bluuebunny/crossref_metadata_2025 huggingface dataset:
Should high‐risk adolescents have Papanicolaou tests?
Authors: Ma Ly T. , Campbell Gerald A. , Richardson Gwyn , Schnadig Vicki J.
Published: March 2013

BACKGROUND

The current American College of Obstetricians and Gynecologists guidelines state that cervical cancer screening should begin at age 21 years, regardless of sexual or obstetric history. However, previous studies have demonstrated that there is a small but significant subset of high‐risk adolescents with extensive sexual and obstetric history who harbor a significant squamous cervical lesion. The objective of the current study was to use histologic and demographic data from adolescents (aged <21 years) who received Papanicolaou (Pap) tests to determine whether they benefited from early cervical cancer screening.

METHODS

Adolescent girls who had Pap tests between 2000 and 2010 were included in the study. Demographic data, including obstetric history, number of sexual partners, age of first coitus, age at first pregnancy, menarche, smoking history, and Chlamydia and syphilis infection, were analyzed for associations with levels of cervical dysplasia.

RESULTS

Of 56,785 adolescent Pap tests, 277 (0.5%) were diagnosed as high‐grade squamous HSIL, and 56 of those Pap tests (20%) were from patients who had grade 3 cervical intraepithelial neoplasia (CIN‐3) on subsequent biopsy and/or excision. One patient had microinvasive cervical carcinoma identified on loop electrosurgical excision procedure at age 27 years after an HSIL Pap test. Increased parity was associated significantly with higher rates of CIN‐3.

CONCLUSIONS

The study findings indicated that current American College of Obstetricians and Gynecologists guidelines to begin Pap testing at age 21 years are appropriate for the majority of adolescents, because the rate of HSIL is very low, and the risk for invasive carcinoma is minimal. Although higher parity was associated with a significantly increased grade of CIN, the conclusions are questionable because of the significant amount of missing demographic data points. That being said, this study should lead to other similar studies to determine any association of higher grade CIN with adolescent sexual and obstetric history. Cancer (Cancer Cytopathol) 2013;121:432–9. © 2013 American Cancer Society.
Potential therapeutic biomarkers in plasma cell myeloma: A flow cytometry study
Authors: Zheng Wenli , Liu Dingshen , Fan Xiangshan , Powers Linda , Goswami Maitrayee , Hu Ying , Lin Pei , Medeiros L. Jeffrey , Wang Sa A.
Published: March 2013

Objective

To investigate the expression profile of potential therapeutic biomarkers in plasma cell myeloma (PCM) by multicolor flow cytometry analysis.

Methods

Bone marrow (BM) specimens were collected consecutively and analyzed using a routine PCM panel (CD38/CD138/CD45/CD19/CD20/CD28/CD56/CD117, cyto‐kappa/lambda). The specimens were further assessed for CD30, CD44, CD49d, CD70, CD105, and CD184 expression in cases containing a substantial number of neoplastic plasma cells.

Results

Totally, 101 patient BM samples were assessed, including 58 men and 43 women, with a median age of 64 years (34–89). Twenty‐nine patients had newly diagnosed/untreated PCM, 40 had persistent/residual disease undergoing various therapies and 32 had relapsed disease. CD49d was expressed brightly and uniformly in all 45 patients tested. Expression of CD44 and CD184 was more variable with a median percentage of 77% (1–100) and 65% (5–100) respectively. Using an arbitrary 20% cutoff, CD44 was positive in 74 (73%) and CD184 in 92 (91%) cases with a mean fluorescence intensity ratio of 42.8 and 21.4. A higher CD44 expression was observed in patients with recurrent/persistent disease (P = 0.028). Additionally, both CD44 (P = 0.002) and CD184 (P = 0.026) showed higher expressions in CD117‐positive cases, but there was no correlation with cytogenetic groups. The CD30, CD70, and CD105 were expressed very infrequently in PCM, with a median expression of 0.2%, 0.2%, and 0.4% respectively.

Conclusions

CD49d, CD44, and CD184, are highly expressed in PCM. CD49d expression is bright and uniform, whereas CD44 and CD184 are more heterogeneous. In contrast, surface CD30, CD70, and CD105 are infrequent. These data provide useful preclinical information for the design of potential novel targeted therapies in PCM patients. © 2013 International Clinical Cytometry Society
Fine‐needle aspiration of metanephric adenoma of the kidney with clinical, radiographic and histopathologic correlation: A review
Authors: Blanco Luis Z. , Schein Caitlin O. , Patel Tushar , Heagley Dawn E. , Cimbaluk David J. , Reddy Vijaya , Gattuso Paolo
Published: March 2013

Metanephric adenoma of the kidney is an uncommon benign epithelial neoplasm with only a small number of reports that describe its cytologic features. We describe two additional cases of metanephric adenoma diagnosed on fine‐needle aspiration biopsy and review the available literature. Our cases showed similar cytology and were composed of cellular smears with numerous clusters of small, oval to round cells arranged in a microfollicular pattern and papillary configurations. The tumor cells had scant cytoplasm, fine chromatin and absent nucleoli. Psamomma bodies, nuclear atypia, cellular cpleomorphism, necrosis, and mitoses were absent. Because of the rarity of this tumor and the common cytologic features it shares with other lesions, including malignant tumors such as Wilms’ tumor and papillary renal cell carcinoma, awareness of the cytologic features of metanephric adenoma may aid in avoiding a diagnosis of malignancy, especially preoperatively, and in guiding the proper management for the patients. Diagn. Cytopathol. 2013;41:742–751. © 2013 Wiley Periodicals, Inc.
Shear‐induced permeability anisotropy of simulated serpentinite gouge produced by triaxial deformation experiments
Authors: Okazaki Keishi , Katayama Ikuo , Noda Hiroyuki
Published: March 2013

We have determined the permeability of antigorite serpentinite gouge in three orthogonal directions during frictional experiments using a triaxial gas apparatus to better understand fluid flow in subduction fault zones. The experiments were conducted at room temperature, a confining pressure of 150 MPa, a pore pressure of 100 MPa, and a constant slip rate of 0.58 µm/s. Although the initial permeabilities are similar in all directions, anisotropy develops during deformation, with the permeability normal to the shear plane becoming one order of magnitude lower than in the other directions when the shear stress reaches steady state. Formation of such permeability anisotropies may enhance fluid flow along the subduction plate interface and serpentinite‐bearing fault zones, important in evaluating potentially heterogeneous distribution of fluid pressure along the fault and in understanding the spatio‐temporal variation in the seismic activity.
Seasonality and magnitude of floods in Switzerland under future climate change
Authors: Köplin N. , Schädler B. , Viviroli D. , Weingartner R.
Published: March 2013

The flood seasonality of catchments in Switzerland is likely to change under climate change because of anticipated alterations of precipitation as well as snow accumulation and melt. Information on this change is crucial for flood protection policies, for example, or regional flood frequency analysis. We analysed projected changes in mean annual and maximum floods of a 22‐year period for 189 catchments in Switzerland and two scenario periods in the 21st century based on an ensemble of climate scenarios. The flood seasonality was analysed with directional statistics that allow assessing both changes in the mean date a flood occurs as well as changes in the strength of the seasonality. We found that the simulated change in flood seasonality is a function of the change in flow regime type. If snow accumulation and melt is important in a catchment during the control period, then the anticipated change in flood seasonality is most pronounced. Decreasing summer precipitation in the scenarios additionally affects the flood seasonality (mean date of flood occurrence) and leads to a decreasing strength of seasonality, that is a higher temporal variability in most cases. The magnitudes of mean annual floods and more clearly of maximum floods (in a 22‐year period) are expected to increase in the future because of changes in flood‐generating processes and scaled extreme precipitation. Southern alpine catchments show a different signal, though: the simulated mean annual floods decrease in the far future, that is at the end of the 21st century. Copyright © 2013 John Wiley & Sons, Ltd.
Biopolymer production in a fed‐batch reactor using optimal feeding strategies
Authors: Lai Song‐Yi , Kuo Po‐Chih , Wu Wei , Jang Ming‐Feng , Chou Yi‐Shyong
Published: March 2013

Background

Polyhydroxybutyrate (PHB), an important member of the family of polyhydroxyalkanoates (PHAs), is a biodegradable thermoplastic synthesized by numerous microorganisms under different cultivation conditions.

Results

A simple dynamic model for producing PHB in a fed‐batch reactor is presented. The kinetic model accuracy is quantified by the specific error measures. The dynamic manipulation scheme with prescribed stepwise changes is used to improve PHB productivity. A multi‐objective optimization algorithm is used to determine the optimal feeding strategy.

Conclusion

Reduced kinetic models in a mixed culture cultivation process for PHB production are successfully verified. An optimization‐based feeding strategy with stepwise changes has been derived and successfully validated. © 2013 Society of Chemical Industry
Simulating the surface energy balance over two contrasting urban environments using the Community Land Model Urban
Authors: Demuzere Matthias , Oleson Keith , Coutts Andrew M. , Pigeon Gregoire , van Lipzig Nicole P. M.
Published: March 2013

A single‐layer urban canopy model Community Land Model Urban (CLMU) is evaluated over two contrasting urban environments of Toulouse (France) and Melbourne (Australia). For the latter, three measurement sites are available characterized by a varying amount of vegetation, which supports a detailed assessment of the representation of urban vegetation in CLMU. For Toulouse, observed roof, wall and road surface temperatures allow for a detailed evaluation of the anthropogenic heat parameterization. Overall, CLMU performs well in simulating the canyon and urban surface temperatures, anthropogenic heat flux and urban energy balance, with an overall better performance for the dense old city centre of Toulouse in comparison to the more vegetated sites in Melbourne. Results for the latter sites reveal that the pervious road fraction provides a reasonable approximation of vegetation in the urban canyon while the tile approach often results in an underestimation of latent heat fluxes. A detailed analysis of the radiative, turbulent and anthropogenic heat fluxes as well as surface temperatures for Toulouse point to a complex interaction between urban surfaces and canyon properties. Decoupling the roof from the urban canyon to the atmosphere aloft is shown to be important. Our findings suggest that more evaluation is necessary for contrasting urban geometries in order to obtain a better understanding of the interaction between the roof surface on the one hand and canyon air and air aloft on the other hand. The results simultaneously reveal a trade‐off in errors between surface temperatures, radiative and turbulent fluxes and anthropogenic heat which again stresses the importance of the intended model application. Also, our results suggest that model complexity should, perhaps, relate to the site complexity. These results provide a robust basis for the construction of additional sensitivity experiments, tailored towards the intended application for urban climate mitigation studies.
On trace spaces of 2‐microlocal Besov spaces with variable integrability
Authors: Moura Susana D. , Neves Júlio S. , Schneider Cornelia
Published: March 2013

We study traces in 2‐microlocal Besov spaces with variable integrability on hyperplanes using atomic decompositions. Our results cover spaces of variable smoothness and also weighted spaces studied extensively in recent years.
Prevalence and clinical classification of tremor in elderly—A community‐based survey in Brazil
Authors: Barbosa Maira Tonidandel , Caramelli Paulo , Cunningham Mauro César Quintão , Maia Débora Palma , Lima‐Costa Maria Fernanda Furtado , Cardoso Francisco
Published: March 2013

Prevalence data on different types of tremor among the elderly population are very scarce. The objective of this study was to study the prevalence of tremor in a community‐dwelling elderly population in the town of Bambuí, Brazil. The authors studied 1186 inhabitants aged≥64 years. This was a 2‐phase study in which all participants who screened positive in a questionnaire for tremor and parkinsonism or who used drugs capable of causing/suppressing tremor were examined. In this population, the prevalence rate was 17.4% for tremor, 7.4% for essential tremor, 5.6% for parkinsonian tremor, 2.8% for enhanced physiological tremor, and 1.6% for other causes. There were no gender differences in prevalence rates for all types. Patients who had Parkinson's disease with tremor were older than those who had essential tremor, whereas patients who had enhanced physiological tremor were significantly younger. The age‐specific prevalence of tremor increased with advancing age for both men and women. The prevalence of tremor in the studied population was high and increased with advancing age. Essential tremor, parkinsonian tremor, and enhanced physiological tremor were the most commonly identified causes. © 2013 Movement Disorder Society
Prenatal chromosomal microarray analysis: a survey of prenatal genetic counselors' experiences and attitudes
Authors: Mikhaelian Marina , Veach Patricia McCarthy , MacFarlane Ian , LeRoy Bonnie S. , Bower Matthew
Published: March 2013

Objective

Studies showing the efficacy and accuracy of chromosomal microarray analysis (CMA) in prenatal diagnosis may position it as a first‐tier prenatal test. This study seeks to characterize the practices and attitudes of North American prenatal genetic counselors regarding CMA.

Method

Genetic counselors (N = 196) in Canada and the USA responded to an anonymous online survey. Completed surveys were analyzed (n = 160).

Results

Most respondents viewed CMA as useful (73%), presented CMA to patients (84%), and had ordered CMA at least once (69%). The use of full versus targeted arrays varied. Logistic regression analyses identified three significant predictors for the view that prenatal CMA is useful: more prenatal counseling experience, younger age, and previously presenting CMA to a patient. Three factors predicted the likelihood of offering CMA to prenatal patients: percentage of time spent in prenatal practice, belief that CMA is useful, and practicing in the USA (versus Canada). Reasons cited for not using CMA included financial concerns, the possibility of ambiguous results, and ethical concerns. Most respondents (n = 111) believed that ambiguous results are an ethical issue.

Conclusion

Clinical guidelines for prenatal CMA, further research on specific copy number variants, and broader availability of targeted arrays to reduce ambiguous results are needed. © 2013 John Wiley & Sons, Ltd.
Zinc Oxide Nanoparticles Induce Cell Filamentation in Escherichia coli
Authors: Gunawan Cindy , Teoh Wey Yang , Ricardo  , Marquis Christopher P. , Amal Rose
Published: March 2013

Zinc oxide nanoparticles (ZnO NPs) induce morphological transformation of Escherichia coli from its native rod‐shape of ≈2–4 μm to filamentous cells of 20–40 μm in length. The transient response can only be observed at up to 3.5 h proliferation, beyond which the cytotoxic effect is neutralized and the rod‐shape is restored. The filamentation is part of the bacterium SOS response to the Trojan horse‐type internalization of undissolved ZnO solids. In the absence of ZnO solids, no cell filamentation can be observed from the leached soluble zinc fraction or dissolved zinc salt.
AlGaN/GaN HEMTs with an InGaN back‐barrier grown by ammonia‐assisted molecular beam epitaxy
Authors: Rennesson S. , Damilano B. , Vennéguès P. , Chenot S. , Cordier Y.
Published: March 2013

We report on the study of AlGaN/GaN high electron mobility transistors (HEMTs) incorporating an InGaN back‐barrier grown by ammonia‐assisted molecular beam epitaxy (NH3‐MBE). The structural characterizations confirm the good crystalline quality of the heterostructure and the pseudomorphic growth of InGaN. This is also verified by the Hall effect mobility of about 2130 cm2 V−1 s−1. The associated two‐dimensional electron gas carrier concentration is in the range of 8 × 1012 cm−2 for heterostructures grown on GaN:Fe‐on‐sapphire templates. Normal DC transistor operation is observed. Similar results have been obtained on silicon substrates. To our knowledge, this is the first demonstration of AlGaN/GaN HEMTs with an InGaN back‐barrier grown by NH3‐MBE.
Experimental and theoretical study of electrical, thermal, and optical characteristics of InGaN/GaN high‐power flip‐chip LEDs
Authors: Chernyakov A. E. , Bulashevich K. A. , Karpov S. Yu. , Zakgeim A. L.
Published: March 2013

Comprehensive analysis of current spreading, temperature distribution, and near‐field electroluminescence (EL) of high‐power flip‐chip InGaN/GaN light‐emitting diodes (LEDs) has been performed by combination of experimental and theoretical methods. High‐resolution mapping of EL and thermal radiation was obtained by optical and infra‐red (IR) microscopes. Thermal resistance of the chip was measured by forward‐voltage relaxation technique. 3D coupled electrical, thermal, and optical simulations were carried out using hybrid 1D/3D model. The theoretical predictions agree well with available observations. The lateral distributions of the near‐field EL intensity and temperature are found to be qualitatively similar to that of the current density but to have substantially lower degree of non‐uniformity. Therefore, it becomes incorrect to judge the current crowding in the LED chip by the measured contrast of the EL image. The role of contact resistances in stabilization of the current spreading pattern is revealed by modeling.
Radiation resistance and generation of pinning centers in composite HTSC under heavy ion irradiation
Authors: Mikhailova Galina , Antonova Landysh , Troitskii Alexey , Didyk Alexander , Malginov Vladimir , Demikhov Timofey , Suvorova Elena
Published: March 2013

The effect of irradiation with heavy ions 40Ar8+ (48MeV), 132Xe27+ (167MeV) and 84Kr17+ (107 MeV) on the critical temperature (Tc) and critical current (Ic) of YBCO(123) composite tapes was investigated. It was found that threshold values were 5 × 1012 and 1 × 1013 ion/cm2 for 132Xe27+ and 84Kr17+ irradiation, correspondently. Critical current measured at T = 77 K increased for the lower 40Ar8+ and 84Kr17+ fluencies compared to the initial values.

The formation of radiation defects that could be effective pinning centers of Abrikosov vortices resulted in the increase of the critical current. The calculations of track diameters produced by 84Kr17+ ions with energy 1.2 MeV/amu in the composite YBCO tape showed the good agreement with the experimental ones. Transmission electron microscopy (TEM), high resolution TEM and scanning TEM were used to study defects induced by irradiation. The diameter of defects obtained from TEM was in the range from 3 to 5 nm. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nanotechnology for implantable sensors: carbon nanotubes and graphene in medicine
Authors: Wujcik Evan K. , Monty Chelsea N.
Published: March 2013

Implantable sensors utilizing nanotechnology are at the forefront of diagnostic, medical monitoring, and biological technologies. These sensors are often equipped with nanostructured carbon allotropes, such as graphene or carbon nanotubes (CNTs), because of their unique and often enhanced properties over forms of bulk carbon, such as diamond or graphite. Because of these properties, the fundamental and applied research of these carbon nanomaterials have become some of the most cited topics in scientific literature in the past decades. The age of carbon nanomaterials is simply budding, however, and is expected to have a major impact in many areas. These areas include electronics, photonics, plasmonics, energy capture (including batteries, fuel cells, and photovoltaics), and—the emphasis of this review—biosensors and sensor technologies. The following review will discuss future prospects of the two most commonly used carbon allotropes in implantable sensors for nanomedicine and nanobiotechnology, CNTs and graphene. Sufficient further reading and resources have been provided for more in‐depth and specific reading that is outside the scope of this general review. WIREs Nanomed Nanobiotechnol 2013, 5:233–249. doi: 10.1002/wnan.1213

This article is categorized under:

Diagnostic Tools > Biosensing

Implantable Materials and Surgical Technologies > Nanomaterials and Implants
Engineering multifunctional nanoparticles: all‐in‐one versus one‐for‐all
Authors: Huynh Elizabeth , Zheng Gang
Published: March 2013

Multifunctional nanoparticles have been developed to overcome the conventional hurdles associated with the diagnosis and treatment of disease. However, there are often caveats involved with the development and clinical translation of multifunctional nanoparticles largely regarding the notion that additional functionality increases nanoparticle complexity. Here, we discuss two design concepts, a conventional approach, ‘all‐in‐one’, and introduce the concept of ‘one‐for‐all’ to suggest that multifunctionality does not necessarily result in multicomponent complex nanoparticles. This review focuses on the design concepts of all‐in‐one and one‐for‐all with examples of each approach and a discussion on the implications for clinical translation. WIREs Nanomed Nanobiotechnol 2013, 5:250–265. doi: 10.1002/wnan.1217

This article is categorized under:

Therapeutic Approaches and Drug Discovery > Emerging Technologies

Diagnostic Tools > In Vivo Nanodiagnostics and Imaging

Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease
Estimating epistemic and aleatory uncertainties during hydrologic modeling: An information theoretic approach
Authors: Gong Wei , Gupta Hoshin V. , Yang Dawen , Sricharan Kumar , Hero Alfred O.
Published: March 2013

Key Points

Methods are provided to quantify information and uncertainty in data

Best achievable model performance for a given data set is estimated

Model adequacy is characterized in terms of Aleatory and Epistemic Uncertainties
Estimating the value of watershed services following forest restoration
Authors: Mueller Julie M. , Swaffar Wes , Nielsen Erik A. , Springer Abraham E. , Lopez Sharon Masek
Published: March 2013

Key Points

WTP for upland watershed restoration is $183.50/yr per household

Annual benefits of upland forest restoration are $400,000

Benefits have a policy application for forested watershed restoration
Sensitivity analysis of a time-delayed thermo-acoustic system via an adjoint-based approach
Authors: Magri Luca , Juniper Matthew P.
Published: March 2013

We apply adjoint-based sensitivity analysis to a time-delayed thermo-acoustic system: a Rijke tube containing a hot wire. We calculate how the growth rate and frequency of small oscillations about a base state are affected either by a generic passive control element in the system (the structural sensitivity analysis) or by a generic change to its base state (the base-state sensitivity analysis). We illustrate the structural sensitivity by calculating the effect of a second hot wire with a small heat-release parameter. In a single calculation, this shows how the second hot wire changes the growth rate and frequency of the small oscillations, as a function of its position in the tube. We then examine the components of the structural sensitivity in order to determine the passive control mechanism that has the strongest influence on the growth rate. We find that a force applied to the acoustic momentum equation in the opposite direction to the instantaneous velocity is the most stabilizing feedback mechanism. We also find that its effect is maximized when it is placed at the downstream end of the tube. This feedback mechanism could be supplied, for example, by an adiabatic mesh. We illustrate the base-state sensitivity by calculating the effects of small variations in the damping factor, the heat-release time-delay coefficient, the heat-release parameter, and the hot-wire location. The successful application of sensitivity analysis to thermo-acoustics opens up new possibilities for the passive control of thermo-acoustic oscillations by providing gradient information that can be combined with constrained optimization algorithms in order to reduce linear growth rates.
Interplay among unstable modes in films over permeable walls
Authors: Camporeale C. , Mantelli E. , Manes C.
Published: March 2013

The stability of open-channel flows (or film flows) has been extensively investigated for the case of impermeable smooth walls. In contrast, despite its relevance in many geophysical and industrial flows, the case that considers a permeable rather than an impermeable wall is almost unexplored. In the present work, a linear stability analysis of a film falling over a permeable and inclined wall is developed and discussed. The focus is on the mutual interaction between three modes of instability, namely, the well-known free-surface and hydrodynamic (i.e. shear) modes, which are commonly observed in open-channel flows over impermeable walls, plus a new one associated with the flow within the permeable wall (i.e. the porous mode). The flow in this porous region is modelled by the volume-averaged Navier–Stokes equations and, at the wall interface, the surface and subsurface flow are coupled through a stress-jump condition, which allows one to obtain a continuous velocity profile throughout the whole flow domain. The generalized eigenvalue problem is then solved via a novel spectral Galerkin method, and the whole spectrum of eigenvalues is presented and physically interpreted. The results show that, in order to perform an analysis with a full coupling between surface and subsurface flow, the convective terms in the volume-averaged equations have to be retained. In previous studies, this aspect has never been considered. For each kind of instability, the critical Reynolds number (${\mathit{Re}}_{c} $) is reported for a wide range of bed slopes ($\theta $) and permeabilities ($\sigma $). The results show that the free-surface mode follows the behaviour that was theoretically predicted by Benjamin and Yih for impermeable walls and is independent of wall permeability. In contrast, the shear mode shows a high dependence on $\sigma $: at $\sigma = 0$ the behaviour of ${\mathit{Re}}_{c} (\theta )$ recovers the well-known non-monotonic behaviour of the impermeable-wall case, with a minimum at $\theta \sim 0. 05\textdegree $. However, with an increase in wall permeability, ${\mathit{Re}}_{c} $ gradually decreases and eventually recovers a monotonic decreasing behaviour. At high values of $\sigma $, the porous mode of instability also occurs. A physical interpretation of the results is presented on the basis of the interplay between the free-surface-induced perturbation of pressure, the increment of straining due to shear with the increase in slope, and the shear stress condition at the free surface. Finally, the paper investigates the extent to which Squire’s theorem is applicable to the problem presented herein.
Nonlinear disturbance growth during sedimentation in dilute fibre suspensions
Authors: Zhang Feng , Dahlkild Anders A. , Lundell Fredrik
Published: March 2013

Disturbances in a dilute fibre suspension are studied with an Eulerian approach. Based on a linear stability analysis, it is shown that inertia and hydrodynamic diffusion damp perturbations at long wavelengths and short wavelengths, respectively, leading to a wavenumber selection. For small but finite Reynolds number of the fluid bulk motion, the most unstable wavenumber is a finite value, which increases with Reynolds number. Furthermore, the diffusion narrows the range of unstable wavenumbers. Numerical simulations of the full nonlinear evolution in time of a normal-mode perturbation show that the induced flow may either die out or saturate on a finite amplitude. The character of this long-time behaviour is dictated by the wavenumber and the presence or absence, as well as nature, of the translational and rotational diffusivities.
Generalized logarithmic law for high-order moments in turbulent boundary layers
Authors: Meneveau Charles , Marusic Ivan
Published: March 2013

High-Reynolds-number data in turbulent boundary layers are analysed to examine statistical moments of streamwise velocity fluctuations ${u}^{\prime } $. Prior work has shown that the variance of ${u}^{\prime } $ exhibits logarithmic behaviour with distance to the surface, within an inertial sublayer. Here we extend these observations to even-order moments. We show that the $2p$-order moments, raised to the power $1/ p, $ also follow logarithmic behaviour according to $\langle \mathop{({u}^{\prime + } ){}^{2p} \rangle }\nolimits ^{1/ p} = {B}_{p} - {A}_{p} \ln (z/ \delta )$, where ${u}^{\prime + } $ is the velocity fluctuation normalized by the friction velocity, $\delta $ is an outer length scale and ${B}_{p} $ are non-universal constants. The slopes ${A}_{p} $ in the logarithmic region appear quite insensitive to Reynolds number, consistent with universal behaviour for wall-bounded flows. The slopes differ from predictions that assume Gaussian statistics, and instead are consistent with sub-Gaussian behaviour.
Modelling circulation, impulse and kinetic energy of starting jets with non-zero radial velocity
Authors: Krieg Michael , Mohseni Kamran
Published: March 2013

The evolution of starting jet circulation, impulse and kinetic energy are derived in terms of kinematics at the entrance boundary of a semi-infinite axisymmetric domain. This analysis is not limited to the case of parallel jet flows; and the effect of non-zero radial velocity is specifically identified. The pressure distribution along the entrance boundary is also derived as it is required for kinetic energy modelling. This is done without reliance on an approximated potential function (i.e. translating flat plate), making it a powerful analytical tool for any axisymmetric jet flow. The pressure model indicates that a non-zero radial velocity is required for any ‘over-pressure’ at the nozzle exit. Jet flows are created from multiple nozzle configurations to validate this model. The jet is illuminated in cross-section, and velocity and vorticity fields are determined using digital particle image velocimetry (DPIV) techniques and circulation, impulse and kinetic energy of the jet are calculated from the DPIV data. A non-zero radial velocity at the entrance boundary has a drastic effect on the final jet. Experimental data showed that a specific configuration resulting in a jet with a converging radial velocity, with a magnitude close to 40 % of the axial velocity at its maximum, attains a final circulation which is 90–100 % larger than a parallel starting jet with identical volume flux and nozzle diameter, depending on the stroke ratio. The converging jet also attains a final impulse which is 70–75 % larger than the equivalent parallel jet and a final kinetic energy 105–135 % larger.
Modeling temperature-dependent survival with small datasets: insights from tropical mountain agricultural pests
Authors: Crespo-Pérez Verónica , Dangles Olivier , Régnière Jacques , Chuine Isabelle
Published: March 2013

Many regions are increasingly threatened by agricultural pests but suffer from a lack of data that hampers the development of adequate population dynamics models that could contribute to pest management strategies. Here, we present a new model relating pest survival to temperature and compare its performance with two published models. We were particularly interested in their ability to simulate the deleterious effect of extreme temperatures even when adjusted to datasets that did not include extreme temperature conditions. We adjusted the models to survival data of three species of potato tuber moth (PTM), some major pests in the Tropical Andes. To evaluate model performance, we considered both goodness-of-fit and robustness. The latter consisted in evaluating their ability to predict the actual altitudinal limits of the species in the Ecuadorian Andes. We found that even though our model did not always provide the best fit to data, it predicted extreme temperature mortality and altitudinal limits accurately and better than the other two models. Our study shows that the ability to accurately represent the physiological limits of species is important to provide robust predictions of invasive pests' potential distribution, particularly in places where temperatures approach lethal extremes. The value of our model lies in its ability to simulate accurate thermal tolerance curves even with small datasets, which is useful in places where adequate pest management is urgent but data are scarce.
The experience of family care-givers and migrant paid care-givers' relief of burden: a contrasted qualitative analysis
Authors: DE LA CUESTA-BENJUMEA CARMEN , ROE BRENDA
Published: March 2013

Older people are increasingly being cared for in the community across Europe. Dependent care in Spain largely remains a private issue involving family carers and migrant women from developing countries. Qualitative research on respite care has contributed to our understanding of respite as a subjective experience. Nonetheless, how care-givers relieve the burden of care is still not fully understood. Migrant care-givers are present in family life but their need for rest remains unseen. The aim of the study presented in this paper was to contrast family care-givers and migrant care-givers' strategies for relief from their caring role. Care-givers rest by thinking, doing and being but in a different manner from that of care-giving, that is: when they are a different person.To leave the life of care-givingis the general strategy that family care-givers use to rest from their care-giving selves whileturning to one's own worlddescribes the way migrant care-givers seek to relieve the burden of care. The comparative analysis shows that both strategies have in common the necessity to disconnect from the care-giving identity and that both migrant and family care-givers employ strategies that arefalse exits to a care-giving identity: they apparently relieve the burden of care. Respite goes beyond places, times and activities; as family care itself, it requires identity.
A two dimensional lattice of knots by C2m-moves
Authors: HORIUCHI SUMIKO , OHYAMA YOSHIYUKI
Published: March 2013

We consider a local move on a knot diagram, where we denote the local move by λ. If two knots K1 and K2 are transformed into each other by a finite sequence of λ-moves, the λ-distance between K1 and K2 is the minimum number of times of λ-moves needed to transform K1 into K2. A λ-distance satisfies the axioms of distance. A two dimensional lattice of knots by λ-moves is the two dimensional lattice graph which satisfies the following: the vertex set consists of oriented knots and for any two vertices K1 and K2, the distance on the graph from K1 to K2 coincides with the λ-distance between K1 and K2, where the distance on the graph means the number of edges of the shortest path which connects the two knots. Local moves called Cn-moves are closely related to Vassiliev invariants. In this paper, we show that for any given knot K, there is a two dimensional lattice of knots by C2m-moves with the vertex K.
Adapting environmental conservation legislation for an enlarged European Union: experience from the Habitats Directive
Authors: EVANS DOUGLAS , DEMETER ANDRÁS , GAJDOŠ PETER , HALADA ĽUBOŠ
Published: March 2013

The European Union's (EU's) Habitats Directive includes annexes listing the habitats and species requiring protection. As new countries join the EU these lists need to be amended to remain pertinent. In 2004 and 2007, 12 countries, mostly in central Europe, joined the EU and were asked to propose native species or habitats that required protection; this formed an initial base for negotiations with the European Commission in consultation with the existing member states and with scientific support from the European Topic Centre on Biological Diversity. The 12 countries made 831 proposals, resulting in the addition of 191 species and 33 habitats, and geographical exemptions for eight species. Although the Directive provided definitions, these needed to be supplemented with additional criteria to permit assessments of the proposals. The process involved many actors at both European and national level. This illustrates the development of biodiversity governance and provides potential lessons for future activities, including the need for scientific guidance and the importance of involving all relevant actors.
ZEROS OF THE ESTERMANN ZETA FUNCTION
Authors: DUBICKAS A. , GARUNKŠTIS R. , STEUDING J. , STEUDING R.
Published: March 2013

In this paper we investigate the zeros of the Estermann zeta function $E(s; k/ \ell , \alpha )= { \mathop{\sum }\nolimits}_{n= 1}^{\infty } {\sigma }_{\alpha } (n) \exp (2\pi ink/ \ell ){n}^{- s} $ as a function of a complex variable $s$, where $k$ and $\ell $ are coprime integers and ${\sigma }_{\alpha } (n)= {\mathop{\sum }\nolimits}_{d\vert n} {d}^{\alpha } $ is the generalized divisor function with a fixed complex number $\alpha $. In particular, we study the question on how the zeros of $E(s; k/ \ell , \alpha )$ depend on the parameters $k/ \ell $ and $\alpha $. It turns out that for some zeros there is a continuous dependency whereas for other zeros there is not.
Genetic and Environmental Influences on Longitudinal Changes in Leisure-Time Physical Activity From Adolescence to Young Adulthood
Authors: Aaltonen Sari , Ortega-Alonso Alfredo , Kujala Urho M. , Kaprio Jaakko
Published: March 2013

The aim of this study was to estimate genetic and environmental influences on the longitudinal evolution of leisure-time physical activity habits from adolescence to young adulthood. Data were gathered at four time points, at mean ages 16.2, 17.1, 18.6, and 24.5 years. At baseline, the sample comprised 5,216 monozygotic and dizygotic twins, born 1975–1979, and, at the last follow-up point, of 4,531 monozygotic and dizygotic twins. Physical activity volume was assessed as frequency of leisure-time physical activity and participants were categorized into three groups: inactive, moderately active, and active. Genetic and environmental influences were estimated using a multivariate, longitudinal Cholesky decomposition with a ‘multifactorial liability threshold’ approach. The results suggest that, in both sexes the heritability of leisure-time physical activity remained moderate (~43–52%) during adolescence, declining to ~30% in young adulthood. Shared environmental influences increased from adolescence (~18–26%) to young adulthood (43% in men and 49% in women). Specific environmental influences remained relatively stable during the total follow-up (~20–30%). New genetic, shared, and specific environmental influences at every follow-up point were suggested by the low correlations across occasions. In conclusion, the study demonstrated gender differences in genetic influences in the evolution of leisure-time physical activity habits from adolescence to young adulthood. However, shared environmental influences, especially in women, were crucial in explaining longitudinal changes in leisure-time physical activity. These outcomes emphasize the need of gender-specific measures to promote physical activity habits during young adulthood.
Feminist Subjectivity, Watered
Authors: Neimanis Astrida
Published: March 2013

Responding to Rosi Braidotti's call for more ‘conceptual creativity’ in thinking through contemporary feminist subjectivity, this paper proposes the figuration of the body of water. It begins with a critical materialist enhancement of Adrienne Rich's concept of a politics of location, followed by a schematised description of the various ‘hydro-logics’ in which our bodies partake. The ways in which these logics already inform diverse modes of feminist scholarship are then explored. The objective of this paper is to locate, at the confluence of these discourses and descriptions, an invigorated figuration of the feminist subject as body of water. This subject is posthumanist and material, both real and aspirational. Most importantly, she is responsively attuned to other watery bodies—both human and more-than-human—within global flows of political, social, cultural, economic and colonial planetary power.
Wick rotation for quantum field theories on degenerate Moyal space(-time)
Authors: Grosse Harald , Lechner Gandalf , Ludwig Thomas , Verch Rainer
Published: March 2013

In this paper the connection between quantum field theories on flat noncommutative space(-times) in Euclidean and Lorentzian signature is studied for the case that time is still commutative. By making use of the algebraic framework of quantum field theory and an analytic continuation of the symmetry groups which are compatible with the structure of Moyal space, a general correspondence between field theories on Euclidean space satisfying a time zero condition and quantum field theories on Moyal Minkowski space is presented (“Wick rotation”). It is then shown that field theories transferred to Moyal space(-time) by Rieffel deformation and warped convolution fit into this framework, and that the processes of Wick rotation and deformation commute.
Dynamics of the sub-Ohmic spin-boson model: A time-dependent variational study
Authors: Wu Ning , Duan Liwei , Li Xin , Zhao Yang
Published: March 2013

The Dirac-Frenkel time-dependent variation is employed to probe the dynamics of the zero temperature sub-Ohmic spin-boson model with strong friction utilizing the Davydov D1 ansatz. It is shown that initial conditions of the phonon bath have considerable influence on the dynamics. Counterintuitively, even in the very strong coupling regime, quantum coherence features still manage to survive under the polarized bath initial condition, while such features are absent under the factorized bath initial condition. In addition, a coherent-incoherent transition is found at a critical coupling strength α ≈ 0.1 for s = 0.25 under the factorized bath initial condition. We quantify how faithfully our ansatz follows the Schrödinger equation, finding that the time-dependent variational approach is robust for strong dissipation and deep sub-Ohmic baths (s ≪ 1).
The role of dimensionality in the decay of surface effects
Authors: Reuter Matthew G. , Boffi Nicholas M. , Ratner Mark A. , Seideman Tamar
Published: March 2013

We computationally investigate the decay of surface effects in one-, two-, and three-dimensional materials using two-band tight-binding models. These general models facilitate a direct comparison between materials of differing dimensionality, which reveals that material dimensionality (not material-specific chemistry/physics) is the primary factor controlling the decay of surface effects. Our results corroborate more sophisticated, material-specific studies, finding that surface effects decay after ∼10, ∼25, and ≳ 100 layers in three-dimensional, two-dimensional, and one-dimensional materials, respectively. Physically, higher-dimensional materials screen surface effects more efficiently, as theoretically described by integration over each layer's Brillouin zone. Finally, we discuss several implications of these results.
Thermal conductivity predictions of herringbone graphite nanofibers using molecular dynamics simulations
Authors: Khadem Masoud H. , Wemhoff Aaron P.
Published: March 2013

Non-equilibrium molecular dynamics (NEMD) simulations are used to investigate the thermal conductivity of herringbone graphite nanofibers (GNFs) at room temperature by breaking down the axial and transverse conductivity values into intralayer and interlayer components. The optimized Tersoff potential is used to account for intralayer carbon-carbon interactions while the Lennard-Jones potential is used to model the interlayer carbon-carbon interactions. The intralayer thermal conductivity of the graphene layers near room temperature is calculated for different crease angles and number of layers using NEMD with a constant applied heat flux. The edge effect on a layer's thermal conductivity is investigated by computing the thermal conductivity values in both zigzag and armchair directions of the heat flow. The interlayer thermal conductivity is also predicted by imposing hot and cold Nosé-Hoover thermostats on two layers. The limiting case of a 90° crease angle is used to compare the results with those of single-layer graphene and few-layer graphene. The axial and transverse thermal conductivities are then calculated using standard trigonometric conversions of the calculated intralayer and interlayer thermal conductivities, along with calculations of few-layer graphene without a crease. The results show a large influence of the crease angle on the intralayer thermal conductivity, and the saturation of thermal conductivity occurs when number of layers is more than three. The axial thermal conductivity, transverse thermal conductivity in the crease direction, and transverse thermal conductivity normal to the crease for the case of a five-layer herringbone GNF with a 45° crease angle are calculated to be 27 W/m K, 263 W/m K, and 1500 W/m K, respectively, where the axial thermal conductivity is in good agreement with experimental measurements.
Tunability of the terahertz space-charge modulation in a vacuum microdiode
Authors: Jonsson P. , Ilkov Marjan , Manolescu A. , Pedersen A. , Valfells A.
Published: March 2013

Under certain conditions, space-charge limited emission in vacuum microdiodes manifests as clearly defined bunches of charge with a regular size and interval. The frequency corresponding to this interval is in the terahertz range. In this computational study, it is demonstrated that, for a range of parameters, conducive to generating THz frequency oscillations, the frequency is dependant only on the cold cathode electric field and on the emitter area. For a planar micro-diode of given dimension, the modulation frequency can be easily tuned simply by varying the applied potential. Simulations of the microdiode are done for 84 different combinations of emitter area, applied voltage, and gap spacing, using a molecular dynamics based code with exact Coulomb interaction between all electrons in the vacuum gap, which is of the order 100. It is found, for a fixed emitter area, that the frequency of the pulse train is solely dependant on the vacuum electric field in the diode, described by a simple power law. It is also found that, for a fixed value of the electric field, the frequency increases with diminishing size of the emitting spot on the cathode. Some observations are made on the spectral quality, and how it is affected by the gap spacing in the diode and the initial velocity of the electrons.
Experimental evidence of staggered oxygen dimers as a component of boron-oxygen complexes in silicon
Authors: Chen Peng , Yu Xuegong , Liu Xiaoxia , Chen Xianzi , Wu Yichao , Yang Deren
Published: March 2013

We have investigated the relationship of the boron-oxygen (B-O) complexes to the staggered oxygen dimers (O2ist) in silicon. It is found that the saturated concentration of B-O complexes (Nt*) is proportional to the O2ist concentration ([O2ist]) in Czochralski silicon samples, whose [O2ist] are varied by annealing at different temperatures. This proportionality is further confirmed in a special silicon ingot with variable oxygen and carbon concentrations, in which the Nt* and [O2ist] show the similar dependences on the interstitial oxygen concentration. Therefore, our experimental data support that the O2ist should be an ingredient of the light-induced defects in silicon.