SuperWeb: research issues in Java-based global computing

The Internet, in particular the World Wide Web, continues to expand at an amazing pace. We propose a new infrastructure, SuperWeb, to harness global resources, such as CPU cycles or disk storage, and make them available to every user on the Internet. SuperWeb has the potential for solving parallel supercomputing applications involving thousands of co-operating components on the Internet. However, we anticipate that initial implementations will be used inside large organizations with large heterogeneous intranets. Our approach is based on recent advances in Internet connectivity and the implementation of safe distributed computing realized by languages such as Java. Our SuperWeb prototype consists of brokers, clients and hosts. Hosts register a fraction of their computing resources (CPU time, memory, bandwidth, disk space) with resource brokers. Clients submit tasks that need to be executed. The broker maps client computations onto the registered hosts. We examine an economic model for trading computing resources, and discuss several technical challenges associated with such a global computing environment. © 1997 John Wiley & Sons, Ltd.     

Profiling techniques for communication in fine‐grained parallel languages

Fine tuning the performance of large parallel programs is a very difficult task. A profiling tool can provide detailed insight into the utilization and communication of the different processors, which helps identify performance bottlenecks. In this paper we present two profiling techniques for the fine‐grained parallel programming language Split‐C, which provides a simple global address space memory model. One profiler provides a detailed analysis of a program's execution. The other profiler collects cumulative information. As our experience shows, it is quite challenging to profile programs that make use of efficient, low‐overhead communication. We incorporated techniques which minimize profiling effects on the running program, and quantified the profiling overhead. We present several Split‐C applications showing that the profiler is useful in determining performance bottlenecks. Copyright © 1999 John Wiley & Sons, Ltd.     

An InP solar cell with a light-trapping front surface

Low-angle (311) V-grooves can be produced on a (100) InP surface by a maskless anisotropic etch. This can reduce the surface reflectivity of a glass-covered InP solar cell. Light reflected from grooved surface is trapped by total internal reflection at the glass/air interface and directed back to the solar cell. Results from ITO/InP solar cells on low-angle V-grooved substrates are presented, showing a 5.8% increase in short-circuit current, and a nearly equal rise in efficiency.     

Bicycle injury events among older adults in Northern Sweden: A 10-year population based study

Bicycles are a common mode of transportation and injured bicyclists cause a substantial burden on the medical sector. In Sweden, about half of fatally injured bicyclists are 65 years or older. This study analyzes the injury mechanisms, injuries, and consequences among bicyclists 65 years or older and compare with younger bicyclists (≤64) and older adults as passenger car drivers, to give a basis for an injury preventive discussion for this age group. Umeå University Hospital's primary catchments area had 142,000 inhabitants in 2006. Nearly all injured road users in the well-defined geographic area are treated at this hospital and a 10-year data set (N = 456) of injured bicyclists aged 65+ from the hospital's continuous injury registration (1997-2006) was analyzed. The results show that the annual injury incidence was 2.4 and 2.2 per 1000 men and women, respectively, aged 65 or older. For men the incidence rate was constant in the three age groups 65-74, 75-84 and 85+, while it decreased strongly for women. The incidence rate for old adults as passenger car drivers and younger bicyclists was 1.0 and 4.6, respectively. Most frequent injury mechanisms were falls when getting on or off a bicycle (20%) and by potholes or irregularities on the ground, edge of a sidewalk, or similar (13%). Only 6% were hit by cars, trucks, or buses. Half of the injured suffered fractures or dislocations, and 10% suffered concussion or more serious intracranial injuries. Getting on or off the bicycle caused most fractures (especially a high fraction of the hip and femur fractures) and resulted in 27% of all inpatient days in hospital. Three individuals died. One-third of the injured were treated as inpatients for a total of 1413 days (on average 9 days), with 69% of the days being caused by fractures. The cost for out- and inpatient acute treatment was approximately USD 4700 (SEK 33,000) per injured. The results merit an interest for this target group; bicycle injuries among older adults are costly both for the individual and the medical sector. Injury mitigation strategies focused on the needs of this group are probably as well motivated as those focused on older car drivers.     

A period-processor-time-minimal schedule for cubical meshalgorithms

Using a directed acyclic graph (dag) model of algorithms, we investigate precedence-constrained multiprocessor schedules for the n×n×n directed mesh. This cubical mesh is fundamental, representing the standard algorithm for square matrix product, as well as many other algorithms. Its completion requires at least 3^n-2 multiprocessor steps. Time-minimal multiprocessor schedules that use as few processors as possible are called processor-time-minimal. For the cubical mesh, such a schedule requires at least [3n²/4] processors. Among such schedules, one with the minimum period (i.e., maximum throughput) is referred to as a period-processor-time-minimal schedule. The period of any processor-time-minimal schedule for the cubical mesh is at least 3^n/2 steps. This lower bound is shown to be exact by constructing, for n a multiple of 6, a period-processor-time-minimal multiprocessor schedule that can be realized on a systolic array whose topology is a toroidally connected n/2×n/2×3 mesh     

A comparison study: The new extended shelf life isopropyl ester PMR technology versus the traditional methyl ester PMR approach

Polymerization of monomeric reactants (PMR) monomer solutions and carbon cloth prepregs of PMR II‐50 and VCAP‐75 were prepared using both the traditional limited shelf life methanol based PMR approach and a novel extended shelf life isopropanol based PMR approach. The methyl ester and isopropyl ester based PMR monomer solutions and PMR prepregs were aged for up to 4 years at freezer and room temperatures. The aging products formed were monitored using high pressure liquid chromatography (HPLC). The composite processing flow characteristics and volatile contents of the aged prepregs were correlated versus room temperature storage time. Composite processing cycles were developed and six‐ply cloth laminates were fabricated with prepregs after various extended room temperature storage times. The composites were then evaluated for glass transition temperature (T_g), thermal decomposition temperature (T_d), initial flexural strength (FS), and modulus (FM), long term (1000 h at 316°C) thermal oxidative stability (TOS), and retention of FS and FM after 1000 h aging at 316°C. The results for each ester system were comparable. Freezer storage was found to prevent the formation of aging products for both ester systems. Room temperature storage of the novel isopropyl ester system increased PMR monomer solution and PMR prepreg shelf life by at least an order of magnitude, while maintaining composite thermal and mechanical properties. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3549–3564, 2006     

Utility of a linear array ultrasound endoscope in the evaluation of suspected pancreatic disease

Diethylcarbamazine (DEC) was discovered in 1947 as a potent therapeutic agent in lymphatic filariasis and has been a mainstay of antifilarial therapy over the past five decades (R. I. Hewitt, et al., 1947, Journal of Laboratory and Clinical Medicine 32, 1304-1313). Several hundred million doses of this drug have been administered to people. Despite its widespread and successful use over this prolonged time scale, its mechanism of action remains obscure (R. M. Maizels and D. A. Denham, 1992, Parasitology 105 Suppl. 549-560). Numerous studies suggest that DEC has no direct effect on the parasite (F. Hawking and W. Laurie, 1949, Lancet 2, 146-147) and that it exerts its action by stimulating host immune defense mechanisms (F. Hawking et al., 1948, Lancet 2, 730-731), or by activating host platelets to become microfilaricidal (J. Y. Cesbron et al., 1987, Nature 325(6104) 533-536). Recent data from two different laboratories suggest that NO may be involved in host defense against filarial parasites (T. V. Rajan et al., 1996, Infection and Immunity 64(8), 3351-3353; M. J. Taylor et al., 1996, Parasitology 112, 315-322). We investigated whether DEC stimulates the production of NO from murine macrophages or rat endothelial cells. DEC did not stimulate the synthesis or secretion of NO from either, nor did it synergize with interferon-gamma or tumor necrosis factor-alpha in the induction of inducible NO synthase (iNOS). In addition, there was no consistent increase in the output of inorganic nitrate, the end product of NO metabolism, in the urines of rats treated with DEC. These data suggest that DEC does not achieve its therapeutic efficacy through the induction of host iNOS.     

Low- versus high-dose azithromycin triple therapy for Helicobacter pylori infection

BACKGROUND: We report a clinical trial which evaluated the effectiveness of triple therapy containing low- and high-dose azithromycin to treat Helicobacter pylori infection. METHODS: From March 1997 to March 1998, patients infected with H. pylori were assigned to receive either: Treatment 1: ranitidine bismuth citrate (RBC) (400 mg b.d.) and amoxycillin (1 g b.d.) for 10 days with azithromycin 500 mg o.m. for 3 days: or Treatment 2: RBC and amoxycillin for 10 days with azithromycin 1 g o.m. for 3 days. H. pylori eradication was established by a urea breath test at least 4 weeks after therapy. Side-effects and compliance were assessed using a diary. RESULTS: Sixty-eight patients were enrolled. Fifty-seven per cent of patients were treated for active peptic ulcer disease or a history of peptic ulcer disease. Treatment 1 cured H. pylori in 44% and 44% by per protocol and intention-to-treat analysis, respectively. The corresponding eradication rates for Treatment 2 were 79% and 75%. Two patients taking Treatment 2 dropped out of the study because of side-effects. CONCLUSIONS: With RBC and amoxycillin for 10 days, azithromycin at a dose of 1 g/day for 3 days was significantly better at curing H. pylori infection than azithromycin 500 mg/day for 3 days.     

Prevalence of vision and ocular disease conditions in a clinical pediatric population

BACKGROUND: The purpose of this study was to fill a significant void in the ophthalmic literature by performing a large scale, comprehensive, prospective study of the prevalence of vision disorders and ocular pathology in a clinical pediatric population using well-defined diagnostic criteria. METHODS: A prospective study was performed on 2,023 consecutive patients between the ages of 6 months and 18 years presenting for an initial comprehensive examination at the Eye Institute of The Pennsylvania College of Optometry. There were 373 subjects between 6 months and 5 years, 11 months of age, and 1,650 subjects between 6 years and 18 years of age. RESULTS: The most important finding from this study is that other than refractive anomalies, the most common conditions optometrists are likely to encounter in a pediatric population are binocular vision and accommodative disorders. The prevalence of accommodative and binocular (strabismic and non-strabismic) vision disorders is 9.7 times greater than the prevalence of ocular disease in children 6 months to 5 years of age, and 8.5 times greater than the prevalence of ocular disease in children 6 to 18 years of age. CONCLUSIONS: The data from this study has great significance for clinicians, optometric educational institutions, health care planners, and administrators. This data suggests that other than refractive anomalies, the most prevalent conditions in the clinical pediatric population are binocular and accommodative disorders. Clinicians should use a minimum data base that includes assessments of accommodation and binocular vision that will allow them to detect conditions with the highest prevalence.     

Low-intensity low-temperature (LILT) measurements and coefficients on new photovoltaic structures

Past NASA missions to Mars, Jupiter and the outer planets were powered by radioisotope thermal generators. Although these devices proved to be reliable, their high cost and highly toxic radioactive heat source has made them far less desirable for futur e planetary missions. This has resulted in a renewed search for alternate energy sources, some of them being photovoltaics (PV) and thermophotovoltaics. Both of these alternate energy sources convert light/thermal energy directly into electricity. In order to create a viable PV database for planetary mission planners and cell designers, we have compiled low-intensity low-temperature (LILT) I-V data on single-junction and multi-junction high-efficiency solar cells. The cells tested here represent the latest PV technology. Using these LILT data to calculate short-circuit current, open-circuit voltage and fill factor as a function of temperature and intensity, an accurate prediction of cell performance under the AMO spectrum can be determined. When combined with quantum efficiency at low temperature data, one can further enhance the data by adding spectral variations to the measurements. This paper presents an overview by LILT measurements and is only intended to be used as a guideline for material selection and performance predictions. As single-junction and multi-junction cell technologies emerge, new test data must be collected. Cell materials included are Si, GaAs/Ge, GaInP/GaAs/GaAs, InP, InGaAs/InP, InP/InGaAs/InP and GaInP. Temperatures range down to as low as — 180°C and intensities range from 1 sun down to 0.02 sun. The coefficients presented in this paper represent experimental results and are intended to provide the user with approximate numbers.