Memory usage verification using Hip/Sleek.

Embedded systems often come with constrained memory footprints. It is therefore essential to ensure that software running on such platforms fulfils memory usage specifications at compile-time, to prevent memory-related software failure after deployment. Previous proposals on memory usage verification are not satisfactory as they usually can only handle restricted subsets of programs, especially when shared mutable data structures are involved. In this paper, we propose a simple but novel solution. We instrument programs with explicit memory operations so that memory usage verification can be done along with the verification of other properties, using an automated verification system Hip/Sleek developed recently by Chin et al.[10,19]. The instrumentation can be done automatically and is proven sound with respect to an underlying semantics. One immediate benefit is that we do not need to develop from scratch a specific system for memory usage verification. Another benefit is that we can verify more programs, especially those involving shared mutable data structures, which previous systems failed to handle, as evidenced by our experimental results

Suppression of Superconducting Critical Current Density by Small Flux Jumps in MgB2MgB_2 Thin Films

By doing magnetization measurements during magnetic field sweeps on thin films of the new superconductor $MgB_2$, it is found that in a low temperature and low field region small flux jumps are taking place. This effect strongly suppresses the central magnetization peak leading to reduced nominal superconducting critical current density at low temperatures. A borderline for this effect to occur is determined on the field-temperature (H-T) phase diagram. It is suggested that the small size of the flux jumps in films is due to the higher density of small defects and the relatively easy thermal diffusion in thin films in comparison with bulk samples.Comment: 7 figures Phys. Rev. B accepted scheduled issue: 01 Feb 200

Peptide ligands of the cardiac ryanodine receptor as super-resolution imaging probes

To study the structural basis of pathological remodelling and altered calcium channel functional states in the heart, we sought to re-purpose high-affinity ligands of the cardiac calcium channel, the ryanodine receptor (RyR2), into super-resolution imaging probes. Imperacalcin (IpCa), a scorpion toxin peptide which induces channel sub-conduction states, and DPc10, a synthetic peptide corresponding to a sequence of the RyR2, which replicates arrhythmogenic CPVT functional changes, were used in fluorescent imaging experiments. Isolated adult rat ventricular cardiomyocytes were saponin-permeabilised and incubated with each peptide. IpCa-A546 became sequestered into the mitochondria. This was prevented by treatment of the permeabilised cells with the ionophore FCCP, revealing a striated staining pattern in confocal imaging which had weak colocalisation with RyR2 clusters. Poor specificity (as an RyR2 imaging probe) was confirmed at higher resolution with expansion microscopy (proExM) (~70 nm). DPc10-FITC labelled a striated pattern, which had moderate colocalisation with RyR2 cluster labelling in confocal and proExM. There was also widespread non-target labelling of the Z-discs, intercalated discs, and nuclei, which was unaffected by incubation times or 10 mM caffeine. The inactive peptide mut-DPc10-FITC (which causes no functional effects) displayed a similar labelling pattern. Significant labelling of structures unrelated to RyR2 by both peptide conjugates makes their use as highly specific imaging probes of RyR2 in living isolated cardiomyocytes highly challenging. We investigated the native DPc10 sequence within the RyR2 structure to understand the domain interactions and proposed mechanism of peptide binding. The native DPc10 sequence does not directly interact with another domain, and but is downstream of one such domain interface. The rabbit Arg2475 (equivalent to human Arg2474, mutated in CPVT) in the native sequence is the most accessible portion and most likely location for peptide disturbance, suggesting FITC placement does not impact peptide binding

The fermi arc and fermi pocket in cuprates in a short-range diagonal stripe phase

In this paper we studied the fermi arc and the fermi pocket in cuprates in a short-range diagonal stripe phase with wave vectors $(7\pi/8, 7\pi/8)$, which reproduce with a high accuracy the positions and sizes of the fermi arc and fermi pocket and the superstructure in cuprates observed by Meng et al\cite{Meng}. The low-energy spectral function indicates that the fermi pocket results from the main band and the shadow band at the fermi energy. Above the fermi energy the shadow band gradually departs away from the main band, leaving a fermi arc. Thus we conclude that the fermi arc and fermi pocket can be fully attributed to the stripe phase but has nothing to do with pairing. Incorporating a d-wave pairing potential in the stripe phase the spectral weight in the antinodal region is removed, leaving a clean fermi pocket in the nodal region.Comment: 5 pages, 6 figure

Genotypic Resistance Tests Sequences Reveal the Role of Marginalized Populations in HIV-1 Transmission in Switzerland.

Targeting hard-to-reach/marginalized populations is essential for preventing HIV-transmission. A unique opportunity to identify such populations in Switzerland is provided by a database of all genotypic-resistance-tests from Switzerland, including both sequences from the Swiss HIV Cohort Study (SHCS) and non-cohort sequences. A phylogenetic tree was built using 11,127 SHCS and 2,875 Swiss non-SHCS sequences. Demographics were imputed for non-SHCS patients using a phylogenetic proximity approach. Factors associated with non-cohort outbreaks were determined using logistic regression. Non-B subtype (univariable odds-ratio (OR): 1.9; 95% confidence interval (CI): 1.8-2.1), female gender (OR: 1.6; 95% CI: 1.4-1.7), black ethnicity (OR: 1.9; 95% CI: 1.7-2.1) and heterosexual transmission group (OR:1.8; 95% CI: 1.6-2.0), were all associated with underrepresentation in the SHCS. We found 344 purely non-SHCS transmission clusters, however, these outbreaks were small (median 2, maximum 7 patients) with a strong overlap with the SHCS'. 65% of non-SHCS sequences were part of clusters composed of >= 50% SHCS sequences. Our data suggests that marginalized-populations are underrepresented in the SHCS. However, the limited size of outbreaks among non-SHCS patients in-care implies that no major HIV outbreak in Switzerland was missed by the SHCS surveillance. This study demonstrates the potential of sequence data to assess and extend the scope of infectious-disease surveillance

Naïve CD8 + T cell derived tumor-specific cytotoxic effectors as a potential remedy for overcoming TGF-β immunosuppression in the tumor microenvironment

Despite of the potential implications for cancer immunotherapy, conventional approaches using in vitro expanded CD8 + T cells have suboptimal outcomes, mostly due to loss of functionality from cellular exhaustion. We therefore investigated the phenotypic and functional differences among in vitro activated CD8 + T cells of three different sources, namely naïve (NT eff), memory (MT eff) and tumor-infiltrating lymphocytes (TIL eff) from human and mice, to better understand mechanisms behind potent effector functions and potential for overcoming current limitations. In line with the greater proliferation activity and longer telomere lengths of NT eff populations, cells of naïve origin exhibited significantly less amounts of T cell exhaustion markers than those of MT eff and TIL eff, and moreover, acquired distinct expression patterns of memory-promoting transcription factors, T-bet and Eomes, induced in a rapid and sustainable manner. NT eff cells appeared to have lower expression of Foxp1 and were refractory to apoptosis upon TGF-β conditioning, implying better survival potential and resistance to tumor-induced immune suppression. Of CD8 + T cell pools activated to tumor-specific CTLs, naïve cell generated effectors possessed the most potent cytotoxic activity, validating implications for use in rational design of adoptive immunotherapy11091sciescopu

On Traversable Lorentzian Wormholes in the Vacuum Low Energy Effective String Theory in Einstein and Jordan Frames

Three new classes (II-IV) of solutions of the vacuum low energy effective string theory in four dimensions are derived. Wormhole solutions are investigated in those solutions including the class I case both in the Einstein and in the Jordan (string) frame. It turns out that, of the eight classes of solutions investigated (four in the Einstein frame and four in the corresponding string frame), massive Lorentzian traversable wormholes exist in five classes. Nontrivial massless limit exists only in class I Einstein frame solution while none at all exists in the string frame. An investigation of test scalar charge motion in the class I solution in the two frames is carried out by using the Plebanski-Sawicki theorem. A curious consequence is that the motion around the extremal zero (Keplerian) mass configuration leads, as a result of scalar-scalar interaction, to a new hypothetical "mass" that confines test scalar charges in bound orbits, but does not interact with neutral test particles.Comment: 18 page

Dynamical spin correlations in Heisenberg ladder under magnetic field and correlation functions in SO(5) ladder

The zero-temperature dynamical spin-spin correlation functions are calculated for the spin-1/2 two-leg Heisenberg ladder in a magnetic field above the lower critical field Hc1. The dynamical structure factors are calculated which exhibit both massless and massive excitations. These modes appear in different sectors characterized by the parity in the rung direction and by the momentum in the direction of the chains. The structure factors have power-law singularities at the lower edges of their support. The results are also applicable to spin-1 Heisenberg chain. The implications are briefly discussed for various correlation functions and the pi-resonance in the SO(5) symmetric ladder model.Comment: 15 pages, 6 figures, added references; final version to appear in Phys. Rev.

Automatically refining partial specifications for Program Verification

10.1007/978-3-642-21437-0_28Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)6664 LNCS369-38