A note on dark energy induced by D-brane motion

In this note we study the possibility of obtaining dark energy solution in a D-brane scenario in a warped background that includes brane-position dependent corrections for the non-perturbative superpotential. The volume modulus is stabilized at instantaneous minima of the potential. Though the model can account for the existence of dark energy within present observational bound - fine-tuning of the model parameters becomes unavoidable. Moreover, the model does not posses a tracker solution.Comment: 5 pages, 4 figure

Above the Law: The Prosecutor\u27s Duty to Seek Justice and the Performance of Substantial Assistance Agreements

We study the gravitational-wave (GW) signatures of clouds of ultralight bosons around black holes (BHs) in binary inspirals. These clouds, which are formed via superradiance instabilities for rapidly rotating BHs, produce distinct effects in the population of BH masses and spins, and, for real fields, a continuous monochromatic GW signal. We show that the presence of a binary companion greatly enriches the dynamical evolution of the system, most remarkably through the existence of resonant transitions between the growing and decaying modes of the cloud (analogous to Rabi oscillations in atomic physics). These resonances have rich phenomenological implications for current and future GW detectors. Notably, the amplitude of the GW signal from the clouds may be reduced, and in many cases terminated, much before the binary merger. The presence of a boson cloud can also be revealed in the GW signal from the binary through the imprint of finite-size effects, such as spin-induced multipole moments and tidal Love numbers. The time dependence of the cloud's energy density during the resonance leads to a sharp feature, or at least attenuation, in the contribution from the finite-size terms to the waveforms. The observation of these effects would constrain the properties of putative ultralight bosons through precision GW data, offering new probes of physics beyond the Standard Model

Desensitizing Inflation from the Planck Scale

A new mechanism to control Planck-scale corrections to the inflationary eta parameter is proposed. A common approach to the eta problem is to impose a shift symmetry on the inflaton field. However, this symmetry has to remain unbroken by Planck-scale effects, which is a rather strong requirement on possible ultraviolet completions of the theory. In this paper, we show that the breaking of the shift symmetry by Planck-scale corrections can be systematically suppressed if the inflaton field interacts with a conformal sector. The inflaton then receives an anomalous dimension in the conformal field theory, which leads to sequestering of all dangerous high-energy corrections. We analyze a number of models where the mechanism can be seen in action. In our most detailed example we compute the exact anomalous dimensions via a-maximization and show that the eta problem can be solved using only weakly-coupled physics.Comment: 34 pages, 3 figures

The German Bight (North Sea) is a nursery area for both locally and externally produced sprat juveniles

To better understand the role of the German Bight (GB) as a nursery area for juvenile North Sea sprat Sprattus sprattus we sought to determine whether the area may receive only locally or also externally produced offspring. We sampled juveniles during 3 trawl surveys in the GB in August, September, and October 2004 and applied otolith microstructure analysis in order to reconstruct their distributions of the day-of-first-increment-formation (dif). These were contrasted with spatial and seasonal patterns of sprat egg abundance in the GB and its adjacent areas, observed during 6 monthly plankton surveys. It was found that the majority of juveniles originated mainly from April/May 2004, coinciding with high spawning activity west of the GB, whereas spawning and larval production inside the GB peaked notably later, in May/June. This indicated that a large proportion of juveniles was produced outside the GB and transported subsequently into it through passive and/or active migration. Shifts to later mean difs from one survey to the next and length distributions indicative of the simultaneous presence of multiple cohorts, supported the notion that the GB is a complex retention and nursery area for sprat offspring from different North Sea spawning grounds and times. Later born juveniles had significantly faster initial growth rates than earlier born conspecifics, which was likely temperature-mediated, given the strong correlation between back-calculated growth histories and sea surface temperature as a proxy for thermal histories of juveniles (r(2) = 0.52). (C) 2009 Elsevier B.V. All rights reserved

Structures for small scientific satellites

Structures and design for scientific satellite

Employees, Firm Size and Profitability of U.S. Manufacturing Industries

We examine the relation between firm size and profitability within 109 SIC four-digit manufacturing industries. Depending on our measure of profitability, we find that profitability increases at a decreasing rate and eventually declines in up to 47 of our industries. No relation between profitability and size is found in up to 52 of our industries. These two categories account for 97 of our 109 industries. Profitability continues to increase as firms become larger in up to 11 industries. Hence, the relation between size and profitability is industry specific. But, regardless of the shape of the size profitability function, we find that profitability is negatively correlated with the number of employees for firms of a given size measured in terms of total assets and sales. These results are puzzling in the context of work by others who report that common stock returns are negatively correlated with size when size is measured by the market value of a company or with the work of those who argue that size is a proxy for risk. Interpreted against these works, our findings may mean that large firms earn excess returns, that small firms fail to earn their cost of capital, or that accounting returns simply behave differently than market returns with respect to firm size

Evidence against the Detectability of a Hippocampal Place Code Using Functional Magnetic Resonance Imaging

Individual hippocampal neurons selectively increase their firing rates in specific spatial locations. As a population, these neurons provide a decodable representation of space that is robust against changes to sensory- and path-related cues. This neural code is sparse and distributed, theoretically rendering it undetectable with population recording methods such as functional magnetic resonance imaging (fMRI). Existing studies nonetheless report decoding spatial codes in the human hippocampus using such techniques. Here we present results from a virtual navigation experiment in humans in which we eliminated visual- and path-related confounds and statistical limitations present in existing studies, ensuring that any positive decoding results would represent a voxel-place code. Consistent with theoretical arguments derived from electrophysiological data and contrary to existing fMRI studies, our results show that although participants were fully oriented during the navigation task, there was no statistical evidence for a place code

3-D transponder antennas for future SHF RFID applications

The radio frequency identification (RFID) technology is omnipresent since a few years. Some of the most popular fields of application are the use for security tasks, for logistics and for the consumer segment. For example, chip card or key ring sized RFID transponders can allow wireless access to secured rooms. The number of applications for wireless data transmission for the identification and tracking of objects increases every year. There is a large development need for highly functional and inexpensive RFID transponders due to the ever-increasing demand on improved reliability, higher data rates and read and write ranges of the RFID systems. Therefore, research was performed on new 3-D transponder antennas for the Super High Frequency Band around 5.8 GHz. Additionally, wave propagation effects and the influence of different dielectric environments were considered. Parallel to the design of the novel antenna structures, the printing process for inexpensive manufacturing was investigated. The gained results are the basis for prospective RFID applications

Printed antennas: from theory to praxis, challenges and applications

Miniaturized, highly integrated wireless communication systems are used in many fields like logistics and mobile communications. Often multiple antenna structures are integrated in a single product. To achieve such a high level of integration the antenna structures are manufactured e.g. from flexible boards or via LDS (laser direct structuring) which allows the production of complex monopole or dipole antennas with three-dimensionally curved shapes. Main drawbacks are the sophisticated production process steps and their costs. The additive deposition of metallic inks or pastes by a printing process is an alternative manufacturing method with reduced cost. <br><br> To implement such printed antennas we investigated in the fields of antenna design, simulation, printing technology and characterization. The chosen example of use was a customized dipole antenna for a Radio Frequency Identification application. The results prove the intended functionality of the printed dipole in regard to a highly cost efficient printing manufacturing