A 30 GHz 5-TeV Linear Collider

We present parameters for a linear collider with a $3$ to $5$ TeV center-of-mass energy that utilizes conventional rf technology operating at a frequency around 30 GHz. We discuss the scaling laws and assumed limitations that lead to the parameters described and we compare the merits and liabilities of different technological options including rf power source, accelerator structure, and final focus system design. Finally, we outline the components of the collider while specifying the required alignment and construction tolerances

Update on the Talent aortic stent-graft: A preliminary report from United States phase I and II trials

AbstractPurpose: Phase I and phase II trials were conducted to determine the safety and efficacy of the Talent aortic stent-graft (Medtronic World Medical, Sunrise, Fla) in the treatment of infrarenal abdominal aortic aneurysms (AAA). This is a preliminary report of the technical results and 30-day clinical outcome of these trials. Methods: Multicenter prospective trials were conducted to test the Talent stent-graft in high-risk and low-risk patient populations with AAA, including phase I feasibility and phase II clinical trials. The low-risk study included concurrent surgical controls. Results: In the phase I trial, deployment success was achieved in 92% (23/25 patients), and initial technical success was 78% (18/23 implants without endoleak). The 30-day technical success rate was 96%, with six endoleaks that resolved spontaneously (without need for further intervention); and the 30-day mortality rate was 12% (3/25 patients). The phase II high-risk trial demonstrated a deployment success of 94% (119/127 patients) and an initial technical success of 86% (102/119 implants). The 30-day technical success rate was 96%, and the 30-day mortality rate was 1.5% (2/127 patients). The phase II low-risk trial included a first-generation and a second-generation Talent stent-graft. Deployment success rates were 97% and 99%, respectively, and technical success rates at 30 days were 97% and 96%, respectively. The 30-day mortality rate was 2% in the phase II low-risk first-generation device trial, and the adverse-event rate was 20%. Corresponding figures for the second-generation device were 0% and 1.8%, respectively. Conclusion: The Talent stent-graft can be deployed successfully and achieves endovascular exclusion in a large proportion of patients with AAA. Morbidity and mortality rates are acceptable. One-year clinical results and the comparison with concurrent surgical control subjects remain to be evaluated. (J Vasc Surg 2001;33:S146-9.

MicroRNAs show a wide diversity of expression profiles in the developing and mature central nervous system

A comprehensive analysis of the neuroanatomical expression profiles of 38 abundant conserved miRNAs in developing and adult zebrafish brain was performed

120kev Ar8+-li Collisions Studied By Near Uv And Visible Photon Spectroscopy

A spectroscopic analysis of light emitted in the 200-600 nm wavelength range by Ar7+, Ar6+ and Ar5+ ions after charge exchange in 120keV Ar8+-Li collisions is performed. Transitions with Δn = 1 and Δn = 2 for n = 8, 9, 10 and 11 states of Ar8 following single electron capture are identified and the production cross sections for n = 8 and n = 9 are deduced from emission cross sections and compared with those calculated by the three-body classical trajectory Monte-Carlo method. Lines due to double capture process were observed and identified as Rydberg transitions 3snl-3sn\u27l\u27 (n = 7, 8 and 9) in Ar VII. Lines due to triple electron capture process were found and identified as transitions 3s2nl-3s2n\u27ï and 3s3pnl- 3s3pril\u27(n = 7, 8) in Ar VI. The configurations produced during the collision provides evidence that electron-electron interaction play an important role in double and triple charge exchange processes. © 1993 IOP Publishing Ltd

Differential binding of neutralizing and non-neutralizing antibodies to native-like soluble HIV-1 Env trimers, uncleaved Env proteins, and monomeric subunits

Background: The trimeric envelope glycoproteins (Env) on the surface of HIV-1 virions are the targets for neutralizing antibodies (NAbs). No candidate HIV-1 immunogen has yet induced potent, broadly active NAbs (bNAbs). Part of the explanation may be that previously tested Env proteins inadequately mimic the functional, native Env complex. Trimerization and the proteolytic processing of Env precursors into gp120 and gp41 profoundly alter antigenicity, but soluble cleaved trimers are too unstable to serve as immunogens. By introducing stabilizing mutations (SOSIP), we constructed soluble, cleaved Env trimers derived from the HIV-1 subtype A isolate BG505 that resemble native Env spikes on virions both structurally and antigenically. Results: We used surface plasmon resonance (SPR) to quantify antibody binding to different forms of BG505 Env: the proteolytically cleaved SOSIP.664 trimers, cleaved gp120-gp41ECTO protomers, and gp120 monomers. Non-NAbs to the CD4-binding site bound only marginally to the trimers but equally well to gp120-gp41ECTO protomers and gp120 monomers, whereas the bNAb VRC01, directed to the CD4bs, bound to all three forms. In contrast, bNAbs to V1V2 glycan-dependent epitopes bound preferentially (PG9 and PG16) or exclusively (PGT145) to trimers. We also explored the antigenic consequences of three different features of SOSIP.664 gp140 trimers: the engineered inter-subunit disulfide bond, the trimer-stabilizing I559P change in gp41ECTO, and proteolytic cleavage at the gp120-gp41ECTO junction. Each of these three features incrementally promoted native-like trimer antigenicity. We compared Fab and IgG versions of bNAbs and validated a bivalent model of IgG binding. The NAbs showed widely divergent binding kinetics and degrees of binding to native-like BG505 SOSIP.664. High off-rate constants and low stoichiometric estimates of NAb binding were associated with large amounts of residual infectivity after NAb neutralization of the corresponding BG505.T332N pseudovirus. Conclusions: The antigenicity and structural integrity of cleaved BG505 SOSIP.664 trimers render these proteins good mimics of functional Env spikes on virions. In contrast, uncleaved gp140s antigenically resemble individual gp120-gp41ECTO protomers and gp120 monomers, but not native trimers. Although NAb binding to functional trimers may thus be both necessary and sufficient for neutralization, the kinetics and stoichiometry of the interaction influence the neutralizing efficacy of individual NAbs

A new method of RF power generation for two-beam linear colliders

In this paper we discuss a new approach to two-beam acceleration. The energy for RF production is initially stored in a long-pulse electron beam which is efficiently accelerated to about 1.2 GeV by a fully loaded, conventional, low frequency (~1 GHz) linac. The beam pulse length is twice the length of the high-gradient linac. Segments of this long pulse beam are compressed using combiner rings to create a sequence of higher peak power drive beams with gaps in between. This train of drive beams is distributed from the end of the linac against the main beam direction down a common transport line so that each drive beam can power a section of the main linac. After a 180-degree turn, each high-current, low-energy drive beam is decelerated in low-impedance decelerator structures, and the resulti ng power is used to accelerate the low-current, high-energy beam in the main linac. The method discussed here seems relatively inexpensive is very flexible and can be used to accelerate beams for lin ear colliders over the entire frequency and energy range

Pair contact process with a particle source

We study the phase diagram and critical behavior of the one-dimensional pair contact process (PCP) with a particle source using cluster approximations and extensive simulations. The source creates isolated particles only, not pairs, and so couples not to the order parameter (the pair density) but to a non-ordering field, whose state influences the evolution of the order parameter. While the critical point p_c shows a singular dependence on the source intensity, the critical exponents appear to be unaffected by the presence of the source, except possibly for a small change in beta. In the course of our study we obtain high-precision values for the critical exponents of the standard PCP, confirming directed-percolation-like scaling.Comment: 15 pages, 9 figure

Self-consistent description of nuclear compressional modes

Isoscalar monopole and dipole compressional modes are computed for a variety of closed-shell nuclei in a relativistic random-phase approximation to three different parametrizations of the Walecka model with scalar self-interactions. Particular emphasis is placed on the role of self-consistency which by itself, and with little else, guarantees the decoupling of the spurious isoscalar-dipole strength from the physical response and the conservation of the vector current. A powerful new relation is introduced to quantify the violation of the vector current in terms of various ground-state form-factors. For the isoscalar-dipole mode two distinct regions are clearly identified: (i) a high-energy component that is sensitive to the size of the nucleus and scales with the compressibility of the model and (ii) a low-energy component that is insensitivity to the nuclear compressibility. A fairly good description of both compressional modes is obtained by using a ``soft'' parametrization having a compression modulus of K=224 MeV.Comment: 28 pages and 10 figures; submitted to PR

Lack of benefits for prevention of cardiovascular disease with aspirin therapy in type 2 diabetic patients - a longitudinal observational study

<p>Abstract</p> <p>Background</p> <p>The risk-benefit ratio of aspirin therapy in prevention of cardiovascular disease (CVD) remains contentious, especially in type 2 diabetes. This study examined the benefit and harm of low-dose aspirin (daily dose < 300 mg) in patients with type 2 diabetes.</p> <p>Methods</p> <p>This is a longitudinal observational study with primary and secondary prevention cohorts based on history of CVD at enrolment. We compared the occurrence of primary composite (non-fatal myocardial infarction or stroke and vascular death) and secondary endpoints (upper GI bleeding and haemorrhagic stroke) between aspirin users and non-users between January 1995 and July 2005.</p> <p>Results</p> <p>Of the 6,454 patients (mean follow-up: median [IQR]: 4.7 [4.4] years), usage of aspirin was 18% (n = 1,034) in the primary prevention cohort (n = 5731) and 81% (n = 585) in the secondary prevention cohort (n = 723). After adjustment for covariates, in the primary prevention cohort, aspirin use was associated with a hazard-ratio of 2.07 (95% CI: 1.66, 2.59, p < 0.001) for primary endpoint. There was no difference in CVD event rate in the secondary prevention cohort. Overall, aspirin use was associated with a hazard-ratio of 2.2 (1.53, 3.15, p < 0.001) of GI bleeding and 1.71 (1.00, 2.95, p = 0.051) of haemorrhagic stroke. The absolute risk of aspirin-related GI bleeding was 10.7 events per 1,000 person-years of treatment.</p> <p>Conclusion</p> <p>In Chinese type 2 diabetic patients, low dose aspirin was associated with a paradoxical increase in CVD risk in primary prevention and did not confer benefits in secondary prevention. In addition, the risk of GI bleeding in aspirin users was rather high.</p