bluuebunny/crossref_metadata_2025 huggingface dataset:
A pilot‐scale demonstration of a membrane‐based absorption‐ stripping process for removal and recovery of volatile organic compounds
Authors: Majumdar S. , Bhaumik D. , Sirkar K. K. , Simes G.
Published: April 2004

A new membrane‐based continuous absorption‐stripping process has been developed to separate gas/vapor mixtures, such as volatile organic compounds (VOCs), from a nitrogen/air stream. Two different hollow fiber membrane modules are needed in this process to remove the VOCs. In the first module, VOC‐laden nitrogen/air stream flows through the bore of the hollow fibers. A suitable absorbent liquid with a high solubility for the VOC and essentially no solubility for nitrogen/air is pumped countercurrently over the outside of the fibers. This liquid is an inert, nontoxic, and essentially nonvolatile, organic solvent. The VOCs are effectively removed from nitrogen/air to a very low level and are concentrated in the absorbent for recovery, while the absorbent is regenerated by heating and subjecting it to vacuum in a separate hollow fiber membrane module called the stripping module.

A pilot‐scale membrane‐based absorption‐stripping unit was located next to a paint spray booth at Robins Air Force Base, Warner Robins, GA. Tests were performed on slip‐streams of real‐time air emissions from scheduled intermittent painting operations, so the concentration of VOC in the exhaust air fluctuated with time. The VOC removal efficiency was determined as a function of the feed air flow rate and the absorbent (silicone oil) flow rate. Depending on the gas/liquid flow rates and the inlet VOC concentration, the process successfully removed as much as 95+% of the VOC present. The experimental results have been compared with theoretical predictions.
Process analysis via waste minimization: Using DuPont's methodology to identify process improvement opportunities
Authors: Mulholland Kenneth L. , Dyer James A.
Published: April 2004

Waste is an expense, and thus costs money. Traditional problem‐solving approaches often miss process improvement opportunities, resulting in unnecessary wastes. This leads to less profitable businesses. DuPont has developed a methodology that identifies the technologies and practices that reduce waste generation. The methodology examines the process starting with the waste streams, and works back to the source of these wastes, asking questions about how it can be eliminated or minimized. This technique asks different questions about the same process information, so new improvement opportunities are identified. This paper defines waste and waste minimization, and how it impacts chemical processes. Case studies are included that show how this approach saves money and develops ideas for improving existing processes.
Air regulatory impacts of the use of tire‐derived fuel
Authors: Karell Marc A. , Blumenthal Michael H.
Published: April 2004

As a fuel, scrap tires are an economically viable choice to supplement existing sources. In addition, policies promoting the use of scrap tires as a fuel can reduce their potential for creating environmental hazards. For example, when in stockpiles, scrap tires cause emissions of toxic compounds from arson‐caused fires, and can be a breeding ground for disease‐carrying insects. The growing number of industrial applications where scrap tires can serve as a supplemental fuel includes cement kilns, the pulp and paper industry, and utility boilers.

Over the past decade, there have been a number of emissions studies on scrap tire and tire‐derived fuel (TDF) supplemented combustion. In many cases, co‐combustion with TDF has been shown to decrease emissions. This paper summarizes how supplementing combustion with TDF affects emissions of different pollutants.

Scrap tire and TDF combustion are not currently regulated by a specific New Source Performance Standards (NSPS) or Most Achievable Control Technology (MACT) standard because they typically regulate an emission unit, not a fuel type. The United States Environmental Protection Agency (EPA) is currently debating how to regulate facilities that supplement their combustion with scrap tires. This paper discusses some of those options.
Destruction of benzene with non‐thermal plasma in dielectric barrier discharge reactors
Authors: Cal Mark P. , Schluep Martin
Published: April 2004

Volatile organic compounds (VOCs) emitted to the atmosphere can cause adverse effects on human health and participate in photochemical smog formation reactions. Title III of the 1990 Clean Air Act Amendments (CAAA) requires that the U.S. Environmental Protection Agency (EPA) promulgate emission standards for 188 hazardous air pollutants (HAPs) associated with about 300 major source categories. Many industrial facilities throughout the U.S. will need pollution abatement systems for HAPs in order to be in compliance.

Non‐thermal plasma can be used to generate gas‐phase free radicals (O(1D), O(3P), OH•) at low temperature (293 K), which can then be used to destroy pollutants, such as benzene. The destruction of benzene was examined in planar dielectric barrier discharge plasma reactors as a function of applied voltage, benzene concentration, residence time and relative humidity. Near complete destruction of benzene (> 99%) was achieved in both wet and dry gas streams.
Absorption of H2S in NaOCl caustic aqueous solution
Authors: Chen Luke , Huang James , Yang Chen‐Lu
Published: April 2004

Pilot plant experimental data were collected to study the feasibility of H2S removal from air streams utilizing aqueous solutions. Solutions of NaOCl/NaOH were tested in a packed bed scrubber and found to be effective. An efficiency of 99.2% H2S removal was achieved at a gas flow rate of 790 lb/f2 ‐hr and liquid‐gas ratio of 5.06. Sodium hydroxide was found to be the active ingredient in the absorption process. A minimum alkalinity of pH 11 in the scrubbing solution was required for the H2S to be efficiently absorbed in the packed bed scrubber. For gas flow rates up to 2,100 lb/f2 hr, the height of a transfer unit (HTU) varied from 1.8 ft to 2 ft with different proportions of NaOCl and NaOH in the solution.
High VOC loadings in multiple bed biofilters: Petroleum and industrial applications
Authors: Stewart William C. , Barton Tracy Ashlock , Thom Randall R.
Published: April 2004

To meet the demands of existing and upcoming Federal air regulations more cost‐effective alternative technologies a re needed. Bio‐Reaction Industries, Inc. (BRI) has developed a patented, modular, high‐rate, vapor‐phase biofilter that has provided such a solution for a major oil company for the past four years. This compact system has adsorbed and digested high VOC surge concentrations (over 90,000 ppmv) from a glycol dehydrator in a high CO2, corrosive environment. The article presents system design changes, operation/maintenance costs, process economics and performance data. The system's capabilities for a variety of low flow (≈ 10 cfm) petroleum/natural gas process and storage tank vents will also be covered.

In addition, a higher flow system with a new bed design has undergone extensive research and development. Performance results for the system when installed at a paint manufacturing facility will be briefly described. An excellent and up‐to‐date compendium on vapor phase biofilters has recently been published by Devinny, Deshusses and Webster [1], and should be referred to for an in‐depth analysis of the technology.
Removing volatile organic compound (VOC) emissions from a printed circuit board manufacturing facility using pilot‐ and commercial‐scale biofilters
Authors: Shareefdeen Zarook , Herner Brian , Webb Derek , Polenek Sophia , Wilson Steve
Published: April 2004

This paper describes a new application of biofiltration technology to treat emissions from a printed circuit board manufacturing facility. Volatile organic compounds (VOCs), primarily Propylene Glycol Monomethyl Ether Acetate (PGMEA), di‐ Propylene Glycol Monomethyl Ether (di‐PGME), and 1‐3‐5 triazine‐2‐4‐6 triamine, are emitted during solder masking and drying of printed circuit boards. These VOCs are odorous and, hence, require treatment prior to discharge. Recently, based on data from a laboratory‐pilot biofiltration study, a 7,500 cfm capacity commercial biofilter (BASYS™) system was installed to treat odorous VOCs at a printed circuit board facility located in the Greater Toronto area. The biofilter system, which consists of two units, was packed with wood‐based (BIOMIX™) and inorganic (BIOSORBENS™) media, respectively. The biofilter system commenced operation in August of 2000. Air and media samples have been continuously collected and analyzed for monitoring and fine‐tuning of the biofilter (BASYS) system. As predicted from the laboratory‐pilot tests, results from the commercial system indicate that the biofilter unit, which contains propriety inorganic media, outperforms wood based media. While completely eliminating targeted odorous compounds such as PGMEA, the biofilter system is also shown to remove non‐target VOCs.
Performance of a full‐scale biotrickling filter treating H2S at a gas contact time of 1.6 to 2.2 seconds
Authors: Gabriel David , Deshusses Marc A.
Published: April 2004

Emission of objectionable odors is a major problem for wastewater treatment and other processing facilities. Biological treatment is a promising alternative to conventional control methods, such as chemical scrubbing, but historically, biotreatment has always required significantly larger reactor volumes than chemical scrubbers.

In this paper, we present several aspects of the operation and performance of a chemical scrubber, retrofitted to operate as a biotrickling filter treating 16,000 m3 h−1 of foul air with the original gas contact time of 1.6 to 2.2 seconds. In continuous operation for more than a year, the biotrickling filter has shown stable performance and robust behavior for H2S treatment, with pollutant removal performance comparable to using a chemical scrubber. Reclaimed water was used as a nutrient source for the process, and to maintain the pH in the biotrickling filter between 1.5 and 2.2. At a gas contact time of 1.6 seconds, H2S removal was in excess of 95% for sustained inlet H2S concentrations as high as 30 ppmv. This corresponds to volumetric elimination rates of 95 to 105 g H2S m−3 h−1. Efficiencies of about 90% were observed under transient conditions at 2.2 seconds gas contact time for inlet concentration peaks up to 60 ppmv. The biotrickling filter also removed significant amounts of reduced sulfur compounds, ammonia, and volatile organic compounds present in traces in the air, which is important in practical applications.

Selected experiments, such as intermittent trickling operation and a one‐month operation period at neutral pH, are also presented. Results indicate that the intermittent trickling operation does not have a significant effect on H2S removal. However, when operated at neutral pH, biotrickling filter performance clearly decreased, probably due to an excessive chlorine supply to the reactor through the make‐up water. The study demonstrates that biotrickling filters can replace chemical scrubbers as a safer, more economical technique for odor control.
P2X3 receptor localizes into lipid rafts in neuronal cells
Authors: Vacca Fabrizio , Amadio Susanna , Sancesario Giuseppe , Bernardi Giorgio , Volonté Cinzia
Published: April 2004

P2X receptors are a family of seven (P2X1–7) cation channels gated by extracellular ATP, widely expressed in neurons and nonneuronal cells. Lipid rafts are cholesterol/sphingolipid‐rich membrane domains, involved in many cellular processes, including transmembrane receptor signaling, vesicle traffic, and protein sorting. We provide direct biochemical evidence that P2X3 receptor localizes into lipid rafts, in primary cultures of cerebellar granule neurons as well as in brain and dorsal root ganglia extracts. We show that P2X3 exhibits all the characteristics distinctive of a protein associated with lipid rafts. These characteristics include resistance to detergent extraction at 4°C, solubility after extraction of cholesterol from membranes with either saponin or methyl‐β‐cyclodextrin, and partitioning to low buoyant density fractions after sucrose gradient centrifugation in both detergent‐containing and detergent‐free conditions. Furthermore, P2X3 localizes in raft‐containing fractions in transiently transfected SH‐SY5Y neuroblastoma cells. The present finding contributes to the characterization of the functional localization of P2X3 in neurons and provides a novel potential mechanism for correct targeting and dynamic activation of this receptor. © 2004 Wiley‐Liss, Inc.
Assessing the nature of psychological contracts: a validation of six dimensions
Authors: Sels Luc , Janssens Maddy , Van Den Brande Inge
Published: April 2004

The purpose of this study is to develop a feature‐oriented assessment of psychological contracts, an underdeveloped approach to psychological contracts. Relying on theoretical frameworks in psychological contract research, industrial relations studies, and a cross‐national study on psychological contracts, we identify six dimensions that capture the nature of psychological contracts: tangibility, scope, stability, time frame, exchange symmetry, and contract level. We validate this expanded conceptualization of psychological contracts by developing a nomological network and testing it in a large, representative sample of 1106 employees. The results indicate the significance of formal contract characteristics and HR practices as two antecedents shaping the nature of psychological contracts. In addition, the hypothesized relationships between the three dimensions of time frame, exchange symmetry, and contract level with affective commitment are confirmed as well as the relationships between tangibility, scope and flexibility with personal control. The results further indicate the importance of assessing both employer and employee obligations given the differential effect of the contract makers. Copyright © 2004 John Wiley & Sons, Ltd.
Career communities: a preliminary exploration of member‐defined career support structures
Authors: Parker Polly , Arthur Michael B. , Inkson Kerr
Published: April 2004

This paper explores the concept of career communities: social structures that provide career support and frequently transcend the boundaries of any single organization. The theoretical background notes the convergence of a number of different perspectives from both career development and organization studies, pertaining to the social contextualization of careers. The methodology involved eliciting expressions of the (individual) subjective career from the members of three potential career communities, and then exploring (communal) inter‐subjective interpretations in focus groups. Our results suggest that career communities typically involve a hybrid of types rather than any one pure type. Preliminary support is found for the view that career communities facilitate career support, sensemaking and learning. The results invite further research into career communities and have implications for organizational behavior and human resource management, suggesting greater appreciation of the extra‐organizational as well as intra‐organizational communities in which careers develop. Copyright © 2004 John Wiley & Sons, Ltd.
Ascites after liver transplantation—A mystery
Authors: Stewart Charmaine A. , Wertheim Jason , Olthoff Kim , Furth Emma E. , Brensinger Colleen , Markman James , Shaked Abraham
Published: April 2004

Ascites after liver transplantation, although uncommon, presents a serious clinical dilemma. The hemodynamic changes that support the development of ascites before liver transplantation are resolved after transplant; therefore, persistent ascites (PA) after liver transplantation is unexpected and poorly characterized. The aim of this study was to define the clinical factors associated with PA after liver transplantation. This was a retrospective case-control analysis of patients who underwent liver transplantation at the University of Pennsylvania. PA occurring for more than 3 months after liver transplantation was confirmed by imaging studies. PA was correlated with multiple recipient and donor variables, including etiology of liver disease, preoperative ascites, prior portosystemic shunt (PS), donor age, and cold ischemic (CI) time. There were 2 groups: group 1, cases with PA transplanted from November 1990 to July 2001, and group 2, consecutive, control subjects who underwent liver transplantation between September 1999 and December 2001. Both groups were followed to censoring, May 2002, or death. Twenty-five from group 1 had ascites after liver transplantation after a median follow-up of 2.6 years. In group 1 vs group 2 (n = 106), there was a male predominance 80% vs 61% (P = .10) with similar age 52 years; chronic hepatitis C virus (HCV) was diagnosed in 88% vs 44% (P < .0001); preoperative ascites and ascites refractory to treatment were more prevalent in group 1 (P = .0004 and P =.02, respectively), and CI was higher in group 1, (8.5 hours vs 6.3 hours, P = .002). Eight of the 25 (group 1) had portal hypertension with median portosystemic gradient 16.5 mm Hg (range, 16-24). PS was performed in 7 of 25 cases, which resulted in partial resolution of ascites. The development of PA after liver transplantation is multifactorial; HCV, refractory ascites before liver transplantation, and prolonged CI contribute to PA after liver transplantation. (Liver Transpl 2004;10:654-660.)
Hepatitis C recurrence is not associated with allograft steatosis within the first year after liver transplantation
Authors: Machicao Victor I. , Krishna Murli , Bonatti Hugo , Aqel Bashar A. , Nguyen Justin H. , Weigand Stephen D. , Rosser Barry G. , Hughes Christopher , Dickson Rolland C.
Published: April 2004

The natural history of allograft steatosis in hepatitis C (HCV)-infected patients after liver transplantation (LT) is poorly understood. The aim of our study was to determine the relationship of allograft steatosis to HCV recurrence after LT. All patients undergoing LT at our center from March 1998 to December 2001 were included in the study. Explanted liver tissue and liver biopsies performed at 1 week, 4 months, and 12 months were scored for degree of allograft steatosis (0-4), fibrosis (0-6), and modified histological activity index (0-18). One hundred sixty-seven HCV and 235 non-HCV-infected patients (control group) underwent LT. Of these patients, 122 HCV and 154 non-HCV patients had a viable graft at 1 year and were analyzed. Allograft steatosis was present in 40% of HCV patients at 4 months and 36% at 1 year. The incidence of allograft steatosis after LT was similar in HCV-infected and non-HCV-infected patients (P not significant). Age of the donor (P = .041), or higher recipient body mass index (BMI) at the time of LT (P = .015) or at 12 months after LT (P = .041) predicted a higher degree of allograft steatosis at 12 months in the HCV group. Degree of allograft steatosis was not associated with higher fibrosis or necroinflammatory score. In conclusion, there is a similar high incidence of allograft steatosis in HCV and non-HCV-infected patients after LT. A high BMI of the HCV-infected recipient is the best predictor for high degree of allograft steatosis after LT. Allograft steatosis does not predict the severity of HCV recurrence in the first 12 months after LT. (Liver Transpl 2004;10:599-606.)
Prediction of sustained virological response in liver transplant recipients with recurrent hepatitis C virus following combination pegylated interferon alfa-2b and ribavirin therapy using tissue hepatitis C virus reverse transcriptase polymerase chain reaction testing
Authors: Neff Guy W. , O’Brien Christopher B. , Cirocco Robert , Montalbano Marzia , de Medina Maria , Ruiz Phillip , Khaled Amr S. , Bejarano Pablo A. , Safdar Kamran , Hill Mary A. , Tzakis Andreas G. , Schiff Eugene R.
Published: April 2004

The optimal duration of therapy for pegylated interferon combined with ribavirin in recurrent Hepatitis C virus (HCV) following liver transplantation is not known. We wanted to determine if testing for HCV in liver tissue by reverse transcriptase polymerase chain reaction (RT-PCR) was superior in predicting sustained virological response (SVR) in comparison to standard HCV ribonucleic acid (RNA) detection in the serum. All recipients received combination pegylated alpha-2b interferon (1.5 mcg / kg) and ribavirin (200-600mg / d) therapy for at least 48 weeks of therapy and were found to have nondetectable HCV RNA by PCR serum testing at the end of therapy. Sustained virological response (SVR) was defined as nondetectable serum HCV RNA at 6 months post treatment withdrawal. Ten liver transplant recipients were included in the study; mean time from transplantation was 29.2 months. All had nondetectable serum HCV RNA by RT-PCR. In hepatic tissue 7/10 patients HCV RNA was found to be positive by RT-PCR while 3/10 had nondetectable HCV RNA in their liver by RT-PCR. SVR was attained in all 3/10 that were hepatic tissue HCV PCR negative after 12 months of combination therapy. In conclusion, direct detection of HCV RNA by RT-PCR of liver tissue appears to more effectively predict SVR following pegylated interferon and ribavirin therapy than the conventional use of serum. (Liver Transpl 2004;10:595-598.)
New national liver transplant allocation policy: Is the regional review board process fair?†
Authors: Voigt Michael D. , Zimmerman Bridget , Katz Daniel A. , Rayhill Stephen C.
Published: April 2004

Experienced transplant professionals may predict mortality better, in highly selected cirrhotic patients referred for accelerated listing to regional review boards, than the (Pediatric) Model for End-Stage Liver Disease score. However, these requests are often denied. We wished to establish if (1) such denials increase mortality and (2) referring physicians predict mortality better than the score. We analyzed 1,965 non-status 1 requests made between February and November 2002 from the United Network for Organ Sharing (UNOS) national scientific registry. Kaplan-Meier survival and time to transplant were compared between denied and approved patients. Cox proportional hazards analysis was used to establish if referring physicians predicted mortality better than the score. More requests were denied for patients with nonsanctioned conditions (45.7%) than for those with sanctioned conditions (13.3%); P less than .0001). Fewer patients denied accelerated listing had a transplant (46.6% vs. 63.8%; P < .0001); time to transplant was similar (P = .2). However, nonsanctioned cirrhotic cases denied accelerated listing had lower mortality than approved cases (P < .04). Referring physicians predict mortality poorly (P = .23), whereas the Model for End-Stage Liver Disease (MELD)-Pediatric Model for End-Stage Liver Disease (PELD) score was highly predictive (P = .0003). In conclusion, regional review boards are fair and can accurately distinguish high- from low-risk patients. Denying requests does not increase mortality. The MELD-PELD score remains the best predictor of mortality, but the review board process adds additional information. Referring physicians predict patient mortality poorly. (Liver Transpl 2004;10:666-674)
Immunosuppressive and postoperative effects of orthotopic liver transplantation on bone metabolism
Authors: Guichelaar Maureen M. J. , Malinchoc Michael , Sibonga Jean , Clarke Bart L. , Hay Eileen J.
Published: April 2004

Bone loss occurs early after orthotopic liver transplantation (OLT) in all liver transplant recipients and leads to postoperative fractures, especially in cholestatic patients with the lowest bone mass. Little is known about the underlying changes in bone metabolism after OLT or about the etiology of these changes. Histomorphometric analysis of bone biopsies, a method that allows assessment of bone volume, resorption, and formation, has shown improved bone metabolism at 4 months after OLT. It has further suggested that accelerated posttransplant bone loss occurs in the first 1-2 months after OLT, probably by an additional insult to bone formation. This study attempts to correlate the histomorphometric bone changes in paired bone biopsies (OLT and 4 months after OLT) of 33 patients undergoing OLT for chronic cholestatic liver disease with the many clinical and biochemical changes in these patients over the same period. Cumulative steroid dosage early after OLT is shown to be important, presumably by decreasing bone formation rates. The actual effect of calcineurin inhibitors on this early phase of bone loss is less clear, although posttransplant histomorphometric findings suggest that tacrolimus-treated patients have an earlier recovery of bone metabolism and trabecular structure compared with cyclosporine patients. Other factors important in the recovery of bone metabolism after the early phase of bone loss are recovery of liver and gonadal function and better calcium balance. (Liver Transpl 2004;10:638-647.)
Differential protein profiling in renal‐cell carcinoma
Authors: Shi Ting , Dong Fan , Liou Louis S. , Duan Zhong‐Hui , Novick Andrew C. , DiDonato Joseph A.
Published: April 2004

Characterizing the alterations of protein expression in cancer cells can be very useful in providing insight into the changes in the functional pathways and thus the fundamental mechanisms of cancer development at the molecular level. In this study, we profiled protein expressions in eleven pairs of primary cell cultures derived from renal‐cell carcinoma (RCC) tissues and patient‐matched normal kidney tissues utilizing two‐dimensional polyacrylamide gel electrophoresis (2‐D PAGE). Together with the immunoblot analysis of proteins from the RCC tissues, the study also demonstrated that the alterations of protein expression observed in RCC primary cell cultures reflected those observed in the original RCC tissues. We analyzed the expression profiles and identified proteins differentially expressed in RCC primary cell cultures by 2‐D PAGE and mass spectrometry (MS). We found sixteen proteins were overexpressed and seven proteins underexpressed in RCC. The deregulated expressions of proteins include those involved in metabolism, cellular morphology, heat shock response, cell growth, etc. Overexpression of three proteins, αβ‐crystallin, manganese superoxide dismutase (MnSOD), and annexin IV, most commonly observed in primary RCC cell cultures, were also observed by immunoblot analysis of proteins from the RCC tissues from which the primary cell cultures were derived. Semi‐quantitative reverse transcription (RT)‐polymerase chain reaction (PCR) analysis revealed the direct correlation between deregulated gene expression and the corresponding protein abundance in two of the three most commonly upregulated proteins we found in RCC. © 2004 Wiley‐Liss, Inc.
Modulation of gene expression by hypoxia in human umbilical cord vein endothelial cells: A transcriptomic and proteomic study
Authors: Scheurer Simone B. , Raybak Jascha N. , Rösli Christoph , Neri Dario , Elia Giuliano
Published: April 2004

Hypoxia is a characteristic feature of many human pathologies, including cancer. The sustained proliferation rate of tumor cells leads to alterations of the tumor microenvironment, that progressively becomes more acidic, nutrient‐deprived, and hypoxic. The reduced partial pressure of oxygen triggers the onset of an adaptive response, aimed at increasing the local oxygen concentration by several complementary actions. Although directly exposed to the blood stream, endothelial cells lining the vascular lumen in tumors also can be exposed to hypoxia and therefore can contribute to the onset of the adaptive response that leads to tumor angiogenesis. Aiming at getting a detailed insight into the oxygen‐dependent regulation of the transcriptional program of vascular endothelial cells and at identifying new relevant markers that may be used as targets for therapeutic intervention in tumor angiogenesis, we have performed a broad‐range transcriptomic analysis, using the Affymetrix HG‐U133A Gene Chips, of mRNA expression levels in human umbilical cord vein endothelial cells (HUVEC), exposed in vitro to hypoxia for different time periods. The transcriptomic analysis was complemented by a semiquantitative reverse transcriptase‐polymerase chain reaction (RT‐PCR) analysis of mRNA levels and alternative splicing for some selected extracellular matrix protein genes, and by a proteomic analysis, using two‐dimensional polyacrylamide gel electrophoresis (2‐D PAGE) and tandem mass spectrometry for protein separation and identification, of hypoxic and normoxic HUVEC whole‐cell lysates and subcellular fractions. Our analysis confirmed previous findings on genes whose expression is regulated by oxygen concentration but also identified new genes (e.g., CXCR4, claudin 3, CD24, tetranectin, Del‐1, procollagen lysyl hydroxylase 1 and 2) which are transcriptionally upregulated in hypoxic conditions.
The New Cesium Praseodymium Thiophosphate Cs3Pr5[PS4]6
Authors: Komm Theresa , Schleid Thomas
Published: April 2004

Transparent platelet‐shaped green single crystals of the title compound were obtained by the reaction of cesium bromide, praseodymium, sulfur, and red phosphorus in the molar ratio 1:2:8:2 with an excess of CsBr as flux in evacuated silica ampoules at 950 °C for fourteen days. Cs3Pr5[PS4]6 crystallizes monoclinically in the space group C2/c (a = 1627.78(7), b = 1315.09(6), c = 2110.45(9) pm, β = 103.276(5)°; Z = 4). Its crystal structure is different from all the other alkali‐metal containing ortho‐thiophosphates of the lanthanides, since it is not possible to formulate a layer containing the praseodymium centered sulfur polyhedra ([PrS8]13—, d(Pr—S) = 286 — 307 pm) and the isolated [PS4]3— tetrahedra (d(P—S) = 202 — 207 pm, ∢(S—P—S) = 104 — 106°). All these tetrahedra are edge‐sharing with the metal polyhedra to build up a framework instead. The coordination sphere of the half occupied (Cs2)+ cations (CN = 10 + 2) can be described as two six‐membered sulfur rings in chair conformation containing a “cesium‐pair” in the middle. In contrast the (Cs1)+ cations are surrounded in the not unusual configuration of tetracapped trigonal prisms (CN = 10, better 10 + 2 as well).
Election Time: Normative Implications of Temporal Properties of the Electoral Process in the United States
Authors: THOMPSON DENNIS F.
Published: April 2004

Elections take place at intervals, most citizens vote on the same day, and the electoral outcome is irrevocable until the next election. Each of these temporal properties—periodicity, simultaneity, and finality—is grounded in fundamental democratic values. Analyzing the properties shows how and why several anomalies in electoral theory and practice in the United States should be eliminated. Together the properties mark off electoral politics as a sphere that requires different and often more stringent standards than the rest of political life outside of government. Periodicity requires that the control of redistricting be independent of legislatures. Simultaneity opposes publishing the results of exit polls, expanding the use of early voting, and granting legislatures the authority to select presidential electors on their own schedule. Finality justifies more stringent regulation of campaign practices, such as electioneering ads.
Embodied meaning and negative priming
Authors: Glenberg Arthur M. , Robertson David A. , Kaschak Michael P. , Malter Alan J.
Published: April 2004

Standard models of cognition are built from abstract, amodal, arbitrary symbols, and the meanings of those symbols are given solely by their interrelations. The target article (Glenberg 1997t) argues that these models must be inadequate because meaning cannot arise from relations among abstract symbols. For cognitive representations to be meaningful they must, at the least, be grounded; but abstract symbols are difficult, if not impossible, to ground. As an alternative, the target article developed a framework in which representations are grounded in perception and action, and hence are embodied. Recent work (Glenberg & Robertson 1999; 2000; Glenberg & Kaschak 2002; Kaschak & Glenberg 2000) extends this framework to language.
Meeting Newell's other challenge: Cognitive architectures as the basis for cognitive engineering
Authors: Gray Wayne D. , Schoelles Michael J. , Myers Christopher W.
Published: April 2004

We use the Newell Test as a basis for evaluating ACT-R as an effective architecture for cognitive engineering. Of the 12 functional criteria discussed by Anderson & Lebiere (A&L), we discuss the strengths and weaknesses of ACT-R on the six that we postulate are the most relevant to cognitive engineering.
Developing a domain-general framework for cognition: What is the best approach?
Authors: McClelland James L. , Plaut David C. , Gotts Stephen J. , Maia Tiago V.
Published: April 2004

We share with Anderson & Lebiere (A&L) (and with Newell before them) the goal of developing a domain-general framework for modeling cognition, and we take seriously the issue of evaluation criteria. We advocate a more focused approach than the one reflected in Newell's criteria, based on analysis of failures as well as successes of models brought into close contact with experimental data. A&L attribute the shortcomings of our parallel-distributed processing framework to a failure to acknowledge a symbolic level of thought. Our framework does acknowledge a symbolic level, contrary to their claim. What we deny is that the symbolic level is the level at which the principles of cognitive processing should be formulated. Models cast at a symbolic level are sometimes useful as high-level approximations of the underlying mechanisms of thought. The adequacy of this approximation will continue to increase as symbolic modelers continue to incorporate principles of parallel distributed processing.
Cranial factors in neocortical evolution
Authors: O'Shea Geoffrey
Published: April 2004

Our understanding of paleoneurology can benefit through considerations of how ontogenetic patterns of skull suture ossification can limit the phylogenetic expansion of underlying brain tissue to specific regions. Additionally, the influence of biochemical, rather than biomechanical, mechanisms on skull suture morphogenesis enable a reconceptualization of the skull as an independent evolutionary system from the brain.
Conserved functional organization of the amniote telencephalic pallium
Authors: Salas Cosme , Broglio Cristina , Rodríguez Fernando
Published: April 2004

The dorsal and medial pallial formations of mammals, birds, and reptiles show overall functional striking similarities. Most of these similarities have been frequently considered examples of convergent evolution. However, a considerable amount of neurobiological comparative evidence suggests the presence of a common basic pattern of vertebrate forebrain organization. This common pattern can support functional conservation.
Neurokinin NK1 and NK3 receptors as targets for drugs to treat gastrointestinal motility disorders and pain
Authors: Sanger Gareth J
Published: April 2004

NK1 and NK3 receptors do not appear to play significant roles in normal GI functions, but both may be involved in defensive or pathological processes. NK1 receptor antagonists are antiemetic, operating via vagal sensory and motor systems, so there is a need to study their effects on other gastro‐vagal functions thought to play roles in functional bowel disorder's. Interactions between NK1 receptors and enteric nonadrenergic, noncholinergic motorneurones suggest a need to explore the role of this receptor in disrupted colonic motility. NK1 receptor antagonism does not exert consistent analgesic activity in humans, but similar studies have not been carried out against pain of GI origin, where NK1 receptors may have additional influences on mucosal inflammatory or ‘irritant’ processes. NK3 receptors mediate certain disruptions of intestinal motility. The activity may be driven by tachykinins released from intrinsic primary afferent neurones (IPANs), which induce slow EPSP activity in connecting IPANs and hence, a degree of hypersensitivity within the enteric nervous system. The same process is also proposed to increase C‐fibre sensitivity, either indirectly or directly. Thus, NK3 receptor antagonists inhibit intestinal nociception via a ‘peripheral’ mechanism that may be intestine‐specific. Studies with talnetant and other selective NK3 receptor antagonists are, therefore, revealing an exciting and novel pathway by which pathological changes in intestinal motility and nociception can be induced, suggesting a role for NK3 receptor antagonism in irritable bowel syndrome.

British Journal of Pharmacology (2004) 141, 1303–1312. doi:10.1038/sj.bjp.0705742
CRF1receptor signaling pathways are involved in stress‐related alterations of colonic function and viscerosensitivity: implications for irritable bowel syndrome
Authors: Taché Y , Martinez V , Wang L , Million M
Published: April 2004

The characterization of corticotropin releasing factor (CRF) and, more recently, the discovery of additional CRF‐related ligands, urocortin 1, urocortin 2 and urocortin 3, the cloning of two distinct CRF receptor subtypes, 1 (CRF1) and 2 (CRF2), and the development of selective CRF receptor antagonists provided new insight to unravel the mechanisms of stress. Activation of brain CRF1receptor signaling pathways is implicated in stress‐related endocrine response and the development of anxiety‐like behaviors.

Compelling evidence in rodents showed also that both central and peripheral injection of CRF and urocortin 1 mimic acute stress‐induced colonic response (stimulation of motility, transit, defecation, mucus and watery secretion, increased ionic permeability and occurrence of diarrhea) in rodents. Central CRF enhances colorectal distention‐induced visceral pain in rats. Peripheral CRF reduced pain threshold to colonic distention and increased colonic motility in humans.

Nonselective CRF1/CRF2antagonists and selective CRF1antagonists inhibit exogenous (central or peripheral) CRF‐ and acute stress‐induced activation of colonic myenteric neurons, stimulation of colonic motor function and visceral hyperalgesia while selective CRF2antagonists have no effect. None of the CRF antagonists influence basal or postprandial colonic function in nonstressed animals.

These findings implicate CRF1receptors in stress‐related stimulation of colonic function and hypersensitivity to colorectal distention. Targeting CRF1‐dependent pathways may have potential benefit against stress or anxiety‐/depression‐related functional bowel disorders.

British Journal of Pharmacology(2004)141, 1321–1330. doi:10.1038/sj.bjp.0705760
Activation and sensitisation of the vanilloid receptor: role in gastrointestinal inflammation and function
Authors: Geppetti Pierangelo , Trevisani Marcello
Published: April 2004

The exquisite specific excitatory and desensitising actions of capsaicin on a subpopulation of primary sensory neurons have been instrumental in identifying the roles of these neurons in nociception, reflex responses and neurogenic inflammation.

Structure activity studies with capsaicin‐like molecules have suggested that a ‘receptor’ should mediate the effects of capsaicin on sensory neurons. The cloning of the vanilloid receptor‐1 (VR1) has confirmed this hypothesis.

VR1 (TRPV1) belongs to the transient receptor potential (TRP) family of channels, and its activation by various xenobiotics, noxious temperature, extracellular low pH and high concentration of certain lipid derivatives results in cation influx and sensory nerve terminal excitation.

TRPV1 may dimerise or form tetramers or heteromers with PLC‐γ and TrkA or even with other TRPs. TRPV1 is markedly upregulated and/or ‘sensitised’ under inflammatory conditions via protein kinase C‐ɛ‐, cAMP‐dependent PK‐ and PLC‐γ‐dependent pathways or by exposure to dietary agents as ethanol.

TRPV1 is expressed on sensory neurons distributed in all the regions of the gastrointestinal tract in myenteric ganglia, muscle layer and mucosa. There is evidence of TRPV1 expression also in epithelial cells of the gastrointestinal tract.

High expression of TRPV1 has been detected in several inflammatory diseases of the colon and ileum, whereas neuropeptides released upon sensory nerve stimulation triggered by TRPV1 activation seem to play a role in intestinal motility disorders.

TRPV1 antagonists, which will soon be available for clinical testing, may undergo scrutiny for the treatment of inflammatory diseases of the gut.

British Journal of Pharmacology (2004) 141, 1313–1320. doi:10.1038/sj.bjp.0705768
Involvement of cannabinoid receptors in gut motility and visceral perception
Authors: Hornby Pamela J , Prouty Stephen M
Published: April 2004

From a historical perspective to the present day, all the evidence suggests that activation of cannabinoid receptors (CBRs) is beneficial for gut discomfort and pain, which are symptoms related to dysmotility and visceral perception. CBRs comprise G‐protein coupled receptors that are predominantly in enteric and central neurones (CB1R) and immune cells (CB2R). In the last decade, evidence obtained from the use of selective agonists and inverse agonists/antagonists indicates that manipulation of CB1R can alter (1) sensory processing from the gut, (2) brain integration of brain‐gut axis, (3) extrinsic control of the gut and (4) intrinsic control by the enteric nervous system. The extent to which activation of CB1R is most critical at these different levels is related to the region of the GI tract. The upper GI tract is strongly influenced by CB1R activation on central vagal pathways, whereas intestinal peristalsis can be modified by CB1R activation in the absence of extrinsic input. Actions at multiple levels make the CB1R a target for the treatment of functional bowel disorders, such as IBS. Since low‐grade inflammation may act as a trigger for occurrence of IBS, CB2R modulation could be beneficial, but there is little supporting evidence for this yet. The challenge is to accomplish CBR activation while minimizing adverse effects and abuse liabilities. Potential therapeutic strategies involve increasing signaling by endocannabinoids (EC). The pathways involved in the biosynthesis, uptake and degradation of EC provide opportunities for modulation of CB1R and some recent evidence with inhibitors of EC uptake and metabolism suggest that these could be exploited for therapeutic gain.

British Journal of Pharmacology (2004) 141, 1335–1345. doi:10.1038/sj.bjp.0705783
Human posterior auditory cortex gates novel sounds to consciousness
Authors: Jääskeläinen Iiro P. , Ahveninen Jyrki , Bonmassar Giorgio , Dale Anders M. , Ilmoniemi Risto J. , Levänen Sari , Lin Fa-Hsuan , May Patrick , Melcher Jennifer , Stufflebeam Steven , Tiitinen Hannu , Belliveau John W.
Published: April 2004

Life or death in hostile environments depends crucially on one's ability to detect and gate novel sounds to awareness, such as that of a twig cracking under the paw of a stalking predator in a noisy jungle. Two distinct auditory cortex processes have been thought to underlie this phenomenon: (
i
) attenuation of the so-called N1 response with repeated stimulation and (
ii
) elicitation of a mismatch negativity response (MMN) by changes in repetitive aspects of auditory stimulation. This division has been based on previous studies suggesting that, unlike for the N1, repetitive “standard” stimuli preceding a physically different “novel” stimulus constitute a prerequisite to MMN elicitation, and that the source loci of MMN and N1 are different. Contradicting these findings, our combined electromagnetic, hemodynamic, and psychophysical data indicate that the MMN is generated as a result of differential adaptation of anterior and posterior auditory cortex N1 sources by preceding auditory stimulation. Early (≈85 ms) neural activity within posterior auditory cortex is adapted as sound novelty decreases. This alters the center of gravity of electromagnetic N1 source activity, creating an illusory difference between N1 and MMN source loci when estimated by using equivalent current dipole fits. Further, our electroencephalography data show a robust MMN after a single standard event when the interval between two consecutive novel sounds is kept invariant. Our converging findings suggest that transient adaptation of feature-specific neurons within human posterior auditory cortex filters superfluous sounds from entering one's awareness.
Ancestral hemoglobins in
Archaea
Authors: Freitas Tracey Allen K. , Hou Shaobin , Dioum Elhadji M. , Saito Jennifer A. , Newhouse James , Gonzalez Gonzalo , Gilles-Gonzalez Marie-Alda , Alam Maqsudul
Published: April 2004

Hemoglobins are ubiquitous in
Eukarya
and
Bacteria
but, until now, have not been found in
Archaea
. A phylogenetic analysis of the recently revealed microbial family of globin-coupled heme-based sensors suggests that these sensors descended from an ancient globin-only progenitor, or a protoglobin (Pgb). Here, we report the discovery and characterization of two Pgbs from the
Archaea
:
Ap
Pgb from the obligately aerobic hyperthermophile
Aeropyrum pernix
, and
Ma
Pgb from the strictly anaerobic methanogen
Methanosarcina acetivorans
. Both
Ap
Pgb and
Ma
Pgb bind molecular oxygen, nitric oxide, and carbon monoxide by means of a heme moiety that is coordinated to the protein through the F8 histidine (histidine 120). We postulate that these archaeal globins are the ancestors of contemporary hemoglobins.
Single-molecule high-resolution imaging with photobleaching
Authors: Gordon Matthew P. , Ha Taekjip , Selvin Paul R.
Published: April 2004

Conventional light microscopy is limited in its resolving power by the Rayleigh limit to length scales on the order of 200 nm. On the other hand, spectroscopic techniques such as fluorescence resonance energy transfer cannot be used to measure distances >10 nm, leaving a “gap” in the ability of optical techniques to measure distances on the 10- to 100-nm scale. We have previously demonstrated the ability to localize single dye molecules to a precision of 1.5 nm with subsecond time resolution. Here we locate the position of two dyes and determine their separation with 5-nm precision, using the quantal photobleaching behavior of single fluorescent dye molecules. By fitting images both before and after photobleaching of one of the dyes, we may localize both dyes simultaneously and compute their separation. Hence, we have circumvented the Rayleigh limit and achieved nanometer-scale resolution. Specifically, we demonstrate the technique by measuring the distance between single fluorophores separated by 10–20 nm via attachment to the ends of double-stranded DNA molecules immobilized on a surface. In addition to bridging the gap in optical resolution, this technique may be useful for biophysical or genomic applications, including the generation of super-high-density maps of single-nucleotide polymorphisms.