin Roth – Professor of Economics at Stanford University and awarded the 2012 Nobel Memorial Prize in Economics


The title of my talk (which Alex Chan and I prepared) is:
Performance Metrics and Regulation of Transplantation

Saturday, January 11, 2020

Kidney exchange, in French, in Forbes

Here's a short interview in French about kidney exchange, in Forbes France:

Alvin Roth, Lauréat Du Prix Nobel D’Economie Veut Revolutionner Les Dons De Reins
Philippe Branche   10 janvier 2020

Here's one bit:

Are you currently working with politicians, legislators or medical administrators to resolve this problem ?
Alvin Roth: I am, but not with great success. I recently spoke to decision makers in several countries: India, China, Germany, Canada and of course the United States. In October, renowned bioethicist Peter Singer expressed strong support for the Global Kidney Exchange Program, so that recently the idea of ​​expanding kidney exchange to include international exchanges has gained momentum. I also recently debated with a member of the Bundestag, the German parliament. In Germany, kidney transplantation from a living donor is legal, but a patient can only receive a kidney from an immediate family member, and therefore the literal interpretation of the law makes it impossible to exchange kidneys. German law provides that monetary exchanges of parts of the human body are illegal and, apparently, it is to avoid any possibility of payment for a kidney that the limitation to family members is applied. A minimal amendment to German law could allow immediate family members to make an indirect donation, via the kidney exchange system, which would preserve the confidence that the donor was not paid to make an exchange. By designing this market in this way, we are trying to expand the database and reduce the waiting time for sick people.

Friday, January 10, 2020

Risk attitudes in transplantation--then and now

Organ transplantation has become much more organized since its early days, for both good and ill.

Today there's a good deal of regulation of transplant centers, which need very high success rates (one year graft survival rates in particular) to remain in the good graces of government and private payers.

It wasn't always so.

Here's a quote from Lloyd Ratner's Message from the ASTS President for November 2019:

"In the transplant world, this [perseverance] is best exemplified by Thomas Starzl’s ceaseless quest to make liver transplantation a reality. Between March 1963 and May 1967, Dr. Starzl performed his first 7 liver transplants at the University of Colorado, all of whom died in the peri-operative period. The longest survivor succumbed after 23 days to “sepsis, bile peritonitis, and liver failure.” Despite this disastrous start, Dr. Starzl persevered. Starzl’s eighth patient, transplanted for hepatocellular carcinoma, lived 400 days before dying from carcinomatosis. By 1990 the programs that Dr. Starzl directed in Pittsburgh would perform 571 liver transplants in a single year and would train many of the world’s leaders in the field."

Thursday, January 9, 2020

Reforming stock exchange governance, from the SEC

It's good to know that sometimes the SEC reads papers by market designers (in this case Budish et al.):

Statement on Reforming Stock Exchange Governance by Commissioner Robert J. Jackson Jr., Jan. 8

"As today’s release explains, America’s stock markets are riven by a fundamental conflict of interest: exchanges both operate public data feeds and profit from selling superior private ones.[1] Because exchanges have no economic reason to produce robust public data on stock prices, investors have long demanded a vote on how the public feeds are run.[2] Rather than give investors a real say over the data that drives our markets, today’s release merely invites for-profit exchanges to draft their own rules on these questions. Because that approach has failed investors before, and there’s no reason to expect it to succeed now, I respectfully dissent.
*          *          *          *
In 1934, American investors struck a fundamental bargain with our stock exchanges. The Commission was created to oversee the markets, and nonprofit exchanges were given the special legal status they needed to play a role in protecting ordinary investors.[3] But over a decade ago the deal changed: Exchanges became for-profit entities with powerful incentives to maximize profits, not protect investors.
That’s how we ended up with the two-tiered system for market data we have today. Congress mandated the creation of a public feed when exchanges were still nonprofits, but today’s for-profit exchanges also sell their own private feeds. So it’s unsurprising that exchanges underinvest in the public feed—it’s a product they directly compete with. The only question is what the Commission should do about it. Rather than recognize the reality of the exchanges’ incentives, the Commission today chooses hope over experience, asking exchanges to act contrary to their own economic interests.[4] For two reasons, we should not expect that approach to produce the robust public data that American investors deserve.
First, by proposing an order under a national market system (NMS) plan, we’re asking the exchanges to tell us how best to address the conflicts of interests that currently allow them to profit by controlling the public feed while selling superior private data.[5] No one should be surprised when the exchanges respond that, rather than give investors votes on the operation of the public feed, they’d rather continue controlling it themselves.[6] Instead of a clear solution to an obvious problem, today’s proposal will produce little more than a long process that will benefit lobbyists and lawyers—but not the ordinary investors living with the tax of rising data costs in our markets.[7]
Second, our history governing markets through NMS plans is hardly encouraging. One need look no further than the consolidated audit trail to see what happens when the Commission replaces real regulation with mere hope that stock exchanges will act against their own interests. The CAT was launched in the wake of a terrifying market event nearly a decade ago. Both Chairman Clayton and Director Redfearn have done tremendous work to move it forward. But our predecessors left the construction of the CAT to the NMS process. And the CAT will protect investors, not produce profits. So it’s no surprise that the CAT is still not complete.[8] I hope our successors won’t someday say the same about today’s attempt to reform exchange governance.
*          *          *          *
Those who, like me, are frustrated by today’s failure to require real reform may be tempted to direct their ire towards our stock exchanges. But it’s a mistake to blame private enterprises for maximizing the profit opportunities the law gives them.[9] Instead, we should change the law to address the incentives produced by giving exchanges both control over our public feeds and the opportunity to profit by selling private ones.[10] Without changing those incentives, we cannot and should not expect the market to fix the market.[11]
That’s why I hope commenters will come forward and urge the Commission to do more than merely hope that stock exchanges will act contrary to their private interests. Until we do, our stock markets will continue to fall short of the level playing field that ordinary American investors deserve."
....
"[11] Important recent research shows that, even when the market for trading is perfectly competitive, exchanges can extract supra-competitive rents from selling speed technology in the form of proprietary data feeds. See Eric Budish, Robin S. Lee & John J. Shim, Will the Market Fix the Market? A Theory of Stock Exchange Competition and Innovation, National Bureau of Economic Research Paper No. w25855 (2019)."

Wednesday, January 8, 2020

Deceased donor organs and nautical miles

UNOS has recently announced a new distribution system for deceased kidney and pancreas offers: instead of being offered first to waiting-list patients at transplant centers in the same one of the 58 Donor Service Areas and then one of the 11 OPTN geographical regions as the donor hospital, they will now be offered first to patients on the waiting lists of transplant centers within 250 nautical miles of the donor hospital.

(Why nautical miles? I don't know, but you can read the various proposals that were considered before deciding on 250 of them at this earlier post: Sunday, May 12, 2019  UNOS proposal for public comment: Eliminate the use of DSAs and regions from kidney and pancreas distribution.)

Here is the new (Dec 5, 2019) announcement: 

"Under the newly approved system, expected to be implemented in 2020, kidney and pancreas offers (except for rare, very well-matched donor and recipient combinations nationwide) will be offered first to candidates listed at transplant hospitals within 250 nautical miles of the donor hospital. Offers not accepted for any of these candidates will then be made for candidates beyond the 250 nautical mile distance.

"Candidates also will receive proximity points based on the distance between their transplant program and the donor hospital. Proximity points are intended to improve the efficiency of organ placement by adding priority for candidates closer to the donor hospital. Candidates within the initial 250 nautical mile radius will receive a maximum of two proximity points, while those outside the initial circle will receive a maximum of four proximity points. The point assignment will be highest for those closest to the donor hospital and will decrease as the distance increases.

"Differences from current system and predicted benefits

"The new system will replace a three-tiered approach used since the beginning of national organ allocation policies in the mid-1980s. Currently, most kidney and pancreas offers go first to candidates listed at hospitals within the same donation service area (DSA) where the donor hospital is located. There are 58 DSAs reflecting the assigned service area of organ procurement organizations (OPOs). These DSAs are fixed, often irregular geographic boundaries, and were not set for the express purpose of optimizing organ allocation. In some instances, portions of the same DSA are not contiguous, meaning that some “local” donor matches may travel through service areas belonging to other OPOs.

"Organ offers not accepted at the DSA level currently are made to candidates at hospitals within the same OPTN region as the donor hospital. Finally, offers not accepted at the DSA or regional level are made to candidates listed at transplant programs anywhere else in the United States.
************
One impetus for the move away from geographic allocation within strict borders is because that system was challenged in the courts, see

Under the new system, arbitrary borders will no longer have such a big effect on access to transplantation. (Except that is for international borders, which are often still insuperable barriers...)

Tuesday, January 7, 2020

Fake rhino horn

When is it ok to fight one repugnant transaction with another?  The New York Times has a story of fighting the (repugnant) sales of rhinoceros  horn by flooding the market with fake rhinoceros horn, i.e. fighting the species-endangering trafficking of rhino horn by selling fakes.  Of course the success of such a strategy for reducing poaching depends on whether fakes are a substitute or a complement for the real thing--e.g. it will fail if the fakes increase the size of the market in ways that increases poaching, rather than satisfying the demand more cheaply (or if fear of convincing fakes reduces demand...)

Scientists Created Fake Rhino Horn. But Should We Use It?
Experts are divided over whether flooding the Asian market with convincing artificial rhino horn would help or hurt rhinos’ survival.  By Rachel Nuwer

"In Africa, 892 rhinos were poached for their horns in 2018, down from a high of 1,349 killed in 2015. The decline in deaths is encouraging, but conservationists agree that poaching still poses a dire threat to Africa’s rhino population, which hovers around 24,500 animals.
Now, in the hopes of driving down the value of rhino horn and reducing poaching even more, scientists have created a convincing artificial rhino horn made from horsehair.
... 
Dr. Vollrath believes his artificial horn could be used to covertly flood the market with a cheap, convincing replacement, reducing the demand that leads to rhinos being slaughtered. He also hopes it might provide an educational tool for “demystifying that rhino horn’s something very special,” he said.
...
"Critics say that fake rhino horn risks stimulating demand for real horn, and that it would complicate policing. “There’s already scarce resources for wildlife crime and we don’t want to make it even more difficult for law enforcement,” said Ms. Swaak-Goldman, who works with governments and law enforcement agencies.
Peter Knights, chief executive officer of WildAid, a nonprofit organization dedicated to ending illegal wildlife trade, added that the market in Vietnam is already flooded with convincing fakes, like water buffalo horn, which accounts for up to 90 percent of what’s sold as rhino horn. “It’s widely known that there is a lot of fake product out there, so this experiment is already running,” Mr. Knights said."
*************
See also

The Economics of Synthetic Rhino Horns

32 Pages Posted: 24 Aug 2016 Last revised: 10 Aug 2017

Frederick Chen

Wake Forest University
Date Written: June 1, 2017

Abstract

To examine the potential impact of synthetic horns to reduce rhino poaching, a formal model of the rhino horn market in which there exist firms with the capability to produce high quality synthetic horns is presented and studied. The analysis shows that whether the availability of synthetic horns would decrease the equilibrium supply of wild horns -- and how much the reduction would be -- depends on market structure -- i.e., how competitive the synthetic horn production sector is -- and on how substitutable the synthetic horns are for wild horns. The implications of these results for conservation policies are derived and discussed. Synthetic horn producers would benefit more by promoting their products as being superior to wild horns, but this could increase horn prices and lead to more rhino poaching. For conservation purposes, it may be beneficial to incentivize firms to produce inferior fakes -- synthetic horns that are engineered to be undesirable in some respect but difficult for buyers to distinguish from wild horns. The analysis also shows that promoting competition in the production of synthetic horns in general is desirable from a conservation standpoint as synthetic horn producers may prefer to keep prices at a high enough level that could still encourage significant amount of poaching.

Monday, January 6, 2020

Social studies of markets, marketplaces, and market design in the journal Economy and Society

Economists aren't the only social scientists who study markets and market-like institutions and organizations, and some of the study of markets by non-economists falls under the loose heading of 'Social studies of markets'.

The Journal Economy and Society  has a special issue on Markets for Collective Concerns and their Failures (Volume 48, 2019 - Issue 2).

The articles in the issue focus both on the social study of markets per se, and on critiquing the way such studies are conducted.

The introductory article, "The organization of markets for collective concerns and their failures," by Christian Frankel, José Ossandón & Trine Pallesen, all professors in the Department of Organization at Copenhagen Business School. summarizes the object of study by noting that
"Sociologists of different traditions share the view that part of their task is to provide definitions of markets." (emphasis added).

The concluding article, "On going the market one better: economic market design and the contradictions of building markets for public purposes,"  by Edward Nik-Khah and Philip Mirowski, criticizes social scientists for not taking sufficient account of market design, and criticizes market design for transforming markets from general purpose natural institutions into specialized human artifacts.

I find the level of abstraction in some of this work hard to follow. I guess I take it for granted that different markets are different, and that markets and marketplaces are (and always have been) human artifacts. (I agree though that sometimes other, more abstract simple views have held sway even among economists, and so I also agree that market design can take a bow for at least helping to add some nuance to the view that markets are simply emergent phenomena that arise without human intervention...)

But academic ideas influence popular ideas, and abstract ideas about markets have consequences. To paraphrase Keynes, I think it is sometimes the case that 'Practical men who believe themselves to be quite exempt from any intellectual influence,' are sometimes influenced by ideas about "markets" in the abstract.  So I'll probably continue to try to follow this kind of work, although I'm often disappointed that it doesn't help me to better understand markets and marketplaces and their roles in society.

Here's the table of contents of the special issue.

Article
Pages: 153-174
Published online: 16 Jul 2019
OpenURL Stanford University
  • 564Views
  • 0CrossRef citations
  • 4Altmetric
Article
Pages: 175-196
Published online: 16 Jul 2019
OpenURL Stanford University
  • 346Views
  • 0CrossRef citations
  • 2Altmetric
Article
Pages: 221-242
Published online: 19 Jul 2019
OpenURL Stanford University
  • 243Views
  • 0CrossRef citations
  • 2Altmetric