Scaling of load in communications networks

We show that the load at each node in a preferential attachment network scales as a power of the degree of the node. For a network whose degree distribution is p(k) ~ k^(-gamma), we show that the load is l(k) ~ k^eta with eta = gamma - 1, implying that the probability distribution for the load is p(l) ~ 1/l^2 independent of gamma. The results are obtained through scaling arguments supported by finite size scaling studies. They contradict earlier claims, but are in agreement with the exact solution for the special case of tree graphs. Results are also presented for real communications networks at the IP layer, using the latest available data. Our analysis of the data shows relatively poor power-law degree distributions as compared to the scaling of the load versus degree. This emphasizes the importance of the load in network analysis.Comment: 4 pages, 5 figure

Mixed sugar fermentation by Pichia stipitis, Sacharomyces cerevisiaea, and an isolated xylosefermenting Kluyveromyces marxianus and their cocultures

A yeast strain with higher rates and yields in the fermentation of glucose, mannose and galactose in semiaerobic conditions than Pichia stipitis and Sacharomyces cerevisiae and ethanol tolerance than P.stipitis, was isolated from sugarcane baggase from Iranian resources. This strain that can ferment xylose with lower rates and yields than P. stipitis is characterized as Kluyveromyces marxianus. Theability of K. marxianus to ferment mixed sugars comprised of 30 g/l glucose, 30 g/l xylose, 12 g/l mannose and 8 g/l galactose (total sugar 80 g/l), as a model of many hydrolysates, were compared to P.stipitis and S. cerevisiae and then a coculture of P. stipitis and S. cerevisiae was compared with a coculture of P. stipitis and K. marxianus. In mixed sugars fermentation with individual yeasts P. stipitis shows the highest yield (0.40 gg-1) and maximum ethanol (30.23 gl-1), but K. marxianus shows the highest Qpmax (1.09 gl-1h-1) and substrate utilization efficiency (E,>99%). P. stipiti and K. marxianus coculture shows the best results with high yield (0.42 gg-1) and maximum ethanol (31.87 gl-1), Qpmax (1.09 gl-1h-1) and substrate utilization efficiency (E,>99%). Because of the higher rates and yields of K. marxianus to ferment hexoses than P. stipitis and its higher ethanol tolerance, K. marxianus helps the P. stipitis to reach the concentration higher than 30 g/l ethanol concentration

The Large Scale Curvature of Networks

Understanding key structural properties of large scale networks are crucial for analyzing and optimizing their performance, and improving their reliability and security. Here we show that these networks possess a previously unnoticed feature, global curvature, which we argue has a major impact on core congestion: the load at the core of a network with N nodes scales as N^2 as compared to N^1.5 for a flat network. We substantiate this claim through analysis of a collection of real data networks across the globe as measured and documented by previous researchers.Comment: 4 pages, 5 figure

Influence of Ca²⁺ ions on the habit of KDP crystals

A few KDP (KH₂PO₄) and KDP:Ca²⁺ (CaCl₂) single crystals were grown based on the temperature reduction method. Investigations show that the presence of bivalent ions like Ca²⁺ could be a cause of retarded growth rate and induced crystalline lattice defects. Here the pure KDP crystals are compared with KDP:CaCl₂. Crystals of both types were also studied in aspect of other structural and optical properties

Cigarette butts abundance and association of mercury and lead along the Persian Gulf beach: an initial investigation.

The toxic metal contents of cigarette butts and distribution of cigarette butts have not been studied well in maritime environment. In the present study, cigarette butts distribution and the associations of Hg and Pb from cigarette butts were monitored along the Persian Gulf with 10 days interval sampling time. The number of cigarette butts, and Hg and Pb associations of butts were found to vary widely between 2 and 38 items per square meter, 2.5 and 86.32 ng/g cigarette butt (CB), as well as 650 and 8630 ng/g CB, respectively. Wilcoxon signed-rank test showed that there were no significant differences between the number of butts, and Hg and Pb contents of the butts at different sampling times. Considering amount of cigarette butts littered yearly, this study demonstrates that remarkable toxic metals of Hg and Pb may enter maritime environment each year and may introduce critical hazards to aquatic organisms, enter food chain, and finally human body. KEYWORDS: Bushehr; Cigarette butts; Lead; Mercury; Persian Gul

Inverse association between cigarette and water pipe smoking and hypertension in an elderly population in Iran: Bushehr elderly health programme.

The collected data in Bushehr Elderly Health (BEH) Program which had detailed the data on participants' smoking status and habits, was analysed to investigate the association between smoking of both water pipes and cigarettes and hypertension in an elderly population. Three thousand elderly men and women who participated in the baseline assessment of the BEH Program-a prospective population-based study being conducted in Bushehr, Iran-were selected randomly through a multistage, stratified cluster sampling method. Systolic and diastolic blood pressures were measured twice using a mercury sphygmomanometer, and researchers asked participants about medical history of hypertension as well as history of cigarette and water pipe smoking. Researchers used binary logistic regression models to assess the association of hypertension and smoking, and found an inverse, statistically significant association between current smoking and hypertension (odds ratio (OR)=0.50 (95% confidence interval (CI)=0.41, 0.60)). The association remained statistically significant after controlling for age, education and body mass index (OR=0.54 (95% CI=0.45, 0.66)). Findings were consistent for cigarette and water pipe smoking by sex (all ORs were inverse and statistically significant). Both cigarette and water pipe smoking were associated with reduced hypertension among older people, but the strength of association was different between men and women and also between cigarette and water pipe smoking. The reasons behind the association as well as the differences observed need to be investigated through more comprehensive, longitudinal studies

Impact of the climatic changes in the Pliocene-Pleistocene transition on Irano-Turanian species. The radiation of genus Jurinea (Compositae)

Altres ajuts: acords transformatius de la UABThe Irano-Turanian region is one of the world's richest floristic regions and the centre of diversity for numerous xerophytic plant lineages. However, we still have limited knowledge on the timing of evolution and biogeographic history of its flora, and potential drivers of diversification remain underexplored. To fill this knowledge gap, we focus on the Eurasian genus Jurinea (ca. 200 species), one of the largest plant radiations that diversified in the region. We applied a macroevolutionary integrative approach to explicitly test diversification hypotheses and investigate the relative roles of geography vs. ecology and niche conservatism vs. niche lability in speciation processes. To do so, we gathered a sample comprising 77% of total genus richness and obtained data about (1) its phylogenetic history, recovering 502 nuclear loci sequences; (2) growth forms; (3) ecological niche, compiling data of 21 variables for more than 2500 occurrences; and (4) paleoclimatic conditions, to estimate climatic stability. Our results revealed that climate was a key factor in the evolutionary dynamics of Jurinea. The main diversification and biogeographic events that occurred during past climate changes, which led to colder and drier conditions, are the following: (1) the origin of the genus (10.7 Ma); (2) long-distance dispersals from the Iranian Plateau to adjacent regions (∼7-4 Ma); and (3) the diversification shift during Pliocene-Pleistocene Transition (ca. 3 Ma), when net diversification rate almost doubled. Our results supported the pre-adaptation hypothesis, i.e., the evolutionary success of Jurinea was linked to the retention of the ancestral niche adapted to aridity. Interestingly, the paleoclimatic analyses revealed that in the Iranian Plateau long-term climatic stability favoured old-lineage persistence, resulting in current high species richness of semi-arid and cold adapted clades; whereas moderate climate oscillations stimulated allopatric diversification in the lineages distributed in the Circumboreal region. In contrast, growth form lability and high niche disparity among closely related species in the Central Asian clade suggest adaptive radiation to mountain habitats. In sum, the radiation of Jurinea is the result of both adaptive and non-adaptive processes influenced by climatic, orogenic and ecological factors

Quantum state preparation and macroscopic entanglement in gravitational-wave detectors

Long-baseline laser-interferometer gravitational-wave detectors are operating at a factor of 10 (in amplitude) above the standard quantum limit (SQL) within a broad frequency band. Such a low classical noise budget has already allowed the creation of a controlled 2.7 kg macroscopic oscillator with an effective eigenfrequency of 150 Hz and an occupation number of 200. This result, along with the prospect for further improvements, heralds the new possibility of experimentally probing macroscopic quantum mechanics (MQM) - quantum mechanical behavior of objects in the realm of everyday experience - using gravitational-wave detectors. In this paper, we provide the mathematical foundation for the first step of a MQM experiment: the preparation of a macroscopic test mass into a nearly minimum-Heisenberg-limited Gaussian quantum state, which is possible if the interferometer's classical noise beats the SQL in a broad frequency band. Our formalism, based on Wiener filtering, allows a straightforward conversion from the classical noise budget of a laser interferometer, in terms of noise spectra, into the strategy for quantum state preparation, and the quality of the prepared state. Using this formalism, we consider how Gaussian entanglement can be built among two macroscopic test masses, and the performance of the planned Advanced LIGO interferometers in quantum-state preparation

Searching for a Stochastic Background of Gravitational Waves with LIGO

The Laser Interferometer Gravitational-wave Observatory (LIGO) has performed the fourth science run, S4, with significantly improved interferometer sensitivities with respect to previous runs. Using data acquired during this science run, we place a limit on the amplitude of a stochastic background of gravitational waves. For a frequency independent spectrum, the new limit is $\Omega_{\rm GW} < 6.5 \times 10^{-5}$. This is currently the most sensitive result in the frequency range 51-150 Hz, with a factor of 13 improvement over the previous LIGO result. We discuss complementarity of the new result with other constraints on a stochastic background of gravitational waves, and we investigate implications of the new result for different models of this background.Comment: 37 pages, 16 figure

i Sexual function in breast cancer patients: a prospective study from Iran

Background: Sexual function in patients with breast cancer especially in younger patients is an important issue from clinical and psychosocial perspectives. This study aimed to assess sexual function among Iranian breast cancer patients. Methods: This was a prospective study of sexual function in breast cancer patients attending the Cancer Institute of Iran. Sexual function was assessed using the Female Sexual Function Index (FSFI) at two points in time: baseline (pre-treatment) and after completion of cancer treatment at follow-up visits (post-treatment). Pre- and posttreatment data were compared. In addition logistic regression analysis was performed to find out factors that contributing to post-treatment sexual dysfunction. Results: In all 277 breast cancer patients were approached. Of these, 231 patients (83%) were sexually active and data for 216 patients (93.5 % of sexually active patients) were available at pre-and post-treatment. Overall pre- and post-treatment sexual dysfunction was found to be 52 % and 84%, respectively indicating a significant deterioration in sexual function among breast cancer patients. The results obtained from multiple logistic regression analysis indicated that younger age [OR = 0.95, 95 % CI = 0.93-0.98; P = 0.04], receiving endocrine therapy [OR = 3.34, 95% CI = 1.37-7.91; P = 0.007] and poor sexual function at pre-treatment [OR = 12.3, 95 % CI = 3.93-39.0; P &lt; 0.0001