Fall M.M.,African Institute for Mathematical Sciences |
Valdinoci E.,Weierstrass Institute for Applied Analysis And Stochastics
Communications in Mathematical Physics | Year: 2014
We consider the equation (-Δ)su + u, with s ∈ (0, 1) in the subcritical range of p. We prove that if s is sufficiently close to 1 the equation possesses a unique minimizer, which is nondegenerate. © 2014 Springer-Verlag Berlin Heidelberg.
News Article | February 16, 2017
BOSTON, MA (February 16, 2017) --Organizers of the 10th World Conference of Science Journalists (WCSJ2017) unveiled details of the upcoming event at an information session held today at the annual meeting of the American Association for the Advancement of Science. Announcements included program themes, new plenary speakers, an initiative to serve attendees from Latin America and the Caribbean, pre- and post-conference activities, an update on conference fundraising, and travel fellowships. WCSJ2017, which will take place October 26-30, 2017 in San Francisco, California, marks the first time that this international gathering of science journalists from the Americas, Africa, Asia, Australia, and Europe will be held in the United States. The conference will continue its tradition of welcoming colleagues from across the globe. Organized by the National Association of Science Writers (NASW) and the Council for the Advancement of Science Writing (CASW) in partnership with the World Federation of Science Journalists (WFSJ), it is expected to attract 1,200 attendees from over 80 countries and will be based at the San Francisco Marriott Marquis. The University of California San Francisco and UC Berkeley will together host a day of sessions and activities, followed by a day of science-themed field trips. --The selection of 47 breakout sessions by the WCSJ2017 Program Committee, a science committee, and the Association of Health Care Journalists (AHCJ), which will produce a global health journalism track. The sessions were chosen from more than 400 submitted proposals. Program themes will include: --The addition of five plenary speakers to the program: The program will also include a plenary session on Pseudoscientific Policies and Authoritarian Governments. Previously announced podium speakers include Thierry Zomahoun, president and chief executive officer of the African Institute for Mathematical Sciences, and UC Berkeley biologist Jennifer Doudna. The organizers announced that The Hastings Center, a bioethics research institute in New York, will organize a pre-conference symposium, "New Genetic Technologies: Ethical Debates and Global Science Policy." The Hastings Center symposium is part of an international scholarly project exploring "Gene Editing and Human Flourishing," with funding from the Templeton Foundation. Other planned pre-conference activities are training for student journalists and a full-day workshop for Latin American and Caribbean journalists. The Hastings Center and AHCJ are among several sponsors and partners who have recently joined to support WCSJ2017. Others include the Alfred P. Sloan Foundation, Bayer, The Brinson Foundation, and Nature. Johnson & Johnson Innovation is the conference's Diamond Sponsor and lead underwriter. Post-conference field trips are being organized by the Northern California Science Writers Association. NCSWA President Bob Sanders reported that the committee has "neat trips set up to the Monterey Bay Aquarium and to the Monterey Bay Aquarium Research Institute (MBARI), the UC Davis enology field station in Napa Valley's wine region, a seismology walk along the Hayward Fault, a USGS trip to coastal slide hazard areas, a visit to X, Google's moonshot factory, and an interactive immersion in drug development at Bayer." In a fundraising progress report, the organizers announced that more than $1.1 million in commitments have been secured toward the $2 million in sponsor and partner funding needed to support travel, program delivery, networking, and infrastructure for the conference. CASW and WFSJ are jointly recruiting conference sponsors. Varied sponsorship opportunities are available for foundations, science and media organizations, businesses, and individuals. A special fund for individual donations to support international travel fellowships to WCSJ2017 has been set up by CASW in honor of David Perlman, the longtime science editor for the San Francisco Chronicle and a past president of CASW and NASW. An anonymous donor is matching all donations until the fund reaches its goal of $20,000 in individual contributions. Organizers said they are within $4,000 of meeting the goal and continue to welcome donations online at wcsj2017.org. More than 75 online applications for travel fellowships have been received since the application window opened four weeks ago, including 17 applications for student fellowships. Fellowships will be awarded to attendees from the U.S. and around the world, with an emphasis on enabling attendance by those in developing countries, Latin America, and the Caribbean. The deadline for submission is March 15. Conference registration will open in early May. The organizers emphasized that the conference partners will do everything possible to bring colleagues from all nations to the conference. In a February 8 statement about travel to the U.S., they said: "We are resolute in our determination that the conference will continue its tradition of welcoming colleagues from across the globe, and we oppose any restrictions that would prevent participants from attending WCSJ2017. As October approaches, we will do everything we can to make the meeting accessible to all." CASW: Founded in 1959, the Council for the Advancement of Science Writing is a panel of distinguished journalists, science communication specialists, and scientists committed to improving the quality and quantity of science news reaching the public. CASW has joined with WFSJ to raise funds to support travel to WCSJ2017 for developing-country journalists, as well as hospitality and conference program expenses. NASW: Founded in 1934, the National Association of Science Writers is an association of more than 2,000 members chartered to "foster the dissemination of accurate information through all media normally devoted to informing the public." NASW's programs improve the craft of science writing, fight for the free flow of science news, and honor excellence in science writing. WFSJ: The Montréal-based World Federation of Science Journalists connects science journalists in more than 50 associations around the world through conferences, competitions, and networking, and encourages strong, critical coverage of issues in science and technology, environment, health and medicine, agriculture, and related fields. Current programs help journalists worldwide learn about infectious diseases, including Ebola and hepatitis C. WFSJ offers an online science journalism course in 10 languages. UCSF and UC Berkeley: UC San Francisco is the leading university in the U.S. exclusively focused on health. UCSF is dedicated to advanced biomedical research, graduate-level education in the life sciences and health professions, and excellence in patient care. UC Berkeley is the flagship of the University of California system. Its undergraduate program ranks third overall among the world's universities in the latest U.S. News & World Report rankings, while its graduate research programs uniformly rank among the best in the world. Combined, current UCSF and UC Berkeley faculty have earned more than 25 Nobel Prizes. Rosalind Reid, executive director, Council for the Advancement of Science Writing: firstname.lastname@example.org
News Article | November 15, 2016
KIGALI, Rwanda, 15 novembre 2016 /PRNewswire/ -- Le Next Einstein Forum (NEF) - le forum mondial pour la science en Afrique - lance aujourd'hui sont deuxième appel à candidatures pour le programme des lauréats du NEF. La nouvelle promotion rejoindra 15 des meilleurs jeunes scientifiques africains, la première promotion de lauréats du NEF et présentera leur recherches et innovations lors de la Rencontre internationale 2018 du NEF, qui se tiendra en mars 2018 à Kigali, au Rwanda. Le NEF, une initiative de l'African Institute for Mathematical Sciences (AIMS) en partenariat avec la Fondation Robert Bosch, est une plateforme mondiale qui connecte la science, la société et les politiques en Afrique et dans le reste du monde, avec la science comme levier du développement humain à l'échelle mondiale. En mars de cette année, le NEF, en partenariat avec le gouvernement du Sénégal, a organisé la Rencontre internationale 2016 du NEF, le premier forum mondial pour la science sur le sol africain, réunissant plus de 1 000 participants du domaine de la recherche, des universités, du gouvernement, du secteur privé et de la société civile. La Rencontre internationale a mis l'accent sur la façon dont la science et la technologie peuvent résoudre les défis mondiaux. « Après une fructueuse première Rencontre internationale, nous sommes ravis de lancer le processus de recrutement de la prochaine promotion des plus brillants jeunes scientifiques d'Afrique. La première promotion, grâce à ses présentations captivantes lors de la Rencontre internationale du NEF à Dakar, a prouvé au monde que l'Afrique est une source de recherche de pointe, d'innovations pouvant changer des vies et de leadership scientifique. Les lauréats du NEF sont en train de briser des barrières et d'inviter des collaborations internationaux, ce qui est nécessaire pour la voie du développement de l'Afrique et du monde. Nous sommes tellement confiants que cette année, nous avons augmenté le nombre de lauréats du NEF, passant de quinze à vingt places», a déclaré M. Thierry Zomahoun, Président du NEF et PDG d'AIMS. L'appel à candidatures au Programme des Lauréats du NEF est ouvert aux Africains du monde entier - y compris à ceux de la diaspora – qui se distinguent dans une quelconque des disciplines scientifiques, dans les domaines des sciences sociales, des humanités et de la technologie. Les candidats doivent avoir moins de 42 ans, être titulaires d'un Doctorat et avoir fait une recherche/découverte de référence qui a eu un impact à l'échelle mondiale. Dr. Ingrid Wuenning Tschol, Première Vice-Présidente en charge de la Stratégie de la Fondation Robert Bosch, qui a noué un partenariat avec l'AIMS afin de créer le NEF, a affirmé : « Comme nous l'avons vu au Sénégal, les lauréats du NEF sont des leaders dans leurs domaines. Ils effectuent de brillantes recherches et encadrent la prochaine génération de scientifiques africains. Ils démontrent le potentiel de l'Afrique au monde entier mais aussi aux leaders africains. Alors que nous lançons le nouvel appel à candidatures, nous espérons susciter davantage de collaborations parmi les scientifiques du continent et à l'échelle mondiale. Nous estimons également que l'intensification des recherches sur le continent africain aura un impact positif durable pour le monde. Nous encourageons tous ceux qui sont éligibles à soumettre leur candidature au programme». En plus de participer à la Rencontre internationale 2018 du NEF et d'y présenter leurs travaux, les lauréats du NEF participeront à des voyages de recherche et à des semaines de visite en tant que chercheurs invités auprès de partenaires. En outre, leurs interventions, ainsi que leurs publications à l'échelle mondiale seront également facilitées et ils seront soutenus dans leurs recherches. Le mandat des lauréats du NEF s'étend jusqu'au 30 juin 2019. Le processus ouvre le 15 novembre 2016 jusqu'au 27 janvier 2017 et les formulaires de candidatures sont disponibles sur nef.org/fellows. La liste des lauréats du NEF sélectionnés sera communiquée en juin 2017. Découvrez nos lauréats du NEF 2016/2017 ici. Lancé en 2013, le Next Einstein Forum (NEF), une initiative de l'African Institute for Mathematical Sciences (AIMS) en partenariat avec la Fondation Robert Bosch, organise les Rencontres internationales biennales du NEF, durant lesquelles des centaines d'intellectuels de renom et d'intervenants distingués du monde entier se retrouvent en Afrique pour placer la science au centre du développement mondial. La prochaine Rencontre internationale 2018 du NEF sera organisée à Kigali, au Rwanda en mars 2018 sous le haut patronage de S.E.M. Paul Kagame, Président de la République du Rwanda. Le NEF est reconnu par la Commission de l'Union africaine, l'Organisation des Nations Unies pour l'éducation, la science et la culture (UNESCO), les gouvernements du Rwanda, du Sénégal et de l'Afrique du Sud, l'Académie africaine des sciences (AAS) et par un nombre croissant de partenaires du secteur privé à travers le monde qui ont à cœur de donner à la communauté scientifique africaine une place au sein de la communauté scientifique mondiale, ce qui assurera le développement humain durable en Afrique et dans le reste du monde. En sus de la Rencontre internationale du NEF, le Next Einstein Forum mène le Programme de Lauréats du NEF et le Programme des Ambassadeurs du NEF (qui rassemble 54 jeunes férus de science, technologie, ingénierie, mathématiques et sciences sociales, passionnés à l'idée de démontrer l'impact de la science dans la vie de tous les jours dans leurs pays respectifs). Le NEF abrite également des initiatives politiques, notamment les Réunions ministérielles sur la Science et l'Enseignement et publie une Déclaration lors de chaque Rencontre internationale, contenant des mesures concrètes visant à accroître le rendement de l'Afrique en matière de science et d'innovation. En outre, en 2017, le NEF commencera à organiser des tables rondes science-secteur privé-politique en vue d'encourager la collaboration des parties prenantes. Le but est de mobiliser 100 millions de $US d'ici 2020 en faveur de la recherche et de l'engagement public en Afrique et de faire participer 100 millions de jeunes à la science et à la technologie sur le continent. Nous sommes convaincus que le prochain Einstein sera Africain. Pour plus d'informations, rendez-vous sur nef.org Twitter: @NextEinsteinFor Facebook: NextEinsteinForum
Bellini E.,University of Heidelberg |
Sawicki I.,African Institute for Mathematical Sciences
Journal of Cosmology and Astroparticle Physics | Year: 2014
We present a turnkey solution, ready for implementation in numerical codes, for the study of linear structure formation in general scalar-tensor models involving a single universally coupled scalar field. We show that the totality of cosmological information on the gravitational sector can be compressed - without any redundancy - into five independent and arbitrary functions of time only and one constant. These describe physical properties of the universe: the observable background expansion history, fractional matter density today, and four functions of time describing the properties of the dark energy. We show that two of those dark-energy property functions control the existence of anisotropic stress, the other two - dark-energy clustering, both of which are can be scale-dependent. All these properties can in principle be measured, but no information on the underlying theory of acceleration beyond this can be obtained. We present a translation between popular models of late-time acceleration (e.g. perfect fluids, f(R), kinetic gravity braiding, galileons), as well as the effective field theory framework, and our formulation. In this way, implementing this formulation numerically would give a single tool which could consistently test the majority of models of late-time acceleration heretofore proposed. © 2014 IOP Publishing Ltd and Sissa Medialab srl .
Vakili B.,Chalous Branch |
Khosravi N.,African Institute for Mathematical Sciences
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012
In an open Friedmann-Robertson-Walker (FRW) space background, we study the classical and quantum cosmological models in the framework of the recently proposed nonlinear massive gravity theory. Although the constraints which are present in this theory prevent it from admitting the flat and closed FRW models as its cosmological solutions, for the open FRW universe it is not the case. We have shown that, either in the absence of matter or in the presence of a perfect fluid, the classical field equations of such a theory adopt physical solutions for the open FRW model, in which the mass term shows itself as a cosmological constant. These classical solutions consist of two distinguishable branches: One is a contacting universe which tends to a future singularity with zero size, while another is an expanding universe having a past singularity from which it begins its evolution. A classically forbidden region separates these two branches from each other. We then employ the familiar canonical quantization procedure in the given cosmological setting to find the cosmological wave functions. We use the resulting wave function to investigate the possibility of the avoidance of classical singularities due to quantum effects. It is shown that the quantum expectation values of the scale factor, although they have either contracting or expanding phases like their classical counterparts, are not disconnected from each other. Indeed, the classically forbidden region may be replaced by a bouncing period in which the scale factor bounces from the contraction to its expansion eras. Using the Bohmian approach of quantum mechanics, we also compute the Bohmian trajectory and the quantum potential related to the system, which their analysis shows are the direct effects of the mass term on the dynamics of the universe. © 2012 American Physical Society.
News Article | March 16, 2016
How can architects and town planners help clinicians to tackle tuberculosis? What is space-time? These are among the questions being explored by African scientists who last week joined together to open the world’s first truly pan-African scientific gathering. The Next Einstein Forum (NEF), held in Dakar, Senegal, deserves to become a regular feature of the global science landscape. Its purpose: to publicly celebrate and support some of the most outstanding young researchers active in, or closely tied to, the continent. There were 15 NEF Fellows in Dakar last week — from Egypt, Morocco, South Africa, Senegal, Ethiopia and places in between (see http://nef.org/nef-fellows). All have proved themselves as scientists, and all have deep connections with Africa. Most work on the continent; others are based in prestigious institutions in the United States and in Europe, forming part of the sort of diaspora on which other regions — especially China — have built a thriving research ecosystem. The launch included a scintillating show by African singers and dancers, and political messages of science-centred ambition by President Macky Sall of Senegal and Rwandan President Paul Kagame. But from the outset, as seasoned conference attendees agreed, it was the young scientists who were the freshest and most compelling feature of the event. They presented work on a three-wheeled tractor that can negotiate the muddy tracks that make up many of Africa’s rural roads, and can thresh maize (corn) and pump water for irrigation; and a theoretical model for the dark energy that drives the Universe’s accelerating expansion. They are researching new preventive treatments for cardiovascular diseases that are highly prevalent in black populations, and the fundamentals of semantic data-analysis. They are working towards databases that use artificial intelligence to generate their own hypotheses. And more. The meeting was not just a showcase of what is excellent. The all‑too-familiar challenges faced by Africa’s researchers were thoroughly rehearsed, both by the Fellows and by African, European and US policy grandees who sat alongside them on panels. Neighbouring countries face drastically different challenges and have wildly unequal resources. There is inadequate public and research infrastructure and a lack of intellectual-property protection. A culture that holds that ‘science and maths are only for the best’ too often hampers teachers who wish to encourage science, and widespread assumptions that these subjects are only for boys dissuade girls from pursuing science, and present discriminatory obstacles to female researchers. Despite the challenges, it was striking how the meeting was an expression of determination to find the gems among Africa’s researchers and support them. Particularly welcome was the sense that fundamental research is as essential as work that has direct societal applications. A capacity for fundamental science and mathematics is essential if ideas and techniques developed elsewhere are to be adapted and absorbed in African contexts. As Senegal’s research minister rightly emphasized, World Health Organization protocols for hepatitis B vaccination in Africa, originally derived in Asian settings, were changed because of feedback from African biologists. And innovations in handling partial differential equations need to be applied not only to fundamental physics, but also to water management. How to build on what was undoubtedly a successful exhibition of talent? The prime backers of the meeting are the African Institute for Mathematical Sciences — now spreading its wings in several countries from its roots in South Africa (see go.nature.com/9putdt) — and the Robert Bosch Foundation, based in Stuttgart, Germany. Both deserve credit, and would do well to ensure that the Fellows grow in number and that alumni keep coming to the forum as active members of a quasi-family. If that happens, the meeting could develop into a prestige event for those inside and outside Africa who want to understand and support the best of indigenous African research. Credit to Rwanda for hosting the next NEF in 2018. There is also an opportunity to make the most of the growing number of schemes that support younger scientists in Africa, alongside the NEF — the National Young Academies and Global Young Academy, the Africa Science Leadership Programme at the University of Pretoria (see go.nature.com/fkaq9f) and the DELTAS Africa programme of the Wellcome Trust (see go.nature.com/b23xux). The drive from the congress centre to the participants’ hotels highlighted the disparities between the rich worlds of many attendees’ home countries and the streets of Dakar. Poverty and inequality can be reduced only step by step; the step represented by this forum was significant. It showed what powerful commitment there is to be tapped in this emerging generation of young African scientists. The venture and the researchers it represents deserve strong support.
Sivanandam N.,African Institute for Mathematical Sciences
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013
The matching of our epoch of existence with the approximate equality of the dark energy and dark matter densities is an apparent further fine-tuning, beyond the already troubling 120 orders of magnitude that separate dark energy from the Planck scale. In this paper I will argue that this coincidence is not a fine-tuning problem, but instead an artifact of anthropic selection. Rather than assuming observations are equally likely in all epochs, one should insist that measurements of a quantity be typical amongst all such measurements. As a consequence, particular observations will reflect the epoch in which they are most easily made. In the specific case of cosmology, most measurements of dark energy and dark matter will be done during an epoch when large numbers of linear modes are available to observers, so we should not be surprised to be living at such a time. This idea is made precise in a particular model for the probability distribution for (ΩmΩΛ, ΩΛΩm), where it is shown that if p(r)∼[N(r)]b [where N(r) is the number of linear modes, and b is some arbitrary positive power], the probability that r is greater than its observed value of 0.4 is close to 1. Thus the cosmological coincidence is no longer problematic. © 2013 American Physical Society.
Khosravi N.,African Institute for Mathematical Sciences
Journal of Cosmology and Astroparticle Physics | Year: 2012
We generalise Weinberg's effective field theory approach to multiple-field inflation. In addition to standard terms in the Lagrangian we consider terms containing up to the fourth derivative of the scalar fields and the metric. The results illustrate the possible shapes of the interactions which will yield non-Gaussianity. Generally we find that the speed of sound differs from, but is close to unity, however large non-Gaussianities are possible in the multi-field case. The non-Gaussianity of the adiabatic mode and the entropy mode are correlated in shape and amplitude with the amount of the non-Gaussianity depending on the curvature of the classical field path in phase-space. We emphasize that in general the time derivative of adiabatic and entropy perturbations do not invariant due to the shift symmetry. However we find two specific combinations of them are invariant under such a symmetry and these combinations should be employed to construct an effective field theory of multi-field inflation. © 2012 IOP Publishing Ltd and Sissa Medialab srl.
Khosravi N.,African Institute for Mathematical Sciences
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2014
What is the right way to interpret a massive graviton? We generalize the kinematical framework of general relativity to multiple connections. The average of the connections is itself a connection and plays the role of the canonical connection in standard general relativity. At the level of dynamics, the simplest choice of the Einstein-Hilbert action is indistinguishable from the single-connection case. However, inspired by Weyl geometry, we show how one can construct massive gravity to all orders in perturbation theory compatible with the de Rham-Gabadadze-Tolley ghost-free model. We conclude that the mass of the graviton can be interpreted as a geometrical property of spacetime arising from two connections. Furthermore, in the multiconnection framework there is no ambiguity in the definition of the physical metric and consequently coupling to matter. © 2014 American Physical Society.
News Article | March 13, 2016
Here are three of the best: Bangura developed a civilian drone system to deliver medical supplies and transport clinical samples as part of his PhD in aerial robotics. He hopes to roll out the project first in his home country and then across hard-to-reach areas in Africa. "It's very reliable and robust, an open source system which anyone can develop," he said. "I thought about giving back to Sierra Leone and Africa, where I come from... one thing I realised is there is a very poor healthcare delivery system." During the Ebola crisis, the first two hotspots were in the eastern towns of Kailahun and Kenema, linked by an extremely poor road that meant a distance of 100 kilometres (62 miles) could take a day's travel. "In both Kailahun and Kenema, the greatest need was for more treatment facilities backed by greater and faster laboratory support," the World Health Organization said in a report during the outbreak. "The cheapest and most efficient way would be to use civilian drones," Bangura told AFP, to ship medical supplies, blood donations, and getting tests to mobile laboratories. Bangura hopes his drones will take off within 18 months, subject to government legislation. Software engineer Tabot has already received seed money from the Nelson Mandela African Institute of Science and Technology for his team's smart wristband, which works with mobile technology to provide real-time care for expectant mothers. Maternal sepsis is the third leading cause of maternal deaths in Africa, where more women die in childbirth than anywhere else, and Tabot says his invention is aimed at women in rural areas who are largely illiterate. It "does not require any behavioural change on the part of the primary user," working without messaging or apps, which usually require some reading ability, Tabot said. A combination of voice commands and Radio Frequency Identification technology, previously used to register voters in Nigeria, holds data on vital signs from regular check-ups on the device, tentatively priced at $1.50. "Every time she comes back to the local health centre the wristband is accessed and if there are any changes then that is registered again and synchronised back into the cloud," Tabot told AFP. "These women are illiterate, a good number are in rural areas so they don't even know (sepsis) is a problem," he said, adding the wristbands will trial first in Nigeria. Any problem or discomfort can be registered by the expectant mother with a health practitioner via a missed call. Thiam is still studying for his PhD at Canada's University of Ottawa, but is already forming links with government agencies back home to sell his special brand of building material created from plastic waste. With expertise also built up as an alumni of Senegal's African Institute for Mathematical Sciences (AIMS), Thiam wants to improve the environment in rapidly growing African cities while tackling pollution. "Long-term I want to be in Mali and West Africa," he said. Mixing the surplus plastic with gravel and sand in a special oven results in a product that could be used for interior design or even roads, offering a cheap and sustainable alternative to concrete, he said. "We don't have (proper planning) in our urbanisation strategies," he told AFP. "Maybe we have the text, but when we come to the application we don't have enough. "What we are trying to do is build some new, innovative material," he added. Explore further: Rwanda hopes to use drones to deliver medical supplies