1,519 research outputs found
Partial Supergravity Breaking and the Effective Action of Consistent Truncations
We study vacua of N = 4 half-maximal gauged supergravity in five dimensions
and determine crucial properties of the effective theory around the vacuum. The
main focus is on configurations with exactly two broken supersymmetries, since
they frequently appear in consistent truncations of string theory and
supergravity. Evaluating one-loop corrections to the Chern-Simons terms we find
necessary conditions to ensure that a consistent truncation also gives rise to
a proper effective action of an underlying more fundamental theory. To obtain
concrete examples, we determine the N=4 action of M-theory on six-dimensional
SU(2)-structure manifolds with background fluxes. Calabi-Yau threefolds with
vanishing Euler number are examples of SU(2)-structure manifolds that yield N=2
Minkowski vacua. We find that that one-loop corrections to the Chern-Simons
terms vanish trivially and thus do not impose constraints on identifying
effective theories. This result is traced back to the absence of isometries on
these geometries. Examples with isometries arise from type IIB supergravity on
squashed Sasaki-Einstein manifolds. In this case the one-loop gauge
Chern-Simons terms vanish due to non-trivial cancellations, while the one-loop
gravitational Chern-Simons terms are non-zero.Comment: 44 pages, v2: minor changes, references adde
Quantifying the benefit of a proteome reserve in fluctuating environments.
The overexpression of proteins is a major burden for fast-growing bacteria. Paradoxically, recent characterization of the proteome of Escherichia coli found many proteins expressed in excess of what appears to be optimal for exponential growth. Here, we quantitatively investigate the possibility that this overexpression constitutes a strategic reserve kept by starving cells to quickly meet demand upon sudden improvement in growth conditions. For cells exposed to repeated famine-and-feast cycles, we derive a simple relation between the duration of feast and the allocation of the ribosomal protein reserve to maximize the overall gain in biomass during the feast
The Half-lives of La and La
The half-lives of La and La were determined via gamma
spectroscopy and high-precision ionization chamber measurements. The results
are 18.930(6) h for La and 4.59(4) h for La compared to the
previously compiled values of 19.5(2) h and 4.8(2) h, respectively. The new
results represent an improvement in the precision and accuracy of both values.
These lanthanum isotopes comprise a medically interesting system with positron
emitter La and Auger electron emitter La forming a matched pair
for internal diagnostics and therapeutics. The precise half-lives are necessary
for proper evaluation of their value in medicine and for a more representative
tabulation of nuclear data.Comment: 11 pages, 3 figure
CRM-система как инструмент повышения эффективности деятельности компании
Объектом исследования является ООО "СМЕТ". Предметом исследования является управление взаимоотношениями с клиентами.
Цель работы – рассмотрение CRM-систем как инструмент повышения эффективности бизнеса. Актуальность работы: в новых условиях компаниям продавать свои товары и услуги и удерживать клиентов стало намного сложнее. Клиенты стали тщательнее "считать деньги", торговаться и экономить. Покупательский спрос смещается в сторону более дешевых предложений, клиенты отказываются от всего дополнительного и необязательного, сопутствующих товаров. Усиливается конкуренция на рынках внутри страны.The object of this study is LLC "ESTIMATES". The subject of this study is customer relationship management. Purpose - consideration of CRM-systems as a tool to improve business performance. Relevance of the work: under the new conditions the companies sell their products and services and hold the customer has become much more difficult. Customers have become more thoroughly "counting money" to trade and save. Consumer demand shifts toward lower-cost offerings, customers abandon all the extra and optional, related products. There is a growing competition in the domestic markets and with foreign companies
The Equity and Efficiency of Two-Part Tariffs in U.S. Natural Gas Markets
Residential natural gas customers in the United States face volumetric charges for natural gas that average about 30% more than marginal cost. The large markup on natural gas – which is used to cover the fixed infrastructure and operating costs of the local distribution companies – is widely recognized to be inefficient. Nonetheless, attempts to reduce volumetric charges, and cover the revenue shortfall through increased fixed monthly fees, have faced opposition based on the belief that current rate schedules have desirable distributional consequences. We evaluate this claim empirically using nationally-representative household-level data. We find that natural gas consumption is weakly correlated with household income, so current rate schedules are only mildly progressive. Under current rate schedules, high-volume customers pay a disproportionately large share of fixed costs, but these exhibit a weak correlation with high-income households. The correlation is somewhat weaker still when we consider alternative indicators of household financial stress, such as poverty status or number of children in the household. We show, for example, that poor households with multiple children would receive lower bills on average under marginal cost pricing. We present evidence that one cause of the weak redistributional impact of the current pricing policy is that the poor tend to live in less energy efficient homes.
Interlaboratory comparison tests as a tool for quality improvement in fertilizer analysis methods and laboratory performance
Local formation of nitrogen-vacancy centers in diamond by swift heavy ions
We exposed nitrogen-implanted diamonds to beams of swift uranium and gold
ions (~1 GeV) and find that these irradiations lead directly to the formation
of nitrogen vacancy (NV) centers, without thermal annealing. We compare the
photoluminescence intensities of swift heavy ion activated NV- centers to those
formed by irradiation with low-energy electrons and by thermal annealing. NV-
yields from irradiations with swift heavy ions are 0.1 of yields from low
energy electrons and 0.02 of yields from thermal annealing. We discuss possible
mechanisms of NV-center formation by swift heavy ions such as electronic
excitations and thermal spikes. While forming NV centers with low efficiency,
swift heavy ions enable the formation of three dimensional NV- assemblies over
relatively large distances of tens of micrometers. Further, our results show
that NV-center formation is a local probe of (partial) lattice damage
relaxation induced by electronic excitations from swift heavy ions in diamond.Comment: to be published in Journal of Applied Physic
Neodymium-140 DOTA-LM3:Evaluation of an <i>In Vivo</i> Generator for PET with a Non-Internalizing Vector
140Nd (t1/2 = 3.4 days), owing to its short-lived positron emitting daughter 140Pr (t1/2 = 3.4 min), has promise as an in vivo generator for positron emission tomography (PET). However, the electron capture decay of 140Nd is chemically disruptive to macrocycle-based radiolabeling, meaning that an in vivo redistribution of the daughter 140Pr is expected before positron emission. The purpose of this study was to determine how the delayed positron from the de-labeled 140Pr affects preclinical imaging with 140Nd. To explore the effect, 140Nd was produced at CERN-ISOLDE, reacted with the somatostatin analogue, DOTA-LM3 (1,4,7,10- tetraazacyclododecane, 1,4,7- tri acetic acid, 10- acetamide N - p-Cl-Phecyclo(d-Cys-Tyr-d-4-amino-Phe(carbamoyl)-Lys-Thr-Cys)d-Tyr-NH2) and injected into H727 xenograft bearing mice. Comparative pre- and post-mortem PET imaging at 16 h postinjection was used to quantify the in vivo redistribution of 140Pr following 140Nd decay. The somatostatin receptor-positive pancreas exhibited the highest tissue accumulation of 140Nd-DOTA-LM3 (13% ID/g at 16 h) coupled with the largest observed redistribution rate, where 56 ± 7% (n = 4, mean ± SD) of the in situ produced 140Pr washed out of the pancreas before decay. Contrastingly, the liver, spleen, and lungs acted as strong sink organs for free 140Pr3+. Based upon these results, we conclude that 140Nd imaging with a non-internalizing vector convolutes the biodistribution of the tracer with the accumulation pattern of free 140Pr. This redistribution phenomenon may show promise as a probe of the cellular interaction with the vector, such as in determining tissue dependent internalization behavior
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