Fiber optic reference frequency distribution to remote beam waveguide antennas

In the NASA/JPL Deep Space Network (DSN), radio science experiments (probing outer planet atmospheres, rings, gravitational waves, etc.) and very long-base interferometry (VLBI) require ultra-stable, low phase noise reference frequency signals at the user locations. Typical locations for radio science/VLBI exciters and down-converters are the cone areas of the 34 m high efficiency antennas or the 70 m antennas, located several hundred meters from the reference frequency standards. Over the past three years, fiber optic distribution links have replaced coaxial cable distribution for reference frequencies to these antenna sites. Optical fibers are the preferred medium for distribution because of their low attenuation, immunity to EMI/IWI, and temperature stability. A new network of Beam Waveguide (BWG) antennas presently under construction in the DSN requires hydrogen maser stability at tens of kilometers distance from the frequency standards central location. The topic of this paper is the design and implementation of an optical fiber distribution link which provides ultra-stable reference frequencies to users at a remote BWG antenna. The temperature profile from the earth's surface to a depth of six feet over a time period of six months was used to optimize the placement of the fiber optic cables. In-situ evaluation of the fiber optic link performance indicates Allan deviation on the order of parts in 10(exp -15) at 1000 and 10,000 seconds averaging time; thus, the link stability degradation due to environmental conditions still preserves hydrogen maser stability at the user locations. This paper reports on the implementation of optical fibers and electro-optic devices for distributing very stable, low phase noise reference signals to remote BWG antenna locations. Allan deviation and phase noise test results for a 16 km fiber optic distribution link are presented in the paper

Hotline update of clinical trials and registries presented at the American College of Cardiology Congress 2010: ACCORD, INVEST, NAVIGATOR, RACE II, SORT OUT III, CSP-474, DOSE, ASPIRE and more

This article gives an overview on a number of novel clinical trials in the field of cardiovascular medicine, which were presented during the Late Breaking Clinical Trial Sessions at the 59th annual meeting of the American College of Cardiology in Atlanta, USA, from 14th March to 16th March 2010. The data were presented by leading experts in the field with relevant positions in the trials. These comprehensive summaries should provide the readers with the most recent data on diagnostic and therapeutic developments in cardiovascular medicine similar as previously reported (Schirmer SH, van der Laan AM, Bohm M, Mahfoud F in Clin Res Cardiol 98:691–699, 2009; Maier LS, Schirmer SH, Walenta K, Jacobshagen C, Bohm M in Clin Res Cardiol 98:413–419, 2009)

Long-term efficacy of a combination of amlodipine and olmesartan medoxomil±hydrochlorothiazide in patients with hypertension stratified by age, race and diabetes status: a substudy of the COACH trial

A prespecified subgroup analysis of a 44-week open-label extension study is presented. The efficacy and safety of the combination of amlodipine (AML)+ olmesartan medoxomil (OM), with and without the addition of hydrochlorothiazide (HCTZ), were investigated in patients aged ⩾65 and <65 years, Blacks and non-Blacks and patients with and without type 2 diabetes. After an 8-week double-blind, placebo-controlled portion of the study, patients initiated therapy on AML 5+OM 40 mg per day, were uptitrated stepwise to AML 10+OM 40 mg per day, with the addition of HCTZ 12.5 mg, and 25 mg if blood pressure (BP) goal was not achieved (<140/90 or <130/80 mm Hg for patients with diabetes). Endpoints included the change from baseline in mean seated systolic BP, mean seated diastolic BP and achievement of BP goal. BP decreased from baseline for all treatments in each prespecified subgroup. By the end of the study, BP goal was achieved in 61.0% of patients aged ⩾65 years, 68.1% of patients aged <65 years, 63.3% of Blacks, 67.8% of non-Blacks, 26.9% of patients with diabetes and 72.9% of patients without diabetes. The combination of AML+OM±HCTZ was efficacious, safe and well tolerated by these subgroups

HEART UK statement on the management of homozygous familial hypercholesterolaemia in the United Kingdom

This consensus statement addresses the current three main modalities of treatment of homozygous familial hypercholesterolaemia (HoFH): pharmacotherapy, lipoprotein (Lp) apheresis and liver transplantation. HoFH may cause very premature atheromatous arterial disease and death, despite treatment with Lp apheresis combined with statin, ezetimibe and bile acid sequestrants. Two new classes of drug, effective in lowering cholesterol in HoFH, are now licensed in the United Kingdom. Lomitapide is restricted to use in HoFH but, may cause fatty liver and is very expensive. PCSK9 inhibitors are quite effective in receptor defective HoFH, are safe and are less expensive. Lower treatment targets for lipid lowering in HoFH, in line with those for the general FH population, have been proposed to improve cardiovascular outcomes. HEART UK presents a strategy combining Lp apheresis with pharmacological treatment to achieve these targets in the United Kingdom (UK). Improved provision of Lp apheresis by use of existing infrastructure for extracorporeal treatments such as renal dialysis is promoted. The clinical management of adults and children with HoFH including advice on pregnancy and contraception are addressed. A premise of the HEART UK strategy is that the risk of early use of drug treatments beyond their licensed age restriction may be balanced against risks of liver transplantation or ineffective treatment in severely affected patients. This may be of interest beyond the UK

Comparative effectiveness of antihypertensive medication for primary prevention of cardiovascular disease: systematic review and multiple treatments meta-analysis

Background: We conducted a systematic review of evidence from randomized controlled trials to answer the following research question: What are the relative effects of different classes of antihypertensive drugs in reducing the incidence of cardiovascular disease outcomes for healthy people at risk of cardiovascular disease? Methods: We searched MEDLINE, EMBASE, AMED (up to February 2011) and CENTRAL (up to May 2009), and reference lists in recent systematic reviews. Titles and abstracts were assessed for relevance and those potentially fulfilling our inclusion criteria were then assessed in full text. Two reviewers made independent assessments at each step. We selected the following main outcomes: total mortality, myocardial infarction and stroke. We also report on angina, heart failure and incidence of diabetes. We conducted a multiple treatments meta-analysis using random-effects models. We assessed the quality of the evidence using the GRADE-instrument. Results: We included 25 trials. Overall, the results were mixed, with few significant dif-ferences, and with no drugclass standing out as superior across multiple outcomes. The only significant finding for total mortality based on moderate to high quality evidence was that beta-blockers (atenolol) were inferior to angiotensin receptor blockers (ARB) (relative risk (RR) 1.14; 95% credibility interval (CrI) 1.02 to 1.28). Angiotensin converting enzyme (ACE)- inhibitors came out inferior to calcium-channel blockers (CCB) regarding stroke-risk (RR 1.19; 1.03 to 1.38), but superior regarding risk of heart failure (RR 0.82; 0.69 to 0.94), both based on moderate quality evidence. Diuretics reduced the risk of myocardial infarction compared to beta-blockers (RR 0.82; 0.68 to 0.98), and lowered the risk of heart failure compared to CCB (RR 0.73; 0.62 to 0.84), beta-blockers (RR 0.73; 0.54 to 0.96), and alpha-blockers (RR 0.51; 0.40 to 0.64). The risk of diabetes increased with diuretics compared to ACE-inhibitors (RR 1.43; 1.12 to 1.83) and CCB (RR 1.27; 1.05 to 1.57). Conclusion: Based on the available evidence, there seems to be little or no difference between commonly used blood pressure lowering medications for primary prevention of cardiovascular disease. Beta-blockers (atenolol) and alpha-blockers may not be first-choice drugs as they were the only drug-classes that were not significantly superior to any other, for any outcomes

Beyond the Evidence of the New Hypertension Guidelines. Blood pressure measurement – is it good enough for accurate diagnosis of hypertension? Time might be in, for a paradigm shift (I)

Despite widespread availability of a large body of evidence in the area of hypertension, the translation of that evidence into viable recommendations aimed at improving the quality of health care is very difficult, sometimes to the point of questionable acceptability and overall credibility of the guidelines advocating those recommendations. The scientific community world-wide and especially professionals interested in the topic of hypertension are witnessing currently an unprecedented debate over the issue of appropriateness of using different drugs/drug classes for the treatment of hypertension. An endless supply of recent and less recent "drug-news", some in support of, others against the current guidelines, justifying the use of selected types of drug treatment or criticising other, are coming out in the scientific literature on an almost weekly basis. The latest of such debate (at the time of writing this paper) pertains the safety profile of ARBs vs ACE inhibitors. To great extent, the factual situation has been fuelled by the new hypertension guidelines (different for USA, Europe, New Zeeland and UK) through, apparently small inconsistencies and conflicting messages, that might have generated substantial and perpetuating confusion among both prescribing physicians and their patients, regardless of their country of origin. The overwhelming message conveyed by most guidelines and opinion leaders is the widespread use of diuretics as first-line agents in all patients with blood pressure above a certain cut-off level and the increasingly aggressive approach towards diagnosis and treatment of hypertension. This, apparently well-justified, logical and easily comprehensible message is unfortunately miss-obeyed by most physicians, on both parts of the Atlantic. Amazingly, the message assumes a universal simplicity of both diagnosis and treatment of hypertension, while ignoring several hypertension-specific variables, commonly known to have high level of complexity, such as: - accuracy of recorded blood pressure and the great inter-observer variability, - diversity in the competency and training of diagnosing physician, - individual patient/disease profile with highly subjective preferences, - difficulty in reaching consensus among opinion leaders, - pharmaceutical industry's influence, and, nonetheless, - the large variability in the efficacy and safety of the antihypertensive drugs. The present 2-series article attempts to identify and review possible causes that might have, at least in part, generated the current healthcare anachronism (I); to highlight the current trend to account for the uncertainties related to the fixed blood pressure cut-off point and the possible solutions to improve accuracy of diagnosis and treatment of hypertension (II)

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements