bluuebunny/crossref_metadata_2025 huggingface dataset:
Facial nerve outcomes in functional vestibular schwannoma surgery: less than total tumour excision significantly improves results
Authors: Martin T P C , Fox H , Ho E-C , Holder R , Walsh R , Irving R M
Published: December 2011

Objectives:

To determine the implications of a functional approach to vestibular schwannoma surgery, with facial nerve function prioritised higher than total tumour excision.

Study design:

A case–control study in a tertiary referral neurotology clinic.

Patients:

A ‘functional’ surgical group treated after April 2007 (n = 44, mean cerebellopontine angle dimension 27 mm), and an ‘excisional’ surgical group matched for tumour size, treated from 1997 to April 2007 (n = 115).

Intervention:

Change to more functional surgical approach.

Main outcomes measured:

Primary outcome: facial nerve status. Secondary outcome: tumour recurrence in less-than-total tumour excision.

Results:

Facial nerve preservation: 77 per cent House–Brackmann grade I–II in functional group at 12 months, versus 57 per cent grade I–II in excisional group (p = 0.027). Tumour recurrence: 1 per cent in total excision group, 2 per cent in near-total group and 40 per cent in sub-total group.

Conclusion:

A functional approach to vestibular schwannoma surgery improves facial nerve preservation outcomes and reduces the requirement for facial nerve rehabilitative interventions. Tumour recurrence rates are low in near-totally excised lesions but significant if only sub-total excision is achieved.
Predicting persistent alcohol problems: a prospective analysis from the Great Smoky Mountain Study
Authors: Copeland W. E. , Angold A. , Shanahan L. , Dreyfuss J. , Dlamini I. , Costello E. J.
Published: December 2011

Background

Rates of alcohol disorders peak in late adolescence and decrease substantially into the mid-20s. Our aim was to identify risk factors that predict alcohol problems that persist into the mid-20s.

Method

Data are from the prospective, population-based Great Smoky Mountains Study (GSMS; n=1420), which followed children through late adolescence and into young adulthood. Alcohol persisters were defined as subjects with an alcohol disorder (abuse or dependence) in late adolescence (ages 19 and 21 years) that continued to meet criteria for an alcohol disorder at the mid-20s assessment.

Results

The 3-month prevalence of having an alcohol disorder (abuse or dependence) decreased markedly from late adolescence into the mid-20s. A third of late adolescents with an alcohol disorder continued to meet criteria for an alcohol disorder in young adulthood (37 of 144 who met criteria in late adolescence). Risk factors for persister status included multiple alcohol abuse criteria during late adolescence but no alcohol dependence criteria. Risk factors for persister status also included associated features of alcohol dependence such as craving alcohol and drinking to unconsciousness. Persister status was also associated with depression, cannabis dependence and illicit substance use, but not with other psychiatric disorders. More than 90% of late adolescents with three or more of the risk factors identified met criteria for a young adult alcohol disorder.

Conclusions

Symptoms of alcohol abuse, not dependence, best predict long-term persistence of alcohol problems. The set of risk factors identified may be a useful screen for selective and indicated prevention efforts.
Prevalence of post-traumatic stress disorder among adolescents after the Wenchuan earthquake in China
Authors: Zhang Z. , Ran M.-S. , Li Y.-H. , Ou G.-J. , Gong R.-R. , Li R.-H. , Fan M. , Jiang Z. , Fang D.-Z.
Published: December 2011

Background

The Wenchuan earthquake was a catastrophic earthquake in China. The aim of this study is to explore longitudinally the rates of post-traumatic stress disorder (PTSD) and depression in adolescents after the Wenchuan earthquake, and to identify independent predictors of PTSD.

Method

PTSD and depression symptoms among adolescents at 6, 12 and 18 months after the Wenchuan earthquake were investigated using the PTSD Checklist Civilian Version and the Beck Depression Inventory (BDI). Subjects in this study included 548 high school student survivors in a local boarding high school.

Results

The rates of PTSD symptoms were 9.7%, 1.3% and 1.6% at the 6-, 12- and 18-month follow-ups, respectively. BDI scores were found to be the best predictor of severity of PTSD at 6, 12 and 18 months. Gender was another variable contributing significantly to PTSD at 6 and 12 months after the earthquake. In the 12-month follow-up, home damage was found to be a predictor of severity of PTSD symptoms. Being a child with siblings was found to be a predictor of severity of PTSD symptoms at 12 and 18 months after the earthquake.

Conclusions

PTSD symptoms changed gradually at various stages after the earthquake. Depression symptoms were predictive of PTSD symptoms in the 18-month follow-up study. Other predictors of PTSD symptoms included female gender and being a child with siblings. The results of this study may be helpful for further mental health interventions for adolescents after earthquakes.
Approximate groups and doubling metrics
Authors: SANDERS TOM
Published: December 2011

We develop a version of Freĭman's theorem for a class of non-abelian groups, which includes finite nilpotent, supersolvable and solvable A-groups. To do this we have to replace the small doubling hypothesis with a stronger relative polynomial growth hypothesis akin to that in Gromov's theorem (although with an effective range), and the structures we find are balls in (left and right) translation invariant pseudo-metrics with certain well behaved growth estimates.

Our work complements three other recent approaches to developing non-abelian versions of Freĭman's theorem by Breuillard and Green, Fisher, Katz and Peng, and Tao.
Zeroes of the spectral density of the periodic Schrödinger operator with Wigner–von Neumann potential
Authors: NABOKO SERGUEI , SIMONOV SERGEY
Published: December 2011

We consider the Schrödinger operator α on the half-line with a periodic background potential and the Wigner–von Neumann potential of Coulomb type: csin(2ωx + δ)/(x + 1). It is known that the continuous spectrum of the operator α has the same band-gap structure as the free periodic operator, whereas in each band of the absolutely continuous spectrum there exist two points (so-called critical or resonance) where the operator α has a subordinate solution, which can be either an eigenvalue or a “half-bound” state. The phenomenon of an embedded eigenvalue is unstable under the change of the boundary condition as well as under the local change of the potential, in other words, it is not generic. We prove that in the general case the spectral density of the operator α has power-like zeroes at critical points (i.e., the absolutely continuous spectrum has pseudogaps). This phenomenon is stable in the above-mentioned sense.
Whoopie Pies, Supersized Fries
Authors: FLECK LEONARD M.
Published: December 2011

The annual cost of healthcare in the United States reached $2.5 trillion in 2009 (about 17.6% of GDP) with projections to 2019 of about $4.5 trillion (about 20% of likely GDP).
In Defense of Broad Consent
Authors: HELGESSON GERT
Published: December 2011

Proper procedures for informed consent are widely recognized as an ethical requirement for biomedical research involving human beings, in particular as a means to respect the autonomy and personal integrity of potential and actual research participants.
Research Priorities and the Future of Pregnancy
Authors: MURPHY TIMOTHY F.
Published: December 2011

The term “ectogenesis” has been around for about a century now, and it is generally understood as the development of embryos and fetuses outside a uterus. In this sense, all in vitro fertilization (IVF) is ectogenesis, but in vitro development can only proceed to a certain point, at which time human embryos are then either implanted in the attempt to achieve a pregnancy, frozen for that use in the future, used in research, or discarded.
From Pioneers to Professionals
Authors: PARNAMI SONALI S. , LIN KATHERINE Y. , FESSLER KATHRYN BONDY , BLOM ERICA , SULLIVAN MATTHEW , DE VRIES RAYMOND G.
Published: December 2011

Bioethics has made remarkable progress as a scholarly and applied field. A mere fledgling in the 1960s, it is now firmly established in hospitals, medical schools, and government agencies and boasts a number of professional associations and a handsome collection of journals.
A Woman (and Man) without a Country
Authors: BOSSLET GABRIEL
Published: December 2011

Lying in bed, the shriveled 86-year-old Australian woman appeared almost bionic. Congestive heart failure had rendered Mrs. A unable to breathe without a ventilator, and her failing kidneys kept her tethered to a dialysis machine 24 hours per day.
New concepts: development of a survivorship programme for patients with a functionally univentricular heart
Authors: Goldberg David J. , Dodds Kathryn , Rychik Jack
Published: December 2011

Children with functionally univentricular hearts are now surviving into their third and fourth decades of life. Although survival alone is a remarkable achievement, a lot must still be done to improve the quality and duration of life after the Fontan operation. Challenges that may be faced by these patients include the impact of the Fontan operation on the liver and the density of bone, protein-losing enteropathy, and plastic bronchitis. Paediatric cardiologists are familiar with the haemodynamic issues inherent in Fontan physiology; however, training in cardiology is often not sufficient to give us a complete understanding of the pathophysiology of the complications or of the options for treatment. Collaboration with other subspecialists including gastroenterologists, endocrinologists, and pulmonologists is essential in order to provide the rigorous and nuanced care that our patients need and deserve. A clinic in which a patient can see multiple subspecialists, and in which the subspecialists, as a group, can discuss each patient, can provide a unique and valuable service for patients with a functionally univentricular heart.
Intermediate-term outcomes after paediatric cardiac extracorporeal membrane oxygenation – what is known (and unknown)
Authors: Costello John M. , Cooper David S. , Jacobs Jeffrey P. , Chai Paul J. , Kirsch Roxanne , Rosenthal Tami , Dalton Heidi J. , Graziano Joseph N. , Quintessenza James A.
Published: December 2011

The use of extracorporeal membrane oxygenation in infants and children with cardiac disease who develop refractory cardiogenic shock, cyanosis, or cardiac arrest is increasing. Early mortality in children with cardiac disease who require extracorporeal membrane oxygenation remains an important issue, as only 40% of cannulated patients survive to discharge from the hospital. However, it is encouraging that 90% children who are discharged alive from the hospital after extracorporeal membrane oxygenation are still alive at intermediate-term follow-up. Surviving patients are at risk for long-term dysfunction of multiple organ systems related to their underlying cardiac disease, non-cardiac comorbidities, treatment-related complications, and exposure to extracorporeal membrane oxygenation. Among the most important acute complications related to support with extracorporeal membrane oxygenation is injury to the central nervous system, which may contribute to adverse neurodevelopmental outcomes. All of these factors, in turn, influence quality of life. Many survivors remain medically complex related to their underlying cardiac disease, comorbidities, and sequelae of complications acquired over their lifetime. Neurological morbidity clearly plays an important role in approximately one-third of survivors, with significant deficits in approximately 10%. The limited data about quality of life data that are available for survivors of cardiac extracorporeal membrane oxygenation suggests that approximately 15–30% of survivors have at least moderately decreased quality of life. Overall, published data support the ongoing use of support with extracorporeal membrane oxygenation in children with acute cardiac failure, most of whom would die without it. However, programmatic efforts to improve the selection of patients and the preservation of the function of end organs during extracorporeal membrane oxygenation are clearly needed in order to improve long-term outcomes.
Investment regionalism in Asia: new directions in law and policy?
Authors: PEKKANEN SAADIA
Published: December 2011

Although Asian regionalism has commanded much attention from academics and policymakers, it has largely been restricted to the trade and financial realms. This paper focuses specifically on the scope and limits of ‘investment regionalism’ involving Asia. A combination of regional foreign direct investment (FDI) stakes and international socialization patterns has led Asian actors to mark investments as a key issue in their regionalism strategy overall. As elsewhere, they too have moved toward a mode of governance favoring the formal legalization of investments in terms of the precision, obligation, and delegation of rules. Already the endeavors of both the middle and dominant economies in the region have shifted from just concluding Bilateral Investment Treaties (BITs) and investment-related chapters in Free Trade Agreements (FTAs) to designing region-wide investment agreements and initiatives by-and-for Asian countries. Although the legal effectiveness of this rule-making change will play out in the long run in and across Asian societies, the more immediate policy implication relates to its potential impact on the evolution of Asian regionalism as a whole.
Exceptional divisors that are not uniruled belong to the image of the Nash map
Authors: Lejeune-Jalabert Monique , Reguera Ana J.
Published: December 2011

We prove that, ifXis a variety over an uncountable algebraically closed fieldkof characteristic zero, then any irreducible exceptional divisorEon a resolution of singularities ofXwhich is not uniruled, belongs to the image of the Nash map, i.e. corresponds to an irreducible component of the space of arcs$X_\infty^{\mathrm{Sing}}$onXcentred in SingX. This reduces the Nash problem of arcs to understanding which uniruled essential divisors are in the image of the Nash map, more generally, how to determine the uniruled essential divisors from the space of arcs.
Reasons why armed groups choose to respect international humanitarian law or not
Authors: Bangerter Olivier
Published: December 2011

The decision to respect the law – or not – is far from automatic, regardless of whether it is taken by an armed group or a state. Respect for international humanitarian law (IHL) can only be encouraged, and hence improved, if the reasons used by armed groups to justify respect or lack of it are understood and if the arguments in favour of respect take those reasons into account. Among the reasons for respecting the law, two considerations weigh particularly heavily for armed groups: their self-image and the military advantage. Among the reasons for non-respect, three are uppermost: the group's objective, the military advantage, and what IHL represents according to the group.
Age of onset of mental disorders and use of mental health services: needs, opportunities and obstacles
Authors: de Girolamo G. , Dagani J. , Purcell R. , Cocchi A. , McGorry P. D.
Published: December 2011

Purpose of review.

In this review, we provide an update of recent studies on the age of onset (AOO) of the major mental disorders, with a special focus on the availability and use of services providing prevention and early intervention.

Recent findings.

The studies reviewed here confirm previous reports on the AOO of the major mental disorders. Although the behaviour disorders and specific anxiety disorders emerge during childhood, most of the high-prevalence disorders (mood, anxiety and substance use) emerge during adolescence and early adulthood, as do the psychotic disorders. Early AOO has been shown to be associated with a longer duration of untreated illness, and poorer clinical and functional outcomes.

Although the onset of most mental disorders usually occurs during the first three decades of life, effective treatment is typically not initiated until a number of years later. There is increasing evidence that intervention during the early stages of disorder may help reduce the severity and/or the persistence of the initial or primary disorder, and prevent secondary disorders. However, additional research is needed on effective interventions in early-stage cases, as well as on the long-term effects of early intervention, and for an appropriate service design for those with emerging mental disorders. This will mean not only the strengthening and re-engineering of existing systems, but is also crucial the construction of new streams of care for young people in transition to adulthood.
Die stationäre Suchtkrankenhilfe – Daten aus der medizinischen Rehabilitation im Überblick
Authors: Missel Peter , Koch Andreas
Published: December 2011

Zielsetzung: Die Daten der Deutschen Suchthilfestatistik (DSHS) werden jährlich bundesweit von ambulanten und stationären Einrichtungen der Suchtkrankenhilfe erhoben. Die Einrichtungen orientieren sich dabei an den einheitlichen Vorgaben des Deutschen Kerndatensatzes (KDS), der von der DHS unter Beteiligung aller maßgeblichen Suchtverbände entwickelt wurde. Die vorliegende Untersuchung bezieht sich dabei ausschließlich auf die Daten aus 157 teilstationären (ganztägig ambulanten), stationären Rehabilitations- sowie Adaptionseinrichtungen. Methode: Daten aus den stationären Entwöhnungsbehandlungen 2009 werden hinsichtlich der Art der teilnehmenden Einrichtungen und bzgl. der behandelten Patienten u. a. hinsichtlich soziodemografischer Daten, Diagnosen und Komorbiditäten und Daten zum Behandlungsverlauf analysiert. Ergebnisse: Die Nationale Suchthilfestatistik zeigt eine Teilnehmerquote bzgl. der in Deutschland existierenden Rehabilitationseinrichtungen von 42,5 %, bzgl. der in Leistungsträgerschaft der Deutschen Rentenversicherung durchgeführten Behandlungen von 59,5 %. Routinemäßige Basisdokumentation und Katamnestik sind inzwischen Standard der teilnehmenden Einrichtungen. Die Zertifizierungsquote liegt noch deutlich unter der bis Herbst 2012 erforderlichen Zertifizierungspflicht. Bezogen auf die durchgeführten Behandlungen sind Behandlungen mit der Hauptdiagnose Alkohol die weitaus größte Störungsgruppe. Die Klientel weist eine hohe Komorbidität auf. Mehr als die Hälfte der Patienten war bei Behandlungsbeginn und Behandlungsende arbeitslos. Die Behandlungsergebnisse zeigen hohe Haltequoten, diese sind für Patienten mit den Hauptdiagnosen pathologisches Glücksspielen und Alkohol am höchsten. Schlussfolgerungen: Die Ergebnisse sprechen für eine hohe Behandlungsqualität bei komorbider Klientel in den stationären Rehabilitationseinrichtungen in Deutschland. Insbesondere bei der Entwicklung spezifischer Zielgruppenkonzepte für Patienten mit komorbiden Störungen sowie hinsichtlich der medizinisch-beruflich-orientierten Rehabilitation besteht weiterer Entwicklungsbedarf.
Recent thermohaline trends of the Atlantic waters inflowing to the Mediterranean Sea
Authors: Soto‐Navarro Javier , Criado‐Aldeanueva Francisco , Sánchez‐Garrido Jose Carlos , García‐Lafuente Jesús
Published: December 2011

A total of 5077 Argo float profiles in the period 01/2002‐05/2010 have been used to analyze salinity and temperature trends in the Atlantic waters adjacent to the Strait of Gibraltar in order to identify the source of recent changes observed in the inflow to the Mediterranean Sea. Positive salinity trends of 0.038 ± 0.009 year−1 and 0.013 ± 0.003 year−1 have been found for the Surface Atlantic Water and the Eastern North Atlantic Central Water, respectively. For temperature, no significant trend is observed in the surface layer while positive trend of 0.05 ± 0.02 °C/year is obtained for the thermocline waters. The Mediterranean Water layer does not show any significant trend for the entire period, but a switch from positive to negative trends is observed in year 2006. In contrast to previous findings, these thermohaline variations are driven by intrinsic water masses changes, instead of isopycnal vertical displacements, probably related to an enhancement of the net freshwater losses in the area.
Is a global warming signature emerging in the tropical Pacific?
Authors: Ashok K. , Sabin T. P. , Swapna P. , Murtugudde R. G.
Published: December 2011

The tropical pacific experienced a hitherto‐unseen anomalous basinwide warming from May 2009 through April 2010 with the maximum warming to the east of the dateline, but for a weak anomalous cooling west of 140°E after early boreal fall. Our observed analysis and model experiments isolate the potential teleconnections from TP during the summer of 2009. Further, we show through an empirical orthogonal function analysis of the tropical Pacific SSTA that the anomalous conditions in TP during this period could have manifested as a canonical El Niño, but for a slowly intensifying background west–east gradient. This zonal SST gradient is subject to an increasing trend associated with global warming. A possible implication is that any further increase in global warming may result in more basinwide warm events in place of canonical El Niños, along with the occurrence of more intense La Niñas and El Niño Modokis.
Irregularity excitation associated with charged dust cloud boundary layers
Authors: Mahmoudian A. , Scales W. A.
Published: December 2011

Irregularity generation associated with dust cloud expansion through a background plasma along a magnetic field is investigated. Because of the dust charging process, a boundary layer is produced, separating the dusty plasma generated and the background plasma. It is observed that under appropriate conditions, localized plasma irregularities may be generated in this boundary layer. Theoretical and computational models are used to study the evolution of relevant plasma instabilities thought to play a dominant role in irregularity production. An electron flow develops along the boundary layer of the dust cloud, and plasma irregularities are generated in response to this flow. Several aspects of the cloud's structure (thickness of the boundary layer, average particle size and density, collisional processes, and cloud expansion speed) and the ambient plasma are varied to determine the effect of these quantities on the resulting irregularities. The relevance of these results to past experimental observations in space and the laboratory for applications to the expansion of naturally or artificially created dust clouds is discussed.
A survey of the polar cap density based on Cluster EFW probe measurements: Solar wind and solar irradiation dependence
Authors: Haaland S. , Svenes K. , Lybekk B. , Pedersen A.
Published: December 2011

The plasma density above the Earth's polar caps provide crucial information about the state of the magnetosphere. This region of space is known for its tenuous plasma and extremely low plasma densities, thus making traditional measurements with particle and plasma instruments extremely difficult. A new method based on spacecraft potential measurements from the electric field instrument onboard the Cluster satellites has shown that more reliable density measurements can be obtained. In this paper, we utilize this method and present a survey of the polar cap densities and the response to changes in the solar irradiation, solar wind parameters as well as processes internal to the magnetosphere. Our observations spans a time interval of almost 10 years, thus covering almost a full solar cycle. The observations seem to confirm that solar irradiance, and thus ionization through UV absorption in the atmosphere is the most important mechanism controlling the polar cap cold plasma density. We also find positive correlations between polar cap density and solar wind density and solar wind dynamic pressure, as well as geomagnetic activity levels.
Effect of planetary boundary layer schemes on the development of intense tropical cyclones using a cloud‐resolving model
Authors: Kanada Sachie , Wada Akiyoshi , Nakano Masuo , Kato Teruyuki
Published: December 2011

We studied the role of the planetary boundary layer (PBL) in intensity and inner core structure of extremely intense tropical cyclones (TC) using a 2 km mesh nonhydrostatic atmospheric model (NHM2) developed for operational use by the Japan Meteorological Agency. To investigate the effects of the PBL on simulated TCs, we used four PBL schemes: level 2.5 and level 3 Mellor‐Yamada‐Nakanishi‐Niino closure schemes, a nonlocal scheme, and the Deardorff‐Blackadar scheme. The numerical results indicated that the subgrid‐scale mixing length determined by the PBL scheme plays a critical role in the determination of maximum TC intensity and inner core structure, even when the same expressions are provided for surface roughness lengths and the air‐sea momentum and heat transfer coefficients. Different vertical eddy‐diffusivity coefficient values derived from the PBL schemes cause differences in the TC intensity, inner core structure, and the relationship between maximum wind speed (MWS) and central pressure (CP). In particular, large vertical eddy diffusivities in lower layers (height <300 m) lead to large heat and water vapor transfers, resulting in extremely intense TCs accompanied by an upright, contracted eyewall structure. We also conducted numerical experiments using a 5 km mesh nonhydrostatic atmospheric model (NHM5) and the same PBL schemes to investigate the effect of horizontal resolution on simulated TCs. The NHM5 was insufficient to accurately represent the MWS or CP of an extremely intense TC, suggesting that NHM2 is required to simulate an extremely intense TC characterized by an upright, contracted eyewall structure.
Effects of an extreme desert dust event on the spectral ultraviolet irradiance at El Arenosillo (Spain)
Authors: Antón M. , Sorribas M. , Bennouna Y. , Vilaplana J. M. , Cachorro V. E. , Gröbner J. , Alados‐Arboledas L.
Published: December 2011

This paper analyzes the effects of an extreme Saharan dust event detected on 6 September 2007 on spectral UV irradiance recorded at El Arenosillo, South Spain. The intensity of the extreme event was detected using the aerosol optical depth (AOD) and Angström exponent series obtained by a Cimel Sun photometer operated at the study site in the framework of the Aerosol Robotic Network (AERONET). This Saharan dust event is characterized by its strong intensity, with a mean daily AOD value at 440 nm of 1.35 ± 0.40 (1.76 ± 0.03 around 13:00 UT). Additionally, a moderate decrease (∼15 Dobson units (1 DU = 2.69 × 1016 molecules cm−2)) in the total ozone column was recorded with a Brewer spectrophotometer during this episode. The spectral UV irradiance was measured from the transportable Quality Assurance of Spectral Ultraviolet Measurements in Europe (QASUME) through the development of a transportable unit reference spectroradiometer. The relative decrease of the UV irradiance at 320 nm on 6 September is about 50% (40%) with respect to days with low (moderate) aerosol loads. This attenuation slightly decreases with increasing wavelength above 315 nm. The relative differences between QASUME measurements and the spectral UV irradiance derived from the Ozone Monitoring Instrument (OMI) were calculated for the desert dust episode. This satellite instrument strongly overestimates the ground‐based UV data recorded on 6 September, with differences between 138% at 305 nm and 72% at 380 nm. Finally, the aerosol forcing efficiency (AFE) is evaluated for UV‐B (290–315 nm), UV‐A (315–400 nm), and erythemal UV (290–400 nm, weighted by the CIE spectrum), showing a notable decrease (in absolute value) with increasing solar zenith angles (SZAs). For instance, the AFE values for the harmful UV‐B irradiance change from −0.41 W/m2 per unit of AOD at 440 nm for a SZA of 30° to −0.21 W/m2 per unit of AOD for a SZA of 50°.
Evolution of a coupled marine ice sheet–sea level model
Authors: Gomez Natalya , Pollard David , Mitrovica Jerry X. , Huybers Peter , Clark Peter U.
Published: December 2011

We investigate the stability of marine ice sheets by coupling a gravitationally self‐consistent sea level model valid for a self‐gravitating, viscoelastically deforming Earth to a 1‐D marine ice sheet‐shelf model. The evolution of the coupled model is explored for a suite of simulations in which we vary the bed slope and the forcing that initiates retreat. We find that the sea level fall at the grounding line associated with a retreating ice sheet acts to slow the retreat; in simulations with shallow reversed bed slopes and/or small external forcing, the drop in sea level can be sufficient to halt the retreat. The rate of sea level change at the grounding line has an elastic component due to ongoing changes in ice sheet geometry, and a viscous component due to past ice and ocean load changes. When the ice sheet model is forced from steady state, on short timescales (<∼500 years), viscous effects may be ignored and grounding‐line migration at a given time will depend on the local bedrock topography and on contemporaneous sea level changes driven by ongoing ice sheet mass flux. On longer timescales, an accurate assessment of the present stability of a marine ice sheet requires knowledge of its past evolution.
Rigorous analysis of the parallel plate waveguide: From the transverse electromagnetic mode to the surface plasmon polariton
Authors: Leal‐Sevillano Carlos A. , Ruiz‐Cruz Jorge A. , Montejo‐Garai José R. , Rebollar Jesús M.
Published: December 2011

This paper presents an analysis of the parallel plate waveguide, based on a hybrid mode formulation. The nonideal metallic conductors of the waveguide are treated as a media characterized by an equivalent permittivity. The frequencies of interest in the presented analysis are at the terahertz band (from 300 GHz to 30 THz), and appropriate models are used for the correct characterization of metallic conductors at these frequencies. The behavior of the electromagnetic field of the fundamental mode is studied in a wide frequency range. At low frequencies (microwave regime) the fundamental mode is the well‐known transverse electromagnetic (TEM) mode; as frequency increases, the electromagnetic field changes significantly and a surface wave or surface plasmon polariton (SPP) behavior is observed at the highest frequencies of the terahertz band. This paper shows a unified formulation that explains this transformation in the electromagnetic field behavior.
Versatile multispectral microscope based on light emitting diodes
Authors: Brydegaard Mikkel , Merdasa Aboma , Jayaweera Hiran , Ålebring Jens , Svanberg Sune
Published: December 2011

We describe the development of a novel multispectral microscope, based on light-emitting diodes, capable of acquiring megapixel images in thirteen spectral bands from the ultraviolet to the near infrared. The system captures images and spectra in transmittance, reflectance, and scattering modes. We present as examples of applications ground truth measurements for remote sensing and parasitology diagnostics. The system is a general purpose scientific instrument that could be used to develop dedicated simplified instruments with optimal bands and mode selection.
Kadomtsev-Petviashvili solitons propagation in a plasma system with superthermal and weakly relativistic effects
Authors: Hafeez-Ur-Rehman  , Shah Asif , Mahmood S. , Haque Q.
Published: December 2011

Two dimensional (2D) solitons are studied in a plasma system comprising of relativistically streaming ions, kappa distributed electrons, and positrons. Kadomtsev-Petviashvili (KP) equation is derived through the reductive perturbation technique. Analytical solution of the KP equation has been studied numerically and graphically. It is noticed that kappa parameters of electrons and positrons as well as the ions relativistic streaming factor have an emphatic influence on the structural as well as propagation characteristics of two dimensional solitons in the considered plasma system. Our results may be helpful in the understanding of soliton propagation in astrophysical and laboratory plasmas, specifically the interaction of pulsar relativistic wind with supernova ejecta and the transfer of energy to plasma by intense electric field of laser beams producing highly energetic superthermal and relativistic particles [L. Arons, Astrophys. Space Sci. Lib. 357, 373 (2009); P. Blasi and E. Amato, Astrophys. Space Sci. Proc. 2011, 623; and A. Shah and R. Saeed, Plasma Phys. Controlled Fusion 53, 095006 (2011)].
The dynamics of ion with electrostatic waves in a sheared magnetic field
Authors: Yu Limin , Zhang Xianmei , Sheng Zheng-Mao
Published: December 2011

The interaction between an ion and multiple electrostatic waves propagating perpendicularly to an ambient magnetic field with shear is investigated. Based on the Lie transformation method, with the wave amplitude and the magnetic shear both as the perturbation parameters, the analytical formulas for the reduced Hamiltonian is derived and results are compared with numerical calculations of the complete equations of motion for the case of two on-resonance waves and the case of two off-resonance waves, respectively. It is found that the effect of magnetic shear drastically prevents the acceleration of an ion in both cases. This result will help us to understand the behaviors of ions in a magnetic sheared device, such as tokamak.
Large piezoresistance of single silicon nano-needles induced by non-uniaxial strain
Authors: Xiao Zhiming , She Juncong , Deng Shaozhi , Xu Ningsheng
Published: December 2011

Silicon (Si) nanostructures may play an important role in future nanoelectronics. Here, arrays of single vertically aligned Si nano-needles (SiNNs) are fabricated and found to exhibit a significant piezoresistance effect under large non-uniaxial strain. The experiments were performed by in situ manipulating of the SiNNs in a scanning electron microscope. The method enables us to determine the piezoresistance effect under the combined action of compressive and tensile strains, which is different from reported works on the piezoresistance effect of Si nanostructures under uniaxial/biaxial strains. This has given rise to an opportunity to further explore the physical origins responsible for the piezoresistance of Si. The relative change in resistivity under the non-uniaxial strain was calculated from the experimental I-V data. The results show that a greater piezoresistance effect can be achieved as compared with that of Si nanowires under uniaxial strain. We propose that the suppression of inter-valley scattering and the change of electron concentration caused by the energy band shift are the main reasons for the large piezoresistance effect.
Modeling of 10 GeV-1 TeV laser-plasma accelerators using Lorentz boosted simulations
Authors: Vay J.-L. , Geddes C. G. R. , Esarey E. , Schroeder C. B. , Leemans W. P. , Cormier-Michel E. , Grote D. P.
Published: December 2011

Modeling of laser-plasma wakefield accelerators in an optimal frame of reference [J.-L. Vay, Phys. Rev. Lett. 98, 130405 (2007)] allows direct and efficient full-scale modeling of deeply depleted and beam loaded laser-plasma stages of 10 GeV-1 TeV (parameters not computationally accessible otherwise). This verifies the scaling of plasma accelerators to very high energies and accurately models the laser evolution and the accelerated electron beam transverse dynamics and energy spread. Over 4, 5, and 6 orders of magnitude speedup is achieved for the modeling of 10 GeV, 100 GeV, and 1 TeV class stages, respectively. Agreement at the percentage level is demonstrated between simulations using different frames of reference for a 0.1 GeV class stage. Obtaining these speedups and levels of accuracy was permitted by solutions for handling data input (in particular, particle and laser beams injection) and output in a relativistically boosted frame of reference, as well as mitigation of a high-frequency instability that otherwise limits effectiveness.
Mean-field Ohm’s law and coaxial helicity injection in force-free plasmas
Authors: Weening R. H.
Published: December 2011

A theoretical analysis of steady-state coaxial helicity injection (CHI) in force-free plasmas is presented using a parallel mean-field Ohm’s law that includes resistivity η and hyper-resistivity Λ terms. Using Boozer coordinates, a partial differential equation is derived for the time evolution of the mean-field poloidal magnetic flux, or magnetic Hamiltonian function, from the parallel mean-field Ohm’s law. A general expression is obtained from the mean-field theory for the efficiency of CHI current drive in force-free plasmas. Inductances of internal energy, magnetic helicity, and poloidal magnetic flux are used to characterize axisymmetric plasma equilibria that have a model current profile. Using the model current profile, a method is suggested to determine the level of magnetohydrodynamic activity at the magnetic axis and the consequent deviation from the completely relaxed Taylor state. The mean-field Ohm’s law model suggests that steady-state CHI can be viewed most simply as a boundary layer problem.
Emission spectroscopy of divalent-cation-doped GaN photocatalysts
Authors: Hirai Takeshi , Harada Takashi , Ikeda Shigeru , Matsumura Michio , Saito Nobuo , Nishiyama Hiroshi , Inoue Yasunobu , Harada Yoshiyuki , Ohno Nobuhito , Maeda Kazuhiko , Kubota Jun , Domen Kazunari
Published: December 2011

Photoluminescence (PL) and time-resolved photoluminescence (TRPL) spectra of GaN particles doped with divalent cations (Mg2+, Zn2+, and Be2+), which promote photocatalytic overall water splitting, were investigated. The PL and TRPL spectra were mainly attributed to donor-acceptor pair recombination between the divalent cation dopants and divalent anion impurities (O2− and S2−) unintentionally introduced from raw materials, which form acceptor and donor levels, respectively. These levels are likely to provide holes and electrons required for photocatalytic reactions, contributing to the photocatalytic activity of the GaN-based photocatalysts for overall water splitting.
Effects of the interaction potential and hydrodynamic interaction on the diffusion-influenced reaction rates
Authors: Son Chang Yun , Lee Sangyoub
Published: December 2011

Recently, we proposed an accurate analytic expression for the diffusive propagator of a pair of particles under a central interaction potential and hydrodynamic interaction, and derived the rate expressions for fully diffusion-controlled geminate and bimolecular reactions. In this work, we present a still more accurate propagator expression, and extend the theory to the partially diffusion-controlled cases with various types of interaction potentials, including the screened Coulomb potential and the potential of mean force due to solvation. We evaluate the accuracies of our theory and other competing theories against exact numerical results. It is shown that the improved rate expressions provide near exact results for most types of interaction potentials.
Mach-Zehnder interferometric device for spin filtering in a GaAs/AlGaAs electron gas
Authors: Santos Benjamin , Medina Ernesto , López Alexander , Berche Bertrand
Published: December 2011

A spin filtering device using quantum spin interference is theoretically proposed in a GaAs/AlGaAs electron gas that has both Rashba and Dresselhaus spin-orbit couplings. The device achieves polarized electron currents by separating spin up and spin down components without a magnetic field gradient. We find two broad spin filtering regimes, one where the interferometer has symmetrical arms, where a small magnetic flux is needed to achieve spin separation, and the other with asymmetric arms where the change in path length renders an extra phase emulating the effects of a magnetic field. We identify operating points for the device where optimal electron polarization is achieved within value ranges found in a 2D electron gas. Both device setups apply for arbitrary incoming electron polarization and operate at broad energy ranges within the incoming electron band.
Interface engineering using ferromagnetic nanoparticles for enhancing pinning in YBa2Cu3O7−δ thin film
Authors: Jha Alok K. , Khare Neeraj , Pinto R.
Published: December 2011

Thin films of YBCO have been deposited on bare and La0.67Sr0.33MnO3 (LSMO) nanoparticle decorated single crystal SrTiO3 (STO) substrates. The effect of ferromagnetic LSMO nanoparticles, present at the substrate/film interface, on the superconducting properties of YBa2Cu3O7−δ (YBCO) thin film has been investigated by temperature dependent magnetization studies. The YBCO thin film on LSMO decorated STO substrate shows significant improvement in the critical current density and pinning force density as compared to the YBCO thin film deposited on the undecorated substrate, and this improvement is more significant at higher applied magnetic field. The presence of LSMO nanoparticles at YBCO/STO interface seems to introduce structural defects, which might be in the form of threading dislocations along the c-axis acting as correlated pinning centers leading to improved flux pinning properties of the YBCO thin film. The LSMO nanoparticles are ferromagnetic, which can also act as magnetic pinning centers and may result in the enhancement of flux pinning properties of the YBCO thin film deposited on the LSMO decorated STO substrate.
Apparatus for laser-assisted electron scattering in femtosecond intense laser fields
Authors: Kanya Reika , Morimoto Yuya , Yamanouchi Kaoru
Published: December 2011

An apparatus for observation of laser-assisted electron scattering (LAES) in femtosecond intense laser fields was developed. The unique apparatus has three essential components, i.e., a photocathode-type ultrashort pulsed-electron gun, a toroidal-type electron energy analyzer enabling simultaneous detection of energy and angular distributions of scattered electrons with high efficiency, and a high repetition-rate data acquisition system combined with a high power 5 kHz Ti:sapphire laser system. These advantages make extremely weak femtosecond-LAES signals distinguishable from the huge elastic scattering signals. A precise method for securing a spatial overlap between three beams, that is, an atomic beam, an electron beam, and a laser beam, and synchronization between the electron and laser pulses is described. As a demonstration of this apparatus, an electron energy spectrum of the LAES signals with 1.4 × 1012 W/cm2, 795 nm, 50 fs laser pulses was observed, and the detection limit and further improvements of the apparatus are examined.
Structural phases in non-additive soft-disk mixtures: Glasses, substitutional order, and random tilings
Authors: Widmer-Cooper Asaph , Harrowell Peter
Published: December 2011

Relaxation of the additivity condition on the interaction length between unlike species in a binary mixture of soft disks opens up a rich variety of structures in both crystal and amorphous states with an associated diverse range of relaxation dynamics. We report on MD simulation studies of binary soft disks with negative deviations from additivity that include evidence of accumulation of crystal-like structures in metastable liquids prior to crystallization and the occurrence of a liquid to random-tiling transition.
Anomalous transport and thermal properties of NiTi and with Cu and Fe-doped shape memory alloys near the martensitic transition
Authors: Ingale B. D. , Wei W. C. , Chang P. C. , Kuo Y. K. , Wu S. K.
Published: December 2011

The temperature dependent electrical and thermal properties including electrical resistivity (ρ), specific heat (CP), Seebeck coefficient (S) and thermal conductivity (κ) have been studied for the polycrystalline NiTi, Ti50Ni40Cu10 and Ti50Ni48.5Fe1.5 shape memory alloys from 10–400 K. It was found that the electrical resistivity and Seebeck coefficient exhibit a typical metallic behavior throughout the temperature range investigated. A significant thermal hysteresis between warming and cooling was observed in all the three alloys which is a manifestation of the first-order nature of martensitic transitions. Our results indicate the presence of two stage martnesite transformations, i.e. B2 → B19  →  B19′ for Ti50Ni40Cu10 while B2 → R → B19′ for NiTi and Ti50Ni48.5Fe1.5 alloys. An analysis on the measured thermal conductivity reveals that the anomalous feature in κ at the B19 ↔ B19′ transformation for Ti50Ni40Cu10 is essentially attributed to the electronic contribution, while an enormously large peak in warming run observed at the B19 → B2 transformation is due to the change in lattice thermal conductivity.
Fe-spin reorientation in PrFeAsO: Evidences from resistivity and specific heat studies
Authors: Bhoi D. , Mandal P. , Choudhury P. , Pandya S. , Ganesan V.
Published: December 2011

We report the magnetic field dependence of resistivity (ρ) and specific heat (C) for the non-superconducting PrFeAsO compound. Our study shows a hitherto unobserved anomaly at TSR in the resistivity and specific heat data, which arises as a result of the interplay of antiferromagnetic (AFM) Pr and Fe sublattices. Below the AFM transition temperature (TNPr), Pr moment orders along the crystallographic c axis and its effect on the iron subsystem causes a reorientation of the ordered in-plane Fe moments in a direction out of the ab plane. Application of magnetic field introduces disorder in the AFM Pr sublattice, which, in turn, reduces the out-of-plane Pr-Fe exchange interaction responsible for Fe spin reorientation. Both in ρ(T) and d(C/T)/dT curves, the peak at TSR broadens with the increase of H due to the introduction of the disorder in the AFM Pr sublattice by magnetic field. In the ρ(T) curve, the peak shifts toward lower temperature with H and disappears above 6 T, while in the d(C/T)/dT curve, the peak remains visible up to 14 T. The broadening of the anomaly at TNPr in C(T) with increasing H further confirms that magnetic field induces disorder in the AFM Pr sublattice.
Multiple stepwise pattern for potential of mean force in unfolding the thrombin binding aptamer in complex with Sr2+
Authors: Yang Changwon , Jang Soonmin , Pak Youngshang
Published: December 2011

Using all-atom molecular dynamics simulation in conjunction with umbrella sampling, we obtained the unfolding free energy and the force extension profiles of the thrombin binding DNA aptamer (15-TBA) in complex with Sr2+ (Protein Data Bank code: 1RDE). The resulting potential of mean force (PMF) displays a multiple stepwise pattern with distinct plateau regions. The detailed analysis of the simulation result indicated that each plateau was created by the interplay of the metal ion interacting with self-arranging guanine bases and the successive uptakes of water molecules. The current PMF simulation provides a quantitative description of the unfolding process of 15-TBA DNA driven by stretching and gives molecular insight on its detailed changes of base pair interactions in the presence of the metal cation.
Band-gap narrowing in α-(CrxFe1-x)2O3 solid-solution films
Authors: Mashiko Hisanori , Oshima Takayoshi , Ohtomo Akira
Published: December 2011

We report on structural and optical properties for the (0001)-oriented α-(CrxFe1-x)2O3 (0 ≤ x ≤ 1) epitaxial films prepared on c-sapphire substrates by using pulsed-laser deposition. Pure corundum phase with atomically flat surface was obtained in the entire composition range. Optical absorption spectra for the films with 0.2 < x < 0.9 showed a nearly constant band-gap (1.7 eV), which is narrower than those of α-Fe2O3 (2.1 eV) and α-Cr2O3 (3.0 eV). The result suggests that the band-gap narrowing arises from a type-II band alignment of these oxides and the fundamental band-gap lies between the Cr t2g and O 2p occupied states and the Fe t2g* empty state.