Entropy of three-dimensional asymptotically flat cosmological solutions

The thermodynamics of three-dimensional asymptotically flat cosmological solutions that play the same role than the BTZ black holes in the anti-de Sitter case is derived and explained from holographic properties of flat space. It is shown to coincide with the flat-space limit of the thermodynamics of the inner black hole horizon on the one hand and the semi-classical approximation to the gravitational partition function associated to the entropy of the outer horizon on the other. This leads to the insight that it is the Massieu function that is universal in the sense that it can be computed at either horizon.Comment: 16 pages Latex file, v2: references added, cosmetic changes, v3: 1 reference adde

Fourier Magnetic Imaging with Nanoscale Resolution and Compressed Sensing Speed-up using Electronic Spins in Diamond

Optically-detected magnetic resonance using Nitrogen Vacancy (NV) color centres in diamond is a leading modality for nanoscale magnetic field imaging, as it provides single electron spin sensitivity, three-dimensional resolution better than 1 nm, and applicability to a wide range of physical and biological samples under ambient conditions. To date, however, NV-diamond magnetic imaging has been performed using real space techniques, which are either limited by optical diffraction to 250 nm resolution or require slow, point-by-point scanning for nanoscale resolution, e.g., using an atomic force microscope, magnetic tip, or super-resolution optical imaging. Here we introduce an alternative technique of Fourier magnetic imaging using NV-diamond. In analogy with conventional magnetic resonance imaging (MRI), we employ pulsed magnetic field gradients to phase-encode spatial information on NV electronic spins in wavenumber or k-space followed by a fast Fourier transform to yield real-space images with nanoscale resolution, wide field-of-view (FOV), and compressed sensing speed-up.Comment: 31 pages, 10 figure

Comparative overwiew of brain perfusion imaging techniques

Background and Purpose - Numerous imaging techniques have been developed and applied to evaluate brain hemodynamics. Among these are positron emission tomography, single photon emission computed tomography, Xenon-enhanced computed tomography, dynamic perfusion computed tomography, MRI dynamic susceptibility contrast, arterial spin labeling, and Doppler ultrasound. These techniques give similar information about brain hemodynamics in the form of parameters such as cerebral blood flow or cerebral blood volume. All of them are used to characterize the same types of pathological conditions. However, each technique has its own advantages and drawbacks. Summary of Review - This article addresses the main imaging techniques dedicated to brain hemodynamics. It represents a comparative overview established by consensus among specialists of the various techniques. Conclusions - For clinicians, this article should offer a clearer picture of the pros and cons of currently available brain perfusion imaging techniques and assist them in choosing the proper method for every specific clinical setting

Comparative overview of brain perfusion imaging techniques Epub

Background and Purpose - Numerous imaging techniques have been developed and applied to evaluate brain hemodynamics. Among these are positron emission tomography, single photon emission computed tomography, Xenon-enhanced computed tomography, dynamic perfusion computed tomography, MRI dynamic susceptibility contrast, arterial spin labeling, and Doppler ultrasound. These techniques give similar information about brain hemodynamics in the form of parameters such as cerebral blood flow or cerebral blood volume. All of them are used to characterize the same types of pathological conditions. However, each technique has its own advantages and drawbacks. Summary of Review - This article addresses the main imaging techniques dedicated to brain hemodynamics. It represents a comparative overview established by consensus among specialists of the various techniques. Conclusions - For clinicians, this article should offer a clearer picture of the pros and cons of currently available brain perfusion imaging techniques and assist them in choosing the proper method for every specific clinical setting

A massive, quiescent galaxy at redshift of z=3.717

In the early Universe finding massive galaxies that have stopped forming stars present an observational challenge as their rest-frame ultraviolet emission is negligible and they can only be reliably identified by extremely deep near-infrared surveys. These have revealed the presence of massive, quiescent early-type galaxies appearing in the universe as early as z$\sim$2, an epoch 3 Gyr after the Big Bang. Their age and formation processes have now been explained by an improved generation of galaxy formation models where they form rapidly at z$\sim$3-4, consistent with the typical masses and ages derived from their observations. Deeper surveys have now reported evidence for populations of massive, quiescent galaxies at even higher redshifts and earlier times, however the evidence for their existence, and redshift, has relied entirely on coarsely sampled photometry. These early massive, quiescent galaxies are not predicted by the latest generation of theoretical models. Here, we report the spectroscopic confirmation of one of these galaxies at redshift z=3.717 with a stellar mass of 1.7$\times$10$^{11}$ M$_\odot$ whose absorption line spectrum shows no current star-formation and which has a derived age of nearly half the age of the Universe at this redshift. The observations demonstrates that the galaxy must have quickly formed the majority of its stars within the first billion years of cosmic history in an extreme and short starburst. This ancestral event is similar to those starting to be found by sub-mm wavelength surveys pointing to a possible connection between these two populations. Early formation of such massive systems is likely to require significant revisions to our picture of early galaxy assembly.Comment: 6 pages, 7 figures. This is the final preprint corresponding closely to the published version. Uploaded 6 months after publication in accordance with Nature polic

Salmo salar and Esox lucius full-length cDNA sequences reveal changes in evolutionary pressures on a post-tetraploidization genome

<p>Abstract</p> <p>Background</p> <p>Salmonids are one of the most intensely studied fish, in part due to their economic and environmental importance, and in part due to a recent whole genome duplication in the common ancestor of salmonids. This duplication greatly impacts species diversification, functional specialization, and adaptation. Extensive new genomic resources have recently become available for Atlantic salmon (<it>Salmo salar</it>), but documentation of allelic versus duplicate reference genes remains a major uncertainty in the complete characterization of its genome and its evolution.</p> <p>Results</p> <p>From existing expressed sequence tag (EST) resources and three new full-length cDNA libraries, 9,057 reference quality full-length gene insert clones were identified for Atlantic salmon. A further 1,365 reference full-length clones were annotated from 29,221 northern pike (<it>Esox lucius</it>) ESTs. Pairwise d_N/d_Scomparisons within each of 408 sets of duplicated salmon genes using northern pike as a diploid out-group show asymmetric relaxation of selection on salmon duplicates.</p> <p>Conclusions</p> <p>9,057 full-length reference genes were characterized in <it>S. salar </it>and can be used to identify alleles and gene family members. Comparisons of duplicated genes show that while purifying selection is the predominant force acting on both duplicates, consistent with retention of functionality in both copies, some relaxation of pressure on gene duplicates can be identified. In addition, there is evidence that evolution has acted asymmetrically on paralogs, allowing one of the pair to diverge at a faster rate.</p

Lessons for Medicare Part D in the hemodialysis community

BACKGROUND: Medicare beneficiaries without prescription drug coverage consistently fill fewer prescriptions than beneficiaries with some form of drug coverage due to cost. ESRD patients, who are disproportionately poor and typically use multiple oral medications, would likely benefit substantially from any form of prescription drug coverage. Because most hemodialysis patients are Medicare-eligible, they as well as their providers would be expected to be well informed of changes in Medicare prescription drug coverage. By examining the level of understanding and use of the temporary Medicare Prescription Drug Discount Card Program in the hemodialysis population, we can gain a better understanding of the potential long-term utilization for Medicare Part D. METHODS: We surveyed English-speaking adult hemodialysis patients with Medicare coverage from two urban hemodialysis centers affiliated with the University of California San Francisco (UCSF) during July and August 2005 (n = 70). We also surveyed University- and community-based nephrologists and non-physician dialysis health care professionals over the same time frame (n = 70). RESULTS: Fifty-nine percent of patients received prescription drug coverage through Medi-Cal, 20% through another insurance program, and 21% had no prescription drug coverage. Forty percent of patients with no prescription drug coverage reported "sometimes" or "rarely" being able to obtain medications vs. 22% of patients with some form of drug coverage. None of the patients surveyed actually had a Medicare-approved prescription drug card, and of those who intended to apply, only 10% reported knowing how to do so. Only 11% health care professionals knew the eligibility requirements of the drug discount cards. CONCLUSION: Despite a significant need, hemodialysis patients and providers were poorly educated about the Medicare Prescription Drug Discount Cards. This has broad implications for the dissemination of information about Medicare Part D

Post-radiation dedifferentiation of meningioma into osteosarcoma.

BACKGROUND: A number of osteoblastic meningiomas, primary osteosarcomas of the meninges, and post-radiation osteosarcomas of the head have been reported. However, postradiation dedifferentiation of meningioma into osteosarcoma has not been reported previously. CASE PRESENTATION: In 1987 a caucasian man, then 38 years old, presented with a pituitary macroadenoma. He underwent a subtotal resection of the tumor and did well until 1990 when a recurrent tumor was diagnosed. This was treated with subtotal resection of the tumor, followed by radiation therapy for six weeks to a total of 54 Gy. He was considered "disease-free" for nearly ten years. However, most recently in July 2000, he presented with a visual field deficit due to a second recurrence of his pituitary macroadenoma, now with suprasellar extension. At this time, as an incidental finding, a mass attached to the dura was noted in the left parietal hemisphere. This dura–based mass had grown rapidly by January 2001 and was excised. It showed histological, immunohistochemical, and electron microscopic features of malignant meningioma and osteosarcoma with a sharp demarcation between the two components. CONCLUSIONS: We report a rare case of a radiation induced dedifferentiation of meningioma into osteosarcoma, which has not been reported previously

Therapeutic DNA vaccine induces broad T cell responses in the gut and sustained protection from viral rebound and AIDS in SIV-infected rhesus macaques.

Immunotherapies that induce durable immune control of chronic HIV infection may eliminate the need for life-long dependence on drugs. We investigated a DNA vaccine formulated with a novel genetic adjuvant that stimulates immune responses in the blood and gut for the ability to improve therapy in rhesus macaques chronically infected with SIV. Using the SIV-macaque model for AIDS, we show that epidermal co-delivery of plasmids expressing SIV Gag, RT, Nef and Env, and the mucosal adjuvant, heat-labile E. coli enterotoxin (LT), during antiretroviral therapy (ART) induced a substantial 2-4-log fold reduction in mean virus burden in both the gut and blood when compared to unvaccinated controls and provided durable protection from viral rebound and disease progression after the drug was discontinued. This effect was associated with significant increases in IFN-γ T cell responses in both the blood and gut and SIV-specific CD8+ T cells with dual TNF-α and cytolytic effector functions in the blood. Importantly, a broader specificity in the T cell response seen in the gut, but not the blood, significantly correlated with a reduction in virus production in mucosal tissues and a lower virus burden in plasma. We conclude that immunizing with vaccines that induce immune responses in mucosal gut tissue could reduce residual viral reservoirs during drug therapy and improve long-term treatment of HIV infection in humans