The late-time development of the Richtmyer–Meshkov instability

Measurements have been made of the growth by the Richtmyer–Meshkov instability of nominally single-scale perturbations on an air/sulfur hexafluoride (SF6) interface in a large shock tube. An approximately sinusoidal shape is given to the interface by a wire mesh which supports a polymeric membrane separating the air from the SF6. A single shock wave incident on the interface induces motion by the baroclinic mechanism of vorticity generation. The visual thickness delta of the interface is measured from schlieren photographs obtained singly in each run and in high-speed motion pictures. Data are presented for delta at times considerably larger than previously reported, and they are tested for self-similarity including independence of initial conditions. Four different initial amplitude/wavelength combinations at one incident shock strength are used to determine the scaling of the data. It is found that the growth rate decreases rapidly with time, ddelta/dt[proportional]t–p (i.e., delta[proportional]t1–p), where 0.67<~p<~0.74 and that a small dependence on the initial wavelength lambda0 persists to large time. The larger value of the power law exponent agrees with the result of the late-time-decay similarity law of Huang and Leonard [Phys. Fluids 6, 3765–3775 (1994)]. The influence of the wire mesh and membrane on the mixing process is assessed

Gamma power in rural Pakistani children: links to executive function and verbal ability

Children in low- and middle-income countries are at high risk of cognitive deficits due to environmental deprivation that compromises brain development. Despite the high prevalence of unrealized cognitive potential, very little is known about neural correlates of cognition in this population. We assessed resting EEG power and cognitive ability in 105 highly disadvantaged 48-month-old children in rural Pakistan. An increase in EEG power in gamma frequency bands (21–30 Hz and 31–45 Hz) was associated with better executive function. For girls, EEG gamma power also related to higher verbal IQ. This study identifies EEG gamma power as a neural marker of cognitive function in disadvantaged children in low- and middle-income countries. Elevated gamma power may be a particularly important protective factor for girls, who may experience greater deprivation due to gender inequality.This research was supported by Grand Challenges Canada Saving Brains Initiative Grant 0061-03. The preparation of this article also was supported by a Scholar's Award from the William T. Grant Foundation to Jelena Obradovic. (0061-03 - Grand Challenges Canada Saving Brains Initiative; William T. Grant Foundation)Published versio

Komunikasi Device-to-Device pada Jaringan Seluler 5G Menggunakan MmWave

This article discusses about device-to-device communication on 5G cellular networks using mmWave. Device-to-device communication will support 5G cellular technology, because it can be a solution to overcome the limitations of cellular coverage and service capacity. D2D can be used in a variety of applications. The main problem in D2D is that interference between signals in one cell will be very vulnerable to occur, so that effective resource management is needed. In addition, the use of D2D will also increase the complexity of a cellular system, in terms of resource management, interference, and also the routing required. Several studies have been carried out to create D2D communication that can be implemented effectively on 5G. One of them is research to perfect the load balancing scheme which is one of the functions obtained from D2D communication. Load balancing is the distribution of cellular traffic loads, using D2D the traffic load is channeled to communication between devices and reduces the burden on the main network

Determination of Saline Soils Specific Gravity

The existence of salts as part of the solid phase of the soil or dissolved within the pore fluid may cause significant errors in the values of specific gravity of such soils by using conventional determination methods. Errors may arise from effects of wrong measurements of weights or volumes that take place due to dissolution of the salt during testing, precipitation during drying or dehydration of the crystals of certain salts such as gypsum. To overcome this confusion, the standard procedure for specific gravity determination is reconsidered and the calculation methods are reanalyzed. Suggestions for a more adequate procedure for gypseous or other types of saline soils are presented and corrections required for computations are derived

Simultaneous Determination of Binary Mixture of Estradiol and Progesterone Using Different Spectrophotometric Methods

    أربع تقنيات طيفية مشتقة سريعة ودقيقة وبسيطة للغاية تم استخدامها  من أجل التقدير الكمي للمزيج الثنائي من استراديول والبروجسترون المصنّعة على شكل كبسولة. الطريقة الأولى هي قياس الصفرى للمشتق الأول تم اكتشاف السعات المشتقة عند طول موجة عبور صفرى239.27 و292.51 نانوميتر لتقدير استراديول و 249.19 نانوميتر للبروجسترون. الطريقة الثانية هى الطرح النسبي يتم التقدير البروجسترون عند 240 نانوميتر بعد طرح التداخل الذى يمارسه استراديول. الطريقة الثالثة هى طرح السعة المعدلة تم انشاؤه بأستخدام التحليل الطيفى المشتق والتلاعب الرياضي. الطريقة الرابعة هي تقنية نسبة الأمتصاص تم قياس الأمتصاصية لكلا الدواءين عند طولين موجيين نقطة الأمتصاص متساوية 2601=λ ونقطة امتصاص2402=λ لبروجسترون ويتم حساب التراكيز النهائية بواسطة معادلة Q. منحنى المعايرة خطي من 140 – 5 و 32 – 2 ميكرو غرام /مل لاستراديول وبروجسترون على التوالى. تم اختبار انتقائية التقنيات المقترحة بأستخدام توليفات تركيبة تم ا إنشاؤها فى المختبر وتم تقيمها بأستخدام طريقة الإضافة القياسية. بأستخدام ANOVAأحادى الأتجاه  تمت مقارنة مخرجات الطرق المقترحة ولم تضهرالنتيجة أي فروق ذات دلالة احصائية بين التقنيات المقترحة.Four rapid, accurate and very simple derivative spectrophotometric techniques were developed for the quantitative determination of binary mixtures of estradiol (E2) and progesterone (PRG) formulated as a capsule. Method I is the first derivative zero-crossing technique, derivative amplitudes were detected at the zero-crossing wavelength of 239.27 and 292.51 nm for the quantification of estradiol and 249.19 nm for Progesterone. Method II is ratio subtraction, progesterone was determined at λmax 240 nm after subtraction of interference exerted by estradiol. Method III is modified amplitude subtraction, which was established using derivative spectroscopy and mathematical manipulations. Method IIII is the absorbance ratio technique, absorbance of both medicines was measured at two wavelengths λ1= 260, -absorptive point and λ2=240max of progesterone. The Q equations were used to calculate the final concentrations. The calibration curve is linear from 5.0–140 and 2.0–32.0 µg/ml for estradiol and progesterone respectively. The proposed techniques' selectivity was tested using synthetic combinations created in the lab and assessed using the standard addition method. Using one-way ANOVA, the outputs of the proposed ways were compared, and the result showed no significant differences between the proposed techniques