bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of transient wave propagation in an arbitrary frequency‐dispersive media using the associated laguerre functions in the FDTD‐MOD method
Authors: Jung Baek Ho , Mei Zicong , Sarkar Tapan Kumar , Salazar‐Palma Magdalena
Published: February 2012

In this work, we present a marching‐on‐in‐degree (MOD) method in a finite difference time‐domain (FDTD) framework for analyzing transient electromagnetic responses in a general dispersive media.The two issues related to the finite difference approximation of the time derivatives and the time‐consuming convolution operations are handled analytically using the properties of the associated Laguerre functions. The basic idea here is that we fit the transient nature of the fields, the flux densities, the permittivity and the permeability with a finite sum of orthogonal associated Laguerre functions. Through this novel approach, not only the time variable can be decoupled analytically from the temporal variations but also the final computational form of the equations is transformed from FDTD to a FD formulation through a Galerkin testing. We also propose a second MOD formulation based on the Helmholtz wave equation. Representative numerical examples are presented for transient wave propagation in general Debye, Drude, or a Lorentz dispersive medium. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:925–930, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26696
A low‐power 5‐GHz CMOS RF receiver for WLAN applications
Authors: Cha Minyeon , Kwon Ickjin
Published: February 2012

A low‐power 5‐GHz IEEE 802.11a CMOS RF receiver for wireless local area network is designed.For low‐power dissipation, a dual conversion current‐driven passive mixer is used in an RF front‐end. An optimum allocation of alternated low‐pass filters and amplifiers in a baseband analog chain is also performed. The receiver is fabricated in 0.13 μm 1‐poly 6‐metal CMOS technology. The fully integrated receiver achieves 90.5 dB maximum gain, 7.1 dB noise figure, and −20 dBm input‐referred third‐order intercept point. The chip area is 3.25 mm2 and it consumes a power of 40.8 mW from a supply voltage of 1.2 V. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:842–847, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26700
High efficiency power combining technique for distributed amplifier of different stages
Authors: Mung Steve W. Y. , Hung Kwok Man
Published: February 2012

A high efficiency power combining technique based on distributed amplifier's (DA) topology is proposed to allow efficient distributed combining of FETs' output power without the use of multiway power combiners. The proposed topology uses a quarter‐wave short‐circuit stub or open circuit to replace the drain line lossy dummy load. This topology is able to achieve power equalization among the FETs at microwave frequencies. This design method ensures that optimum loadlines are achieved for all FETs, and the efficiency obtained is comparable to a conventional single‐transistor class‐A power amplifier using the same FET type. Different stages of DA have different optimum loadline resistances for power combining. This optimum characteristic resistance of the drain output transmission line presented here obtains the power‐matched condition for all FETs. It is demonstrated at 2 GHz with 1‐stage, 2‐stage, and 3‐stage DAs. Experimental results show that the power‐added efficiency of these three DAs is greater than 35% at the 1‐dB gain compression point (P1dB). The 3‐stage DA demonstrates an output power of 27.4 dBm at P1dB with power combining efficiency around 90%. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1056–1059, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26703
Analytical solution for the design of planar electromagnetic bandgap structures with spurious‐free frequency response
Authors: Arnedo Israel , Chudzik Magdalena , Schwartz Joshua D. , Arregui Ivan , Lujambio Aintzane , Teberio Fernando , Benito David , Laso Miguel Ángel G. , Plant David V. , Azaña Jose , Lopetegi Txema
Published: February 2012

In this article, an analytical solution is obtained for the design of electromagnetic bandgap (EBG) structures that feature a single stopband without the spurious rejected bands present in the conventional EBG devices at the harmonics of the design frequency.The proposed technique is applied for the design of microwave filters intended for broadband applications, where closed formulas are found both in two‐port lines and in four‐port coupled lines obtaining very good results. The implementation of the EBG structure in coupled lines allows for the redirection of the reflected signal to the coupled port producing a device with input port matched at all frequencies. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:956–960, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26709
BIAS‐free analog predistorters with L‐TYPE attenuator for RF power amplifiers
Authors: Jhang Jyun‐Yuan , Hsue Thomas , Jang Sheng‐Lyang
Published: February 2012

Parallel forward‐reverse Schottky‐diode paths and a L‐type attenuator form a bias‐free predistorter that effectively reduces the intermodulation distortion of an RF power amplifier.The predistorter exhibits a constant insertion loss at the low input power and its insertion loss decreases when the input power increases. The resistor in the L‐type attenuator serves as the transmission path when the input power is small. When the input power is large, on the other hand, the diode paths are activated to serve as the linearization vehicle for the predistorter. An improvement of extended operating power level up to 5 dB with the limit of −30 dBm adjacent‐channel leakage power is obtained for a 5‐watt amplifier at 1.9 GHz. Measured results are presented to illustrate the effectiveness of the predistorter. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:920–923, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26712
A complementary cross‐coupled quadrature VCO using ring‐inductor coupling method
Authors: Jang Sheng‐Lyang , Lin San‐Sheng , Chang Chia‐Wei , Hsu Shih‐Hsiang
Published: February 2012

A high‐performance quadrature voltage‐controlled oscillator (QVCO) with ring inductor is studied. The QVCO uses a closed‐loop ring inductor and is composed of two complementary negative transconductance cells to replenish the energy loss due to the resistive LC resonator and is implemented in a standard TSMC 90 nm 1P9M CMOS technology. This QVCO operates between 7.05 and 8.15 GHz. The measured phase noise of the VCO operating at 8.15 GHz is −119.98 dBc/Hz at 1‐MHz offset while the QVCO draws 4.2 mA and 3.57 mW consumption from a supply voltage of 0.85 V. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:839–842, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26714
Simple CAD formula for the microstrip line on L‐SIAD
Authors: Tang Wanchun , Wang Xiaoke , Liu Xiaoming , Chow Y.Leonard
Published: February 2012

This article presents a simple CAD formula for the microstrip line on localized substrate integrated artificial dielectric (L‐SIAD) by synthetic asymptote. For L‐SIAD, there is a metal post array embedded in the substrate and connected to the bottom ground plane. All the metal posts are right under (but not connected to) the microstrip line. The simple CAD formula is accurate with average error less than 2% compared with numerical results, and gives good physical insight. Finally, this formula is applied to the design of an L‐SIAD microstrip line. The simulations and measurements show good agreements. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:856–858, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26720
Backward wave mode interaction impedance at THz frequencies for corrugated waveguide
Authors: Mineo Mauro , Paoloni Claudio
Published: February 2012

A novel analytical expression to compute the interaction impedance of corrugated rectangular waveguide slow‐wave structure, for backward wave regime is proposed.The remarkable agreement of the analytical model with 3D electromagnetic simulations makes the proposed expression of practical usefulness for backward wave oscillator design up to THz frequencies. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:837–839, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26721
Small‐size WWAN monopole slot antenna with dual‐band band‐stop matching circuit for tablet computer application
Authors: Wong Kin‐Lu , Ma Pei‐Ji
Published: February 2012

A monopole slot antenna printed on a small‐size FR4 substrate of 40 × 10 mm2 to provide two wide operating bands of 824–960 and 1710–2170 MHz for the wireless wide area network operation in the tablet computer is presented. The monopole slot is folded to achieve a compact configuration and is fed by a microstrip feedline loaded with a dual‐band band‐stop matching circuit on the same FR4 substrate. The band‐stop matching circuit can generate two separate parallel resonances at about 1050 and 2250 MHz, which respectively leads to additional resonance occurred nearby the resonant frequencies of the quarter‐wavelength slot mode at about 850 MHz and higher‐order slot mode at about 1900 MHz, thereby resulting in dual‐resonance excitation of the two excited slot modes to respectively cover the GSM850/900 and GSM1800/1900/UMTS operation. The bandwidth‐enhancement technique of using a dual‐band band‐stop matching circuit is reported for the first time in published articles, and its detailed operating principle is described in this study. Performances of the proposed antenna are also discussed. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:875–879, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26723
Microstrip patch array antenna with high isolation characteristic
Authors: Jang Hyeong‐Seok , Lim Won‐Gyu , Son Wang‐Ik , Cha Sung‐Yong , Yu Jong‐Won
Published: February 2012

The design of an integrated rectangular microstrip patch array antenna with enhanced isolation characteristic between transmitter and receiver is presented to produce a full‐duplex transceiver with transmit and receive operation at the same frequency and with the same polarization. This integrated circulator‐like antenna has potential uses in both short‐range communication systems and radar systems. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:973–976, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26727
Transient absorption spectroscopy of a single lateral InGaAs quantum dot molecule
Authors: Wolpert Christian , Wang Lijuan , Rastelli Armando , Schmidt Oliver G. , Giessen Harald , Lippitz Markus
Published: February 2012

Lateral quantum dot molecules promise a scalable approach to quantum registers. The individual neutral exciton states can be controlled by a lateral bias voltage. In this way radiative emission of localized excitons can be switched between the two quantum dots in the molecule. Here, we report on coherent absorption spectroscopy of a single quantum dot molecule. By transient reflection spectroscopy we demonstrate that not only the emission but also the absorption switches from one dot to the other when varying the applied electric field. This result is consistent with Rabi flopping showing a radically suppressed dipole moment for the non‐emitting exciton transition
Affordance‐based indirect task communication for astronaut‐robot cooperation
Authors: Heikkilä Seppo S. , Halme Aarne , Schiele André
Published: February 2012

The problem with human–robot task communication is that robots cannot understand complex human speech, whereas humans cannot efficiently use the fixed task request utterances required by robots. However, future planetary exploration missions will require astronauts on extravehicular activities to communicate task requests to robot assistants by using speech‐ and gesture‐type user interfaces that can be easily embedded in their space suits. The solution proposed in this paper is indirect task communication based on the humanlike ability to utilize object–action relationships in task communication. A conventional task communication method, in which the astronaut needs to communicate all the task parameters explicitly, is compared with communication methods where affordances, i.e., action possibilities, are used to complete the task communication. This comparison is done with three user experiments: one performed with a fully autonomous centauroid robot in a geological exploration work context and two with a simulated robot in a lander assembly work context. The experiments indicate that affordance‐based indirect task communication methods can be used to decrease both the human workload and the task communication times in a planetary exploration type of work context, and that combined direct and indirect task communication methods seem to be preferable from a human point of view. © 2012 Wiley Periodicals, Inc.
Surface modification of austenitic steels by low‐temperature carburization
Authors: Ciancaglioni I. , Donnini R. , Kaciulis S. , Mezzi A. , Montanari R. , Ucciardello N. , Verona‐Rinati G.
Published: February 2012

Austenitic stainless steels are characterized by good corrosion resistance in different environments, but their use is limited because of low hardness and poor wear resistance. Conventional thermochemical surface treatments for improving the mechanical strength of steels induce Cr carbide precipitation and thus are detrimental to corrosion resistance. A low‐temperature (<470 °C) plasma treatment has been developed to overcome this problem and to reduce simultaneously the costs and the time of process. This paper reports the results of a microstructural characterization performed on a series of AISI 316L steel samples treated by plasma‐assisted low‐temperature carburization in different conditions. Microhardness tests and X‐ray diffraction indicated that the best results are achieved by employing a gas mixture with 2% of CH4 in H2. XPS and AES were used to examine the chemical composition of the 20‐µm‐thick hardened layer. The results revealed that this layer is not homogeneous because a 2‐µm‐thick overlayer of graphitic nature forms on the surface. Furthermore, only the plasma treatment with 2% of CH4 guarantees that the whole carbon remains in solid solution, whereas for higher CH4 amounts in the gas mixture, carbide precipitation takes place. Copyright © 2012 John Wiley & Sons, Ltd.
On the use of mutations and testing for debugging
Authors: Nica Mihai , Nica Simona , Wotawa Franz
Published: February 2012

Tools for automated fault localization usually generate too many bug candidates depending on the underlying technique. Hence, more information is required in order to further restrict the number of bug candidates. Approaches that rely on specific knowledge of the program to be debugged, such as variable values at specific positions in the source code, are not easily accessible for users especially in the case of software maintenance. In order to avoid this problem, we suggest integrating testing to restrict the number of bug candidates. In particular, we propose computing possible corrections of the program and from this distinguishing test cases. A distinguishing test case is a test that reveals different output values for two program variants given the same input values. Besides the formal definitions and algorithms, we extend the first empirical results of our approach in this paper. The obtained empirical results show that the use of mutations and distinguishing test cases reduces the number of bug candidates by more than 90% on average. Copyright © 2012 John Wiley & Sons, Ltd.
D-meson decay constants and a check of factorization in non-leptonic B-decays
Authors: Bečirević Damir , Lubicz Vittorio , Sanfilippo Francesco , Simula Silvano , Tarantino Cecilia
Published: February 2012

Abstract

We compute the vector meson decay constants
$ {f_{{D_{{(s)}}^{ * }}}} $
from the simulation of twisted mass QCD on the lattice with N
f = 2 dynamical quarks. When combining these values with the pseudoscalar D
(s)-meson decay constants, we were able (i) to show that the heavy quark spin symmetry breaking effects with the charm quark are large,
$ {f_{{D_s^{ * }}}}/{f_{{{D_s}}}} = 1.26(3) $
, and (ii) to check the factorization approximation in a few specific B-meson non-leptonic decay modes. Besides our main results,
$ {f_{{{D^{ * }}}}} = 278\pm 13\pm 10\,{\text{MeV}} $
, and
$ {f_{{D_s^{ * }}}} = 311\pm 9\,{\text{MeV}} $
, other phenomenologically interesting results of this paper are:
$ {f_{{D_s^{ * }}}}/{f_{{{D^{ * }}}}} = 1.16\pm 0.02\pm 0.06 $
,
$ {f_{{D_s^{ * }}}}/{f_{{{D^{ * }}}}} = 1.46\pm 0.05\pm 0.06 $
, and
$ {f_{{{D_s}}}}/{f_{{{D^{ * }}}}} = 0.89\pm 0.02\pm 0.03 $
. Finally, we correct the value for B(B
0 → D
+
π
−) quoted by PDG, and find B(B
0 → D
+
π
−) = (7.8 ± 1.4) × 10−7. Alternatively, by using the ratios discussed in this paper, we obtain B(B
0 → D
+
π
−) = (8.3 ± 1.0 ± 0.8) × 10−7.
Genome shuffling of Bacillus amyloliquefaciens for improving antimicrobial lipopeptide production and an analysis of relative gene expression using FQ RT-PCR
Authors: Zhao Junfeng , Li Yuanhong , Zhang Chong , Yao Zhengying , Zhang Li , Bie Xiaomei , Lu Fengxia , Lu Zhaoxin
Published: February 2012

Genome shuffling is an efficient approach for the rapid improvement of the yield of secondary metabolites. This study was undertaken to enhance the yield of surfactin produced by Bacillus amyloliquefaciens ES-2-4 using genome shuffling and to examine changes in SrfA expression of the improved phenotype at the transcriptional level. Six strains with subtle improvements in lipopeptide yield were obtained from populations generated by ultraviolet irradiation, nitrosoguanidine, and ion beam mutagenesis. These strains were then subjected to recursive protoplast fusion. A strain library that was likely to yield positive colonies was created by fusing the lethal protoplasts obtained from both ultraviolet irradiation and heat treatments. After two rounds of genome shuffling, a high-yield recombinant F2-38 strain that exhibited 3.5- and 10.3-fold increases in surfactin production in shake flask and fermenter respectively, was obtained. Comparative analysis of synthetase gene expression was conducted between the initial and shuffled strains using FQ (fluorescent quantitation) RT-PCR. Delta CT (threshold cycle) relative quantitation analysis revealed that surfactin synthetase gene (srfA) expression at the transcriptional level in the F2-38 strain was 15.7-fold greater than in the ES-2-4 wild-type. The shuffled strain has a potential application in food and pharmaceutical industries. At the same time, the analysis of improved phenotypes will provide more valuable data for inverse metabolic engineering.
Stability of reactive interfaces in saturated porous media under gravity in the presence of transverse flows
Authors: Hejazi S. H. , Azaiez J.
Published: February 2012

The stability of a horizontal interface between a solution of reactant $A$ on top of another solution of reactant $B$ is analysed. A chemical product $C$ is generated at the interface as a result of a bimolecular chemical reaction $A+ B\ensuremath{\rightarrow} C$. In general, all chemical components are assumed to have different densities and viscosities, and a transverse velocity is introduced parallel to the interface between the reactants. Although the transverse flow is known for its stabilizing effect in viscously unstable non-reactive systems in the presence of an injection velocity, it is shown here that it can actually destabilize an initially stable reactive front. An expression for the critical transverse velocity beyond which an initially stable interface is destabilized is derived in the case of an initial sharp interface for reactants of the same viscosity. The analysis is extended to a diffused profile, and purely buoyancy-driven flows are analysed first in the absence of viscosity contrast and then in the presence of transverse flows and viscosity contrast. Various possible density fingering scenarios are determined based on the relative contribution of each chemical component to the density profile. It is found that the chemical reaction can destabilize a buoyancy-stable initial interface by generating a non-monotonic density profile. Unlike the viscous fingering of a reactive interface, a symmetry in the stability characteristics with respect to density increase or decrease by chemical reaction product is observed in the case of chemically buoyancy-driven flows for identical reactants.
IMPULSIVE PERIODIC SOLUTIONS FOR SINGULAR PROBLEMS VIA VARIATIONAL METHODS
Authors: SUN JUNTAO , O’REGAN DONAL
Published: February 2012

In this paper we study impulsive periodic solutions for second-order nonautonomous singular differential equations. Our proof is based on the mountain pass theorem. Some recent results in the literature are extended.
ON ODD PERFECT NUMBERS
Authors: CHEN FENG-JUAN , CHEN YONG-GAO
Published: February 2012

Let q be an odd prime. In this paper, we prove that if N is an odd perfect number with qα∥N then σ(N/qα)/qα≠p,p2,p3,p4,p1p2,p21p2, where p,p1, p2 are primes and p1≠p2. This improves a result of Dris and Luca [‘A note on odd perfect numbers’, arXiv:1103.1437v3 [math.NT]]: σ(N/qα)/qα≠1,2,3,4,5. Furthermore, we prove that for K≥1 , if N is an odd perfect number with qα ∥N and σ(N/qα)/qα ≤K, then N≤4K8.
AFRICAN COUNTRIES IN THE WORLD TRADING SYSTEM: INTERNATIONAL TRADE, DOMESTIC INSTITUTIONS AND THE ROLE OF INTERNATIONAL LAW
Authors: Desta Melaku Geboye , Hirsch Moshe
Published: February 2012

This article addresses an important and complex subject relating to the link between international law and economic development. There is broad agreement that trade liberalization and participation in foreign markets play an important role in economic development. Countries in Sub-Saharan Africa (SSA) have generally pursued a liberalization route over the past two decades, but their economic performance has been deeply disappointing. In this article, we look at seven countries in the Horn of Africa and examine, from legal and institutional perspectives, the central question of why these countries have failed to translate their comparative advantage, particularly in the livestock sector, into meaningful trade-led economic growth. In order to answer this question, we have reviewed the relevant legal and policy instruments and the literature, visited five of the seven countries, and interviewed different players in the livestock value chain. Analysis of the evidence reveals that the main impediments to trade relate to rising sanitary import requirements in foreign markets and weak institutional capacity within the Horn. The limited technical and financial resources available to these countries also reduce their capacity to meet these standards. Meaningful institutional change requires substantial involvement of local actors and it takes place incrementally and over the long term. International law can play a role in this process by promoting the rule of law and tackling corruption, facilitating capacity-building, and encouraging regional integration.
EU COMPETITION LAW ENFORCEMENT: IS BRUSSELS I SUITED TO DEALING WITH ALL THE CHALLENGES?
Authors: Danov Mihail
Published: February 2012

There are arguments indicating that Brussels I could be applicable to cross-border competition law proceedings before a National Competition Authority located in one Member State and private EU competition law proceedings before another Member State court. However, an analysis of the current private international law framework appears to indicate that Brussels I is not well suited to deal with the difficulties that could arise in this context. Given the fact that, in the new proposal for a regulation on jurisdiction and the recognition and enforcement of judgments there is no indication that special jurisdictional bases for competition law actions in the successor to Brussels I are on anyone's agenda, an option for a reform may be setting up a new and special regulation to be applicable with regard to EU competition law claims only.
Choosing to Collaborate: Yi Kwang-su and the Moral Subject in Colonial Korea
Authors: Treat John Whittier
Published: February 2012

Today historians hesitate to judge collaborators with the Axis powers in World War II, citing the impossibility of putting oneself in the often untenable position collaborators found themselves. Nonetheless, contemporary moral philosophy continues to ponder the ethical choice of complicity versus resistance. Yi Kwang-su (1892–1950?), Korea's most distinguished modern novelist as well as one of its more notorious pro-Japanese partisans during the colonial period, offers a compelling test case for how we might attempt to not only understand, but also morally adjudicate, his support of Japan's occupation of his country. With the ongoing debate over collaboration with the German Reich in mind, I contend that the case of colonial Korea presents us with important first-order ethical issues to resolve.
A comparison ofToxocara canisembryonation under controlled conditions in soil and hair
Authors: Keegan J. Devoy , Holland C.V.
Published: February 2012

Toxocaraspp. eggs require a period of time under appropriate environmental conditions to become infective to definitive and paratenic hosts. Temperature and humidity are important factors known to affect the levels of development in soil. We aimed to investigate whether the eggs ofT. caniscould embryonate in dog hair under controlled conditions of temperature and humidity and, if so, to what degree. No previous work had been carried out on embryonation in hair under controlled conditions. Soil samples exposed to the same conditions as the hair samples were considered a suitable comparison in order to investigate differing levels of development. Development at two temperatures (10°C and 20°C) and the addition of water to samples was investigated over a period of 8 weeks. Importantly, we demonstrated that unembryonatedT. caniseggs are capable of development in hair under controlled conditions. The rate of development is lower than that observed in soil, but remains biologically significant in terms of the overall numbers of potentially infective embryonated eggs present. Temperature is responsible for the rate of embryonation while moisture is essential for encouraging development and maintaining egg viability in general. In light of these findings the transmission ofToxocaraspp. as a result of direct contact with well-cared-for owned dogs seems unlikely, but should not be ignored.
New advances in thein-vitroculture ofDientamoeba fragilis
Authors: MUNASINGHE VARUNI S. , STARK D. , ELLIS J. T.
Published: February 2012

Dientamoeba fragilisis an intestinal protozoan in humans that is commonly associated with diarrhoea and other gastrointestinal complaints. Studies conducted to investigate the biology of this parasite are limited by methods forin vitrocultivation. The objective of this study was to improve a biphasic culture medium, based on the Loeffler's slope, by further supplementation in order to increase the yield of trophozoites in culture. The currentin vitroculture ofD. fragilisis a xenic culture with a mix of bacteria. Three different liquid overlays were evaluated including Earle's balanced salt solution (EBSS), PBS and Dulbecco's modified PBS (DPBS), for their ability to support thein vitrogrowth ofD. fragilistrophozoites. Out of these 3 overlays EBSS gave the highest increase in the trophozoite numbers. The effect of supplementation was analysed by supplementing EBSS with ascorbic acid, ferric ammonium citrate, L-cysteine, cholesterol and alpha-lipoic acid and quantification ofin vitrogrowth by cell counts. A new liquid overlay is here described based upon EBSS supplemented with cholesterol and ferric ammonium citrate that, in conjunction with the Loeffler's slope, supports the growth ofD. fragilistrophozoitesin vitro. This modified overlay supported a 2-fold increase in the numbers of trophozoite in culture from all 4D. fragilisisolates tested, when compared to a PBS overlay. These advances enable the harvest of a larger number of trophozoites needed for further studies on this parasite.
Pangloss revisited: a critique of the dilution effect and the biodiversity-buffers-disease paradigm
Authors: RANDOLPH S. E. , DOBSON A. D. M.
Published: February 2012

The twin concepts of zooprophylaxis and the dilution effect originated with vector-borne diseases (malaria), were driven forward by studies on Lyme borreliosis and have now developed into the mantra “biodiversity protects against disease”. The basic idea is that by diluting the assemblage of transmission-competent hosts with non-competent hosts, the probability of vectors feeding on transmission-competent hosts is reduced and so the abundance of infected vectors is lowered. The same principle has recently been applied to other infectious disease systems – tick-borne, insect-borne, indirectly transmitted via intermediate hosts, directly transmitted. It is claimed that the presence of extra species of various sorts, acting through a variety of distinct mechanisms, causes the prevalence of infectious agents to decrease. Examination of the theoretical and empirical evidence for this hypothesis reveals that it applies only in certain circumstances even amongst tick-borne diseases, and even less often if considering the correct metric – abundance rather than prevalence of infected vectors. Whether dilution or amplification occurs depends more on specific community composition than on biodiversityper se. We warn against raising a straw man, an untenable argument easily dismantled and dismissed. The intrinsic value of protecting biodiversity and ecosystem function outweighs this questionable utilitarian justification.
Interleukin-6, C-reactive protein and interleukin-10 after antidepressant treatment in people with depression: a meta-analysis
Authors: Hiles S. A. , Baker A. L. , de Malmanche T. , Attia J.
Published: February 2012

Background

Cross-sectional studies support an association between depression and inflammatory markers. However, little is known of their relationship in the context of antidepressant treatment. Our aim was to explore via meta-analysis whether antidepressant treatment is associated with a reduction in three inflammatory markers associated with depression.

Method

A computerized search of EMBASE, Medline, PsycINFO and Cochrane Library databases was completed using subject headings for depression and either interleukin-6, C-reactive protein or interleukin-10, selecting studies which reported circulating levels of inflammatory markers before and after antidepressant treatment for people with depression. Outcome and moderator variables were coded for analysis, including inflammatory marker change, depression severity change, age, gender ratio, assay brand, treatment response and weight change.

Results

Pooled effect sizes showed a significant decrease in interleukin-6 (n=14, d=−0.42, p=0.02), marginally significant decrease in C-reactive protein (n=8, d=−0.57, p=0.05) and a non-significant decrease in interleukin-10 (n=3, d=−0.45, p=0.14) after treatment. High levels of heterogeneity were observed, which may be associated with clinical variations between the studies such as weight gain, anxiety, incomplete remission and other individual differences and co-morbidities.

Conclusions

The findings of this meta-analysis indicate that there may be a normalization of overactive inflammatory processes following antidepressant treatment.
A note on Borel–Cantelli lemmas for non-uniformly hyperbolic dynamical systems
Authors: HAYDN NICOLAI , NICOL MATTHEW , PERSSON TOMAS , VAIENTI SANDRO
Published: February 2012

Let (Bi) be a sequence of measurable sets in a probability space (X,ℬ,μ) such that ∑ ∞n=1μ(Bi)=∞. The classical Borel–Cantelli lemma states that if the sets Bi are independent, then μ({x∈X:x∈Bi infinitely often})=1. Suppose (T,X,μ) is a dynamical system and (Bi) is a sequence of sets in X. We consider whether Tix∈Bi infinitely often for μ almost every x∈X and, if so, is there an asymptotic estimate on the rate of entry? If Tix∈Bi infinitely often for μ almost every x, we call the sequence (Bi) a Borel–Cantelli sequence. If the sets Bi :=B(p,ri) are nested balls of radius ri about a point p, then the question of whether Tix∈Bi infinitely often for μ almost every x is often called the shrinking target problem. We show, under certain assumptions on the measure μ, that for balls Bi if μ(Bi)≥i−γ, 0<γ<1, then a sufficiently high polynomial rate of decay of correlations for Lipschitz observables implies that the sequence is Borel–Cantelli. If μ(Bi)≥C1 /i, then exponential decay of correlations implies that the sequence is Borel–Cantelli. We give conditions in terms of return time statistics which quantify Borel–Cantelli results for sequences of balls such that μ(Bi)≥C/i. Corollaries of our results are that for planar dispersing billiards and Lozi maps, sequences of nested balls B(p,1/i) are Borel–Cantelli. We also give applications of these results to a variety of non-uniformly hyperbolic dynamical systems.
THE INFLUENCE OF SOILS ON THE FLORISTIC COMPOSITION AND COMMUNITY STRUCTURE OF AN AREA OF BRAZILIAN CERRADO VEGETATION
Authors: Neri A. V. , Schaefer C. E. G. R. , Silva A. F. , Souza A. L. , Ferreira-Junior W. G. , Meira-Neto J. A. A.
Published: February 2012

This study investigated the influence of soil factors on the structure, richness and distribution of woody Cerrado species within the National Forest of Paraopeba, Minas Gerais State, Brazil. Individuals with basal stem circumference ≥ 10 cm were sampled in five plots of 20 × 100 m. The study was conducted in five environments with different physiognomies and types of soils. A total of 132 species were recorded. The species with the greatest importance values varied between different areas, as did structure. Canonical correspondence analysis ordination showed three different groups closely related to soil fertility and Al levels. These relations were also confirmed by Pearson’s correlation where richness was positively related to pH, K, Ca, Mg and P and negatively to Al. The basal area was positively correlated with levels of P, Mg, Ca and T (base saturation) and negatively with Al, also using Pearson’s correlation. Likewise, density was positively correlated with Mg and negatively with Al. The analysis shows that soil fertility and the concentration of Al are two of the most important factors responsible for structural and floristic variation and for differentiating dystrophic and mesotrophic Cerradão.
A REVISION OF AMOMUM (ZINGIBERACEAE) IN CAMBODIA, LAOS AND VIETNAM
Authors: Lamxay V. , Newman M. F.
Published: February 2012

The species of Amomum Roxb. (Zingiberaceae) in Cambodia, Laos and Vietnam are revised. Thirty-five species and two varieties are recognised, most names are typified, and detailed descriptions and a key are provided. Conservation assessments of all species are given. Eleven new species are described: Amomum calcaratum Lamxay & M.F.Newman, Amomum calcicolum Lamxay & M.F.Newman, Amomum celsum Lamxay & M.F.Newman, Amomum chevalieri Gagnep. ex Lamxay, Amomum chryseum Lamxay & M.F.Newman, Amomum glabrifolium Lamxay & M.F.Newman, Amomum plicatum Lamxay & M.F.Newman, Amomum prionocarpum Lamxay & M.F.Newman, Amomum rubidum Lamxay & N.S.Lý, Amomum stephanocoleum Lamxay & M.F.Newman and Amomum tenellum Lamxay & M.F.Newman.
A molecular method to assess bioburden embedded within silicon-based resins used on modern spacecraft materials
Authors: Stam Christina N. , Bruckner James , Spry J. Andy , Venkateswaran Kasthuri , La Duc Myron T.
Published: February 2012

Current assessments of bioburden embedded in spacecraft materials are based on work performed in the Viking era (1970s), and the ability to culture organisms extracted from such materials. To circumvent the limitations of such approaches, DNA-based techniques were evaluated alongside established culturing techniques to determine the recovery and survival of bacterial spores encapsulated in spacecraft-qualified polymer materials. Varying concentrations ofBacillus pumilusSAFR-032 spores were completely embedded in silicone epoxy. An organic dimethylacetamide-based solvent was used to digest the epoxy and spore recovery was evaluated viagyrB-targeted qPCR, direct agar plating, most probably number analysis, and microscopy. Although full-strength solvent was shown to inhibit the germination and/or outgrowth of spores, dilution in excess of 100-fold allowed recovery with no significant decrease in cultivability. Similarly, qPCR (quantitative PCR) detection sensitivities as low as ∼103CFU ml−1were achieved upon removal of inhibitory substances associated with the epoxy and/or solvent. These detection and enumeration methods show promise for use in assessing the embedded bioburden of spacecraft hardware.
The galactic habitable zone in elliptical galaxies
Authors: Suthar Falguni , McKay Christopher P.
Published: February 2012

The concept of a Galactic Habitable Zone (GHZ) was introduced for the Milky Way galaxy a decade ago as an extension of the earlier concept of the Circumstellar Habitable Zone. In this work, we consider the extension of the concept of a GHZ to other types of galaxies by considering two elliptical galaxies as examples, M87 and M32. We argue that the defining feature of the GHZ is the probability of planet formation which has been assumed to depend on the metallicity. We have compared the metallicity distribution of nearby stars with the metallicity of stars with planets to document the correlation between metallicity and planet formation and to provide a comparison to other galaxies. Metallicity distribution, based on the [Fe/H] ratio to solar, of nearby stars peaks at [Fe/H]≈−0.2 dex, whereas the metallicity distribution of extrasolar planet host stars peaks at [Fe/H]≈+0.4 dex. We compare the metallicity distribution of extrasolar planet host stars with the metallicity distribution of the outer star clusters of M87 and M32. The metallicity distribution of stars in the outer regions of M87 peaks at [Fe/H]≈−0.2 dex and extends to [Fe/H]≈+0.4 dex, which seems favourable for planet formation. The metallicity distribution of stars in the outer regions of M32 peaks at [Fe/H]≈−0.2 dex and extends to a much lower [Fe/H]. Both elliptical galaxies met the criteria of a GHZ. In general, many galaxies should support habitable zones.
Sampling methane in hydrothermal minerals on Earth and Mars
Authors: McMahon Sean , Parnell John , Blamey Nigel J. F.
Published: February 2012

The source of Martian atmospheric methane is unknown. On Earth, hydrothermal mineral deposits contain ancient methane together with a host of chemical and geological lines of evidence for the mechanism of gas production. Such deposits are therefore potentially attractive sampling sites on Mars. In order to evaluate this potential, hydrothermal calcite veins were sampled across the Caithness region of Scotland and analysed for methane by an incremental-crushing mass spectrometry technique that may be adaptable to Mars rovers. Methane was detected in all samples. Variations in the quantity of methane released were found to relate directly to the geological history of the localities. Calcite particle size was found to affect measurements in a systematic and informative way. Oxidative weathering had no discernable effect on methane recoverability. These results suggest that the technique is sensitive and informative enough to deserve consideration for missions to Mars.
Interannual variability of chlorophyll and the influence of low‐frequency climate modes in the North Atlantic subtropical gyre
Authors: Cianca A. , Godoy J. M. , Martin J. M. , Perez‐Marrero J. , Rueda M. J. , Llinás O. , Neuer S.
Published: February 2012

The impact of low‐frequency climate modes on the large‐scale variability of chlorophyll‐a (a proxy for phytoplankton biomass) concentration in the subtropics is little known. Here we examined the concurrent monthly chlorophyll‐a and hydrographical records obtained at two subtropical time series stations (Bermuda Atlantic Time series Study, BATS and European Station for Time series in the Ocean Canary Islands, ESTOC) from the beginning of the time series (1989 at BATS and 1994 at ESTOC) to 2003, in order to analyze its seasonal and interannual variability and investigate the potential correlation with large‐scale atmospheric oscillations. At BATS, Chl‐a variations are mainly caused by differences in the convective mixing and mesoscale phenomena. Variability in winter mixing is a significant factor at ESTOC as exemplified by years with anomalously deep mixed layer depths. An additional nutrient source causing Chl‐a variability at this station likely occurs due to nutrient advection driven by the baroclinic flow caused by the Trade Winds during summertime. We found that interannual variability in mean integrated total Chl‐a (TChl‐a) is significantly correlated with temperature and salinity anomalies at BATS. Chl‐a also covaried with changes in temperature although the correlation was not significant at ESTOC. We could not find any direct correlation between TChl‐a and NAO at BATS; the correlation improved between TChl‐a and NAO +1 year but was still insignificant. However, significant correlations were found for ESTOC between TChl‐a anomalies and ENSO (El Niño Southern Oscillation) +3 years and NAO +1 year time lag.
Simulation of urban and regional air pollution in Bangladesh
Authors: Muntaseer Billah Ibn Azkar M. A. , Chatani Satoru , Sudo Kengo
Published: February 2012

We have developed a regional scale air quality simulation using the Weather Research and Forecasting (WRF) – Community Multiscale Air Quality Model (CMAQ) to assess the suitability of such an advanced modeling system for predicting the air quality of Bangladesh and its surrounding region. The Regional Emission Inventory in Asia (REAS) was used as the emission input in this modeling approach. Both meteorological and chemical model performance were evaluated with observations including satellite data. Comparison between simulated and observed meteorological parameters revealed that the WRF can generate the necessary meteorological inputs for CMAQ. Comparison of observed and simulated concentrations of different air pollutants revealed that CMAQ greatly underestimates the concentrations of key pollutants. Comparison with satellite observations revealed that CMAQ reproduces the spatial distribution of NO2with some underestimation in Bangladesh and India. The simulated AOD and satellite‐retrieved AOD showed good temporal and spatial agreement mutually, with a correlation coefficient of 0.58. Sensitivity simulation using higher horizontal resolution emission data made by re‐gridding the REAS inventory with the population distribution improved the CMAQ performance. Nevertheless, CMAQ underestimated the pollutant concentrations in Dhaka. Uncertainties in the emission inventory and in the lack of time variation in emissions input mainly contributed to the model underestimation. Model predictions show that 36–72% PM10 and 15–60% PM2.5 in Dhaka might be contributed from brick kiln emissions in monthly average of January 2004. The chemical composition of PM2.5showed that the considerable amounts of secondary aerosols in Dhaka and carbonaceous components (particularly organic carbon) are most responsible for the model underestimation. Results suggest that improvements of emission inputs and more detailed sensitivity analysis of CMAQ model are important to assess the reliability and applicability of WRF‐CMAQ modeling system in this region.
Soil water content variability at the hillslope scale: Impact of surface sealing
Authors: Sela Shai , Svoray Tal , Assouline Shmuel
Published: February 2012

Spatial and temporal variability of water content in the upper soil layer, close to the surface, affects the intensity of hydrological processes. The impact of accounting for soil surface sealing on the spatial and temporal variability of the water content at the hillslope scale was studied in a semiarid environment. Relevant physical properties of the experimental site were derived by means of extensive field surveys, resulting in a detailed database used to characterize the 8240 cells used to represent the hillslope domain. The simulated spatial and temporal water content variability was achieved by aggregating a numerical 1‐D simulation at each of these cells. Accounting for surface sealing improved water content predictions, more efficiently during the drying regime. Furthermore, extensive synthetic simulations show the sealed layer to be a highly efficient mechanism reducing temporal water content variability, compared to an unsealed system. It was also found that reduced evaporation in the sealed domain compensates for the loss in infiltrated water due to runoff enhancement. Depending on rainfall intensity and soil depth, a transition could occur from a positive feedback mechanism where the seal layer suppresses evaporation and conserves water stored in the profile to a negative one where the seal layer mainly reduces infiltration and increases water losses through runoff. Thus, the sealing process was found to substantially affect water budgets at all observed scales in the experimental site.
Predicting Spanish–English Bilingual Children’s Language Abilities
Authors: Hammer Carol Scheffner , Komaroff Eugene , Rodriguez Barbara L. , Lopez Lisa M. , Scarpino Shelley E. , Goldstein Brian
Published: February 2012

Purpose

In this study, the authors investigated factors that affect bilingual children’s vocabulary and story recall abilities in their 2 languages.

Method

Participants included 191 Latino families and their children, who averaged 59 months of age. Data on parental characteristics and children’s exposure to and usage of Spanish and English were collected. The authors assessed children’s Spanish and English vocabulary and story recall abilities using subtests of the Woodcock–Muñoz Language Survey—Revised (Woodcock, Muñoz-Sandoval, Ruef, & Alvarado, 2005).

Results

Sizeable percentages of variation in children’s English (
R
2
= .61) and Spanish (
R
2
= .55) vocabulary scores were explained by children’s exposure to, and usage of, each language and maternal characteristics. Similarly, variations in children’s story recall scores in English (
R
2
= .38) and Spanish (
R
2
= .19) were also explained by the factors considered in this investigation. However, the authors found that different sets of factors in each category affected children’s vocabulary and story recall abilities in each language.

Conclusions

Children’s exposure to and usage of their two languages as well as maternal characteristics play significant roles in bilingual individuals' language development. The results highlight the importance of gathering detailed sociolinguistic information about bilingual children when these children are involved in research and when they enter the educational system.
Effect of a lateral electric field on an off-center single dopant confined in a thin quantum disk
Authors: Dujardin F. , Oukerroum A. , Feddi E. , Bosch Bailach J. , Martínez-Pastor J. , Zazi M.
Published: February 2012

The effect of a lateral electric field on a donor impurity confined in a thin quantum disk is studied theoretically in the framework of mass approximation and using the Ritz variational approach. We show that the binding energy depends on several parameters: the dot size, the position of the donor impurity, the lateral field strength, and its orientation relative to the axis containing the impurity. When the impurity is located at one edge and the electric field is oriented in the opposite direction, the binding energy is considerably reinforced due to the simultaneous additive effects of coulombic potential and electrostatic force. The competition between these effects modifies considerably the probability densities and allows a better comprehension of the binding energy variations. This interesting behavior can contribute to an better understanding of the experimental optical response.