bluuebunny/crossref_metadata_2025 huggingface dataset:
The (Paleo)Geography of Evolution: Making Sense of Changing Biology and Changing Continents
Authors: Meert Joseph G.
Published: April 2012

During the voyage of the H.M.S. Beagle, Charles Darwin quickly realized that geographic isolation led to significant changes in the adaptation of local flora and fauna (Darwin 1859). Genetic isolation is one of the well-known mechanisms by which adaptation (allopatric speciation) can occur (Palumbi, Annu Rev Ecol Syst 25:547–72, 1994; Ricklefs, J Avian Biol 33:207–11, 2002; Burns et al., Evolution 56:1240–52, 2002; Hendry et al., Science 290:516–8, 2009). Evolutionary changes can also occur when landmasses converge or are “bridged.” An important and relatively recent (Pliocene Epoch) example known as the “Great American Biotic Interchange” allowed for the migration of previously isolated species into new ecological niches between North and South America (Webb 1985, Ann Mo Bot Gard 93:245–57, 2006; Kirby and MacFadden, Palaeogeogr Palaeoclimatol Palaeoecol 228:193–202, 2005). Geographic isolation (vicariance) or geographic merging (geodispersal) can occur for a variety of reasons (sea level rise, splitting of continents, mountain building). In addition, the growth of a large supercontinent (or breakup) may change the climatic zonation on the globe and form a different type of barrier for species migration. This short review paper focuses on changing paleogeography throughout the Phanerozoic and the close ties between paleogeography and the evolutionary history of life on Earth.
Fetal MR in the evaluation of pulmonary and digestive system pathology
Authors: Martin César , Darnell Anna , Escofet Conxita , Duran Carmina , Pérez Víctor
Published: April 2012

Background

Prenatal awareness of an anomaly ensures better management of the pregnant patient, enables medical teams and parents to prepare for the delivery, and is very useful for making decisions about postnatal treatment. Congenital malformations of the thorax, abdomen, and gastrointestinal tract are common. As various organs can be affected, accurate location and morphological characterization are important for accurate diagnosis.

Methods

Magnetic resonance imaging (MRI) enables excellent discrimination among tissues, making it a useful adjunct to ultrasonography (US) in the study of fetal morphology and pathology.

Results

MRI is most useful when US has detected or suspected anomalies, and more anomalies are detected when MRI and US findings are assessed together.

Conclusion

We describe the normal appearance of fetal thoracic, abdominal, and gastrointestinal structures on MRI, and we discuss the most common anomalies involving these structures and the role of MRI in their study.

Teaching Points

• To learn about the normal anatomy of the fetal chest, abdomen, and GI tract on MRI.

• To recognize the MR appearance of congenital anomalies of the lungs and the digestive system.

• To understand the value of MRI when compared to US in assessing fetal anomalies.
Orbital lymphoma: imaging features and differential diagnosis
Authors: Priego Gema , Majos Carles , Climent Fina , Muntane Amadeo
Published: April 2012

Purpose

Patterns of orbital lymphoma at diagnosis and follow-up are described. We also discuss differential diagnosis of orbital masses.

Materials and methods

This pictorial review contains 19 cases of orbital lymphoma before and after treatment. Superior-lateral quadrant and extra-conal location were observed predominantly. Effective response after treatment was presented on follow-up imaging, although few local relapses were found. Further follow-up showed no changes of residual images.

Discussion

Location of orbital masses can help in the differential diagnosis. Moreover, imaging features of lymphoma at diagnosis can be useful in planning surgical biopsy. Pattern of follow-up described may be relevant on monitoring imaging.

Teaching points

• Orbital lymphoma involves mainly superior-lateral quadrant and the orbital structures inside.

• Location of retrobulbar mass-like lesions are useful information in the differential diagnosis.

• Satisfactory response is detected after treatment, however relapse is noted, so follow-up is needed.
Radiological appearances of gynaecological emergencies
Authors: Roche Oran , Chavan Nikita , Aquilina Joseph , Rockall Andrea
Published: April 2012

Background

The role of various gynaecological imaging modalities is vital in aiding clinicians to diagnose acute gynaecological disease, and can help to direct medical and surgical treatment where appropriate. It is important to interpret the imaging findings in the context of the clinical signs and patient's pregnancy status.

Methods

Ultrasound and Doppler are readily available in the emergency department, and demonstrate features of haemorrhagic follicular cysts, ovarian cyst rupture, endometriotic cysts and pyosalpinx. Adnexal torsion may also be identified using ultrasound and Doppler, although the diagnosis cannot be safely excluded based on imaging alone. Computed tomography (CT) is not routinely employed in diagnosing acute gynaecological complications. However due to similar symptoms and signs with gastrointestinal and urinary tract pathologies, it is frequently used as the initial imaging modality and recognition of features of gynaecological complications on CT is important.

Results

Although MRI is not frequently used in the emergency setting, it is an important modality in characterising features that are unclear on ultrasound and CT.

Conclusion

MRI is particularly helpful in identifying the site of origin of large pelvic masses, such as haemorrhagic uterine fibroid degeneration and fibroid prolapse or torsion. In this article, we review the imaging appearances of gynaecological emergencies in non-pregnant patients.

Teaching points

• Ultrasonography is easily accessible and can identify life-threatening gynaecological complications.

• Tomography scanners and computed radiography are not routinely used but are important to recognise key features.

• MRI is used for the characterisation of acute gynaecological complications.

• Recognition of the overlap in symptoms between gastrointestinal and gynaecological conditions is essential.
Anterior cingulate morphology in people at genetic high-risk of schizophrenia
Authors: Meredith S.M. , Whyler N.C.A. , Stanfield A.C. , Chakirova G. , Moorhead T.W.J. , Job D.E. , Giles S. , McIntosh A.M. , Johnstone E.C. , Lawrie S.M.
Published: April 2012

Background

Morphological abnormalities of the anterior cingulate (AC) occur in patients with schizophrenia and in symptomatic high-risk individuals, and may be predictive of subsequent psychosis. We investigated AC sulcal morphology in the Edinburgh High Risk Study cohort to see if such abnormalities are evident and predict psychosis in patients’ relatives. We also investigated the association of the cingulate sulcus (CS) and paracingulate sulcus (PCS) variants with intelligence quotient (IQ).

Patients and methods

We compared cingulate and paracingulate sulcal anatomy, using reliable standardised measurements, blind to group membership, in those at high genetic risk (n = 146), first episode patients (n = 34) and healthy controls (n = 36); and compared high-risk subjects who did (n = 17) or did not develop schizophrenia.

Results

Interruptions of the cingulate sulcus were more common in high-risk individuals and in those with schizophrenia, in both hemispheres, compared to controls. When separated by gender, these results were only present in males in the left hemisphere and only in females in the right hemisphere. A well-formed paracingulate sulcus was less common in high-risk participants and patients with schizophrenia, compared to controls; but this association was only present in males. These morphological variants of the paracingulate sulcus and the continuous cingulate sulcus were also associated with the higher IQ in male high-risk individuals.

Conclusions

An interrupted cingulate sulcus pattern in both males and females and paracingulate morphology in males are associated with increased genetic risk of schizophrenia. Associations between cingulate and paracingulate morphology and premorbid IQ scores provide evidence that intellectual ability could be related to particular cytoarchitectural brain regions. Given that these sulci develop in early fetal life, such findings presumably reflect early neurodevelopmental abnormalities of genetic origin, although environmental effects and interactions cannot be ruled out.
A reporter system for translational readthrough of stop codons in human cells
Authors: Halvey Patrick J. , Liebler Daniel C. , Slebos Robbert J.C.
Published: April 2012

Agents to induce readthrough of premature termination codons (PTCs) are useful research tools and potential therapeutics. Reporters used to detect PTC readthrough are gene‐specific and thus are not suited to for general assessment of readthrough activity or in cases where PTC‐inactivated genes are unknown. Here we describe a GFP‐based reporter construct pMHG‐W57∗ which is capable of detecting dose‐dependent drug‐induced PTC readthrough both by fluorescence microscopy and flow cytometry. pMHG‐W57∗ may be used as a general indicator of PTC readthrough in living cells and obviates the need for gene‐specific recoding sequences in reporter constructs.
Identification of recurrence‐related microRNAs in hepatocellular carcinoma following liver transplantation
Authors: Han Zhong-Bo , Zhong Lin , Teng Mu-Jian , Fan Jun-Wei , Tang Hua-Mei , Wu Jun-Yi , Chen Hong-Yuan , Wang Zhao-Wen , Qiu Guo-Qiang , Peng Zhi-Hai
Published: April 2012

Tumor recurrence‐related microRNAs (miRNAs) in hepatocellular carcinoma (HCC) following orthotopic liver transplantation (OLT) are not clear yet. This study was designed to determine whether altered miRNA expression is associated with HCC recurrence and prognosis following OLT. 18 miRNAs, including 6 up‐regulated and 12 down‐regulated miRNAs were identified by microarray in primary HCC samples of patients who had developed HCC recurrence (n = 5) compared to those with non‐recurrence (n = 5) following OLT by using p < 0.05 as cutoff value. The six most significantly altered miRNAs (fold change ≥ 2: miR‐19a, miR‐886‐5p, miR‐126, miR‐223, miR‐24 and miR‐147) were further confirmed by qRT‐PCR in the remaining 105 HCC samples. In receiver‐operating characteristic curve analysis, this six miRNAs were of high sensitivity and specificity in predicting HCC recurrence. Using Cox regression and risk score analysis, we built a six‐miRNA signature based on their qRT‐PCR readings for the prediction of outcome of HCC following OLT. Kaplan–Meier and Cox proportional regression revealed this six‐miRNA signature was a significant independent predictor of overall survival (log‐rank p = 0.020) and recurrence‐free survival (log‐rank p < 0.001). Finally, the data were further reconfirmed in an independent cohort of 50 patients from another transplant center. In addition, bioinformatics Gene Ontology and pathway analysis were also performed to better understand the critical roles of these miRNAs in HCC recurrence. Our study, in addition to suggesting a different miRNA expression pattern between HCC samples of patients with recurrence and those with non‐recurrence, proposes that this six‐miRNA signature may serve as biomarker for prognosis of HCC patients following OLT.
A logit model of retail investors' individual trading decisions and their relations to insider trades
Authors: Stotz Olaf , Georgi Dominik
Published: April 2012

Among the various external information sources that influence individual investors' trading decisions, no research has considered the important influence of insiders' transactions. Retail investors might copy the behavior demonstrated by insiders' trading; therefore, this study establishes an approach to estimate the buying probability for a certain stock by a certain investor at a certain point in time and analyzes whether insider trade reports influence this probability. Using a sample of more than 270,000 retail trades in Germany between 2008 and 2009, along with more than 3000 insider trades in the same period, we find evidence of copying of insiders' trades by retail investors. The basic mimicry hypothesis holds, even when we consider an information event hypothesis and an insider attention effect hypothesis as alternative explanations. A robustness test also supports the findings.
Bottom-trapped currents as statistical equilibrium states above topographic anomalies
Authors: Venaille A.
Published: April 2012

Oceanic geostrophic turbulence is mostly forced at the surface, yet strong bottom-trapped flows are commonly observed along topographic anomalies. Here we consider the case of a freely evolving, initially surface-intensified velocity field above a topographic bump, and show that the self-organization into a bottom-trapped current can result from its turbulent dynamics. Using equilibrium statistical mechanics, we explain this phenomenon as the most probable outcome of turbulent stirring. We compute explicitly a class of solutions characterized by a linear relation between potential vorticity and streamfunction, and predict when the bottom intensification is expected. Using direct numerical simulations, we provide an illustration of this phenomenon that agrees qualitatively with theory, although the ergodicity hypothesis is not strictly fulfilled.
Release of a viscous power-law fluid over an inviscid ocean
Authors: Pegler Samuel S. , Lister John R. , Worster M. Grae
Published: April 2012

We consider the two- and three-dimensional spreading of a finite volume of viscous power-law fluid released over a denser inviscid fluid and subject to gravitational and capillary forces. In the case of gravity-driven spreading, with a power-law fluid having strain rate proportional to stress to the power $n$, there are similarity solutions with the extent of the current being proportional to ${t}^{1/ n} $ in the two-dimensional case and ${t}^{1/ 2n} $ in the three-dimensional case. Perturbations from these asymptotic states are shown to retain their initial shape but to decay relatively as ${t}^{\ensuremath{-} 1} $ in the two-dimensional case and ${t}^{\ensuremath{-} 3/ (n+ 3)} $ in the three-dimensional case. The former is independent of $n$, whereas the latter gives a slower rate of relative decay for fluids that are more shear-thinning. In cases where the layer is subject to a constraining surface tension, we determine the evolution of the layer towards a static state of uniform thickness in which the gravitational and capillary forces balance. The asymptotic form of this convergence is shown to depend strongly on $n$, with rapid finite-time algebraic decay in shear-thickening cases, large-time exponential decay in the Newtonian case and slow large-time algebraic decay in shear-thinning cases.
The spatial genetic differentiation of the legume pod borer,Maruca vitrataF. (Lepidoptera: Crambidae) populations in West Africa
Authors: Agunbiade T.A. , Coates B.S. , Kim K.S. , Forgacs D. , Margam V.M. , Murdock L.L. , Ba M.N. , Binso-Dabire C.L. , Baoua I. , Ishiyaku M.F. , Tamò M. , Pittendrigh B.R.
Published: April 2012

The legume pod borer,Maruca vitrata, is an endemic insect pest that causes significant yield loss to the cowpea crop in West Africa. The application of population genetic tools is important in the management of insect pests but such data onM. vitratais lacking. We applied a set of six microsatellite markers to assess the population structure ofM. vitratacollected at five sites from Burkina Faso, Niger and Nigeria. Observed polymorphisms ranged from one (marker 3393) to eight (marker 32008) alleles per locus. Observed and expected heterozygosities ranged from 0.0 to 0.8 and 0.0 to 0.6, respectively. Three of the loci in samples from Nigeria and Burkina Faso deviated significantly from Hardy-Weinberg Equilibrium (HWE), whereas no loci deviated significantly in samples from Niger. Analysis of molecular variance (AMOVA) indicated that 67.3% level of the genetic variation was within individuals compared to 17.3% among populations. A global estimate ofFST=0.1 (ENA correctedFST=0.1) was significant (P⩽0.05) and corroborated by pairwiseFSTvalues that were significant among all possible comparisons. A significant correlation was predicted between genetic divergence and geographic distance between subpopulations (R2=0.6,P=0.04), and cluster analysis by the program STRUCTURE predicted that co-ancestry of genotypes were indicative of three distinct populations. The spatial genetic variance amongM. vitratain West Africa may be due to limited gene flow, south-north seasonal movement pattern or other reproductive barriers. This information is important for the cultural, chemical and biological control strategies for managingM. vitrata.
Composition of cuticular lipids in the pteromalid wasp Lariophagus distinguendus is host dependent
Authors: Kühbandner S. , Hacker K. , Niedermayer S. , Steidle J.L.M. , Ruther J.
Published: April 2012

The insect cuticle is covered by a thin layer of hydrocarbons not only preventing desiccation but also playing an important role in the sexual communication of several species. In the pteromalid wasp Lariophagus distinguendus, a parasitoid of grain infesting beetles, female cuticular hydrocarbons (CHCs) elicit male courtship behaviour. We analyzed the CHC profiles of male and female L. distinguendus wasps reared on different beetle hosts by coupled gas chromatography- mass spectrometry (GC-MS). Statistical analysis of the data revealed significant differences between strains reared on different hosts, while spatially isolated strains reared on the same host produced similar profiles. CHC profiles of parasitoids reared on Stegobium paniceum were statistically distinguishable from those of wasps reared on all other hosts. A host shift from Sitophilus granarius to S. paniceum resulted in distinguishable CHC profiles of L. distinguendus females after only one generation. Considering the role of CHCs as contact sex pheromones, our data suggest that host shifts in parasitic wasps might lead to reproductive isolation of host races due to the modification of the cuticular semiochemistry.
Kefir grains as a starter for whey fermentation at different temperatures: chemical and microbiological characterisation
Authors: Londero Alejandra , Hamet María F. , De Antoni Graciela L. , Garrote Graciela L. , Abraham Analía G.
Published: April 2012

We report here a comparative analysis of the growth, acidification capacity, and chemical and microbiologic composition between kefir grains after 20 subcultures in whey at 20, 30, and 37°C and the original kefir grains coming from milk along with a determination of the microbiological composition of the fermented whey as compared with that of traditional fermented milk.

When fermentation was carried out repeatedly at 30 or 37°C, kefir grains changed their kefir-like appearance, exhibited reduced growth rates, had a lower diversity of yeasts and water content, and a higher protein-to-polysaccharide ratio compared with the original kefir grains. In contrast, at 20°C kefir grains could remain in whey for prolonged periods without altering their acidification capacity, growth rate, macroscopic appearance or chemical and microbiologic composition—with the only difference being a reduction in certain yeast populations after 20 subcultures in whey. At this incubation temperature, the presence ofLactobacillus kefiranofaciens, Lb. kefir, Lb. parakefir, Lactococcus lactis, Kluyveromyces marxianus, Saccharomyces unisporus, andSac. cerevisiaewas detected in kefir grains and in fermented whey by denaturing-gradient-gel electrophoresis (DGGE). In whey fermented at 20°C the number of lactic-acid bacteria (LAB) was significantly lower (P<0·05) and the number of yeast significantly higher (P<0·05) than in fermented milk. Since the DGGE profiles were similar for both products, at this temperature the microbiologic composition of fermented whey is similar to that of fermented milk. We therefore suggest a temperature of 20°C to preserve kefir grains as whey-fermentation starters.
The Log-Linear Return Approximation, Bubbles, and Predictability
Authors: Engsted Tom , Pedersen Thomas Q. , Tanggaard Carsten
Published: April 2012

We study in detail the log-linear return approximation introduced by Campbell and Shiller (1988a). First, we derive an upper bound for the mean approximation error, given stationarity of the log dividend-price ratio. Next, we simulate various rational bubbles that have explosive conditional expectation, and we investigate the magnitude of the approximation error in those cases. We find that, surprisingly, the Campbell-Shiller approximation is very accurate even in the presence of large explosive bubbles. Only in very large samples do we find evidence that bubbles generate large approximation errors. Finally, we show that a bubble model in which expected returns are constant can explain the predictability of stock returns from the dividend-price ratio that many previous studies have documented.
An analytical study on the existence of solitary structure at M = Mc
Authors: DAS ANIMESH , BANDYOPADHYAY ANUP , DAS K. P.
Published: April 2012

A general theory for the existence of solitary structure at M = Mc has been discussed, where Mc is the lower bound of the Mach number M, i.e., solitary structures start to exist for M > Mc. Three important results have been proved to confirm the existence of solitary structure at M = Mc. If V(φ)(≡ V(M,φ)) denotes the Sagdeev potential with φ being the perturbed field or perturbed dependent variable associated with a specific problem, V(M, φ) is well defined as a real number for all M ∈ ℳ and φ ∈ Φ0, and V(M, 0) = V′(M, 0) = V″(Mc, 0) = 0, V‴(Mc, 0) < 0 (V‴(Mc, 0) > 0), ∂ V/∂ M < 0 for all M (∈ ℳ) > 0 and φ (∈ Φ0) > 0 (φ (∈ Φ0) < 0), where ‘′ ≡ ∂/∂φ’, the main analytical results for the existence of solitary wave or double layer solution of the energy integral at M = Mc are as follows. Result 1: If there exists at least one value M0 of M such that the system supports positive (negative) potential solitary waves for all Mc < M < M0, then there exists either a positive (negative) potential solitary wave or a positive (negative) potential double layer at M = Mc. Result 2: If the system supports only negative (positive) potential solitary waves for M > Mc, then there does not exist positive (negative) potential solitary wave at M = Mc. Result 3: It is not possible to have coexistence of both positive and negative potential solitary structures at M = Mc. Apart from the conditions of Result 1, the double layer solution at M = Mc is possible only when there exists a double layer solution in any right neighborhood of Mc. Finally, these analytical results have been applied to a specific problem on dust acoustic (DA) waves in non-thermal plasma in search of new results.
The real presence
Authors: BABER H. E.
Published: April 2012

The doctrine that Christ is really present in the Eucharist appears to entail that Christ's body is not only multiply located but present in different ways at different locations. Moreover, the doctrine poses an even more difficult meta-question: what makes a theological explanation of the Eucharist a ‘real presence’ account? Aquinas's defence of transubstantiation, perhaps the paradigmatic account, invokes Aristotelian metaphysics and the machinery of Scholastic philosophy. My aim is not to produce a ‘rational reconstruction’ of his analysis but rather to suggest a metaphysically innocent alternative that will ‘save the phenomena’ of religious belief and practice.
A conceptualist argument for a spiritual substantial soul
Authors: MORELAND J. P.
Published: April 2012

I advance a type of conceptualist argument for substance dualism – minimally, the view that we are spiritual substances that have bodies – based on the understandability of what it would be for something to be a spirit, e.g. what it would be for God to be a spirit. After presenting the argument formally, I clarify and defend its various premises with a special focus on what I take to be the most controversial one, namely, if thinking (i.e. conscious) matter is metaphysically possible, it is not the case that we have a distinct positive concept of God's being a divine spirit.
Lower and upper bounds for the Lyapunov exponents of twisting dynamics: a relationship between the exponents and the angle of Oseledets’ splitting
Authors: ARNAUD M.-C.
Published: April 2012

We consider locally minimizing measures for conservative twist maps of the $d$-dimensional annulus and for Tonelli Hamiltonian flows defined on a cotangent bundle $T^*M$. For weakly hyperbolic measures of such type (i.e. measures with no zero Lyapunov exponents), we prove that the mean distance/angle between the stable and unstable Oseledets bundles gives an upper bound on the sum of the positive Lyapunov exponents and a lower bound on the smallest positive Lyapunov exponent. We also prove some more precise results.
Nonadditive measure-theoretic pressure and applications to dimensions of an ergodic measure
Authors: CAO YONGLUO , HU HUYI , ZHAO YUN
Published: April 2012

Without any additional conditions on subadditive potentials, this paper defines subadditive measure-theoretic pressure, and shows that the subadditive measure-theoretic pressure for ergodic measures can be described in terms of measure-theoretic entropy and a constant associated with the ergodic measure. Based on the definition of topological pressure on non-compact sets, we give another equivalent definition of subadditive measure-theoretic pressure, and obtain an inverse variational principle. This paper also studies the superadditive measure-theoretic pressure which has similar formalism to the subadditive measure-theoretic pressure. As an application of the main results, we prove that an average conformal repeller admits an ergodic measure of maximal Hausdorff dimension. Furthermore, for each ergodic measure supported on an average conformal repeller, we construct a set whose dimension is equal to the dimension of the measure.
Outdoor adventure and successful ageing
Authors: BOYES MIKE
Published: April 2012

This article explores how outdoor adventure activities in a New Zealand community-based programme are experienced and understood as successful ageing strategies. Outdoor adventures are seen as positive leisure experiences that include challenging physical activity, social engagement and the natural environment. Using a sequential exploratory mixed-methods design, a combination of seven interviews and a survey (N=80) were conducted with a Third Age adventures group. The research outcomes confirmed the attraction of adventure for this cohort. Risk engagement and uncertainty were perceived as less important in favour of emotional, social and environmental engagement through fun, excitement and pleasure. The natural environment was considered integral and defining of the experience with the participants demonstrating a strong environmental ethos. Opportunities for building social capital were plentiful and well illustrated. The benefits of engagement for health, wellbeing and successful ageing are identified through the physical, social and psychological domains. The research supports adventure participation as a successful ageing strategy that is relatively low cost, community based, has many preventative health benefits, builds communities and embraces the environment.
Cyclotron resonance effects on electron acceleration by two lasers of different wavelengths
Authors: Gupta D.N. , Singh K.P. , Suk H.
Published: April 2012

Cyclotron resonance effects on electron acceleration by two lasers of different wavelengths in the presence of a magnetic field have been investigated. Beating of two high-intensity lasers of different wavelengths, propagating in opposite direction to each other, can produce a high accelerating field gradient. An electron can be accelerated by such accelerating field to a sufficiently higher energy level. Additional energy gain has been observed due to the applied magnetic field. The magnetic field turns down the electrons to the acceleration region to extract more energy from the accelerating field produced by the beating of the lasers. At resonance, when the Larmor frequency is comparable to the laser frequency, this effect becomes more pronounced. Using some reasonable experimental parameters, we estimate the electron energy gain for this mechanism.
Betatron radiation damping in laser plasma acceleration
Authors: Deng Aihua , Nakajima Kazuhisa , Zhang Xiaomei , Lu Haiyang , Shen Baifei , Liu Jiansheng , Li Ruxin , Xu Zhizhan
Published: April 2012

We explore the feasibility of accelerating electron beams up to energies much beyond 1 TeV in a realistic scale and evolution of the beam qualities such as emittance and energy spread at the final beam energy on the order of 100 TeV, using the newly formulated coupled equations describing the beam dynamics and radiative damping of electrons. As an example, we present a design for a 100 TeV laser-plasma accelerator in the operating plasma density np = 1015 cm−3 and numerical solutions for evolution of the normalized emittance as well as their analytical solutions. We show that the betatron radiative damping causes very small normalized emittance that promises future applications for the high-energy frontier physics.
A novel line of sight control system for a robot vision tracking system, using vision feedback and motion-disturbance feedforward compensation
Authors: Park Jaehong , Hwang Wonsang , Kwon Hyunil , Kim Kwangsoo , Cho Dong-il “Dan”
Published: April 2012

This paper presents a novel line of sight control system for a robot vision tracking system, which uses a position feedforward controller to preposition a camera, and a vision feedback controller to compensate for the positioning error. Continuous target tracking is an important function for service robots, surveillance robots, and cooperating robot systems. However, it is difficult to track a specific target using only vision information, while a robot is in motion. This is especially true when a robot is moving fast or rotating fast. The proposed system controls the camera line of sight, using a feedforward controller based on estimated robot position and motion information. Specifically, the camera is rotated in the direction opposite to the motion of the robot. To implement the system, a disturbance compensator is developed to determine the current position of the robot, even when the robot wheels slip. The disturbance compensator is comprised of two extended Kalman filters (EKFs) and a slip detector. The inputs of the disturbance compensator are data from an accelerometer, a gyroscope, and two wheel-encoders. The vision feedback information, which is the targeting error, is used as the measurement update for the two EKFs. Using output of the disturbance compensator, an actuation module pans the camera to locate a target at the center of an image plane. This line of sight control methodology improves the recognition performance of the vision tracking system, by keeping a target image at the center of an image frame. The proposed system is implemented on a two-wheeled robot. Experiments are performed for various robot motion scenarios in dynamic situations to evaluate the tracking and recognition performance. Experimental results showed the proposed system achieves high tracking and recognition performances with a small targeting error.
High morbidity and mortality associated with an outbreak of influenza A(H3N2) in a psycho-geriatric facility
Authors: SAYERS G. , IGOE D. , CARR M. , COSGRAVE M. , DUFFY M. , CROWLEY B. , O'HERLIHY B.
Published: April 2012

In spring 2008, an influenza A subtype H3N2 outbreak occurred in a long stay psycho-geriatric ward and two wards in the intellectual disability services (IDS), part of a large psychiatric hospital. The attack rate in the index ward was 90% (18/20) for patients and 35% (7/20) for staff. It was 14% (1/7) and 17% (2/12) in the affected IDS wards for patients and 0% (0/20) and 4% (1/25) for staff. Many of the laboratory-confirmed cases did not have a fever >38 °C, a typical sign of influenza. Control measures included oseltamivir treatment for cases and prophylaxis for contacts, standard and droplet infection control precautions, active surveillance for early detection and isolation of potential cases. As a result, the outbreak did not spread throughout the hospital. Although the staff vaccination rate (10%) prior to the outbreak was low, we observed a much lower vaccine effectiveness rate in the patients (11%) than in the staff (100%) in the index ward. Vaccination of residents and staff of such facilities remains the key influenza prevention strategy.
Problems defining resiliency: Illustrations from the study of maltreated children
Authors: Kaufman Joan , Cook Alexandra , Arny Libby , Jones Brenda , Pittinsky Todd
Published: April 2012

In this article, operational definitions of resiliency used in previous studies are reviewed. Data from a sample of 56 maltreated school-age children are then explored to highlight how variations in the source, type, and number of assessments obtained affect the rates of children classified as resilient. Assessments were obtained in three domains: academic achievement, social competence, and clinical symptomatology. Two sources of information were used to assess each domain, and three different data integration procedures were used to calculate rates of resiliency in the maltreated cohort. It is concluded that the most appropriate definition of resiliency to be used in future investigations depends on the aims of the study. If the goal of the study is to assess overall functioning, there is an advantage to using more broad, multidimensional assessments. If, in contrast, the goal of the study is to determine why some high-risk children develop particular types of problems, to identify underlying etiological processes associated with different outcomes, there is an advantage to using narrower definitions.
How can the study of physiological reactivity contribute to our understanding of adversity and resilience processes in development?
Authors: Obradović Jelena
Published: April 2012

The focus of this article is to present current progress in understanding the interplay among adversity, physiological sensitivity to context, and adaptive functioning, with an emphasis on implications and future directions for resilience researchers. It includes a review of current literature that demonstrates (a) links between various levels of adversity exposure and variability in physiological reactivity, (b) how the interplay between children's physiological reactivity and different sources of risk and adversity relates to variability in adaptive functioning, and (c) various approaches for capturing a more dynamic nature of physiological reactivity and related processes. Throughout, important conceptual and empirical issues are highlighted.
Distinguishing differential susceptibility from diathesis–stress: Recommendations for evaluating interaction effects
Authors: Roisman Glenn I. , Newman Daniel A. , Fraley R. Chris , Haltigan John D. , Groh Ashley M. , Haydon Katherine C.
Published: April 2012

This report describes the state of the art in distinguishing data generated by differential susceptibility from diathesis–stress models. We discuss several limitations of existing practices for probing interaction effects and offer solutions that are designed to better differentiate differential susceptibility from diathesis–stress models and quantify their corresponding implications. In addition, we demonstrate the utility of these methods by revisiting published evidence suggesting that temperamental difficulty serves as a marker of enhanced susceptibility to early maternal caregiving across a range of outcome domains in the NICHD Study of Early Child Care and Youth Development. We find that, with the exception of mother reports of psychopathology, there is consistent evidence in the Study of Early Child Care and Youth Development that the predictive significance of early sensitivity is moderated by difficult temperament over time. However, differential susceptibility effects emerged primarily for teacher reports of academic skills, social competence, and symptomatology. In contrast, effects more consistent with the diathesis–stress model were obtained for mother reports of social skills and objective tests of academic skills. We conclude by discussing the value of the application of this work to the next wave of Gene × Environment studies focused on early caregiving experiences.
Gene × Environment interaction and resilience: Effects of child maltreatment and serotonin, corticotropin releasing hormone, dopamine, and oxytocin genes
Authors: Cicchetti Dante , Rogosch Fred A.
Published: April 2012

In this investigation, gene–environment interaction effects in predicting resilience in adaptive functioning among maltreated and nonmaltreated low-income children (N= 595) were examined. A multicomponent index of resilient functioning was derived and levels of resilient functioning were identified. Variants in four genes (serotonin transporter linked polymorphic region, corticotropin releasing hormone receptor 1, dopamine receptor D4–521C/T, and oxytocin receptor) were investigated. In a series of analyses of covariance, child maltreatment demonstrated a strong negative main effect on children's resilient functioning, whereas no main effects for any of the genotypes of the respective genes were found. However, gene–environment interactions involving genotypes of each of the respective genes and maltreatment status were obtained. For each respective gene, among children with a specific genotype, the relative advantage in resilient functioning of nonmaltreated compared to maltreated children was stronger than was the case for nonmaltreated and maltreated children with other genotypes of the respective gene. Across the four genes, a composite of the genotypes that more strongly differentiated resilient functioning between nonmaltreated and maltreated children provided further evidence of genetic variations influencing resilient functioning in nonmaltreated children, whereas genetic variation had a negligible effect on promoting resilience among maltreated children. Additional effects were observed for children based on the number of subtypes of maltreatment children experienced, as well as for abuse and neglect subgroups. Finally, maltreated and nonmaltreated children with high levels of resilience differed in their average number of differentiating genotypes. These results suggest that differential resilient outcomes are based on the interaction between genes and developmental experiences.
Childhood personality as a harbinger of competence and resilience in adulthood
Authors: Shiner Rebecca L. , Masten Ann S.
Published: April 2012

This study examined the significance of childhood Big Five personality traits for competence and resilience in early adulthood. Resilience was defined in terms of adaptive success in age-salient developmental tasks despite significant adversity throughout childhood/adolescence. The Project Competence Longitudinal Study tracked 205 young people from childhood (around age 10) to emerging adulthood (EA, age 20) and young adulthood (YA, age 30; 90% retention). Multimethod composites were created for personality traits, adversity exposure, and adult outcomes of academic achievement, work, rule-abiding conduct, friendship, and romantic relationships. Regressions showed significant main effects of childhood personality predicting adult outcomes, controlling for adversity, with few interaction effects. In person-focused analyses, the resilient group in EA and YA (high competence, high adversity) showed higher childhood conscientiousness, agreeableness, and openness and lower neuroticism than the maladaptive group (low competence, high adversity). The competent (high competence, low adversity) and resilient groups showed similar childhood traits. Turnaround cases, who changed from the maladaptive group in EA to the resilient group in YA, exhibited higher childhood conscientiousness than persistently maladaptive peers. Findings suggest that children on pathways to success in adulthood, whether facing low or high adversity, have capacities for emotion regulation, empathy and connection, dedication to schoolwork, and mastery and exploration.
The puzzle of schizophrenia: Tracking the core role of cognitive deficits
Authors: Nuechterlein Keith H. , Subotnik Kenneth L. , Ventura Joseph , Green Michael F. , Gretchen-Doorly Denise , Asarnow Robert F.
Published: April 2012

Cognitive deficits in schizophrenia are increasingly accepted as core features of this disorder that play a role as vulnerability indicators, as enduring abnormalities during clinical remission, and as critical rate-limiting factors in functional recovery. This article demonstrates the lasting influence of Norman Garmezy through his impact on one graduate student and then through his later collaborative research with colleagues. The promise of core cognitive deficits as vulnerability indicators or endophenotypes was demonstrated in research with children born to a parent with schizophrenia as well as with biological parents and siblings of individuals with schizophrenia. In studies of patients with a recent onset of schizophrenia, cognitive deficits were found to endure across psychotic and clinically remitted periods and to have a strong predictive influence on likelihood of returning successfully to work or school. Converging lines of evidence for the enduring core role of cognitive deficit in schizophrenia have led in recent years to a burgeoning interest in developing new interventions that target cognition as a means of improving functional recovery in this disorder.
Children and war: Risk, resilience, and recovery
Authors: Werner Emmy E.
Published: April 2012

This article reviews and reflects on studies that have explored the effects of war on children around the world. Most are cross-sectional and based on self-reports. They describe a range of mental health problems, related to dose effects and to the negative impact of being a victim or witness of violent acts, threats to and loss of loved ones, prolonged parental absence, and forced displacement. The more recent the exposure to war, and the older the child, the higher was the likelihood of reported posttraumatic stress disorder symptoms. Especially vulnerable to long-term emotional distress were child soldiers, children who were raped, and children who had been forcibly displaced. In adulthood, war-traumatized children displayed significantly increased risks for a wide range of medical conditions, especially cardiovascular diseases. Among protective factors that moderated the impact of war-related adversities in children were a strong bond between the primary caregiver and the child, the social support of teachers and peers, and a shared sense of values. Among the few documented intervention studies for children of war, school-based interventions, implemented by teachers or locally trained paraprofessionals, proved to be a feasible and low-cost alternative to individual or group therapy. More longitudinal research with multiple informants is needed to document the trajectories of risk and resilience in war-affected children, to assess their long-term development and mental health, and to identify effective treatment approaches.
Physiological correlates of peer victimization and aggression in African American urban adolescents
Authors: Kliewer Wendy , Dibble Ashley E. , Goodman Kimberly L. , Sullivan Terri N.
Published: April 2012

This study examined physiological correlates (cortisol and α-amylase [AA]) of peer victimization and aggression in a sample of 228 adolescents (45% male, 55% female; 90% African American; M age = 14 years, SD = 1.6 years) who participated in a longitudinal study of stress, physiology, and adjustment. Adolescents were classified into victimization/aggression groups based on patterns with three waves of data. At Wave 3, youth completed the Social Competence Interview (SCI), and four saliva samples were collected prior to, during, and following the SCI. Repeated-measures analyses of variance with victimization/aggression group as the predictor, and physiological measures as outcomes, controlling for time of day, pubertal status, and medication use revealed significant Group × SCI Phase interactions for salivary AA (sAA), but not for cortisol. The results did not differ by sex. For analyses with physical victimization/aggression, aggressive and nonaggressive victims showed increases in sAA during the SCI, nonvictimized aggressors showed a decrease, and the normative contrast group did not show any change. For analyses with relational victimization/aggression, nonaggressive victims were the only group who demonstrated sAA reactivity. Incorporating physiological measures into peer victimization studies may give researchers and clinicians insight into youth's behavior regulation, and help shape prevention or intervention efforts.
Affective and physiological responses to stress in girls at elevated risk for depression
Authors: Waugh Christian E. , Muhtadie Luma , Thompson Renee J. , Joormann Jutta , Gotlib Ian H.
Published: April 2012

Children of depressed parents are significantly more likely to develop depression and other mental health disorders than are children of never-depressed parents. Investigations of the physiological mechanisms underlying this elevated risk have generally focused on basal functioning. It is important to note, however, that physiological reactivity or responses to stress are also critical determinants of mental and physical health. In the current study, we examined whether children of depressed parents exhibit altered physiological responses to stress. In two studies, never-depressed adolescent daughters of either recurrently depressed mothers (RISK) or never-depressed mothers (CTL) underwent social stressors while their physiological responses were measured (cortisol in Study 1, heart rate in Study 2). In both studies, affective responses to the stressors predicted physiological responses in RISK girls, but not in never-depressed girls. For RISK girls, decreased positive affect in response to stress predicted increased cortisol reactivity; in addition, decreased positive affect and increased negative affect were associated with poorer heart rate recovery and habituation, respectively. Future research is needed to examine explicitly whether this coherence between affect and physiology is a mechanism underlying the increased risk for psychopathology in children of depressed parents.
Children's vagal regulatory capacity predicts attenuated sympathetic stress reactivity in a socially supportive context: Evidence for a protective effect of the vagal system
Authors: Wolff Brian C. , Wadsworth Martha E. , Wilhelm Frank H. , Mauss Iris B.
Published: April 2012

Social support and vagal regulatory capacity (VRC), an index of flexible vagal responses during various types of stress, are linked to attenuated stress responding and positive health outcomes. Guided by the polyvagal perspective, we tested whether children's VRC is associated with attenuated sympathetic nervous system (SNS) stress reactivity in socially supportive conditions. Sixty-one 4- to 5-year-old children living in poverty underwent two standardized laboratory stress induction procedures. Cardiac vagal reactivity (respiratory sinus arrhythmia) to a first set of stressors (social, cognitive, physical, and emotional) indexed VRC. During a second set of stressors, participants were randomly assigned to a supportive or nonsupportive social context, and cardiac sympathetic reactivity (preejection period) was assessed. We hypothesized VRC would predict lower SNS stress reactivity, but only in the socially supportive context. Children with high VRC showed attenuated SNS stress reactivity in the socially supportive context compared to children with high VRC in the nonsupportive context and children with low VRC in either context. Individual differences in VRC predict attenuated SNS stress reactivity in socially supportive conditions. Understanding how social support and VRC jointly mitigate SNS stress reactivity may further efforts to prevent negative health outcomes. Implications for biological sensitivity to context and differential susceptibility theories are discussed.