bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of different treatments of long‐range interactions and sampling conditions in molecular dynamic simulations of rhodopsin embedded in a dipalmitoyl phosphatidylcholine bilayer
Authors: Cordomí Arnau , Edholm Olle , Perez Juan J.
Published: February 2007

The present study analyzes the effect of the simulation conditions on the results of molecular dynamics simulations of G‐protein coupled receptors (GPCRs) performed with an explicit lipid bilayer. Accordingly, the present work reports the analysis of different simulations of bovine rhodopsin embedded in a dipalmitoyl phosphatidylcholine (DPPC) lipid bilayer using two different sampling conditions and two different approaches for the treatment of long‐range electrostatic interactions. Specifically, sampling was carried out either by using the statistical ensembles NVT or NPT (constant number of atoms, a pressure of 1 atm in all directions and fixed temperature), and the electrostatic interactions were treated either by using a twin‐cutoff, or the particle mesh Ewald summation method (PME). The results of the present study suggest that the use of the NPT ensemble in combination with the PME method provide more realistic simulations. The use of NPT during the equilibration avoids the need of an a priori estimation of the box dimensions, giving the correct area per lipid. However, once the system is equilibrated, the simulations are irrespective of the sampling conditions used. The use of an electrostatic cutoff induces artifacts on both lipid thickness and the ion distribution, but has no direct effect on the protein and water molecules. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007
Migration and welfare: a very simple model
Authors: Cellini Roberto
Published: February 2007

The paper presents a very simple model of migration, relying on three widely accepted points: first, labour productivity and wages in a country depend on the present average human capital; second, agents maximise their utility, so that migration decisions depend on the wage gap across economies; third, the larger the personal human capital, the higher the propensity is to migrate (ceteris paribus). The model shows that migration through its external effects always lowers the welfare in the sending country, while the effects on the receiving country can be positive or negative. As a consequence, selfish developed economies could desire a larger migration than the optimal level for a benevolent World Planner. This calls for international coordination concerning the regulation of migration flows. Copyright © 2007 John Wiley & Sons, Ltd.
Defective axonal transport in motor neuron disease
Authors: El‐Kadi Ali Morsi , Soura Violetta , Hafezparast Majid
Published: February 2007

Several recent studies have highlighted the role of axonal transport in the pathogenesis of motor neuron diseases. Mutations in genes that control microtubule regulation and dynamics have been shown to cause motor neuron degeneration in mice and in a form of human motor neuron disease. In addition, mutations in the molecular motors dynein and kinesins and several proteins associated with the membranes of intracellular vesicles that undergo transport cause motor neuron degeneration in humans and mice. Paradoxically, evidence from studies on the legs at odd angles (Loa) mouse and a transgenic mouse model for human motor neuron disease suggest that partial limitation of the function of dynein may in fact lead to improved axonal transport in the transgenic mouse, leading to delayed disease onset and increased life span. © 2007 Wiley‐Liss, Inc.
Flandrian sea‐level changes in the Fenland. I: The geographical setting and evidence of relative sea‐level changes
Authors: Shennan Ian
Published: February 2007

The Flandrian sediments of the Fenland record the infilling of the Wash embayment on the east coast of England, UK. Since at least 6500 BP changes in sea level have been a major control on the rate and pattern of sediment accumulation. New data are presented from the area which together with published information allow the reconstruction of palaeoenvironments from 6500 to 2500 BP. The major environmental changes involved alternations between freshwater fen and intertidal marine sedimentation. Each episode was characterised by transitional changes as vegetation and sediment zones shifted over large areas. Marine/brackish sediments are found up to 45 km inland of the present coast. Radiocarbon dated sea‐level index points, with relevant stratigraphic and micropalaeontological data, ranging from 6415 BP at −8.17m OD to 2595 BP at +1.45m OD, are described.
Studies on the properties of citrate derivatives of cassava (Manihot esculenta Crantz) starch synthesized by microwave technique
Authors: Jyothi Alummoottil N , Moorthy Subramoney N , Sreekumar Janardhanan Nair , Rajasekharan Kallikat N
Published: February 2007

Cassava starch citrates with degree of substitution (DS) ranging from 0.005 to 0.063 were synthesized by the microwave‐assisted reaction of cassava starch with citric acid. A response surface small composite design was used to study the effect of different reaction conditions, viz. time, temperature and reagent concentration. All these variables significantly affected the substitution level in the modified starches. The DS increased with increase in the time of reaction and temperature. However, reagent concentration had a negative effect on the DS. The modified starches showed higher viscosity with lower breakdown, lower setback and higher final viscosities in comparison to native starch. Differential scanning calorimetry showed that the modified starches exhibited a decrease in gelatinization temperatures, To, Tp, Te, in comparison to native starch. However, the heat of gelatinization was not significantly affected. The citrate derivatives exhibited reduced swelling volume and enhanced water binding capacities. They were found to be less susceptible to enzyme hydrolysis than native starch. Copyright © 2007 Society of Chemical Industry
Controlling the surface chemistry and chromatographic properties of methacrylate‐ester‐based monolithic capillary columns via photografting
Authors: Eeltink Sebastiaan , Hilder Emily F. , Geiser Laurent , Svec Frantisek , Fréchet Jean M. J. , Rozing Gerard P. , Schoenmakers Peter J. , Kok Wim Th.
Published: February 2007

Preparation of monolithic capillary columns for separations in the CEC mode using UV‐initiated polymerization of the plain monolith followed by functionalization of its pore surface by photografting has been studied. The first step enabled the preparation of generic poly(butyl methacrylate‐co‐ethylene dimethacrylate) monoliths with optimized porous properties, controlled by the percentages of porogens 1‐decanol and cyclohexanol in the polymerization mixture, irradiation time, and UV light intensity. Ionizable monomers [2‐(methacryloyloxy)ethyl]trimethylammonium chloride or 2‐acryloamido‐2‐methyl‐1‐propanesulfonic acid were then photografted onto the monolithic matrix, allowing us to control the direction of the EOF in CEC. Different strategies were applied to control the grafting density and, thereby, the magnitude of the EOF. To control the hydrophobic properties, two approaches were tested: (i) cografting of a mixture of the ionizable and hydrophobic monomers and (ii) sequential grafting of the ionizable and hydrophobic monomers. Cografting resulted in similar retention but higher EOF. With sequential grafting, more than 50% increase in retention factors was obtained and a slight decrease in EOF was observed due to shielding of the ionizable moieties.
Elevated temperature–extended column length conventional liquid chromatography to increase peak capacity for the analysis of tryptic digests
Authors: Sandra Pat , Vanhoenacker Gerd
Published: February 2007

High efficiency separations (200 000 plates) were obtained on conventional LC equipment by coupling 8×25 cm×2.1 (or 4.6) mm id×5 μm dp ODS columns (total length 2 m) and operation at 60°C using a dedicated LC oven. The peak capacity in this 1‐D set‐up was 900 for the separation of human serum tryptic peptides analyzed after depletion of six highly abundant proteins. The chromatographic performance of an elevated temperature–extended column length conventional LC is highlighted.
Vanishing thetanull and hyperelliptic curves
Authors: Schneider Olivier
Published: February 2007

Let ℳ︁g,2 be the moduli space of curves of genus g with a level‐2 structure. We prove here that there is always a non hyperelliptic element in the intersection of four thetanull divisors in ℳ︁6,2. We prove also that for all g ≥ 3, each component of the hyperelliptic locus in ℳ︁g,2 is a connected component of the intersection of g – 2 thetanull divisors. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Exponential averaging for traveling wave solutions in rapidly varying periodic media
Authors: Matthies Karsten , Schneider Guido , Uecker Hannes
Published: February 2007

Reaction diffusion systems on cylindrical domains with terms that vary rapidly and periodically in the unbounded direction can be analyzed by averaging techniques. Here, using iterated normal form transformations and Gevrey regularity of bounded solutions, we prove a result on exponential averaging for such systems, i.e., we show that traveling wave solutions can be described by a spatially homogenous equation and exponentially small remainders. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Impairment of executive cognitive functioning in males with fragile X‐associated tremor/ataxia syndrome
Authors: Grigsby Jim , Brega Angela G. , Leehey Maureen A. , Goodrich Glenn K. , Jacquemont Sébastien , Loesch Danuta Z. , Cogswell Jennifer B. , Epstein Jennifer , Wilson Rebecca , Jardini Tristan , Gould Emma , Bennett Rachael E. , Hessl David , Cohen Susannah , Cook Kylee , Tassone Flora , Hagerman Paul J. , Hagerman Randi J.
Published: February 2007

The fragile X‐associated tremor/ataxia syndrome (FXTAS) is a recently identified phenotype associated with trinucleotide repeat expansions in the premutation range of the fragile X mental retardation 1 (FMR1) gene. In addition to progressive gait ataxia, action tremor, peripheral neuropathy, and parkinsonism, FXTAS involves impaired cognition. Our preliminary research suggests that executive cognitive functioning (ECF) is especially affected. In this study, a brief neuropsychological exam was administered to 33 men with FXTAS and 27 healthy controls. Compared with controls, individuals with FXTAS showed statistically significant impairments on measures from the Wechsler Adult Intelligence Scale, third edition (WAIS‐III; verbal IQ, performance [nonverbal] IQ, verbal comprehension, perceptual organization, and processing speed). FXTAS subjects scored significantly lower on three of four measures of ECF and on two tests of information processing speed. The results provide evidence that FXTAS involves impairment of general intellectual functioning, with marked impairment of executive cognitive abilities. The pattern of cognitive performance is somewhat similar to that observed in the frontal variant of frontotemporal dementia and several of the spinocerebellar ataxias, but differs from the deficits observed in dementia of the Alzheimer type. © 2007 Movement Disorder Society
Diagnostic criteria for psychosis in Parkinson's disease: Report of an NINDS, NIMH work group
Authors: Ravina Bernard , Marder Karen , Fernandez Hubert H. , Friedman Joseph H. , McDonald William , Murphy Diane , Aarsland Dag , Babcock Debra , Cummings Jefferey , Endicott Jean , Factor Stewart , Galpern Wendy , Lees Andrew , Marsh Laura , Stacy Mark , Gwinn‐Hardy Katrina , Voon Valerie , Goetz Christopher
Published: February 2007

There are no standardized diagnostic criteria for psychosis associated with Parkinson's disease (PDPsy). As part of an NIH sponsored workshop, we reviewed the existing literature on PDPsy to provide criteria that distinguish PDPsy from other causes of psychosis. Based on these data, we propose provisional criteria for PDPsy in the style of the Diagnostic and Statistical Manual of Mental Disorders IV‐TR. PDPsy has a well‐characterized temporal and clinical profile of hallucinations and delusions, which is different than the pattern seen in other psychotic disorders such as substance induced psychosis or schizophrenia. PDPsy is associated with a poor prognosis of chronic psychosis, nursing home placement, and death. Medications used to treat Parkinson's disease (PD) contribute to PDPsy but may not be sufficient or necessary contributors to PDPsy. PDPsy is associated with Lewy bodies pathology, imbalances of monoaminergic neurotransmitters, and visuospatial processing deficits. These findings suggest that PDPsy may result from progression of the disease process underlying PD, rather than a comorbid psychiatric disorder or drug intoxication. PDPsy is not adequately described by existing criteria for psychotic disorders. We established provisional diagnostic criteria that define a constellation of clinical features not shared by other psychotic syndromes. The criteria are inclusive and contain descriptions of the full range of characteristic symptoms, chronology of onset, duration of symptoms, exclusionary diagnoses, and associated features such as dementia. These criteria require validation and may be refined, but form a starting point for studies of the epidemiology and pathophysiology of PDPsy, and are a potential indication for therapy development. © 2007 Movement Disorder Society
Sleep‐related stridor due to dystonic vocal cord motion and neurogenic tachypnea/tachycardia in multiple system atrophy
Authors: Vetrugno Roberto , Liguori Rocco , Cortelli Pietro , Plazzi Giuseppe , Vicini Claudio , Campanini Aldo , D'Angelo Roberto , Provini Federica , Montagna Pasquale
Published: February 2007

Sleep‐disordered breathing and sleep‐related motor phenomena are part of the clinical spectrum of multiple system atrophy (MSA). Stridor has been attributed to denervation of laryngeal muscles or instead to dystonic vocal cord motion. We studied 3 patients with nocturnal stridor in the setting of MSA. All patients underwent nocturnal videopolysomnography (VPSG) with breathing and heart rate, O2 saturation and intra‐esophageal pressure recordings, and simultaneous EMG recordings of the posterior cricoarytenoid, cricothyroid, and thyroarytenoid muscles and continuous vocal cord motion evaluation by means of fiberoptic laryngoscopy. VPSG/EMG and fiberoptic laryngoscopy documented normal vocal cord motion without denervation during wake and stridor only during sleep when hyperactivation of vocal cords adductors appeared in the absence of significant O2 desaturation. All patients had tachycardia and tachypnea and paradoxical breathing during sleep, erratic intercostalis and diaphragmatic EMG activity and Rem sleep behavior disorder. One of the patients had restless legs syndrome with periodic limb movement during sleep and excessive fragmentary hypnic myoclonus. In conclusion, our patients with MSA had nocturnal stridor due to sleep‐related laryngeal dystonia. Stridor was associated with other abnormal sleep‐related respiratory and motor disorders, suggesting an impairment of homeostatic brainstem integration in MSA. © 2007 Movement Disorder Society
Different pattern of aquaporin‐4 expression in extensor digitorum longus and soleus during early development
Authors: Nicchia Grazia P. , Mola Maria G. , Pisoni Michela , Frigeri Antonio , Svelto Maria
Published: February 2007

Aquaporin‐4 (AQP4) is the neuromuscular water channel expressed at the sarcolemma of mammalian fast‐twitch fibers that mediates a high water transport rate, which is important during muscle activity. Clinical interest in the neuromuscular expression of AQP4 has increased as it is associated with the protein complex formed by dystrophin, the product of the gene affected in Duchenne muscular dystrophy. The expression of AQP4 during development has not been characterized. In this study, we analyzed the expression of AQP4 in extensor digitorum longus (EDL) and soleus, a fast‐ and slow‐twitch muscle, respectively, during the first weeks after birth. The results show that AQP4 expression in both types of skeletal muscle occurs postnatally. The time course of expression of AQP4 in the two types of muscles was also different. Whereas the expression of AQP4 protein levels in the EDL showed a progressive increase during the first month after birth, reaching levels found in adults by day 24, the levels of the protein in the soleus showed a transient peak between day 12 and day 24 and declined thereafter, an effect that may be related to the transient high number of fast motor units innervating the soleus muscle during this time. The results suggest that AQP4 expression in skeletal muscle is under neuronal influence and contribute to the understanding of the molecular events of fiber differentiation during development. Muscle Nerve, 2007
Post‐augmentation bladder perforation during urodynamic investigation
Authors: Blok Bertil F.M. , Al Zahrani Ahmed , Capolicchio John Paul , Bilodeau Claudette , Corcos Jacques
Published: February 2007

Aims

To report for the first time bladder rupture during filling cystometry many years after bladder augmentation.

Methods

A 17‐year‐old girl with T10 meningomyelocele had received an ileocystoplasty, continent catheterizable stoma, and bladder neck sling for neurogenic bladder dysfunction and intractable incontinence 8 years previously. She was continent with clean intermittent self‐catheterization four times per day. Yearly urodynamics showed a bladder capacity of up to 700 ml with good compliance and low bladder pressures. In March 2006, filling cystometry was performed.

Results

Bladder pressure was normal until 400 ml, after which it increased due to lower compliance. At 620 ml filling, the detrusor pressure was 52 cm H2O, and the patient complained suddenly of abdominal discomfort and bilateral shoulder pain, and the infusion was stopped. A catheter was placed and cystography showed intraperitoneal leakage along the left lateral bladder aspect and at the Mitrofanoff insertion site on the bladder dome. The perforations were closed via a midline incision and a ventriculoperitoneal shunt had to be exteriorized. There were no post‐operative complications and a control cystogram revealed no leakage.

Conclusions

Augmentation ileocystoplasty has been used extensively in order to increase bladder capacity and decrease intravesical pressure. Although spontaneous or traumatic perforation of the augmented bladder has been described previously, it was never reported in correlation with urodynamic investigation. Extreme caution is warranted in the face of decreased compliance during filling cystometry in these patients, even though urodynamics showed good bladder compliance and low bladder pressures many years after ileocystoplasty. Neurourol. Urodynam. 26:540–542, 2007. © 2007 Wiley‐Liss, Inc.
Modeling dynamic cerebral blood volume changes during brain activation on the basis of the blood‐nulled functional MRI signal
Authors: W. Wu Changwei , Liu Ho‐Ling , Chen Jyh‐Horng
Published: February 2007

Recently, vascular space occupancy (VASO) based functional magnetic resonance imaging (fMRI) was proposed to detect dynamic cerebral blood volume (CBV) changes using the blood‐nulled non‐selective inversion recovery (NSIR) sequence. However, directly mapping the dynamic CBV change by the NSIR signal change is based on the assumption of slow water exchange (SWE) around the capillary regime without cerebral blood flow (CBF) effects. In the present study, a fast water exchange (FWE) model incorporating with flow effects was derived from the Bloch equations and implemented for the quantification of dynamic CBV changes using VASO‐fMRI during brain activation. Simulated results showed that only subtle differences in CBV changes estimated by these two models were observed on the basis of previously published VASO results. The influence of related physiological and biophysical factors within typical ranges was evaluated in steady‐state simulations. It was revealed that in the transient state the CBV curves could be delayed in comparison with measured NSIR curves owing to the imbalance between the inflowing and outflowing blood signals. Copyright © 2007 John Wiley & Sons, Ltd.
On the possible ritual marking of a young XVIIIth dynasty pig skull from Tell el‐Amarna, Middle Egypt
Authors: Luff R. , Brothwell D.
Published: February 2007

A young pig skull, excavated from an ancient Egyptian village near Tell el‐Amarna, Middle Egypt, presents a number of unusual features which are suggestive of ante‐mortem human intervention with subsequent localised infection of the bone. Copyright © 2007 John Wiley & Sons, Ltd.
Investigation of bending modulus of fiber‐reinforced syntactic foams for sandwich and structural applications
Authors: Karthikeyan C. S. , Sankaran S. , Kishore
Published: February 2007

Polymer composite foams or syntactic foams containing 0.9, 1.76, 2.54, 3.54 and 4.5 vol% of E‐glass short fibers were processed and subjected to a three‐point bending test. The results show that the flexural modulus increased with fiber content, with the exception of 1.76% and 3.5% of fibers. This deviation was due to a higher void content for 1.76% and a non‐uniform distribution of fibers in the polymer composite foam system for 3.5%. However, in general, the incorporation of chopped strand fibers improved the flexural behavior of the syntactic foam system without much variation in density, thus making the reinforced syntactic foams act as improved core materials for sandwich and other structural applications. Copyright © 2007 John Wiley & Sons, Ltd.
In situ growth of interdigitated electrodes made of polypyrrole for active fiber composites
Authors: Pini Niccolò , Busato Stephan , Elsener Hans‐Rudolf , Ermanni Paolo
Published: February 2007

Active fiber composites are electromechanical actuators based on piezo‐ceramic fibers, which are embedded in a polymer matrix. The fibers are electrically contacted through so‐called interdigitated electrodes (IDEs). State‐of‐the‐art metallic IDEs only contact the fibers at two small sections of their circumference at the top and bottom of the composite ply, respectively. This paper presents an original technique to manufacture IDEs made of a conducting polymer (polypyrrole/p‐toluene sulfonic acid), where the polymer electrodes contact the fibers around their whole circumference. The necessary process steps are discussed, namely design of the master electrodes and electrochemical polymer growth with and without fibers. Processing issues are discussed and solutions are suggested. Copyright © 2007 John Wiley & Sons, Ltd.
Ethylene polymerisation by Ni–diphosphine azine complexes
Authors: Carvalho Maria Fernanda Nascimento Neves , Cermák Jan , Fernandes Anabela Catarino , Ferreira Ana Sofia , Galvão Adelino Moura , Matos Inês , Marques Maria Mercês
Published: February 2007

The properties of [NiX(PR2CH2C(But)NNC(But)CH2PR2)]+ complexes (where X = Br, and R = cyclohexyl (Cy), isopropyl (Pri), tert‐butyl (But), phenyl (Ph); X = Cl or I, and R = cyclohexyl) as catalysts for the polymerisation of ethylene were evaluated with or without the co‐catalysts methylaluminoxane (MAO), diethylaluminium chloride, trimethylaluminium or tri(isobutyl)aluminium. Their efficiency depends on the characteristics of the halogen (X) and the R group of the diphosphine azine ligand. Bromide (X) strongly enhances the catalytic properties of the complexes within the R order Cy > Pri > Ph > But. Temperature, co‐catalyst ratio (Al/Ni) and complex concentration also influence the catalytic activity. The best results were obtained with [NiBr{PCy2CH2C(But)NNC(But)CH2PCy2}]Br activated by MAO (A = 25.8 kg (mol Ni)−1 bar−1 h−1). The polymers were characterised using NMR and differential scanning calorimetry as branched polyethylenes, the number of branches increasing with the temperature of polymerisation. The molecular weights of the polymers were estimated using NMR. A proposal for the catalyst active precursor is made on the basis of experimental data and molecular orbital calculations. Copyright © 2007 Society of Chemical Industry
The glucose and nitrogen starvation response of Bacillus licheniformis
Authors: Voigt Birgit , Hoi Le Thi , Jürgen Britta , Albrecht Dirk , Ehrenreich Armin , Veith Birgit , Evers Stefan , Maurer Karl‐Heinz , Hecker Michael , Schweder Thomas
Published: February 2007

The glucose and nitrogen starvation stimulons of Bacillus licheniformis were determined by transcriptome and proteome analyses. Under both starvation conditions, the main response of B. licheniformis was a switch to the usage of alternative nutrient sources. This was indicated by an induction of genes involved in the metabolism of C‐2 substrates during glucose limitation. In addition, B. licheniformis seems to be using other organic substances like amino acids and lipids as carbon sources when subjected to glucose starvation. This observation is supported by the induction of a high number of genes coding for proteins involved in amino acid and lipid degradation. During nitrogen starvation, genes for several proteases and peptidases involved in nitrate and nitrite assimilation were induced, which enables this bacterium to recruit nitrogen from alternative sources. Both starvation conditions led to a down‐regulation of transcription of most vegetative genes, which was subsequently reflected by a reduced synthesis of the corresponding proteins. A selected set of genes was induced by both starvation conditions. Among them were yvyD, citA and the putative methylcitrate shunt genes mmgD, mmgE and yqiQ. However, both starvation conditions did not induce a general SigmaB‐dependent stress response.
Synthesis and characterization of a vinyl‐terminated benzoxazine monomer and its blends with poly(ethylene oxide)
Authors: Huang Jieh‐Ming , Kuo Shiao‐Wei , Lee Yuan‐Jyh , Chang Feng‐Chih
Published: February 2007

A vinyl‐terminated benzoxazine (VB‐a), which could be polymerized through ring‐opening polymerization, was synthesized through the Mannich condensation of bisphenol A, formaldehyde, and allylamine. This VB‐a monomer was then subjected to blending with poly(ethylene oxide) (PEO), followed by thermal curing, to form poly(VB‐a)/PEO blends. The specific interactions, miscibility, morphology, and thermal properties of these blends were investigated with Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry, dynamic mechanical analysis (DMA), and scanning electron microscopy (SEM). Before curing, we found that PEO was miscible with VB‐a, as evidenced by the existence of a single composition‐dependent glass transition temperature (Tg) for each composition. The FTIR spectra revealed the presence of hydrogen‐bonding interactions between the hydroxyl groups of poly(VB‐a) and the ether groups of PEO. Indeed, the ring‐opening reaction and subsequent polymerization of the benzoxazine were facilitated significantly by the presence of PEO. After curing, DMA results indicated that the 50/50 poly(VB‐a)/PEO blend exhibited two values of Tg: one broad peak appeared in the lower temperature region, whereas the other (at ca. 327 °C, in the higher temperature region) was higher than that of pristine poly(VB‐a) (301 °C). The presence of two glass transitions in the blend suggested that this blend system was only partially miscible. Moreover, SEM micrographs indicated that the poly(VB‐a)/PEO blends were heterogeneous. The volume fraction of PEO in the blends had a strong effect on the morphology. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 644–653, 2007
Illness stories on the internet: what do breast cancer patients want at the end of treatment?
Authors: Overberg R. I. , Alpay L. L. , Verhoef J. , Zwetsloot‐Schonk J. H. M.
Published: February 2007

The study aims to elicit user requirements for internet‐based applications disclosing fellow patients' illness stories for the benefit of breast cancer patients. Twenty‐six breast cancer patients, recruited via the Dutch Patient Organization for Breast Cancer, were interviewed about their preferences with regards to content, appearance, and search options concerning fellow patients' illness stories online. The interviews were analysed quantitatively (SPSS) and qualitatively (NVivo). Participants were mainly interested in fellow patients' experiences about how to cope with emotions, the impact of cancer in daily life, and physical discomforts. Most participants preferred a section of an illness story in text format about a specific topic; some of them wanted to be able to click on to the corresponding complete story, comprising of text alone or supported by voice or video clip. A majority of participants wanted to be able to select illness stories on the basis of several authors' features, i.e. treatment underwent, age, presence of metastases, time since diagnosis, and whether or not caring for children. Participants gave arguments for their preferences. The findings of this study will be used for designing an online trial with breast cancer patients aiming at refining the user requirements. Copyright © 2007 John Wiley & Sons, Ltd.
Modulated reflectivity probing of quantum dot and wetting layer states in InAs/GaInAsP/InP quantum dot laser structures
Authors: Sęk G. , Motyka M. , Kudrawiec R. , Misiewicz J. , Lelarge F. , Rousseau B. , Patriarche G.
Published: February 2007

InAs/GaInAsP quantum dot (QD) structure grown by gas source molecular beam epitaxy on InP (100) substrate and designed as an active region for laser applications at 1.55 μm wavelength range has been investigated by optical spectroscopy in order to probe its energy electronic structure. The advantages of the modulated reflectivity measurements (in a form of photoreflectance – PR) have been used to detect the optical transitions related to all relevant parts of the structure like cladding material, quaternary barriers, wetting layer and finally quantum dots. Our theoretical analysis based on effective mass approximation calculations has shown that two high energy PR features above the QD ground state emission are related to heavy hole and light hole ground state transitions in the InAs wetting layer which is 3–4 monolayers thick. Moreover, the confinement potential for the dots is shallow enough to confine one electron state only and hence a single QD heavy hole transition has been observed in PR. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electromodulation spectroscopy of interband transitions in GaInNAsSb/GaAs quantum wells with high indium content
Authors: Kudrawiec R. , Yuen H. B. , Bank S. R. , Bae H. P. , Wistey M. A. , Harris James S. , Motyka M. , Gladysiewicz M. , Misiewicz J.
Published: February 2007

Contactless electroreflectance (CER) has been applied to study the optical transitions in as‐grown and annealed GaInNAsSb/GaAs QWs with 2.25% of nitrogen, high indium content (34%) and antimony flux varied from zero to 1.0 × 10–7 beam equivalent pressure torr (it corresponds to antimony content varied from 0 to 2%). It has been observed that broadening of the CER resonance related to the ground state transition decreases about three times (from ∼60 meV to 20 meV) after the incorporation of antimony into GaInNAs/GaAs QWs. Moreover, it has been found that the broadening parameter does not decrease with the rise of antimony content from 0.5% to 2.0%. It means that only 0.5% Sb is enough to improve the optical quality of GaInNAs/GaAs QWs. In addition, it has been observed that post growth annealing significantly improves the optical quality of these QWs and shifts to blue all QW transitions. By matching the QW transition energies with those obtained from theoretical calculations performed within the effective mass approximation the conduction band offset in these QWs has been found to be close to 80%. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photo‐ and electro‐reflectance spectroscopy of δ‐doped GaAs/AlAs multiple quantum well structures
Authors: Čechavičius B. , Kavaliauskas J. , Krivaitė G. , Valušis G. , Seliuta D. , Halsall M. P. , Harrison P.
Published: February 2007

The photoreflectance (PR) and contactless electroreflectance (CER) spectroscopies have been used to study optical transitions, electronic structure and internal electric fields in beryllium δ‐doped GaAs/AlAs multiple quantum wells (MQWs) designed for terahertz sensors. QW widths ranged from 3 to 20 nm while doping densities varied from 2 × 1010 to 2.5 × 1012 cm–2. From the Franz–Keldysh oscillations in PR and CER spectra the surface electric field strength was established. The optical spectra were found to exhibit excitonic behaviour up to acceptor density of 2.5 × 1012 cm–2. The origin of spectral features was identified on a basis of their dependence on optical bias and calculations of electronic structure under electric field. Modulation spectra of lightly doped samples were found to be dominated by symmetry‐allowed excitonic transitions while in highly doped samples additional features associated with symmetry forbidden transitions, coming into play due to internal electric field, were revealed. Selective detection of terahertz radiation by sensors based on the studied structures is demonstrated. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modulation spectroscopy of AlGaN/GaN heterostructures: The influence of electron–hole interaction
Authors: Goldhahn R. , Winzer A. T. , Dadgar A. , Krost A. , Weidemann O. , Eickhoff M.
Published: February 2007

The present special issue of physica status solidi (a) contains contributions from the 2nd International Workshop on Modulation Spectroscopy of Semiconductor Structures (MS3), held in Wrocław, Poland, 29 June–1 July 2006.

Editor's Choice is the article by R. Goldhahn et al. [1] which reports a detailed analysis of electroreflectance (ER) spectra for AlGaN/GaN heterostructures containing a two‐dimensional electron gas (2DEG). The cover picture depicts a color‐converted bias voltage map of the ER spectra around the GaN band gap recorded at a temperature of 5 K. The dark‐red color corresponds to a ΔR /R signal of 3 × 10–2. The Burstein–Moss (BM) shift and the position of the first Franz–Keldysh oscillation (FKO) are indicated.

Rüdiger Goldhahn's research focuses on the further development of modulation spectroscopy methods for the characterization of bulk semiconductors and low‐dimensional systems. Andreas T. Winzer investigated the electro‐optical properties of III‐nitride heterostructures and is currently engaged in the solar cell production at Ersol Thin Film GmbH. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Preface: phys. stat. sol. (a) 204/2
Authors: Misiewicz Jan , Sitarek Piotr
Published: February 2007

The first International Workshop on Modulation Spectroscopy of Semiconductor Structures (MS3) in Wrocław (in the southwest part of Poland) at the beginning of July 2004 gathered almost 40 participants, half of them from abroad. This fruitful meeting resulted in a special issue of physica status solidi (a), Vol. 202, No. 7 (2005).

The second meeting of scientists involved in all aspects of modulation spectroscopy of semiconductors, semiconductor heterostructures and devices – the 2nd MS3 Workshop – was organized at the same place (Wrocław, Poland) and almost at the same time of the year in 2006.

The MS3 Workshop became a forum of discussion on the advantages of photoreflectance, electroreflectance, contactless electroreflectance, thermoreflectance, differential reflectance and wavelength‐modulated surface photovoltage spectroscopy. Applications of the above methods to investigate transistor, diode and laser structures including VCSELs, low‐dimensional structures of both wings of the spectrum, i.e. wide band gap materials like GaN, AlGaN and low band gap materials such as GaInN(Sb)As, InGaAs were demonstrated. A lot of time was also devoted to modulation spectroscopy of quantum dot structures.

It is our great pleasure to publish the most interesting MS3 workshop presentations again in this special issue of physica status solidi (a).

The organizers acknowledge the financial support of the Workshop by Wrocław University of Technology and the Foundation for Polish Science. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A study of cold fronts over the British Isles
Authors: Sansom H. W.
Published: February 2007

Fifty cold fronts are classified by means of two simultaneous aerological soundings. Two general categories are found:

Those in which the warm air is descending, usually forming a subsidence inversion. The name Katafront (following Bergeron) is applied to such fronts.

Fronts at which the warm air is ascending. These, which are named Anafronts, usually show no sharp discontinuity on a tephigram.

The two types of cold front give rise to quite different weather conditions. The changes in wind and temperature are generally much more abrupt at an anafront, where there is also much more precipitation. A katafront frequently brings a rapid clearance followed by fine weather.

The variation of wind with height through the front is markedly different at the two types, the chief characteristics being:

Anafront: Rapid backing of wind with height; the component normal to the front decreases. The upper winds are inclined at a small angle (about 15°) to the line of the front.

Katafront: Slight backing with height; the normal component increases considerably. The upper winds are inclined at a large angle (about 40°) to the front. Consideration of the horizontal wind changes across the front leads to the expectation of troughs with strong cyclonic shear at anafronts, and the more rapid occlusion of katafronts.

Anafronts and katafronts are generally associated with different stages in the history of a cold front; an anafront is normally the initial state, but develops into a katafront later as the depression becomes more occluded. Katafronts are the more common type in this country, especially in summer.

Calculations of the mean slope above the friction layer give values of about 1/70 for anafronts, and 1/300 for katafronts. The vertical velocity of the warm air at an anafront is of the order of 10 cm/sec upwards, while at a katafront it is about 2.5 cm/sec downwards. Vertical cross‐sections of wet‐bulb potential temperature show that there is often latent or convective instability at the nose of a katafront. This may be the explanation of the large ascending velocities found in this region by sailplane pilots.
Theory of airflow over mountains: IV‐separation of flow from the surface
Authors: Scorer R. S.
Published: February 2007

Separation of flow may be two‐dimensional when the wake or eddy is closed, or three‐dimensional when the air is continuously replaced. It often occurs at a salient edge. When it occurs the effect of the mountain on the high‐level flow is reduced. If the airflow is temporarily induced to follow the ground in an airstream favourable to separation, very large vertical velocities may result. Eddies may be shed periodically from the lee slope of a ridge. Lee waves inhibit separation and so do katabatic winds and downdraughts in heavy rain. Convection makes it more likely over lee slopes but inhibits it at the top of windward slopes.
Ice‐crystal counts and the freezing of water drops
Authors: Bigg E. K.
Published: February 2007

An analysis of the concentrations of ice crystals observed in a cold box by Smith and Heffernan (1954) in the course of 155 measurements is shown to provide support for values calculated for a given temperature from an equation used by Bigg (1953), thus verifying the analogy between freezing of airborne droplets and freezing of drops suspended in an insoluble liquid.
Fog precipitation on table mountain
Authors: Nagel J. F.
Published: February 2007

Fog precipitation on Table Mountain has been measured over a period of one year by means of two raingauges, one of which was equipped with a fog‐catcher. The evaluation of the records is complicated by the uncertainty of the fog precipitation during rain and drizzle. It is shown that satisfactory results can be obtained if at least two sets of instruments are installed on the mountain, one of them in the middle of the plateau and the other some 200 m lower.

The fog precipitation for the year on the plateau was found to be 3,294 mmandthe rainfallto be 1,940 mm. The mean intensity of rainfall was 1.84 mm/hr and that of fog precipitation 3.75 mm/hr. Although the latter appears to be rather high, it is much lower than the value obtained theoretically. T h e discrepancy is accounted for by several errors in the measurements, which are discussed, and by fog precipitation supposed to occur on the slopes, which causes the air to reach the plateau with a smaller liquid‐water content than calculation indicates.
Theory of mountain waves of large amplitude
Authors: Scorer R. S. , Klieforth H.
Published: February 2007

Rotors are defined as regions containing flow in the opposite direction to the main stream and are shown to exist when the wave amplitude is large enough. Equations are derived for computing rotor flow in an infinitely deep atmosphere.

The problem of choosing an appropriate second boundary condition in steady flow over a ridge is complicated when the amplitude is finite because the shape of obstacle obtained depends on the airstream characteristics as well as upon the mathematical form given to it. Probably under some actual conditions the oncoming airstream is modified by the presence of the mountain.

Because of the great variety of airstreams and mountains no general case can be illustrated. The particular cases chosen illustrate rotor flow. These particular cases do, however, each represent a set of cases in which all the non‐dimensional numbers involved have the same value.

Known cases of rotors in the Sierra Nevada and at Cross Fell are cited to illustrate the theory.
Measured radiative flux divergence near the ground at night
Authors: Funk J. P.
Published: February 2007

Nocturnal radiative flux divergence profiles in the lowest few metres have been directly measured and typical cases are presented in graphical form.

Comparison of flux divergence calculated from radiation charts with measured divergence between 0·5 m and 1·5 m for a wide range of wind speeds and cloud conditions has shown the measured value to be up to 2·8 times larger than the calculated one. This discrepancy and others are attributed to the presence of haze.

Since radiative cooling rates were generally found to be higher than actual rates, development of the nocturnal inversion near the surface is shown to be predominantly caused by radiation, with eddy cooling supplanted in the lowest layers by eddy warming.

Periods of radiative warming sometimes associated with long‐period (40 min) air‐temperature fluctuations were found. A possible explanation is given for these and for fog formation in airlayers not in direct contact with the surface.

Comparisons are given between radiative ground temperatures and those obtained from standard grass thermometers.
The expansion of clusters of particles in the atmosphere
Authors: Smith F. B. , Hay J. S.
Published: February 2007

In this paper, the problem of the spatial expansion of a cluster of particles under the action of turbulence is investigated. The basic difficulty, that this form of diffusion depends on the Lagrangian properties of the turbulent field, is met by the assumption that the Lagrangian and Eulerian time‐correlograms are functionally similar. In consequence, it is possible to solve the equation governing the cluster's expansion to give prediction laws expressed only in terms of easily measured parameters of the turbulence. The application of the full solution is lengthy but a simple working approximation follows from the fact that over an important part of the expansion at which the size of the cluster is of the same order of magnitude as the Eulerian length‐scale, the rate of expansion is approximately constant and is proportional to the square of the intensity of turbulence whilst independent of the length scale itself. Experiments to test these formulae have been carried out on the diffusion of clusters of Lycopodium spores over a few hundred metres downwind travel near the ground, and the diffusion of long crosswind clouds of aircraft‐released fluorescent particles, sampled along the vertical, after several kilometres travel in the free atmosphere. Whilst the experiments are few in number and the conditions often did not strictly conform to the conditions of isotropy and homogeneity required by the theory, the results are satisfactorily consistent with the prediction formulae and imply an effectively constant ratio between the scales of the Lagrangian and Eulerian time‐correlograms.
Natural convection in the earth's boundary layer
Authors: Townsend A. A.
Published: February 2007

The relation between the vertical distributions of mean temperature in buoyant convection over a horizontal surface as observed in the atmosphere and in the laboratory is examined. Some measurements by Webb, obtained in conditions of strong instability, are analysed and shown to be consistent with three distinct regions of flow, distinguished by their heat‐transfer characteristics. They are:

a region of forced convection with temperature gradient inversely proportional to height (negative Richardson number less than 0·02);

a region of mixed (or free) convection with temperature gradient inversely proportional to the 4/3‐power of the height (negative Richardson number between 0·03 and 1·0) and

a region of natural convection with temperature gradient inversely proportional to the square of the height (negative Richardson number greater than 1·0).

Reasons for the existence and properties of the last two regions are discussed briefly.
Some observed properties of medium‐scale diffusion in the atmosphere
Authors: Pasquill F.
Published: February 2007

Diffusion experiments using fluorescent particles are described and data on travel and horizontal spread over distances 10 to 80 miles are summarized.

Good vertical mixing evidently counteracts the tendency for a cloud of particles to be sheared according to the wind profile. The effective velocity of the cloud is then close to the mean velocity through the layer of mixing, but some unexplained discrepancies in direction have been encountered. The shearing which can occur in the absence of vertical mixing will become effective as a horizontal spread through the action of subsequent vertical mixing.

The data are insufficient to allow any general conclusion to be reached about the relative importance of horizontal turbulence and vertical shear in promoting horizontal spread.
Radiative transport properties of fogs
Authors: Brinkworth B. J.
Published: February 2007

All clean fogs exhibit a common gross‐phase function for scattering when the mean‐square particle size is large enough to produce non‐selectivity with respect to the wavelengths of the radiation. Then the transport mean free path varies only with the attenuation coefficient for single scattering and is shown to be approximately equal to the daytime visual range, as given by Koschmieder's relation.