Analytical prediction of labyrinth-seal-flow-induced arotor excitation forces

An analytical method to calculate the rotor excitation forces arising from labyrinth seals is presented. The objective is to model the gas flow through the seal clearance passages and cavities when the rotor is positioned eccentricly relative to the stator center. The seal flow model used in the analysis yields solutions which validate the experimentally observed influence of seal parameters on seal forces reported in the literature. The analytically predicted seal pressure distributions and forces were compared with published experimental results

MR Spectroscopic Imaging of Peripheral Zone in Prostate Cancer Using a 3T MRI Scanner: Endorectal versus External Phased Array Coils.

Magnetic resonance spectroscopic imaging (MRSI) detects alterations in major prostate metabolites, such as citrate (Cit), creatine (Cr), and choline (Ch). We evaluated the sensitivity and accuracy of three-dimensional MRSI of prostate using an endorectal compared to an external phased array "receive" coil on a 3T MRI scanner. Eighteen patients with prostate cancer (PCa) who underwent endorectal MR imaging and proton (1H) MRSI were included in this study. Immediately after the endorectal MRSI scan, the PCa patients were scanned with the external phased array coil. The endorectal coil-detected metabolite ratio [(Ch+Cr)/Cit] was significantly higher in cancer locations (1.667 ± 0.663) compared to non-cancer locations (0.978 ± 0.420) (P < 0.001). Similarly, for the external phased array, the ratio was significantly higher in cancer locations (1.070 ± 0.525) compared to non-cancer locations (0.521 ± 0.310) (P < 0.001). The sensitivity and accuracy of cancer detection were 81% and 78% using the endorectal 'receive' coil, and 69% and 75%, respectively using the external phased array 'receive' coil

Performance improvement of piezoelectric materials in energy harvesting in recent days – a review

Piezoelectric elements are inevitable in modern day physics playing a vital role in many applications. Any piezoelectric element requires compression to produce energy in the form of a weak electrical ac signal. Mechanical vibrations are known to cause deflections which are enough to produce energy from the piezoelectric materials. In this paper, a review of the piezoelectric materials is made on their basic modes of excitation for producing energy. Also, various mechanisms and techniques used to harvest energy recently are presented and discussed extensively. Piezoelectric energy harvesting using MEMS is emphasized much as this is the era of micromechanical systems. Most of the piezoelectric energy harvesting systems relies on cantilever-oriented deflection to produce maximum vibration. In general cantilever beams fitted with piezoelectric materials produce electrical energy from mechanical vibration when deflected; hence detailed review on the different shapes of cantilever is also submitted. Significant parameters contributing to improved performance are dealt with special importance

Investigation into the security and privacy of iOS VPN applications

Due to the increasing number of recommendations for people to use Virtual Private Networks (VPNs) to protect their privacy, more application developers are creating VPN applications and publishing them on the Apple App Store and Google Play Store. In this ‘gold rush’, applications are being developed quickly and, in turn, not being developed with security in mind.This paper investigated a selection of VPN applications available on the Apple App Store (for iOS devices) and tested the applications for security and privacy issues. This includes testing for any traffic being transmitted over plain HTTP, DNS leakage and transmission of personally identifiable information (such as phone number, International Mobile Equipment Identity (IMEI), email address, MAC address) and evaluating the security of the tunneling protocol used by the VPN.The testing methodology involved installing VPN applications on a test device, simulating network traffic for a pre-defined period of time and capturing the traffic. This allows for all traffic to be analysed to check for anything being sent without encryption. Other issues that often cause de-anonymization with VPN applications such as DNS leakage were also considered.The research found several common security issues with VPN applications tested, with a large majority of applications still using HTTP and not HTTPS for transmitting certain data. A large majority of the VPN applications failed to route additional user data (such as DNS queries) through the VPN tunnel. Furthermore, just fifteen of the tested applications were found to have correctly implemented the best-recommended tunneling protocol for user security.Outside of the regular testing criteria, other security anomalies were observed with specific applications, which included outdated servers with known vulnerabilities, applications giving themselves the ability to perform HTTPS interception and questionable privacy policies. From the documented vulnerabilities, this research proposes a set of recommendations for developers to consider when developing VPN applications

Simulation of the Performance of the IISc Chemical Kinetics Shock Tube

This report presents the results of an investigation of the performance of the Chemical Kinetics Shock tube at the Indian Institute of Science. The one-dimensional Lagrangian code L1d of Jacobs (1998) has been used to simulate the tube at several operating conditions. The conditions have different shock tube filling pressures, resulting in different shock speeds and different tube lengths, resulting in different dwell times. The simulations have been performed both with and without viscous effects simulated in the tubes. At the lowest shock tube filling pressure condition, the shock tube operates in an overtailored mode and it is undertailored at the higher filling pressure conditions. The results show that viscous effects, which lead to attenuation of the primary shock and heat loss from the test gas to the tube walls, result in an increasing p5 pressure during the test time. The viscous effects are more dominant at the condition with the lowest filling pressure (highest primary shock speed). A simulation run for 50 ms after diaphragm rupture or the configuration with a long driver tube shows that the test gas is periodically re-compressed by reflections of waves along the driver and shock tubes. The recompressions become sequentially weaker and thus the test gas temperature and pressure are never raised to as high levels as for the primary compression

Therapeutic DNA vaccine induces broad T cell responses in the gut and sustained protection from viral rebound and AIDS in SIV-infected rhesus macaques.

Immunotherapies that induce durable immune control of chronic HIV infection may eliminate the need for life-long dependence on drugs. We investigated a DNA vaccine formulated with a novel genetic adjuvant that stimulates immune responses in the blood and gut for the ability to improve therapy in rhesus macaques chronically infected with SIV. Using the SIV-macaque model for AIDS, we show that epidermal co-delivery of plasmids expressing SIV Gag, RT, Nef and Env, and the mucosal adjuvant, heat-labile E. coli enterotoxin (LT), during antiretroviral therapy (ART) induced a substantial 2-4-log fold reduction in mean virus burden in both the gut and blood when compared to unvaccinated controls and provided durable protection from viral rebound and disease progression after the drug was discontinued. This effect was associated with significant increases in IFN-γ T cell responses in both the blood and gut and SIV-specific CD8+ T cells with dual TNF-α and cytolytic effector functions in the blood. Importantly, a broader specificity in the T cell response seen in the gut, but not the blood, significantly correlated with a reduction in virus production in mucosal tissues and a lower virus burden in plasma. We conclude that immunizing with vaccines that induce immune responses in mucosal gut tissue could reduce residual viral reservoirs during drug therapy and improve long-term treatment of HIV infection in humans

Accelerated echo planar J

Overlap of metabolites is a major limitation in one-dimensional (1D) spectral-based single voxel MR Spectroscopy (MRS) and multivoxel-based MR spectroscopic imaging (MRSI). By combining echo-planar spectroscopic imaging (EPSI) with two-dimensional (2D) J resolved spectroscopic sequence (JPRESS), 2D spectra can be recorded in multiple locations in a single slice of prostate using four dimensional (4D) Echo-Planar J-Resolved Spectroscopic Imaging (EP-JRESI). The goal of the present work was to validate two different non-linear reconstruction methods independently using compressed sensing based 4D EP-JRESI in Prostate Cancer (PCa): Maximum Entropy (MaxEnt) and Total Variation (TV). Twenty two prostate cancer patients with a mean age of 63.8 years (range: 46–79 years) were investigated in this study. A 4D non-uniformly under-sampled (NUS) EP-JRESI sequence was implemented on the Siemens 3T MRI scanner. The NUS data was reconstructed using two non-linear reconstruction methods, namely MaxEnt and TV. Using both TV and MaxEnt reconstruction methods, following observations were made in cancer compared to non-cancerous locations: 1) higher mean (Ch+Cr)/Cit metabolite ratios. 2) Increased levels of (Ch+Cr)/Spm, (Ch+Cr)/mI and decreased levels of (Ch+Cr)/Glx. We have shown that it is possible to accelerate the 4D EP-JRESI sequence by 4X and that the data can be reliably reconstructed using the TV and MaxEnt methods. The total acquisition duration was less than 13 minutes and we were able to detect and quantify several metabolites

Individual participant data (IPD)-level meta-analysis of randomised controlled trials to estimate the vitamin D dietary requirements in dark-skinned individuals resident at high latitude

Context and purpose There is an urgent need to develop vitamin D dietary recommendations for dark-skinned populations resident at high latitude. Using data from randomised controlled trials (RCTs) with vitamin D3-supplements/fortified foods, we undertook an individual participant data-level meta-regression (IPD) analysis of the response of wintertime serum 25-hydroxyvitamin (25(OH)D) to total vitamin D intake among dark-skinned children and adults residing at ≥ 40° N and derived dietary requirement values for vitamin D. Methods IPD analysis using data from 677 dark-skinned participants (of Black or South Asian descent; ages 5–86 years) in 10 RCTs with vitamin D supplements/fortified foods identified via a systematic review and predefined eligibility criteria. Outcome measures were vitamin D intake estimates across a range of 25(OH)D thresholds. Results To maintain serum 25(OH)D concentrations ≥ 25 and 30 nmol/L in 97.5% of individuals, 23.9 and 27.3 µg/day of vitamin D, respectively, were required among South Asian and 24.1 and 33.2 µg/day, respectively, among Black participants. Overall, our age-stratified intake estimates did not exceed age-specific Tolerable Upper Intake Levels for vitamin D. The vitamin D intake required by dark-skinned individuals to maintain 97.5% of winter 25(OH)D concentrations ≥ 50 nmol/L was 66.8 µg/day. This intake predicted that the upper 2.5% of individuals could potentially achieve serum 25(OH)D concentrations ≥ 158 nmol/L, which has been linked to potential adverse effects in older adults in supplementation studies. Conclusions Our IPD-derived vitamin D intakes required to maintain 97.5% of winter 25(OH)D concentrations ≥ 25, 30 and 50 nmol/L are substantially higher than the equivalent estimates for White individuals. These requirement estimates are also higher than those currently recommended internationally by several agencies, which are based predominantly on data from Whites and derived from standard meta-regression based on aggregate data. Much more work is needed in dark-skinned populations both in the dose–response relationship and risk characterisation for health outcomes.Peer reviewe

Widespread DNA hypomethylation at gene enhancer regions in placentas associated with early-onset pre-eclampsia.

Pre-eclampsia is a serious complication of pregnancy that can affect both maternal and fetal outcomes. Early-onset pre-eclampsia (EOPET) is a severe form of pre-eclampsia that is associated with altered physiological characteristics and gene expression in the placenta. DNA methylation is a relatively stable epigenetic modification to DNA that can reflect gene expression, and can provide insight into the mechanisms underlying such expression changes. This case-control study focused on DNA methylation and gene expression of whole chorionic villi samples from 20 EOPET placentas and 20 gestational age-matched controls from pre-term births. DNA methylation was also assessed in placentas affected by late-onset pre-eclampsia (LOPET) and normotensive intrauterine growth restriction (nIUGR). The Illumina HumanMethylation450 BeadChip was used to assess DNA methylation at >480 000 cytosine-guanine dinucleotide (CpG) sites. The Illumina HT-12v4 Expression BeadChip was used to assess gene expression of >45 000 transcripts in a subset of cases and controls. DNA methylation analysis by pyrosequencing was used to follow-up the initial findings in four genes with a larger cohort of cases and controls, including nIUGR and LOPET placentas. Bioinformatic analysis was used to identify overrepresentation of gene ontology categories and transcription factor binding motifs. We identified 38 840 CpG sites with significant (false discovery rate 12.5% methylation difference compared with the controls. Significant sites were enriched at the enhancers and low CpG density regions of the associated genes and the majority (74.5%) of these sites were hypomethylated in EOPET. EOPET, but not associated clinical features, such as intrauterine growth restriction (IUGR), presented a distinct DNA methylation profile. CpG sites from four genes relevant to pre-eclampsia (INHBA, BHLHE40, SLC2A1 and ADAM12) showed different extent of changes in LOPET and nIUGR. Genome-wide expression in a subset of samples showed that some of the gene expression changes were negatively correlated with DNA methylation changes, particularly for genes that are responsible for angiogenesis (such as EPAS1 and FLT1). Results could be confounded by altered cell populations in abnormal placentas. Larger sample sizes are needed to fully address the possibility of sub-profiles of methylation within the EOPET cohort. Based on DNA methylation profiling, we conclude that there are widespread DNA methylation alterations in EOPET that may be associated with changes in placental function. This property may provide a useful tool for early screening of such placentas. This study identifies DNA methylation changes at many loci previously reported to have altered gene expression in EOPET placentas, as well as in novel biologically relevant genes we confirmed to be differentially expressed. These results may be useful for DNA- methylation-based non-invasive prenatal diagnosis of at-risk pregnancies

Synthesis of macrocyclic receptors with intrinsic fluorescence featuring quinizarin moieties

An unprecedented class of macrocycles with intrinsic fluorescence consisting of phenolic trimers and quinizarin is developed. Though they are lacking strong hydrogen bonds as observed in calixarenes, the two examples introduced here each adopt a vase-like conformation with all four aromatic units pointing in one direction (syn orientation). This “cone” conformation has been confirmed by NMR spectroscopy, molecular modeling, and X-ray crystallography. The laminar, electron-rich fluorophore as part of the macrocycle allows additional contacts to enclosed guest molecules