Since the discovery of spin glasses in dilute magnetic systems, their study has been largely focused on understanding randomness and defects as the driving mechanism. The same paradigm has also been ...applied to explain glassy states found in dense frustrated systems. Recently, however, it has been theoretically suggested that different mechanisms, such as quantum fluctuations and topological features, may induce glassy states in defect-free spin systems, far from the conventional dilute limit. Here we report experimental evidence for the existence of a glassy state, that we call a spin jam, in the vicinity of the clean limit of a frustrated magnet, which is insensitive to a low concentration of defects. We have studied the effect of impurities on SrCr9pGa12-9pO19 (SCGO(p)), a highly frustrated magnet, in which the magnetic Cr3+ (s=3/2) ions form a quasi-two-dimensional triangular system of bi-pyramids. Our experimental data shows that as the nonmagnetic Ga3+ impurity concentration is changed, there are two distinct phases of glassiness: a distinct exotic glassy state, which we call a "spin jam", for high magnetic concentration region (p>0.8) and a cluster spin glass for lower magnetic concentration, (p<0.8). This observation indicates that a spin jam is a unique vantage point from which the class of glassy states in dense frustrated magnets can be understood.
The most commonly deployed web service applications employ client-server communication patterns, with clients running remotely and services hosted in data centers. In this paper, we make the case for ...Service-Oriented Collaboration applications that combine service-hosted data with collaboration features implemented using peer-to-peer protocols. Collaboration features are awkward to support solely based on the existing web services technologies. Indirection through the data center introduces high latencies and limits scalability, and precludes collaboration between clients connected to one-another but lacking connectivity to the data center. Cornellpsilas Live Distributed Objects platform combines web services with direct peer-to-peer communication to eliminate these issues.
We present results from deep observations towards the Cygnus region using 300 hours of very-high-energy (VHE) \(\gamma\)-ray data taken with the VERITAS Cherenkov telescope array and over seven years ...of high-energy \(\gamma\)-ray data taken with the Fermi satellite at an energy above 1 GeV. As the brightest region of diffuse \(\gamma\)-ray emission in the northern sky, the Cygnus region provides a promising area to probe the origins of cosmic rays. We report the identification of a potential Fermi-LAT counterpart to VER J2031+415 (TeV J2032+4130), and resolve the extended VHE source VER J2019+368 into two source candidates (VER J2018+367* and VER J2020+368*) and characterize their energy spectra. The Fermi-LAT morphology of 3FGL 2021.0+4031e (the Gamma-Cygni supernova remnant) was examined and a region of enhanced emission coincident with VER J2019+407 was identified and jointly fit with the VERITAS data. By modeling 3FGL J2015.6+3709 as two sources, one located at the location of the pulsar wind nebula CTB 87 and one at the quasar QSO J2015+371, a continuous spectrum from 1 GeV to 10 TeV was extracted for VER J2016+371 (CTB 87). An additional 71 locations coincident with Fermi-LAT sources and other potential objects of interest were tested for VHE \(\gamma\)-ray emission, with no emission detected and upper limits on the differential flux placed at an average of 2.3% of the Crab Nebula ux. We interpret these observations in a multiwavelength context and present the most detailed \(\gamma\)-ray view of the region to date.
We present results from deep observations toward the Cygnus region using 300 hr of very high energy (VHE) γ-ray data taken with the VERITAS Cerenkov telescope array and over 7 yr of high-energy γ-ray ...data taken with the Fermi satellite at an energy above 1 GeV. As the brightest region of diffuse γ-ray emission in the northern sky, the Cygnus region provides a promising area to probe the origins of cosmic rays. We report the identification of a potential Fermi-LAT counterpart to VER J2031+415 (TeV J2032+4130) and resolve the extended VHE source VER J2019+368 into two source candidates (VER J2018+367* and VER J2020+368*) and characterize their energy spectra. The Fermi-LAT morphology of 3FGL J2021.0+4031e (the Gamma Cygni supernova remnant) was examined, and a region of enhanced emission coincident with VER J2019+407 was identified and jointly fit with the VERITAS data. By modeling 3FGL J2015.6+3709 as two sources, one located at the location of the pulsar wind nebula CTB 87 and one at the quasar QSO J2015+371, a continuous spectrum from 1 GeV to 10 TeV was extracted for VER J2016+371 (CTB 87). An additional 71 locations coincident with Fermi-LAT sources and other potential objects of interest were tested for VHE γ-ray emission, with no emission detected and upper limits on the differential flux placed at an average of 2.3% of the Crab Nebula flux. We interpret these observations in a multiwavelength context and present the most detailed γ-ray view of the region to date.
Cardiac hypertrophy is the heart’s response to increased work, pressure, or volume overload. It begins with a compensatory phase that allows the heart to meet imposed demand through rapid expression ...of stress response genes. A decompensatory phase follows marked by additional adaptive stress response gene expression that with prolonged stress progressively turns maladaptive, leading the heart into failure. The transition from compensatory to decompensatory hypertrophy is likely to reflect changes in the transcription factors and regulatory molecules that control these programs in response to changes in stress stimuli and the status of cardiomyocytes throughout the hypertrophic process. Our laboratory has been studying the role of one such transcriptional regulatory molecule, CLP-1 (cardiac lineage protein-1), in the cellular response to hypertrophic stimuli. CLP-1, the mouse homolog of the human HEXIM1 gene, is an inhibitor of P-TEFb (transcription elongation factor b), a component of the transcriptional apparatus that controls RNA polymerase II activity and gene transcription. Knockout of the CLP-1 gene results in a severe form of hypertrophy in fetal mice suggesting that in the absence of the CLP-1 inhibitor, uninhibited P-TEFb activity may lead to unregulated expression of stress response genes and decompensatory hypertrophy. Because of its critical role in regulating the stress gene response to hypertrophic stimuli, we review our laboratory’s work on CLP-1, its control of P-TEFb under various hypertrophic conditions, and how it may play an important role in a novel gene control mechanism, called promoter proximal pausing, that ensures the rapid expression of stress response genes in response to hypertrophic stimuli.
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