bluuebunny/crossref_metadata_2025 huggingface dataset:
Sarcoidosis Presenting as a Proximal Phalangeal Bony Swelling—A Case and Review of the Literature
Authors: Duckworth Andrew D. , Hill Adam T. , Beggs Ian , Patton James T. , Salter Donald M. , Porter Daniel E.
Published: June 2009

We report a case of a 27-year-old man who presented with a progressive painful swelling at the base of his left index finger, with radiographs and a computed tomography scan revealing a lytic lesion of the proximal phalanx. Following further investigation, the patient underwent a bone biopsy that revealed a florid noncaseating granulomatous chronic inflammatory infiltrate, compatible with sarcoidosis. Osseous sarcoidosis of the hand is uncommon and, in the absence of significant systemic disease, is rarely the primary presenting feature. Early diagnosis and treatment of such undetermined bone pathology, via referral to a regional musculoskeletal tumor service, can prevent significant future complications.
Dating and disclosure: Adolescent management of information regarding romantic involvement
Authors: Daddis Christopher , Randolph Danielle
Published: June 2009

Voluntary disclosure regarding romantic involvement was examined in a sample of 222 middle and late adolescents (124 female adolescents, M = 16.19 years). Disclosure was described with three empirically derived, conceptually meaningful composites that pertained to identity/choice of romantic partner, everyday expression of romantic relationship, and parental supervision/sexual contact. Disclosure regarding identity/choice and expression was greater for females than for males and mothers were targets more than were fathers. Older adolescents disclosed less regarding supervision/sex than did younger adolescents. Trust was positively associated with disclosure, particularly for females when considering supervision issues. Assessment of adolescents' beliefs regarding act's potential for self‐harm and consequences to others illuminated adolescents' reasoning regarding disclosure and nondisclosure. Potential harm was positively associated with disclosure regarding supervision/sex issues. The potential for an activity to affect other people was positively associated with disclosure regarding identity/choice and expression for middle adolescents but not for late adolescents.
Random data Cauchy problem for supercritical Schrödinger equations
Authors: Thomann Laurent
Published: June 2009

In this paper we consider the Schrödinger equation with power-like nonlinearity and confining potential or without potential. This equation is known to be well-posed with data in a Sobolev space

\mathcal{H}^{s}

if

s

is large enough and strongly ill-posed is

s

is below some critical threshold

s_{c}

. Here we use the randomisation method of the inital conditions, introduced by N. Burq and N. Tzvetkov, and we are able to show that the equation admits strong solutions for data in

\mathcal{H}^{s}

for some

s < s_{c}

.

Dans cet article on s'intéresse à l'équation de Schrödinger avec non-linéarité polynômiale et potentiel confinant ou sans potentiel. Cette équation est bien posée pour des données dans un espace de Sobolev

\mathcal{H}^{s}

si

s

est assez grand, et fortement instable si

s

est sous un certain seuil critique

s_{c}

. Grâce à une randomisation des conditions initiales, comme l'ont fait N. Burq et N. Tzvetkov, on est capable de construire des solutions fortes pour des données dans

\mathcal{H}^{s}

avec des

s < s_{c}

.
Segmenting Stakeholders in Terms of Corporate Responsibility: Implications for Reputation Management
Authors: Hillenbrand Carola , Money Kevin
Published: June 2009

Corporate Responsibility is a concept that is receiving increasing attention in the Corporate Reputation literature. Many researchers have sought to link high levels of Corporate Responsibility with good Corporate Reputations. Yet, the link between these two concepts is not clear and managers do not have much guidance on how they could embrace Corporate Responsibility to enhance Corporate Reputation. One potential reason for the current confusion is that stakeholders have, for the most part, been considered as being homogenous in terms of their expectations of Corporate Responsibility, which means reputational impact is difficult to define. This paper challenges the notion that Corporate Responsibility is an homogenous construct. A latent class model is used to provide evidence that customers and employees of a financial service organisation can be segmented into three groups. This suggests that these groups have different expectations of Corporate Responsibility and as such positive reputation is likely to be driven by meeting these different sets of expectations. The understanding of how Corporate Responsibility impacts on Corporate Reputation is heightened and further implications for the management of reputation and directions for future research are discussed.
Increasing use of opioids from 2004 to 2007 – Pharmacoepidemiological data from a complete national prescription database in Norway
Authors: Fredheim Olav Magnus S. , Skurtveit Svetlana , Breivik Harald , Borchgrevink Petter C.
Published: June 2009

Background: A high opioid consumption for cancer related and acute pain may indicate adequate pain treatment. Analysis of a national, compulsory and complete database of all dispensed prescription drugs in Norway (NorPD) may reveal important epidemiological data on prescription pattern of opioids. This study investigated the prevalence of opioid dispensions in 2004–2007 and explored patterns of use.

Methods: All pharmacies in Norway submit data electronically to NorPD on all dispensed prescriptions. All prescriptions to any individual are identified by a unique pseudonym. All persons who were dispensed opioids from 2004 to 2007 are included in the study. Cancer patients are identified by a reimbursement code. Non‐cancer pain indications are inferred from pattern of prescriptions.

Results: 470,638 Norwegians were dispensed opioids in 2007, corresponding to 9.7% of the population (13.0% of adults). Only 13,220 persons (2.8% of all patients) received opioids for cancer pain, accounting for 10% of all dispensed opioids measured in defined daily doses (DDDs). Among persons with non‐cancer pain 77% received only one dispension per year or less than 50 DDDs/year. Fifteen percent received from 50 to 200 DDDs/year. Only 13,846 (4%) received >400 DDDs/year and are likely to be daily users for chronic non‐cancer pain. From 2004 to 2007 a 9 % increase was observed in the number of persons receiving opioids and the number of dispensions, whereas opioid types, doses, and indications appeared stable.

Interpretation: From these prescription patterns it can be concluded that the majority of patients received opioids for acute, non‐cancer pain.
At the crossroads of polarity, proliferation and apoptosis: The use of Drosophila to unravel the multifaceted role of endocytosis in tumor suppression
Authors: Vaccari Thomas , Bilder David
Published: June 2009

Endocytosis is an important regulator of cell–cell signaling and endocytic trafficking has been increasingly implicated in control of tumor suppression. Recent insights from Drosophila indicate that impairment of multiple trafficking steps which lead to receptor degradation can cause tumor formation in epithelial organs. These tumors are characterized by sustained activation of a number of mitogenic signaling pathways, and by subversion of epithelial polarity and the apoptotic response. Cooperation between such alterations, as well as tumor–host interactions, is also observed. The recapitulation of several hallmarks of human cancers in fly tumors provides a framework to understand the role of defective endocytosis in cancer.
The use of visual analogue scales to assess motivation to eat in human subjects: a review of their reliability and validity with an evaluation of new hand-held computerized systems for temporal tracking of appetite ratings
Authors: Stubbs R. J. , Hughes D. A. , Johnstone A. M. , Rowley E. , Reid C. , Elia M. , Stratton R. , Delargy H. , King N. , Blundell J. E.
Published: June 2009

This present paper reviews the reliability and validity of visual analogue scales (VAS) in terms of (1) their ability to predict feeding behaviour, (2) their sensitivity to experimental manipulations, and (3) their reproducibility. VAS correlate with, but do not reliably predict, energy intake to the extent that they could be used as a proxy of energy intake. They do predict meal initiation in subjects eating their normal diets in their normal environment. Under laboratory conditions, subjectively rated motivation to eat using VAS is sensitive to experimental manipulations and has been found to be reproducible in relation to those experimental regimens. Other work has found them not to be reproducible in relation to repeated protocols. On balance, it would appear, in as much as it is possible to quantify, that VAS exhibit a good degree of within-subject reliability and validity in that they predict with reasonable certainty, meal initiation and amount eaten, and are sensitive to experimental manipulations. This reliability and validity appears more pronounced under the controlled (but more artificial) conditions of the laboratory where the signal: noise ratio in experiments appears to be elevated relative to real life. It appears that VAS are best used in within-subject, repeated-measures designs where the effect of different treatments can be compared under similar circumstances. They are best used in conjunction with other measures (e.g. feeding behaviour, changes in plasma metabolites) rather than as proxies for these variables. New hand-held electronic appetite rating systems (EARS) have been developed to increase reliability of data capture and decrease investigator workload. Recent studies have compared these with traditional pen and paper (P&P) VAS. The EARS have been found to be sensitive to experimental manipulations and reproducible relative to P&P. However, subjects appear to exhibit a significantly more constrained use of the scale when using the EARS relative to the P&P. For this reason it is recommended that the two techniques are not used interchangeably.
DEALING WITH CHINA'S FUTURE POPULATION DECLINE: A PROPOSAL FOR REPLACING LOW BIRTH RATES WITH SUSTAINABLE RATES
Authors: CAO SHIXIONG , WANG XIUQING
Published: June 2009

Decreasing population levels due to declining birth rates are becoming a potentially serious social problem in developed and rapidly developing countries. China urgently needed to reduce birth rates so that its population would decline to a sustainable level, and the family planning policy designed to achieve this goal has largely succeeded. However, continuing to pursue this policy is leading to serious, unanticipated problems such as a shift in the country's population distribution towards the elderly and increasing difficulty supporting that elderly population. Social and political changes that promoted low birth rates and the lack of effective policies to encourage higher birth rates suggest that mitigating the consequences of the predicted population decline will depend on a revised approach based on achieving sustainable birth rates.
Irrationality measures for some automatic real numbers
Authors: ADAMCZEWSKI BORIS , RIVOAL TANGUY
Published: June 2009

This paper is devoted to the rational approximation of automatic real numbers, that is, real numbers whose expansion in an integer base can be generated by a finite automaton. We derive upper bounds for the irrationality exponent of famous automatic real numbers associated with the Thue–Morse, Rudin–Shapiro, paperfolding and Baum–Sweet sequences. These upper bounds arise from the construction of some explicit Padé or Padé type approximants for the generating functions of these sequences. In particular, we prove that the Thue–Morse–Mahler numbers have an irrationality exponent at most equal to 4. We also obtain an explicit description of infinitely many convergents to these numbers.
Investigating dynamical complexity in the magnetosphere using various entropy measures
Authors: Balasis Georgios , Daglis Ioannis A. , Papadimitriou Constantinos , Kalimeri Maria , Anastasiadis Anastasios , Eftaxias Konstantinos
Published: June 2009

The complex system of the Earth's magnetosphere corresponds to an open spatially extended nonequilibrium (input‐output) dynamical system. The nonextensive Tsallis entropy has been recently introduced as an appropriate information measure to investigate dynamical complexity in the magnetosphere. The method has been employed for analyzing Dst time series and gave promising results, detecting the complexity dissimilarity among different physiological and pathological magnetospheric states (i.e., prestorm activity and intense magnetic storms, respectively). This paper explores the applicability and effectiveness of a variety of computable entropy measures (e.g., block entropy, Kolmogorov entropy, T complexity, and approximate entropy) to the investigation of dynamical complexity in the magnetosphere. We show that as the magnetic storm approaches there is clear evidence of significant lower complexity in the magnetosphere. The observed higher degree of organization of the system agrees with that inferred previously, from an independent linear fractal spectral analysis based on wavelet transforms. This convergence between nonlinear and linear analyses provides a more reliable detection of the transition from the quiet time to the storm time magnetosphere, thus showing evidence that the occurrence of an intense magnetic storm is imminent. More precisely, we claim that our results suggest an important principle: significant complexity decrease and accession of persistency in Dst time series can be confirmed as the magnetic storm approaches, which can be used as diagnostic tools for the magnetospheric injury (global instability). Overall, approximate entropy and Tsallis entropy yield superior results for detecting dynamical complexity changes in the magnetosphere in comparison to the other entropy measures presented herein. Ultimately, the analysis tools developed in the course of this study for the treatment of Dst index can provide convenience for space weather applications.
Moho depth and Vp/Vs ratio in peninsular Italy from teleseismic receiver functions
Authors: Piana Agostinetti N. , Amato A.
Published: June 2009

We present a new data set of Moho depth estimates for peninsular Italy, obtained from receiver functions analysis and a grid search approach. Teleseismic records from 174 broadband seismic stations were used to compute the receiver function data set. In general, our results agree well with previous knowledge, adding original information in many regions where previous data were lacking or uncertain. We find broad regions with consistent Moho depth, namely, (1) the peri‐Tyrrhenian areas bordering the homonymous sea have a 20 to 25 km deep Moho; (2) the foreland regions (Adriatic, Apulia, Iblean) with 30–35 km deep Moho; (3) the Apennines belt, where we find westward deepening of the Adriatic Moho down to 50 km depth, that well delineate the westward Adria subduction, overlayed by the shallow Tyrrhenian Moho; (4) Calabria shows a flat, 40 km deep Moho suddenly dipping at high angle from the Tyrrhenian coast westward, defining the Ionian subduction; and (5) a clear separation between northern and southern Apennines is marked by a region of almost flat Moho, possible evidence of a detached slab in between. We also find that in the northern Apennines the shallow Tyrrhenian Moho is continuous for more than 200 km from the sea to under the northern Apennines, with a generally flat geometry and a few undulations suggesting either the “boudinage” or episodic pulses of extension of the Tyrrhenian crust during its Pliocene‐Quaternary stretching. The eastward extent of the Tyrrhenian Moho below the Apenninic belt approximately corresponds to the eastward extent of the observed extension in the upper crust as mapped by the normal faulting earthquakes. In this portion of the Apennines, we interpret an intracrustal discontinuity, SW dipping below the belt parallel to the Adria Moho, as the top of the lower crust being subducted beneath the Apennines. The “subcrustal” earthquakes of this region (down to 80 km depth) seem to be located within this subducted crustal layer. The southern Apennines show the same general geometry of subduction as the northern arc, although the former have a less defined on‐land extended region and no earthquakes in the lower crust–uppermost mantle. In between, the central Apennines present a different Moho geometry: no clear doubling of the two plates but rather a constant bilateral deepening possibly associated to a crustal root, with no evidence of a subduction setting. This reinforces the hypothesis of a detached slab in this area. We also present the first large‐scale mapping of average crustal Vp/Vs ratios for peninsular Italy. The results, although representing averages over the whole crust, enhance some interesting features. The most evident are belts of high Vp/Vs in the thinned crust of the Apennines where extension has long been active in the Quaternary, probably as an effect of highly fractured rocks with abundant fluid circulation. Strong correlation exists between areas of high Vp/Vs and Quaternary volcanoes, suggesting the presence of fluids at depth.
Effects of biologically induced differential heating in an eddy‐permitting coupled ocean‐ecosystem model
Authors: Löptien Ulrike , Eden Carsten , Timmermann Axel , Dietze Heiner
Published: June 2009

On the basis of integrations of an eddy‐permitting coupled physical‐biological model of the tropical Pacific we explore changes in the simulated mean circulation as well as its intraseasonal to interannual variability driven by the biologically modulated vertical absorption profiles of solar radiation. Three sensitivity ocean hind‐cast experiments, covering the period from 1948 to 2003, are performed. In the first one, simulated chlorophyll affects the attenuation of light in the water column, while in the second experiment, the chlorophyll concentration is kept constant in time by prescribing an empirically derived spatial pattern. The third experiment uses a spatially and temporally constant value for the attenuation depth. The biotically induced differential heating is generated by increased absorption of light in the surface layers, leading to a surface warming and subsurface cooling. The effect is largest in the eastern equatorial Pacific. However, the initial vertical redistribution of heat leads to considerable changes of the near‐surface ocean circulation subsequently influencing the near‐surface temperature structure. In general, including biophysical coupling improves the model performance in terms of temperature and ocean circulation patterns. In particular, the upwelling in the eastern equatorial Pacific is enhanced, the mixed layer becomes shallower, the warm bias in the eastern Pacific is reduced, and the zonal temperature gradient increases. This leads to stronger La Niña events and an associated increase in the variability of the Niño3 SSTA time series. Furthermore, the eddy kinetic energy (EKE) associated with mesoscale eddies in the eastern equatorial Pacific increases by almost 100% because of enhanced EKE production due to enhanced horizontal and vertical shear of the mean currents.
Suspended sediment and carbonate transport in the Yukon River Basin, Alaska: Fluxes and potential future responses to climate change
Authors: Dornblaser Mark M. , Striegl Robert G.
Published: June 2009

Loads and yields of suspended sediment and carbonate were measured and modeled at three locations on the Yukon, Tanana, and Porcupine Rivers in Alaska during water years 2001–2005 (1 October 2000 to 30 September 2005). Annual export of suspended sediment and carbonate upstream from the Yukon Delta averaged 68 Mt a−1 and 387 Gg a−1, respectively, with 50% of the suspended sediment load originating in the Tanana River Basin and 88% of the carbonate load originating in the White River Basin. About half the annual suspended sediment export occurred during spring, and half occurred during summer‐autumn, with very little export in winter. On average, a minimum of 11 Mt a−1 of suspended sediment is deposited in floodplains between Eagle, Alaska, and Pilot Station, Alaska, on an annual basis, mostly in the Yukon Flats. There is about a 27% loss in the carbonate load between Eagle and Yukon River near Stevens Village, with an additional loss of about 29% between Stevens Village and Pilot Station, owing to a combination of deposition and dissolution. Comparison of current and historical suspended sediment loads for Tanana River suggests a possible link between suspended sediment yield and the Pacific decadal oscillation.
Effects of land use changes on streamflow generation in the Rhine basin
Authors: Hurkmans R. T. W. L. , Terink W. , Uijlenhoet R. , Moors E. J. , Troch P. A. , Verburg P. H.
Published: June 2009

The hydrological regime of the Rhine basin is expected to shift from a combined snowmelt‐rainfall regime to a more rainfall‐dominated regime because of climate change, leading to more extreme flood peaks and low flows. Land use changes may reinforce the effects of this shift through urbanization or may counteract them through, for example, afforestation. In this study, we investigate the effect of projected land use change scenarios on river discharge. Sensitivity of mean and extreme discharge in the Rhine basin to land use changes is investigated at various spatial scales. The variable infiltration capacity (VIC) (version 4.0.5) model is used for hydrological modeling forced by a high‐resolution atmospheric data set spanning the period 1993–2003. The model is modified to allow for bare soil evaporation and canopy evapotranspiration simultaneously in sparsely vegetated areas, as this is more appropriate for simulating seasonal effects. All projected land use change scenarios lead to an increase in streamflow. The magnitude of the increase, however, varies among subbasins of different scales from about 2% in the upstream part of the Rhine (about 60,000 km2) to about 30% in the Lahn basin (about 7000 km2). Streamflow at the basin outlet proved rather insensitive to land use changes because over the entire basin affected areas are relatively small. Moreover, projected land use changes (urbanization and conversion of cropland into (semi)natural land or forest) have opposite effects. At smaller scales, however, the effects can be considerable.
Frost flower formation on sea ice and lake ice
Authors: Style Robert W. , Worster M. Grae
Published: June 2009

Frost flowers are clusters of ice crystals found on freshly formed sea ice and occasionally on frozen lakes. They belong to a class of vapour‐related phenomena that includes freezing fog, hoar frost and dew. It has hitherto been supposed that they form by condensation from a supersaturated atmosphere or from water wicked up through porous sea ice. Here we show that they can form on solid, pure ice sublimating into an unsaturated atmosphere. We derive a general regime diagram showing the atmospheric conditions under which the different vapour‐related phenomena occur and confirm our predictions of frost‐flower formation with a series of laboratory experiments. Our results can be used in climate models to predict occurrence of frost flowers, which significantly enhance albedo and provide the substrate for chemical production of ozone‐depleting bromine monoxide, and in paleo‐climate reconstructions by relating observations of sea‐salt aerosols in ice cores to atmospheric conditions.
Three-Dimensional Power Doppler Analysis of Cerebral Circulation in Normal and Growth-Restricted Fetuses
Authors: Bartha Jose L , Moya Eva M , Hervías-Vivancos Blas
Published: June 2009

The objective of the present study was to evaluate fetal cerebral circulation by using three-dimensional (3D) power Doppler ultrasound in normal and growth-restricted fetuses. A total of 100 normal grown fetuses were compared with other 25 with growth restriction (FGR). Three-dimensional power Doppler ultrasound was used to assess fetal cerebral 3D vascular indices: vascularization index, flow index (FI), and vascularization flow index (VFI). Both FI and VFI correlated positively with gestational age. On average, all the 3D vascular indices were increased in fetuses with FGR. The proportion of fetuses detected as having hemodynamic redistribution was higher when using 3D power Doppler indices than by means of the middle cerebral artery pulsatility index (52% versus 20%, P = 0.002). In conclusion, two of the three indices increased during gestation. All the fetal cerebral 3D vascular indices are increased in fetuses with FGR. In these fetuses, there were more cases suggesting hemodynamic redistribution than expected by conventional Doppler studies.
Postischemic IGF-1 Gene Transfer Promotes Neurovascular Regeneration after Experimental Stroke
Authors: Zhu Wei , Fan Yongfeng , Hao Qi , Shen Fanxia , Hashimoto Tomoki , Yang Guo-Yuan , Gasmi Mehdi , Bartus Raymond T , Young William L , Chen Yongmei
Published: June 2009

Promoting neural regeneration after cerebral infarction has emerged as a potential approach for the treatment of stroke. Insulin-like growth factor 1 (IGF-1) possesses both neurotrophic and angiogenic properties. The aim of this study was to determine whether postischemic gene transfer of IGF-1 enhances neurovascular regeneration in a mouse model of permanent focal cerebral ischemia. Long-term cerebral IGF-1 overexpression was achieved with adeno-associated viral vector (AAV) by stereotaxic injection at 24 h after a stroke. Adeno-associated viral vector-green fluorescent protein (GFP) or saline was injected as a control. The success of postischemic gene transduction was confirmed by a strong GFP signal and by increased IGF-1 protein expression in the peri-infarct region. Postischemic gene transfer of IGF-1 significantly enhanced vascular density at 8 weeks after a stroke in the peri-infarct and injection needle tract area compared with AAV-GFP or saline treatment, as shown by immunohistochemical staining with the vascular marker lectin. Furthermore, increased vascular density was associated with improved local vascular perfusion. Immunohistochemical staining with the neuronal progenitor marker, DCX (doublecortin), and the cell proliferation marker, BrdU (5-bromo-2-deoxyuridine-5-monophosphate), indicated that AAV-IGF-1 treatment potently increased neurogenesis compared with AAV-GFP injection. These data show that postischemic treatment of IGF-1 effectively promoted neural and vascular regeneration in the chronic stage of cerebral infarction.
Research on three dimensional machining effects using atomic force microscope
Authors: Mao Yao-Ting , Kuo Kai-Chen , Tseng Ching-En , Huang Jian-Yin , Lai Yi-Chih , Yen Jia-Yush , Lee Chih-Kung , Chuang Wei-Li
Published: June 2009

This research studies the use of scanning probe microscope as the tool to manufacture three dimensional nanoscale objects. We modified a commercial atomic force microscope (AFM) and replaced the original probe control system with a personal computer (PC) based controller. The modified system used the scanning probe in the AFM for the cutting tool and used the PC controller to control work piece. With the new controller, one could implement multiaxes motion control to perform trajectory planning and to test various cutting strategies. The experiments discovered that the debris can coalesce with the sample material and cause tremendous problem in the nanomachining process. This research thus proposed to make use of this material and developed a piling algorithm to not only cut but also pile up the debris in a favorable way for steric shaping. The experimental results showed that the proposed cutting and shaping algorithm can produce nano-objects as high as a few hundred nanometers. The probe tip typically wears down to around 500 μm diameter after the machining process, putting a limit on the machining resolution. The vertical resolution can achieve less than 10 nm without controlled environment.
Time propagation of the Kadanoff–Baym equations for inhomogeneous systems
Authors: Stan Adrian , Dahlen Nils Erik , van Leeuwen Robert
Published: June 2009

We have developed a time-propagation scheme for the Kadanoff–Baym equations for general inhomogeneous systems. These equations describe the time evolution of the nonequilibrium Green function for interacting many-body systems in the presence of time-dependent external fields. The external fields are treated nonperturbatively whereas the many-body interactions are incorporated perturbatively using Φ-derivable self-energy approximations that guarantee the satisfaction of the macroscopic conservation laws of the system. These approximations are discussed in detail for the time-dependent Hartree–Fock, the second Born, and the GW approximation.
Weak link behavior of Be doped (Cu0.5K0.25Tl0.25)Ba2(Ca3−xBex)Cu4O12−δ superconductors
Authors: Khan Nawazish A. , Manzoor Syed Asad
Published: June 2009

A systematic study of the weak link behavior for Be doped (Cu0.5K0.25Tl0.25)Ba2(Ca3−xBex)Cu4O12−δ (x=0,0.5,0.75,1.0,1.25,1.5) superconductors is carried out. Calcium atom in the unit cell of aforementioned compound separates the conducting CuO2 planes and the doping of smaller sized beryllium at those sites would enhance the interplane coupling. The critical temperature and magnitude of diamagnetism have been found to increase with increased Be doping concentrations up to x=1.25. For Be doped samples, the Tc(R=0) and magnitude of diamagnetism is enhanced further with the postannealing in oxygen atmosphere. The increased magnitude of diamagnetism after postannealing in oxygen atmosphere is most likely accomplished by the optimization of carriers in the conducting CuO2 planes. It is observed in the infield magnetic measurements that peak temperature (Tp) in the Be doped samples postannealed in oxygen atmosphere survives to much higher external magnetic fields as compared to Be free samples. These observations suggested that it is most likely that partial diffusion of smaller size Be at the termination ends of the grains improves the intergrain weak links and enhances their superconducting properties. After postannealing in oxygen the intergranular connectivity is improved further with the diffusion of oxygen at the grain boundaries. The critical current densities of the samples calculated by using Bean’s critical state model have been found to increase with the enhanced Be doping in oxygen postannealed samples. The Jc values so obtained are linearly fitted to the power law behavior of the type (1−T/Tc)n for various values of n. Both the as-prepared and oxygen postannealed samples gave a best fit for n=1 appropriate for the superconductor insulator superconductor junction. This nature of material is most likely due to oxide formation at the grain boundaries due to oxygen diffusion, which possibly provide large surface areas to the shielding current flows and enhance the Jc of the final compound.
rf testbed for thermoacoustic tomography
Authors: Fallon D. , Yan L. , Hanson G. W. , Patch S. K.
Published: June 2009

Thermoacoustic signal excitation is a function of intrinsic tissue properties and illuminating electric field. De-ionized (DI) water is a preferred acoustic coupling medium for thermoacoustics because acoustic and electromagnetic waves propagate in DI water with very little loss. We have designed a water-filled testbed propagating a controlled electric field with respect to pulse shape, power, and polarization. Directional coupler line sections permit measurement of incident, reflected, and transmitted powers. Both S-parameters and Ey measurement show that the electric-field distribution is relatively uniform in testbed. Comparing baseline power measurements to those taken with a test object in place yields power loss in the object, which should correlate to thermoacoustic signal strength. Moreover, power loss—and therefore thermoacoustic computerized tomography signal strength—is sensitive to the orientation of the object to the polarization of the electric field. This testbed will enable quantitative characterization of the thermoacoustic contrast mechanism in ex vivo tissue specimens.
Ion yields and erosion rates for Si1−xGex(≤x≤1) ultralow energy O2+ secondary ion mass spectrometry in the energy range of 0.25–1 keV
Authors: Morris R. J. H. , Dowsett M. G.
Published: June 2009

We report the SIMS parameters required for the quantitative analysis of Si1−xGex across the range of 0≤x≤1 when using low energy O2+ primary ions at normal incidence. These include the silicon and germanium secondary ion yield [i.e., the measured ion signal (ions/s)] and erosion rate [i.e., the speed at which the material sputters (nm/min)] as a function of x. We show that the ratio Rx of erosion rates, Si1−xGex/Si, at a given x is almost independent of beam energy, implying that the properties of the altered layer are dominated by the interaction of oxygen with silicon. Rx shows an exponential dependence on x. Unsurprisingly, the silicon and germanium secondary ion yields are found to depart somewhat from proportionality to (1−x) and x, respectively, although an approximate linear relationship could be used for quantification across around 30% of the range of x (i.e., a reference material containing Ge fraction x would give reasonably accurate quantification across the range of ±0.15x). Direct comparison of the useful (ion) yields [i.e., the ratio of ion yield to the total number of atoms sputtered for a particular species (ions/atom)] and the sputter yields [i.e., the total number of atoms sputtered per incident primary ion (atoms/ions)] reveals a moderate matrix effect where the former decrease monotonically with increasing x except at the lowest beam energy investigated (250 eV). Here, the useful yield of Ge is found to be invariant with x. At 250 eV, the germanium ion and sputter yields are proportional to x for all x.
Experimental investigation of the large-scale velocity statistics in homogeneous turbulent shear flow
Authors: Isaza Juan C. , Warhaft Zellman , Collins Lance R. ,   International Collaboration for Turbulence Research
Published: June 2009

Motivated by the numerical results of Isaza and Collins [“On the asymptotic behaviour of large-scale turbulence in homogeneous shear flow,” J. Fluid Mech. (in press)], the sensitivity of the self-similar behavior of the large-scale velocity statistics in an homogeneous turbulent shear flow to the initial value of the shear parameter and Reynolds number is investigated in a wind tunnel. Using an active grid, the initial value of Reynolds number based on the Taylor microscale is varied over the range 100≤Rλ≤250. The shear is generated using screens of different solidities followed by a series of straightening channels [S. Garg and Z. Warhaft, Phys. Fluids 10, 662 (1998)], allowing us to vary the initial value of the shear parameter over the modest range 6≤S0*≤12. We find that the longtime behavior of the shear parameter depends on its initial value over the nondimensional time interval 5≤St≤25, but is less sensitive to the initial value of the Reynolds number. The ratio of the turbulent kinetic energy production over dissipation rate appears to show a similar dependence on the initial value of the shear parameter, but there is more significant scatter in the data. We find that the turbulent kinetic energy grows with downstream distance, in agreement with previous work, and that its growth rate too is a stronger function of the initial shear parameter than the initial Reynolds number. The experimental results for all of the large-scale velocity statistics are consistent with the earlier direct numerical simulation study.
Rational design of high-responsivity detectors of terahertz radiation based on distributed self-mixing in silicon field-effect transistors
Authors: Lisauskas Alvydas , Pfeiffer Ullrich , Öjefors Erik , Bolìvar Peter Haring , Glaab Diana , Roskos Hartmut G.
Published: June 2009

In search of novel detectors of electromagnetic radiation at terahertz frequencies, field-effect transistors (FETs) have recently gained much attention. The current literature studies them with respect to the excitation of plasma waves in the two-dimensional channel. Circuit aspects have been taken into account only to a limited degree. In this paper, we focus on embedding silicon FETs in a proper circuitry to optimize their responsivity to terahertz radiation. This includes impedance-matched antenna coupling and amplification of the rectified signal. Special attention is given to the investigation of high-frequency short-circuiting of the gate and drain contacts by a capacitive shunt, a common approach of high-frequency electronics to induce resistive mixing in transistors. We theoretically study the effect of shunting in the framework of the Dyakonov–Shur plasma-wave theory, with the following key results. In the quasistatic limit, the capacitive shunt induces the longitudinal high-frequency field needed in the FET’s channel for resistive mixing. In the non-quasi-static case, the shunt’s role is taken over by plasma waves. Rectification can then be described as distributed self-mixing in the transistor’s channel. Based on such considerations as well as other circuit-related aspects, we arrive at a rational design for FET-based detectors of terahertz radiation, and implement the first monolithically integrated 0.65 THz focal-plane array including antennas and amplifiers on a single silicon die. The measured performance data compare well with the theoretical predictions.
Characterization of unswept and swept quartz crystals for space applications
Authors: Lefèvre J. , Devautour-Vinot S. , Cambon O. , Boy J.-J. , Guibert P. , Chapoulie R. , Inguimbert C. , Picchedda D. , Largeteau A. , Demazeau G. , Cibiel G.
Published: June 2009

Unswept and vacuum-swept synthetic quartz crystals were investigated in order to determine the mechanisms responsible for the radiation sensitivity of this material. Results were obtained by means of infrared (IR) spectroscopy, dielectric relaxation spectroscopy (DRS), and thermoluminescence (TL). First, the effect of vacuum sweeping was clearly demonstrated in IR absorption by a significant decrease in the amount of hydroxyl ions and in DRS by the disappearance of the dielectric loss peak arising from the relaxation of alkali ions. Second, it was shown that swept quartz is less sensitive to irradiation than the unswept crystal. A sharp decrease in the TL sensitivity of the electrolyzed material was observed in the energy range corresponding to the recombination of alkaline-electronic defects. DRS results indicated that the dielectric signal is shifted toward a lower energy range for both types of crystals, suggesting that the irradiation greatly facilitates the relaxation of alkaline species by creating low energy hosting sites. However, this shift is drastically less pronounced in the swept quartz because relaxing species are more stable in this material. Third, a correlation was established in TL between trapped charge carriers at point defects in quartz and the frequency variation in quartz oscillators, which is a very promising result for space applications.
Effects of dimensionality on the ballistic phonon transport and thermal conductance in nanoscale structures
Authors: Zhou Ling-Ping , Wang Ming-Pu , Zhu Jia-Jun , Peng Xiao-Fang , Chen Ke-Qiu
Published: June 2009

Using the scattering-matrix method, we investigate ballistic phonon transport and thermal conductance at low temperatures in a two-dimensional and a three-dimensional nanoscale structures modulated with a finite Cu/W superlattice. A comparative analysis for two-dimensional and three-dimensional models is made. The results show that the thermal conductance in three-dimensional model is larger than that in two-dimensional model for same structural parameters and temperature. In characteristics, however, the thermal conductance displays similar behaviors in both two-dimensional and three-dimensional models. Moreover, some interesting physical phenomena such as stop-frequency gap, resonant transmission, and universal quantized thermal conductance are observed in the structures. A brief analysis of these results is given.
Arbitrary amplitude ion-acoustic solitary excitations in the presence of excess superthermal electrons
Authors: Saini N. S. , Kourakis I. , Hellberg M. A.
Published: June 2009

Velocity distribution functions with an excess of superthermal particles are commonly observed in space plasmas, and are effectively modeled by a kappa distribution. They are also found in some laboratory experiments. In this paper we obtain existence conditions for and some characteristics of ion-acoustic solitary waves in a plasma composed of cold ions and κ-distributed electrons, where κ>3/2 represents the spectral index. As is the case for the usual Maxwell–Boltzmann electrons, only positive potential solitons are found, and, as expected, in the limit of large κ one recovers the usual range of possible soliton Mach numbers, viz., 1<M<1.58. For lower values of κ, modeling the presence of a greater superthermal component, the range of accessible Mach numbers is reduced. It is found that the amplitude of the largest possible solitons that may be generated in a given plasma (corresponding to the highest allowed Mach number for the given plasma composition) falls off with decreasing κ, i.e., an increasing superthermal component. On the other hand, at fixed Mach number, both soliton amplitude and profile steepness increase as κ is decreased. These changes are seen to be important particularly for κ<4, i.e., when the electrons have a “hard” spectrum.
Structures generated in a temperature filament due to drift-wave convection
Authors: Shi M. , Pace D. C. , Morales G. J. , Maggs J. E. , Carter T. A.
Published: June 2009

A simplified numerical study is made of the structures that are formed in a magnetized temperature filament due to oscillatory convection from large amplitude drift waves. This study is motivated by a recent experiment [D. C. Pace, M. Shi, J. E. Maggs et al., Phys. Plasmas 15, 122304 (2008)] in which Lorentzian-shaped temporal pulses are observed. These pulses produce a broadband, exponential frequency power spectrum. The model consists of an electron heat transport equation in which plasma convection arising from pressure-gradient driven drift-waves is included. It is found that above a critical wave amplitude, spatially complex structures are formed, which give rise to temporal pulses having positive and negative polarities at different radial positions. The temporal shape of the pulses can be fit by a Lorentzian function. The associated spatial structures exhibit temporally oscillatory heat plumes (positive polarity) and cold channels (negative polarity). The idealized effect of a static flow on these structures is explored. Depending on the flow direction (relative to the azimuthal propagation of the drift waves), the temporal Lorentzian pulses can be suppressed.
Exciton dissociation and photovoltaic effect in germanium nanocrystals and poly(3-hexylthiophene) composites
Authors: Sun Baoquan , Zou Guifu , Shen Xiaojuan , Zhang Xiaohong
Published: June 2009

Exciton dissociation and carrier transport in poly(3-hexylthiophene) (P3HT)/germanium (Ge) nanocrystals composites were investigated by steady-state and time-resolved photoluminescence (PL) as well as photovoltaic (PV) effect. Quenching of the PL quantum yield η and shortening of the PL lifetime τ in the composites were observed, which were ascribed to rapid exciton dissociate at the interface. PV devices were fabricated based on Ge/P3HT composites sandwiched between indium tin oxide and aluminum. The external quantum efficiency spectrum displayed wide photoresponse range, covering both nanocrystals absorption range and P3HT one. Large open circuit voltage up to 0.45 V and obvious short-circuit current were demonstrated in hybrid Ge nanocrystals/P3HT PV device.
A Chemoenzymatic Route to Conjugatable β(1→3)-Glucan Oligosaccharides
Authors: Montel Emilie , Hrmova Maria , Fincher Geoffrey B. , Driguez Hugues , Cottaz Sylvain
Published: June 2009

3II-O-Allyl-α-laminaribiosyl fluoride was prepared as a key synthon for the enzymatic synthesis of β(1→3)-glucan oligosaccharides, catalyzed by a mutated β(1→3)-glucanase (E231G) from barley (Hordeum vulgare L.). A strategy was developed for enzymatic elongation of the β(1→3)-glucan chain from the reducing end, using a single glucoside acceptor. When β-glucoside phenyl disulfide was used as the acceptor, this methodology generated laminari-oligosaccharides conjugatable at both their reducing and non-reducing ends.
The Chitopentaose Complex of a Mutant Hen Egg-White Lysozyme Displays No Distortion of the –1 Sugar Away from a 4C1 Chair Conformation
Authors: Davies Gideon J. , Withers Stephen G. , Vocadlo David J.
Published: June 2009

Glycosidase inhibitors frequently reflect either the charge or the ‘flattened’ shape of the oxocarbenium-ion like transition state. Much of the impetus for such inhibitory strategies derives from historical studies on ligand binding to hen egg white lysozyme (HEWL); not least those suggesting that product complexes of the enzyme showed distortion of the pyranosides in the –1 subsite. Ironically, while distortion is undoubtedly a defining feature of glycosidases, product complexes themselves are rarely distorted. Here we show that the chitopentaose product complex of a mutant E35Q HEWL, solved at 1.8 Å resolution, is bound with all sugars in 4C1 conformation.
Phylogeny and classification of Eucalyptus subgenus Eudesmia (Myrtaceae) based on nuclear ribosomal DNA, chloroplast DNA and morphology
Authors: Gibbs Adele K. , Udovicic Frank , Drinnan Andrew N. , Ladiges Pauline Y.
Published: June 2009

Phylogenetic analysis of Eucalyptus subgenus Eudesmia is presented on the basis of the following three datasets: sequences of the internal transcribed spacer (ITS) and the external transcribed spacer (ETS) regions from nuclear rDNA, sequences of the psbA–trnH intergenic spacer region from chloroplast DNA, and morphological characters, including stamen bundling, operculum development, seeds and trichomes. Studies of floral development were essential for understanding the morphology of mature flowers and interpretation of synapomorphy and homoplasy. A summary phylogeny was constructed from a maximum parsimony analysis of those nodes coded as characters that had support in the molecular trees together with morphological characters. A revised infra-subgeneric classification is presented on the basis of the summary phylogeny, and compared with classifications of Hill and Johnson (1998) and Brooker (2000). Differences relate to relationships between clades and taxonomic rank (sections, series and subseries) and valid names of Brooker (2000) are conserved where possible. One main clade of 14 species (section Limbatae), many of mallee growth form, was found in all analyses; this clade is distributed in the South-West of Western Australia and adjacent Interzone and desert areas. A second main clade (section Complanatae) occurs in the northern and eastern tropical and subtropical regions of Australia, including Kimberley, Arnhem, Queensland and New South Wales. This section includes E. tetrodonta, previously treated as an isolated taxon in a monotypic section; however, this species is related to E. baileyana, E. similis, E. lirata and series Miniatae. The hypothesised phylogeny provides a framework for further analyses of biogeography and ecology, including functional traits.