Optimization of Wi-Fi Direct average time to discovery: A Global Channel Randomization Approach

The main objective of this work is to propose concrete time reduction strategies for discovery of Wi-Fi Direct in Android. To achieve our goals, we perform a fairly general mathematical modeling of the discovery of devices using Poisson processes. Subsequently, under asymptotic invariance hypotheses of certain distributions, we derive formulas for the expected time to discovery. We provide sufficient condition for fast convergence to an invariant distribution and determine key decision parameters (jumps intensities) that minimize the average time to discovery. We also propose a predictive model for rapid evaluation of these optimal discovery parameters. Experimental tests in an emulator are also conducted to validate the theoretical results obtained. A comparative performance study is done with some optimization approaches from literature. Compared with existing methods, the improvement of the average time discovery we obtained with the proposed method is above 98.34%.

Durotaxis of passive nanoparticles on elastic membranes

The transport of macromolecules and nanoscopic particles to a target cellular site is a crucial aspect in many physiological processes. This directional motion is generally controlled via active mechanical and chemical processes. Here we show, by means of molecular dynamics simulations and an analytical theory, that completely passive nanoparticles can exhibit directional motion when embedded in non-uniform mechanical environments. Specifically, we study the motion of a passive nanoparticle adhering to a mechanically non-uniform elastic membrane. We observe a non-monotonic affinity of the particle to the membrane as a function of the membrane's rigidity, which results in the particle transport. This transport can be both up or down the rigidity gradient, depending on the absolute values of the rigidities that the gradient spans across. We conclude that rigidity gradients can be used to direct average motion of passive macromolecules and nanoparticles on deformable membranes, resulting in the preferential accumulation of the macromolecules in regions of certain mechanical properties.

The balance of photosynthetic pigments pools and phenolic compounds in dwarf shrubs on the weakly disrupted territory

The paper identifies photosynthetic pigments pools balance and phenolic compounds in suffruticous species of Vaccinium myrtillus L. and Vaccinium vitis-idaea L. on the Tundrinsky bor territory (Khanty-Mansi Autonomous Okrug - Yugra) for the purpose of ecological and biochemical assessment of the valuable plant species status. The authors carry out a comparative analysis of the studied biochemical parameters (chlorophyll a , chlorophyll b , carotenoids and phenolic compounds) of two species leaves, collected from two sample plots similar in landscape and soil and hydrological conditions of the weakly disrupted territory of the Tundrinsky bor territory. The analysis of the suffruticous species leaves for chlorophyll content revealed the following distribution of chlorophyll pools: chlorophyll a - 64,96%, chlorophyll b - 35,04% for leaves of Vaccinium myrtillus and chlorophyll a - 68,28%, chlorophyll b - 31, 72% for leaves of Vaccinium vitis-idaea . The average content of carotenoids and phenolic compounds of Vaccinium myrtillus leaves was 0,62 0,11 mg/g and 14,18 1,65 mg/g, respectively, in Vaccinium vitis-idaea leaves - 0,52 0,12 mg/g and 18,79 2,25 mg/g, respectively. The correlation analysis showed the presence of a direct average strength correlation (r = 0,4) between the levels of chlorophyll and phenolic compounds in the leaves of Vaccinium vitis-idaea .

New ultrasound marker to assess the cervix when predicting preterm birth in the first trimester of pregnancy

The marker for preterm labor in routine practice at this time is only the measurement of the length of the cervix. However, the low sensitivity of this test (approximately 38 % in the first trimester of pregnancy) initiates a search for new markers of the threat of preterm labor. The indicators of the glandular zone of the cervical canal (GI, CGA, EGE), studied using statistical methods in the first trimester of pregnancy, showed the presence of a direct average correlation strength of this indicators and the term of labor, the sensitivity of 57 % with a specificity of 98,9 %. Thus, performing cervicometry during pregnancy, especially in early periods, it is necessary to evaluate not only the length, but also the structure of the cervix. The echo negative zone of the cervical canal is presented to the authors of this article as a kind of "ultrasonic marker for fibronectin" and undoubtedly requires further study.

Uncertainty in acquiring elemental fluxes from subtropical mountainous rivers

Mountainous watersheds in high standing islands of the western tropical and subtropical Pacific have received great international attention regarding its high physical and chemical weathering rates caused by cyclone invasion, friable lithology and high tectonic activity. Since mountainous region is usually difficult to assess, particularly, during severe weather conditions, hydrological responses of elements against full-scale of water discharge (often >2 orders of magnitude) are rarely reported. In this study, we conducted discrete sampling (~3 day interval) throughout four seasons and intensive sampling (hourly) during typhoon floods from three upstream watersheds in Taiwan during 2002–2005. These observations revealing various elemental responses are taken as complete dataset (i.e. reference flux) to evaluate flux uncertainty among constituents caused by different sampling frequency, sample size and estimators. Five constituents are analyzed, including nitrate (NO3), sulfate (SO4), dissolved organic carbon (DOC), calcium (Ca), and silicate (Si). Each has specific environmental and geological implications. Direct average, flow-weighted and rating curve methods were applied. Basing on statistical analyses, flow-weighted method is the most conservative method, and is recommended to use for all constituents if few samples are available. The rating curve method is suggested, only when water samples in high-flows are available. Direct average method is only appropriate for stable constituents, such as Si. These findings, such as concentration-discharge variation, sampling frequency effect, and flux estimator assessment, offer fundamental knowledge while estimating geochemical fluxes from small mountainous rivers in Oceania region.