2,108 research outputs found
Log canonical thresholds of Del Pezzo Surfaces in characteristic p
The global log canonical threshold of each non-singular complex del Pezzo
surface was computed by Cheltsov. The proof used Koll\'ar-Shokurov's
connectedness principle and other results relying on vanishing theorems of
Kodaira type, not known to be true in finite characteristic.
We compute the global log canonical threshold of non-singular del Pezzo
surfaces over an algebraically closed field. We give algebraic proofs of
results previously known only in characteristic . Instead of using of the
connectedness principle we introduce a new technique based on a classification
of curves of low degree. As an application we conclude that non-singular del
Pezzo surfaces in finite characteristic of degree lower or equal than are
K-semistable.Comment: 21 pages. Thorough rewrite following referee's suggestions. To be
published in Manuscripta Mathematic
Current distribution and giant magnetoimpedance in composite wires with helical magnetic anisotropy
The giant magnetoimpedance effect in composite wires consising of a
non-magnetic inner core and soft magnetic shell is studied theoretically. It is
assumed that the magnetic shell has a helical anisotropy. The current and field
distributions in the composite wire are found by means of a simultaneous
solution of Maxwell equations and the Landau-Lifshitz equation. The expressions
for the diagonal and off-diagonal impedance are obtained for low and high
frequencies. The dependences of the impedance on the anisotropy axis angle and
the shell thickness are analyzed. Maximum field sensitivity is shown to
correspond to the case of the circular anisotropy in the magnetic shell. It is
demonstrated that the optimum shell thickness to obtain maximum impedance ratio
is equal to the effective skin depth in the mahnetic material.Comment: 23 pages, 7 figure
Determination of barrier heights and prefactors from protein folding rate data
We determine both barrier heights and prefactors for protein folding by
applying constraints determined from experimental rate measurements to a
Kramers theory for folding rate. The theoretical values are required to match
the experimental values at two conditions of temperature and denaturant that
induce the same stability. Several expressions for the prefactor in the Kramers
rate equation are examined: a random energy approximation, a correlated energy
approximation, and an approximation using a single Arrhenius activation energy.
Barriers and prefactors are generally found to be large as a result of
implementing this recipe, i.e. the folding landscape is cooperative and smooth.
Interestingly, a prefactor with a single Arrhenius activation energy admits no
formal solution.Comment: 11 pages, 5 figures, 1 table, Accepted Biophys
Mechanical durability of hydrophobic surfaces fabricated by injection moulding of laser-induced textures
YesThe paper reports an investigation on the mechanical durability of textured thermoplastic surfaces together with their respective wetting properties. A range of laser-induced topographies with different aspect ratios from micro to nanoscale were fabricated on tool steel inserts using an ultrashort pulsed near infrared laser. Then, through micro-injection moulding the topographies were replicated onto polypropylene surfaces and their durability was studied systematically. In particular, the evolution of topographies on textured thermoplastic surfaces together with their wetting properties were investigated after undergoing a controlled mechanical abrasion, i.e. reciprocating dry and wet cleaning cycles. The obtained empirical data was used both to study the effects of cleaning cycles and also to identify cleaning procedures with a minimal impact on textured thermoplastic surfaces and their respective wetting properties. In addition, the use of 3D areal parameters that are standardised and could be obtained readily with any state-of-the-art surface characterisation system are discussed for monitoring the surfaces' functional response.European Commission H2020 ITN programme “European ESRs Network on Short Pulsed Laser Micro/Nanostructuring of Surfaces for Improved Functional Applications” (Laser4Fun) under the Marie Skłodowska-Curie grant agreement No. 675063 (www.laser4fun.eu) and the UKIERI DST programme “Surface functionalisation for food, packaging, and healthcare applications”. In addition, the work was supported by three other H2020 programmes, i.e. the projects on “Modular laser based additive manufacturing platform for large scale industrial applications” (MAESTRO), “High-Impact Injection Moulding Platform for mass-production of 3D and/or large micro-structured surfaces with Antimicrobial, Self-cleaning, Anti-scratch, Anti-squeak and Aesthetic functionalities” (HIMALAIA) and “Process Fingerprint for Zero-defect Net-shape Micromanufacturing” (MICROMAN)
Coherent two pion photoproduction on 12C
We develop the formalism for coherent two pion photoproduction in nuclei and
perform actual calculations of cross sections for and
photoproduction on . We find that due to the isospin symmetry the cross
section for production is very small and has a maximum when the
pions propagate together. However, the kinematical region where the energies
and polar angles of the two mesons are equal and their relative
azimuthal angle is forbidden. Conversely in the
production the pions prefer to have a relative azimuthal angle 180 and the
production of the pions propagating together is suppressed. The dominant
one-body mechanism in both channels is related to the excitation of the
isobar. Hence the reaction can serve as a source of information about
's properties in nucleus. We have found that the reaction is sensitive
to effects of the pion and renormalization in the nuclear medium,
similar to those found in the coherent reaction, but magnified
because of the presence of the two pions.Comment: 17 pages LATEX and 11 postscript figure
República: Año III Número 387 - (14/11/33)
PURPOSE OF REVIEW: The purpose of this study was to investigate the association of 26 inflammatory biomarkers (acute phase proteins, cytokines, chemokines) and renal markers with coronary lipid core burden index (LCBI) assessed by near-infrared spectroscopy (NIRS) imaging, as well as the association of these biomarkers with long-term cardiovascular outcome. RECENT FINDINGS: NIRS-derived LCBI has recently been shown to be an independent predictor of major adverse cardiac events (MACE). However, studies on the association between circulating biomarkers and NIRS-derived characteristics have not yet been performed. Between 2008 and 2011, 581 patients underwent diagnostic coronary angiography or percutaneous coronary intervention for stable angina pectoris or acute coronary syndrome (ACS). NIRS of a non-culprit vessel was performed in a subset of 203 patients. In multivariable analyses, TNF-alpha tended to be associated with higher LCBI (beta 0.088 ln (pg/ml) increase per unit LCBI; 95% CI 0.000-0.177, p = 0.05) after adjustment for clinical characteristics. However, this association did not persist after Bonferroni correction (statistical threshold 0.0019). Major adverse cardiac events (MACE) were registered in 581 patients during a median follow-up time of 4.7 years (IQR: [4.2-5.6] years). After adjustment for clinical characteristics and Bonferroni correction, IL-8 (HR 1.60; 95% CI [1.18-2.17] per ln (pg/ml), p = 0.002) was borderline associated with MACE and significantly associated with all-cause mortality or ACS (HR 1.75; 95% CI [1.24-2.48] per ln (pg/ml), p = 0.0015). In conclusion, we found that IL-8 was independently associated with clinical outcome, but altogether, the multiplex panel we investigated here did not render a useful blood biomarker of high LCBI
Breaking the Glass Ceiling Philosophy and Reality: A Study of Gender Progress and Career Development in the Corporate World
With the evolving nature of the business world, it has become a modern necessity to have a diverse
workforce. As such, human resources professionals and managers must be prepared for the redesign of their
organizations to be more inclusive throughout their formal hierarchies. Although the overall attitudes have
become generally more feminist, the unfortunate reality is that women continue to face internal and external
barriers which act as a ceiling to their career development and advancement
Energy Transfer between Throats from a 10d Perspective
Strongly warped regions, also known as throats, are a common feature of the
type IIB string theory landscape. If one of the throats is heated during
cosmological evolution, the energy is subsequently transferred to other throats
or to massless fields in the unwarped bulk of the Calabi-Yau orientifold. This
energy transfer proceeds either by Hawking radiation from the black hole
horizon in the heated throat or, at later times, by the decay of
throat-localized Kaluza-Klein states. In both cases, we calculate in a 10d
setup the energy transfer rate (respectively decay rate) as a function of the
AdS scales of the throats and of their relative distance. Compared to existing
results based on 5d models, we find a significant suppression of the energy
transfer rates if the size of the embedding Calabi-Yau orientifold is much
larger than the AdS radii of the throats. This effect can be partially
compensated by a small distance between the throats. These results are
relevant, e.g., for the analysis of reheating after brane inflation. Our
calculation employs the dual gauge theory picture in which each throat is
described by a strongly coupled 4d gauge theory, the degrees of freedom of
which are localized at a certain position in the compact space.Comment: 25 pages; a comment adde
Beauty is Attractive: Moduli Trapping at Enhanced Symmetry Points
We study quantum effects on moduli dynamics arising from the production of
particles which are light at special points in moduli space. The resulting
forces trap the moduli at these points, which often exhibit enhanced symmetry.
Moduli trapping occurs in time-dependent quantum field theory, as well as in
systems of moving D-branes, where it leads the branes to combine into stacks.
Trapping also occurs in an expanding universe, though the range over which the
moduli can roll is limited by Hubble friction. We observe that a scalar field
trapped on a steep potential can induce a stage of acceleration of the
universe, which we call trapped inflation. Moduli trapping ameliorates the
cosmological moduli problem and may affect vacuum selection. In particular,
rolling moduli are most powerfully attracted to the points with the largest
number of light particles, which are often the points of greatest symmetry.
Given suitable assumptions about the dynamics of the very early universe, this
effect might help to explain why among the plethora of possible vacuum states
of string theory, we appear to live in one with a large number of light
particles and (spontaneously broken) symmetries. In other words, some of the
surprising properties of our world might arise not through pure chance or
miraculous cancellations, but through a natural selection mechanism during
dynamical evolution.Comment: 50 pages, 4 figures; v2: added references and an appendix describing
a related classical proces
Attitudes and perceptions of next-of-kin/loved ones toward end-of-life HIV cure-related research: A qualitative focus group study in Southern California
As end-of-life (EOL) HIV cure-related research expands, understanding perspectives of participants’ next-of-kin (NOK) is critical to maintaining ethical study conduct. We conducted two small focus groups and two one-on-one interviews using focus group guides with the NOK of Last Gift study participants at the University of California, San Diego (UCSD). Participating NOK included six individuals (n = 5 male and n = 1 female), including a grandmother, grandfather, partner, spouse, and two close friends. Researchers double-coded the transcripts manually for overarching themes and sub-themes using an inductive approach. We identified six key themes: 1) NOK had an accurate, positive understanding of the Last Gift clinical study; 2) NOK felt the study was conducted ethically; 3) Perceived benefits for NOK included support navigating the dying/grieving process and personal growth; 4) Perceived drawbacks included increased sadness, emotional stress, conflicted wishes between NOK and study participants, and concerns around potential invasiveness of study procedures at the EOL; 5) NOK expressed pride in loved ones’ altruism; and 6) NOK provided suggestions to improve the Last Gift study, including better communication between staff and themselves. These findings provide a framework for ethical implementation of future EOL HIV cure-related research involving NOK
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