bluuebunny/crossref_metadata_2025 huggingface dataset:
Explaining the longitudinal association between puberty and depression: Sex differences in the mediating effects of peer stress
Authors: Conley Colleen S. , Rudolph Karen D. , Bryant Fred B.
Published: April 2012

This research investigated whether exposure to peer stress serves as one pathway through which pubertal development contributes to depression over time, differentially for girls and boys. Youth (N= 149; 9.6–14.8 years) and their caregivers provided information at two waves, 1 year apart, on puberty (Wave 1), peer stress (occurring between Waves 1 and 2), and depression (Waves 1 and 2). Structural equation modeling analyses examined sex differences in the extent to which peer stress mediated the impact of pubertal status and timing on subsequent depression (i.e., tests of moderated mediation). Significant sex-moderated mediation was found for both pubertal status and timing. As indicated by moderate effect proportions, in girls, heightened peer stress partially mediated the longitudinal association between (a) more advanced pubertal status and depression; and (b) linear, but not curvilinear, pubertal timing (i.e., earlier maturation) and depression. This research contributes to our growing understanding of the interplay among physical, psychological, and social processes involved in the sex difference in adolescent depression.
Small vessel cerebrovascular disease in older adults
Authors: Slavin Helen , McManus Julie , Stott David J
Published: April 2012

‘Cerebral small vessel disease’ is common in older adults and is an important cause of morbidity, functional impairment and cognitive decline. Small vessel disease is a collective term used to describe a number of underlying pathological processes and neuroimaging findings, such as lacunar infarcts, white matter lesions and microhaemorrhages.

With readily available neuroimaging, diagnostic accuracy has improved; however, the management of small vessel disease and prevention of cognitive decline remains uncertain. Treatment of conventional vascular risk factors may be appropriate, but future research is required to provide definitive answers. We have conducted a comprehensive literature review of cerebral small vessel disease in older adults. This highlights the clinical sequelae and underlying pathological processes, whilst discussing novel diagnostic neuroimaging and therapeutic strategies.
Enlarged right ventricular size at 11 years’ follow-up after closure of secundum-type atrial septal defect in children
Authors: de Koning Wilfred B. , van Osch-Gevers Lennie M. , Robbers-Visser Danielle , van Domburg Ron T. , Bogers Ad J.J.C. , Helbing Willem A.
Published: April 2012

Background

The fate of right ventricular dimensions after surgical closure of secundum-type atrial septal defects remains unclear. The objectives of this study were to assess ventricular dimensions, exercise capability, and arrhythmias of patients operated for secundum-type atrial septal defect and compare the results with those in healthy references.

Methods

A total of 78 consecutive patients underwent surgical closure for a secundum-type atrial septal defect between 1990 and 1995. In all, 42 patients were included and underwent a cross-sectional evaluation including echocardiography, magnetic resonance imaging, exercise testing, and 24-hour ambulatory electrocardiography. Patients were matched with healthy controls for gender, body surface area, and age.

Results

The mean age at surgery was 4.6 plus or minus 2.8 years, and the mean age at follow-up was 16 plus or minus 3 years. There were no residual intracardiac lesions. The mean right ventricular end-systolic volume was significantly larger in patients (142 ± 26 millilitres) than in references (137 ± 28 millilitres; p = 0.04). In 25% of the patients, right ventricular end-systolic volume was larger than the 95th percentile for references. No relevant arrhythmias were detected. Exercise testing did not reveal differences with healthy references: maximal power (169 ± 43 Watt patients versus 172 ± 53 controls; p = 0.8), maximal oxygen uptake (38 ± 8 versus 41 ± 13 millilitres per minute per kilogram; p = 0.1).

Comment

After surgical closure of secundum-type atrial septal defect, right ventricular end-systolic volume is increased. These findings have no impact on rhythm status or exercise capacity at this stage of follow-up, but may have implications for the timing of surgery or the technique of closure if confirmed in longer follow-up.
An evaluation of an operations research project to reduce childhood stunting in a food-insecure area in Ethiopia
Authors: Fenn Bridget , Bulti Assaye T , Nduna Themba , Duffield Arabella , Watson Fiona
Published: April 2012

Objective

To determine which interventions can reduce linear growth retardation (stunting) in children aged 6–36 months over a 5-year period in a food-insecure population in Ethiopia.

Design

We used data collected through an operations research project run by Save the Children UK: the Child Caring Practices (CCP) project. Eleven neighbouring villages were purposefully selected to receive one of four interventions: (i) health; (iii) nutrition education; (iii) water, sanitation and hygiene (WASH); or (iv) integrated comprising all interventions. A comparison group of three villages did not receive any interventions. Cross-sectional surveys were conducted at baseline (2004) and for impact evaluation (2009) using the same quantitative and qualitative tools. The primary outcome was stunted growth in children aged 6–36 months measured as height (or length)-for-age Z-scores (mean and prevalence). Secondary outcomes were knowledge of health seeking, infant and young child feeding and preventive practices.

Setting

Amhara, Ethiopia.

Subjects

Children aged 6–36 months.

Results

The WASH intervention group was the only group to show a significant increase in mean height-for-age Z-score (+0·33, P = 0·02), with a 12·1 % decrease in the prevalence of stunting, compared with the baseline group. This group also showed significant improvements in mothers’ knowledge of causes of diarrhoea and hygiene practices. The other intervention groups saw non-significant impacts for childhood stunting but improvements in knowledge relating to specific intervention education messages given.

Conclusions

The study suggests that an improvement in hygiene practices had a significant impact on stunting levels. However, there may be alternative explanations for this and further evidence is required.
Fruit and vegetable intake and bone mass in Chinese adolescents, young and postmenopausal women
Authors: Li Jing-Jing , Huang Zhen-Wu , Wang Ruo-Qin , Ma Xiao-Ming , Zhang Zhe-Qing , Liu Zen , Chen Yu-Ming , Su Yi-Xiang
Published: April 2012

Objective

Previous studies showed an inconsistent association of fruit and vegetable consumption with bone health. We assessed the associations in Chinese adolescents, young and postmenopausal women.

Design

A cross-sectional study conducted in China during July 2009 to May 2010.

Setting

Bone mineral density (BMD) and content (BMC) at the whole body, lumbar spine and left hip were measured with dual-energy X-ray absorptiometry. Dietary intakes were assessed using an FFQ. All these values were separately standardized intoZ-scores in each population subgroup.

Subjects

One hundred and ten boys and 112 girls (11–14 years), 371 young women (20–34 years, postpartum within 2 weeks) and 333 postmenopausal women (50–70 years).

Results

After adjustment for potential covariates, analysis of covariance showed a significantly positive association between fruit intake and BMD and BMC in all participants combined (P-trend: < 0·001 to 0·002). BMDZ-score increased by 0·25 (or 2·1 % of the mean), 0·22 (3·5 %), 0·23 (3·0 %) and 0·25 (3·5 %), and BMCZ-score increased by 0·33 (5·7 %), 0·25 (5·8 %), 0·34 (5·9 %) and 0·29 (4·7 %), at the total body, lumbar spine, total hip and femoral neck in participants belonging to the top tertile compared with the bottom tertile of fruit intake (allP< 0·05), respectively. There was no significant association between vegetable intake and bone mass at all bone sites studied except for total body BMD (P= 0·030). Relatively more pronounced effects were observed in boys and postmenopausal women.

Conclusion

Our findings add to the existing evidence that fruits and vegetables may have a bone sparing effect.
Escitalopram reduces attentional performance in anxious older adults with high-expression genetic variants at serotonin 2A and 1B receptors
Authors: Lenze Eric J. , Dixon David , Nowotny Petra , Lotrich Francis E. , Doré Peter M. , Pollock Bruce G. , Hinrichs Anthony L. , Butters Meryl A.
Published: April 2012

Older adults are among the most vulnerable to adverse cognitive effects of psychotropic medications and, therefore, the personalization of psychotropic treatment based on adverse drug reactions in this demographic is of great importance. We examined changes on neuropsychological tests of attention attributable to selective serotonin reuptake inhibitor (SSRI) treatment in anxious older adults. We also examined whether variation in serotonin receptor genes was associated with reduced attentional performance with SSRIs. We examined change from pre- to post-treatment in two attention measures – digit span and coding – in 133 adults aged ⩾60 yr with generalized anxiety disorder in a 12-wk trial of escitalopram vs. placebo. We also examined attentional change in relation to genetic variability in four central serotonin receptors: the serotonin transporter and serotonin 1A, 2A and 1B receptors. Digit span scores were significantly lowered in patients receiving escitalopram relative to placebo, indicating reduced attentional performance attributable to the SSRI. Individuals with high-transcription variants in the receptors 5-HTR2A rs6311 and 5-HTR1B rs11568817 had greater reductions in attention with SSRI treatment compared to placebo. We conclude that SSRIs reduce attention in older adults, particularly in those with high-expression genetic variants at the serotonin 2A and 1B receptors. Analysing neuropsychological changes with SSRIs in relation to genetic variation in the serotonin system may be a useful strategy for detecting subgroups of older adults who are more susceptible to side-effects of SSRIs. These results, if confirmed, could lead to the personalization of SSRI use to reduce adverse neurocognitive effects.
A pilot study on the effects and feasibility of compassion-focused expressive writing in Day Hospice patients
Authors: Imrie Susan , Troop Nicholas A.
Published: April 2012

Objective:

Research has found that writing about stress can confer physical and psychological health benefits on participants and that adopting a self-compassionate stance may have additional benefits. This pilot study evaluated a self-compassionate expressive writing intervention in a Day Hospice setting.

Method:

Thirteen patients with life-limiting illnesses wrote on two occasions about recent stressful experiences. Half also received a self-compassion instruction for their writing. Outcome measures were taken at baseline and one week after the second writing session, and text analysis was used to identify changes in the types of words used, reflecting changes in psychological processes.

Results:

Patients given the self-compassion instruction increased in their self-soothing and self-esteem in contrast to patients in the stress-only condition. Happiness broadly increased in both groups although reported levels of stress generally increased in patients given the self-compassion instruction but decreased in patients in the stress-only condition. Those given the self-compassion instruction also increased in their use of causal reasoning words across the two writing sessions compared with those in the stress-only condition.

Significance of Results:

Expressive writing appears to be beneficial in patients at a hospice and was viewed as valuable by participants. The inclusion of a self-compassion instruction may have additional benefits and a discussion of the feasibility of implementing expressive writing sessions in a Day Hospice is offered.
The enduring relevance of the model Platonism critique for economics and public policy
Authors: ARNOLD DARRELL , MAIER-RIGAUD FRANK P.
Published: April 2012

The article briefly introduces Hans Albert and the basic elements of his critique of neoclassical economics as a form of ‘model Platonism’. The two most important elements of his general methodological critique of economics – namely the institutional vacuum inherent in much economic modelling and its unrealistic assumptions about behaviour – are introduced. It is argued that these specific critiques have been taken up with varying degrees of success in areas of economic research such as institutional economics and in behavioural and experimental research programmes. However, the fundamental methodological gist of his critique remains as pertinent to mainstream economics as it was when originally formulated. The influence of ‘model Platonic’ thinking remains pervasive in academia and also in public policy.
Spatial upscaling using thematic maps: An analysis of uncertainties in permafrost soil carbon estimates
Authors: Hugelius Gustaf
Published: April 2012

Studies of periglacial regions confirm their importance in the global carbon (C) cycle, but estimates of ecosystem C storage or green‐house gas fluxes from these remote areas are generally poorly constrained and quantitative estimates of upscaling uncertainties are lacking. In this study, a regional database describing soil organic carbon (SOC) storage in periglacial terrain (European Russian Arctic) was used to evaluate spatial upscaling from point measurements using thematic maps. The selection of classes for upscaling and the need for replication in soil sampling were statistically evaluated. Upscaling using a land cover classification and a soil map estimated SOC storage to 48.5 and 47.0 kg C m−2, respectively with 95% confidence intervals (CI) within ±8%. When corrected for spatial errors in the LCC upscaling proxy, SOC was estimated to 46.5 kg C m−2 with a 95% CI reflecting propagated variance from both natural variability and spatial errors of ±11%. Artificially decreasing the size of the database used for upscaling showed that relatively stable results could be achieved with lower replication in some upscaling classes. Decreased spatial resolution for upscaling from 30 m to 1 km had little impact on SOC estimates in this region, but classification accuracy was dramatically reduced and land cover classes show different, sometimes nonlinear, responses to scale. The methods and recommendations presented here can provide guidelines for any future study where point observations of a variable are upscaled using remotely sensed thematic maps or classifications and potential applications for circum‐arctic studies are discussed. For future upscaling studies at large geographic scales, a priori determination of sample sizes and tests to insure unimodal and statistically independent samples are recommended. If these prerequisites are not fulfilled, classes may be merged or subdivided prior to upscaling.
Effects of solar X‐ray flares in the E region ionosphere of Mars: First model results
Authors: Haider S. A. , McKenna‐Lawlor S. M. P. , Fry C. D. , Jain Rajmal , Joshipura K. N.
Published: April 2012

We have used radio occultation data obtained from Mars Global Surveyor (MGS) at high latitudes (65.3°–65.6°N, 69.3°–69.6°N and 76.4°–77.5°N) to study the effects of X‐ray flares and CMEs on Total Electron Content (TEC) in the E region of the Martian ionosphere in response to solar events that occurred on 29 and 31 May 2003 and on 17 January and 13 May 2005. Modeling of flare induced solar X‐ray fluxes, ion production rates, electron densities and TEC are carried out, in each case based on GOES data. The estimated TEC values are compared with the in situ MGS observations. It is found that solar flare caused enhancements in the TEC of Mars by a factor of ∼5. Also, a 3D kinetic solar wind model (Hakamada‐Akasofu‐Fry Version 2/HAFv.2) is used to predict the arrivals of CME shocks at Mars associated with the flare event of May 2005. These predicted shock arrivals were associated with in situ enhancements in TEC by a factor of ∼2.
Modeling of stress‐dependent static and dynamic moduli of weak sandstones
Authors: Li Liming , Fjær Erling
Published: April 2012

Static and dynamic moduli of a sandstone may be different and stress‐sensitive. Knowledge about this is important for the interpretation of seismic data and sonic logs. We use a numerical model which is based on the discrete element method (DEM) to study the static and the dynamic mechanical behavior of weak sandstones. We developed a constitutive contact law and implemented it into the DEM model in order to properly simulate the deformation of weak sandstones. The contact law includes the effect of nonlinear elasticity and plasticity at grain contacts. The DEM model can also capture the effect of the closing of pre‐existing cracks, the formation of new cracks and slip at uncemented grain contacts due to stress alteration. Using such a model, we simulated sandstone specimens under laboratory experimental conditions. We calculated the static and the dynamic moduli of the DEM model at different stress states. The modeling results qualitatively agree with some published laboratory observations. By applying different stress paths and stress histories, we studied how the moduli were influenced by the stress state, stress path, and stress history. In particular, the simulations show the growing difference between the static and the dynamic moduli as failure is approached. The simulations thus support the assumption that theoretical insight in the grain‐scale deformation mechanisms helps to understand and explain the difference between static and dynamic moduli, as well as for the failure process.
Changes of the Antarctic ozone hole: Controlling mechanisms, seasonal predictability, and evolution
Authors: Salby Murry L. , Titova Evgenia A. , Deschamps Lilia
Published: April 2012

The ozone hole changes considerably from one year to the next. It varies between conditions in which springtime ozone is strongly depleted to others in which ozone is only weakly depleted. Those changes are shown to closely track anomalous planetary wave forcing of the residual circulation. The strong coherence with planetary wave forcing is consistent with similar coherence of springtime temperature, which modulates Polar Stratospheric Cloud (PSC). By controlling the lifetime of PSC, anomalous wave forcing determines the net activation of chlorine and bromine and, hence, springtime depletion of ozone during individual years. The strong coherence with planetary wave forcing affords long‐range predictability. It supports a seasonal forecast of springtime depletion, which, through the ozone mass deficit, perturbs ozone across much of the Southern Hemisphere during subsequent months of summer. Conditioned upon wintertime wave structure, a hindcast of springtime depletion faithfully predicts the anomalous ozone observed. A reliable forecast of tropospheric planetary waves would thus enable springtime depletion to be predicted. The current evolution of Antarctic ozone is dominated by dynamically‐induced changes. Representing its climate variability, those large changes obscure the more gradual evolution of springtime depletion, like that associated with the decline of chlorine. The strong dependence on planetary wave forcing, however, enables dynamically‐induced changes of ozone to be identified accurately. Removing them unmasks the secular variation of Antarctic ozone, the part coherent over a decade and longer. Independent of dynamically‐induced changes, that component discriminates to changes associated with stratospheric composition. It reveals a gradual but systematic rebound over the last decade. The upward trend is shown to be robust, significant at the 99.5% level. Uncertainty in this trend is thus small enough to make the probability of it arising through chance alignment of error less than 0.5%. The discriminated component mirrors the decline of effective stratospheric chlorine, representing a gradual return of springtime ozone toward its level in 1980 of 10–15%. It enables Antarctic ozone to be tracked relative to changes of chlorine, CO2, and other features of climate more reliably than is otherwise possible.
On hurricane parametric wind and applications in storm surge modeling
Authors: Lin Ning , Chavas Daniel
Published: April 2012

This study revisits the parametric modeling of the hurricane surface wind field composed of the storm vortex and the environmental background flow. First, we investigate the parametric representation of the surface background wind by analyzing its empirical relationship with storm movement. A marked deceleration and counter‐clockwise rotation of the surface background wind from the storm translation vector is detected, a result predicted by the Ekman theory but rarely applied in wind and surge modeling. Then, we examine the various parameters used to model the wind field and, through numerical simulations, quantify their induced uncertainties in the extreme wind and surge estimates at two coastal sites. Our analyses show that, over the range of accepted values and methods in the literature, the local wind and surge estimates are most sensitive to uncertainties in the surface wind reduction factor and storm wind profile but less sensitive to uncertainties in other wind parameters, such as inflow angle and surface background wind (varying in the observed range). The surge is more sensitive than the wind to uncertainties in the wind parameters, and these sensitivities are comparable to the sensitivity of the surge to the uncertainty in the sea surface drag coefficient. We also find that some commonly used wind parameters unsupported by theory or observations can induce significant errors in the wind and surge estimates. The results of this study provide new insights and references for future hurricane wind and surge analysis.
Sharpening our thinking about polar cap ionospheric patch morphology, research, and mitigation techniques
Authors: Carlson Herbert C.
Published: April 2012

Since polar cap patches were discovered, their nature, physics, and impact on navigation and communication signals has been repeatedly addressed. Both terminology and inference of physical processes from diverse instruments have introduced confusion. Poleward moving auroral form is a morphological descriptor but cannot be equated to an island of high‐density plasma. Particle precipitation produces low‐density patches, but high‐density patches derive from solar produced plasma. The challenge of patches is finding the dominant mechanism for chopping entering ionization into islands (∼100–1000 km in size). Velocity‐dependent recombination physics is valid in principle but not relevant to patches formed in at least the European sector. Most patches are formed by transient magnetic reconnection events. While the plasma is at too high an altitude for the strong velocity shears to erode plasma densities, the shears become the dominant plasma structuring mechanism until the initial magnetic tension force is relaxed. Initial patch structuring is not by gradient drift as believed for decades but rather by the shear driven instability, impacting mitigation techniques. Large‐scale shears, driven to 2–3 km/s, impact satellite drag through thermospheric heating. The study here is intended to sharpen understanding of patches for future research and development of techniques for mitigation of their effects on navigation and other systems dependent on receiving radio frequency signals from satellites and understanding reconnection driven impact on thermospheric density and satellite drag.
World ocean heat content and thermosteric sea level change (0–2000 m), 1955–2010
Authors: Levitus S. , Antonov J. I. , Boyer T. P. , Baranova O. K. , Garcia H. E. , Locarnini R. A. , Mishonov A. V. , Reagan J. R. , Seidov D. , Yarosh E. S. , Zweng M. M.
Published: April 2012

We provide updated estimates of the change of ocean heat content and the thermosteric component of sea level change of the 0–700 and 0–2000 m layers of the World Ocean for 1955–2010. Our estimates are based on historical data not previously available, additional modern data, and bathythermograph data corrected for instrumental biases. We have also used Argo data corrected by the Argo DAC if available and used uncorrected Argo data if no corrections were available at the time we downloaded the Argo data. The heat content of the World Ocean for the 0–2000 m layer increased by 24.0 ± 1.9 × 1022 J (±2S.E.) corresponding to a rate of 0.39 W m−2 (per unit area of the World Ocean) and a volume mean warming of 0.09°C. This warming corresponds to a rate of 0.27 W m−2 per unit area of earth's surface. The heat content of the World Ocean for the 0–700 m layer increased by 16.7 ± 1.6 × 1022 J corresponding to a rate of 0.27 W m−2(per unit area of the World Ocean) and a volume mean warming of 0.18°C. The World Ocean accounts for approximately 93% of the warming of the earth system that has occurred since 1955. The 700–2000 m ocean layer accounted for approximately one‐third of the warming of the 0–2000 m layer of the World Ocean. The thermosteric component of sea level trend was 0.54 ± .05 mm yr−1 for the 0–2000 m layer and 0.41 ± .04 mm yr−1 for the 0–700 m layer of the World Ocean for 1955–2010.
Areas of permanent shadow in Mercury's south polar region ascertained by MESSENGER orbital imaging
Authors: Chabot Nancy L. , Ernst Carolyn M. , Denevi Brett W. , Harmon John K. , Murchie Scott L. , Blewett David T. , Solomon Sean C. , Zhong Ellen D.
Published: April 2012

Radar‐bright features near Mercury's poles have been postulated to be deposits of water ice trapped in cold, permanently shadowed interiors of impact craters. From its orbit about Mercury, MESSENGER repeatedly imaged the planet's south polar region over one Mercury solar day, providing a complete view of the terrain near the south pole and enabling the identification of areas of permanent shadow larger in horizontal extent than approximately 4 km. In Mercury's south polar region, all radar‐bright features correspond to areas of permanent shadow. Application of previous thermal models suggests that the radar‐bright deposits in Mercury's south polar cold traps are in locations consistent with a composition dominated by water ice provided that some manner of insulation, such as a thin layer of regolith, covers many of the deposits.
Is Mercury a volatile‐rich planet?
Authors: McCubbin Francis M. , Riner Miriam A. , Vander Kaaden Kathleen E. , Burkemper Laura K.
Published: April 2012

Data returned from the gamma‐ray spectrometer onboard the Mercury Surface, Space Environment, Geochemistry, and Ranging (MESSENGER) spacecraft have been interpreted to say that Mercury is a volatile‐rich planet (elevated K/Th and K/U), which is important given its heliocentric distance. The MESSENGER X‐ray spectrometer provided chemical information from the surface of Mercury which we used to calculate an average surface composition for the regions analyzed. The high S abundance and low FeO abundance of the surface indicates that the oxygen fugacity of the Mercurian interior is very reducing (−6.3 to −2.6 logfO2units below the iron‐wüstite buffer). At these low oxygen fugacities, elements that are typically considered lithophile can become more siderophile or chalcophile. We review available metal/silicate partitioning data for K and U to show that Mercury's volatile inventory is still an open question, and additional experiments investigating metal/silicate partitioning at the conditions of Mercury's core formation are needed.
Ex vivo functional analysis, expansion and adoptive transfer of cytomegalovirus‐specific T‐cells in patients with glioblastoma multiforme
Authors: Crough Tania , Beagley Leone , Smith Corey , Jones Linda , Walker David G , Khanna Rajiv
Published: April 2012

The frequent detection of human cytomegalovirus (CMV) antigens in glioblastoma multiforme (GBM) has raised the possibility of exploiting CMV‐specific T‐cell immunotherapy to control this disease in CMV‐‐seropositive patients. Here, we have conducted a comprehensive ex vivo profiling of CMV‐specific CD8+ T‐cell responses in a cohort of GBM patients. Of the patients analyzed, approximately half exhibited serological evidence of past infection with CMV. Although no CMV‐specific CD8+ T‐cell responses could be detected in the serologically negative GBM patients, virus‐specific CD8+ T‐cell responses were detected in all seropositive GBM patients. Using major histocompatibility complex‐peptide multimers, the frequency of CMV‐specific T‐cells in the patients detected ranged from 0.1 to 22% of CD8+ T‐cells and a high proportion of these cells were positive for the human natural killer‐1 glycoprotein CD57. Furthermore, ex vivo polychromatic functional analysis of the CMV‐specific T‐cells from GBM patients revealed that large proportions of these cells were unable to produce multiple cytokines (macrophage inflammatory protein (MIP)‐1β, tumor necrosis factor (TNF)α and interferon (IFN)γ) and displayed limited cytolytic function (CD107a mobilization) following stimulation with CMV peptide epitopes. However, in vitro stimulation with CMV peptide epitopes in the presence of γC cytokine dramatically reversed the polyfunctional profile of these antigen‐specific T‐cells with high levels of MIP‐1β, TNFα, IFNγ and CD107a mobilization. Most importantly, adoptive transfer of these in vitro‐expanded T‐cells in combination with temozolomide (TMZ) therapy into a patient with recurrent GBM was coincident with a long‐term disease‐free survival. These studies provide an important platform for a formal assessment of combination therapies based on CMV‐specific T‐cells and TMZ for recurrent GBM.
Vibrational Fano resonances in dipole-bound anions
Authors: Edwards Stephen T. , Johnson Mark A. , Tully John C.
Published: April 2012

This paper explores Fano resonances due to non-adiabatic coupling of vibrational modes and the electron continuum in dipole-bound anions. We adopt a simple one-electron model consisting of a point dipole and an auxiliary potential to represent the electron interaction with the neutral core. Nuclear motion is added by assuming that harmonic vibrations modulate the dipole moment. When the model is parameterized to simulate key features of the water tetramer anion, the resultant photodetachment lineshape closely resembles that observed experimentally and analyzed as a Fano resonance with a parameter q close to −1. Other parameterizations are explored for the model and it is found that large changes in the auxiliary potential are required to change the sign of q. This is consistent with the experimental finding that q is negative for all water cluster sizes studied.
Inhomogeneous charge transfer within monolayer zinc phthalocyanine absorbed on TiO2(110)
Authors: Yu Shun , Ahmadi Sareh , Sun Chenghua , Adibi Pooya Tabib Zadeh , Chow Winnie , Pietzsch Annette , Göthelid Mats
Published: April 2012

The d-orbital contribution from the transition metal centers of phthalocyanine brings difficulties to understand the role of the organic ligands and their molecular frontier orbitals when it adsorbs on oxide surfaces. Here we use zinc phthalocyanine (ZnPc)/TiO2(110) as a model system where the zinc d-orbitals are located deep below the organic orbitals leaving room for a detailed study of the interaction between the organic ligand and the substrate. A charge depletion from the highest occupied molecular orbital is observed, and a consequent shift of N1s and C1s to higher binding energy in photoelectron spectroscopy (PES). A detailed comparison of peak shifts in PES and near-edge X-ray absorption fine structure spectroscopy illustrates a slightly uneven charge distribution within the molecular plane and an inhomogeneous charge transfer screening between the center and periphery of the organic ligand: faster in the periphery and slower at the center, which is different from other metal phthalocyanine, e.g., FePc/TiO2. Our results indicate that the metal center can substantially influence the electronic properties of the organic ligand at the interface by introducing an additional charge transfer channel to the inner molecular part.
Critical exponents from parallel plate geometries subject to periodic and antiperiodic boundary conditions
Authors: da Silva José B. , Leite Marcelo M.
Published: April 2012

We introduce a renormalized one-particle irreducible, 1PI, vertex part scalar field theory setting in momentum space to computing the critical exponents ν and η, at least at two-loop order, for a layered parallel plate geometry separated by a distance L, with periodic as well as antiperiodic boundary conditions on the plates. We utilize massive and massless fields in order to extract the exponents in independent ultraviolet and infrared scaling analysis, respectively, which are required in a complete description of the scaling regions for finite size systems. We prove that fixed points and other critical amounts either in the ultraviolet or in the infrared regime dependent on the plates boundary condition are a general feature of normalization conditions. We introduce a new description of typical crossover regimes occurring in finite size systems. Avoiding these crossovers, the three regions of finite size scaling present for each of these boundary conditions are shown to be indistinguishable in the results of the exponents in periodic and antiperiodic conditions, which coincide with those from the (bulk) infinite system.
Emergence of the four layer dynamical regime in turbulent pipe flow
Authors: Klewicki J. , Chin C. , Blackburn H. M. , Ooi A. , Marusic I.
Published: April 2012

Direct numerical simulations of fully developed turbulent pipe flow that span the Reynolds number range 90 ≲ δ+ ≲ 1000 are used to investigate the evolution of the mean momentum field in and beyond the transitional regime. It is estimated that the four layer regime for pipe flow is nominally established for δ+ ⩾ 180, which is also close to the value found for channel flow. Primary attention is paid to the magnitude ordering and scaling behaviors of the terms in the mean momentum equation. Once the ordering underlying the existence of four distinct balance layers is attained, this ordering is sustained for all subsequent increases in Reynolds number. Comparisons indicate that pipe flow develops toward the four layer regime in a manner similar to that for channel flow, but distinct from that for the boundary layer. Small but discernible differences are observed in the mean momentum field development in pipes and channels. These are tentatively attributed to variations in the manner by which the outer region mean vorticity field develops in these two flows.
Compact, low power radio frequency cavity for femtosecond electron microscopy
Authors: Lassise A. , Mutsaers P. H. A. , Luiten O. J.
Published: April 2012

Reported here is the design, construction, and characterization of a small, power efficient, tunable dielectric filled cavity for the creation of femtosecond electron bunches in an existing electron microscope without the mandatory use of femtosecond lasers. A 3 GHz pillbox cavity operating in the TM110 mode was specially designed for chopping the beam of a 30 keV scanning electron microscope. The dielectric material used is ZrTiO4, chosen for the high relative permittivity (ɛr = 37 at 10 GHz) and low loss tangent (tan δ = 2 × 10−4). This allows the cavity radius to be reduced by a factor of six, while the power consumption is reduced by an order of magnitude compared to a vacuum pillbox cavity. These features make this cavity ideal as a module for existing electron microscopes, and an alternative to femtosecond laser systems integrated with electron microscopes.
Upgrade of the MIT Linear Electrostatic Ion Accelerator (LEIA) for nuclear diagnostics development for Omega, Z and the NIF
Authors: Sinenian N. , Manuel M. J.-E. , Zylstra A. B. , Rosenberg M. , Waugh C. J. , Rinderknecht H. G. , Casey D. T. , Sio H. , Ruszczynski J. K. , Zhou L. , Johnson M. Gatu , Frenje J. A. , Séguin F. H. , Li C. K. , Petrasso R. D. , Ruiz C. L. , Leeper R. J.
Published: April 2012

The MIT Linear Electrostatic Ion Accelerator (LEIA) generates DD and D3He fusion products for the development of nuclear diagnostics for Omega, Z, and the National Ignition Facility (NIF). Significant improvements to the system in recent years are presented. Fusion reaction rates, as high as 107 s−1 and 106 s−1 for DD and D3He, respectively, are now well regulated with a new ion source and electronic gas control system. Charged fusion products are more accurately characterized, which allows for better calibration of existing nuclear diagnostics. In addition, in situ measurements of the on-target beam profile, made with a CCD camera, are used to determine the metrology of the fusion-product source for particle-counting applications. Finally, neutron diagnostics development has been facilitated by detailed Monte Carlo N-Particle Transport (MCNP) modeling of neutrons in the accelerator target chamber, which is used to correct for scattering within the system. These recent improvements have resulted in a versatile platform, which continues to support the existing nuclear diagnostics while simultaneously facilitating the development of new diagnostics in aid of the National Ignition Campaign at the National Ignition Facility.
A new method for investigating infrared spectra of protonated benzene (C6H7+) and cyclohexadienyl radical (c-C6H7) using para-hydrogen
Authors: Bahou Mohammed , Wu Yu-Jong , Lee Yuan-Pern
Published: April 2012

We use protonated benzene (C6H7+) and cyclohexadienyl radical (c-C6H7) to demonstrate a new method that has some advantages over other methods currently used. C6H7+ and c-C6H7 were produced on electron bombardment of a mixture of benzene (C6H6) and para-hydrogen during deposition onto a target at 3.2 K. Infrared (IR) absorption lines of C6H7+ decreased in intensity when the matrix was irradiated at 365 nm or maintained in the dark for an extended period, whereas those of c-C6H7 increased in intensity. Observed vibrational wavenumbers, relative IR intensities, and deuterium isotopic shifts agree with those predicted theoretically. This method, providing a wide spectral coverage with narrow lines and accurate relative IR intensities, can be applied to larger protonated polyaromatic hydrocarbons and their neutral species which are difficult to study with other methods.
18/20 T high magnetic field scanning tunneling microscope with fully low voltage operability, high current resolution, and large scale searching ability
Authors: Li Quanfeng , Wang Qi , Hou Yubin , Lu Qingyou
Published: April 2012

We present a home-built 18/20 T high magnetic field scanning tunneling microscope (STM) featuring fully low voltage (lower than ±15 V) operability in low temperatures, large scale searching ability, and 20 fA high current resolution (measured by using a 100 GOhm dummy resistor to replace the tip-sample junction) with a bandwidth of 3.03 kHz. To accomplish low voltage operation which is important in achieving high precision, low noise, and low interference with the strong magnetic field, the coarse approach is implemented with an inertial slider driven by the lateral bending of a piezoelectric scanner tube (PST) whose inner electrode is axially split into two for enhanced bending per volt. The PST can also drive the same sliding piece to inertial slide in the other bending direction (along the sample surface) of the PST, which realizes the large area searching ability. The STM head is housed in a three segment tubular chamber, which is detachable near the STM head for the convenience of sample and tip changes. Atomic resolution images of a graphite sample taken under 17.6 T and 18.0001 T are presented to show its performance.
Optically optimal wavelength-scale patterned ITO/ZnO composite coatings for thin film solar cells
Authors: Moreau Antoine , Smaali Rafik , Centeno Emmanuel , Seassal Christian
Published: April 2012

A methodology is proposed for finding structures that are, optically speaking, locally optimal: a physical analysis of much simpler structures is used to constrain the optimization process. The obtained designs are based on a flat amorphous silicon layer (to minimize recombination) with a patterned anti-reflective coating made of ITO or ZnO, or a composite ITO/ZnO coating. These latter structures are realistic and present good performances despite very thin active layers.
Density functional theory with fractional orbital occupations
Authors: Chai Jeng-Da
Published: April 2012

In contrast to the original Kohn-Sham (KS) formalism, we propose a density functional theory (DFT) with fractional orbital occupations for the study of ground states of many-electron systems, wherein strong static correlation is shown to be described. Even at the simplest level represented by the local density approximation (LDA), our resulting DFT-LDA is shown to improve upon KS-LDA for multi-reference systems, such as dissociation of H2 and N2, and twisted ethylene, while performing similar to KS-LDA for single-reference systems, such as reaction energies and equilibrium geometries. Because of its computational efficiency (similar to KS-LDA), this DFT-LDA is applied to the study of the singlet-triplet energy gaps (ST gaps) of acenes, which are “challenging problems” for conventional electronic structure methods due to the presence of strong static correlation effects. Our calculated ST gaps are in good agreement with the existing experimental and high-level ab initio data. The ST gaps are shown to decrease monotonically with the increase of chain length, and become vanishingly small (within 0.1 kcal/mol) in the limit of an infinitely large polyacene. In addition, based on our calculated active orbital occupation numbers, the ground states for large acenes are shown to be polyradical singlets.
Flexoelectric phase shifter for spin waves
Authors: Liu Tianyu , Vignale G.
Published: April 2012

A controlled phase shifter for spin waves is an essential component of spin-wave logic devices. Theoretical calculations indicate that electrical control of the spin-wave phase can be realized in a simple ferromagnet that lacks long-ranged electric order by the interaction between an electric field and the spatial gradient of the magnetization—known as a flexoelectric interaction. Making use of a previous estimate of the strength of the flexoelectric coupling in ferromagnetic insulator Y3Fe5O12 (yttrium iron garnet) we find that a change in wave vector of the order of 1% can be achieved with an electric field of 106 V/m.
Control of absorption with hyperbolic metamaterials
Authors: Tumkur T. U. , Gu Lei , Kitur J. K. , Narimanov E. E. , Noginov M. A.
Published: April 2012

We show that absorption of thin dye-doped polymeric films can be tuned and enhanced (nearly threefold) by metallic and lamellar metal-dielectric hyperbolic metamaterial substrates. The effect can be controlled by a combination of the substrate’s geometry and composition. As the enhancement of absorption is sustained over large range of incidence angles, the demonstrated phenomenon can lead to a variety of important applications, including solar cell technology.
Photoelectron spectroscopy of the molecular anions, ZrO−, HfO−, HfHO−, and HfO2H−
Authors: Li Xiang , Zheng Weijun , Buonaugurio Angela , Buytendyk Allyson , Bowen Kit , Balasubramanian Krishnan
Published: April 2012

Negative ion photoelectron spectra of ZrO−, HfO−, HfHO−, and HfO2H− are reported. Even though zirconium- and hafnium-containing molecules typically exhibit similar chemistries, the negative ion photoelectron spectral profiles of ZrO− and HfO− are dramatically different from one another. By comparing these data with relevant theoretical and experimental studies, as well as by using insights drawn from atomic spectra, spin-orbit interactions, and relativistic effects, the photodetachment transitions in the spectra of ZrO− and HfO− were assigned. As a result, the electron affinities of ZrO and HfO were determined to be 1.26 ± 0.05 eV and 0.60 ± 0.05 eV, respectively. The anion photoelectron spectra of HfHO− and HfO2H− are similar to one another and their structural connectivities are likely to be H–Hf–O− and O–Hf–OH−, respectively. The electron affinities of HfHO and HfO2H are 1.70 ± 0.05 eV and 1.73 ± 0.05 eV, respectively.
Metal–semiconductor transition in ultrathin cobalt-phthalocyanine films grown on SrTiO3 single crystal substrates
Authors: Samanta S. , Kumar Arvind , Singh A. , Debnath A. K. , Veerender P. , Basu S. , Prasad R. , Aswal D. K. , Gupta S. K.
Published: April 2012

We have investigated the low temperature charge transport properties of ultrathin cobalt-phthalocyanine films grown on (100) SrTiO3 single crystal substrates. The temperature dependence of resistivity shows an anomalous behavior, i.e., a transition from semiconducting to metallic behavior at around 110 K. We demonstrated that metallic behavior in these films is triggered by compressive strains of the SrTiO3 substrate due to its cubic to tetragonal structural phase transition at 110 K.
Two-dimensional electron gas mobility limited by barrier and quantum well thickness fluctuations scattering in AlxGa1−xN/GaN multi-quantum wells
Authors: Liu Guipeng , Wu Ju , Lu Yanwu , Zhao Guijuan , Gu Chengyan , Liu Changbo , Sang Ling , Yang Shaoyan , Liu Xianglin , Zhu Qinsheng , Wang Zhanguo
Published: April 2012

We calculate the electron mobility limited by the AlxGa1−xN barrier and the GaN well thickness fluctuations scattering of the two-dimensional electron gas (2DEG) at AlxGa1−xN/GaN multi-quantum wells (MQWs) with a triangle potential well. For this potential well, the ground subband energy is governed by the spontaneous and piezoelectric polarization fields and the fields are determined by the barrier and well thicknesses in undoped AlxGa1−xN/GaN MQWs. Thus, the thickness fluctuations of AlxGa1−xN barrier and GaN well will cause a local fluctuation of the ground subband energy, which will reduce the 2DEG mobility.
Co/Au multilayers with graded magnetic anisotropy for magnetic field sensing
Authors: Matczak M. , Kuświk P. , Szymański B. , Urbaniak M. , Schmidt M. , Aleksiejew J. , Stobiecki F. , Ehresmann A.
Published: April 2012

A concept of a magnetoresistive sensor for magnetic fields based on a Au/Co-wedge/Au/Co/Au multilayer is proposed. The wedged Co layer is characterized by a laterally changing coercivity resulting from a gradient of perpendicular magnetic anisotropy. Its magnetization reversal in a perpendicular magnetic field takes place by movement of a single domain wall in the direction parallel to the anisotropy gradient. The magnetization reversal of the multilayer has been investigated by magnetooptical and magnetoresistive measurements. The resistance of the proposed film system correlates well with the position of the domain wall and thus it can be used to sense magnetic fields.
Silicon carbide coated silicon nanowires as robust electrode material for aqueous micro-supercapacitor
Authors: Alper John P. , Vincent Maxime , Carraro Carlo , Maboudian Roya
Published: April 2012

The development of passivated silicon nanowire (SiNW) based micro-supercapacitor electrodes for on-chip applications using an environmentally benign aqueous electrolyte is reported. The SiNWs, produced by low-temperature (50 °C) electrochemical etching, corrode during charge/discharge cycling in the aqueous environment, but upon coating with a silicon carbide passivation layer, the corrosion is mitigated. The as-formed materials are in electrical contact with the substrate, requiring no additional current collector. The passivated NWs achieve capacitance values up to ∼1.7 mF/cm2 projected area (comparable to state-of-the art carbon based micro-supercapacitor electrodes), exhibit robust cycling stability, and maintain capacitive behavior over a wide range of charge/discharge rates.