Electron-positron pair creation in a vacuum by an electromagnetic field in 3+1 and lower dimensions

We calculate the probability of electron-positron pair creation in vacuum in 3+1 dimensions by an external electromagnetic field composed of a constant uniform electric field and a constant uniform magnetic field, both of arbitrary magnitudes and directions. The same problem is also studied in 2+1 and 1+1 dimensions in appropriate external fields and similar results are obtained.Comment: REVTeX, 10 pages, no figure, a brief note and some more references added in the proo

Scattering by a contact potential in three and lower dimensions

We consider the scattering of nonrelativistic particles in three dimensions by a contact potential $\Omega\hbar^2\delta(r)/ 2\mu r^\alpha$ which is defined as the $a\to 0$ limit of $\Omega\hbar^2\delta(r-a)/2\mu r^\alpha$. It is surprising that it gives a nonvanishing cross section when $\alpha=1$ and $\Omega=-1$. When the contact potential is approached by a spherical square well potential instead of the above spherical shell one, one obtains basically the same result except that the parameter $\Omega$ that gives a nonvanishing cross section is different. Similar problems in two and one dimensions are studied and results of the same nature are obtained.Comment: REVTeX, 9 pages, no figur

Lifestyle Profile of Elderly Living with Non-communicable Disease in Bangkok and Surabaya

Lifestyle is one of the underlying risk factor of non-communicable disease (NCD). Dietary habit and exercise pattern are two indicators of lifestyle. Elderly are prone to NCD due to increased age which being independent risk factor. This study aimed to analyze and compare the lifestyle profile of elderly living with NCD between Bangkok and Surabaya, in term of dietary habit and exercise pattern, and to determine the best predictor of sedentary lifestyle among this population. This cross-sectional study involved 100 and 96 elderly with HT and/or DM in communities of Bangkok and Surabaya respectively (n=196). Self-developed instrument was used in data collection (r=0.178–0.715, Chronbach Alpha=0.644). Mann-Whitney U and regression tests were used in data analysis (α<0.05). There was a significant difference of lifestyle in elderly living with NCD between Bangkok and Surabaya (p=0.008), especially in term of eat variety food (p=0.002), oily food (p=0.015), and curry with coconut milk (p=0.026). Eat vegetable and fruit could not predict dietary habit in elderly living with NCD (p=0.064). Eat fermented food was came up as the best predictor of lifestyle (p=0.000). It was accounted for 52.1% variance in lifestyle score in this population

Comparison of Blood Pressure and Blood Glucose Level Among Elderly with Non-communicable Disease

Due to increasing age, elderly are prone to non-communicable diseases (NCD), such as hypertension (HT) and diabetes mellitus (DM). Easy physical condition monitoring of people with HT and/or DM is by measuring their blood pressure (BP) and/or blood glucose level (BGL) periodically. This study aimed to compare and analyze the differences of BP and BGL among elderly with HT and/or DM in Bangkok and Surabaya. This cross-sectional study involved 100 and 96 elderly with HT and/or DM in communities of Bangkok and Surabaya respectively (n=196). There were three groups of samples which consisted of 60 DM, 68 HT, and 68 DM&HT cases. Instruments used were demography questionnaire, sphygmomanometer, and glucometer. Test of one-way ANOVA, Least Significant Difference (LSD), Kruskal-Wallis, and Mann-Whitney U were used for data analysis (α<.05). There was a significant difference of systolic and diastolic BP found between groups (p=.000 and p=.011 respectively), but no difference found between the groups of HT and DM&HT (p=.657 and p=.330 respectively). There was a significant difference of BGL found between groups (p=.002), but no difference found between the groups of HT and DM (p=.075) and between the groups of DM and DM&HT (p=.066). BP is significantly different between the group of HT and DM in term of systole and diastole, especially in elderly, but BGL is similar. The risk of being HT for elderly with DM is very high. Elderly with DM&HT have high BP and BGL similarly to those with single disease of HT or DM

Giant Impact Induced Atmospheric Blow-Off

Previous calculations indicate that the Earth suffered impacts from objects up to Mars size. Such a giant impact may have produced a temporary ejecta-based ring that accreted to form the Moon. To simulate the surface waves from such events we approximated the cratering source as a buried pressurized sphere. For a 10^27 J impactor we calculated the resulting surface wave using the mode summation method of Sato et al.. For such an impact, the solid Earth free-surface velocity above, and antipodal to, the source achieves 2.6 and 1.9 km/s. Such large ground motions pump the atmosphere and result in upward particle motions which cause the atmosphere to be accelerated to excess of the escape velocity (11.2 km/s) at high altitudes. For a 1.3 × 10^32 J Moon-forming impact we calculate that ~50% of the Earth's atmosphere is accelerated to escape

Suspension of the fiber mode-cleaner launcher and measurement of the high extinction-ratio (10^{-9}) ellipsometer for the Q & A experiment

The Q & A experiment, first proposed and started in 1994, provides a feasible way of exploring the quantum vacuum through the detection of vacuum birefringence effect generated by QED loop diagram and the detection of the polarization rotation effect generated by photon-interacting (pseudo-)scalar particles. Three main parts of the experiment are: (1) Optics System (including associated Electronic System) based on a suspended 3.5-m high finesse Fabry-Perot cavity, (2) Ellipsometer using ultra-high extinction-ratio polarizer and analyzer, and (3) Magnetic Field Modulation System for generating the birefringence and the polarization rotation effect. In 2002, the Q & A experiment achieved the Phase I sensitivity goal. During Phase II, we set (i) to improve the control system of the cavity mirrors for suppressing the relative motion noise, (ii) to enhance the birefringence signal by setting-up a 60-cm long 2.3 T transverse permanent magnet rotatable to 10 rev/s, (iii) to reduce geometrical noise by inserting a polarization-maintaining optical fiber (PM fiber) as a mode cleaner, and (iv) to use ultra-high extinction-ratio (10^{-9}) polarizer and analyzer for ellipsometry. Here we report on (iii) & (iv); specifically, we present the properties of the PM-fiber mode-cleaner, the transfer function of its suspension system, and the result of our measurement of high extinction-ratio polarizer and analyzer.Comment: 8 pages, 6 figures, presented in the 6th Edoardo Amaldi Conference on Gravitational Waves, Okinawa, Japan, June 2005, and accepted by "Journal of Physics: Conference Series". Modifications from version 2 were made based on the referees' comments on figures. Ref. [31] were update