Testing the nonlinearity of the BVIcJHKs period-luminosity relations for the Large Magellanic Cloud Cepheids

A number of recent works have suggested that the period-luminosity (PL) relation for the Large Magellanic Cloud (LMC) Cepheids exhibits a controversial nonlinear feature with a break period at 10 days. Therefore, the aim of this Research Note is to test the linearity/nonlinearity of the PL relations for the LMC Cepheids in BVIcJHKs band, as well as in the Wesenheit functions. We show that simply comparing the long and short period slopes, together with their associate d standard deviations, leads to a strictly larger error rate than applying rigorous statistical tests such as the F-test. We applied various statistical tests to the current published LMC Cepheid data. These statistical tests include the F-test, the testimator test, and the Schwarz information criterion (SIC) method. The results from these statistical tests strongly suggest that the LMC PL relation is nonlinear in BVIcJH band but linear in the Ks band and in the Wesenheit functions. Using the properties of period-color relations at maximum light and multi-phase relations, we believe that the nonlinear PL relation is not caused by extinction errors.Comment: 6 pages, 5 figures and 2 tables, A&A accepte

Stress-strength reliability for designs based on large historic values of stress

AbstractSome new ideas and thoughts concerning the definition and calculation of reliability for stress-strength models for failure are presented. In particular, calculations are carried out and statistical inference is made for systems whose design is made on the basis of the past data with emphasis on extremes and excesses. This is done based on the observation that for such designs reliability estimation can be viewed as the statistical problem of comparing future values, with large values of the past for a single distribution. It is discussed that this approach could particularly prove useful when no basis exists for assuming any specific distributions for either stress or strength or both, but when design is made or experimentation has been performed yielding sufficient information to assume a certain functional relationship between distributions for stress and strength. Some ideas from information theory are also brought in to provide a guideline for defining reliability on the basis of an “equivalent” system. Finally, a simple demonstrating example is also included using a set of published data

Comparative study between effectiveness of Treadmill Training with partial body weight support and Physiotherapy Versus Treadmill training in improving gait ability of hemiparatic patients.

INTRODUCTION : Stroke may be manifested as Hemiplegia, which is the paralysis of muscles of one side of the body, contralateral to the side of the brain in which CVA occurred. Clinically a variety of deficits are possible including the changes in the level of consciousness, impairments of sensory, motor, cognitive, perceptual and language functions. The locations of lesion, the extent of lesion, and the amount of collateral blood flow and early acute care management determine the severity of neurological deficits. AIM : To compare the effectiveness of treadmill training with partial body weight support and physiotherapy in improving gait ability of stroke patients . Treadmill training alone. OBJECTIVES : 1. To determine the effect if treadmill training with partial body weight support and physiotherapy in improving gait ability of stroke patients in group A subjects. 2. To determine the effect of treadmill training alone in improving gait ability of stroke patients in group B. 3. To determine the difference between the effectiveness of treadmill training with partial body weight support and physiotherapy in improving gait ability of stroke patients. MATERIALS AND METHODS : A total Number of 30 patient with stroke were selected by random sampling method with consideration of inclusion criteria and exclusion criteria and they were divided in to Group A and Group B. All patients participated in comprehensive 6 months Rehabilitation program • A three week baseline study consisted of daily physiotherapy, occupation therapy, speech and neuro physiological therapy according to individual needs. • During the subsequent 3 weeks of specific intervention. • Group A - Treadmill training with partial body weight support for 30 minutes 5 time a week plus single treatment session of physiotherapy for 40 minutes 5 times a week For 3 weeks. • Group B - Treadmill training with partial body weight support for 30 minutes 5 times a week for 3 weeks. RESULTS : This study has proved the 3 week combination of treadmill training with BWS and physiotherapy effected a large improvement of a gait ability of non-ambulatory hemi paretic subjects than an exclusive 3- week treadmill therapy with BWS. CONCLUSION : From the results of this study 3 weeks of treadmill training with BWS pulls physiotherapy accelerated the restoration of gait ability in chronic hemi paretic subjects; correspondingly, a focused and intense treatment regime including locomotion training seems most promising in gait rehabilitation after stroke. The result was analyzed using (mean/ mean difference) which proved that the use of treadmill training with partial body weight support combined with physiotherapy to be more effective in improving gait ability in hemi paretic patients

A stochastic model for sero conversion times of HIV transmission

This paper focuses on the study of a Stochastic Model for predicting the seroconversion time of HIV transmission. As the immune capacities of an individual vary and also have its own resistance, the antigenic diversity threshold is different for different person. We propose a stochastic model to study the damage process acting on the immune system that is non- linear. The mean of seroconversion time of HIV and its variance are derived. A numerical example is given to illustrate the seroconversion times of HIV transmission

Investigations of the Non-Linear LMC Cepheid Period-Luminosity Relation with Testimator and Schwarz Information Criterion Methods

In this paper, we investigate the linearity versus non-linearity of the Large Magellanic Cloud (LMC) Cepheid period-luminosity (P-L) relation using two statistical approaches not previously applied to this problem: the testimator method and the Schwarz Information Criterion (SIC). The testimator method is extended to multiple stages for the first time, shown to be unbiased and the variance of the estimated slope can be proved to be smaller than the standard slope estimated from linear regression theory. The Schwarz Information Criterion (also known as the Bayesian Information Criterion) is more conservative than the Akaike Information Criterion and tends to choose lower order models. By using simulated data sets, we verify that these statistical techniques can be used to detect intrinsically linear and/or non-linear P-L relations. These methods are then applied to independent LMC Cepheid data sets from the OGLE project and the MACHO project, respectively. Our results imply that there is a change of slope in longer period ranges for all of the data sets. This strongly supports previous results, obtained from independent statistical tests, that the observed LMC P-L relation is non-linear with a break period at/around 10 days.Comment: 9 pages, 5 figures and 3 tables, PASP accepte

Multiphysics Analysis of a Magnetorheological Damper

     A Magnetorheological damping has evolved as a potential tool in vibration control. The design of magnetorheological damping involves analysis of fluid flow principles and electromagnetic flux analysis. This research paper involves design and analysis of a magnetorheological damper employed for vibration control. The analysis is carried over by considering the domain as an axisymmetric model. The damping force of the damper depends upon the shear stress due to fluid viscosity and yield stress induced due to magnetic flux applied. The damping force generated by the damper is calculated

High Performance Pre-computation based Self-Controlled Precharge-Free Content-Addressable Memory

Content-addressable memory (CAM) is a special type of memory used in networking applications for very-high-speed searching operation. It compares input search data with the table of stored data, and returns the address of matching data in a parallel search method. Also the use of parallel comparison results in reduced search time, it also significantly increases power consumption when compared to precharge based CAM. The low-power NAND-type and high-speed NOR-type CAM methods require the precharge prior to the search. This PF phase leads to increase the settling time of the output and also reduce the speed of the search operation. In this paper, a High performance Pre-computation Based Self-Controlled Precharge-Free CAM (PB-SCPF CAM) structure is proposed for high-speed applications which reduce the settling time as well as improve the speed of the search. Where search time is very important for designing larger word lengths, SCPF architecture is efficacious in applications. The experimental results show that PB-SCPF approach can attain on average 32% in power reduction and 80% in delay reduction. The most important contribution of this project is that it offers theoretical and practical proofs to verify that our suggested PB-SCPF CAM system can achieve greater power reduction without the requirement of special CAM cell design. This shows that the approach which we have used is more flexible and adaptive for general designs and high speed applications

Period-Luminosity Relations Derived from the OGLE-III Fundamental Mode Cepheids

In this Paper, we have derived Cepheid period-luminosity (P-L) relations for the Large Magellanic Cloud (LMC) fundamental mode Cepheids, based on the data released from OGLE-III. We have applied an extinction map to correct for the extinction of these Cepheids. In addition to the VIW band P-L relations, we also include JHK and four Spitzer IRAC band P-L relations, derived by matching the OGLE-III Cepheids to the 2MASS and SAGE datasets, respectively. We also test the non-linearity of the Cepheid P-L relations based on extinction-corrected data. Our results (again) show that the LMC P-L relations are non-linear in VIJH bands and linear in KW and the four IRAC bands, respectively.Comment: 6 pages, 3 figures and 3 tables, ApJ accepte

Controlled Exposure Study of Air Pollution and T-Wave Alternans in Volunteers without Cardiovascular Disease

Background: Epidemiological studies have assessed T-wave alternans (TWA) as a possible mechanism of cardiac arrhythmias related to air pollution in high-risk subjects and have reported associations with increased TWA magnitude. Objective: In this controlled human exposure study, we assessed the impact of exposure to concentrated ambient particulate matter (CAP) and ozone (O:3) on T-wave alternans in resting volunteers without preexisting cardiovascular disease. Methods: Seventeen participants without preexisting cardiovascular disease were randomized to filtered air (FA), CAP (150 μg/m3), O3 (120 ppb), or combined CAP + O3 exposures for 2 hr. Continuous electrocardiograms (ECGs) were recorded at rest and T-wave alternans (TWA) was computed by modified moving average analysis with QRS alignment for the artifact-free intervals of 20 beats along the V2 and V5 leads. Exposure-induced changes in the highest TWA magnitude (TWAMax) were estimated for the first and last 5 min of each exposure (TWAMax_Early and TWAMax_Late respectively). ΔTWAMax (Late–Early) were compared among exposure groups using analysis of variance. Results: Mean ± SD values for ΔTWA:Max were –2.1 ± 0.4, –2.7 ± 1.1, –1.9 ± 1.5, and –1.2 ± 1.5 in FA, CAP, O3, and CAP + O3 exposure groups, respectively. No significant differences were observed between pollutant exposures and FA. Conclusion: In our study of 17 volunteers who had no preexisting cardiovascular disease, we did not observe significant changes in T-wave alternans after 2-hr exposures to CAP, O:3, or combined CAP + O3. This finding, however, does not preclude the possibility of pollution-related effects on TWA at elevated heart rates, such as during exercise, or the possibility of delayed responses