Learning a Static Analyzer from Data

To be practically useful, modern static analyzers must precisely model the effect of both, statements in the programming language as well as frameworks used by the program under analysis. While important, manually addressing these challenges is difficult for at least two reasons: (i) the effects on the overall analysis can be non-trivial, and (ii) as the size and complexity of modern libraries increase, so is the number of cases the analysis must handle. In this paper we present a new, automated approach for creating static analyzers: instead of manually providing the various inference rules of the analyzer, the key idea is to learn these rules from a dataset of programs. Our method consists of two ingredients: (i) a synthesis algorithm capable of learning a candidate analyzer from a given dataset, and (ii) a counter-example guided learning procedure which generates new programs beyond those in the initial dataset, critical for discovering corner cases and ensuring the learned analysis generalizes to unseen programs. We implemented and instantiated our approach to the task of learning JavaScript static analysis rules for a subset of points-to analysis and for allocation sites analysis. These are challenging yet important problems that have received significant research attention. We show that our approach is effective: our system automatically discovered practical and useful inference rules for many cases that are tricky to manually identify and are missed by state-of-the-art, manually tuned analyzers

Bioactive composites for bone tissue engineering

One of the major challenges of bone tissue engineering is the production of a suitable scaffold material. In this review the current composite materials options available are considered covering both the methods of both production and assessing the scaffolds. A range of production routes have been investigated ranging from the use of porogens to produce the porosity through to controlled deposition methods. The testing regimes have included mechanical testing of the materials produced through to in vivo testing of the scaffolds. While the ideal scaffold material has not yet been produced, progress is being made

Life Insurance Consumption as a Function of Wealth Change

This article used a large nationally representative longitudinal dataset to explore the association between changing socioeconomic factors and household consumption of life insurance across time. This study specifically examined the association between changes in wealth and life insurance consumption controlling for household characteristics and psychosocial factors. Empirical results indicate that during the 2004-2008 period, an increase in net worth was positively associated with purchases of additional cash value life insurance at the household level. Women and Black households were also more likely to increase their life insurance consumption during this period. Saving intention was likewise found to be positively associated with an increase in household life insurance consumption. Results suggest that life insurance acts a complement to, rather than substitute for, wealth. Implications of the findings of this study for individual investors, scholars and practitioners have been included

Cloning and Functional Analysis of three Cold Regulated <em>CBF</em> Genes in the Overwintering Crucifer <em>Boechera stricta</em>

In this research, we isolated three CBF (C-repeat-Binding Factors) genes from two genotypes of Boechera stricta with contrasting freezing tolerance and characterized their structure and expression patterns in response to cold treatment. An amino acid sequence comparison revealed that the CBF genes in B. stricta showed high conservation in the AP2 domain and PKKP/RAGR motif like other cold adaptable Brassicaceae. The pairwise sequence alignment of the CBF genes isolated from two genotypes of B. stricta showed non-synonymous mutations in CBF 2 and 3. Gene expression analysis demonstrated that CBF genes in B. stricta have expression patterns similar to CBFs in A. thaliana in response to cold treatment, while differential expression at the molecular level in CBF and COR genes was presented between two genotypes of B. stricta. Our results suggest that signal transduction of three CBF genes can be one of the central pathways in the development of freezing tolerance in B. stricta

Adenosine-induced ST segment depression with normal perfusion

Background: Intravenous adenosine in conjunction with myocardial perfusion imaging is commonly used for the detection of coronary artery disease and risk assessment. We have previously shown that patients with ischemic changes on the 12-lead electrocardiogram (ECG) in response to adenosine but with normal perfusion pattern have a benign outcome on shortintermediate follow-up. The long-term outcome of these patients is unknown. Methods: Patients with ischemic ECG response (&#8805; 1 mm ST depression) to adenosine infusion but with normal perfusion on single-photon emission computed tomography (SPECT) imaging in the absence of a history of myocardial infarction or coronary revascularization were followed up for mortality, myocardial infarctions, and coronary revascularization. Results: The cohort consisted of 73 patients (81% women) who were followed up for mortality for a mean of 61 &#177; 15 months. There were 10 deaths, and the cause of death was determined to be non-cardiac in half of those. Follow-up for the other endpoints was complete for 21 &#177; 10 months during which no patient had myocardial infarction and seven underwent coronary revascularization. Conclusions: Patients with ischemic ECG response to intravenous adenosine administration and normal perfusion on SPECT are at low risk of cardiovascular events. The ST segment response to adenosine in this setting is likely related to non-ischemic mechanisms

Magnetic interactions in transition metal doped ZnO : An abinitio study

We calculate the nature of magnetic interactions in transition-metal doped ZnO using the local spin density approximation and LSDA+\textit{U} method of density functional theory. We investigate the following four cases: (i) single transition metal ion types (Cr, Mn, Fe, Co, Ni and Cu) substituted at Zn sites, (ii) substitutional magnetic transition metal ions combined with additional Cu and Li dopants, (iii) substitutional magnetic transition metal ions combined with oxygen vacancies and (iv) pairs of magnetic ion types (Co and Fe, Co and Mn, etc.). Extensive convergence tests indicate that the calculated magnetic ground state is unusually sensitive to the k-point mesh and energy cut-off, the details of the geometry optimizations and the choice of the exchange-correlation functional. We find that ferromagnetic coupling is sometimes favorable for single type substitutional transition metal ions within the local spin density approximation. However, the nature of magnetic interactions changes when correlations on the transition-metal ion are treated within the more realistic LSDA + \textit{U} method, often disfavoring the ferromagnetic state. The magnetic configuration is sensitive to the detailed arrangement of the ions and the amount of lattice relaxation, except in the case of oxygen vacancies when an antiferromagnetic state is always favored.Comment: 11 pages, 17 figure

Z_3 Strings and their Interactions

We construct Z_3 vortex solutions in a model in which SU(3) is spontaneously broken to Z_3. The model is truncated to one in which there are only two dimensionless free parameters and the interaction of vortices within this restricted set of models is studied numerically. We find that there is a curve in the two dimensional space of parameters for which the energy of two asymptotically separated vortices equals the energy of the vortices at vanishing separation. This suggests that the inter-vortex potential for Z_3 strings might be flat for these couplings, much like the case of U(1) strings in the Bogomolnyi limit. However, we argue that the intervortex potential is attractive at short distances and repulsive at large separations leading to the possibility of unstable bound states of Z_3 vortices.Comment: 8 pages; mainly corrected typos in table

Effect of biochars pyrolyzed in N2 and CO2, and feedstock on microbial community in metal(loid)s contaminated soils

Little is known about the effects of applying amendments on soil for immobilizing metal(loid)s on the soil microbial community. Alterations in the microbial community were examined after incubation of treated contaminated soils. One soil was contaminated with Pb and As, a second soil with Cd and Zn. Red pepper stalk (RPS) and biochars produced from RPS in either N2 atmosphere (RPSN) or CO2 atmosphere (RPSC) were applied at a rate of 2.5% to the two soils and incubated for 30 days. Bacterial communities of control and treated soils were characterized by sequencing 16S rRNA genes using the Illumina MiSeq sequencing. In both soils, bacterial richness increased in the amended soils, though somewhat differently between the treatments. Evenness values decreased significantly, and the final overall diversities were reduced. The neutralization of pH, reduced available concentrations of Pb or Cd, and supplementation of available carbon and surface area could be possible factors affecting the community changes. Biochar amendments caused the soil bacterial communities to become more similar than those in the not amended soils. The bacterial community structures at the phylum and genus levels showed that amendment addition might restore the normal bacterial community of soils, and cause soil bacterial communities in contaminated soils to normalize and stabilize

Spontaneous Symmetry Breaking of Population between Two Dynamic Attractors in a Driven Atomic Trap: Ising-class Phase Transition

We have observed spontaneous symmetry breaking of atomic populations in the dynamic phase-space double-potential system, which is produced in the parametrically driven magneto-optical trap of atoms. We find that the system exhibits similar characteristics of the Ising-class phase transition and the critical value of the control parameter, which is the total atomic number, can be calculated. In particular, the collective effect of the laser shadow becomes dominant at large atomic number, which is responsible for the population asymmetry of the dynamic two-state system. This study may be useful for investigation of dynamic phase transition and temporal behaviour of critical phenomena.Comment: 4 pages, 4 figure