bluuebunny/crossref_metadata_2025 huggingface dataset:
A miniaturized assay to quantify effects of chemicals or physical stimuli upon locust activity
Authors: HOSTE BRUNO , SAS FILIP , VANDERSMISSEN TIM , DE LOOF ARNOLD , BREUER MICHAEL , HUYBRECHTS JURGEN
Published: October 2006

Abstract
Solitary and gregarious locusts differ in many traits, such as body color, morphometrics and behavior. With respect to behavior, solitary animals shun each other, while gregarious animals seek each other's company, hence their crowding behavior. General activity, depending on the temperature, occurs throughout the day but is much lower in solitary locusts. Solitary locusts occasionally fly by night while gregarious locusts fly regularly during daytime (swarming). In search of new assays to identify substances that control or modify aspects of (phase) behavior, we designed a simple activity assay, meant to complement existing behavioral measurement tools. The general activity is reflected in the number of wall hits, that is, the number of contacts between the locust and the vertical walls of a small arena. Using this single parameter we were able to quantify differences in total activity of both nymphs and adults of isolation‐reared (solitary), regrouped‐ and crowd‐reared (gregarious) locusts under different conditions. Furthermore, we demonstrate that there are inter‐ and intra‐phase dependent differences in activities of 5th instar nymphs after injections of the three different adipokinetic hormones.
How we do it: Chemo‐electroporation in the head and neck for otherwise untreatable patients
Authors: Tijink B.M. , De Bree R. , Van Dongen G.A.M.S. , Leemans C.R.
Published: October 2006

Keypoints

• Chemo‐electroporation therapy with bleomycin is a locoregional treatment modality for head and neck and skin cancer, with the potential to preserve function.

• In our institution, chemo‐electroporation therapy is used for patients that can no longer be treated by surgery or radiotherapy, or for whom surgical treatment would be very extensive and thus declined by the patient.

• This paper describes in detail the technique of bleomycin‐electroporation therapy. The literature is reviewed and preliminary results of the clinical trial are presented.

• The main focus of the trial is to determine the safety, effectiveness, and burden of bleomycin‐electroporation therapy for the patient.

• All 17 tumours responded to therapy. Local tumour control was reached in 14 of the 17 (82.4 %) tumours.

• Based on the outcome of the clinical trial, bleomycin‐electroporation therapy has the potential to become a valuable addition to the late‐stage treatment options for patients with head and neck or skin tumours.
How we do it: Dispensing with drains in hemithyroidectomy – a feasibility study
Authors: Hopkins C. , Mansuri S. , Terry R.M.
Published: October 2006

Keypoints

• The NHS plan states that 75% of all elective surgery should be carried out as day cases, but reports confirm that we are falling well below such targets.

• The use of the harmonic scalpel in thyroidectomy in our department has facilitated faster surgery, minimal intra‐operative haemorrhage, and reduced postoperative blood loss into the drain.

• We propose that patients with small solitary nodules (<25 cm3 on preoperative ultrasound) undergoing hemithyroidectomy for diagnostic purposes are candidates for selective use of drains, or where used, early removal of the drain and same day discharge.
Is admission for epistaxis more common in Caucasian than in Asian people? A preliminary study
Authors: Daniel M. , Jaberoo M.C. , Stead R.E. , Reddy V.M. , Moir A.A.
Published: October 2006

Objectives:  Epistaxis is a common ENT complaint. Although casual observation suggested that it is more common in Caucasian, compared with Asian people, a literature search failed to find any studies investigating ethnicity and epistaxis. The aim of this study was to identify any differences in emergency admission rates for epistaxis between Asian and Caucasian people.

Design:  Retrospective observational study using hospital computerised data (HISS).

Setting:  Large University Hospital accepting ENT emergencies.

Participants:  All Asian and Caucasian patients admitted under ENT care as an emergency (1 January 2000 to 30 November 2005), split into two groups: one composed of epistaxis patients, the other of all other ENT emergency admissions.

Main outcomes measures:  The proportions of Asian and Caucasian patients among the two patient groups, either epistaxis admissions or other ENT emergency admissions.

Results:  The proportions of Asian and Caucasian patients in the group admitted with emergency epistaxis were 7.1% (100/1410) and 92.9% (1310/1410) respectively. However, the proportions of Asian and Caucasian patients in the group composed of any other ENT emergency were 13.2% (729/5515) and 86.8% (4786/5515), respectively (chi‐squared P < 0.01).

Conclusions:  Caucasian people form an unexpectedly large, and Asians a smaller proportion of emergency epistaxis admissions. The possibility of an ethnic risk factor for epistaxis warrants further investigation.
Exploring the relationship between severity of dysphonia and voice‐related quality of life
Authors: Jones S.M. , Carding P.N. , Drinnan M.J.
Published: October 2006

Objectives:  To explore whether severity and/or consistency of dysphonia are linked to voice‐related quality of life.

Design:  Cross‐sectional study.

Setting:  Specialist voice clinics, University Teaching Hospital.

Participants:  Sixty adult patients attending with a primary complaint of dysphonia. Exclusion criteria were those below 16 years of age, transexual patients and those with a persistent dysphonia of >2 years.

Main outcome measures:  Voice‐related quality of life as assessed by VoiSS.

Explanatory factors:  Severity of dysphonia as judged by perceptual ratings of voice (GRBAS); a visual analogue scale to judge best, worst and today's voice.

Results:  There was a highly significant correlation between perceptual dysphonia severity as assessed by GRBAS and the total, impairment and emotional subsets of the VoiSS questionnaire (r from 0.48 to 0.64).

There was a similar and highly significant correlation between best, worst and today's self‐rated voice and the total, impairment and emotional subsets of the VoiSS questionnaire (r from −0.40 to −0.60). However, none of the self‐rated parameters was demonstrably better at explaining the effect on quality of life.

Conclusions:  An increasingly negative effect on quality of life appears to be associated with an increase in the severity of dysphonia. Further research on the role of quality of life measures in the assessment and treatment of dysphonia would be of value.
The Three-Dimensional Structure of the Flagellar Rotor from a Clockwise-Locked Mutant of
Salmonella enterica
Serovar Typhimurium
Authors: Thomas Dennis R. , Francis Noreen R. , Xu Chen , DeRosier David J.
Published: October 2006

Three-dimensional reconstructions from electron cryomicrographs of the rotor of the flagellar motor reveal that the symmetry of individual M rings varies from 24-fold to 26-fold while that of the C rings, containing the two motor/switch proteins FliM and FliN, varies from 32-fold to 36-fold, with no apparent correlation between the symmetries of the two rings. Results from other studies provided evidence that, in addition to the transmembrane protein FliF, at least some part of the third motor/switch protein, FliG, contributes to a thickening on the face of the M ring, but there was no evidence as to whether or not any portion of FliG also contributes to the C ring. Of the four morphological features in the cross section of the C ring, the feature closest to the M ring is not present with the rotational symmetry of the rest of the C ring, but instead it has the symmetry of the M ring. We suggest that this inner feature arises from a domain of FliG. We present a hypothetical docking in which the C-terminal motor domain of FliG lies in the C ring, where it can interact intimately with FliM.
Regulation of Mercury Resistance in the Crenarchaeote
Sulfolobus solfataricus
Authors: Schelert James , Drozda Melissa , Dixit Vidula , Dillman Amanda , Blum Paul
Published: October 2006

Mercuric ion, Hg(II), inactivates generalized transcription in the crenarchaeote
Sulfolobus solfataricus
. Metal challenge simultaneously derepresses transcription of mercuric reductase (
merA
) by interacting with the archaeal transcription factor aMerR. Northern blot and primer extension analyses identified two additional Hg(II)-inducible
S. solfataricus
genes,
merH
and
merI
(SSO2690), located on either side of
merA
. Transcription initiating upstream of
merH
at promoter
merHp
was metal inducible and extended through
merA
and
merI
, producing a
merHAI
transcript. Northern analysis of a
merRA
double mutant produced by linear DNA recombination demonstrated
merHp
promoter activity was dependent on aMerR to overcome Hg(II) transcriptional inhibition. Unexpectedly, in a
merA
disruption mutant, the
merH
transcript was transiently induced after an initial period of Hg(II)-mediated transcription inhibition, indicating continued Hg(II) detoxification. Metal challenge experiments using mutants created by markerless exchange verified the identity of the MerR binding site as an inverted repeat (IR) sequence overlapping the transcription factor B binding recognition element of
merHp
. The interaction of recombinant aMerR with
merHp
DNA, studied using electrophoretic mobility shift analysis, demonstrated that complex formation was template specific and dependent on the presence of the IR sequence but insensitive to Hg(II) addition and site-specific IR mutations that relieved in vivo
merHp
repression. Despite containing a motif resembling a distant ArsR homolog, these results indicate aMerR remains continuously DNA bound to protect and coordinate Hg(II)-responsive control over
merHAI
transcription. The new genetic methods developed in this work will promote experimental studies on
S. solfataricus
and other
Crenarchaeota
.
Altered Ca2+Regulation of Yop Secretion inYersinia enterocoliticaafter DNA Adenine Methyltransferase Overproduction Is Mediated by Clp-Dependent Degradation of LcrG
Authors: Fälker Stefan , Schmidt M. Alexander , Heusipp Gerhard
Published: October 2006

DNA methylation by the DNA adenine methyltransferase (Dam) interferes with the coordinated expression of virulence functions in an increasing number of pathogens. While analyzing the effect of Dam on the virulence of the human pathogenYersinia enterocolitica, we observed type III secretion of Yop effector proteins under nonpermissive conditions. Dam alters the Ca2+regulation of Yop secretion but does not affect the temperature regulation of Yop/Ysc expression. The phenotype is different from that of classical “Ca2+-blind” mutants ofYersinia, as Dam-overproducing (DamOP) strains still translocate Yops polarly into eukaryotic cells. Although transcription of thelcrGVandyopN-tyeAoperons is slightly upregulated, LcrG is absent from lysates of DamOPbacteria, while the amounts of YopN and TyeA are not changed. We present evidence thatclpXPexpression increases after Dam overproduction and that the ClpP protease then degrades LcrG, thereby releasing a block in type III secretion. This is the first example of posttranslational regulation of type III secretion by the Clp protease and adds a new flavor to the complex regulatory mechanisms underlying the controlled release of effector proteins from bacterial cells.
Regulatory Loop between Redox Sensing of the NADH/NAD
+
Ratio by Rex (YdiH) and Oxidation of NADH by NADH Dehydrogenase Ndh in
Bacillus subtilis
Authors: Gyan Smita , Shiohira Yoshihiko , Sato Ichiro , Takeuchi Michio , Sato Tsutomu
Published: October 2006

NADH dehydrogenase is a key component of the respiratory chain. It catalyzes the oxidation of NADH by transferring electrons to ubiquinone and establishes a proton motive force across the cell membrane. The
yjlD
(renamed
ndh
) gene of
Bacillus subtilis
is predicted to encode an enzyme similar to the NADH dehydrogenase II of
Escherichia coli
, encoded by the
ndh
gene. We have shown that the
yjlC-ndh
operon is negatively regulated by YdiH (renamed Rex), a homolog of Rex in
Streptomyces coelicolor
, and a redox-sensing transcriptional regulator that responds to the NADH/NAD
+
ratio. The
ndh
gene regulates expression of the
yjlC-ndh
operon, as indicated by the fact that mutation in
ndh
causes a higher NADH/NAD
+
ratio. An in vitro study showed that Rex binds to the downstream region of the
yjlC-ndh
promoter and that NAD
+
enhances the binding of Rex to the putative Rex-binding sites in the
yjlC-ndh
operon as well as in the
cydABCD
operon. These results indicated that Rex and Ndh together form a regulatory loop which functions to prevent a large fluctuation in the NADH/NAD
+
ratio in
B. subtilis
.
A Plasmid-Borne Truncated
luxI
Homolog Controls Quorum-Sensing Systems and Extracellular Carbohydrate Production in
Methylobacterium extorquens
AM1
Authors: Penalver Carlos G. Nieto , Cantet Franck , Morin Danièle , Haras Dominique , Vorholt Julia A.
Published: October 2006

A cryptic plasmid of
Methylobacterium extorquens
AM1 was found to encode
tslI
, a truncated
luxI
homolog.
tslI
was shown to be expressed and to control transcription of the acyl-homoserine lactone (HSL) synthase gene
msaI
and thus, indirectly, acyl-HSL production. In addition,
tslI
was found to positively regulate extracellular polysaccharide production.
Conformation of the AcrB Multidrug Efflux Pump in Mutants of the Putative Proton Relay Pathway
Authors: Su Chih-Chia , Li Ming , Gu Ruoyu , Takatsuka Yumiko , McDermott Gerry , Nikaido Hiroshi , Yu Edward W.
Published: October 2006

We previously reported the X-ray structures of wild-typeEscherichia coliAcrB, a proton motive force-dependent multidrug efflux pump, and its N109A mutant. These structures presumably reflect the resting state of AcrB, which can bind drugs. After ligand binding, a proton may bind to an acidic residue(s) in the transmembrane domain, i.e., Asp407 or Asp408, within the putative network of electrostatically interacting residues, which also include Lys940 and Thr978, and this may initiate a series of conformational changes that result in drug expulsion. Herein we report the X-ray structures of four AcrB mutants, the D407A, D408A, K940A, and T978A mutants, in which the structure of this tight electrostatic network is expected to become disrupted. These mutant proteins revealed remarkably similar conformations, which show striking differences from the previously known conformations of the wild-type protein. For example, the loop containing Phe386 and Phe388, which play a major role in the initial binding of substrates in the central cavity, becomes prominently extended into the center of the cavity, such that binding of large substrate molecules may become difficult. We believe that this new conformation may mimic, at least partially, one of the transient conformations of the transporter during the transport cycle.
Bactericidal Activity of both Secreted and Nonsecreted Microcin E492 Requires the Mannose Permease
Authors: Bieler Sylvain , Silva Filo , Soto Claudio , Belin Dominique
Published: October 2006

Microcin E492 (MccE492) is a bactericidal protein secreted byKlebsiella pneumoniaethat is active against various species ofEnterobacteriaceae. Interaction of MccE492 with target cells leads to the depolarization and permeabilization of their inner membranes. Several MccE492-specific proteins are required for the maturation and secretion of active MccE492. Surprisingly, the expression of only MceA, the polypeptide backbone of MccE492, is shown here to be toxic by itself. We refer to this phenomenon as endogenous MceA bactericidal activity to differentiate it from the action of extracellularly secreted MccE492. The toxicity of endogenous MceA is enhanced by an efficient targeting to the inner membrane. However, a periplasmic intermediate state is not required for MceA toxicity. Indeed, endogenous MceA remains fully active when it is fused to thioredoxin-1, a fast-folding protein that promotes retention of the C terminus of MceA in the cytoplasm. The C-terminal domain of MccE492 is required only for delivery from the extracellular environment to the periplasm, and it is not required for inner membrane damage. A common component is absolutely essential for the bactericidal activity of both endogenous MceA and extracellular MccE492. Indeed, toxicity is strictly dependent on the presence of ManYZ, an inner membrane protein complex involved in mannose uptake. Based on these findings, we propose a new model for cell entry, inner membrane insertion, and toxic activity of MccE492.
Survival and Growth in the Presence of Elevated Copper: Transcriptional Profiling of Copper-Stressed
Pseudomonas aeruginosa
Authors: Teitzel Gail M. , Geddie Ashley , De Long Susan K. , Kirisits Mary Jo , Whiteley Marvin , Parsek Matthew R.
Published: October 2006

Transcriptional profiles of
Pseudomonas aeruginosa
exposed to two separate copper stress conditions were determined. Actively growing bacteria subjected to a pulse of elevated copper for a short period of time was defined as a “copper-shocked” culture. Conversely, copper-adapted populations were defined as cells actively growing in the presence of elevated copper. Expression of 405 genes changed in the copper-shocked culture, compared to 331 genes for the copper-adapted cultures. Not surprisingly, there were genes identified in common to both conditions. For example, both stress conditions resulted in up-regulation of genes encoding several active transport functions. However, there were some interesting differences between the two types of stress. Only copper-adapted cells significantly altered expression of passive transport functions, down-regulating expression of several porins belonging to the OprD family. Copper shock produced expression profiles suggestive of an oxidative stress response, probably due to the participation of copper in Fenton-like chemistry. Copper-adapted populations did not show such a response. Transcriptional profiles also indicated that iron acquisition is fine-tuned in the presence of copper. Several genes induced under iron-limiting conditions, such as the siderophore pyoverdine, were up-regulated in copper-adapted populations. Interesting exceptions were the genes involved in the production of the siderophore pyochelin, which were down-regulated. Analysis of the copper sensitivity of select mutant strains confirmed the array data. These studies suggest that two resistance nodulation division efflux systems, a P-type ATPase, and a two-component regulator were particularly important for copper tolerance in
P. aeruginosa
.
A Conserved Inverted Repeat, the LipR Box, Mediates Transcriptional Activation of the
Streptomyces exfoliatus
Lipase Gene by LipR, a Member of the STAND Class of P-Loop Nucleoside Triphosphatases
Authors: Evangelista-Martínez Zahaed , González-Cerón Gabriela , Servín-González Luis
Published: October 2006

Expression of the
Streptomyces exfoliatus lipA
gene, which encodes an extracellular lipase, depends on LipR, a transcriptional activator that belongs to the STAND class of P-loop nucleoside triphosphatases. LipR is closely related to activators present in some antibiotic biosynthesis clusters of actinomycetes, forming the LipR/TchG family of regulators. In this work we showed that purified LipR protein is essential for activation of
lipA
transcription in vitro and that this transcription depends on the presence of a conserved inverted repeat, the LipR box, located upstream of the
lipA
promoter. Mutagenesis of the
lipA
promoter region indicated that most transcription depends on LipR binding to the proximal half-site of the LipR box in close proximity to the −35 region of the promoter. Our experiments also indicated that LipR establishes contact with the RNA polymerase on both sides of the LipR box, since some activation was observed when only the distal half-site was present or when the entire LipR box was moved further upstream. We also showed that the LipR proteins of
S. exfoliatus
and
Streptomyces coelicolor
are functionally interchangeable both in vitro and in vivo, revealing the functional conservation of the regulatory elements in these two species.
Heterologous Expression, Purification, and Characterization of an
l
-Ornithine
N
5
-Hydroxylase Involved in Pyoverdine Siderophore Biosynthesis in
Pseudomonas aeruginosa
Authors: Ge Li , Seah Stephen Y. K.
Published: October 2006

Pseudomonas aeruginosa
is an opportunistic pathogen that produces the siderophore pyoverdine, which enables it to acquire the essential nutrient iron from its host. Formation of the iron-chelating hydroxamate functional group in pyoverdine requires the enzyme PvdA, a flavin-dependent monooxygenase that catalyzes the
N
5
hydroxylation of
l
-ornithine.
pvdA
from
P. aeruginosa
was successfully overexpressed in
Escherichia coli
, and the enzyme was purified for the first time. The enzyme possessed its maximum activity at pH 8.0. In the absence of
l
-ornithine, PvdA has an NADPH oxidase activity of 0.24 ± 0.02 μmol min
−1
mg
−1
. The substrate
l
-ornithine stimulated this activity by a factor of 5, and the reaction was tightly coupled to the formation of hydroxylamine. The enzyme is specific for NADPH and flavin adenine dinucleotide (FAD
+
) as cofactors, as it cannot utilize NADH and flavin mononucleotide. By fluorescence titration, the dissociation constants for NADPH and FAD
+
were determined to be 105.6 ± 6.0 μM and 9.9 ± 0.3 μM, respectively. Steady-state kinetic analysis showed that the
l
-ornithine-dependent NADPH oxidation obeyed Michaelis-Menten kinetics with apparent

K
m

and
V
max
values of 0.58 mM and 1.34 μmol min
−1
mg
−1
.
l
-Lysine was a nonsubstrate effector that stimulated NADPH oxidation, but uncoupling occurred and hydrogen peroxide instead of hydroxylated
l
-lysine was produced.
l
-2,4-Diaminobutyrate,
l
-homoserine, and 5-aminopentanoic acid were not substrates or effectors, but they were competitive inhibitors of the
l
-ornithine-dependent NADPH oxidation reaction, with

K
ic

s of 3 to 8 mM. The results indicate that the chemical nature of effectors is important for simulation of the NADPH oxidation rate in PvdA.
Positive Selection on Transposase Genes of Insertion Sequences in the
Crocosphaera watsonii
Genome
Authors: Mes Ted H. M. , Doeleman Marije
Published: October 2006

Insertion sequences (ISs) are mobile elements that are commonly found in bacterial genomes. Here, the structural and functional diversity of these mobile elements in the genome of the cyanobacterium
Crocosphaera watsonii
WH8501 is analyzed. The number, distribution, and diversity of nucleotide and amino acid stretches with similarity to the transposase gene of this IS family suggested that this genome harbors many functional as well as truncated IS fragments. The selection pressure acting on full-length transposase open reading frames of these ISs suggested (i) the occurrence of positive selection and (ii) the presence of one or more positively selected codons. These results were obtained using three data sets of transposase genes from the same IS family that were collected based on the level of amino acid similarity, the presence of an inverted repeat, and the number of sequences in the data sets. Neither recombination nor ribosomal frameshifting, which may interfere with the selection analyses, appeared to be important forces in the transposase gene family. Some positively selected codons were located in a conserved domain, suggesting that these residues are functionally important. The finding that this type of selection acts on IS-carried genes is intriguing, because although ISs have been associated with the adaptation of the bacterial host to new environments, this has typically been attributed to transposition or transformation, thus involving different genomic locations. Intragenic adaptation of IS-carried genes identified here may constitute a novel mechanism associated with bacterial diversification and adaptation.
SHALLOW DONOR IMPURITY BINDING ENERGY IN A QUANTUM WIRE WITHIN AN ELECTRIC FIELD
Authors: ZHANG CHAO-JIN , GUO KANG-XIAN , XIE HONG-JING , WANG RUI-QIANG
Published: October 2006

The method of two variational wavefunctions has been used to calculate theoretically the impurity binding energy in a GaAs/Ga 1-x Al x As quantum wire. The effective potential in the quantum wire consists of a parabolic well potential in the x-direction and a square well potential in the z-direction with an applied electric field. We can obtain the results which are in good agreement with previous theoretical results. Furthermore, the impurity binding energy in the quantum wire is sensitive to the geometrical effects and the applied electric field strength F.
LASER COOLING AND TRAPPING OF ATOMIC STRONTIUM FOR ULTRACOLD ATOMS PHYSICS, HIGH-PRECISION SPECTROSCOPY AND QUANTUM SENSORS
Authors: SORRENTINO F. , FERRARI G. , POLI N. , DRULLINGER R. , TINO G. M.
Published: October 2006

This review describes the production of atomic strontium samples at ultra-low temperature and at high phase-space density, and their possible use for physical studies and applications. We describe the process of loading a magneto-optical trap from an atomic beam and preparing the sample for high precision measurements. Particular emphasis is given to the applications of ultracold Sr samples, spanning from optical frequency metrology to force sensing at micrometer scale.
THE SL2(ℂ) CASSON INVARIANT FOR SEIFERT FIBERED HOMOLOGY SPHERES AND SURGERIES ON TWIST KNOTS
Authors: BODEN HANS U. , CURTIS CYNTHIA L.
Published: October 2006

We derive a simple closed formula for the SL2(ℂ) Casson invariant for Seifert fibered homology 3-spheres using the correspondence between SL2(ℂ) character varieties and moduli spaces of parabolic Higgs bundles of rank two. These results are then used to deduce the invariant for Dehn surgeries on twist knots by combining computations of the Culler-Shalen norms with the surgery formula for the SL2(ℂ) Casson invariant.
INCOMPRESSIBLE SURFACES AND (1, 1)-KNOTS
Authors: EUDAVE-MUÑOZ MARIO
Published: October 2006

Let M be S3, S1× S2, or a lens space L(p, q), and let k be a (1, 1)-knot in M. We show that if there is a closed meridionally incompressible surface in the complement of k, then the surface and the knot can be put in a special position, namely, the surface is the boundary of a regular neighborhood of a toroidal graph, and the knot is level with respect to that graph. As an application we show that for any such M there exist tunnel number one knots which are not (1, 1)-knots.
A REAL OPTIONS APPROACH FOR PRICING ELECTRICITY TOLLING AGREEMENTS
Authors: DENG SHI-JIE , XIA ZHENDONG
Published: October 2006

An electricity tolling agreement (or, tolling contact) is a supply contract in which the buyer reserves the right to take the output of an underlying electricity generation asset by paying a predetermined premium to the asset owner. We propose a real options approach to value a tolling contract incorporating operational characteristics of the generation asset and contractual constraints. Dynamic programming and value function approximation by Monte Carlo based least-squares regression are employed to solve the valuation problem. The effects of different electricity price assumptions on the valuation of tolling contracts are examined through numerical examples.
CURRENCY CRISIS FORECASTING WITH GENERAL REGRESSION NEURAL NETWORKS
Authors: YU LEAN , LAI KIN KEUNG , WANG SHOU-YANG
Published: October 2006

The main purpose of this study is to devise a general regression neural network (GRNN)-based currency crisis forecasting model for Southeast Asian economies based upon the disastrous 1997–1998 currency crisis experience. For this some typical indicators of currency exchange rates volatility are first chosen, then these indicators are input into GRNN for training, and finally the trained GRNN is used for future crisis prediction. To verify the effectiveness of the proposed currency crisis forecasting approach, four typical Southeast Asian currencies, Indonesian rupiah, Philippine peso, Singapore dollar and Thai baht, are selected. Meantime we compare its performance with those of other forecasting methods to evaluate the forecasting ability of the proposed approach. Empirical results obtained reveal that the proposed currency crisis forecasting model has a surprisingly high degree of accuracy in judging the currency crisis level of each country in specified time period, implying that our proposed approach can be used as a feasible currency crisis early-warning system to predict currency crisis level for other countries around the world.
BSV INVESTORS VERSUS RATIONAL INVESTORS: AN AGENT-BASED COMPUTATIONAL FINANCE MODEL
Authors: ZHANG WEI , ZHANG YONGJIE , XIONG XIONG , JIN XI
Published: October 2006

BSV (Barberis, Shleifer and Vishny [Journal of Financial Economics49 (1998) 307–343]) model is one of the three major behavioral finance models. The existing BSV model is about how behavioral investors form beliefs, and is able to produce both overreaction and mean-reversion for a wide range of parameter values. However, the assumption that all investors in the market must all be BSV investors is a little strict and remains controversial. In this paper, we present an agent-based computational model of the dynamic game between BSV investors and rational investors. Time series from the artificial stock market are analyzed and two interesting findings are reported. First, the introduction of rational investors will not eliminate the anomalies of overreaction and mean-reversion. Second, no evidence is found that the BSV investors will lose money to their counterparts although their cognitive bias makes them form a false kind of expectation. On the contrary, some weak evidence is reported that BSV investors are less likely to bankrupt.
LONG-TERM MEMORY IN EMERGING MARKETS: EVIDENCE FROM THE CHINESE STOCK MARKET
Authors: MA CHAOQUN , LI HONGQUAN , ZOU LIN , WU ZHIJIAN
Published: October 2006

The notion of long-term memory has received considerable attention in empirical finance. This paper makes two main contributions. First one is, the paper provides evidence of long-term memory dynamics in the equity market of China. An analysis of market patterns in the Chinese market (a typical emerging market) instead of US market (a developed market) will be meaningful because little research on the behaviors of emerging markets has been carried out previously. Second one is, we present a comprehensive research on the long-term memory characteristics in the Chinese stock market returns as well as volatilities. While many empirical results have been obtained on the detection of long-term memory in returns series, very few investigations are focused on the market volatility, though the long-term dependence in volatility may lead to some types of volatility persistence as observed in financial markets and affect volatility forecasts and derivative pricing formulas. By means of using modified rescaled range analysis and Autoregressive Fractally Integrated Moving Average model testing, this study examines the long-term dependence in Chinese stock market returns and volatility. The results show that although the returns themselves contain little serial correlation, the variability of returns has significant long-term dependence. It would be beneficial to encompass long-term memory structure to assess the behavior of stock prices and to research on financial market theory.
TWO BI-OBJECTIVE OPTIMIZATION MODELS FOR COMPETITIVE LOCATION PROBLEMS
Authors: YANG FENGMEI , HUA GUOWEI , INOUE HIROSHI , SHI JIANMING
Published: October 2006

This paper deals with two bi-objective models arising from competitive location problems. The first model simultaneously intends to maximize market share and to minimize cost. The second one aims to maximize both profit and the profit margin. We study some of the related properties of the models, examine relations between the models and a single objective parametric integer programming problem, and then show how both bi-objective location problems can be solved through the use of a single objective parametric integer program. Based on this, we propose two methods of obtaining a set of efficient solutions to the problems of fundamental approach. Finally, a numerical example is presented to illustrate the solution techniques.
A STOCHASTIC APPROACH TO HOTEL REVENUE MANAGEMENT CONSIDERING MULTIPLE-DAY STAYS
Authors: LIU SHUQIN , LAI KIN KEUNG , DONG JICHANG , WANG SHOU-YANG
Published: October 2006

We present a stochastic optimization model for hotel revenue management with multiple-day stays under an uncertain environment. Since a decision maker may face several scenarios when renting out rooms, we use a semi-absolute deviation model to measure the risk of hotel revenue, and only consider the risk of falling below the expected revenue. The method proposed in this paper can be changed to a linear programming model by applying linearization techniques. Some examples are presented to illustrate the efficiency of this method.
Endoplasmic Reticulum Stress Signaling in Disease
Authors: Marciniak Stefan J. , Ron David
Published: October 2006

The extracellular space is an environment hostile to unmodified polypeptides. For this reason, many eukaryotic proteins destined for exposure to this environment through secretion or display at the cell surface require maturation steps within a specialized organelle, the endoplasmic reticulum (ER). A complex homeostatic mechanism, known as the unfolded protein response (UPR), has evolved to link the load of newly synthesized proteins with the capacity of the ER to mature them. It has become apparent that dysfunction of the UPR plays an important role in some human diseases, especially those involving tissues dedicated to extracellular protein synthesis. Diabetes mellitus is an example of such a disease, since the demands for constantly varying levels of insulin synthesis make pancreatic β-cells dependent on efficient UPR signaling. Furthermore, recent discoveries in this field indicate that the importance of the UPR in diabetes is not restricted to the β-cell but is also involved in peripheral insulin resistance. This review addresses aspects of the UPR currently understood to be involved in human disease, including their role in diabetes mellitus, atherosclerosis, and neoplasia.
The “Special Effect” of Case Mixing on Word Identification: Neuropsychological and Transcranial Magnetic Stimulation Studies Dissociating Case Mixing from Contrast Reduction
Authors: Braet Wouter , Humphreys Glyn
Published: October 2006

We present neuropsychological and transcranial magnetic stimulation (TMS) evidence with normal readers, that the effects of case mixing and contrast reduction on word identification are qualitatively different. Lesions and TMS applied to the right parietal lobe selectively disrupted the identification of mixed relative to single-case stimuli. Bilateral lesions and TMS applied to the occipital cortex selectively disrupted the identification of low-contrast words. These data suggest that different visual distortions (case mixing, contrast reduction) exert different effects on reading, modulated by contrasting brain regions. Case mixing is a “special” distortion and involves the recruitment of processes that are functionally distinct, and dependent on different regions in the brain, from those required to deal with contrast reduction.
Auditory Language Comprehension in Children with Developmental Dyslexia: Evidence from Event-related Brain Potentials
Authors: Sabisch B. , Hahne A. , Glass E. , von Suchodoletz W. , Friederici A. D.
Published: October 2006

In the present study, event-related brain potentials (ERPs) were used to compare auditory sentence comprehension in 16 children with developmental dyslexia (age 9–12 years) and unimpaired controls matched on age, sex, and nonverbal intelligence. Passive sentences were presented, which were either correct or contained a syntactic violation (phrase structure) or a semantic violation (selectional restriction). In an overall sentence correctness judgment task, both control and dyslexic children performed well. In the ERPs, control children and dyslexic children demonstrated a similar N400 component for the semantic violation. For the syntactic violation, control children demonstrated a combined pattern, consisting of an early starting bilaterally distributed anterior negativity and a late centro-parietal positivity (P600). Dyslexic children showed a different pattern that is characterized by a delayed left lateralized anterior negativity, followed by a P600. These data indicate that dyslexic children do not differ from unimpaired controls with respect to semantic integration processes (N400) or controlled processes of syntactic reanalyses (P600) during auditory sentence comprehension. However, early and presumably highly automatic processes of phrase structure building reflected in the anterior negativity are delayed in dyslexic children. Moreover, the differences in hemispheric distribution of the syntactic negativity indicate different underlying processes in dyslexic children and controls. The bilateral distribution in controls suggests an involvement of right hemispherically established prosodic processes in addition to the left hemispherically localized syntactic processes, supporting the view that prosodic information may be used to facilitate syntactic processing during normal comprehension. The left hemispheric distribution observed for dyslexic children, in contrast, suggests that these children do not rely on information about the prosodic contour during auditory sentence comprehension as much as controls do. This finding points toward a phonological impairment in dyslexic children that might hamper the development of syntactic processes.
Repetitive Transcranial Magnetic Stimulation Dissociates Working Memory Manipulation from Retention Functions in the Prefrontal, but not Posterior Parietal, Cortex
Authors: Postle Bradley R. , Ferrarelli Fabio , Hamidi Massihullah , Feredoes Eva , Massimini Marcello , Peterson Michael , Alexander Andrew , Tononi Giulio
Published: October 2006

Understanding the contributions of the prefrontal cortex (PFC) to working memory is central to understanding the neural bases of high-level cognition. One question that remains controversial is whether the same areas of the dorsolateral PFC (dlPFC) that participate in the manipulation of information in working memory also contribute to its short-term retention (STR). We evaluated this question by first identifying, with functional magnetic resonance imaging (fMRI), brain areas involved in manipulation. Next, these areas were targeted with repetitive transcranial magnetic stimulation (rTMS) while subjects performed tasks requiring only the STR or the STR plus manipulation of information in working memory. fMRI indicated that manipulation-related activity was independent of retention-related activity in both the PFC and superior parietal lobule (SPL). rTMS, however, yielded a different pattern of results. Although rTMS of the dlPFC selectively disrupted manipulation, rTMS of the SPL disrupted manipulation and STR to the same extent. rTMS of the postcentral gyrus (a control region) had no effect on performance. The implications of these results are twofold. In the PFC, they are consistent with the view that this region contributes more importantly to the control of information in working memory than to its STR. In the SPL, they illustrate the importance of supplementing the fundamentally correlational data from neuroimaging with a disruptive method, which affords stronger inference about structure-function relations.
Transverse Patterning and Human Amnesia
Authors: Rickard Timothy C. , Verfaellie Mieke , Grafman Jordan
Published: October 2006

The transverse patterning (TP) task (A+ B−, B+ C−, C+ A−) has played a central role in testing the hypothesis that medial-temporal (and, in particular, hippocampal) brain damage selectively impairs learning on at least some classes of configural (i.e., nonlinear) learning tasks. Results in the animal and human literature generally support that hypothesis. Reed and Squire [Impaired transverse patterning in human amnesia is a special case of impaired memory for two-choice discrimination tasks. Behavioral Neuroscience, 113, 3–9, 1999], however, advanced an alternative account in which impaired TP performance in amnesia reflects a generic scaling artifact arising from the greater difficulty of the TP task compared to the elemental (i.e., linear) control task that is typically used. We begin with a critique of Reed and Squire, countering their conceptual arguments and showing that their results, when analyzed appropriately, support the configural deficit hypothesis. We then report results from eight new amnesic patients and controls on an improved version of the TP task. Despite substantial practice, accuracy of patients with bilateral hippocampal damage due to anoxia reached and maintained an asymptote of only 54% correct, well below the maximum accuracy obtainable (67%) in the absence of configural learning. A patient with selective bilateral damage to the anterior thalamic nuclei exhibited a TP accuracy asymptote that was near 67%, a pattern of two out of three correct consecutive trials, and a pattern of nearly always answering correctly for two of the three TP item pairs. These results are consistent with a set of unique and parameter-free predictions of the configural deficit hypothesis.
Formal Leadership in Multilateral Negotiations: A Rational Institutionalist Theory
Authors: Tallberg Jonas
Published: October 2006

The exercise of leadership by the chairs of multilateral negotiations has so far received limited systematic attention in scholarship on international cooperation. This article addresses this gap by presenting a rational institutionalist theory of formal leadership that provides answers to three central questions: Why do states delegate powers of process control to the chairmanship of international negotiations? What are the power resources of formal leaders? And when, why and how do negotiation chairs wield influence over the outcomes of multilateral bargaining? The theory suggests that chairmanships are empowered to fulfil functions of agenda management, brokerage, and representation in international bargaining; identifies procedural control and privileged information as essential power resources of negotiation chairs; and isolates the conditions under which formal leaders shape the efficiency and distributional implications of multilateral bargaining. The article ends by outlining an alternative theoretical approach to formal leadership, drawn from sociological institutionalism.
The Presidency: The Role(s) of the Chair in European Union Negotiations
Authors: Elgström Ole
Published: October 2006

Using role theory as its analytical basis, this article delineates and analyses the specific characteristics of the Chair in the European Union (EU). The focus is thus on the EU Council Presidency and on how expectations surrounding the office impact upon its performance as administrator, agenda manager, broker, leader and representative. The EU's institutional design is marked by a rotating Presidency, by relatively short Presidency periods and by a mix of unanimity and majority voting. These traits influence the ways in which the Chair performs its role. The major argument is, however, that existing structurally based expectations of the Presidency's role (that is, expectations of neutrality and impartiality, of effectiveness and of consensus-seeking) interact with the particular role conceptions that are brought to the office by individual member states to produce both common features and variety in role performance. Empirical illustrations are taken from recent EU Presidencies to highlight continuity and fluctuation in Presidency performances.
Parameters of the Chairmanship's Effectiveness: The Case of the UN Security Council
Authors: Blavoukos Spyros , Tsakonas Panayotis , Bourantonis Dimitris
Published: October 2006

The article discusses the parameters conditioning the chair's effectiveness in international multilateral negotiations. Building on existing accounts of Presidential functions, an analytical typology of these parameters is provided, elaborating on the direction and magnitude of their impact. Conditioning parameters are clustered into three categories: the broader international environment in which the chair operates and the issues with which (s)he is called to deal; organization-specific features of an institutional and political nature; and the chair's personal skills and country-of-origin attributes. The potential for effect of these parameters is illustrated by reference to the chairmanship of the UN Security Council (SC). The origins, institutional features and main tasks of the Council are discussed, as well as the role of its chair as an agenda manager and broker. It is argued that the SC President's role well exceeds the formal tasks that are stipulated in the Rules of Procedure. Although mainly procedural in nature, these tasks may have important political implications, stressing the informal component of Presidential intervention. The conditioning parameters identified have a catalytic impact upon and account for the great variance in SC chair performance and the effectiveness of the chair's intervention.
Diagnosis of Variability and Trends in a Global Precipitation Dataset Using a Physically Motivated Statistical Model
Authors: Sapiano M. R. P. , Stephenson D. B. , Grubb H. J. , Arkin P. A.
Published: October 2006

A physically motivated statistical model is used to diagnose variability and trends in wintertime (October–March) Global Precipitation Climatology Project (GPCP) pentad (5-day mean) precipitation. Quasigeostrophic theory suggests that extratropical precipitation amounts should depend multiplicatively on the pressure gradient, saturation specific humidity, and the meridional temperature gradient. This physical insight has been used to guide the development of a suitable statistical model for precipitation using a mixture of generalized linear models: a logistic model for the binary occurrence of precipitation and a Gamma distribution model for the wet day precipitation amount.

The statistical model allows for the investigation of the role of each factor in determining variations and long-term trends. Saturation specific humidity qs has a generally negative effect on global precipitation occurrence and with the tropical wet pentad precipitation amount, but has a positive relationship with the pentad precipitation amount at mid- and high latitudes. The North Atlantic Oscillation, a proxy for the meridional temperature gradient, is also found to have a statistically significant positive effect on precipitation over much of the Atlantic region. Residual time trends in wet pentad precipitation are extremely sensitive to the choice of the wet pentad threshold because of increasing trends in low-amplitude precipitation pentads; too low a choice of threshold can lead to a spurious decreasing trend in wet pentad precipitation amounts. However, for not too small thresholds, it is found that the meridional temperature gradient is an important factor for explaining part of the long-term trend in Atlantic precipitation.