Scalable and accurate causality tracking for eventually consistent stores

Lecture Notes in Computer Science 8460, 2014In cloud computing environments, data storage systems often rely on optimistic replication to provide good performance and availability even in the presence of failures or network partitions. In this scenario, it is important to be able to accurately and efficiently identify updates executed concurrently. Current approaches to causality tracking in optimistic replication have problems with concurrent updates: they either (1) do not scale, as they require replicas to maintain information that grows linearly with the number of writes or unique clients; (2) lose information about causality, either by removing entries from client-id based version vectors or using server-id based version vectors, which cause false conflicts. We propose a new logical clock mechanism and a logical clock framework that together support a traditional key-value store API, while capturing causality in an accurate and scalable way, avoiding false conflicts. It maintains concise information per data replica, only linear on the number of replica servers, and allows data replicas to be compared and merged linear with the number of replica servers and versions.(undefined

The 2-Channel Kondo Model I: Review of Experimental Evidence for its Realization in Metal Nanoconstrictions

Certain zero-bias anomalies (ZBAs) in the voltage, temperature and magnetic field dependence of the conductance $G(V,T,H)$ of quenched Cu point contacts have previously been interpreted to be due to non-magnetic 2-channel Kondo (2CK) scattering from near-degenerate atomic two-level tunneling systems (Ralph and Buhrman, 1992; Ralph et al. 1994), and hence to represent an experimental realization of the non-Fermi-liquid physics of the T=0 fixed point of the 2-channel Kondo model. In this, the first in a series of three papers (I,II,III) devoted to 2-channel Kondo physics, we present a comprehensive review of the quenched Cu ZBA experiments and their 2CK interpretation, including new results on ZBAs in constrictions made from Ti or from metallic glasses. We first review the evidence that the ZBAs are due to electron scattering from stuctural defects that are not static, but possess internal dynamics. In order to distinguish between several mechanisms proposed to explain the experiments, we then analyze the scaling properties of the conductance at low temperature and voltage and extract from the data a universal scaling function $\Gamma(v)$. The theoretical calculation of the corresponding scaling function within the 2CK model is the subject of papers II and III. The main conclusion of our work is that the properties of the ZBAs, and most notably their scaling behavior, are in good agreement with the 2CK model and clearly different from several other proposed mechanisms.Comment: 35 pages RevTeX, 19 encapsulated postscript figures; this final published version features two additional authors, an additional section reviewing recent experiments on Ti nanoconstrictions that agree very well with the 2-channel Kondo model, 6 new figures (and is much shorter the previous 53 page version, due to reformatting

Whole-genome sequencing reveals host factors underlying critical COVID-19

Critical COVID-19 is caused by immune-mediated inflammatory lung injury. Host genetic variation influences the development of illness requiring critical care1 or hospitalization2,3,4 after infection with SARS-CoV-2. The GenOMICC (Genetics of Mortality in Critical Care) study enables the comparison of genomes from individuals who are critically ill with those of population controls to find underlying disease mechanisms. Here we use whole-genome sequencing in 7,491 critically ill individuals compared with 48,400 controls to discover and replicate 23 independent variants that significantly predispose to critical COVID-19. We identify 16 new independent associations, including variants within genes that are involved in interferon signalling (IL10RB and PLSCR1), leucocyte differentiation (BCL11A) and blood-type antigen secretor status (FUT2). Using transcriptome-wide association and colocalization to infer the effect of gene expression on disease severity, we find evidence that implicates multiple genes—including reduced expression of a membrane flippase (ATP11A), and increased expression of a mucin (MUC1)—in critical disease. Mendelian randomization provides evidence in support of causal roles for myeloid cell adhesion molecules (SELE, ICAM5 and CD209) and the coagulation factor F8, all of which are potentially druggable targets. Our results are broadly consistent with a multi-component model of COVID-19 pathophysiology, in which at least two distinct mechanisms can predispose to life-threatening disease: failure to control viral replication; or an enhanced tendency towards pulmonary inflammation and intravascular coagulation. We show that comparison between cases of critical illness and population controls is highly efficient for the detection of therapeutically relevant mechanisms of disease

Lung density measurements in spontaneous pneumathorax demonstrate air trapping.

PURPOSE: Idiopathic spontaneous pneumothorax (SP) is the result of leakage of air from the lung parenchyma through a ruptured visceral pleura into the pleural cavity. This rupture is thought to be caused by an increased pressure difference between parenchymal airspace and pleural cavity. We hypothesize that rather peripheral airway inflammation leads to obstruction with check valve phenomena and by that to airtrapping in the lung parenchyma, which precedes spontaneous pneumothorax. SETTING: University hospital. MATERIALS AND METHODS: Forty-one matched healthy volunteers (21 smokers and 20 nonsmokers), and 41 patients with SP (21 patients with and 20 patients without bullae) underwent spirometrically controlled high-resolution CT density measurements with automatic contour tracing at 10% and at 90% of vital capacity. RESULTS: Patients with SP showed lower mean lung density (MLD) values and higher percentages of Hounsfield units (HU) below - 900 HU (pixel index [PI]) compared to the healthy volunteers on expiratory scans. This enhanced airtrapping phenomenon is seen in both the SP lung (MLD, p = 002; PI, p = 0.01) and the contralateral lung (MLD, p = 0.009; PI, p = 0.05) compared to the control subjects. The difference with control subjects is independent of smoking behavior and bullae. CONCLUSIONS: Peripheral airway obstruction with airtrapping was found, and it is supposed to play an important role in the pathogenesis of spontaneous pneumothorax. (aut. ref.

Lung attenuation measurements in healthy young adults.

Background: High-resolution computed tomography (HRCT) attenuation measurements may be more sensitive in finding early emphysematous changes in relatively young subjects than lung function measurements. Objectives: To define lung attenuation parameters in smokers and never-smokers. Methods: A prospective comparative study in a university hospital setting was designed with 20 healthy smoking and 20 nonsmoking volunteers. Attenuation measurements on spirometrically controlled HRCT at three levels in the upper half of the lungs at 10% and 90% of vital capacity (VC10% and VD90%) were done, and lung function measurements were performed. Results: Mean lung attenuation (MLD) and pixel index (PI) were correlated with lung function and smoking history. Small attenuation differences in the left and right lung were found but no sex-related differences. At main carina (MC) level, the PI was higher at VC90% (p < 0.0001) but lower at VC10% (p < 0.01) compared to the apex. Age correlated with attenuation parameters at VC10%, whereas for pack-years no correlation was found. There were attenuation correlations with VC (PI: R = 0.31, p < 0.05 at VC10%/90%), residual volume (MLD: R = -0.31, p < 0.05 at VC10%), and total lung capacity (PI: R = 0.31, p < 0.05 at VC10%/VC90%). Conclusions: Lung attenuation during inspiration was lower at the MC level than at the top, but higher on expiratory scans. No sex-related differences were found. Lung attenuation decreases with age on expiratory scans. This seemed to be of more importance than the amount of pack-years of smoking. A relationship with lung function parameters is not uniformly proven. (aut. ref.

Lung attenuation measurements in healthy young adults.

0.05 at VC10%/VC90%). CONCLUSIONS: Lung attenuation during inspiration was lower at the MC level than at the top, but higher on expiratory scans. No sex-related differences were found. Lung attenuation decreases with age on expiratory scans. This seemed to be of more importance than the amount of pack-years of smoking. A relationship with lung function parameters is not uniformly proven

The ergonomics of the maintenance of mining equipment (including ergonomic principles in designing for maintainability)

SIGLEAvailable from British Library Document Supply Centre- DSC:7521.33(IOM-TM--85/12) / BLDSC - British Library Document Supply CentreGBUnited Kingdo