12,544 research outputs found
Strongly and Weakly Unstable Anisotropic Quark-Gluon Plasma
Using explicit solutions of the QCD transport equations, we construct an
effective potential for an anisotropic quark-gluon plasma which under plausible
assumptions holds beyond the Hard Loop approximation. The configurations, which
are unstable in the linear response approach, are characterized by a negative
quadratic term of the effective potential. The signs of higher order terms can
be either negative or positive, depending on the parton momentum distribution.
In the case of a Gaussian momentum distribution, the potential is negative and
unbound from below. Therefore, the modes, which are unstable for gauge fields
of small amplitude, remain unstable for arbitrary large amplitudes. We also
present an example of a momentum distribution which gives a negative quadratic
term of the effective potential but the whole potential has a minimum and it
grows for sufficiently large gauge fields. Then, the system is weakly unstable.
The character of the instability is important for the dynamical evolution of
the plasma system.Comment: 13 pages, 1 figure, revised, to appear in Phys. Rev.
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Agency, Liberation, and Intersectionality among Latina Scholars: Narratives from a Cross-institutional Writing Collective
Among United States residents, the number of doctoral degrees conferred to Latinx students represents a small percentage compared to other groups. For example, from 2009–2010, the percentage of degrees conferred to Latinx students was 5 percent compared to 74 percent for White students, 11 percent for Asian/Pacific Islanders, 7 percent for African Americans, and 0.7 percent for Indian/Alaska Natives. During the same period, the proportion of doctoral degrees conferred to females was 55 percent for Latinas compared to 65 percent for African American students, 56 percent for Asian/Pacific students, 54 percent for American Indian/Alaska Native students, and 51 percent for White female students (National Center for Education Statistics). Historically, underrepresented minority (URM) students encounter a plethora of issues that influence their educational experiences, yet there is a scarcity of scholarship that elucidates the quality of experience of women of color (WOC) pursuing doctorate degrees (Aryan and Guzman). As multi-marginalized, firstgeneration college students, we continuously struggle to find a place within higher education. Our educational pathways to becoming doctoral recipients have occurred primarily within the context of alienation, significantly influencing our need to connect with other WOC who have also felt isolated and disconnected. Consequently, we needed to find each other because knowing that there were other Latinas in doctoral programs, and actually getting to know them, validated our existence within academiaUniversity Writing Cente
Data Reductions and Combinatorial Bounds for Improved Approximation Algorithms
Kernelization algorithms in the context of Parameterized Complexity are often
based on a combination of reduction rules and combinatorial insights. We will
expose in this paper a similar strategy for obtaining polynomial-time
approximation algorithms. Our method features the use of
approximation-preserving reductions, akin to the notion of parameterized
reductions. We exemplify this method to obtain the currently best approximation
algorithms for \textsc{Harmless Set}, \textsc{Differential} and
\textsc{Multiple Nonblocker}, all of them can be considered in the context of
securing networks or information propagation
Indicators for urban quality evaluation at district scale and relationships with health and wellness perception
The paper is related with a research that was aimed to better define urban quality and sustainability
at a district scale (4000-10000 inhabitants), specifically referred to European towns and settlements.
An innovative set of indicators (72) has been developed, starting from and taking into consideration
also existing literature, both in terms of indicators and sets of indicators (OECD, UN, Agenda 21, and
existing European databases as CRISP), four “thematic” areas have been defined dealing with
architectural quality, accessibility, environment and services. Within each of these areas some macroindicators
and micro-indicators have been defined. The aim is to translate something that is usually
considered subjective into something “objective” and finally defined with a number (0-100). Microindicators
and macro-indicators are weighted thanks to a mathematical method based on symmetrical
matrixes, so that there is a correct balance between different areas. Indicators are both qualitative
and quantitative, so they are not just referred to urban planning procedures. The research has been
already successfully applied to some Italian districts in towns as Lodi, Genova and Milano. The set of
indicators was needed also to work within a multi disciplinary team that has already included
engineers, architects, planners as well as doctors and physicians. As a matter of fact the results in
terms of urban quality have been compared with medical results concerning health and wellness
perception (using SF-36 international recognized questionnaires) by users (inhabitants), finding (non
linear) relationships between urban quality and well being perception by inhabitants. The results of
this research can be used to: better define design strategies (by designers) accordingly to users
wellness, or evaluate ex-post the results of design activities (by municipalities or public authorities)
A dynamical collective calculation of supernova neutrino signals
We present the first calculations with three flavors of collective and shock
wave effects for neutrino propagation in core-collapse supernovae using
hydroynamical density profiles and the S matrix formalism. We explore the
interplay between the neutrino-neutrino interaction and the effects of multiple
resonances upon the time signal of positrons in supernova observatories. A
specific signature is found for the inverted hierarchy and a large third
neutrino mixing angle and we predict, in this case, a dearth of lower energy
positrons in Cherenkov detectors midway through the neutrino signal and the
simultaneous revelation of valuable information about the original fluxes. We
show that this feature is also observable with current generation neutrino
detectors at the level of several sigmas.Comment: 4 pages, 5 figure
Do interactions between plant roots and the rhizosphere affect parasitoid behaviour?
Multitrophic interactions are powerful forces shaping the structure of living communities. Plants encounter a great diversity of organisms in their environment: some of these interactions are beneficial (e.g. symbiotic fungi and insect pollinators) while some are detrimental (e.g. herbivorous insects and pathogenic micro-organisms). Multitrophic interactions between below-ground and above-ground organisms are receiving increasing attention because they may influence plant defences against biotic and abiotic stresses. In this study we show that an arbuscular mycorrhizal symbiosis makes tomato plants significantly more resistant towards aphids, by enhancing both direct defences, both attractivity towards aphid parasitoids
Fat residue and use-wear found on Acheulian biface and scraper associated with butchered elephant remains at the site of Revadim, Israel
The archaeological record indicates that elephants must have played a significant role in early human diet and culture during Palaeolithic times in the Old World. However, the nature of interactions between early humans and elephants is still under discussion. Elephant remains are found in Palaeolithic sites, both open-air and cave sites, in Europe, Asia, the Levant, and Africa. In some cases elephant and mammoth remains indicate evidence for butchering and marrow extraction performed by humans. Revadim Quarry (Israel) is a Late Acheulian site where elephant remains were found in association with characteristic Lower Palaeolithic flint tools. In this paper we present results regarding the use of Palaeolithic tools in processing animal carcasses and rare identification of fat residue preserved on Lower Palaeolithic tools. Our results shed new light on the use of Palaeolithic stone tools and provide, for the first time, direct evidence (residue) of animal exploitation through the use of an Acheulian biface and a scraper. The association of an elephant rib bearing cut marks with these tools may reinforce the view suggesting the use of Palaeolithic stone tools in the consumption of large game
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