bluuebunny/crossref_metadata_2025 huggingface dataset:
Environmental enrichment for a mixed‐species nocturnal mammal exhibit
Authors: Clark Fay E. , Melfi Vicky A.
Published: March 2011

Environmental enrichment (EE) is an integral aspect of modern zoo animal management but, empirical evaluation of it is biased toward species housed in single‐species groups. Nocturnal houses, where several nocturnal species are housed together, are particularly overlooked. This study investigated whether three species (nine‐banded armadillos, Dasypus novemcinctus; Senegal bush babies, Galago senegalensis; two‐toed sloths, Choloepus didactylus) in the nocturnal house at Paignton Zoo Environmental Park, UK could be enriched using food‐based and sensory EE. Subjects were an adult male and female of each species. EE was deemed effective if it promoted target species‐typical behaviors, behavioral diversity, and increased use of enriched exhibit zones. Results from generalized linear mixed models demonstrated that food‐based EE elicited the most positive behavioral effects across species. One set of food‐based EEs (Kong®, termite mound and hanging food) presented together was associated with a significant increase in species‐typical behaviors, increased behavioral diversity, and increased use of enriched exhibit zones in armadillos and bush babies. Although one type of sensory EE (scented pine cones) increased overall exhibit use in all species, the other (rainforest sounds) was linked to a significant decrease in species‐typical behavior in bush babies and sloths. There were no intra or interspecies conflicts over EE, and commensalism occurred between armadillos and bush babies. Our data demonstrate that simple food‐based and sensory EE can promote positive behavioral changes in a mixed‐species nocturnal mammal exhibit. We suggest that both food and sensory EE presented concurrently will maximize opportunities for naturalistic activity in all species. Zoo Biol 31:397–413, 2012. © 2011 Wiley Periodicals, Inc.
High Surgical Morbidity Following Distal Pancreatectomy: Still an Unsolved Problem
Authors: Reeh Matthias , Nentwich Michael F. , Bogoevski Dean , Koenig Alexandra M. , Gebauer Florian , Tachezy Michael , Izbicki Jakob R. , Bockhorn Maximilian
Published: March 2011

Background

High surgical morbidity following distal pancreatectomy, especially pancreatic fistula, remains an unsolved problem. The aim of this study was to identify potential risk factors for surgical morbidity with a focus on the development of pancreatic fistula.

Methods

Clinicopathologic parameters were collected for 283 patients who underwent distal pancreatectomy between January 2000 and May 2010. Logistic regression analyses were performed to identify potential risk factors for surgical morbidity and pancreatic fistula.

Results

Spleen‐preserving pancreatectomy was carried out in 12% of all cases and multivisceral resections were performed in 37.8%. For closure of the pancreatic remnant, three different techniques were used: hand‐sewn suture in 44.5%, pancreaticojejunal anastomosis in 24%, and closure by stapler in 31.5%. Overall morbidity and mortality were 53 and 3.5%. Surgical morbidity was observed in 50.2% of all cases and pancreatic fistula in 24%. The stapling group had significantly higher surgical morbidity at 65.2% (p = 0.001) and the most pancreatic fistulas, though this did not reach statistical significance (p = 0.189). Univariate and multivariate logistic analyses indicated that closure by stapler [odds ratio (OR) = 3.61; p < 0.001] is a risk factor for surgical morbidity.

Conclusion

Closure of the pancreatic remnant by using a stapling device was associated with an increased risk of surgical morbidity. With an increasing number of laparoscopic distal pancreatectomies being performed, further studies analyzing the use of stapling devices and newer closure techniques are needed.
Impact of the Thoracoabdominal Approach on Peri‐ and Postoperative Outcomes of Hepatectomy for Hepatocellular Carcinoma
Authors: Okamura Yukiyasu , Takeda Shin , Fujii Tsutomu , Sugimoto Hiroyuki , Nomoto Shuji , Nakao Akimasa
Published: March 2011

Background

Resection of hepatocellular carcinoma (HCC) located in the right liver often requires hepatic mobilization. However, exposure of the HCC may be restricted when using the conventional abdominal approach (AA). In such cases, a thoracoabdominal approach (TA) can provide a good operating field. Although several studies have reported on the TA for hepatectomy for HCC, none have been published since 2003. Accordingly, this issue seemed to have been resolved, based on the advantages of this approach. However, surgical instruments are constantly improving and hepatectomy may be possible without the TA.

Methods

Data were retrospectively collected from 284 consecutive patients who underwent primary hepatectomy for HCC located in the right liver between January 1991 and December 2009. We compared the perioperative outcomes between patients who underwent the TA (n = 111) and those who underwent the AA (n = 173).

Results

Patient characteristics of both groups were comparable. The morbidity rate (Clavien grade ≥ 1) was significantly greater with the TA than with the AA (64.2 vs. 49.2%, p = 0.01), as was operative time (median = 370 vs. 315 min, p = 0.001) and hospital stay (median = 25 vs. 21 days, p = 0.005). There were no differences in hospital mortality or overall or disease‐free survival.

Conclusions

The TA provides no additional benefits over the AA in terms of safety and postoperative outcomes. We recommend that the TA should be used in exceptional circumstances because it resulted in a higher morbidity rate and longer operative time and postoperative hospitalization compared with the AA.
VEGF‐D Correlates with Metastatic Disease in Gastric Cancer Patients Undergoing Surgery
Authors: Schimanski Carl C. , Schlaegel Friederike , Jordan Mareike , Moehler Markus , Sgourakis George , Drescher Daniel G. , Galle Peter R. , Lang Hauke , Gockel Ines
Published: March 2011

Background

The present study was designed to evaluate the impact of the tyrosine kinase ligands VEGF‐A/C/D, PDGF‐A/B on tumor dissemination and survival in gastric cancer. This is the first study analyzing all these parameters in a homogeneous patient population undergoing surgery.

Methods

The expression pattern of VEGF‐A/C/D and PDGF‐A/B was analyzed by reverse transcriptase polymerase chain reaction (RT‐PCR) in 69 samples of human gastric adenocarcinoma and correlated with tumor stage and survival.

Results

Expression of the ligand VEGF‐D significantly correlated with distant metastatic disease (P = 0.00001) but not with patient survival. However, VEGF‐A inversely correlated with M1 and grading, PDGF‐A inversely correlated with pT and pN category. In contrast, VEGF‐C and PDGF‐B did not have an impact on clinicopathological parameters.

Conclusions

The ligand VEGF‐D, rather than the other ligands or tyrosine kinase receptors analyzed, is associated with progressive disease in gastric cancer patients undergoing surgery. The VEGF‐D ligand might be a helpful marker indicating disseminated disease, and targeting VEGF‐D may be a potential therapeutic strategy, although limitations imposed by the selected sample population have to be considered critically.
Tolerance of two invasive thistles to repeated disturbance
Authors: Zhang Rui , Heberling J. Mason , Haner Emily , Shea Katriona
Published: March 2011

Many invasive species have short life cycles, high reproduction, and easily dispersed offspring that make them good ruderal species under disturbance. However, the tolerance of such ruderal species to disturbance is often overlooked. In a 2‐year mowing study, we applied frequent intense disturbances to examine the tolerance of two congeneric invasive thistles, Carduus acanthoides and Carduus nutans, and potential differences in their responses. Our results show that both species can survive multiple mowing events, with C. acanthoides surviving repeated intense mowing through a whole season. Furthermore, C. acanthoides was found to adjust its growth form to the disturbance regime, and successfully overwintered and reproduced in the subsequent growing season if the disturbance was terminated. Our results support the idea that tolerance to disturbance should be considered when examining invasions by short‐lived monocarpic species, since avoidance of disturbance via rapid life cycle completion and seed production, and tolerance of disturbance via regrowth can co‐occur in these species. Consequently, management of short‐lived invasives should take both life history strategies into account.
Item Screening in Graphical Loglinear Rasch Models
Authors: Kreiner Svend , Christensen Karl Bang
Published: March 2011

In behavioural sciences, local dependence and DIF are common, and purification procedures that eliminate items with these weaknesses often result in short scales with poor reliability. Graphical loglinear Rasch models (Kreiner & Christensen, in Statistical Methods for Quality of Life Studies, ed. by M. Mesbah, F.C. Cole & M.T. Lee, Kluwer Academic, pp. 187–203, 2002) where uniform DIF and uniform local dependence are permitted solve this dilemma by modelling the local dependence and DIF. Identifying loglinear Rasch models by a stepwise model search is often very time consuming, since the initial item analysis may disclose a great deal of spurious and misleading evidence of DIF and local dependence that has to disposed of during the modelling procedure.

Like graphical models, graphical loglinear Rasch models possess Markov properties that are useful during the statistical analysis if they are used methodically. This paper describes how. It contains a systematic study of the Markov properties and the way they can be used to distinguish spurious from genuine evidence of DIF and local dependence and proposes a strategy for initial item screening that will reduce the time needed to identify a graphical loglinear Rasch model that fits the item responses. The last part of the paper illustrates the item screening procedure on simulated data and on data on the PF subscale measuring physical functioning in the SF36 Health Survey inventory.
Mild musculoskeletal and locomotor alterations in adult rats with white matter injury following prenatal ischemia
Authors: Delcour Maxime , Russier Michael , Xin Dong L. , Massicotte Vicky S. , Barbe Mary F. , Coq Jacques‐Olivier
Published: March 2011

Early brain injury including white matter damage (WMD) appears strongly correlated to perinatal hypoxia‐ischemia and adverse neurological outcomes in preterm survivors. Indeed, WMD has been widely associated with subtle to major motor disturbances, sensory, behavioral and cognitive impairments in preterm infants who afterward develop cerebral palsy (CP). Prenatal ischemia (PI) has been shown to reproduce the main features of WMD observed in preterm infants. The present study was aimed at determining in adult rats the impact of PI on brain axons, musculoskeletal histology and locomotor activity. PI was induced by unilateral intrauterine artery ligation at E17 in pregnant rats. We found axonal degeneration and reactive astrogliosis in several white matter regions of adult PI rats. We found mild myopathic and secondary joint changes, including increased variability in myofiber size in several hind limb muscles, decreased myofibers numbers but increased Pax 7 cells and myofiber size in the gastrocnemius, and mild knee and ankle chondromalacia. Although treadmill locomotion appeared normal, several kinematic parameters, such as stride length, amplitude, velocity and leg joint angles were altered in adult PI rats compared to shams. Using intra‐ and inter‐group variability of kinematic parameters, PI seemed to impair the maturation of locomotion on the treadmill. In addition, PI rats exhibited spontaneous hyperactivity in open‐field test. Musculoskeletal changes appeared concomitant with mild impairments in gait and posture. Our rodent model of WMD based on PI reproduces the mild motor deficits and musculoskeletal changes observed in many preterm infants with a perinatal history of hypoxia‐ischemia, and contributes towards a better understanding of the interplay between brain injury, musculoskeletal histopathology and gait disturbances encountered subsequently.
Neonatal exposure to genistein ameliorates high-fat diet-induced non-alcoholic steatohepatitis in rats
Authors: Huang Chengfei , Qiao Xubai , Dong Bing
Published: March 2011

Non-alcoholic steatohepatitis (NASH) is becoming a prevalent disease in developing countries with no effective therapy. Isoflavones such as genistein have been shown to prevent NASH in a rat model, but the effects of neonatal exposure to genistein on lipid metabolism have been rarely studied. In the present study, three doses of genistein (30, 300 or 1200 μg/rat per d) were injected (subcutaneously) into neonatal male Sprague–Dawley rats at postnatal days 1–5. After weaning, these rats were allowed free access to a high-fat diet for 6 weeks. The results demonstrate that NASH was induced by high fat feeding in the control rats, whereas genistein-treated rats displayed smaller body weight, and lower hepatic inflammation and steatosis. The mid dose of genistein was most effective. Neonatal exposure to genistein also resulted in a lower incidence of apoptotic cells in the liver. Additionally, neonatal genistein-treated rats showed lower hepatic expression of fatty acid synthase and sterol regulatory element-binding protein-1, but higher expression of PPARα, indicative of lower rates of lipid synthesis and higher rates of β-oxidation. These results indicate that neonatal treatment with genistein has a prolonged effect on hepatic lipid metabolism that is maintained post-weaning, offering a potential approach for the prevention of hepatic steatosis and NASH.
Avalokiteśvara's Manifestation as the Virgin Mary: The Jesuit Adaptation and the Visual Conflation in Japanese Catholicism after 1614
Authors: Shin Junhyoung Michael
Published: March 2011

Since St. Francis Xavier landed in Kagoshima in 1549, the Jesuit mission in Japan had achieved an amazing number of conversions, even though their activity lasted for merely about fifty years. Their great success came to an abrupt end in 1614 when the Bakufu government began the full proscription and persecution of the religion. An earlier ruler, Toyotomi Hideyoshi, had already banned Christianity and ordered the expulsion of foreign missionaries in 1587, but without strict enforcement. Since the 1630s, the former Christians were required to enroll in local Buddhist temples and annually go through the practice of treading on Christian icons in order to prove their apostasy. However, many Christians secretly retained the faith by disguising their true religious identity with Buddhist paraphernalia. These so-called “underground” (orsempuku) Christians survived more than two hundred years of persecution, and today some groups still continue to practice their own religion, refusing to join the Catholic Church. The present-day religion of the latter, called “hidden” (orkakure) Christians to distinguish them from the former, has drawn the attention of ample anthropological as well as religious studies.
Sheared-flow-driven vortices in a magnetized dusty electron–positron plasma
Authors: SHUKLA P. K. , FARID T. , STENFLO L. , ONISHCHENKO O. G.
Published: March 2011

It is shown that sheared plasma flows can generate nonthermal electrostatic
waves in a magnetized dusty electron–positron plasma. Linearly excited
modes attain large amplitudes and start interacting among themselves. Nonlinearly
coupled modes self-organize in the form of coherent vortices comprising a vortex
chain and a double vortex. Conditions under which the latter appear are given. The
relevance of our investigation to space, astrophysical, and laboratory plasmas is
pointed out.
Transport of energetic charged particles in a radial magnetic field. Part 1. Large-angle scattering
Authors: ZANK G. P. , LU J. Y. , RICE W. K. M. , WEBB G. M.
Published: March 2011

A new approach, the propagating-source method, is introduced to
solve the time-dependent Boltzmann equation. The method relies on the
decomposition of the particle distribution function into scattered and
unscattered particles. It is assumed in this paper that the particles are
transported in a constant-velocity spherically expanding supersonic flow (such
as the solar wind) in the presence of a radial magnetic field. Attention too has
been restricted to very fast particles. The present paper addresses only large-angle scattering, which is modelled as a BGK relaxation time operator. A
subsequent paper (Part 2) will apply the propagating-source method to a small-angle quasilinear scattering operator. Initially, we consider the simplest form of
the BGK Boltzmann equation, which omits both adiabatic deceleration and
focusing, to re-derive the well-known telegrapher equation for particle
transport. However, the derivation based on the propagating-source method
yields an inhomogeneous form of the telegrapher equation; a form for which
the well-known problem of coherent pulse solutions is absent. Furthermore, the
inhomogeneous telegrapher equation is valid for times t much smaller than the
‘scattering time’ τ, i.e. for times t [Lt ] τ, as
well as for t > τ. More complicated
forms of the BGK Boltzmann equation that now include focusing and adiabatic
deceleration are solved. The basic results to emerge from this new approach to
solving the BGK Boltzmann equation are the following. (i) Low-order
polynomial expansions can be used to investigate particle propagation and
transport at arbitrarily small times in a scattering medium. (ii) The theory of
characteristics for linear hyperbolic equations illuminates the role of causality
in the expanded integro-differential Fokker–Planck equation. (iii) The
propagating-source approach is not restricted to isotropic initial data, but
instead arbitrarily anisotropic initial data can be investigated. Examples using
different ring-beam distributions are presented. (iv) Finally, the numerical
scheme can include both small-angle and large-angle particle scattering
operators (Part 2). A detailed discussion of the results for the various
Boltzmann-equation models is given. In general, it is found that particle beams
that experience scattering by, for example, interplanetary fluctuations are
likely to remain highly anisotropic for many scattering times. This makes the
use of the diffusion approximation for charged-particle transport particularly
dangerous under many reasonable solar-wind conditions, especially in the inner
heliosphere.
A solitary-wave solution to a perturbed KdV equation
Authors: ALLEN M. A. , ROWLANDS G.
Published: March 2011

We derive the approximate form and speed of a solitary-wave
solution to a perturbed KdV equation. Using a conventional perturbation
expansion, one can derive a first-order correction to the solitary-wave speed,
but at the next order, algebraically secular terms appear, which produce
divergences that render the solution unphysical. These terms must be treated by
a regrouping procedure developed by us previously. In this way, higher-order
corrections to the speed are obtained, along with a form of solution that is
bounded in space. For this particular perturbed KdV equation, it is found that
there is only one possible solitary wave that has a form similar to the
unperturbed soliton solution.
Pressure determinations for incompressible fluids and magnetofluids
Authors: KRESS BRIAN T. , MONTGOMERY DAVID C.
Published: March 2011

Certain unresolved ambiguities surround pressure determinations for
incompressible flows: both Navier–Stokes and magnetohydrodynamic (MHD).
For uniform-density fluids with standard Newtonian viscous terms, taking the
divergence of the equation of motion leaves a Poisson equation for the pressure
to be solved. But Poisson equations require boundary conditions. For the case
of rectangular periodic boundary conditions, pressures determined in this way
are unambiguous. But in the presence of ‘no-slip’ rigid walls, the equation of
motion can be used to infer both Dirichlet and Neumann boundary conditions
on the pressure P, and thus amounts to an over-determination. This has
occasionally been recognized as a problem, and numerical treatments of wallbounded shear flows
usually have built in some relatively ad hoc dynamical
recipe for dealing with it – often one that appears to ‘work’ satisfactorily. Here
we consider a class of solenoidal velocity fields that vanish at no-slip walls, have
all spatial derivatives, but are simple enough that explicit analytical solutions
for P can be given. Satisfying the two boundary conditions separately gives two
pressures, a ‘Neumann pressure’ and a ‘Dirichlet pressure’,
which differ nontrivially at the initial instant, even before any dynamics are implemented. We
compare the two pressures, and find that, in particular, they lead to different
volume forces near the walls. This suggests a reconsideration of no-slip
boundary conditions, in which the vanishing of the tangential velocity at a no-slip
wall is replaced by a local wall-friction term in the equation of motion.
Arabic influences on Tigre: A preliminary evaluation
Authors: Bulakh Maria , Kogan Leonid
Published: March 2011

Tigre, an Ethio-Semitic language spoken in Eritrea by a predominantly Muslim population, is known to have remained in intensive contact with Arabic since at least the nineteenth century. In the present article we attempt to survey the lexical and grammatical features of Tigre which are potentially attributable to Arabic influence. The genealogical proximity of Arabic and Ethio-Semitic complicates the task, as borrowed features and common retentions are not always easily distinguishable. In the lexical domain, the Arabic impact is undoubtedly conspicuous: thus, even in the core vocabulary Arabic loanwords are more prominent than in any other Ethio-Semitic language. Nevertheless, for many individual lexemes the borrowing hypothesis remains to be substantiated. Recent Arabic influence is probably responsible for a few relatively superficial features of Tigre phonetics and morphology. Several more deeply-rooted features may in principle be due to a more ancient and more intensive contact with Arabic: the specific influence of the ejectives on the vowels; the grammatical categories of singulative and diminutive; the diversity of verbal noun patterns in the basic stem; and several types of broken plural formation.
Medieval Arabic accounts of the conquest of Cordoba: Creating a narrative for a provincial capital
Authors: Clarke Nicola
Published: March 2011

Like most early Islamic history writing, the tradition surrounding the Muslim conquest of the Iberian Peninsula in 711 is the product of later debates and priorities rather than a true reflection of eighth-century circumstances. Rather than seek to reconstruct what is lost, this article explores what the sources have to tell us about these later priorities: that is, what the authors, their patrons and their wider environment valued in the history that they retold. Its focus is the conquest of Cordoba, narratives about which entered the tradition in the tenth century, as a result of the patronage of history writing by the Umayyad caliphsʿAbd al-Raḥmān III (r. 912–61) and al-Ḥakam II (r. 961–76). These tenth-century narratives are expressions of both caliphal ideology and the writers' own status in their society.
BLOCK BOOTSTRAP HAC ROBUST TESTS: THE SOPHISTICATION OF THE NAIVE BOOTSTRAP
Authors: Gonçalves Sílvia , Vogelsang Timothy J.
Published: March 2011

This paper studies the properties of naive block bootstrap tests that are scaled by zero frequency spectral density estimators (long-run variance estimators). The naive bootstrap is a bootstrap where the formula used in the bootstrap world to compute standard errors is the same as the formula used on the original data. Simulation evidence shows that the naive bootstrap can be much more accurate than the standard normal approximation. The larger the HAC bandwidth, the greater the improvement. This improvement holds for a large number of popular kernels, including the Bartlett kernel, and it holds when the independent and identically distributed (i.i.d.) bootstrap is used and yet the data are serially correlated. Using recently developed fixed-b asymptotics for HAC robust tests, we provide theoretical results that can explain the finite sample patterns. We show that the block bootstrap, including the special case of the i.i.d. bootstrap, has the same limiting distribution as the fixed-b asymptotic distribution. For the special case of a location model, we provide theoretical results that suggest the naive bootstrap can be more accurate than the standard normal approximation depending on the choice of the bandwidth and the number of finite moments in the data. Our theoretical results lay the foundation for a bootstrap asymptotic theory that is an alternative to the traditional approach based on Edgeworth expansions.
Young children's understanding of markedness in non-verbal communication*
Authors: LIEBAL KRISTIN , CARPENTER MALINDA , TOMASELLO MICHAEL
Published: March 2011

Speakers often anticipate how recipients will interpret their utterances. If they wish some other, less obvious interpretation, they may ‘mark’ their utterance (e.g. with special intonations or facial expressions). We investigated whether two- and three-year-olds recognize when adults mark a non-verbal communicative act – in this case a pointing gesture – as special, and so search for a not-so-obvious referent. We set up the context of cleaning up and then pointed to an object. Three-year-olds inferred that the adult intended the pointing gesture to indicate that object, and so cleaned it up. However, when the adult marked her pointing gesture (with exaggerated facial expression) they took the object's hidden contents or a hidden aspect of it as the intended referent. Two-year-olds' appreciation of such marking was less clear-cut. These results demonstrate that markedness is not just a linguistic phenomenon, but rather something concerning the pragmatics of intentional communication more generally.
Anorexia nervosa and nutritional assessment: contribution of body composition measurements
Authors: Mattar Lama , Godart Nathalie , Melchior Jean Claude , Pichard Claude
Published: March 2011

The psychiatric condition of patients suffering from anorexia nervosa (AN) is affected by their nutritional status. An optimal assessment of the nutritional status of patients is fundamental in understanding the relationship between malnutrition and the psychological symptoms. The present review evaluates some of the available methods for measuring body composition in patients with AN. We searched literature in Medline using several key terms relevant to the present review in order to identify papers. Only articles in English or French were reviewed. A brief description is provided for each body composition technique, with its applicability in AN as well as its limitation. All methods of measuring body composition are not yet validated and/or feasible in patients with AN. The present review article proposes a practical approach for selecting the most appropriate methods depending on the setting, (i.e. clinicalv.research) and the goal of the assessment (initialv.follow-up) in order to have a more personalised treatment for patients suffering from AN.
Kant On Moral Agency and Women's Nature
Authors: Mikkola Mari
Published: March 2011

Some commentators have condemned Kant's moral project from a feminist perspective based on Kant's apparently dim view of women as being innately morally deficient. Here I will argue that although his remarks concerning women are unsettling at first glance, a more detailed and closer examination shows that Kant's view of women is actually far more complex and less unsettling than that attributed to him by various feminist critics. My argument, then, undercuts the justification for the severe feminist critique of Kant's moral project.
The Moral Value of Artistic Beauty in Kant
Authors: Cannon Joseph
Published: March 2011

In the thirdCritique, Kant argues that it is “always the mark of a good soul” to take an immediate interest in natural beauty, because it indicates an interest in harmony between nature and moral freedom. He, however, denies that there can be a similarly significant interest in artistic beauty. I argue that Kant ought not to deny this value to artistic beauty because his account of fine art as the joint product of the “natural gift” of genius and the discipline of taste commits him to the claim that artistic beauty expresses such a harmony between nature and freedom.
Simulation of a Luneburg Lens using a broadband Multilevel Fast Multipole Algorithm
Authors: Michiels Bart , Bogaert Ignace , Fostier Jan , Peeters Joris , De Zutter Daniël
Published: March 2011

In this paper, the full wave simulation of a 2‐D Luneburg lens is reported, using the Multilevel Fast Multipole Algorithm (MLFMA). To stabilize the MLFMA at low frequencies, it is augmented with a normalized plane‐wave method, yielding a fully broadband solver. To test the proposed method, the Luneburg lens is partitioned into concentric shells with a constant permittivity, resulting in a complex simulation target that consists of multiple embedded dielectric objects. The numerical results are in good agreement with the analytical solutions for both the continuous and discretized lens.
Decreased expression of DNAM‐1 on NK cells from acute myeloid leukemia patients
Authors: Sanchez‐Correa Beatriz , Gayoso Inmaculada , Bergua Juan M , Casado Javier G , Morgado Sara , Solana Rafael , Tarazona Raquel
Published: March 2011

This study tested the hypothesis that the expression of CD112 and CD155 (DNAM‐1 ligands) on leukemic blasts induces a decreased expression of the activating receptor DNAM‐1 on natural killer (NK) cells from acute myeloid leukemia (AML) patients. DNAM‐1 is a co‐receptor involved in the activation of NK cell cytotoxicity after its interaction with its ligands CD112 and CD155 on target cells. Here we study the expression of DNAM‐1 on NK cells and DNAM‐1 ligands on blasts from AML patients stratified by age. The results demonstrate that NK cells from AML patients younger than 65 years have a reduced expression of DNAM‐1 compared with age‐matched controls. The analysis of DNAM‐1 ligands showed a high expression of CD112 and CD155 on leukemic blasts. An inverse correlation between CD112 expression on leukemic blasts and DNAM‐1 expression on NK cells was found. Furthermore, downregulation of DNAM‐1 was induced on healthy donors’ NK cells after in vitro culture with leukemic blasts expressing DNAM‐1 ligands. In conclusion, these results support the hypothesis that receptor–ligand crosslinking downregulates DNAM‐1 expression on NK cells from patients <65 years of age. Considering the relevance of DNAM‐1 in NK recognition and killing of leukemic cells, the reduced expression of this receptor on NK cells from AML patients can represent an additional mechanism of tumor escape.
Industrial applications of photochemistry: automotive coatings and beyond
Authors: Dietliker Kurt , Braig Adalbert , Ricci Andrea
Published: March 2011

Photochemistry is an essential tool in both the manufacturing and the use of modern cars. Radiation curing is used as a very efficient, economically and ecologically attractive technology for the coating and bonding of many of the parts used in a car, and avoiding degradation of the coating due to photoinduced processes during the foreseen service time is a key issue. Ecological heat management and the OLED technology used for lightening and signage are further examples of useful exploitation of light-induced effects. This paper reviews new photochemistry-related developments such as radiation curing of automotive coatings on the three-dimensional car body, and gives an outlook on future developments.
Local heating of heterogeneous current-carrying conductors
Authors: Dolinsky Yu. , Elperin T.
Published: March 2011

We study the heating of current-carrying conductors with inclusions when the kinetic coefficients of inclusions are different from those of the conductor. It is shown that if the surface temperature of the conductor is maintained constant and the thermal conductivity of the inclusion is higher than the thermal conductivity of the conductor, the temperature distribution in the vicinity of the inclusion is strongly different from the temperature distribution in a homogeneous conductor. Depending on the parameters of the system the temperature at the location of an inclusion can be two times higher than the temperature at the same location without an inclusion. We investigate the behavior of the temperature difference as a function of the distance between the center of the spherical inclusion and the conductor’s surface. We analyze different components of Joule heating, which are associated with the change of the configuration of the electric current caused by the inclusion and with the change of temperature distribution caused by different thermal conductivities of the conductor and inclusion. We consider a stationary regime of conductor heating whereby the surface temperature of the conductor is kept constant in time, and the case of a thermally insulated conductor. It is demonstrated that in the latter case the temperature of the inclusion can be considerably lower than the surface temperature of the conductor.
X-ray enhancement in a nanohole target irradiated by intense ultrashort laser pulses
Authors: Chakravarty U. , Arora V. , Chakera J. A. , Naik P. A. , Srivastava H. , Tiwari P. , Srivastava A. , Gupta P. D
Published: March 2011

In this paper, we present a comparative study of the laser energy absorption, soft x-ray emission (in the water window region: 2.3–4.4 nm) and hard x-ray emission (in the 2–20 keV range) from planar aluminum and nanohole alumina of 40 nm average diameter, when irradiated by Ti:sapphire laser pulses. The laser pulse duration was varied from 45 to 500 fs, and the focused intensity on the target ranged from ∼3 × 1016 W/cm2 to 3×1017 W/cm2. The x-ray yield enhancement from the nanoholes shows an increased coupling of the laser energy to the target. The effect of laser pulse duration on the x-ray emission was also studied, where a resonance like phenomenon was observed. The laser energy absorption measurements in the nanoholes showed a marginal enhancement in absorption as compared to planar Al. The integrated keV x-ray yield, from nanohole alumina and planar Al, at an intensity of 3 × 1017 W/cm2, was 25 and 3.5 μJ, respectively. The results can be explained by considering the hydrodynamic expansion of the laser irradiated structure and field enhancement in the nanoholes.
Molecular friction dissipation and mode coupling in organic monolayers and polymer films
Authors: Knorr Daniel B. , Widjaja Peggy , Acton Orb , Overney René M.
Published: March 2011

The impact of thermally active molecular rotational and translational relaxation modes on the friction dissipation process involving smooth nano-asperity contacts has been studied by atomic force microscopy, using the widely known Eyring analysis and a recently introduced method, dubbed intrinsic friction analysis. Two distinctly different model systems, i.e., monolayers of octadecyl-phosphonic acid (ODPA) and thin films of poly(tert-butyl acrylate) (PtBA) were investigated regarding shear-rate critical dissipation phenomena originating from diverging mode coupling behaviors between the external shear perturbation and the internal molecular modes of relaxation. Rapidly (ODPA) versus slowly (PtBA) relaxing systems, in comparison to the sliding rate, revealed monotonous logarithmic and nonmonotonous spectral shear rate dependences, respectively. Shear coupled, enthalpic activation energies of 46 kJ/mol for ODPA and of 35 and ∼65 kJ/mol for PtBA (below and above the glass transition) were found that could be attributed to intrinsic modes of relaxations. Also, entropic energies involved in the cooperative backbone mobility of PtBA could be quantified, dwarfing the activation energy by more than a factor of five. This study provides (i) a material specific understanding of the molecular scale dissipation process in shear compliant substances, (ii) analyses of material intrinsic shear-rate mode coupling, shear coordination and energetics, (iii) a verification of Eyring's model applied to tribological systems toward material intrinsic specificity, and (iv) a valuable extension of the Eyring analysis for complex macromolecular systems that are slowly relaxing, and thus, exhibit shear-rate mode coupling.
Structure and morphology of coevaporated pentacene-perfluoropentacene thin films
Authors: Hinderhofer A. , Frank C. , Hosokai T. , Resta A. , Gerlach A. , Schreiber F.
Published: March 2011

The structural properties of coevaporated thin films of pentacene (PEN) and perfluoropentacene (PFP) on SiO2 were studied using x-ray reflectivity and grazing incidence x-ray diffraction. Reciprocal space maps of the coevaporated thin films with different volume fractions reveal the coexistence of two different molecular mixed PEN-PFP phases together with the pure PEN and PFP crystallites. The crystal structure of PEN:PFP blends does not change continuously with volume fraction, instead the proportion of the appropriate phases changes, as seen from the diffraction analysis. Additional temperature dependent experiments reveal that the fraction of the two mixed PEN-PFP phases varies with growth temperature. The λ-phase (molecular plane parallel to the substrate) is metastable and induced by low growth temperature. The σ-phase (molecular plane nearly perpendicular to the substrate) is thermally stable and nucleates predominantly at high growth temperatures.
Stabilization of ambient sensitive atomic layer deposited lanthanum aluminates by annealing and in situ capping
Authors: Swerts J. , Gielis S. , Vereecke G. , Hardy A. , Dewulf D. , Adelmann C. , Van Bael M. K. , Van Elshocht S.
Published: March 2011

We have studied the effect of air exposure on lanthanum aluminates (LaAlOx) deposited by atomic layer deposition. Fourier transform infrared spectroscopy and thermal desorption spectroscopy of as-deposited LaAlOx showed that H2O is absorbed during air exposure and that the amount of absorbed H2O increases with increasing La atomic percent. C was found to be incorporated already during deposition in the form of carbonates. H2O and CO2 are outgassed during postdeposition annealing in an inert atmosphere. After a 700 °C postdeposition anneal, the LaAlOx becomes resistant against H2O absorption due to film densification. Alternatively, in situ capping of the LaAlOx with a ∼2 nm thin Al2O3 film protects the LaAlOx against H2O absorption, but it also hinders the outgassing of the C contaminants during a postdeposition anneal.
Polynomial constants of motion for Calogero-type systems in three dimensions
Authors: Chanu Claudia , Degiovanni Luca , Rastelli Giovanni
Published: March 2011

We give an explicit and concise formula for higher degree polynomial first integrals of a family of Calogero-type Hamiltonian systems in dimension three. These first integrals, together with the already known ones, prove the maximal superintegrability of the systems.
Nonlinear dynamics of confined thin liquid-vapor bilayer systems with phase change
Authors: Kanatani Kentaro , Oron Alexander
Published: March 2011

We numerically investigate the nonlinear evolution of the interface of a thin liquid-vapor bilayer system confined by rigid horizontal walls from both below and above. The lateral variation of the vapor pressure arising from phase change is taken into account in the present analysis. When the liquid (vapor) is heated (cooled) and gravity acts toward the liquid, the deflection of the interface monotonically grows, leading to a rupture of the vapor layer, whereas nonruptured stationary states are found when the liquid (vapor) is cooled (heated) and gravity acts toward the vapor. In the latter case, vapor-flow-driven convective cells are found in the liquid phase in the stationary state. The average vapor pressure and interface temperature deviate from their equilibrium values once the interface departs from the flat equilibrium state. Thermocapillarity does not have a significant effect near the thermodynamic equilibrium, but becomes important if the system significantly deviates from it.
Modulation of volume fraction results in different kinetic effects in Belousov–Zhabotinsky reaction confined in AOT-reverse microemulsion
Authors: Villar Álvarez Eva , Carballido-Landeira Jorge , Guiu-Souto Jacobo , Taboada Pablo , Muñuzuri Alberto P.
Published: March 2011

The effects of volume fraction modulations on a Belousov–Zhabotinsky reaction catalyzed by the photosensitive Ru(bpy)3+2 confined in an AOT microemulsion system are analyzed. Kinetic observables such as the induction time or the initial oscillation period demonstrate two different types of correlation with the volume fraction depending on whether the system is below or above the microemulsion percolation threshold. Temporal evolution also demonstrates an exponential growth of the period with the number of oscillations independent of the volume fraction of the system.
Micromagnetic study of switching boundary of a spin torque nanodevice
Authors: Zhou Yan , Åkerman Johan , Sun Jonathan Z.
Published: March 2011

We report on a numerical study of the micromagnetic switching process of a nanostructured spin torque device. We show that incoherent spin waves can be excited over a wide range of current and field even at zero temperature. These large amplitude, incoherent, and nonzero k spin wave modes are shown to alter the switching phase boundary from that calculated within a macrospin model. The presence of telegraphic transitions between different spin wave modes may also contribute to the so-called back-hopping phenomenon where the switching probability varies nonmonotonically with increasing bias current.
Evidence of hydrogen-mediated ferromagnetic coupling in Mn-doped ZnO
Authors: Park Jun Kue , Won Lee Kyu , Kweon Hyocheon , Lee Cheol Eui
Published: March 2011

Hydrogen shallow donors in undoped and doped ZnO systems have been studied by means of the electron paramagnetic resonance and nuclear magnetic resonance measurements. Experimental evidence is given in this work for coupling of hydrogen shallow donors and Mn ions in Mn-doped ZnO mediating short-range ferromagnetic spin-spin interaction.
Two-color In0.4Ga0.6As/Al0.1Ga0.9As quantum dot infrared photodetector with double tunneling barriers
Authors: Huang Jianliang , Ma Wenquan , Wei Yang , Zhang Yanhua , Huo Yongheng , Cui Kai , Chen Lianghui
Published: March 2011

We report a two-color quantum dot infrared photodetector (QDIP) using double tunneling barriers (DTBs) on one side of the InGaAs/AlGaAs dots. The two-color detection is achieved by changing the polarity of the applied bias voltages. In contrast, the same QDIP structure without the DTBs does not exhibit this detection wavelength tunability by switching the bias polarity. The two-color detection is ascribed to a different escape mechanism of electrons between positive and negative biases. The electrons escape out of the quantum well through resonant tunneling for a positive bias voltage while tunnel through a triangular barrier for a negative bias voltage.
Numerical study of 1.1 GeV electron acceleration over a-few-millimeter-long plasma with a tapered density
Authors: Hur Min Sup , Suk Hyyong
Published: March 2011

We present two-dimensional particle-in-cell simulations of laser wakefield electron acceleration up to 1.1 GeV over a-few-millimeter-long plasma with the help of density tapering. We observed that, in a uniform plasma, the electron beam reaches the dephasing state not only by the slow phase velocity of the wakefield but also by the relativistic prolonging of the plasma wavelength. Such a dephasing between the wakefield and beam can be mitigated by an upward density taper. By employing a parabolically increasing plasma density, we obtained a significant enhancement of the beam energy from 850 MeV (uniform) to 1.1 GeV (tapered). However, the similar relativistically promoted dephasing was observed again in the environment of tapered density. Over a few millimeters the driving laser pulse was well self-guided without any externally prepared channel. Thus, this parameter regime is suitable for the gas-jet laser wakefield electron acceleration experiments.
Gain enhancement in a terahertz quantum cascade laser with parylene antireflection coatings
Authors: Rungsawang R. , Jukam N. , Maysonnave J. , Cavalié P. , Madéo J. , Oustinov D. , Dhillon S. S. , Tignon J. , Gellie P. , Sirtori C. , Barbieri S. , Beere H. E. , Ritchie D. A.
Published: March 2011

We study the effect of parylene antireflection coatings on the gain of a 2.8 THz quantum cascade laser using terahertz time-domain spectroscopy. With antireflection coatings the threshold current increases as the mirror losses are increased, and the gain clamps at 16 cm−1, compared to 10 cm−1 for an uncoated device. These values are consistent with a drop in reflectivity from 0.320 to 0.053 as a consequence of the coating deposition. Further improvements could reveal the bare cavity gain and permit the quantum cascade laser to be used as an efficient terahertz amplifier.
Pure anatase TiO2 “nanoglue”: An inorganic binding agent to improve nanoparticle interconnections in the low-temperature sintering of dye-sensitized solar cells
Authors: Li Yuelong , Lee Wonjoo , Lee Doh-Kwon , Kim Kyungkon , Park Nam-Gyu , Ko Min Jae
Published: March 2011

An interparticle-binding agent, or “nanoglue,” was prepared for the fabrication of well-interconnected TiO2 photoelectrodes in dye-sensitized solar cells (DSSCs) sintered at low temperature. This nanoglue consisted of pure anatase particles approximately 5 nm in diameter dispersed in alcoholic solvent. When mixed with TiO2 particles 21 nm in diameter, the nanoglue induced interparticle chemical bridging via the condensation of hydroxyl groups on surfaces of TiO2 particles. The efficiency of nanoglue-based DSSCs was improved by approximately 25% compared to non-nanoglue-based DSSCs. This improvement was mainly ascribed to enhanced interparticle connections due to the presence of the 5 nm TiO2 particles in nanoglue.
Indefinite permittivity and negative refraction in natural material: Graphite
Authors: Sun Jingbo , Zhou Ji , Li Bo , Kang Feiyu
Published: March 2011

In this work, we report a nature indefinite permittivity in crystalline graphite that exhibits negative group refraction at ultraviolet region. A hyperbolic equifrequency contour was obtained from ellipsometry data at 254 nm and an all angle negative refraction was verified experimentally. The indefinite permittivity is attributed to extremely strong anisotropy in the crystal structure and the hybrid electronic transitions. This result not only explores a route toward natural negative-index materials, but also holds a promise for ultraviolet hyperlens, which may lead to a breakthrough in nanolithography for the next generation of electronics.