The Probability Game

ZHANG Yifeng is heading into a new chapter of her scientific career.The 39-year-old recently landed a coveted principal investigator （PI） job at the Institute of Neuroscience in Shanghai. There are only 27 PIs on staff,23 of whom are men and 4are women.It＇s a ratio that differs from when Zhang was in university, where gender ratios in her biology classes tended to be fifty-fifty. ＂Maybe even slightly more women than men,＂ she muses.

New Physical and Chemical Constants and Prospects of Its Use for the Explicit Expression of Thermodynamic Functions

Based on the analysis of the Boltzmann＇s distribution in an infinitely high temperature found degeneration of the thermodynamic system in a purely informational with independently of each particle on its energy level, thus providing them full visibility of and the ability to calculate the maximum entropy in the Boltzmann formula S∞ = R·InNA = 455.251 J/（mol.K）. This value, when expressed in terms of fundamental constants, is itself a physical and chemical constants and mole monatomic ideal gas is unsurpassed in any studied temperature range. For complex substances this limit increases in direct proportion to their atomic. The existence of two limits entropy change--lower, equal to zero according to the third law of thermodynamics, and the top, equal to S∞, makes possible the explicit expression of the temperature dependence of the entropy in the form of an exponentialS=S∞exp[-5030.31p 2/5 /（M3/5T）]（5/2）r e/s∞. rather than in the form of a logarithmic dependence of the infinite by the approximateformula Sakura-Tetrode with which this the dependence is almost identical in the studied temperature range （100-10,000 K）, but not absurd negative entropy in the extrapolation formula Sakura-Tetrode absolute zero to the region and especially in the area of T → ∞where it turns S →∞.

Weighted Hard Combination for Cooperative Spectrum Sensing in Cognitive Radio Networks

Weighted one bit hard combination for cooperative spectrum sensing is proposed in this paper. Two thresholds are adopted to divide the possible energy value into three weighted regions. If the energy value falls into the corresponding region,it will be judged as "1",no information or "0". When the probability of false alarm is constrained to be constant,the objective is to maximize the probability of detection. The optimization problem is simplified by separating the weight of the middle region into several intervals. Simulation results show that the sensing performance of the proposed scheme is much better than that of the traditional one bit hard combination scheme and almost the same as that of the equal gain combination(EGC) scheme. Moreover,compared with the traditional one bit hard combination,fewer average sensing bits are required to transmit to the data fusion center with the proposed method.

Secondary electron emission and photoemission from a negative electron affinity semiconductor with large mean escape depth of excited electrons

The formulae for parameters of a negative electron affinity semiconductor(NEAS)with large mean escape depth of secondary electrons A(NEASLD)are deduced.The methods for obtaining parameters such asλ,B,E_(pom)and the maximumδandδat 100.0 keV≥E_(po)≥1.0 keV of a NEASLD with the deduced formulae are presented(B is the probability that an internal secondary electron escapes into the vacuum upon reaching the emission surface of the emitter,δis the secondary electron yield,E_(po)is the incident energy of primary electrons and E_(pom)is the E_(po)corresponding to the maximumδ).The parameters obtained here are analyzed,and it can be concluded that several parameters of NEASLDs obtained by the methods presented here agree with those obtained by other authors.The relation between the secondary electron emission and photoemission from a NEAS with large mean escape depth of excited electrons is investigated,and it is concluded that the presented method of obtaining A is more accurate than that of obtaining the corresponding parameter for a NEAS with largeλ_(ph)(λ_(ph)being the mean escape depth of photoelectrons),and that the presented method of calculating B at E_(po)>10.0 keV is more widely applicable for obtaining the corresponding parameters for a NEAS with largeλ_(ph).

Analysis of connectivity in Ad-hoc network based on interference and fading channel

In Ad-hoc wireless network, connectivity is a fundamental issue which restricts the design of system protocol. Based on the theory of stochastic geometry, a connectivity model focused on signal-to-interference （SIR） ratio is set up in presence of Nakagami-m fading and interference. This paper derives a close formula of connectivity probability with interference and Nakagami-m fading which is never obtained in previous works. Two-dimension shot-noise theory in stochastic geometry for interference is well applied. The formula is verified by simulation. The results show that the connectivity is affected by the scatter of users, wireless propagation environment, interference and so on.