bluuebunny/crossref_metadata_2025 huggingface dataset:
Monte Carlo simulation strategies for computing the wetting properties of fluids at geometrically rough surfaces
Authors: Kumar Vaibhaw , Sridhar Shyam , Errington Jeffrey R.
Published: November 2011

We introduce Monte Carlo simulation methods for determining the wetting properties of model systems at geometrically rough interfaces. The techniques described here enable one to calculate the macroscopic contact angle of a droplet that organizes in one of the three wetting states commonly observed for fluids at geometrically rough surfaces: the Cassie, Wenzel, and impregnation states. We adopt an interface potential approach in which the wetting properties of a system are related to the surface density dependence of the surface excess free energy of a thin liquid film in contact with the substrate. We first describe challenges and inefficiencies encountered when implementing a direct version of this approach to compute the properties of fluids at rough surfaces. Next, we detail a series of convenient thermodynamic paths that enable one to obtain free energy information at relevant surface densities over a wide range of temperatures and substrate strengths in an efficient manner. We then show how this information is assembled to construct complete wetting diagrams at a temperature of interest. The strategy pursued within this work is general and is expected to be applicable to a wide range of molecular systems. To demonstrate the utility of the approach, we present results for a Lennard-Jones fluid in contact with a substrate containing rectangular-shaped grooves characterized by feature sizes of order ten fluid diameters. For this particular fluid-substrate combination, we find that the macroscopic theories of Cassie and Wenzel provide a reasonable description of simulation data.
Jumps of adiabatic invariant at the separatrix of a degenerate saddle point
Authors: Artemyev A. V. , Neishtadt A. I. , Zelenyi L. M.
Published: November 2011

We consider a slow-fast Hamiltonian system with two degrees of freedom. One degree of freedom corresponds to slow variables, and the other one corresponds to fast variables. A characteristic ratio of the rates of change of slow and fast variables is a small parameter κ. For every fixed value of the slow variables, in the phase portrait of the fast variables there are a saddle point and separatrices passing through it. When the slow variables change, phase points may cross the separatrices. The action variable of the fast motion is an adiabatic invariant of the full system as long as a trajectory is far from the separatrices: value of the adiabatic invariant is conserved with an accuracy of order of κ on time intervals of order of 1/κ. A passage through a narrow neighborhood of the separatrices results in a jump of the adiabatic invariant. We consider a case when the saddle point is degenerate. We derive an asymptotic formula for the jump of the adiabatic invariant which turns out to be a value of order of κ3/4 (in the case of a non-degenarate saddle point a similar jump is known to be a value of order of κ). Accumulation of these jumps after many consecutive separatrix crossings leads to the “diffusion” of the adiabatic invariant and chaotic dynamics. We verify the analytical expression for the jump of the adiabatic invariant by numerical simulations. We discuss application of the obtained results to the description of charged particle dynamics in the Earth magnetosphere.
Exciton confinement in homo- and heteroepitaxial ZnO/Zn1 − xMgxO quantum wells with x < 0.1
Authors: Laumer Bernhard , Wassner Thomas A. , Schuster Fabian , Stutzmann Martin , Schörmann Jörg , Rohnke Marcus , Chernikov Alexej , Bornwasser Verena , Koch Martin , Chatterjee Sangam , Eickhoff Martin
Published: November 2011

ZnO/Zn1 − xMgxO single quantum well (SQW) structures with well widths dW between 1.1 nm and 10.4 nm were grown by plasma-assisted molecular beam epitaxy both heteroepitaxially on c-plane sapphire and homoepitaxially on (0001¯)-oriented bulk ZnO. A significantly reduced Mg incorporation in the top barrier related to the generation of stacking faults is observed for heteroepitaxial samples. Exciton localization is observed for both types of samples, while an enhancement of the exciton binding energy compared to bulk ZnO is only found for homoepitaxial SQWs for 2 nm ≤ dW ≤ 4 nm. Consistently, for homoepitaxial samples, the carrier dynamics are mainly governed by radiative recombination and carrier cooling processes at temperatures below 170 K, whereas thermally activated non-radiative recombination dominates in heteroepitaxial samples. The effects of polarization-induced electric fields are concealed for Mg concentrations x < 0.1 due to the reduction of the exciton binding energy, the screening by residual carriers as well as the asymmetric barrier structure in heteroepitaxial wells.
Excitation of electrostatic plasma waves using a dielectric covered metallic electrode
Authors: Kar S. , Mukherjee S.
Published: November 2011

Plasma response to high positive and negative voltage pulses is studied using pulsed capacitive excitation in a uniform and unmagnetized plasma. The positive or negative voltage pulse is applied to a metallic electrode, covered by a dielectric (Kapton) film, immersed in a low pressure argon plasma. The pulse magnitude is much greater than the electron temperature (U0 ≫ kTe/e). Experiments are carried out for different plasma parameters, to find how the plasma perturbations propagate for various applied pulse widths in comparison to ion plasma period ( fi-1). Plasma perturbations are studied by varying the thickness of the dielectric. For positive pulse bias, depending on the dielectric thickness, excitation of solitary electron holes, or solitary ion holes are observed. For negative pulse bias, varying the dielectric thicknesses, only ion rarefaction waves are excited.
Resonance electron attachment and long-lived negative ions of phthalimide and pyromellitic diimide
Authors: Pshenichnyuk Stanislav A. , Vorob'ev Alexander S. , Modelli Alberto
Published: November 2011

Resonance attachment of low energy (0–15 eV) electrons to imide-containing molecules, phthalimide (PTI) and pyromellitic diimide (PMDI), was investigated in the gas-phase by means of Electron Transmission Spectroscopy (ETS) and Dissociative Electron Attachment Spectroscopy (DEAS). Among a variety of low intensity negatively charged fragments formed by DEA, in both compounds the dominant species was found to be a long-lived (μs) parent molecular anion formed at zero energy. In addition, in PMDI long-lived molecular anions were also observed at 0.85 and 2.0 eV. The experimentally evaluated detachment times from the molecular anions as a function of incident electron energy are modeled with a simple computational approach based on the RRKM theory. The occurrence of radiationless transitions to the ground anion state, followed by internal vibrational relaxation, is believed to be a plausible mechanism to explain the exceptionally long lifetime of the PMDI molecular anions formed above zero energy.
Closed-loop phase stabilizing and phase stepping methods for fiber-optic projected-fringe digital interferometry
Authors: Chao Zhang , Fa-Jie Duan
Published: November 2011

Closed-loop active homodyne control can be used to make an interferometer steady against phase fluctuating followed by, for example, temperature gradients. This technology is introduced to stabilize π/2 -rad phase steps in a full-field interferometer. Two beams emitted from a fiber-optic coupler are combined to form an interference fringe pattern on a diffusely reflecting object. Fresnel reflections from the distal fiber ends undergo a double pass in the fibers and interference at the fourth port of the coupler which formed a Michelson interferometer. We suggested two means of ac phase tracking (PTAC) and dc phase tracking (PTDC) to maintain the interference intensity at quadrature by feedback control. Stepping between quadrature positions forces a π/2 -rad phase step. A method based on the ratio of harmonic of the interference signal was proposed to estimate phase step accuracy. A root-mean-square phase stability of 1.5 mrad and phase step accuracy of 2.6 mrad were measured with PTAC and a root-mean-square phase stability of 2 mrad and phase step accuracy of 13.8 mrad were measured with PTDC for the fiber-optic projected-fringe digital interferometry following the same condition. It worked well in two hours without resetting the integrator.
Spin-polarized transport through ZnMnSe/ZnSe/ZnBeSe heterostructures
Authors: Ming Y. , Gong J. , Zhang R. Q.
Published: November 2011

Using the transfer matrix method and Airy function, the spin-dependent tunneling through the ZnMnSe/ZnSe/ZnBeSe structure was investigated theoretically. The electron tunneling determined by the applied bias, external magnetic field, and spin orientations exhibited some interesting and complex features. It was found that the magnetic field could suppress the spin-up current, but enhance the spin-down current. Furthermore the spin-flip of current could be realized by changing the applied bias slightly. Therefore, it can be believed that our structure could behave as a good spin-filter.
Andreev nanoprobe of half-metallic CrO2 films using superconducting cuprate tips
Authors: Turel C. S. , Guilaran I. J. , Xiong P. , Wei J. Y. T.
Published: November 2011

Superconducting tips of YBa2Cu3O7−x were used to perform point-contact Andreev reflection spectroscopy on half-metallic CrO2 thin films. At 4.2 K, strong suppression of the d-wave Andreev reflection characteristics was observed, consistent with the high spin polarization of CrO2. Our technique was validated by comparison with data taken on non-magnetic Au films and with data taken by superconducting Pb tips. The point contacts were estimated to be ≲10 nm in size, attesting to their ballistic and microscopic nature. Our results demonstrate the feasibility of using superconducting cuprate tips as spin-sensitive nanoprobes of ferromagnets.
Composition dependence of magnetoresistance effect and its annealing endurance in tunnel junctions having Mn-Ga electrode with high perpendicular magnetic anisotropy
Authors: Kubota Takahide , Araidai Masaaki , Mizukami Shigemi , Zhang Xianmin , Ma Qinli , Naganuma Hiroshi , Oogane Mikihiko , Ando Yasuo , Tsukada Masaru , Miyazaki Terunobu
Published: November 2011

The composition dependence of the tunnel magnetoresistance (TMR) effect in Mn-Ga/MgO/CoFe magnetic tunnel junctions (MTJs) for Mn54Ga46, Mn62Ga38, and Mn71Ga29 (at. %) electrodes was investigated. An MTJ with a Mn62Ga38 electrode showed a maximum TMR ratio of 23% at 10 K and high annealing endurance up to 375 °C. The bias voltage dependence of the TMR ratio was distinct among MTJs with different Mn-Ga compositions. Here, we discuss this dependence on the basis of the difference in the Δ1 band dispersions for Mn-Ga alloys calculated by first principles.
Note: High capacity digital laser beam steering system
Authors: Hebert D. , Cantu P. , Washington C. , Ajala O. , Feldman M.
Published: November 2011

The combination of liquid crystal cells with polarizing cube beam splitters has been used to direct a beam of light to multiple directions. The polarization at each beam splitter is controlled by applying a signal to a corresponding liquid crystal cell. Ten cascaded stages have deflected a HeNe laser beam to 1024 digitally selectable angles.
Weak-relaxor behaviour in Bi/Yb-doped KNbO3 ceramics
Authors: Luisman Luke , Feteira Antonio , Reichmann Klaus
Published: November 2011

Weak-relaxor behaviour was observed in K1−xBixNb1−xYbxO3 ceramics with x = 0.20 and x = 0.30. According to x-ray diffraction analysis, the crystal structure of these ceramics can be described by the cubic centrosymmetric Pm3¯m space group; however Raman spectroscopy reveals both the occurrence of local lattice distortions and the disruption of the long-range ferroelectric order. The local lattice strain caused by the larger Yb3+ combined with the presence of Bi3+, which lone-pair of electrons induces further local distortions, gives rise to polar nanoregions (PNRs). Nevertheless, the interaction between the PNRs appears weak and proper relaxor behaviour does not develop.
Room temperature magnetoelectric memory cell using stress-mediated magnetoelastic switching in nanostructured multilayers
Authors: Tiercelin Nicolas , Dusch Yannick , Klimov Alexey , Giordano Stefano , Preobrazhensky Vladimir , Pernod Philippe
Published: November 2011

We present here the demonstration of magnetoelectric switching of magnetization between two stable positions defined by a combination of anisotropy and magnetic field. A magnetoelastic nanostructured multilayer with the required uni-axial characteristic was deposited onto a commercial piezoelectric actuator. Thanks to the inverse magnetostrictive effect, the effective anisotropy of the magnetic element is controlled by the applied voltage and used to switch magnetization from one state to the other. Both vibrating sample magnetometer and magneto-optical Kerr effect measurements have been performed and demonstrate the magnetoelectric switching.
Biomimetic broadband antireflection gratings on solar-grade multicrystalline silicon wafers
Authors: Phillips Blayne M. , Jiang Peng , Jiang Bin
Published: November 2011

We report a simple and scalable bottom-up technique for fabricating broadband antireflection gratings on solar-grade multicrystalline silicon (mc-Si) wafers. A Langmuir-Blodgett process is developed to assemble close-packed silica microspheres on rough mc-Si substrates. Subwavelength moth-eye pillars can then be patterned on mc-Si by using the silica microspheres as structural template. Hemispherical reflectance measurements show that the resulting mc-Si gratings exhibit near zero reflection for a wide range of wavelengths. Both experimental results and theoretical prediction using a rigorous coupled-wave analysis model show that close-packed moth-eye arrays exhibit better antireflection performance than non-close-packed arrays due to a smoother refractive index gradient.
Extreme ultraviolet source at 6.7 nm based on a low-density plasma
Authors: Higashiguchi Takeshi , Otsuka Takamitsu , Yugami Noboru , Jiang Weihua , Endo Akira , Li Bowen , Kilbane Deirdre , Dunne Padraig , O’Sullivan Gerry
Published: November 2011

We demonstrate an efficient extreme ultraviolet (EUV) source for operation at λ = 6.7 nm by optimizing the optical thickness of gadolinium (Gd) plasmas. Using low initial density Gd targets and dual laser pulse irradiation, we observed a maximum EUV conversion efficiency (CE) of 0.54% for 0.6% bandwidth (BW) (1.8% for 2% BW), which is 1.6 times larger than the 0.33% (0.6% BW) CE produced from a solid density target. Enhancement of the EUV CE by use of a low-density plasma is attributed to the reduction of self-absorption effects.
Measurement of backscattered 100 keV electrons on a solid substrate
Authors: Czaplewski David A. , Ocola Leonidas E.
Published: November 2011

We have measured the intensity of backscattered 100 keV electrons on a silicon substrate as a function of distance up to 50 μm from the source. The intensity of backscattered electrons was determined by measuring the thickness changes in pre-exposed, isolated 100 nm crosses in a negative resist using atomic force microscopy. The electron backscattered range was measured to be 31.08 ± 0.30 μm and showed deviation from Gaussian behavior for radii larger than 30 μm. This method produces an accurate measurement of the backscattered range because it is process independent and covers a large data range.
Does workforce regulation have the intended effect? The case of Chinese medicine practitioner registration
Authors: Lin Vivian , Gillick Debra
Published: November 2011

The Chinese Medicine Registration Act was passed through Victorian parliament in 2000, based on policy research that suggested the need for statutory registration as a means for protecting public health and safety. This paper reports on the implementation and the effect of this policy. By examining registration, complaints and prosecution data from the Chinese Medicine Registration Board as well as comparing the complaints data between 2003 and 2007 across all Victorian registration boards, this paper considers the extent to which the policy research and the policy intent were justified. Based on the experience of the Chinese Medicine Registration Board, the paper points to issues that should be further considered as Chinese medicine moves into the national registration scheme in July 2012.

What is known about the topic?
Australian Federal, State and Territory governments’ criteria for regulation of health professions are aimed at protecting public health and safety. As such, the extent to which the profession poses a risk to the public is a key consideration for statutory registration. Chinese medicine practitioners have been registered in Victoria since 2002 based on theoretical analysis of the Governments’ criteria, which suggested Chinese medicine to be more risky than some of the currently registered professions. What is not known, however, is whether the research undertaken before policy adoption was predictive of the outcomes following registration.

What does this paper add?
Reviewing the number and sources of complaints made to the Chinese Medicine Registration Board as well as registration and prosecution data, the paper demonstrates that the policy objective of protecting public health and safety was warranted, and that there is a need for similar policy beyond Victoria. Using complaints handled by boards as a proxy measure for risk, comparative analysis of data from Victorian health professions registration boards between 2003 and 2007 shows that Chinese medicine is a high risk profession.

What are the implications for practitioners?
With Chinese medicine practitioners coming under the national registration scheme in July 2012, some of the difficulties associated with federalism will be overcome. Other aspects of the Victorian experience will be useful in informing implementation and likely effect of the national scheme. However, the model for health professional regulation remains essentially reactive. Although the management of complaints is an essential aspect of protecting public health and safety, ongoing review of complaints data should point to more proactive efforts to prevent their occurrence.
Inter-simple sequence repeat (ISSR)-based diversity assessment among faba bean genotypes
Authors: Alghamdi Salem S. , Al-Faifi Sulieman A. , Migdadi Hussein M. , Ammar Megahed H. , Siddique K. H. M.
Published: November 2011

Thirty-four faba bean (Vicia faba L.) including local and exotic materials were subjected to molecular diversity assessment using 12 inter-simple sequence repeat primers. The molecular data showed unambiguous and qualitative (present or absent) fragments that gave repeatable patterns were considered for the analysis. The 12 selected primers produced a total of 71 fragments (loci), all of which were polymorphic using the 34 collected faba genotypes. The results of clustering Nei’s genetic distance using the unweighted pair group method with arithmetic average algorithm at the 0.52 dissimilarity separated genotypes to six main clusters with many subclusters. The local genotypes were distributed to most of all clusters. Genotypes collected from Egypt and King Saud University was grouped together in two clusters, ICARDA’s genotypes in two clusters and two genotypes (H8, local determent genotype and 987–255–95 line) formed a single cluster. The high number of subclusters formed in this study indicated that there is a high genetic variability related to collection sites and it should be utilised in faba bean improvement.
Post head-emergence frost resistance of barley genotypes in the northern grain region of Australia
Authors: Frederiks T. M. , Christopher J. T. , Fletcher S. E. H. , Borrell A. K.
Published: November 2011

Post head-emergence frost causes substantial losses for Australian barley producers. Varieties with improved resistance would have a significant positive impact on Australian cropping enterprises. Five barley genotypes previously tested for reproductive frost resistance in southern Australia were tested, post head-emergence, in the northern grain region of Australia and compared with the typical northern control cultivars, Gilbert and Kaputar. All tested genotypes suffered severe damage to whole heads and stems at plant minimum temperatures less than −8°C. In 2003, 2004 and 2005, frost events reaching a plant minimum temperature of ~−6.5°C did not result in the complete loss of grain yield. Rather, partial seed set was observed. The control genotype, Gilbert, exhibited seed set that was greater than or equal to that of any genotype in each year, as did Kaputar when tested in 2005. Thus, Gilbert and Kaputar were at least as resistant as any tested genotype. This contrasts with trial results from the southern grain region where Gilbert was reported to be less resistant than Franklin, Amagi Nijo and Haruna Nijo. Hence, rankings for post head-emergence frost damage in the northern grain region differ from those previously reported. These results indicate that Franklin, Amagi Nijo and Haruna Nijo are not likely to provide useful sources of frost resistance or markers to develop improved varieties for the northern grain region of Australia.
Genetic control of aluminium tolerance in pigeonpea (Cajanus cajan L.)
Authors: Singh D. , Raje R. S. , Choudhary A. K.
Published: November 2011

Aluminium toxicity is a major factor limiting plant growth in acid soil and more adequate genetic tolerance is needed to improve pigeonpea adaptation and production in affected areas. To study the inheritance, tolerant lines IPA7-10, T-7 were crossed with sensitive lines Pusa 9 and Bahar. The parents, F1, F2 and F3 generations were grown in a nutrient solution containing 30 ppm aluminium for hematoxylin staining and root re-growth measure and classified for tolerance by staining of root tips and root re-growth. The segregation ratios obtained for aluminium tolerance in the F2 and F3 generations were 15 : 1 and 7 : 8 : 1, respectively. These results indicated that aluminium tolerance is controlled by two dominant genes.
Condoms and US college-aged men and women: briefly assessing attitudes toward condoms and general condom use behaviours
Authors: Hill Brandon J. , Amick Erick E. , Sanders Stephanie A.
Published: November 2011

Background
The purpose of this study was to develop an abbreviated reliable tool for assessing the attitudes US college-aged men and women have about condoms and condom use. Method: An online questionnaire was constructed and completed by 674 participants incorporating modified items from the Attitudes Towards Condom Scale (1984) and the Multidimensional Condom Attitude Scale (1994), with the addition of gender-neutral worded and condom positive or erotic items. Results: The original 40 items were reduced to 18 Likert-type items comprising the Brief Condom Attitude Scale (BCAS). Gender comparisons on a subset of 584 self-identified heterosexual participants indicated that women were significantly more likely to consider condoms as less protective, while men were significantly more likely to consider condoms as more interruptive. Additional analyses examining partnership indicated that monogamous participants were significantly more likely to view condoms as less interruptive, more erotic and less negative than non-monogamous participants. Conclusions: The BCAS appears to be a reliable measure for assessing US college-aged individuals’ attitudes about condoms.
Increase in HIV diagnoses among men who have sex with men in New Zealand from a stable low period
Authors: Saxton Peter J. W. , Dickson Nigel P. , McAllister Susan M. , Sharples Katrina , Hughes Anthony J.
Published: November 2011

Objectives
To describe trends in HIV diagnoses among men who have sex with men (MSM) in New Zealand 1996–2008, and to identify characteristics associated with HIV diagnoses in the resurgent phase. Methods: Data collected through routine surveillance of HIV infection, where the mode of transmission included homosexual contact, were analysed over the period 1996–2008. Results: Annual HIV diagnoses were low during 1996–2000, rose sharply between 2001 and 2005, and remained at an elevated plateau between 2006 and 2008. Over a quarter were attributed to HIV infection acquired overseas (28.6%). Trends in diagnoses of locally acquired HIV infection closely mirrored the trend of three diagnosis phases. Increases in locally acquired HIV occurred among virtually all characteristics of MSM. However, compared with MSM diagnosed in the low phase 1996–2000, individuals diagnosed in the resurgent phase 2001–05 were more likely to be aged 30–39, to have tested HIV-negative within the previous 2 years, to live in the Northern region encompassing Auckland, and to be of non-European ethnicity. The per capita HIV diagnosis rate among MSM was lowest in 1997, at 22.0 per million males aged 15–64, and highest in 2005 at 66.7 per million. Conclusion: The increase in HIV diagnoses among MSM in New Zealand was primarily due to an increase in locally acquired HIV infection, which disproportionately affected some groups of MSM. Factors driving this change in local epidemic conditions need to be identified. The rate of new HIV diagnoses among MSM remains low by international standards.
HIV-associated kidney disease in the context of an aging population
Authors: Naftalin Claire , Nathan Bavithra , Hamzah Lisa , Post Frank A.
Published: November 2011

Acute renal failure and chronic kidney disease are more common in HIV-infected patients compared with the general population. Several studies have shown age to be a risk factor for HIV-associated kidney disease. The improved life expectancy of HIV-infected patients as a result of widespread use of antiretroviral therapy has resulted in progressive aging of HIV cohorts in the developed world, and an increased burden of cardiovascular and kidney disease. Consequently, HIV care increasingly needs to incorporate strategies to detect and manage these non-infectious co-morbidities.
Sexually transmissible infections in aging HIV populations
Authors: Poynten I. Mary , Templeton David J. , Grulich Andrew E.
Published: November 2011

There is limited published research on sexually transmissible infections (STI) among aging HIV populations. The available literature on sexual behaviour and STI among older people with HIV is reviewed here and contrasted with data from older individuals in the general population and from older populations at high risk of HIV. A sizeable minority of older people with HIV continue to engage in higher risk sexual behaviour and thus remain at high risk of STI. There is no clear evidence of a consistent effect of older age on STI rates, clinical presentation or clinical course among HIV-infected populations, although gay men with HIV aged in their 40s or older seem to be at higher risk than younger men of acquiring several STI, including syphilis and lymphogranuloma venereum. STI risks in older people living with HIV need to be regularly assessed. Higher risk sexual behaviour and disproportionately higher rates of STI indicate that regardless of age, a thorough STI assessment should be regularly undertaken for all HIV-positive gay men as part of their routine HIV care.
Sexual function and dysfunction in older HIV-positive individuals
Authors: Russell Darren B.
Published: November 2011

With many parts of the world seeing an aging cohort of people living with HIV (PLHIV), it is becoming clear that some organ systems in these individuals are at a greater risk of disease. There are effects on sexual functioning in aging PLHIV, with many studies finding higher levels of sexual dysfunction in HIV-positive individuals compared with those who are HIV-negative. HIV itself, along with antiretroviral agents, may cause dysfunction. Treatment involves making an assessment of the dysfunction and using the usual methods available, although treatment may be complicated by hormonal deficiencies in HIV-positive individuals, along with the effects of antiretroviral therapy, and drug interactions involving such medications. Furthermore, the issue of HIV transmission needs to be addressed in those seeking treatment for sexual dysfunction.
Redefining the relevance of established cancer cell lines to the study of mechanisms of clinical anti-cancer drug resistance
Authors: Gillet Jean-Pierre , Calcagno Anna Maria , Varma Sudhir , Marino Miguel , Green Lisa J. , Vora Meena I. , Patel Chirayu , Orina Josiah N. , Eliseeva Tatiana A. , Singal Vineet , Padmanabhan Raji , Davidson Ben , Ganapathi Ram , Sood Anil K. , Rueda Bo R. , Ambudkar Suresh V. , Gottesman Michael M.
Published: November 2011

Although in vitro models have been a cornerstone of anti-cancer drug development, their direct applicability to clinical cancer research has been uncertain. Using a state-of-the-art Taqman-based quantitative RT-PCR assay, we investigated the multidrug resistance (MDR) transcriptome of six cancer types, in established cancer cell lines (grown in monolayer, 3D scaffold, or in xenograft) and clinical samples, either containing >75% tumor cells or microdissected. The MDR transcriptome was determined a priori based on an extensive curation of the literature published during the last three decades, which led to the enumeration of 380 genes. No correlation was found between clinical samples and established cancer cell lines. As expected, we found up-regulation of genes that would facilitate survival across all cultured cancer cell lines evaluated. More troubling, however, were data showing that all of the cell lines, grown either in vitro or in vivo, bear more resemblance to each other, regardless of the tissue of origin, than to the clinical samples they are supposed to model. Although cultured cells can be used to study many aspects of cancer biology and response of cells to drugs, this study emphasizes the necessity for new in vitro cancer models and the use of primary tumor models in which gene expression can be manipulated and small molecules tested in a setting that more closely mimics the in vivo cancer microenvironment so as to avoid radical changes in gene expression profiles brought on by extended periods of cell culture.
𝑅-equivalence on low degree complete intersections
Authors: Pirutka Alena
Published: November 2011

Let

k
k

be a function field in one variable over

C

\mathbb C

or the field

C

(
(
t
)
)

\mathbb C((t))

. Let

X
X

be a

k
k

-rationally simply connected variety defined over

k
k

. In this paper we show that

R
R

-equivalence on rational points of

X
X

is trivial and that the Chow group of zero-cycles of degree zero

A
0

(
X
)

A_0(X)

is zero. In particular, this holds for a smooth complete intersection of

r
r

hypersurfaces in

P

k
n

\mathbb P^n_k

of respective degrees

d
1

,
…
,

d
r

d_1,\ldots ,d_r

with

∑

i
=
1

r

d
i
2

≤
n
+
1

\sum \limits _{i=1}^{r}d_i^2\leq n+1

.
Plasticity of preferred body temperatures as means of coping with climate change?
Authors: Gvoždík Lumír
Published: November 2011

Thermoregulatory behaviour represents an important component of ectotherm non-genetic adaptive capacity that mitigates the impact of ongoing climate change. The buffering role of behavioural thermoregulation has been attributed solely to the ability to maintain near optimal body temperature for sufficiently extended periods under altered thermal conditions. The widespread occurrence of plastic modification of target temperatures that an ectotherm aims to achieve (preferred body temperatures) has been largely overlooked. I argue that plasticity of target temperatures may significantly contribute to an ectotherm's adaptive capacity. Its contribution to population persistence depends on both the effectiveness of acute thermoregulatory adjustments (reactivity) in buffering selection pressures in a changing thermal environment, and the total costs of thermoregulation (i.e. reactivity and plasticity) in a given environment. The direction and magnitude of plastic shifts in preferred body temperatures can be incorporated into mechanistic models, to improve predictions of the impact of global climate change on ectotherm populations.
A theory of biological relativity: no privileged level of causation
Authors: Noble Denis
Published: November 2011

Must higher level biological processes always be derivable from lower level data and mechanisms, as assumed by the idea that an organism is completely defined by its genome? Or are higher level properties necessarily also causes of lower level behaviour, involving actions and interactions both ways? This article uses modelling of the heart, and its experimental basis, to show that downward causation is necessary and that this form of causation can be represented as the influences of initial and boundary conditions on the solutions of the differential equations used to represent the lower level processes. These insights are then generalized.A priori, there is no privileged level of causation. The relations between this form of ‘biological relativity’ and forms of relativity in physics are discussed. Biological relativity can be seen as an extension of the relativity principle by avoiding the assumption that there is a privileged scale at which biological functions are determined.
Predicting the effect of climate change on African trypanosomiasis: integrating epidemiology with parasite and vector biology
Authors: Moore Sean , Shrestha Sourya , Tomlinson Kyle W. , Vuong Holly
Published: November 2011

Climate warming over the next century is expected to have a large impact on the interactions between pathogens and their animal and human hosts. Vector-borne diseases are particularly sensitive to warming because temperature changes can alter vector development rates, shift their geographical distribution and alter transmission dynamics. For this reason, African trypanosomiasis (sleeping sickness), a vector-borne disease of humans and animals, was recently identified as one of the 12 infectious diseases likely to spread owing to climate change. We combine a variety of direct effects of temperature on vector ecology, vector biology and vector–parasite interactions via a disease transmission model and extrapolate the potential compounding effects of projected warming on the epidemiology of African trypanosomiasis. The model predicts that epidemics can occur when mean temperatures are between 20.7°C and 26.1°C. Our model does not predict a large-range expansion, but rather a large shift of up to 60 per cent in the geographical extent of the range. The model also predicts that 46–77 million additional people may be at risk of exposure by 2090. Future research could expand our analysis to include other environmental factors that influence tsetse populations and disease transmission such as humidity, as well as changes to human, livestock and wildlife distributions. The modelling approach presented here provides a framework for using the climate-sensitive aspects of vector and pathogen biology to predict changes in disease prevalence and risk owing to climate change.
Sexual conflict over parental investment in repeated bouts: negotiation reduces overall care
Authors: Lessells C. M. , McNamara John M.
Published: November 2011

Understanding the evolution of parental care is complicated by the occurrence of evolutionary conflicts of interest within the family, variation in the quality and state of family members, and repeated bouts of investment in a family of offspring. As a result, family members are expected to negotiate over care. We present a model for the resolution of sexual conflict in which parents negotiate over repeated bouts of care. Negotiation is mediated by parents deciding at the start of each bout how much care to give on the basis of the state (mass) of offspring, which reflects the amount of care previously received. The evolutionarily stable pattern of care depends on whether the parents care together for the whole family, or each cares alone for part of the divided family. When they care together, they provide less care in the first bout, more in the last bout, and less care overall, resulting in lower parental and offspring fitness. Our results emphasize that negotiation over parental care may occur as a means of avoiding exploitation owing to sexual conflict, even in the absence of variation in the quality of either sex of parent, and lead to a reduction in fitness.
Novel methods reveal shifts in migration phenology of barn swallows in South Africa
Authors: Altwegg Res , Broms Kristin , Erni Birgit , Barnard Phoebe , Midgley Guy F. , Underhill Les G.
Published: November 2011

Many migratory bird species, including the barn swallow (
Hirundo rustica
), have advanced their arrival date at Northern Hemisphere breeding grounds, showing a clear biotic response to recent climate change. Earlier arrival helps maintain their synchrony with earlier springs, but little is known about the associated changes in phenology at their non-breeding grounds. Here, we examine the phenology of barn swallows in South Africa, where a large proportion of the northern European breeding population spends its non-breeding season. Using novel analytical methods based on bird atlas data, we show that swallows first arrive in the northern parts of the country and gradually appear further south. On their north-bound journey, they leave South Africa rapidly, resulting in mean stopover durations of 140 days in the south and 180 days in the north. We found that swallows are now leaving northern parts of South Africa 8 days earlier than they did 20 years ago, and so shortened their stay in areas where they previously stayed the longest. By contrast, they did not shorten their stopover in other parts of South Africa, leading to a more synchronized departure across the country. Departure was related to environmental variability, measured through the Southern Oscillation Index. Our results suggest that these birds gain their extended breeding season in Europe partly by leaving South Africa earlier, and thus add to scarce evidence for phenology shifts in the Southern Hemisphere.
Skimming the surface with Burgess Shale arthropod locomotion
Authors: Minter Nicholas J. , Mángano M. Gabriela , Caron Jean-Bernard
Published: November 2011

The first arthropod trackways are described from the Middle Cambrian Burgess Shale Formation of Canada. Trace fossils, including trackways, provide a rich source of biological and ecological information, including direct evidence of behaviour not commonly available from body fossils alone. The discovery of large arthropod trackways is unique for Burgess Shale-type deposits. Trackway dimensions and the requisite number of limbs are matched with the body plan of a tegopeltid arthropod.Tegopelte, one of the rarest Burgess Shale animals, is over twice the size of all other benthic arthropods known from this locality, and only its sister taxon,Saperion, from the Lower Cambrian Chengjiang biota of China, approaches a similar size. Biomechanical trackway analysis demonstrates that tegopeltids were capable of rapidly skimming across the seafloor and, in conjunction with the identification of gut diverticulae inTegopelte, supports previous hypotheses on the locomotory capabilities and carnivorous mode of life of such arthropods. The trackways occur in the oldest part (Kicking Horse Shale Member) of the Burgess Shale Formation, which is also known for its scarce assemblage of soft-bodied organisms, and indicate at least intermittent oxygenated bottom waters and low sedimentation rates.
Subcutaneous Adipose Tissue from Obese and Lean Adults Does Not Release HepcidinIn Vivo
Authors: Tussing-Humphreys Lisa , Frayn Keith N. , Smith Steven R. , Westerman Mark , Dennis A. Louise , Nemeth Elizabeta , Thomson Jessica , Pusatcioglu Cenk
Published: November 2011

Hepcidin is the main regulator of systemic iron homeostasis and is primarily produced by the liver but is also expressed, at the mRNA-level, in periphery tissues including the subcutaneous and visceral adipose tissue. Obesity is associated with elevated hepcidin concentrations and iron depletion suggesting that the exaggerated fat mass in obesity could contribute significantly to circulating hepcidin levels consequently altering iron homeostasis. The objective of this study was to determine if abdominal subcutaneous adipose tissue (AbScAT) releases hepcidinin vivoand if release is modified by obesity. Arterio-venous differences in concentrations of hepcidin were measured across AbScAT in 9 obese and 9 lean adults. Overall (n=18), mean plasma hepcidin concentrations were significantly higher in arterialized compared to AbScAT venous samples [mean difference (arterialized-AbScAT venous plasma hepcidin) =4.9±9.6 ng/mL,P=0.04]. Net regional release was not calculated because mean venous plasma hepcidin concentrations were lower than mean arterialized concentrations indicating no net release. Significant correlations between AbScAT venous and arterialized plasma hepcidin concentrations with anthropometric variables were not observed. Findings from this vein drainage study suggest there is no net release of hepcidin from the AbScAT depot and thereby no ability to signal systemically, even in obesity.
A randomised trial comparing the laryngeal mask airway Supreme™ with the laryngeal mask airway Unique™ in children*
Authors: Jagannathan N. , Sohn L. E. , Sawardekar A. , Chang E. , Langen K. E. , Anderson K.
Published: November 2011

We conducted a randomised controlled trial comparing the laryngeal mask airway Supreme™ with the laryngeal mask airway Unique™ in children. Fifty children presenting for elective surgery were randomly assigned to receive either the laryngeal mask airway Supreme or laryngeal mask airway Unique. The outcomes measured were airway leak pressure, ease and time for insertion, insertion success rate, fibreoptic examination, incidence of gastric insufflation, ease of gastric tube placement through the laryngeal mask airway Supreme, quality of airway during anaesthetic maintenance and complications. Median (IQR [range]) time to successful device placement was shorter with the laryngeal mask airway Unique, 14.5 [13.5–16.3 (10.0–23.6)] s than with the laryngeal mask airway Supreme, 17.4 [14.8–19.8 (11.5–29.2)] s; p = 0.007. Median (IQR [range]) airway leak pressures for the laryngeal mask airway Supreme and laryngeal mask airway Unique were 20 [16–21 (12–22)] cmH2O and 15 [14–18 (10–24)] cmH2O, respectively (p = 0.001). The incidence of gastric insufflation was lower with the laryngeal mask airway Supreme (zero vs six patients), p = 0.01. In conclusion, the laryngeal mask airway Supreme performed as well as the laryngeal mask airway Unique and is a useful alternative for airway maintenance, particularly in children who require evacuation of gastric contents during anaesthesia.
Feasibility of an obesity intervention for paediatric primary care targeting parenting and children: Helping HAND
Authors: O'Connor T. M. , Hilmers A. , Watson K. , Baranowski T. , Giardino A. P.
Published: November 2011

Background  The primary care setting offers the opportunity to reach children and parents to encourage healthy lifestyle behaviours, and improve weight status among children.

Objective  Test the feasibility of Helping HAND (Healthy Activity and Nutrition Directions), an obesity intervention for 5‐ to 8‐year‐old children in primary care clinics.

Methods  A randomized controlled pilot study of Helping HAND, a 6‐month intervention, targeted children with body mass index 85–99%tile and their parents. Intervention group attended monthly sessions and self‐selected child behaviours and parenting practices to change. Control group received regular paediatric care and was wait‐listed for Helping HAND. Session completion, participant satisfaction, child anthropometrics, dietary intake, physical activity, TV viewing and behaviour‐specific parenting practices were measured pre and post intervention.

Results  Forty parent–child dyads enrolled: 82.5% were Hispanic, 80% had a girl and 65% reported income ≤$30 000/year. There was 20% attrition from Helping HAND (attended <4/6 sessions). Families self‐selected 4.35 (SD 1.75) behaviours to target during the 6‐month programme and each of the seven behaviours was selected by 45–80% of the families. There were no between group differences in the child's body mass index z‐score, dietary intake or physical activity post intervention. Intervention group viewed 14.9 (SE 2.3) h/week of TV post intervention versus control group 23.3 (SE 2.4) h/week (P < 0.05).

Conclusion  Helping HAND is feasible, due to low attrition, good programme attendance, and clinically relevant improvements in some child and parenting behaviours.
Effect of intracanal dentine wettability on human dental pulp cell attachment
Authors: Huang X. , Zhang J. , Huang C. , Wang Y. , Pei D.
Published: November 2011

Huang X, Zhang J, Huang C, Wang Y, Pei D. Effect of intracanal dentine wettability on human dental pulp cell attachment. International Endodontic Journal, 45, 346–353, 2012.

Aim  To evaluate the effect of intracanal dentine wettability on human dental pulp cell (HDPC) attachment after application of endodontic irrigants.

Methodology  Twenty extracted human premolar teeth with straight canals were sectioned at the apical and coronal thirds of each root, and the remaining mid‐root portions were bisected longitudinally. After polishing, the specimens were divided into two groups for wettability and cell attachment measurements, respectively. The intracanal surface wettability was assessed by atomic force microscopy after a rinse of H2O (control), 5.25% sodium hypochlorite (NaOCl), 17% ethylenediaminetetraacetic acid (EDTA) and MTAD (n = 5). Additionally, HDPCs were seeded onto the irrigated root canal dentine and the cell attachment was evaluated by calcein‐CAM and propidium iodide (PI) dying under fluorescence microscope (n = 5). Data were analysed by means of one‐way anova and LSD test.

Results  Compared with the control group, 5.25% NaOCl, 17% EDTA and MTAD treatment significantly increased surface wettability (P < 0.001). The rank order of adhesion force was MTAD >17% EDTA >5.25% NaOCl > H2O. The highest average numbers of viable HDPCs were observed on the root canals irrigated with MTAD, followed by the 17% EDTA group (P < 0.001), and the lowest average numbers of viable cells were detected in the 5.25% NaOCl and H2O groups.

Conclusions  Surface wettability was affected by the irrigants. Increasing in wettability produced higher levels of HDPC attachment to irrigated dentine.
Advantages of immunoglobulin Y for the detection of Staphylococcal enterotoxin A in a double‐antibody sandwich enzyme‐linked immunosorbent assay
Authors: Mizutani Noriko , Sugita‐Konishi Yoshiko , Omoe Katsuhiko , Shinagawa Kunihiro , Kawakami Hiroshi , Kanno Shinji , Sugiyama Kei‐ichi , Kamata Yoichi
Published: November 2011

To determine the amounts of staphylococcal enterotoxin A (SEA), a novel and sensitive enzyme‐linked immunosorbent assay (ELISA) was developed. Protein A, which is produced by Staphylococcus aureus, interferes with the reaction between SEA and anti‐SEA immunoglobulin G (IgG), resulting in a false‐positive reaction. Chicken IgY was introduced as a capture antibody in the sandwich ELISA system, as IgY binds less efficiently to protein A. When the anti‐SEA IgG antibody was used as the capture and detection antibodies (IgG‐IgG ELISA), the background levels of protein A increased, thus resulting in a false‐positive reaction. A 0.01 ng mL−1 concentration of protein A significantly increased the absorbance value of the blank wells. When the anti‐SEA IgY antibody was used as the capture antibody, 1000 ng mL−1 of protein A did not affect the absorbance value. The ELISA system using anti‐SEA IgY as a capture antibody and anti‐SEA IgG as a detection antibody (IgY‐IgG ELISA) showed a detection limit of <0.25 ng mL−1 and a creditability of R2 = 0.98. These findings demonstrate the advantage of chicken IgY for the detection of SEA by means of double‐antibody sandwich ELISA.