Optimal softening for force calculations in collisionless N-body simulations

In N-body simulations the force calculated between particles representing a given mass distribution is usually softened, to diminish the effect of graininess. In this paper we study the effect of such a smoothing, with the aim of finding an optimal value of the softening parameter. As already shown by Merritt (1996), for too small a softening the estimates of the forces will be too noisy, while for too large a softening the force estimates are systematically misrepresented. In between there is an optimal softening, for which the forces in the configuration approach best the true forces. The value of this optimal softening depends both on the mass distribution and on the number of particles used to represent it. For higher number of particles the optimal softening is smaller. More concentrated mass distributions necessitate smaller softening, but the softened forces are never as good an approximation of the true forces as for not centrally concentrated configurations. We give good estimates of the optimal softening for homogeneous spheres, Plummer spheres, and Dehnen spheres. We also give a rough estimate of this quantity for other mass distributions, based on the harmonic mean distance to the $k$th neighbour ($k$ = 1, .., 12), the mean being taken over all particles in the configuration. Comparing homogeneous Ferrers ellipsoids of different shapes we show that the axial ratios do not influence the value of the optimal softening. Finally we compare two different types of softening, a spline softening (Hernquist & Katz 1989) and a generalisation of the standard Plummer softening to higher values of the exponent. We find that the spline softening fares roughly as well as the higher powers of the power-law softening and both give a better representation of the forces than the standard Plummer softening.Comment: 16 pages Latex, 19 figures, accepted for publication in MNRAS, corrected typos, minor changes mainly in sec.

Comparison between OQPSK and DPSK bidirectional radio over fiber transmission systems

Radio over fiber is becoming an increasingly important technology for the wireless market since it introduces a higher data transmission rate and large bandwidth. In this paper, we have compared OQPSK and DPSK bidirectional radio over fiber ROF systems, where an offset quadrature phase shift keying (OQPSK) or differential phase shift keying (DPSK) signals are used for down-link and an on-off keying (OOK) signal re-modulated for up-link. Several measurements were performed including Bit Error Rate (BER) curves for uplink and downlink, RSOA gain curve and noise figure with the variation of input power and temperature for each system

Philanthropy, policy, and politics : power and influence of health care nonprofit interest groups on the implementation of health care policy

Indiana University-Purdue University Indianapolis (IUPUI)Nonprofit organizations that “speak for, act for, and look after the interests of their constituents when they interact with government are, by any definition of political science, interest groups.” Indiana’s recent implementation of the Healthy Indiana Plan 2.0 (HIP 2.0) under the Affordable Care Act (ACA) opened a window of opportunity to closely examine the role of nonprofits in shaping the implementation of health care policy. Existing literature on health and human service nonprofit organizations did not examine in depth the role and influence of nonprofits as interest groups in the implementation of public policy. This study examines a deeper research question that was not given adequate attention under existing studies with a special focus on the health care policy field: whose interest do nonprofit organizations advance when they attempt to influence the implementation of public policy? To answer this question, it is critical to understand why nonprofits engage in the public policy process (motivation and values), the policy actions that nonprofits make during the implementation of the policy (how?), and the method by which nonprofits address or mitigate conflicts and contradictions between organizational interest and constituents’ interest (whose interest do they advance?). The main contribution of this study is that it sheds light on the implementation of the largest extension of domestic social welfare policy since the “War on Poverty” using Robert Alford’s theory of interest groups to examine the role of nonprofit organizations during the implementation of HIP 2.0 in Indiana. Given the complexity of the policy process, this study utilizes a qualitative methods approach to complement existing quantitative findings. Finally, this study provides a deeper examination of the relationships between nonprofits as actors within a policy field, accounts for the complexity of the policy and political environment, analyzes whether or not dominant interest groups truly advance the interest of their constituents, and provides additional insights into how nonprofits mitigate and prioritize competing interests

Penta-Band Dielectric Loaded Folded Loop Antenna for Mobile Handset

A compact internal penta-band folded loop antenna for LTE1600/2600/WIMAX3. 5/WLAN2. 4/5.2 multiple mobile operations is proposed and investigated. The whole antenna structure is formed of a single folded meander loop pattern mount on the surfaces of a dielectric carrier with L-shape have a volume of 20 mm× 17mm× 5 mm, and ground plane of length 110mm is used. The size of the total structure is 110× 50× 5mm3. The compact structure makes it very suitable for today’s mobile phones applications. With 6 dB return loss, five operating frequency bands covering LTE/WLAN/WiMAX MHz can be achieved with our design. Also, the resonant characteristics of the antenna can be tuned by using various strip dimensions and also the dielectric material of the carrier. Moreover, simulated results exhibit that the proposed folded loop antenna features nearly good omnidirectional radiation patterns with proper gain. The design and optimizing of the performance of the proposed antenna are performed by using a high frequency structure simulator HFSS. Details of the various antenna parameters are presented and discussed in this paper

USING LINEAR MATRIX INEQUALITY METHOD TO DESIGN MINIMUM-LENGHT FINITE IMPULSE RESPONSE LOOP FILTERS IN FIXED WiMAX PLL

We designed Finite Impulse Response (FIR), digital filters by Semi-Definite Programming (SDP) using SeDuMi (self-dual minimization) toolbox software. The stability is assured using Linear Matrix Inequality (LMI) constraints. The minimum length FIR filter algorithm was used to proof that the order of the FIR filter, which was designed, is optimal for our design specifications. The proposed method gave better result with regard to all specifications of control signal, where we had the faster system and more stable than the other systems

ARMC 5 Variants and Risk of Hypertension in Blacks: MH- GRID Study.

Background We recently found that ARMC 5 variants may be associated with primary aldosteronism in blacks. We investigated a cohort from the MH - GRID (Minority Health Genomics and Translational Research Bio-Repository Database) and tested the association between ARMC 5 variants and blood pressure in black s. Methods and Results Whole exome sequencing data of 1377 black s were analyzed. Target single-variant and gene-based association analyses of hypertension were performed for ARMC 5, and replicated in a subset of 3015 individuals of African descent from the UK Biobank cohort. Sixteen rare variants were significantly associated with hypertension ( P=0.0402) in the gene-based (optimized sequenced kernel association test) analysis; the 16 and one other, rs116201073, together, showed a strong association ( P=0.0003) with blood pressure in this data set. The presence of the rs116201073 variant was associated with lower blood pressure. We then used human embryonic kidney 293 and adrenocortical H295R cells transfected with an ARMC 5 construct containing rs116201073 (c.*920T>C). The latter was common in both the discovery ( MH - GRID ) and replication ( UK Biobank) data and reached statistical significance ( P=0.044 [odds ratio, 0.7] and P=0.007 [odds ratio, 0.76], respectively). The allele carrying rs116201073 increased levels of ARMC5 mRNA , consistent with its protective effect in the epidemiological data. Conclusions ARMC 5 shows an association with hypertension in black s when rare variants within the gene are considered. We also identified a protective variant of the ARMC 5 gene with an effect on ARMC 5 expression confirmed in vitro. These results extend our previous report of ARMC 5's possible involvement in the determination of blood pressure in blacks

Biochar-based wastewater treatment to combat antimicrobial resistance

Antimicrobial resistance (AMR) is driven in part by environmental reservoirs of antimicrobial-resistant organisms and genes, as well as antimicrobials themselves, which drive resistance via selective pressure. According to the UN, 80% of all wastewater flows into the environment untreated. When wastewater is treated, treatment plants can act as hotspots of horizontal gene transfer from resistant to non-resistant organisms. There is therefore an urgent need to filter wastewater from sources rich in resistant bacteria and antimicrobials, like hospitals and pharmaceutical plants, before they reach environmental reservoirs where resistance can spread. Biochars produced from waste lignocellulosic biomass are ideal for this purpose, as they are highly adsorbent, affordable, and sustainable, with morphologies and surface chemistries that are tunable by choice of production conditions. Here, we link peak pyrolysis temperatures and alkaline pretreatment of walnut shell biochars to their filtration performance, showing these materials are suitable for in-line filtration of wastewater to combat AMR

The effect of caffeine ingestion in prevention of post-operative ileus after caesarean section: a randomized controlled trial

Background: Caesarian section (CS) has become more prevalent than the vaginal delivery in Egypt. Many complications could occur after an abdominal surgery. One of the commonest but yet serious complications is the postoperative ileus that can possibly be prevented by caffeine ingestion. The aim of the study is to assess the value of caffeine ingestion in promoting intestinal motility and prevention of postoperative ileus after CS.Methods: This is a randomized controlled trial that was conducted on 560 cases who were recruited from emergency unit and inpatient wards in Ain Shams University maternity hospital. The patients were divided into two groups where the intervention group received caffeinated coffee while the other group received decaffeinated coffee.Results: There was statistically significant difference between the two groups regarding the bowel function after CS (p <0.05). The intervention group had improved intestinal functions after the CS. Patients from the intervention group had audible intestinal sound sooner than the control group. In addition, they passed flatus and were able to tolerate food in less time.Conclusions: Consuming caffeinated coffee after CS contributes significantly to faster restoration of intestinal function. Coffee is a popular drink and can be used to decrease the incidence of postoperative ileus-related complications

Biochemical profile of heritage and modern apple cultivars and application of machine learning methods to predict usage, age, and harvest season

The present study represents the first major attempt to characterise the biochemical profile in different tissues of a large selection of apple cultivars sourced from the UK’s National Fruit Collection comprising dessert, ornamental, cider and culinary apples. Furthermore, advanced Machine Learning methods were applied with the objective to identify whether the phenolic and sugar composition of an apple cultivar could be used as a biomarker fingerprint to differentiate between heritage and mainstream commercial cultivars as well as govern the separation among primary usage groups and harvest season. Prediction accuracy > 90% was achieved with Random Forest for all three models. The results highlighted the extraordinary phytochemical potency and unique profile of some heritage, cider and ornamental apple cultivars, especially in comparison to more mainstream apple cultivars. Therefore, these findings could guide future cultivar selection on the basis of health-promoting phytochemical content

Symmetric 80 Gbps Next Generation Passive Optical Network Stage Two NG-PON2

In this research, a design of a symmetric 80 Gbps Passive Optical Network that meets the requirements of Next Generation Passive Optical Network Stage Two (NG-PON2) is proposed. According to The Full-Service Access Network (FSAN), The Time and Wave Length Division Multiplexing (TWDM) is chosen as the best solution to implement NG-PON2. TWDM network of NG-PON2 can be implemented in many wavelength plans to replace or co-exist with previous PON technologies. The proposed design was simulated taking into consideration the practical parameters of existing systems, the results shows that the system is reliable for implementation for 80 Gbps bitrate utilizing 8 pairs of wavelengths transmitted over 40 Km and distributed and received by 128 users with acceptable data rate