Better Performance Through Thread-local Emulation

ABSTRACT Mobile platforms are shifting away from managed code and toward native code. For example, the most recent versions of Android compile Dalvik bytecodes to native code at installtime, and apps frequently use third-party native libraries. The trend toward native code on mobile platforms calls us to develop new ways of building dynamic taint-tracking tools, such as TaintDroid, that achieve good performance. In this paper, we argue that the key to good performance is to track only when necessary, e.g., when an app handles sensitive data. We argue that thread-local emulation is a feature that captures this goal. In this paper, we discuss the motivation for thread-local emulation, the software and hardware techniques that may be used to implement it, results from preliminary work, and the many challenges that remain

Spandex: Secure password tracking for android

Abstract This paper presents SpanDex, a set of extensions to Android's Dalvik virtual machine that ensures apps do not leak users' passwords. The primary technical challenge addressed by SpanDex is precise, sound, and efficient handling of implicit information flows (e.g., information transferred by a program's control flow). SpanDex handles implicit flows by borrowing techniques from symbolic execution to precisely quantify the amount of information a process' control flow reveals about a secret. To apply these techniques at runtime without sacrificing performance, SpanDex runs untrusted code in a data-flow sensitive sandbox, which limits the mix of operations that an app can perform on sensitive data. Experiments with a SpanDex prototype using 50 popular Android apps and an analysis of a large list of leaked passwords predicts that for 90% of users, an attacker would need over 80 login attempts to guess their password. Today the same attacker would need only one attempt for all users

Effectiveness of a national quality improvement programme to improve survival after emergency abdominal surgery (EPOCH): a stepped-wedge cluster-randomised trial

Background: Emergency abdominal surgery is associated with poor patient outcomes. We studied the effectiveness of a national quality improvement (QI) programme to implement a care pathway to improve survival for these patients. Methods: We did a stepped-wedge cluster-randomised trial of patients aged 40 years or older undergoing emergency open major abdominal surgery. Eligible UK National Health Service (NHS) hospitals (those that had an emergency general surgical service, a substantial volume of emergency abdominal surgery cases, and contributed data to the National Emergency Laparotomy Audit) were organised into 15 geographical clusters and commenced the QI programme in a random order, based on a computer-generated random sequence, over an 85-week period with one geographical cluster commencing the intervention every 5 weeks from the second to the 16th time period. Patients were masked to the study group, but it was not possible to mask hospital staff or investigators. The primary outcome measure was mortality within 90 days of surgery. Analyses were done on an intention-to-treat basis. This study is registered with the ISRCTN registry, number ISRCTN80682973. Findings: Treatment took place between March 3, 2014, and Oct 19, 2015. 22 754 patients were assessed for elegibility. Of 15 873 eligible patients from 93 NHS hospitals, primary outcome data were analysed for 8482 patients in the usual care group and 7374 in the QI group. Eight patients in the usual care group and nine patients in the QI group were not included in the analysis because of missing primary outcome data. The primary outcome of 90-day mortality occurred in 1210 (16%) patients in the QI group compared with 1393 (16%) patients in the usual care group (HR 1·11, 0·96–1·28). Interpretation: No survival benefit was observed from this QI programme to implement a care pathway for patients undergoing emergency abdominal surgery. Future QI programmes should ensure that teams have both the time and resources needed to improve patient care. Funding: National Institute for Health Research Health Services and Delivery Research Programme

Effectiveness of a national quality improvement programme to improve survival after emergency abdominal surgery (EPOCH): a stepped-wedge cluster-randomised trial

BACKGROUND: Emergency abdominal surgery is associated with poor patient outcomes. We studied the effectiveness of a national quality improvement (QI) programme to implement a care pathway to improve survival for these patients. METHODS: We did a stepped-wedge cluster-randomised trial of patients aged 40 years or older undergoing emergency open major abdominal surgery. Eligible UK National Health Service (NHS) hospitals (those that had an emergency general surgical service, a substantial volume of emergency abdominal surgery cases, and contributed data to the National Emergency Laparotomy Audit) were organised into 15 geographical clusters and commenced the QI programme in a random order, based on a computer-generated random sequence, over an 85-week period with one geographical cluster commencing the intervention every 5 weeks from the second to the 16th time period. Patients were masked to the study group, but it was not possible to mask hospital staff or investigators. The primary outcome measure was mortality within 90 days of surgery. Analyses were done on an intention-to-treat basis. This study is registered with the ISRCTN registry, number ISRCTN80682973. FINDINGS: Treatment took place between March 3, 2014, and Oct 19, 2015. 22 754 patients were assessed for elegibility. Of 15 873 eligible patients from 93 NHS hospitals, primary outcome data were analysed for 8482 patients in the usual care group and 7374 in the QI group. Eight patients in the usual care group and nine patients in the QI group were not included in the analysis because of missing primary outcome data. The primary outcome of 90-day mortality occurred in 1210 (16%) patients in the QI group compared with 1393 (16%) patients in the usual care group (HR 1·11, 0·96-1·28). INTERPRETATION: No survival benefit was observed from this QI programme to implement a care pathway for patients undergoing emergency abdominal surgery. Future QI programmes should ensure that teams have both the time and resources needed to improve patient care. FUNDING: National Institute for Health Research Health Services and Delivery Research Programme

Hypernatraemia in South African hospitalized patients

CITATION: Abohajir, A., Rensburg, M. A. & Davids, M. R. 2019. Hypernatraemia in South African hospitalized patients. African Journal of Nephrology, 22(1):12-16, doi:10.21804/22-1-3285.The original publication is available at http://www.journals.ac.za/index.php/ajn/Background: Hypernatraemia is a common electrolyte problem in hospitalized patients and is associated with a high mortality rate. We determined the incidence, causes, management, and outcomes of hypernatraemia in adult hospitalized patients at a large South African tertiary hospital. Methods: A retrospective study was conducted at Tygerberg Hospital in Cape Town, South Africa. Adult patients with hypernatraemia (at least one serum sodium concentration ≥150 mmol/L) during a 3-month period in 2014 were identified from our laboratory database for inclusion. Results: There were 204 patients with hypernatraemia, a prevalence of 1.5%. Of these patients, 101 (49.5%) were male, and the mean age was 53 years. There were 66 patients (32.4%) who had hypernatraemia on admission, and 138 who developed it during the course of their stay in hospital. The overall in-hospital mortality was 38.7%, with higher rates for older patients and those with more severe degrees of hypernatraemia. Contributory causes which were most commonly present included dehydration/hypovolaemia (45%), followed by sepsis (39%). Net sodium gain, rather than water deficit, was identified as the main mechanism in most of the patients who developed hypernatraemia in the intensive care units. We found little evidence of any diagnostic work-up and also found that the details of fluid therapy and intake–output charting were poorly documented. Conclusions: There is a very high mortality rate in our hospitalized patients with hypernatraemia. The diagnostic work-up and therapy were often inadequate or poorly documented. The management of this important condition needs to be improved with the aid of standardized protocols.http://www.journals.ac.za/index.php/ajn/article/view/3285Publisher's versio

Effect of poling on the dielectric properties of synthesized β-poly (vinylidene fluoride) foam

A straightforward scalable method for synthesizing β-poly (vinylidene fluoride) polymer foam from a sugar template has been used. A characteristic β-phase of the foam was confirmed by infrared and micro-Raman spectroscopy with significant enhancement observed after poling. The electrical polarization of the foam revealed a ferroelectric nature with dielectric strength higher than 30 kV/cm which is close to the commercial value. Poled samples had a dielectric constant of 5.5, higher than the value of the unpoled sample (3.05). These values appear stable over the low-frequency range from 1 kHz to 1 MHz. Significant reverse behavior was observed at higher frequencies from 300 GHz to 3 THz frequencies. It was found that the open-cell foam with a porosity of 88% has the lowest dielectric constant value (1.07 at 1.8 THz, reaching 1.04 at 2.9 THz) compared to the foam with 20% porosity (2.17 at 1 THz, reaching 1.83 at 3 THz). Furthermore, the Maxwell Garnett model, in conjunction with THz imaging, confirmed the impact of porosity on dielectric properties. These findings pave the way for the efficient fabrication of ferroelectric porous polymer structures that can be used in dielectric switching at the kHz-THz frequency range.Published versio

Corporate aggregate disclosure practices in Jordan

This study reports the results of an empirical investigation of the disclosure behavior of listed companies in Jordan after important changes in economic and accounting regulations. It also reports the relationship between aggregate disclosure (both mandatory and voluntary) and a number of company characteristics (financial and non-financial) for Jordanian companies listed in Amman Stock Exchange (ASE). The results of the study revealed that there was a significant increase in the level of aggregate disclosure (its average was 69%) compared to previous studies in Jordan. The extent of mandatory and voluntary disclosures was 83% and 34% respectively. Univariate analysis revealed that firm size, profitability, number of shareholders, listing status, industry type, audit firm size and company age are significant variables in explaining the variation in the level of aggregate disclosure among Jordanian companies. Meanwhile, multivariate analysis showed firm size (sales), profitability (ROE), audit firm size, industry type and listing status, to be significantly associated with the level of aggregate disclosure