bluuebunny/crossref_metadata_2025 huggingface dataset:
Biological pathways as communicating computer systems
Authors: Kwiatkowska Marta Z. , Heath John K.
Published: August 2009

Time and cost are the enemies of cell biology. The number of experiments required to rigorously dissect and comprehend a pathway of even modest complexity is daunting. Methods are needed to formulate biological pathways in a machine-analysable fashion, which would automate the process of considering all possible experiments in a complex pathway and identify those that command attention. In this Essay, we describe a method that is based on the exploitation of computational tools that were originally developed to analyse reactive communicating computer systems such as mobile phones and web browsers. In this approach, the biological process is articulated as an executable computer program that can be interrogated using methods that were developed to analyse complex software systems. Using case studies of the FGF, MAPK and Delta/Notch pathways, we show that the application of this technology can yield interesting insights into the behaviour of signalling pathways, which have subsequently been corroborated by experimental data.
Identification of a novel mouse P4-ATPase family member highly expressed during spermatogenesis
Authors: Xu Peng , Okkeri Juha , Hanisch Susanne , Hu Rui-Ying , Xu Qin , Pomorski Thomas Günther , Ding Xiao-Yan
Published: August 2009

P4-ATPases are transmembrane proteins unique to eukaryotes that play a fundamental role in vesicular transport. They have been proposed to act as phospholipid flippases thereby regulating lipid topology in cellular membranes. We cloned and characterized a novel murine P4-ATPase that is specifically expressed in testis, and named it FetA (flippase expressed in testis splicing form A). When expressed in Saccharomyces cerevisiae, FetA localizes partially to the plasma membrane resulting in increased internalization of NBD-labeled phosphatidylethanolamine and phosphatidylcholine, supporting a role for FetA in the inward lipid translocation across cellular membranes. In mouse testis, FetA protein is detected in gamete cells, from pachytene spermatocytes to mature sperms, and its intracellular localization is tightly related with acrosome formation, a process that involves intensive intracellular vesicle formation and fusion. Furthermore, loss-of-function of FetA by RNA interference in mastocytoma P815 cells profoundly perturbs the structural organization of the Golgi complex and causes loss of constitutive secretion at lower temperature. Our findings point to an essential role of FetA in Golgi morphology and secretory function, suggesting a crucial role for this novel murine P4-ATPase in spermatogenesis.
GAK, a regulator of clathrin-mediated membrane traffic, also controls centrosome integrity and chromosome congression
Authors: Shimizu Hiroyuki , Nagamori Ippei , Yabuta Norikazu , Nojima Hiroshi
Published: August 2009

Cyclin G-associated kinase (GAK) is an association partner of clathrin heavy chain (CHC) and is essential for clathrin-mediated membrane trafficking. Here, we report two novel functions of GAK: maintenance of proper centrosome maturation and of mitotic chromosome congression. Indeed, GAK knockdown by siRNA caused cell-cycle arrest at metaphase, which indicates that GAK is required for proper mitotic progression. We found that this impaired mitotic progression was due to activation of the spindle-assembly checkpoint, which senses protruded, misaligned or abnormally condensed chromosomes in GAK-siRNA-treated cells. GAK knockdown also caused multi-aster formation, which was due to abnormal fragmentation of pericentriolar material, but not of the centrioles. Moreover, GAK and CHC cooperated in the same pathway and interacted in mitosis to regulate the formation of a functional spindle. Taken together, we conclude that GAK and clathrin function cooperatively not only in endocytosis, but also in mitotic progression.
The impact properties of a polyamide 6– polytetrafluoroethylene composite
Authors: Li J , Zhang Y F
Published: August 2009

Polyamide 6 (PA6)-filled polytetrafluoroethylene (PTFE) at different compositions has been successfully prepared in a corotating twin screw extruder where PTFE acts as the polymer matrix and PA6 as the dispersed phase. The morphology and impact properties of these blends were investigated using a scanning electron microscope. The presence of PA6 particles dispersed in the PTFE continuous phase exhibited a coarse morphology. Increasing PA6 contents in the blend improved the impact properties at weak deformation. It was found that the interfacial adhesion played an important role in the creation of an interphase that was formed by the interaction between the PTFE and PA6. This induced an improvement in impact properties. In addition, the optimum impact properties were obtained when the content of PA6 is 30 vol%.
Practice Abstracts
Authors: Denton Brian T.
Published: August 2009

The goal of “Practice Abstracts” is to present interesting, topical, and novel applications of operations research methodology to a wide range of industrial applications. “Practice Abstracts” are intended to provide Interfaces readers with short (2–4 page) descriptions of the most relevant aspects of operations research-based projects, in a form that is accessible to academics and practitioners in other organizations. Contributions should be sent for evaluation to the editor of “Practice Abstracts,” Brian T. Denton, Edward P. Fitts Department of Industrial and Systems Engineering, 376 Daniels Hall, North Carolina State University, 111 Lampe Drive, Campus Box 7906, Raleigh, North Carolina 27695, bdenton@ncsu.edu.
Governance of International Business Relationships: A Cross-Cultural Study on Alternative Governance Modes
Authors: Homburg Christian , Cannon Joseph P. , Krohmer Harley , Kiedaisch Ingo
Published: August 2009

The authors examine the effects of both transnationality (cross-border versus domestic exchange) and national culture (U.S. versus German buyers) on the use of three primary modes of governance: (1) the market mechanism, (2) trust, and (3) formal contracts. Drawing on theory, the authors develop a series of hypotheses. Then, they test the model on a sample of more than 500 buyer–supplier relationships. The results show that transnationality and culture both affect the choice of governance modes.
Key Factors for Successful Export Performance for Small Firms
Authors: Brouthers Lance Eliot , Nakos George , Hadjimarcou John , Brouthers Keith D.
Published: August 2009

What key factors result in superior export performance for small firms from small countries? Drawing on the internationalization process model and organizational learning theory, the authors hypothesize and find that (1) emphasizing international sales while (2) restricting exports to a few foreign markets results in superior perceived export performance for the sample of small firms from Greece and several Caribbean countries. Emphasizing international sales while focusing on a few markets enables small firms to develop expertise in those markets, build strong distribution networks, and manage export activities effectively.
Mesograzers in Posidonia oceanica meadows: an update of data on gastropod-epiphyte-seagrass interactions
Authors: Gacia Esperança , Costalago David , Prado Patricia , Piorno Diana , Tomas Fiona
Published: August 2009

Information on dietary habits of mesograzers in Posidonia oceanica seagrass meadows is scarce and restricted to a few species. Here we provide data on the most likely food sources for eight gastropod species inferred from stable isotope data. We observed very similar isotopic signals for all species regardless of trophic guild category, indicating similar consumption behaviour with a main diet contribution from epiphytes. We also review the state of knowledge on gastropod-epiphyte-seagrass interactions, with particular emphasis on the scarcity of studies derived from Mediterranean systems. Laboratory experiments showed that under moderately nutrient-enriched conditions, two species of gastropods (Bittium reticulatum and Jujubinus striatus) were controlling epiphyte biomass at high grazer densities, with no consequences for seagrass performance. Finally, the results of a long-term in situ fertilisation experiment showed that the δ15N signal for seagrass, epiphytes and gastropods reflects experimentally induced eutrophication, thus cascading up nutrient effects throughout the food web.
Sigma Phase in Chromium-Molybdenum Alloys with Iron or Nickel
Authors: Putman John W. , Grant N. J. , Bloom D. S.
Published: August 2009

Because the brittleness of chromium-base alloys for high-temperature duty was believed to be due in part to sigma formation, research was undertaken to study the formation of sigma in simple alloys of chromium, molybdenum, and iron. The extent of the sigma phase in the chromium-molybdenum-iron ternary diagram has been determined, and some of the properties of the sigma occurring in this system have been described. The experiments indicate that molybdenum increases the high-temperature stability of sigma in iron-chromium alloys, and that the sigma phase in the 60Cr-25Mo-15Fe alloy is stable at 1100 C. With regard to this alloy, the temperature effect is such that at lower temperatures the tendency for the formation of sigma is increased provided that sufficient time be allowed for the transformation. The sigma phase has been found to occur in the chromium-molybdenum-nickel ternary alloys, although its occurrence has not been reported in any of the three constituent binaries. X-ray diffraction data on chromium-molybdenum-nickel sigma are included.
A Switch in Retrograde Signaling from Survival to Stress in Rapid-Onset Neurodegeneration
Authors: Perlson Eran , Jeong Goo-Bo , Ross Jenny L. , Dixit Ram , Wallace Karen E. , Kalb Robert G. , Holzbaur Erika L. F.
Published: August 2009

Retrograde axonal transport of cellular signals driven by dynein is vital for neuronal survival. Mouse models with defects in the retrograde transport machinery, including the Loa mouse (point mutation in dynein) and the Tgdynamitinmouse (overexpression of dynamitin), exhibit mild neurodegenerative disease. Transport defects have also been observed in more rapidly progressive neurodegeneration, such as that observed in the SOD1G93Atransgenic mouse model for familial amyotrophic lateral sclerosis (ALS). Here, we test the hypothesis that alterations in retrograde signaling lead to neurodegeneration.In vivo,in vitro, and live-cell imaging motility assays show misregulation of transport and inhibition of retrograde signaling in the SOD1G93Amodel. However, similar inhibition is also seen in the Loa and Tgdynamitinmouse models. Thus, slowing of retrograde signaling leads only to mild degeneration and cannot explain ALS etiology. To further pursue this question, we used a proteomics approach to investigate dynein-associated retrograde signaling. These data indicate a significant decrease in retrograde survival factors, including P-Trk (phospho-Trk) and P-Erk1/2, and an increase in retrograde stress factor signaling, including P-JNK (phosphorylated c-Jun N-terminal kinase), caspase-8, and p75NTRcleavage fragment in the SOD1G93Amodel; similar changes are not seen in the Loa mouse. Cocultures of motor neurons and glia expressing mutant SOD1 (mSOD1) in compartmentalized chambers indicate that inhibition of retrograde stress signaling is sufficient to block activation of cellular stress pathways and to rescue motor neurons from mSOD1-induced toxicity. Hence, a shift from survival-promoting to death-promoting retrograde signaling may be key to the rapid onset of neurodegeneration seen in ALS.
GABAergic Transmission to Gonadotropin-Releasing Hormone (GnRH) Neurons Is Regulated by GnRH in a Concentration-Dependent Manner Engaging Multiple Signaling Pathways
Authors: Chen Peilin , Moenter Suzanne M.
Published: August 2009

Gonadotropin-releasing hormone (GnRH) neurons are the central regulators of fertility. GnRH stimulates or inhibits GnRH neuronal activity depending on dose. The mechanisms for these actions remain unknown. We hypothesized GnRH acts in part by altering fast synaptic transmission to GnRH neurons. GABAergic and glutamatergic postsynaptic currents (PSCs), both of which can excite these neurons, were recorded from GnRH neurons in brain slices from adult intact and orchidectomized (ORX) males. ORX enhanced the frequency of GABA transmission to GnRH neurons, but had no effect on glutamatergic transmission. Effects of ORX on GABAergic transmission were reversed by estradiol replacement, suggesting GABA is a mediator of steroid feedback in males. GABAergic neurons express type-1 GnRH receptor (GnRHR-1). Low GnRH (20 nm) reduced GABAergic PSC frequency in GnRH neurons from both ORX and intact mice. High GnRH (2 μm) had no effect on either GABAergic or glutamatergic transmission to GnRH neurons. To investigate mechanisms mediating low-dose GnRH suppression of GABAergic transmission, GABAergic PSCs were recorded after arresting Gαiactivity with pertussis toxin (PTX). PTX abolished the suppressive effect of low GnRH. Moreover, PTX uncovered a stimulatory effect of high GnRH on GABAergic transmission. These data suggest low-dose GnRH suppresses GnRH firing rate in part by decreasing GABAergic transmission to the GnRH neurons, independent of gonadal hormone milieu. Low-dose GnRH appears to exert the suppressive effect by activating GnRHR-I coupled to Gαi. The concentration-dependent effects of GnRH may be mediated in part by changes in affinity of GnRH to GnRHR-I coupled to different Gαproteins.
Requirement for Protein Synthesis at Developing Synapses
Authors: Sebeo Joseph , Hsiao Kuangfu , Bozdagi Ozlem , Dumitriu Dani , Ge Yongchao , Zhou Qiang , Benson Deanna L.
Published: August 2009

Activity and protein synthesis act cooperatively to generate persistent changes in synaptic responses. This forms the basis for enduring memory in adults. Activity also shapes neural circuits developmentally, but whether protein synthesis plays a congruent function in this process is poorly understood. Here, we show that brief periods of global or local protein synthesis inhibition decrease the synaptic vesicles available for fusion and increase synapse elimination. Ca2+/calmodulin-dependent protein kinase II (CaMKII) is a critical target; its levels are controlled by rapid turnover, and blocking its activity or knocking it down recapitulates the effects of protein synthesis inhibition. Mature presynaptic terminals show decreased sensitivity to protein synthesis inhibition, and resistance coincides with a developmental switch in regulation from CaMKII to PKA (protein kinase A). These findings demonstrate a novel mechanism regulating presynaptic activity and synapse elimination during development, and suggest that protein translation acts coordinately with activity to selectively stabilize appropriate synaptic interactions.
Stability of Electrical Coupling despite Massive Developmental Changes of Intrinsic Neuronal Physiology
Authors: Parker Philip R. L. , Cruikshank Scott J. , Connors Barry W.
Published: August 2009

Gap junctions mediate metabolic and electrical interactions between some cells of the CNS. For many types of neurons, gap junction-mediated electrical coupling is most prevalent during early development, then decreases sharply with maturation. However, neurons in the thalamic reticular nucleus (TRN), which exert powerful inhibitory control over thalamic relay cells, are electrically coupled in relatively mature animals. It is not known whether TRN cells or any neurons that are electrically coupled when mature are also coupled during early development. We used dual whole-cell recordings in mouse brain slices to study the postnatal development of electrical and chemical synapses that interconnect TRN neurons. Inhibitory chemical synapses were seen as early as postnatal day 4 but were infrequent at all ages, whereas TRN cells were extensively connected by electrical synapses from birth onward. Surprisingly, the functional strength of electrical coupling, assayed under steady-state conditions or during spiking, remained relatively constant as the brain matured despite dramatic concurrent changes of intrinsic membrane properties. Most notably, neuronal input resistances declined almost eightfold during the first two postnatal weeks, but there were offsetting increases in gap junctional conductances. This suggests that the size or number of gap junctions increase homeostatically to compensate for leakier nonjunctional membranes. Additionally, we found that the ability of electrical synapses to synchronize high frequency subthreshold signals improved as TRN cells matured. Our results demonstrate that certain central neurons may maintain or even increase their gap junctional communication as they mature.
The crystal structure and refined formula of mountainite, KNa2Ca2[Si8O19(OH)] · 6 H2O
Authors: Zubkova Natalia V. , Pekov Igor V. , Pushcharovsky Dmitry Yu. , Chukanov Nikita V.
Published: August 2009

Mountainite was described as a new mineral in 1957 with formula (Ca,Na2,K2)16Si32O80· 24 H2O; its crystal structure was not solved up to now. We studied the structure of mountainite from the Yubileinaya pegmatite, Lovozero alkaline complex, Kola Peninsula, Russia. Mountainite is monoclinic,P2/c,a= 13.704(2),b= 6.5760(10),c= 13.751(2) Å,β= 105.752(10)°,V= 1192.7(3) Å3,Z= 2,Dcalc= 2.28 g/cm3. The crystal structure was solved by direct methods and refined toR(F) = 0.0639 for 1186 unique reflections withI> 3σ(I). Rietveld refinement on powder data completely confirmed the model obtained using a single crystal. Mountainite is a phyllosilicate, representative of a new structure type. The most specific feature of the mountainite structure is aTOTblock formed by two SiO-layers [Si8O18(O,OH)2] (T-layers) and zig-zag columns of edge-sharing CaO5(H2O) octahedra sandwiched between them (O-layer). K cations occupy 10-fold polyhedra and are located between the columns of Ca-centered octahedra. The interlayer space between the neighboringTOTblocks is filled by Na cations and H2O molecules. The crystal-chemical formula is: KNa2Ca2{Si8O18[O(OH)]} · 6 H2O, the simplified formula is: KNa2Ca2Si8O19(OH) · 6 H2O.
Relationship Between Human Periodontitis and Type 2 Diabetes at a Genomic Level: A Data‐Mining Study
Authors: Covani Ugo , Marconcini Simone , Derchi Giacomo , Barone Antonio , Giacomelli Luca
Published: August 2009

Background: The leader gene approach is a data‐mining method based on the systematic search for the genes involved in a specific process and their ranking according to the interconnections with the other genes identified. The application of this algorithm to human periodontitis gave promising results. The present study used this algorithm to formulate new hypotheses about the association between periodontitis and type 2 diabetes.

Methods: The genes involved in a given process were identified via interrelated queries of several databases. The interactions among such genes were mapped and given a significance score. The weighted number of links (sum of weighted scores for every interaction in which a gene is involved) was calculated for each gene. Genes were clustered according to this parameter; those in the highest cluster were termed leader genes. This algorithm was applied to diabetes and sinusitis. Sinusitis was chosen as a control because it is an inflammatory infectious disease like periodontitis. The results were compared to those previously calculated for periodontitis.

Results: Periodontitis and diabetes share four leader genes; all leader genes are linked in a complex map of interactions. Periodontitis and sinusitis share no leader genes; no interactions were identified.

Conclusions: Even with the limitations of ab initio analyses, these theoretical results might suggest the existence of some common genomic pathways between periodontitis and type 2 diabetes, despite the different pathogenesis of these diseases. In particular, the shared leader genes could have an important role in this relationship, which may be investigated further with targeted experimentation.
Retention of Lysine in Foods Processed with Microwave and Conventional Heating
Authors: S Supreetha , Tiku Purnima Kaul , Prakash Jamuna
Published: August 2009

The effect of moist and dry heat processing on lysine content of selected foods was investigated. Two moist heat (open and closed vessel) and dry heat (microwave and hot air oven) methods were chosen for processing samples from cereal, oilseed and pulse groups with whey protein concentrate as reference sample. Unheated samples served as controls. The samples were analysed for protein content, available lysine by fluorodinitrobenzene method and for in vitro protein digestibility (IVPD). Results indicated that in moist heat-treated samples lysine retention was between 69  83%. Dry heat treatment resulted in a greater loss of lysine, which was proportional to the degree of heating. The retention of lysine in dry heat-treated samples ranged from 31 to 65 %. All heated samples had higher digestibility than their raw controls. In between methods of heating, the IVPD of dry heat-treated samples were slightly lower than moist heat-treated samples. It can be concluded that heat treatments increase the in vitro digestibility of proteins but lysine content was affected adversely.
Study of the Rheological Parameters of Honey Using the Mitschka Method
Authors: Haminiuk Charles Windson Isidoro , Maciel Giselle M. , Plata-Oviedo Manuel Salvador Vicente , Quenehenn Alessandra , Scheer Agnes P
Published: August 2009

In this work the rheological behavior of two varieties of honey were evaluated using a Brookfield viscometer R.V.T in a temperature range of 5-20°C. In order to interpret the experimental results in terms of viscosity, the torque-speed data and scale readings were converted into shear stress-shear rate relations using numerical conversion values proposed by Mitschka. This method offers excellent potential for quality control testing in the food industry. Samples exhibited Newtonian behavior and the temperature effect on the viscosity followed an Arrhenius-type relationship.
Production of Cellulolytic Enzymes by Anaerobic Fungi Cultivated in Different Conditions
Authors: Eugênia Castro Bravo-Martins Claudia , Jorge Hernán Castro-Gómez Raúl , Sarrouh Boutros F , Silvério da Silva Silvio
Published: August 2009

The present paper studies the influence of different nutrients for the production of two cellulolytic enzymes: endo beta-1.4 glucanase and exo beta- 1.4 glucanase by anaerobic fungi taken from cow rumen, that were fed a diet of corn silage and Brachiaria decumbens grass hay. During the enzymatic degradation assays, it was observed that the addition of some essential nutrients in the formulation of the culture medium contributed positively in the cellulolytic enzyme production, with exception of riboflavin. Such results contributed in the establishment of an effective method for the evaluation of enzymatic activities in anaerobic fibrolytic fungi. In this work, nutrients added to enrich the culture medium have successfully proven that they can be used as inoculating agents (inductors) in diets rich in ensilage with law nutritive value.
Identifying Middlewares for Mashup Personal Learning Environments
Authors: Fiaidhi Jinan , Mohammed Sabah , Chamarette Lyle , Thomas David
Published: August 2009

The common understanding of e-learning has shifted over the last decade from the traditional learning objects portals to learning paradigms that enforces constructivism, discovery learning and social collaboration. Such type of learning takes place outside the formal academic settings (e.g., seminars or lectures) where a learning environment is created by using some kind of web application mashup tools. The use of these mashup tools moves the learning environment further away from being a monolithic platform towards providing an open set of learning tools, an unrestricted number of actors, and an open corpus of artifacts, either pre-existing or created by the learning process – freely combinable and utilizable by learners within their learning activities. However, collaboration, mashup and contextualization can only be supported through services, which can be created and modified dynamically based on middlewares to suit the current needs and situations of learners. This article identifies middlewares suitable for creating effective personal learning environment based on Web 2.0 mashup tools. This article also proposed a general framework for constructing such personal learning environments based on Ambient Learning realized by learning agents and the use of Enterprise Mashup servers.
Amperometric Hydrogen Peroxide Biosensor Based on Immobilization of Hemoglobin on a Glassy Carbon Electrode Modified with Fe3O4/Chitosan Core-Shell Microspheres
Authors: Tan Xue-Cai , Zhang Jin-Lei , Tan Sheng-Wei , Zhao Dan-Dan , Huang Zen-Wei , Mi Yan , Huang Zai-Yin
Published: August 2009

Novel magnetic Fe3O4/chitosan (CS) microspheres were prepared using magnetic Fe3O4 nanoparticles and the natural macromolecule chitosan. Then, using an easy and effective hemoglobin (Hb) immobilization method, an innovative biosensor with a Fe3O4/CS-Hb-Fe3O4/CS “sandwich” configuration was constructed. This biosensor had a fast (less than 10 s) response to H2O2 and excellent linear relationships were obtained in the concentration range of 5.0 × 10-5 to 1.8 × 10-3 M and 1.8 × 10-3 to 6.8 × 10-3 M with a detection limit of 4.0 × 10-6 M (s/n = 3) under the optimum conditions. The apparent Michaelis-Menten constant Km was 0.29 mM and it showed the excellent biological activity of the fixed Hb. Moreover, the biosensor had long-time stability and good reproducibility. The method was used to determine H2O2 concentration in real samples.
Fabrication and Performance of MEMS-Based Pressure Sensor Packages Using Patterned Ultra-Thick Photoresists
Authors: Chen Lung-Tai , Chang Jin-Sheng , Hsu Chung-Yi , Cheng Wood-Hi
Published: August 2009

A novel plastic packaging of a piezoresistive pressure sensor using a patterned ultra-thick photoresist is experimentally and theoretically investigated. Two pressure sensor packages of the sacrifice-replacement and dam-ring type were used in this study. The characteristics of the packaged pressure sensors were investigated by using a finite-element (FE) model and experimental measurements. The results show that the thermal signal drift of the packaged pressure sensor with a small sensing-channel opening or with a thin silicon membrane for the dam-ring approach had a high packaging induced thermal stress, leading to a high temperature coefficient of span (TCO) response of -0.19% span/°C. The results also show that the thermal signal drift of the packaged pressure sensors with a large sensing-channel opening for sacrifice-replacement approach significantly reduced packaging induced thermal stress, and hence a low TCO response of -0.065% span/°C. However, the packaged pressure sensors of both the sacrifice-replacement and dam-ring type still met the specification -0.2% span/°C of the unpackaged pressure sensor. In addition, the size of proposed packages was 4 × 4 × 1.5 mm3 which was about seven times less than the commercialized packages. With the same packaging requirement, the proposed packaging approaches may provide an adequate solution for use in other open-cavity sensors, such as gas sensors, image sensors, and humidity sensors.
Efficient Risk Set Sampling when a Time-dependent Exposure Is Present
Authors: Beyersmann J. , Gastmeier P. , Schumacher M. , Wolkewitz M.
Published: August 2009

Objectives: The impact of time-dependent exposures on the time until study endpoint may correctly be analyzed with data of a full cohort. Ignoring the time-dependent nature of these exposures leads to time-dependent bias. Matching for time to exposure is often applied to take the time-dependency into account, but prefixed sets of exposed and unexposed may still create bias. This approach is attractive since a subcohort would also save resources, especially when exposure and outcome data are only available in the full cohort but further covariate information is required. The first objective is to show to which extent matching for time to exposure yields biased results. Secondly, exposure density sampling is introduced and explored.

Methods: To evaluate how both sampling methods perform, they are compared to the correct method as well as to the approach in which the time-dependent nature of the exposure is ignored. Real data of the SIR-3 study (Germany, 2000–2001) and a simulation study are used.

Results: Simulations show that matching may reduce the time-dependent bias but still there is a bias. The matching bias decreases if fewer patients are exposed. Exposure density sampling yields unbiased results.

Conclusions: Results from studies in which matching for time to exposure was applied are only tolerable for rare exposures. Whenever subcohorting is the intention in order to save resources, exposure density sampling should be preferred instead.
The Human Ecology of Malaria in a Highland Region of South-West Kenya
Authors: Herbst S. , Kistemann T. , Githinji S.
Published: August 2009

Objective: This study assessed interactions between human beings and their immediate micro-ecological environment with regard to malaria transmission at the household level.

Methods: Malaria cases and their controls were sampled from a local health care facility. A spot check of potential risk factors for malaria around the subjects’ dwelling places was done. A standardized questionnaire was administered to investigate human behavior that could lead to increased risk of malaria.

Results: Outdoor activities at night, living in houses with eaves, keeping cattle close to human dwellings and presence of stagnant water around the homesteads were associated with increased risk of malaria.

Conclusion: Living in houses with open eaves and being out at night were found to influence malaria incidences at household level.
A REVIEW FOR GELATIN USED FOR ARTIFICIAL NERVE AND BONE IMPLANTS — 10-YEAR RETROSPECTION
Authors: Chen Yueh-Sheng , Kuo Shyh-Ming , Yao Chun-Hsu
Published: August 2009

In the past 10 years, our group has successfully used the gelatin, cross-linked by different cross-linking agents, to serve in grafts for peripheral nerve and bone repair. In this review, we will introduce what we have done and share our experience with investigators who are interested in the usage of gelatin for artificial nerve and bone implants.
USING POROUS POLYETHYLENE IMPLANT FOR MAXILLOFACIAL BONY RECONSTRUCTION — A GENERAL INTRODUCTION AND CASE REPORT OF A COMPLICATION
Authors: Hsieh Thomas Mon-Hsian , Lee Chao-Hsiang , Tang Yueh-Bih , Chiang I-Jen , Wong Jau-Min
Published: August 2009

Reconstruction of facial defect is always a challenging task for plastic surgeons. Using either autogenous tissue or alloplastic material has its own merits and demerits and the decision making depends not only on the experience of the surgeon but also on the selection of the patients.

Alloplastic implant made of high-density porous polyethylene has been widely used in craniofacial reconstruction in recent years. It shows long-term stability, high tensile strength, and minimal tissue reaction. Its unique porous system facilitates tissue ingrowth, which enhances the implant fixation, therefore, it decreases the chance of migration, extrusion, and capsule formation.

Here we presented our experience of using porous polyethylene implant in our hospital, the surgical technique used for implant insertion. Finally, a case of complication was presented to discuss the use of these implants in particular situations, such as previous irradiation.

It is concluded that implant made of porous polyethylene is an ideal material for maxillofacial reconstruction; however, careful patient selection is needed. Tissue with history of previous irradiation may have the risk of poor tissue healing. Careful assessment and more scientific and reliable methods are still being sought to solve these problems.
Case report: Upper neck pouch sign in the antenatal diagnosis of esophageal atresia
Authors: Garg Mukesh Kumar
Published: August 2009

Prenatal diagnosis of esophageal atresia remains a challenge for the imaging consultant. On antenatal USG, the finding of an absent or small stomach in the setting of polyhydramnios used to be considered suspicious of esophageal atresia. However, these findings have a low positive predictive value. The upper neck pouch sign is another sign that helps in the antenatal diagnosis of esophageal atresia. In this paper, I report a case of esophageal atresia that was diagnosed on USG at 27 weeks of gestation; the diagnosis was confirmed postnatally.
MRI in congenital duplication of urethra
Authors: Bhadury S , Parashari Umesh C , Singh Ragini , Kohli Neera
Published: August 2009

Congenital urethral duplication is a rare anomaly, with less than 200 cases described in the literature. The investigations that are usually performed are micturating cystourethrography (MCU) and retrograde urethrography (RGU), which can diagnose the presence of duplication but cannot diagnose the precise relationship of the duplicated urethra with other pelvic structures. MRI, because of the excellent tissue contrast that it provides and its multiplanar ability, can demonstrate with precision, the size, shape and position of the two urethras. We describe below a case where MRI was able to show this exquisitely.
A New Approach to Pyrrolocoumarin Derivatives by Palladium‐Catalyzed Reactions: Expedient Construction of Polycyclic Lamellarin Scaffold
Authors: Chen Lei , Xu Ming‐Hua
Published: August 2009

A new and efficient protocol for straightforward synthesis of chromeno[3,4‐b]pyrrol‐4(3H)‐one derivatives by palladium‐catalyzed sequential coupling/cyclization reactions has been developed. The key strategy relies on creation of pyrrole ring through palladium‐catalyzed intramolecular hydroamination of related acetylenic aminocoumarins. The synthetic utility of the obtained chromeno[3,4‐b]pyrrol‐4(3H)‐one product has been demonstrated by the expedient synthesis of polycyclic lamellarin scaffold in four steps. It provides a new entry to synthesis of potentially valuable lamellarin analogues.
Pyrazole Synthesis Using a Titanium‐Catalyzed Multicomponent Coupling Reaction and Synthesis of Withasomnine
Authors: Majumder Supriyo , Gipson Kevin R. , Staples Richard J. , Odom Aaron L.
Published: August 2009

The titanium‐catalyzed 3‐component coupling of an alkyne, isonitrile, and amine can be used to generate tautomers of 1,3‐diimines. These diimines produced in situ undergo cyclization with hydrazine and hydrazine derivatives in a one‐pot procedure to provide pyrazoles. Seventeen examples of pyrazoles are provided using this one‐pot, 4‐component procedure from simple starting materials. The regioselectivity of the alkyne addition can be controlled in some cases with catalyst architecture, and regioselectivity of monosubsituted hydrazines to unsymmetrical 1,3‐diimines is discussed. This multicomponent coupling strategy was applied to the synthesis of withasomnine in an efficient procedure, which gave the natural product in 24% overall yield from 4‐pentyn‐1‐ol.
Nanoparticle Supported, Magnetically Recoverable Oxodiperoxo Molybdenum Complexes: Efficient Catalysts for Selective Epoxidation Reactions
Authors: Shylesh Sankaranarayanapillai , Schweizer Julia , Demeshko Serhiy , Schünemann Volker , Ernst Stefan , Thiel Werner R.
Published: August 2009

Organic‐inorganic hybrid heterogeneous nanocatalyst systems were synthesized by covalent anchoring of oxodiperoxomolybdenum complexes [(LL)MoO(O2)2] on silica coated magnetic nanoparticles as an active, magnetically separable epoxidation catalyst.
The conversion of an organometallic compound into an intercalated thin‐layer amorphous structure
Authors: Othman M. R. , Fernando W. J. N. , Kim J.
Published: August 2009

A thin alumina‐hydrotalcite (Al‐HT) film was fabricated from the synthesized boehmite and HT sol samples. The sols were a Newtonian fluid within 12 h of the sol synthesis and pseudo‐plastic flow thereon. Co‐precipitated HT demonstrated poorly crystallized periclase and spinel structures and apparent doublet peak of hydrotalcite at 2θ = 39–44°, indicative of a disordered structure. The heated Al‐HT sample demonstrated highly amorphous structure with single hydrotalcite peak but barely observed γ‐alumina and γ‐boehmite phases. The exfoliation of the spinel, gibbsite and periclase in the Al‐HT was caused by the intercalation of boehmite into the HT layers that impeded the formation of the oxides phases. Copyright © 2009 John Wiley & Sons, Ltd.
Schallfeldsimulation mit Spiegelquellen – Eine Planungshilfe für reflexionsarme Räume
Authors: Zha Xueqin , Fuchs Helmut V.
Published: August 2009

Konventionelle Auslegungen von akustischen Freifeldräumen nach ISO 3745 sind häufig mit Risiken behaftet, weil die übliche Annahme eines Absorptionsgrades bei senkrechtem Schalleinfall von 99 % herkömmlicher faseriger oder poröser Auskleidungen von Fall zu Fall weder notwendig noch ausreichend sein kann. Es wird ein Simulationsprogramm vorgestellt, das mit der phasenrichtigen Überlagerung der Schallwellen einer realen Punkt‐ und einer Serie von Spiegelquellen arbeitet, welche die unvollständig absorbierenden Begrenzungsflächen des Raumes ersetzen. Damit werden verschiedene Einflüsse aufgezeigt, die die Freifeldeigenschaften ebenso stark beeinflussen können wie der Absorptionsgrad der Auskleidung. So lässt sich bereits in einem frühen Planungsstadium mehr Sicherheit über die Qualität eines Akustik‐Prüfstandes zur Bestimmung von Schallleistung, Spektrum und Richtcharakteristik technischer Schallquellen gewinnen.

Sound field simulation by image sources – A design tool for anechoic rooms.

Conventional designs of anechoic rooms according to ISO 3745 often bear risks since the usual assumption of an absorption coefficient at normal incidence of 99 % of traditional fibrous or porous claddings may be not necessary in one case but insufficient in another. A simulation program is presented which is based on the wave interferences of the sound from a real point source and a number of image sources which replace imperfectly absorbing bounding surfaces. Its application demonstrates various effects which can influence the free‐field characteristics to the same extent as the absorption of the cladding. By this one may gain more confidence – at an early stage of the planning process – in the quality of an acoustic test facility for the determination of sound power, spectrum and directivity of technical sound sources.
New Equipment for Laboratory Studies of Heterogeneously Catalyzed Reactive Distillation
Authors: Schmitt M. , von Harbou E. , Parada S. , Grossmann C. , Hasse H.
Published: August 2009

In this paper, novel equipment for laboratory studies of heterogeneously catalyzed reactive distillation is described. The so called D+R tray equipment consists of a combination of conventional bubble cap trays with sections that are filled with catalyst and through which the liquid flows when it passes from one distillation tray down to the next. It is designed so that the catalyst can be easily changed, and its amount can be flexibly chosen. In the present study, D+R tray equipment built in glass in the 50 mm diameter scale was investigated. The pressure drop is only slightly higher than that of a standard distillation tray alone and it allows the same fluid dynamic capacity. In order to characterize the properties of the equipment as a reactor, residence time distribution (RTD) measurements were carried out. For this purpose, the equipment was modified so that only the reactive section could be studied. Still, the RTD of the catalytic bed cannot be investigated directly. It was therefore determined based on accompanying computational fluid dynamics simulations. The RTD of the catalytic bed can be described well by a simple dispersion model with a Bodenstein number of 60–65, showing that it basically has plug flow characteristics.
Supramolecular Structure in s‐Block Metal Complexes of Sulfonated Monoazo Dyes: Discrepant Packing and Bonding Behavior of ortho‐Sulfonated Azo Dyes
Authors: Kennedy Alan R. , Andrikopoulos Prokopis C. , Arlin Jean‐Baptiste , Armstrong David R. , Duxbury Neil , Graham David V. , Kirkhouse Jennifer B. A.
Published: August 2009

The first solid‐state structures of ortho‐sulfonated monoazo dyestuffs are reported and compared to those of their para‐ and meta‐sulfonated analogues. The structures of the 16 Na, K, Cs, Mg, Ca, Sr, and Ba ortho‐sulfonated salts are found to have fewer MO3S bonds than their isomeric equivalents and this in turn means that the metal type is no longer the prime indicator of which structural type will be adopted. MO3S bonds are replaced by MOH2, MHOR and M–π interactions, apparently for steric reasons. As well as new bonding motifs, the changed dye shape also leads to new packing motifs. The simple organic/inorganic layering ubiquitous to the para‐ and meta‐sulfonated dye salt structures is replaced by variations (organic bilayers, inorganic channels), each of which correlates with a different degree of molecular planarity in the sulfonated azo dye anion.
Photochemical Activities of N‐Nitroso Carboxamides and Sulfoximides and Their Application to DNA Cleavage
Authors: Hwu Jih Ru , Huang Joseph Jen‐Tse , Tsai Fu‐Yuan , Tsay Shwu‐Chen , Hsu Ming‐Hua , Hwang Kuo Chu , Horng Jia‐Cherng , Ho Ja‐an Annie , Lin Chun‐Cheng
Published: August 2009

N‐Nitroso compounds containing benzene, fluorene or fluorenone rings were synthesized. Photolysis of these compounds with 312‐nm UV light provided the NO. species, the presence of which was corroborated by use of an EPR method and of 2‐phenyl‐4,4,5,5‐tetramethylimidazolin‐1‐oxyl 3‐oxide (PTIO) as a trapping agent. During irradiation of N‐methyl‐N‐nitroso‐9‐fluorenone carboxamide (14 c) in the absence of PTIO, it underwent decomposition followed by recombination to give the heterocyclic nitric oxide radical 15. Incorporation of intercalating moieties endowed the N‐nitroso compounds with DNA‐cleaving ability through single‐strand scission upon UV irradiation in a phosphate buffer (pH 5.0–8.0) under aerobic conditions.
Boronic Acid Functionalized Core–Satellite Composite Nanoparticles for Advanced Enrichment of Glycopeptides and Glycoproteins
Authors: Zhang Lijuan , Xu Yawei , Yao Hailiang , Xie Liqi , Yao Jun , Lu Haojie , Yang Pengyuan
Published: August 2009

A core–satellite‐structured composite material has been successfully synthesized for capturing glycosylated peptides or proteins. This novel hybrid material is composed of a silica‐coated ferrite “core” and numerous “satellites” of gold nanoparticles with lots of “anchors”. The anchor, 3‐aminophenylboronic acid, designed for capturing target molecules, is highly specific toward glycosylated species. The long organic chains bridging the gold surface and the anchors could reduce the steric hindrance among the bound molecules and suppress nonspecific bindings. Due to the excellent structure of the current material, the trap‐and‐release enrichment of glycosylated samples is quite simple, specific, and effective. Indeed, the composite nanoparticles could be used for enriching glycosylated peptides and proteins with very low concentrations, and the enriched samples can be easily separated from bulk solution by a magnet. By using this strategy, the recovery of glycopeptides and glycoproteins after enrichment were found to be 85.9 and 71.6 % separately, whereas the adsorption capacity of the composite nanoparticles was proven to be more than 79 mg of glycoproteins per gram of the material. Moreover, the new composite nanoparticles were applied to enrich glycosylated proteins from human colorectal cancer tissues for identification of N‐glycosylation sites. In all, 194 unique glycosylation sites mapped to 155 different glycoproteins have been identified, of which 165 sites (85.1 %) were newly identified.
The Influence of Surface Covers on the Performance of a Soil Vapor Extraction System
Authors: Boudouch Otmane , Ying Yu , Benadda Belkacem
Published: August 2009

This study looks at the influence of surface covers on the performance of a single pumping well system. Pilot tests were conducted on a sandy soil to determine the influence of surface confinement based upon both induced vacuum and pore gas velocity design criteria. The results demonstrate how covering the surface can significantly alter the associated air flow patterns and velocity distribution. Comparison of streamline iso‐contours obtained in covered scenarios reveals that the surface seal tended to prevent air from entering the subsurface near the extraction well and force air to be drawn from a greater distance. Calculated and measured pressure differentials, for open and semi‐confined scenarios, clearly show that adding a clay layer as a surface cover increased the vacuum induced within the soil. Pore gas velocity analysis showed that when the cover clay layer was used, the zone of capture of the soil vapor extraction system increased. The radius of influence of soil vapor extraction (SVE) systems, based on the attainment of a critical vacuum or pore gas velocity, can then be increased by including a surface seal in the design of such systems. The focus of this study is limited to air flow patterns contrasted between covered and uncovered conditions and not on the nuances of a full scale remediation implementation.
Maintenance therapy in nonsmall‐cell lung cancer
Authors: Mok Tony S. K. , Ramalingam Suresh S.
Published: August 2009

Systemic chemotherapy with platinum‐based regimens provides modest improvements in survival and quality of life for patients with advanced‐stage nonsmall‐cell lung cancer (NSCLC). Extended first‐line chemotherapy with combination regimens for more than 4 to 6 cycles is not recommended because of cumulative toxicities and lack of proven advantage in survival with the increased duration of therapy. The early use of an anticancer agent as maintenance therapy after disease stabilization or maximal response with platinum‐based regimens is, therefore, being recognized as a new treatment paradigm in NSCLC. Maintenance therapy can extend first‐line treatment and provide an acceptable balance between efficacy and toxicity. The essential prerequisites for maintenance therapy include good tolerability, ability to administer extended cycles of therapy without cumulative toxicity, and an increase in the duration of progression‐free survival. Pemetrexed has recently been shown to improve the median PFS in the maintenance setting. Molecularly targeted therapies with cytostatic properties and documented tolerability also have the potential to be effective as maintenance therapy to maintain tumor regression after an initial response to chemotherapy. Consequently, the role of erlotinib and other molecular targeted agents in this treatment setting is under active investigation in ongoing phase 3 trials. This could potentially establish a new standard on the clinical utility of molecular targeted agents as maintenance therapy for patients with advanced‐stage NSCLC. Cancer 2009. © 2009 American Cancer Society.
Benefits of diversity, communication costs, and public opinion dynamics
Authors: Aldashev Gani , Carletti Timoteo
Published: August 2009

We study the dynamics of public opinion in a model where agents change their opinions as a result of random binary encounters if the opinion difference is below their individual thresholds that evolve over time. We ground these thresholds in a simple individual cost‐benefit analysis with linear benefits of diversity and quadratic communication costs. We clarify and deepen the results of earlier continuous‐opinion dynamics models (Deffuant et al., Adv Complex Systems 2000, 3, 87–98; Weisbuch et al., Complexity 2002, 7, 55–63) and establish several new results regarding the patterns of opinions in the asymptotic state and the cluster formation time. © 2009 Wiley Periodicals, Inc. Complexity, 2009