bluuebunny/crossref_metadata_2025 huggingface dataset:
Clinical and immunological correlates of chest X‐ray abnormalities in HIV‐infected South African children with limited access to anti‐retroviral therapy
Authors: Pitcher Richard D. , Lombard Carl , Cotton Mark F. , Beningfield Stephen J. , Zar Heather J.
Published: August 2013

Background

The chest X‐ray (CXR) abnormalities of human immunodeficiency virus (HIV)‐infected children in low/middle income countries (LMIC's) have not been well studied.

Objective

To describe the CXR abnormalities and associated clinical/immunological features in HIV‐infected South African children.

Materials and Methods

A prospective study of HIV‐infected children who underwent baseline chest radiography and clinical and immunological HIV‐staging. CXR abnormalities were stratified as grade 1 (mild) or grade 2 (moderate/severe). Univariate and multiple logistic regression analyses assessed associations between radiological severity and clinical/immunological parameters.

Results

Three hundred thirty children (53% male), median age 23.8 months, were included; 303 (92%) had moderate/severe clinical disease and 225 (68%) moderate/severe immune suppression; 52 (16%) had a normal CXR; 169 (51%) had grade 2 CXR abnormalities, manifesting as: confluent opacification (n = 91, 28%), nodules (n = 37, 11%), or nodules with opacification (n = 41, 12%) Grade 2 abnormality was associated with more advanced clinical HIV disease (OR: 6.9; 95% CI: 1.9–25.6), CD4+ less than 20% (OR: 1.8; 95% CI: 1.0–3.0) and age over 24 months (OR: 4.1; 95% CI: 2.1–8.0).

Conclusion

CXR abnormalities are common in HIV‐infected children in LMIC's. The extent of radiological abnormality correlates with age and clinical and immunological severity of HIV‐disease. Pediatr Pulmonol. 2014; 49:581–588. © 2013 Wiley Periodicals, Inc.
How to select the most relevant 3D roughness parameters of a surface
Authors: Deltombe R. , Kubiak K. J. , Bigerelle M.
Published: August 2013

In order to conduct a comprehensive roughness analysis, around sixty 3D roughness parameters are created to describe most of the surface morphology with regard to specific functions, properties or applications. In this paper, a multiscale surface topography decomposition method is proposed with application to stainless steel (AISI 304), which is processed by rolling at different fabrication stages and by electrical discharge tool machining. Fifty‐six 3D‐roughness parameters defined in ISO, EUR, and ASME standards are calculated for the measured surfaces. Then, expert software “MesRug” is employed to perform statistical analysis on acquired data in order to find the most relevant parameters characterizing the effect of both processes (rolling and machining), and to determine the most appropriate scale of analysis. For the rolling process: The parameter Vmc (the Core Material Volume—defined as volume of material comprising the texture between heights corresponding to the material ratio values of p = 10% and q = 80%) computed at the scale of 3 µm is the most relevant parameter to characterize the cold rolling process. For the EDM Process, the best roughness parameter is SPD that represents the number of peaks per unit area after segmentation of a surface into motifs computed at the scale of 8 µm. SCANNING 36:150–160, 2014. © 2013 Wiley Periodicals, Inc.
Monitoring auroral electrojets with satellite data
Authors: Vennerstrom S. , Moretto T.
Published: August 2013

The strong horizontal ionospheric currents in the auroral oval constitute an important space weather parameter. Here we present a method to estimate the latitude location and intensity of these currents from measurements of variations in the magnetic field magnitude made by low Earth polar orbiting satellites. The method is simple enough to be implemented for real‐time monitoring, especially since it does not require the full vector field measurement. We demonstrate the method on 5 years of Challenging Minisatellite Payload (CHAMP) data and show how the monitoring depends on the local time of the satellite orbit and how it varies with local time and season in both hemispheres. Statistically, the strongest currents are observed in the predawn and predusk local time quadrants at latitudes that depend on the general magnetic activity level. We also show how the satellite‐derived parameters relate to and complement existing ground‐based indices. The CHAMP magnetometer in 350–450km altitude easily measures an electrojet which on the ground would produce an Auroral Electrojet (AE)‐type signal as small as 20 nT. Thus, while the signal decreases roughly proportionally to the square of the distance to the current, this does not significantly affect the utility of the method for space weather applications even for satellites at substantially higher altitudes. The results for several individual magnetic storm periods demonstrate that large variability can exist in both the latitude and intensity of the currents during the progression of a storm. In the storms analyzed, the latitude of the strongest observed currents are seen to vary between 52° and 84° magnetic latitude.
Symmetry‐adapted perturbation theory based on density functional theory for noncovalent interactions
Authors: Jansen Georg
Published: August 2013

The combination of symmetry‐adapted perturbation theory (SAPT) of intermolecular interactions with a density functional theory (DFT) description of the underlying molecular properties, known as DFT‐SAPT or SAPT(DFT), is reviewed, with a focus on methodology. A theoretical formalism avoiding an overlap expansion and the single‐exchange approximation for the second‐order exchange contributions is presented, and ways to include higher order contributions are discussed. The influence of the exchange‐correlation potential and kernel underlying any DFT‐SAPT calculation will be explicated. Enhancements of the computational efficiency through density fitting are described and comparisons to coupled cluster theory and experiment benchmark the performance of the method.

This article is categorized under:

Structure and Mechanism > Molecular Structures

Electronic Structure Theory > Density Functional Theory

Molecular and Statistical Mechanics > Molecular Interactions
Angehörige in End-of-Life Care – die Vielfalt ihrer Rollen und Herausforderungen
Authors: Pleschberger Sabine
Published: August 2013

Einleitung

Seit mehr als zehn Jahren kann ein wachsendes gesundheitspolitisches und wissenschaftliches Interesse an (pflegenden) Angehörigen verzeichnet werden. Der Forschungsstand hierzu ist im deutschsprachigen Raum allerdings noch immer dürftig, insbesondere im Kontext von End-of-life Care. Das überrascht angesichts des intensiven Diskurses um Hospizarbeit und Palliative Care und der großen Bedeutung, die Angehörige in der Versorgung am Lebensende haben. Über sie wird zumeist die Basisversorgung und Pflege sichergestellt. Angehörige leisten Begleitung, psychische sowie seelische Unterstützung in der letzten Lebensphase, und sie leisten auch einen Beitrag zur sozialen Integration sterbender Menschen. Im Kontext von Gesundheitsförderung sind daher auch die spezifischen Bedürfnisse der Angehörigen in der Bewältigung von Sterben, Tod und Trauer dringend aufzunehmen.
The role of psychological factors in bipolar disorder: prospective relationships between cognitive style, coping style and symptom expression
Authors: Fletcher Kathryn , Parker Gordon , Manicavasagar Vijaya
Published: August 2013

Objective

Psychological factors contribute to bipolar disorder illness course, representing targets for psychological intervention. Research to date has focused on bipolar I disorder, extrapolating results to bipolar II disorder. The current study addresses this discrepancy by exploring cognitive and coping styles in patients diagnosed with bipolar I or II disorder.

Methods

Participants were recruited from the Sydney-based Black Dog Institute. Diagnoses were derived via the MINI International Neuropsychiatric Interview. Baseline cognitive and coping style measures were completed, and mood symptoms assessed over a 6-month period. Clinician-rated mood status was assessed at follow-up to determine the predictive utility of cognitive and coping styles.

Results

The follow-up sample comprised 151 participants. Differential relationships between cognitive style, coping styles and mood symptoms emerged across the bipolar sub-types. Some key differences were that a broader set of negative cognitive styles were associated with bipolar II depression symptoms; while few relationships were observed between coping styles and bipolar II symptoms.

Conclusion

Differences in cognitive and coping style relationships with symptom expression across bipolar I and II disorder may provide clinicians with fruitful guides for directing treatment interventions when relevant maladaptive styles are observed. Further exploration of differences in cognitive and coping styles in bipolar I and II disorder is warranted.
COMPARISON OF MEASURES OF TOTALLY POSITIVE POLYNOMIALS
Authors: FLAMMANG V.
Published: August 2013

In this paper, explicit auxiliary functions are used to get upper and lower bounds for the Mahler measure of monic irreducible totally positive polynomials with integer coefficients. These bounds involve the length and the trace of the polynomial.
COUNTING SYMMETRIC BRACELETS
Authors: ZELENYUK YEVHEN , ZELENYUK YULIYA
Published: August 2013

An $r$-ary necklace (bracelet) of length $n$ is an equivalence class of $r$-colourings of vertices of a regular $n$-gon, taking all rotations (rotations and reflections) as equivalent. A necklace (bracelet) is symmetric if a corresponding colouring is invariant under some reflection. We show that the number of symmetric $r$-ary necklaces (bracelets) of length $n$ is $\frac{1}{2} (r+ 1){r}^{n/ 2} $ if $n$ is even, and ${r}^{(n+ 1)/ 2} $ if $n$ is odd.
Effects of pea (Pisum sativum L.) cultivars on Thrips tabaci Lindeman preference and performance
Authors: POBOŻNIAK M. , KOSCHIER E. H.
Published: August 2013

The polyphagous onion thrips Thrips tabaci Lindeman (Thysanoptera: Thripidae) is a serious pest in many protected and field crops and has recently been found to occur in high numbers in Pisum sativum L. crops. In the present study, the abundance of T. tabaci was compared on two pea cultivars in the field. Data on sweep net catches at different sampling times during the day suggest that peak activity of the thrips is at noon. Significantly more thrips larvae and adults were caught on the early pea cultivar Cud Kelwedonu compared with the very early cultivar Pionier, particularly during and after flowering of the peas. Analysis of primary plant compounds indicated that the higher leaf nitrogen and sucrose contents in the leaves of cvar Cud Kelwedonu promote thrips population growth in pea. The preference of T. tabaci for leaves of cvar Cud Kelwedonu was confirmed in experiments in the laboratory. Thrips tended to settle, caused significantly more feeding damage and laid significantly more eggs on the leaves of Cud Kelwedonu. Knowledge on abundance, activity patterns and host use of T. tabaci in pea may contribute to optimizing cultivar selection, monitoring and timing of possible control measures in the future.
Twin Imperial Disasters. The invasions of Khiva and Afghanistan in the Russian and British official mind, 1839–1842
Authors: MORRISON ALEXANDER
Published: August 2013

This paper examines two linked cases of abortive Imperial expansion. The British invasion of Afghanistan and the Russian winter expedition to Khiva both took place in 1839, and both ended in disaster. These events were linked, not merely by coincidence, but by mutual reactions to intelligence received in Orenburg, St Petersburg, Calcutta, London, and Tehran. British and Russian officials shared similar fears about each other's ambitions in Central Asia, similar patterns of prejudice, arrogance and ignorance, and a similar sense of entitlement as the self-conscious agents of two ‘Great Powers’. By examining the decision-making process which preceded these twin cases of expansion, and the British and Russian attitudes to Central Asian rulers and informants, the paper provides not only a deeper understanding of what provoked these particular disasters, but also of the wider process of European imperial expansion in the early nineteenth century.
Life-long singlehood: intersections of the past and the present
Authors: TIMONEN VIRPI , DOYLE MARTHA
Published: August 2013

This paper examines life-long singlehood and its ramifications in old age among women and men in Ireland. During the life-time of the 26 research participants, Ireland shifted from the Western European marriage pattern, characterised by high rates of singlehood, late marriage and high fertility, to declining prevalence of singlehood, higher marriage rates and lower fertility. In-depth interviews were analysed with the help of narrative analysis and grounded theory methods. We identified two main pathways into singlehood that had a long-term impact on the participants' lives. The women and men who hadchosensinglehood associated this status with independence, self-fulfilment and autonomy throughout their lifecourse, including in old age. In contrast, older adults who had beenconstrainedin their choice of marital status due to poverty, care work, family roles and cultural norms, expressed regret and dissatisfaction with their single status. In the latter group, the ramifications of the inability to actualise the roles of a spouse, parent and grandparent were particularly apposite in later life when many felt the absence of close ties and expressed loneliness. For some of the older adults who had been constrained in their choice of marital status in earlier life, the possibility of entering into a romantic relationship seemed more feasible in later life. How older adults interpret their pathway into the single status in earlier life impacts on relationship formation and life satisfaction in older age.
Trapping of electromagnetic radiation in self-generated and preformed cavities
Authors: Luan Shixia , Yu Wei , Wang Jingwei , Yu Mingyang , Weng Suming , Murakami Masakatsu , Wang Jingwei , Xu Han , Zhuo Hongbin
Published: August 2013

Laser light trapping in cavities in near-critical density plasmas is studied by two-dimensional particle-in-cell simulation. The laser ponderomotive force can create in the plasma a vacuum cavity bounded by a thin overcritical-density wall. The laser light is self-consistently trapped as a half-cycle electromagnetic wave in the form of an oscillon-caviton structure until it is slowly depleted through interaction with the cavity wall. When the near-critical density plasma contains a preformed cavity, laser light can become a standing wave in the latter. The trapped light is characterized as multi-peak structure. The overdense plasma wall around the self-generated and preformed cavities induced by the laser ponderomotive force is found to be crucial for pulse trapping. Once this wall forms, the trapped pulse can hardly penetrate.
Effects of substituting anthropometric joints with revolute joints in humanoid robots and robotic hands: a case study
Authors: Mousavi Mehdi , Somà Aurelio , Pescarmona Francesco
Published: August 2013

In the human body there are many joints whose functions are very similar to revolute joints. To avoid the complexity of these joints, they are usually substituted by revolute joints in many humanoid robots. Revolute joints have purely rotational motion along their fixed axis, while real joints in the human body have Instantaneous Rotational Axis (IRA) due to their configuration. Substitution of this kind of human joints with revolute (hinge) joints in robots changes the kinematics of joints. Knowing the exact characteristics of the moving axis of rotation in human joints is a prerequisite for the kinematic study of a joint. Here the main geometrical difference between these kinds of joints in humans and their simplified (hinge-like) models in robots is described. Then, as a case study, the mechanism of the three joints of the index finger are compared with their hinge-like model using a multi-body code to understand when revolute joints can be substituted for anthropometric joints in hand exoskeletons and robotic hands. Furthermore, the position of IRA and its distance from the center of the condyle of the joint are presented. The concept and the results can be extended for other fingers and all similar joints, and can be used in humanoid robots, hand exoskeletons and robotic hands.
Radiotherapy scheduling using prime numbers
Authors: McLaughlin J. , Marignol L.
Published: August 2013

Background

The optimal delivery of radiation therapy to achieve maximum tumour cell kill while limiting damage to normal tissues underlies any radiation therapy treatment protocol. The biological effectiveness of radiation therapy is closely related to cellular reproductive activity. The scheduling of dose fraction to a time where actively dividing cells are at their most radiosensitive stage (RS) has potential to enhance therapeutic efficacy.

Materials and methods

A prime number is a natural number >1 whose only divisors are 1 and the number itself.

Purpose

We propose that the use of prime numbers in the scheduling of radiotherapy treatments could maximise biological effectiveness by facilitating the irradiation of the greatest number of cells at their most RS stage, and ultimately improve the therapeutic ratio of radiation therapy.

Conclusions

The theoretical clinical implementation of this concept into the scheduling of radiation therapy is discussed.
A preliminary investigation of cultivated and wild species ofLuffafor oil and protein contents
Authors: Prakash Krishna , Radhamani Jalli , Pandey Anjula , Yadav Sangita
Published: August 2013

Seeds of wild and cultivated species ofLuffawere studied to determine the variability in morphological (seed size, colour, seed-coat surface and 100-seed weight) and biochemical (oil and protein) characteristics. A total of 80 accessions of three cultivated species (71 accessions) and three wild species (9 accessions) ofLuffaunder the present investigation from diverse regions (12 states of five regions) of India showed variations in seed size, colour, seed-coat surface, 100-seed weight, and seed protein and oil contents both within the accessions of the same species and between different species. Significant variability in seed morphological traits was observed. Both seed oil and soluble seed protein contents were highest in some accessions of the cultivated species (25–27% oil and 8–10% protein, respectively, on a fresh seed weight basis). Using the 2D scatter plot diagram derived from the principal components analysis, the morphological and biochemical traits of the 80Luffaaccessions classified the wild species into one cluster (cluster I) and the cultivated species into a second major cluster (cluster II). The present investigation on the correlation between seed morphology and biochemical traits in the cultivated and wild species ofLuffacan help in identifying the genotypes ofLuffaspecies with valuable traits for further exploring the potential of this valuable crop as a source of edible oil, food and fodder in edible seed types or as a source of industrial oil/biodiesel in non-edible seed types. The protein-rich seed could be further explored to be utilized in the fortification of food products for value addition.
Herzinsuffizienz-Up to Date
Authors: Müller-Edenborn Björn , Eriksson Urs
Published: August 2013

Die Herzinsuffizienz ist häufig und verursacht hohe sozial-ökonomische Kosten. Der Hausarzt ist der erste Ansprechpartner für die meisten Patienten. Um effizient abzuklären und sinnvolle Therapieentscheidungen zu treffen, ist die Kenntnis der zugrundeliegenden Ursachen und der medikamentösen wie nicht-medikamentösen Behandlungsoptionen zentral. Ziele sind längeres Überleben und bessere Lebensqualität. Entscheidend ist einerseits die Vermeidung unnötiger Hospitalisationen, andererseits gilt es zum richtigen Zeitpunkt die notwendigen Spezialisten zu involvieren.
Therapien der Multiplen Sklerose
Authors: Kesselring Jürg
Published: August 2013

Auch wenn es noch keine Heilungsmöglichkeit für die Multiple Sklerose (MS) gibt, so stehen doch wirksame Strategien zur Verfügung, um den Krankheitsverlauf zu modifizieren, die Schübe und Symptome zu behandeln, Funktionen zu verbessern und Unterstützung im emotionalen und sozialen Bereich zu gewährleisten. In Kombination können solche Behandlungen die Lebensqualität der MS-Betroffenen verbessern.
Alteplase Treatment does not Increase Brain Injury After Mechanical Middle Cerebral Artery Occlusion in the Rat
Authors: Sutherland Brad A , Buchan Alastair M
Published: August 2013

Recanalization of an occluded vessel with recombinant tissue plasminogen activator is an effective strategy for treating acute ischemic stroke. Recombinant tissue plasminogen activator is administered as alteplase, a formulation containing many excipients including L-arginine, the substrate for nitric oxide production. Most studies fail to compare the effects of alteplase on brain injury to its L-arginine carrier solution. This study aimed to verify the previously reported detrimental effects of alteplase after cerebral ischemia and delineate the contribution of L-arginine. Male Wistar rats, subjected to 90 minutes of intraluminal middle cerebral artery occlusion (MCAO), were administered alteplase, the carrier solution or saline upon reperfusion. Neither alteplase nor the carrier affected cerebral blood flow (CBF) restoration throughout the first 60 minutes of reperfusion. Alteplase treatment was associated with increased mortality after MCAO. Twenty-four hours after MCAO, neurologic function and infarct volume did not differ between rats treated with alteplase, the carrier solution, or saline. Irrespective of treatment group, infarct volume was correlated with CBF during reperfusion, neuroscore, and peri-infarct depolarizations. These results suggest that alteplase treatment, independent of thrombolysis, does not cause increased ischemic injury compared with its appropriate carrier solution, supporting the continued use of alteplase in eligible ischemic stroke patients.
Netrin-1 Overexpression Promotes White Matter Repairing and Remodeling after Focal Cerebral Ischemia in Mice
Authors: He Xiaosong , Li Yaning , Lu Haiyan , Zhang Zhijun , Wang Yongting , Yang Guo-Yuan
Published: August 2013

Damage of oligodendrocytes after ischemia has negative impact on white matter integrity and neuronal function. In this work, we explore whether Netrin-1 (NT-1) overexpression facilitates white matter repairing and remodeling. Adult CD-1 mice received stereotactic injection of adeno-associated virus carrying NT-1 gene ( AAV-NT-1). One week after gene transfer, mice underwent 60 minutes of middle cerebral artery occlusion. The effect of NT-1 on neural function was evaluated by neurobehavioral tests. Proliferated oligodendrocyte progenitor cells (OPCs), newly matured oligodendrocytes, and remyelination were semi-quantified by immunohistochemistry. The role of NT-1 in oligodendrogenesis was further explored by examining specific NT-1 receptors and their function. Netrin-1 overexpression was detected in neurons and astrocytes 2 weeks after AAV-NT-1 gene transfer and significantly improved the neurobehavioral outcomes compared with the control ( P<0.05). In comparison with the control, proliferated OPCs, newly matured oligodendrocytes, and remyelination were greatly increased in the ipsilateral hemisphere of AAV-NT-1-transduced mice. Furthermore, both NT-1 receptors deleted in colorectal carcinoma and UNC5H2 were expressed on OPCs whereas only UNC5H2 was expressed in myelinated axons. Our study indicated that NT-1 promoted OPC proliferation, differentiation, and increased remyelination, suggesting that NT-1 is a promising factor for white matter repairing and remodeling after ischemia.
Joint detection/decoding algorithms for non‐binary low‐density parity‐check codes over inter‐symbol interference channels
Authors: Zhao Shancheng , Lu Zhifei , Ma Xiao , Bai Baoming
Published: August 2013

This study is concerned with the application of non‐binary low‐density parity‐check (NB‐LDPC) codes to binary input inter‐symbol interference channels. Two low‐complexity joint detection/decoding algorithms are proposed. One is referred to as max‐log‐MAP/X‐EMS algorithm, which is implemented by exchanging soft messages between the max‐log‐MAP detector and the extended min‐sum (EMS) decoder. The max‐log‐MAP/X‐EMS algorithm is applicable to general NB‐LDPC codes. The other one, referred to as Viterbi/GMLGD algorithm, is designed in particular for majority‐logic decodable NB‐LDPC codes. The Viterbi/GMLGD algorithm works in an iterative manner by exchanging hard‐decisions between the Viterbi detector and the generalised majority‐logic decoder (GMLGD). As a by‐product, a variant of the original EMS algorithm is proposed, which is referred to as µ‐EMS algorithm. In the µ‐EMS algorithm, the messages are truncated according to an adaptive threshold, resulting in a more efficient algorithm. Simulations results show that the max‐log‐MAP/X‐EMS algorithm performs as well as the traditional iterative detection/decoding algorithm based on the BCJR algorithm and theQ‐ary sum–product algorithm, but with lower complexity. The complexity can be further reduced for majority‐logic decodable NB‐LDPC codes by executing the Viterbi/GMLGD algorithm with a performance degradation within one dB. These algorithms provide good candidates for trade‐offs between performance and complexity.
Cooperative spectrum sensing using opportunistic amplify‐and‐forward relaying over Nakagami‐m fading channels
Authors: Ren Defeng , Ge Jianhua , Li Jing , Ji Yancheng
Published: August 2013

In this study, the authors present a cooperative spectrum sensing scheme based on opportunistic amplify‐and‐forward relaying (denoted by CSS‐OAFR), which provides higher detection performance by selecting the best cognitive relay and is interesting in distributed cognitive radio networks. Moreover, the authors focus on the detection performance using the energy detector over independent and non‐identically distributed Nakagami‐m fading channels. In particular, a tight closed‐form lower bound of the average missed‐detection probability is derived for the convenience of performance evaluation in practice. Finally, simulations are provided to validate the CSS‐OAFR scheme and the derived closed‐form lower bound.
Low complexity scheme for carrier frequency offset estimation in orthogonal frequency division multiple access uplink
Authors: Shah Hardip K. , Dasgupta Kankar S. , Soni Himanshu
Published: August 2013

Maximum likelihood (ML) carrier‐frequency offset estimation for orthogonal frequency‐division multiple access uplink is a complex multi‐parameter estimation problem. The ML approach is a global optima search problem, which is prohibitive for practical applications because of the requirement of multidimensional exhaustive search for a large number of users. There are a few attempts to reduce the complexity of ML search by applying evolutionary optimisation algorithms. In this study, the authors propose a novel canonical particle swarm optimisation (CPSO)‐based scheme, to reduce the computational complexity without compromising the performance and premature convergence. The proposed technique is a two‐step process, where, in the first step, low resolution alternating projection frequency estimation (APFE) is used to generate a single better positioned particle for CPSO, followed by an actual CPSO procedure in second step. The mean square error performance of the proposed scheme is compared with existing low complexity algorithms namely APFE and linear particle swarm optimisation with mutation. Simulation results presented in this study show that the new scheme completely avoids premature convergence for a large number of users as high as 32.
Analytical power allocation for a full‐duplex decode‐and‐forward relay channel
Authors: Emadi Mohammad Javad , Gholami Davoodi Arash , Aref Mohammad Reza
Published: August 2013

For a fading full‐duplex decode‐and‐forward relay channel, the authors analytically derive optimum power allocation schemes subject to individual power constraints at the source and the relay. The authors prove that the problem is a convex optimisation problem over the feasible power set, and by proposing a systematic technique to solve min–max problems, optimum power allocations are derived in closed‐forms. Finally, for a Rayleigh‐fading channel model, optimum power allocations are derived and the respective achievable rate and an upper bound are evaluated. The implications of the derived theoretical results are discussed through some graphs.
X‐parameter‐based modelling of polar modulated power amplifiers
Authors: Wang Yelin , Nielsen Troels Studsgaard , Sira Daniel , Jensen Ole Kiel , Larsen Torben
Published: August 2013

X‐parameters are developed as an extension of S‐parameters capable of modelling non‐linear devices driven by large signals. They are suitable for devices having only radio frequency (RF) and DC ports. In a polar power amplifier (PA), phase and envelope of the input modulated signal are applied at separate ports and the envelope port is neither an RF nor a DC port. As a result, X‐parameters may fail to characterise the effect of the envelope port excitation and consequently the polar PA. This study introduces a solution to the problem for a commercial polar PA. In this solution, the RF‐phase path is modelled by X‐parameters and the envelope path of the polar PA is simulated by a low‐pass filter. The solution can be applied to a group of polar PAs who have the similar topology and design as the one in this work. Modulated signals with different channel bandwidths were applied to the model of the polar PA for simulations. The simulated error vector magnitude (EVM) and adjacent channel power ratio (ACPR) were compared with the measured data to validate the model. The maximum differences between the simulated and measured EVM and ACPR are less than 2% point and 3 dB, respectively.
Compact ultra‐wideband bandpass filters with narrow notched bands based on a ring resonator
Authors: Feng Wenjie , Che Wenquan , Xue Quan
Published: August 2013

In this study, compact ultra‐wideband (UWB) bandpass filters with single/dual‐notched bands are proposed based on a ring resonator and transversal signal‐interference concept. Broad passband and narrow notched bands with controlled even/odd‐mode resonator frequencies can be adjusted conveniently by changing the characteristic impedance of the ring resonator. Transmission zeros are introduced to improve selectivity and harmonic suppression of the proposed UWB bandpass filters with notched bands. To verify the presented strategies, three prototypes (εr = 2.65, h = 0.5 mm) with 3 dB fractional bandwidth >120% are designed and fabricated. Simple structure and good in/out‐of‐band performances can be achieved in the proposed UWB bandpass filters.
Independently switchable quad‐band bandpass filter
Authors: Weng Sz‐Chi , Hsu Ko‐Wen , Tu Wen‐Hua
Published: August 2013

A switchable microstrip quad‐band bandpass filter (BPS) is investigated in this study. Owing to the low loading effect from distributed coupling technique, many channels can be obtained without the requiring of complicated matching network. Each passband can be turned on and off independently. The switchable quad‐band BPS consisting of half‐wavelength/quarter‐wavelength resonators, loaded open stubs and p–i–n diodes features compactness and good selectivity. To validate this design concept, theory as well as experiment is presented and compared in this study.
Overview of wireless power transfer technologies for electric vehicle battery charging
Authors: Musavi Fariborz , Eberle Wilson
Published: August 2013

In this study, a comprehensive review of existing technological solutions for wireless power transfer used in electric vehicle battery chargers is given. The concept of each solution is thoroughly reviewed and the feasibility is evaluated considering the present limitations in power electronics technology, cost and consumer acceptance. In addition, the challenges and advantages of each technology are discussed. Finally, a thorough comparison is made and a proposed mixed conductive/wireless charging system solution is suggested to solve the inherent existing problems.
Light‐emitting diode driver with low‐frequency ripple suppressed and dimming efficiency improved
Authors: Hwu Kuo‐Ing , Tu Wei‐Cheng , Lai Chung‐Yu
Published: August 2013

In this study, a single‐stage power‐factor‐corrected flyback converter is used as the main power stage, which is controlled by a critical mode control integrated circuit and is used to drive light‐emitting diode (LED) strings. Since the output voltage of this converter possesses a double line frequency ripple, one energy‐recycling circuit without any control is added to render the instantaneous output power close to the instantaneous input power, so as to reduce the energy stored/released in the output capacitor and hence to reduce the output voltage ripple of the double line frequency. Accordingly, the effect of the low‐frequency voltage ripple on the colour, luminance, life and stability of the LED can be reduced. For the dimming circuit to be considered, the gate voltage detecting circuit is employed herein so as to achieve efficiency improvement in LED dimming. Based on the dimming command and the variation in gate voltage, the voltage reference command for the flyback converter is dynamically adjusted so as to make the voltage across the metal oxide semiconductor field effect transistor reduced as the LED string is dimmed up/down and hence to increase the efficiency of the overall system.
Effects of dust size distribution on dust negative ion acoustic solitary waves in a magnetized dusty plasma
Authors: Ma Yi-Rong , Qi Xin , Sun Jian-An , Duan Wen-Shan , Yang Lei
Published: August 2013

Dust negative ion acoustic solitary waves in a magnetized multi-ion dusty plasma containing hot isothermal electron, ions (light positive ions and heavy negative ions) and extremely massive charge fluctuating dust grains are investigated by employing the reductive perturbation method. How the dust size distribution affect the height and the thickness of the nonlinear solitary wave are given. It is noted that the characteristic of the solitary waves are different with the different dust size distribution. The magnitude of the external magnetic field also affects the solitary wave form.
Physics of rheologically enhanced propulsion: Different strokes in generalized Stokes
Authors: Montenegro-Johnson Thomas D. , Smith David J. , Loghin Daniel
Published: August 2013

Shear-thinning is an important rheological property of many biological fluids, such as mucus, whereby the apparent viscosity of the fluid decreases with shear. Certain microscopic swimmers have been shown to progress more rapidly through shear-thinning fluids, but is this behavior generic to all microscopic swimmers, and what are the physics through which shear-thinning rheology affects a swimmer's propulsion? We examine swimmers employing prescribed stroke kinematics in two-dimensional, inertialess Carreau fluid: shear-thinning “generalized Stokes” flow. Swimmers are modeled, using the method of femlets, by a set of immersed, regularized forces. The equations governing the fluid dynamics are then discretized over a body-fitted mesh and solved with the finite element method. We analyze the locomotion of three distinct classes of microswimmer: (1) conceptual swimmers comprising sliding spheres employing both one- and two-dimensional strokes, (2) slip-velocity envelope models of ciliates commonly referred to as “squirmers,” and (3) monoflagellate pushers, such as sperm. We find that morphologically identical swimmers with different strokes may swim either faster or slower in shear-thinning fluids than in Newtonian fluids. We explain this kinematic sensitivity by considering differences in the viscosity of the fluid surrounding propulsive and payload elements of the swimmer, and using this insight suggest two reciprocal sliding sphere swimmers which violate Purcell's Scallop theorem in shear-thinning fluids. We also show that an increased flow decay rate arising from shear-thinning rheology is associated with a reduction in the swimming speed of slip-velocity squirmers. For sperm-like swimmers, a gradient of thick to thin fluid along the flagellum alters the force it exerts upon the fluid, flattening trajectories and increasing instantaneous swimming speed.
On the notch sensitivity of CuZr metallic glasses
Authors: Sha Zhen-Dong , Pei Qing-Xiang , Sorkin Viacheslav , Branicio Paulo S. , Zhang Yong-Wei , Gao Huajian
Published: August 2013

Atomistic simulations are performed to study the effects of size and shape of a superficial or internal notch on the strength and failure mechanism of CuZr metallic glass (MG) under tensile loading. Our results show that plastic deformation originating at the notch root reduces the stress concentration there and leads to a notch-insensitive normalized tensile strength. The notch, however, dictates the failure location as the plastic zone at the notch root serves as a nucleation site for shear band (SB) formation. It is shown that when the plastic zone size reaches a critical value, a SB starts to propagate from the notch root across the entire sample, causing the material failure. These results provide useful guidelines for the design, testing, and engineering of MG for structural applications.
Phosphorus starvation boosts carboxylate secretion in P-deficient genotypes of Lupinus angustifolius with contrasting root structure
Authors: Chen Ying L. , Dunbabin Vanessa M. , Diggle Art J. , Siddique Kadambot H. M. , Rengel Zed
Published: August 2013

Lupinus angustifolius L. (narrow-leafed lupin) is an important grain legume crop for the stockfeed industry in Australia. This species does not form cluster roots regardless of phosphorus (P) nutrition. We hypothesise that this species may have adaptive strategies for achieving critical P uptake in low-P environments by altering shoot growth and root architecture and secreting carboxylates from roots. Three wild genotypes of L. angustifolius with contrasting root architecture were selected to investigate the influence of P starvation on root growth and rhizosphere carboxylate exudation and their relationship with P acquisition. Plants were grown in sterilised loamy soil supplied with zero, low (50 μm) or optimal (400 μm) P for 6 weeks. All genotypes showed a significant response in shoot and root development to varying P supply. At P deficit (zero and low P), root systems were smaller and had fewer branches than did roots at optimal P. The amount of total carboxylates in the rhizosphere extracts ranged from 3.4 to 17.3 μmol g–1 dry root. The total carboxylates comprised primarily citrate (61–78% in various P treatments), followed by malate and acetate. Genotype #085 (large root system with deep lateral roots) exuded the greatest amount of total carboxylates to the rhizosphere for each P treatment, followed by #016 (medium root system with good branched lateral roots) and #044 (small root system with short and sparse lateral roots). All genotypes in the low-P treatment significantly enhanced exudation of carboxylates, whereas no significant increase in carboxylate exudation was observed in the zero-P treatment. Small-rooted genotypes had higher P concentration than the medium- and large-rooted genotypes, although larger plants accumulated higher total P content. Large-rooted genotypes increased shoot P utilisation efficiency in response to P starvation. This study showed that narrow-leafed lupin genotypes differing in root architecture differed in carboxylate exudation and P uptake. Our finding suggested that for L. angustifolius there is a minimum plant P concentration below which carboxylate exudation is not enhanced despite severe P deficiency. The outcomes of this study enhance our understanding of P acquisition strategies in L. angustifolius genotypes, which can be used for the selection of P-efficient genotypes for cropping systems.
Using phytohaemagglutinin to determine immune responsiveness in saltwater crocodiles (Crocodylus porosus)
Authors: Finger Jr John W. , Adams Amanda L. , Thomson Peter C. , Shilton Cathy M. , Brown Greg P. , Moran Christopher , Miles Lee G. , Glenn Travis C. , Isberg Sally R.
Published: August 2013

Immune responsiveness, the ability of an organism to effectively respond immunologically following antigenic exposure, is an essential component of life history, as organisms require effective immune functionality in order to grow, survive and reproduce. However, immune status is also associated with concomitant trade-offs in these physiological functions. Herein we demonstrate the validation of phytohaemagglutinin (PHA) injection in saltwater crocodiles, Crocodylus porosus, to assess cellular immune responsiveness. Following injection of 2 mg mL–1 PHA into the hind toe webbing, we observed a peak swelling response 12 h after injection, with PHA inducing increased thickness compared with webs injected with phosphate-buffered saline (PBS) (F5,518 = 145.13, P < 0.001). Subsequent injections increased responsiveness relative to the primary injection response (F5,290 = 2.92, P = 0.029), suggesting that PHA exposure induced immunological memory, a tenet of acquired immunity. Histological examination revealed that PHA-injected toe webs displayed increased numbers of leukocytes (granulocytes, macrophages, and lymphocytes) relative to PBS-injected webs, with peak leukocytic infiltrate observed 12 h after injection. We suggest the use of PHA injection in crocodilians as a measure of cellular immune responsiveness in agricultural (production and animal welfare), ecological, and toxicological contexts.
The growth speed of microtubules with XMAP215-coated beads coupled to their ends is increased by tensile force
Authors: Trushko Anastasiya , Schäffer Erik , Howard Jonathon
Published: August 2013

The generation of pulling and pushing forces is one of the important functions of microtubules, which are dynamic and polarized structures. The ends of dynamic microtubules are able to form relatively stable links to cellular structures, so that when a microtubule grows it can exert a pushing force and when it shrinks it can exert a pulling force. Microtubule growth and shrinkage are tightly regulated by microtubule-associated proteins (MAPs) that bind to microtubule ends. Given their localization, MAPs may be exposed to compressive and tensile forces. The effect of such forces on MAP function, however, is poorly understood. Here we show that beads coated with the microtubule polymerizing protein XMAP215, the Xenopus homolog of Dis1 and chTOG, are able to link stably to the plus ends of microtubules, even when the ends are growing or shrinking; at growing ends, the beads increase the polymerization rate. Using optical tweezers, we found that tensile force further increased the microtubule polymerization rate. These results show that physical forces can regulate the activity of MAPs. Furthermore, our results show that XMAP215 can be used as a handle to sense and mechanically manipulate the dynamics of the microtubule tip.
Axial interactions in the mixed-valent Cu
A
active site and role of the axial methionine in electron transfer
Authors: Tsai Ming-Li , Hadt Ryan G. , Marshall Nicholas M. , Wilson Tiffany D. , Lu Yi , Solomon Edward I.
Published: August 2013

Significance

Long-range electron transfer (ET) is vital in energy transduction pathways. Within metalloprotein ET active sites, the role of the axial ligand in the mononuclear, blue copper (BC), also called type 1 Cu, sites is well defined, whereas its role in the binuclear mixed-valent Cu
A
sites is less clear. This study defines the axial interaction in the mixed-valent binuclear Cu
A
active site and its role in ET. The axial S(Met) ligand is essential in tuning down the reduction potential while not increasing the inner-sphere reorganization energy, a similar role to that found for the S(Met) ligand in BC. Furthermore, much like BC, the S(Met) bond in Cu
A
is weak and therefore under entatic control by the surrounding protein matrix.
One-parameter families of circle diffeomorphisms with strictly monotone rotation number
Authors: Parkhe Kiran
Published: August 2013

We show that if

f
:

S
1

×

S
1

→

S
1

×

S
1

f \colon S^1 \times S^1 \to S^1 \times S^1

is

C
2

C^2

, with

f
(
x
,
t
)
=
(

f
t

(
x
)
,
t
)

f(x, t) = (f_t(x), t)

, and the rotation number of

f
t

f_t

is equal to

t
t

for all

t
∈

S
1

t \in S^1

, then

f
f

is topologically conjugate to the linear Dehn twist of the torus

(

1

a
m
p
;
1

0

a
m
p
;
1

)

\left ( \begin {smallmatrix} 1&1\\ 0&1 \end {smallmatrix} \right )

. We prove a differentiability result where the assumption that the rotation number of

f
t

f_t

is

t
t

is weakened to say that the rotation number is strictly monotone in

t
t

.
Results on Witt kernels of quadratic forms for multi-quadratic extensions
Authors: Aravire Roberto , Laghribi Ahmed
Published: August 2013

In this paper we compute the Witt kernel of quadratic forms for the composition of a purely inseparable multi-quadratic extension with a separable quadratic extension. We also include the case of a multi-quadratic purely inseparable extension by completing the proof given before by the second author for such an extension.
Protein kinase C activation decreases peripheral actin network density and increases central nonmuscle myosin II contractility in neuronal growth cones
Authors: Yang Qing , Zhang Xiao-Feng , Van Goor David , Dunn Ashleigh P. , Hyland Callen , Medeiros Nelson , Forscher Paul
Published: August 2013

Protein kinase C (PKC) can dramatically alter cell structure and motility via effects on actin filament networks. In neurons, PKC activation has been implicated in repulsive guidance responses and inhibition of axon regeneration; however, the cytoskeletal mechanisms underlying these effects are not well understood. Here we investigate the acute effects of PKC activation on actin network structure and dynamics in large Aplysia neuronal growth cones. We provide evidence of a novel two-tiered mechanism of PKC action: 1) PKC activity enhances myosin II regulatory light chain phosphorylation and C-kinase–potentiated protein phosphatase inhibitor phosphorylation. These effects are correlated with increased contractility in the central cytoplasmic domain. 2) PKC activation results in significant reduction of P-domain actin network density accompanied by Arp2/3 complex delocalization from the leading edge and increased rates of retrograde actin network flow. Our results show that PKC activation strongly affects both actin polymerization and myosin II contractility. This synergistic mode of action is relevant to understanding the pleiotropic reported effects of PKC on neuronal growth and regeneration.