bluuebunny/crossref_metadata_2025 huggingface dataset:
Preliminary observations on the return of ovarian function among breast-feeding and post-partum non-breast-feeding women in a rural area of Mexico
Authors: Rivera Roberto , Ortiz Eva , Barrera Margarita , Kennedy Kathy , Bhiwandiwala Pouru
Published: October 2011

The relationship between the return of menstruation and ovulation and the pattern of breast-feeding was studied in a group of 29 women in a rural area of Mexico; eight non-breast-feeding post-partum women were also studied. The return of ovulation was assessed by weekly determinations of urinary pregnanediol. The number of suckling episodes and supplementary feeds was recorded. The cumulative probability of resumption of menses for the breast-feeders was 28% and 52% at 3 and 6 months, respectively, and for the non-breast-feeders was 75% and 88%. The cumulative probability of ovulation for the breast-feeders was 28%, 66%, 69% and 72% at 3, 6, 9 and 12 months, respectively, and for the non-breast-feeders was 50% and 100% at 3 and 6 months. The earlier the introduction of supplements the earlier the return of ovulation. The nonovulatory subjects maintained a higher frequency of suckling episodes than did the ovulatory subjects. The cumulative probability of pregnancy for the breast-feeders was 3%, 7%, 7% and 10% at 3, 6, 9 and 12 months, respectively, and for the non-breast-feeders was 13%, 38% and 50% at 3, 6 and 9 months.
Breast-feeding and fertility among Philippine women: trends, mechanisms and impact
Authors: Zablan Zelda C.
Published: October 2011

In pre-transitional societies, contraceptive practice is usually low or absent and prolonged breast-feeding has been identified as the major factor in keeping marital fertility levels below the biological maximum (Bongaarts, 1978), so that the length of birth intervals is the strongest determinant of completed family size.

In transitional societies there is accumulating evidence that, with increasing modernization, the percentage of women who initiate breast-feeding and the duration of breast-feeding are declining (Jelliffe & Jelliffe, 1972; McCann et al., 1981; Rosa, 1976). Shorter durations of breast-feeding are observed for women who are more educated, belong to the upper socioeconomic class and live in urban areas (Jain & Sun, 1972; Lesthaeghe & Page, 1980).
Investing in health: value for money—with special reference to West Africa
Authors: Azefor Michael N. A.
Published: October 2011

Recent economic crises have severely affected national and international efforts to reduce the high morbidity and mortality in developing countries. The repercussions of these crises are manifest in declining living standards, increasing poverty, malnutrition, ill health and death. Depressed commodity prices, the oil crisis of the late 1970s, and the ensuing balance of payment problems have weakened most governments' efforts to halt and eventually reverse the economic decline. In sub-Saharan Africa the effects of these crises have combined with an ever-increasing population to render ineffective the limited investments in health care.
Maternal mortality: levels, causes and promising interventions
Authors: Kwast Barbara E.
Published: October 2011

About two-thirds of the world's population live in areas where registration of vital statistics is unsatisfactory (Tietze, 1977), and in many countries such statistics from rural areas are unavailable or grossly underestimated (WHO, 1971). Most of the women who die in pregnancy and childbirth are poor and live in remote areas or city slums. Their deaths are accorded little importance and fail to enter registers.
Reduction in neonatal mortality by simple interventions
Authors: Daga S. R.
Published: October 2011

Newborn infants are among those which generate the highest health care costs. For instance, the cost of hospital care until discharge was assessed at US $ 14,200 (Boyle et al., 1983) for babies weighing 1000–1499g at birth. The average hospital stay for a baby weighing less than 1500g at birth in 1981 was 100 days at an average daily cost of US$ 898 (Stahlman, 1984). Achievements in neonatal survival, especially of extremely low birth weight babies, have necessitated frequent revision of the definition of viability. However, modern neonatal intensive care cannot be regarded as appropriate for developing countries as it cannot be made accessible to all at an affordable cost.
The dynamics of contraceptive use: an overview
Authors: Tsui Amy Ong
Published: October 2011

For nearly three decades men and women have increasingly gained the opportunity to control their childbearing with modern contraceptive technologies. In the early 1960s when oral hormonal contraceptives and intrauterine devices first became publicly available in the United States and Europe, the total fertility rate (TFR) in industrialized countries was about 2·7 implying that two-thirds of childbearing couples, some 87 million, were practising contraception. By comparison, in the developing areas, the TFR was 6·1 and only 18% (60 million couples) were contraceptive users. Thirty years later, estimating for 1990, the number of eligible couples practising contraception in the more developed countries (MDCs) is expected to have increased by half, while in the less developed countries (LDCs) the increase is likely to be six times, suggesting as many as 344 million users. Another way to demonstrate the significance of this trend is with a different statistic—that the level of contraceptive use in LDCs in 1990 will exceed half of all couples of childbearing age and be only ten percentage points below the MDC level of 25–30 years ago.
Determinants of contraceptive use dynamics: research needs on decision and choice
Authors: Mundigo Axel I. , Phillips James F. , Chamratrithirong Aphichat
Published: October 2011

Because of the importance of contraceptive behaviour in most societies today a better understanding is needed of the social and behavioural factors affecting contraceptive decisions and choices of individuals and couples. This paper examines the need for longitudinal, theoretically-based studies of contraceptive use dynamics, including the timing, duration and interaction of reproductive events which may be more important than contraceptive technology in the social, cultural and economic context of fertility control. New research methods and appropriate analysis of data are relevant. Consideration of the social context is essential for the formulation and implementation of effective policies relating to the provision of contraceptive services.
Comparative study of efficacy of graft placement with and without anterior tagging in type one tympanoplasty for mucosal-type chronic otitis media
Authors: Hosamani P , Ananth L , Medikeri S B
Published: October 2011

Objectives:

To assess the efficacy of anterior tagging of graft material with respect to graft uptake and hearing results, in type I tympanoplasty.

Study design:

Prospective, randomised, cohort study.

Methods:

Sixty patients with chronic otitis media of the mucosal type, with pars tensa perforations, were included in the study. Patients were randomly allocated to two groups: group one underwent type one tympanoplasty with anterior tagging, while group two underwent type one tympanoplasty without anterior tagging. Follow up included evaluation of graft uptake and hearing improvement.

Results:

There were 33 patients in group one and 27 patients in group two. The overall incidence of successful graft uptake was 96.96 per cent in group one and 81.5 per cent in group two. Closure of central and posterior perforations was successful in 100 per cent of both groups. Closure of anterior and subtotal perforations was successful in 95.45 per cent of group one and 54.54 per cent of group two.

Conclusion:

Type one tympanoplasty with anterior tagging of graft material is a suitable technique for anterior and subtotal perforations.
Visual loss following head and neck surgery
Authors: Crockett A J B , Trinidade A , Kothari P , Barnes J
Published: October 2011

Introduction:

Non-arteritic ischaemic optic neuritis is a known post-operative complication of ophthalmological and maxillofacial surgery, but has not been widely described as a potential consequence of head and neck surgery.

Aim:

To highlight non-arteritic ischaemic optic neuritis as a potential risk in patients undergoing head and neck surgery.

Subject and method:

Case report of a 60-year-old man undergoing total laryngectomy and bilateral neck dissection for laryngeal squamous cell carcinoma.

Result:

On day 14 post-operatively, the patient suffered substantial oral bleeding secondary to an internal jugulo-neopharyngeal fistula. Following emergency haemostatic measures, the patient was immediately aware of visual disturbances. The ophthalmologists concluded that these were due to non-arteritic ischaemic optic neuritis, caused by acute hypoxaemia secondary to substantial blood loss.

Conclusion:

The prognosis of non-arteritic ischaemic optic neuritis is poor. Thus, it is crucial that otolaryngologists are aware of this complication of head and neck surgery, as immediate diagnosis and treatment can help prevent worsening visual loss.
Draping for neck surgery requiring endotracheal tube manipulation
Authors: Dalton C L , Clamp P J , Porter G C
Published: October 2011

During airway surgery, the anaesthetist may be required to manipulate or withdraw the endotracheal tube. Traditional surgical head drapes often make access to the tube difficult, therefore limiting control of the airway and risking de-sterilisation of the surgical field. We report a new method of draping for major neck operations that permits easy access to the endotracheal tube while maintaining sterility of the operative field.
VACCINIUM NAGAMASU (ERICACEAE), A NEW SPECIES (SECT. BRACTEATA) FROM SUMATRA, INDONESIA
Authors: Argent G.
Published: October 2011

A new species of Vaccinium section Bracteata (Ericaceae), Vaccinium nagamasu Argent, presently known only from the type specimen from around the summit of Mt. Rasam c.10 km south of Lake Diatas, West Sumatra, Indonesia, is described. Its distinctive characters are discussed and comments made on the differences between this and other related species.
Trees of Panama and Costa Rica . R. Condit, R. Pe ́ rez & N. Daguerre.
Authors: Haston Elspeth
Published: October 2011

..
Experiencing Psychological Processes and Understanding Their Implications
Authors: Transue John
Published: October 2011

This article presents three classroom demonstrations designed to help instructors who would like to include some political psychology in their classes. All three demonstrations involve student participation and give the students direct experience with psychological processes relevant to political science. Specifically, I describe how I present the Stroop task, a priming task, and Tversky and Kahneman's Asian disease experiment in my own teaching. For each of the demonstrations, I give practical advice for classroom use, a short description of the psychological processes the demonstration illustrates, and a brief discussion of how those processes have been applied in political science.
Forum
Authors: Erickson Kenneth Paul , Markovitz Irving Leonard
Published: October 2011

The editors of Comparative Politics appreciated the article by Stephen Yoder and Brittany Bramlett on journal transparency both for the wealth of data it contained and for the authors' efforts to identify professional dilemmas that can arise from a “lack of transparency” in the procedures of many political science journals. In surveying the editors of the top thirty political science journals, Yoder and Bramlett found that most journals do not publicly release submission and decision data, which they suggest may owe in part to poor recordkeeping due to staff shortages, rapid staff turnover, and the migration of journals from one sponsoring institution to another.
Annual Meeting
Authors: West Lauren
Published: October 2011

For the first time in its history, the American Political Science Association held its annual meeting in Seattle, Washington, bringing together more than 6,000 political scientists from all over the world for a variety of programmatic, networking, and social events. From September 1 to September 4, scholars gathered in the beautiful Pacific Northwest to explore an exciting program focused on the theme The Politics of Rights. The 2011 Annual Meeting Program Chairs Frances Hagopian, Harvard University, and Bonnie Honig, Northwestern University, developed a theme that asked “the discipline bring its empirical and normative lenses to reflect on the domestic, comparative, and international dimensions of the complex politics of rights.”
Spread ofSalmonella entericain the body during systemic infection: unravelling host and pathogen determinants
Authors: Mastroeni Pietro , Grant Andrew J.
Published: October 2011

Salmonella entericacauses a range of life-threatening diseases in humans and animals worldwide. Current treatments forS. entericainfections are not sufficiently effective, and there is a need to develop new vaccines and therapeutics. An understanding of howS. entericaspreads in tissues has very important implications for targeting bacteria with vaccine-induced immune responses and antimicrobial drugs. Development of new control strategies would benefit from a more sophisticated evaluation of bacterial location, spatiotemporal patterns of spread and distribution in the tissues, and sites of microbial persistence. We review here recent studies ofS. entericaserovar Typhimurium (S. Typhimurium) infections in mice, an established model of systemic typhoid fever in humans, which suggest that continuous bacterial spread to new infection foci and host phagocytes is an essential trait in the virulence ofS. entericaduring systemic infections. We further highlight how infections within host tissues are truly heterogeneous processes despite the fact that they are caused by the expansion of a genetically homogeneous microbial population. We conclude by discussing how understanding the within-host quantitative, spatial and temporal dynamics ofS. entericainfections might aid the development of novel targeted preventative measures and drug regimens.
The YAP Prolog system
Authors: COSTA VÍTOR SANTOS , ROCHA RICARDO , DAMAS LUÍS
Published: October 2011

Yet Another Prolog (YAP) is a Prolog system originally developed in the mid-eighties and that has been under almost constant development since then. This paper presents the general structure and design of the YAP system, focusing on three important contributions to the Logic Programming community. First, it describes the main techniques used in YAP to achieve an efficient Prolog engine. Second, most Logic Programming systems have a rather limited indexing algorithm. YAP contributes to this area by providing a dynamic indexing mechanism, or just-in-time indexer. Third, a important contribution of the YAP system has been the integration of both or-parallelism and tabling in a single Logic Programming system.
Multilayer detection and classification of specular and nonspecular meteor trails
Authors: Zhao Siming , Urbina Julio , Dyrud Lars , Seal Ryan
Published: October 2011

Meteor radar data are continuously collected by different radar systems that operate throughout the year. Analyzing this fast growing, large data set requires efficient and reliable detection routines. Currently most meteor echo routines search for underdense meteor trails, often discarding overdense and nonspecular meteor trails. This is because their main purpose is the study of mesospheric winds. But the study of meteor flux requires the unique identification of each type of meteor reflections. In this paper, a multilayer radar detection and classification algorithm is proposed to correctly identify multiple types of meteor trail reflections. The process consists of two steps. The first step is based on the time‐frequency waveform detector. In this step, we start by selecting low signal‐to‐noise ratio (SNR) values in order to detect all types of radar echoes; however, a high probability offalse alarm is often produced. In the second step, several features from the detected echoes in step one are extracted and a support vector machine (SVM) classifier is constructed to further classify these echoes. The algorithm was tested using data collected from a 50‐MHz radar stationed near Salinas, Puerto Rico, on April 5, 1998. A total of 270 detected echoes were labeled as underdense, overdense, nonspecular, other ionospheric echoes, and noise. We used 50% of the labeled echoes as training samples and divided the rest 50% testing samples as 10 subsets for testing. This technique successfully classified about 85% of the testing samples. Details concerning implementation, feature extraction, and data visualization are presented and discussed.
Assessing the complex sponge microbiota: core, variable and species-specific bacterial communities in marine sponges
Authors: Schmitt Susanne , Tsai Peter , Bell James , Fromont Jane , Ilan Micha , Lindquist Niels , Perez Thierry , Rodrigo Allen , Schupp Peter J , Vacelet Jean , Webster Nicole , Hentschel Ute , Taylor Michael W
Published: October 2011

Marine sponges are well known for their associations with highly diverse, yet very specific and often highly similar microbiota. The aim of this study was to identify potential bacterial sub-populations in relation to sponge phylogeny and sampling sites and to define the core bacterial community. 16S ribosomal RNA gene amplicon pyrosequencing was applied to 32 sponge species from eight locations around the world's oceans, thereby generating 2567 operational taxonomic units (OTUs at the 97% sequence similarity level) in total and up to 364 different OTUs per sponge species. The taxonomic richness detected in this study comprised 25 bacterial phyla with Proteobacteria, Chloroflexi and Poribacteria being most diverse in sponges. Among these phyla were nine candidate phyla, six of them found for the first time in sponges. Similarity comparison of bacterial communities revealed no correlation with host phylogeny but a tropical sub-population in that tropical sponges have more similar bacterial communities to each other than to subtropical sponges. A minimal core bacterial community consisting of very few OTUs (97%, 95% and 90%) was found. These microbes have a global distribution and are probably acquired via environmental transmission. In contrast, a large species-specific bacterial community was detected, which is represented by OTUs present in only a single sponge species. The species-specific bacterial community is probably mainly vertically transmitted. It is proposed that different sponges contain different bacterial species, however, these bacteria are still closely related to each other explaining the observed similarity of bacterial communities in sponges in this and previous studies. This global analysis represents the most comprehensive study of bacterial symbionts in sponges to date and provides novel insights into the complex structure of these unique associations.
Obesity Paradox in Amputation Risk Among Nonelderly Diabetic Men
Authors: Sohn Min‐Woong , Budiman‐Mak Elly , Oh Elissa H. , Park Michael S. , Stuck Rodney M. , Stone Neil J. , Pearce William B.
Published: October 2011

The association between BMI and amputation risk is not currently well known. We used data for a cohort of diabetic patients treated in the US Department of Veterans Affairs Healthcare System in 2003. Men aged <65 years at the end of follow‐up were examined for their amputation risk and amputation‐free survival during the next 5 years (2004–2008). Compared to overweight individuals (BMI 25–29.9 kg/m2), the risks of amputation and treatment failure (amputation or death) were higher for patients with BMI <25 kg/m2 and were lower for those with BMI ≥30 kg/m2. Individuals with BMI ≥40 kg/m2 were only half as likely to experience any (hazard ratios (HR) = 0.49; 95% confidence interval (CI), 0.30–0.80) and major amputations (HR = 0.53; 95% CI, 0.39–0.73) during follow‐up as overweight individuals. While the amputation risk continued to decrease for higher BMI, amputation‐free survival showed a slight upturn at BMI >40 kg/m2. The association between obesity and amputation risk in our data shows a pattern consistent with “obesity paradox” observed in many health conditions. More research is needed to better understand pathophysiological mechanisms that may explain the paradoxical association between obesity and lower‐extremity amputation (LEA) risk.
Obese Children Have Higher Arterial Elasticity Without a Difference in Endothelial Function: The Role of Body Composition
Authors: Tryggestad Jeanie B. , Thompson David M. , Copeland Kenneth C. , Short Kevin R.
Published: October 2011

The childhood obesity epidemic is expected to increase cardiovascular disease risk, but the impact of obesity on vascular function in children is not fully understood. The purpose of this study was to determine the effect of obesity and maturation on vascular function in normal weight (BMI: 25–75 percentile) and obese (BMI: ≥95 percentile) children ages 8–18 years old. Large and small artery elasticity (LAEI and SAEI, respectively), measured by diastolic radial pulsewave contour analysis, and reactive hyperemia index (RHI), measured by peripheral arterial tonometry, were obtained, along with anthropometric and biochemical outcomes, in 61 normal weight and 62 obese children. SAEI and LAEI increased with age and were 30% and 18% higher, respectively, in obese children (P < 0.01). In contrast, reactive hyperemia increased with age in the normal weight group but did not differ between groups. Multivariate modeling was used to select variables that explained differences in vascular outcomes. The best model for LAEI in normal weight children was height alone (r2 = 0.49), whereas for obese children the best model included height + fat mass (r2 = 0.40). For SAEI, there were no significant models for normal weight children, but for obese children the best model included lean mass + fat mass (r2 = 0.36). Obese children had greater lean and fat mass, and more advanced Tanner stages than their normal weight peers. The increased elasticity observed in obese children appears to reflect accelerated growth and maturation without affecting vascular reactivity measured by reactive hyperemia. Longitudinal follow up will be essential in determining effects on future vascular disease risk.
Sleep and Eating Behavior in Adults at Risk for Type 2 Diabetes
Authors: Kilkus Jennifer M. , Booth John N. , Bromley Lindsay E. , Darukhanavala Amy P. , Imperial Jacqueline G. , Penev Plamen D.
Published: October 2011

Insufficient quantity and quality of sleep may modulate eating behavior, everyday physical activity, overall energy balance, and individual risk of obesity and type 2 diabetes. We examined the association of habitual sleep quantity and quality with the self‐reported pattern of eating behavior in 53 healthy urban adults with parental history of type 2 diabetes (30 F/23 M; mean (s.d.) age: 27 (4) years; BMI: 23.9 (2.3) kg/m2) while taking into consideration the amount of their everyday physical activity. Participants completed 13 (3) days of sleep and physical activity monitoring by wrist actigraphy and waist accelerometry while following their usual lifestyle at home. Overnight laboratory polysomnography was used to screen for sleep disorders. Subjective sleep quality was measured with the Pittsburgh Sleep Quality Index. Eating behavior was assessed using the original 51‐item and the revised 18‐item version of the Three‐Factor Eating Questionnaire including measures of cognitive restraint, disinhibition, hunger, and uncontrolled and emotional eating. In multivariable regression analyses adjusted for age, BMI, gender, race/ethnicity, level of education, habitual sleep time measured by wrist actigraphy and physical activity measured by waist accelerometry, lower subjective sleep quality was associated with increased hunger, more disinhibited, uncontrolled and emotional eating, and higher cognitive restraint. There was no significant association between the amount of sleep measured by wrist actigraphy and any of these eating behavior factors. Our findings indicate that small decrements in self‐reported sleep quality can be a sensitive indicator for the presence of potentially problematic eating patterns in healthy urban adults with familial risk for type 2 diabetes.
Detection of Rho GEF and GAP activity through a sensitive split luciferase assay system
Authors: Anderson Erik L. , Hamann Michael J.
Published: October 2011

Rho GTPases regulate the assembly of cellular actin structures and are activated by GEFs (guanine-nucleotide-exchange factors) and rendered inactive by GAPs (GTPase-activating proteins). Using the Rho GTPases Cdc42, Rac1 and RhoA, and the GTPase-binding portions of the effector proteins p21-activated kinase and Rhophilin1, we have developed split luciferase assays for detecting both GEF and GAP regulation of these GTPases. The system relies on purifying split luciferase fusion proteins of the GTPases and effectors from bacteria, and our results show that the assays replicate GEF and GAP specificities at nanomolar concentrations for several previously characterized Rho family GEFs (Dbl, Vav2, Trio and Asef) and GAPs [p190, Cdc42 GAP and PTPL1-associated RhoGAP]. The assay detected activities associated with purified recombinant GEFs and GAPs, cell lysates expressing exogenous proteins, and immunoprecipitates of endogenous Vav1 and p190. The results demonstrate that the split luciferase system provides an effective sensitive alternative to radioactivity-based assays for detecting GTPase regulatory protein activities and is adaptable to a variety of assay conditions.
Destabilization of Ag nanoislands on Ag(100) by adsorbed sulfur
Authors: Shen Mingmin , Russell Selena M. , Liu Da-Jiang , Thiel Patricia A.
Published: October 2011

Sulfur accelerates coarsening of Ag nanoislands on Ag(100) at 300 K, and this effect is enhanced with increasing sulfur coverage over a range spanning a few hundredths of a monolayer, to nearly 0.25 monolayers. We propose that acceleration of coarsening in this system is tied to the formation of AgS2 clusters primarily at step edges. These clusters can transport Ag more efficiently than can Ag adatoms (due to a lower diffusion barrier and comparable formation energy). The mobility of isolated sulfur on Ag(100) is very low so that formation of the complex is kinetically limited at low sulfur coverages, and thus enhancement is minimal. However, higher sulfur coverages force the population of sites adjacent to step edges, so that formation of the cluster is no longer limited by diffusion of sulfur across terraces. Sulfur exerts a much weaker effect on the rate of coarsening on Ag(100) than it does on Ag(111). This is consistent with theory, which shows that the difference between the total energy barrier for coarsening with and without sulfur is also much smaller on Ag(100) than on Ag(111).
Direct comparison of domain wall behavior in permalloy nanowires patterned by electron beam lithography and focused ion beam milling
Authors: Basith M. A. , McVitie S. , McGrouther D. , Chapman J. N. , Weaver J. M. R.
Published: October 2011

Nominally identical permalloy nanowires, with widths down to 150 nm, were fabricated onto a single-electron transparent Si3N4 membrane using electron beam lithography (EBL) and focused ion beam (FIB) milling. Transmission electron microscopy (TEM) experiments were performed to compare the nanostructures produced by these two techniques in what we believe is the first direct comparison of fabrication techniques for nominally identical nanowires. Both EBL and FIB methods produced high quality structures with edge roughness being of the order of the mean grain size 5–10 nm observed in the continuous films. However, significant grain growth was observed along the edges of the FIB patterned nanowires. Lorentz TEM in situ imaging was carried out to compare the magnetic behavior of the domain walls in the patterned nanowires with anti-notches present to pin domain walls. The overall process of domain wall pinning and depinning at the anti-notches showed consistent behavior between nanowires fabricated by the two methods with the FIB structures having slightly lower characteristic fields compared to the EBL wires. However, a significant difference was observed in the formation of a vortex structure inside the anti-notches of the EBL nanowires after depinning of the domain walls. No vortex structure was seen inside the anti-notches of the FIB patterned nanowires. Results from micromagnetic simulations suggest that the vortex structure inside the anti-notch can be suppressed if the saturation magnetization (Ms) is reduced along the nanowire edges. A reduction of Ms along the wire edges may also be responsible for a decrease in the domain wall depinning fields. Whereas the two fabrication methods show that well-defined structures can be produced for the dimensions considered here, the differences in the magnetic behavior for nominally identical structures may be an issue if such structures are to be used as conduits for domain walls in potential memory and logic applications.
A weakened cascade model for turbulence in astrophysical plasmas
Authors: Howes G. G. , TenBarge J. M. , Dorland W.
Published: October 2011

A refined cascade model for kinetic turbulence in weakly collisional astrophysical plasmas is presented that includes both the transition between weak and strong turbulence and the effect of nonlocal interactions on the nonlinear transfer of energy. The model describes the transition between weak and strong MHD turbulence and the complementary transition from strong kinetic Alfvén wave (KAW) turbulence to weak dissipating KAW turbulence, a new regime of weak turbulence in which the effects of shearing by large scale motions and kinetic dissipation play an important role. The inclusion of the effect of nonlocal motions on the nonlinear energy cascade rate in the dissipation range, specifically the shearing by large-scale motions, is proposed to explain the nearly power-law energy spectra observed in the dissipation range of both kinetic numerical simulations and solar wind observations.
Adaptive tuning of feedback gain in time-delayed feedback control
Authors: Lehnert J. , Hövel P. , Flunkert V. , Guzenko P. Yu. , Fradkov A. L. , Schöll E.
Published: October 2011

We demonstrate that time-delayed feedback control can be improved by adaptively tuning the feedback gain. This adaptive controller is applied to the stabilization of an unstable fixed point and an unstable periodic orbit embedded in a chaotic attractor. The adaptation algorithm is constructed using the speed-gradient method of control theory. Our computer simulations show that the adaptation algorithm can find an appropriate value of the feedback gain for single and multiple delays. Furthermore, we show that our method is robust to noise and different initial conditions.
Barriers in the transition to global chaos in collisionless magnetic reconnection. I. Ridges of the finite time Lyapunov exponent field
Authors: Borgogno D. , Grasso D. , Pegoraro F. , Schep T. J.
Published: October 2011

The transitional phase from local to global chaos in the magnetic field of a reconnecting current layer is investigated. Regions where the magnetic field is stochastic exist next to regions where the field is more regular. In regions between stochastic layers and between a stochastic layer and an island structure, the field of the finite time Lyapunov exponent (FTLE) shows a structure with ridges. These ridges, which are special gradient lines that are transverse to the direction of minimum curvature of this field, are approximate Lagrangian coherent structures (LCS) that act as barriers for the transport of field lines.
Measurement sensitivity improvement in tapping-mode atomic force microscopy through bi-harmonic drive signal
Authors: Loganathan Muthukumaran , Kodandarama Santosh R. , Bristow Douglas A.
Published: October 2011

This article presents a novel method to improve the measurement sensitivity and reduce impact forces in tapping-mode atomic force microscopy by reshaping the tip trajectory. A tapping drive signal composed of two harmonics is used to generate an oscillating trajectory with a broader valley compared to the typical sinusoidal trajectory. The wide broad valley reduces the velocity of the tip in the vicinity of the sample and allots a greater portion of each period in the vicinity of the sample. Numerical simulations show that this results in decreased impact force and increased sensitivity of the cantilever oscillation to changes in tip-sample offset. Experimental results demonstrate an increase in image sharpness and decrease in tip wear using the bi-harmonic driving signal.
Note: Compact high voltage pulse transformer made using a capacitor bank assembled in the shape of primary
Authors: Shukla Rohit , Banerjee Partha , Sharma Surender K. , Das Rashmita , Deb Pankaj , Prabaharan T. , Das Basanta , Adhikary Biswajit , Verma Rishi , Shyam Anurag
Published: October 2011

The experimental results of an air-core pulse transformer are presented, which is very compact (<10 Kg in weight) and is primed by a capacitor bank that is fabricated in such a way that the capacitor bank with its switch takes the shape of single-turn rectangular shaped primary of the transformer. A high voltage capacitor assembly (pulse-forming-line capacitor, PFL) of 5.1 nF is connected with the secondary of transformer. The transformer output voltage is 160 kV in its second peak appearing in less than 2 μS from the beginning of the capacitor discharge. The primary capacitor bank can be charged up to a maximum of 18 kV, with the voltage delivery of 360 kV in similar capacitive loads.
Mode conversion by symmetry breaking of propagating spin waves
Authors: Clausen P. , Vogt K. , Schultheiss H. , Schäfer S. , Obry B. , Wolf G. , Pirro P. , Leven B. , Hillebrands B.
Published: October 2011

We study spin-wave transport in a microstructured Ni81Fe19 waveguide exhibiting broken translational symmetry. We observe the conversion of a beam profile composed of symmetric spin-wave width modes with odd numbers of antinodes n = 1, 3,… into a mixed set of symmetric and asymmetric modes. Due to the spatial homogeneity of the exciting field along the used microstrip antenna, quantized spin-wave modes with an even number n of antinodes across the stripe’s width cannot be directly excited. We show that a break in translational symmetry may result in a partial conversion of even spin-wave waveguide modes.
Color of TiN and ZrN from first-principles calculations
Authors: Kim Jinwoong , Jhi Seung-Hoon , Ryeol Lee Kwang
Published: October 2011

The optical properties, especially the colors, of transition metal nitrides (TiN and ZrN) are studied using first-principles method. Full ab-initio procedure of color-prediction including plasma frequency is presented. The dielectric functions and reflectivity of the compounds are calculated including both intraband and interband transitions. The color of the compounds is then produced by calculating the red-green-blue color codes through the convolution of color matching functions and the calculated reflectivity. Calculated colors and screened plasma frequency for the materials are in good agreement with measurement. The color variation due to chemical doping is also studied within the rigid band approximation.
Accurate quantum mechanical study of the Renner-Teller effect in the singlet CH2
Authors: Zhang Zhijun , Ma Haitao , Bian Wensheng
Published: October 2011

The Renner-Teller (RT) effect between the two low-lying electronic states of singlet CH2, $\tilde a^1 A_1$ã1A1 and $\tilde b^1 B_1$b̃1B1, is studied using the multi-configuration time-dependent Hartree method with complete treatment of the RT terms. The RT terms, which are the matrix elements of the electronic orbital angular momentum operators, are calculated with ab initio methods and fitted to analytical functions. The ro-vibronic energy levels with complete treatment and constant approximation of the RT terms are calculated and compared. The influences of the geometry dependence of the RT terms on the ro-vibronic energy levels are discussed. The differences of the variation trends and influences of the RT terms between CH2 and NH2 are explored. In particular, as the molecule bends from linearity, the curve of the RT term ($\langle {\tilde a^1 A_1 } |\hat L_z^2 | {\tilde a^1 A_1 } \rangle$⟨ã1A1|L̂z2|ã1A1⟩) first goes down to reach a minimum and then goes up leading to decreased zero point energy and bending energy levels for the lower state of CH2 in contrast to the case of NH2.
Independent electrical tuning of separated quantum dots in coupled photonic crystal cavities
Authors: Thon S. M. , Kim H. , Bonato C. , Gudat J. , Hagemeier J. , Petroff P. M. , Bouwmeester D.
Published: October 2011

Systems of photonic crystal cavities coupled to quantum dots are a promising architecture for quantum networking and quantum simulators. The ability to independently tune the frequencies of laterally separated quantum dots is a crucial component of such a scheme. Here, we demonstrate the independent tuning of laterally separated quantum dots in photonic crystal cavities coupled by in-plane waveguides by implanting lines of protons which serve to electrically isolate different sections of a diode structure.
Helium corona-assisted air discharge
Authors: Jiang Nan , Gao Lei , Ji Ailing , Cao Zexian
Published: October 2011

Operation of atmospheric discharge of electronegative gases including air at low voltages yet without consuming any inert gas will enormously promote the application of non-thermal plasmas. By taking advantage of the low onset voltage for helium corona, air discharge was successfully launched at much reduced voltages with a needle-plate system partly contained in a helium-filled glass bulb—for a needle-plate distance of 12 mm, 1.0 kV suffices. Ultraviolet emission from helium corona facilitates the discharging of air, and the discharge current manifests distinct features such as relatively broad Trichel pulses in both half periods. This design allows safe and economic implementation of atmospheric discharge of electronegative gases, which will find a broad palette of applications in surface modification, plasma medicine and gas treatment, etc.
Field-effect control of electrokinetic ion transport in a nanofluidic channel
Authors: Pal Singh Kunwar , Kumari Kusum , Kumar Manoj
Published: October 2011

We have simulated field-effect control of electrokinetic ion transport in a fluidic nanochannel with negative surface charge on its walls. A third electrode, known as a gate, is used on the channel walls to modulate its zeta-potential and ion concentration inside it. The ion current is controlled by the gate-induced ion enrichment/depletion and changes of electric field in the vicinity of the gate. There are four regions of ion current control by gate at low electrolyte concentration: decreasing electric field, cation enrichment, quasi-neutrality, and cation depletion as the gate potential changes from negative values to positive values. The effectiveness of ion current control by gate decreases with increasing surface charge density due to change in zeta-potential and overall electro-neutrality condition. The ion current through the nanochannel is also affected by electrolyte concentration. The proposed nanofluidic device could have broad applications in integrated nanofluidic circuits for manipulation of ions, biomolecules in sub-femtoliter volumes, ion separation, and biofluidic circuits.
Efficient laser-proton acceleration from an insulating foil with an attached small metal disk
Authors: Otani Kazuto , Tokita Shigeki , Nishoji Toshihiko , Inoue Shunsuke , Hashida Masaki , Sakabe Shuji
Published: October 2011

Efficient proton acceleration by the interaction of an intense femtosecond laser pulse with a solid foil has been demonstrated. An aluminum coating (thickness: 0.2 μm) on a polyethylene (PE) foil was irradiated at 2 × 1018 W/cm2 intensity. The protons from the aluminum-disk (diameter: 150 μm to 15 mm) foil were accelerated to much higher energy in comparison with conventional targets such as PE and aluminum-coated PE foils. The fast electron signal along the foil surface was significantly higher from the aluminum-coated PE foil. The laser-proton acceleration appeared to be affected to the size of surrounding conductive material.
Raman spectroscopy and microscopy based on mechanical force detection
Authors: Rajapaksa I. , Kumar Wickramasinghe H.
Published: October 2011

The Raman effect is typically observed by irradiating a sample with an intense light source and detecting the minute amount of frequency shifted scattered light. We demonstrate that Raman molecular vibrational resonances can be detected directly through an entirely different mechanism—namely, a force measurement. We create a force interaction through optical parametric down conversion between stimulated, Raman excited, molecules on a surface and a cantilevered nanometer scale probe tip brought very close to it. Spectroscopy and microscopy on clusters of molecules have been performed. Single molecules within such clusters are clearly resolved in the Raman micrographs. The technique can be readily extended to perform pump probe experiments for measuring inter- and intramolecular couplings and conformational changes at the single molecule level.
Multiple coherence resonance induced by time-periodic coupling in stochastic Hodgkin–Huxley neuronal networks
Authors: Lin Xiu , Gong Yubing , Wang Li
Published: October 2011

In this paper, we study the effect of time-periodic coupling strength (TPCS) on the spiking coherence of Newman–Watts small-world networks of stochastic Hodgkin–Huxley (HH) neurons and investigate the relations between the coupling strength and channel noise when coherence resonance (CR) occurs. It is found that, when the amplitude of TPCS is varied, the spiking induced by channel noise can exhibit CR and coherence bi-resonance (CBR), and the CR moves to a smaller patch area (bigger channel noise) when the amplitude increases; when the frequency of TPCS is varied, the intrinsic spiking can exhibit CBR and multiple CR, and the CR always occurs when the frequency is equal to or multiple of the spiking period, manifesting as the locking between the frequencies of the intrinsic spiking and the coupling strength. These results show that TPCS can greatly enhance and optimize the intrinsic spiking coherence, and favors the spiking with bigger channel noise to exhibit CR. This implies that, compared to constant coupling strength, TPCS may play a more efficient role for improving the time precision of the information processing in stochastic neuronal networks.
Electrostatic studies of π–π interaction for benzene stacking on a graphene layer
Authors: Hsun Su Yen , Kai Wu Yang , Tu Sheng-Lung , Chang Shoou-Jinn
Published: October 2011

Recently, aromatic molecules have been stacked on graphene for applications in biosensors and chemical sensors, although the interaction between them is not well understood. In this paper, we use electrostatic model, double charge rings, and its image charges model to simulate the π–π interaction between benzene and a graphene layer. Furthermore, the results of our model are confirmed by the numerical results from density functional theory and experimental reviews. This model has potential for use in predicting the interactions between aromatic molecules and graphene.
Sc-phthalocyanine sheet: Promising material for hydrogen storage
Authors: Lü Kun , Zhou Jian , Zhou Le , Wang Qian , Sun Qiang , Jena Puru
Published: October 2011

It has been a long-standing dream to have high surface area materials with isolated and exposed transition-metal ions for hydrogen storage. The flexible synthesis procedure proposed recently by M. Abel, et al. [J. Am. Chem. Soc. 133, 1203 (2011)] and A. Sperl et al. [J. Am. Chem. Soc. 133, 11007 (2011)] provides a different pathway to achieve this goal. Using first-principles theory and grand canonical Monte Carlo simulation, we carry out a systematic study of 3d transition metals (Sc to Zn)-phthalocyanine porous sheets and find that Sc-phthalocyanine can store 4.6 wt. % hydrogen at 298 K and 100 bar.
Communication: A packing of truncated tetrahedra that nearly fills all of space and its melting properties
Authors: Jiao Yang , Torquato Salvatore
Published: October 2011

Dense polyhedron packings are useful models of a variety of condensed matter and biological systems and have intrigued scientists and mathematicians for centuries. Here, we analytically construct the densest known packing of truncated tetrahedra with a remarkably high packing fraction ϕ = 207/208 = 0.995192…, which is amazingly close to unity and strongly implies its optimality. This construction is based on a generalized organizing principle for polyhedra lacking central symmetry that we introduce here. The “holes” in the putative optimal packing are perfect tetrahedra, which leads to a new tessellation of space by truncated tetrahedra and tetrahedra. Its packing characteristics and equilibrium melting properties as the system undergoes decompression are discussed.
Communication: Quasiclassical trajectory calculations of correlated product-state distributions for the dissociation of (H2O)2 and (D2O)2
Authors: Czakó Gábor , Wang Yimin , Bowman Joel M.
Published: October 2011

Stimulated by recent experiments [B. E. Rocher-Casterline, L. C. Ch'ng, A. K. Mollner, and H. Reisler, J. Chem. Phys. 134, 211101 (2011)], we report quasiclassical trajectory calculations of the dissociation dynamics of the water dimer, (H2O)2 (and also (D2O)2) using a full-dimensional ab initio potential energy surface. The dissociation is initiated by exciting the H-bonded OH(OD)-stretch, as done experimentally for (H2O)2. Normal mode analysis of the fragment pairs is done and the correlated vibrational populations are obtained by (a) standard histogram binning (HB), (b) harmonic normal-mode energy-based Gaussian binning (GB), and (c) a modified version of (b) using accurate vibrational energies obtained in the Cartesian space. We show that HB allows opening quantum mechanically closed states, whereas GB, especially via (c), gives physically correct results. Dissociation of both (H2O)2 and (D2O)2 mainly produces either fragment in the bending excited (010) state. The H2O(J) and D2O(J) rotational distributions are similar, peaking at J = 3–5. The computations do not show significant difference between the ro-vibrational distributions of the donor and acceptor fragments. Diffusion Monte Carlo computations are performed for (D2O)2 providing an accurate zero-point energy of 7247 cm−1, and thus, a benchmark D0 of 1244 ± 5 cm−1.
Mechanisms of suppressing secondary nucleation for low-power and low-temperature microwave plasma self-bias-enhanced growth of diamond films in argon diluted methane
Authors: Jiang Ji-heng , Tzeng Yonhua
Published: October 2011

We report on mechanisms for suppressing diamond secondary nucleation in microwave plasma self-bias-enhanced growth (SBEG) of diamond films in methane diluted by argon. High-density plasma at a small distance from the substrate induces a floating potential which promotes high-flux, low-energy ion bombardment on diamond growing surfaces along with an equal flux of electrons. Increased atomic hydrogen generated by electron impact dissociation of methane and low-energy ion bombardment help remove hydrocarbon coatings on diamond grains in favor of continuous grain growth and, therefore, the suppression of secondary diamond nucleation. Energetic meta-stable excited argon, abundant C2 dimers, and enhanced effective surface temperature due to low-energy ion bombardment further promote the diamond grain growth resulting in the deposition of a diamond film with columnar diamond grains of much larger grain sizes and a much lower density of grain boundaries than ultrananocrystalline diamond (UNCD) films grown under similar conditions without optimized plasma-substrate interactions. SEM, XRD, PL, and Raman scattering help confirm the deposition of diamond films with columnar grains.