bluuebunny/crossref_metadata_2025 huggingface dataset:
Common interchange standards for proteomics data: Public availability of tools and schema. Report on the Proteomic Standards Initiative Workshop, 2nd Annual HUPO Congress, Montreal, Canada, 8–11th October 2003
Authors: Orchard Sandra , Hermjakob Henning , Julian Randall K. , Runte Kai , Sherman David , Wojcik Jérôme , Zhu Weimin , Apweiler Rolf
Published: January 2004

The Proteomics Standards Initiative (PSI) aims to define community standards for data representation in proteomics and to facilitate data comparision, exchange and verification. To this end, a Level 1 Molecular Interaction XML data exchange format has been developed which has been accepted for publication and is freely available at the PSI website (http.//psidev.sf.net/). Several major protein interaction databases are already making data available in this format. A draft XML interchange format for mass spectrometry data has been written and is currently undergoing evaluation whilst work is ongoing to develop a proteomics data integration model, MIAPE.
Model predictive control of linear systems with nonlinear terminal control
Authors: Chen Wen‐Hua , Hu Xiao‐Bing
Published: January 2004

In terminal weighting based model predictive control (MPC) algorithms, the terminal weighting term is used to cover the performance cost under the terminal control for guaranteeing stability. Therefore, the terminal control is crucial in choosing the terminal weighting term and also determining/estimating the stability region. However, most of the existing MPC algorithms are developed based on linear terminal control which restricts the achievable performance and stability of MPC. For linear systems, an MPC algorithm with nonlinear terminal control is presented in this paper, where the gain of the terminal control varies with the terminal state. An offline algorithm is proposed to determine the nonlinear gains and to choose the associated terminal weighting term. It is shown that, compared with the MPC algorithms with fixed linear terminal gain, a nonlinear terminal control results in a much larger stability region, which is confirmed by a numerical example. Copyright © 2004 John Wiley & Sons, Ltd.
Asymmetric constraints with polytopic sets in MPC with application to coupled tanks system
Authors: Kouvaritakis B. , Cannon M. , Karas A. , Rohal‐Ilkiv B. , Belavy C.
Published: January 2004

Asymmetric constraints have not received sufficient attention in the MPC literature, possibly due to the popularity of ellipsoidal terminal regions, which for asymmetric constraints would give conservative results. The work here adopts low‐complexity polyhedra for which invariance and feasibility under asymmetric constraints can be handled through the use of Farkas' lemma and related results. The paper embeds these results into an MPC law based on a dual mode prediction strategy and proposes algorithms for the systematic design of the polytopic terminal sets. The efficacy of the results is illustrated through application to a coupled tanks system. Copyright © 2004 John Wiley & Sons, Ltd.
Finite constraint set receding horizon quadratic control
Authors: Quevedo Daniel E. , Goodwin Graham C. , De Doná José A.
Published: January 2004

This contribution addresses the problem of discrete time receding horizon quadratic control for plants whose input is restricted to belong to a finite set. We also study the dynamics of the resulting closed‐loop system. Based upon the geometry of the underlying quadratic programme, a finitely parametrized expression for the control law is derived, which makes use of vector quantizers. Alternatively, the control law can be formulated by means of a polyhedral partition of the state space, which is closely connected with the partition induced when considering saturation‐like constraints. Exact analytic expressions for the partition can be developed, therefore avoiding the need for on‐line optimization. The closed‐loop system, comprising controller and plant, exhibits highly nonlinear dynamics, due to the finite set restriction. Asymptotic stability only holds for very special cases. In general, this notion is too strong. Nevertheless, ultimate boundedness of state trajectories is often achieved. Tools for determining positively invariant sets, hence ensuring ultimate boundedness, are presented. Copyright © 2004 John Wiley & Sons, Ltd.
Predictive control of thermal Power Plants
Authors: Aurora C. , Magni L. , Scattolini R. , Colombo P. , Pretolani F. , Villa G.
Published: January 2004

This work presents the results of a project aimed at verifying the applicability of industrial model predictive control (MPC) to thermal Power Plants. The research is motivated by the need to improve the efficiency of power plants so as to cope with the high levels of competition induced by the deregulation of the energy market. A detailed plant simulator, already used for operators training and controllers tuning, is coupled to an industrial software package implementing the dynamic matrix control algorithm. The achieved results witness the great potentialities of MPC, with respect to classical decentralized schemes, in terms of economical savings, reduction of pollutants, improved flexibility, easier tuning and better documentation. Copyright © 2004 John Wiley & Sons, Ltd.
African American women in higher education
Authors: Zamani Eboni M.
Published: January 2004

This chapter provides an overview of the historical roles and contemporary educational challenges and opportunities for African American women.
Theoretical frameworks for African American women
Authors: Howard‐Hamilton Mary F.
Published: January 2004

Applying appropriate theoretical frameworks for black women is challenging because many theories are very general and do not consider multiple identities and roles. Critical race theory and black feminist thought are suggested as appropriate frameworks and applied to the needs of black women in higher education.
Come to the river: Using spirituality to cope, resist, and develop identity
Authors: Watt Sherry K.
Published: January 2004

This chapter describes and discusses spiritual lives of African American female college students, including elements of coping, resisting, and developing identity.
Personal, academic, and career counseling of African American women in college settings
Authors: Constantine Madonna G. , Greer Tawanda M.
Published: January 2004

This chapter provides information about personal, academic, and vocational concerns of African American college women and offers culturally relevant counseling frameworks and interventions for working with this population.
Programming needs and student services for African American women
Authors: Rosales Alexandria M. , Person Dawn R.
Published: January 2004

An overview and context of holistic practices for serving African American women is presented. The needs, expectations, and aspirations of this population are addressed. Examples of and recommendations for programs and services are provided.
The experiences of African American women faculty and administrators in higher education: Has anything changed?
Authors: Patitu Carol Logan , Hinton Kandace G.
Published: January 2004

This chapter explores factors of concern for, and overall experiences of, African American female faculty and administrators, including salary issues, affirmative action, racism, sexism, homophobia, campus climate, isolation, tenure and promotion processes, and salary.
Insights: emphasizing issues that affect African American women
Authors: Hughes Robin L. , Howard‐Hamilton Mary F.
Published: January 2004

This chapter continues and expands the dialogue regarding the oppressions experienced by African American women in higher education. Stakeholders of postsecondary education are invited to use this dialogue to become more aware of the needs of African American women on college campuses, as well as African American people in general.
Unique sugar metabolism and novel enzymes of hyperthermophilic archaea
Authors: Sakuraba Haruhiko , Goda Shuichiro , Ohshima Toshihisa
Published: January 2004

Hyperthermophiles are a group of microorganisms that have their optimum growth temperature above 80°C. More than 60 species of the hyperthermophiles have been isolated from marine and continental volcanic environments. Most hyperthermophiles belong to Archaea, the third domain of life, and are considered to be the most ancient of all extant life forms. Recent studies have revealed the presence of unusual sugar metabolic processes in hyperthermophilic archaea, for example, a modified Embden‐Meyerhof pathway, that has so far not been observed in bacteria and eucarya. Several novel enzymes, such as ADP‐dependent glucokinase, ADP‐dependent phosphofructokinase, glyceraldehyde‐3‐phosphate ferredoxin oxidoreductase, phosphoenolpyruvate synthase, pyruvate : ferredoxin oxidoreductase, and ADP‐forming acetyl‐CoA synthetase, have been found to be involved in a modified Embden‐Meyerhof pathway of the hyperthermophilic archaeon Pyrococcus furiosus. In addition, a unique mode of ATP regeneration has been postulated to exist in the pathway of P. furiosus. The metabolic design observed in this microorganism might reflect the situation at an early stage of evolution. © 2004 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 3: 281–287; 2004: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.10066
Metal‐catalyzed reactions of diborons for synthesis of organoboron compounds
Authors: Ishiyama Tatsuo , Miyaura Norio
Published: January 2004

Metal‐catalyzed borylation of alkenes, alkynes, arenes, and organic halides with B–B or H–B compounds has been developed for the synthesis of organoboron compounds from simple organic substrates. The platinum(0)‐catalyzed addition of bis(pinacolato)diboron to alkenes and alkynes provided a method for the stereoselective synthesis of cis‐bis(boryl)alkanes or cis‐bis(boryl)alkenes. The addition of diboron to 1,3‐dienes with platinum(0) complexes provided a new access to cis‐1,4‐bis(boryl)‐2‐butene derivatives, which are versatile reagents for diastereoselective allylboration of carbonyl compounds. The first one‐step procedure for the syntheses of aryl‐, vinyl‐, and allylboronates was achieved via crosscoupling reactions of diborons with aryl and 1‐alkenyl halides or triflates and allyl acetates. Direct CH borylation of arenes catalyzed by a transition metal complex was studied as an economical protocol for the synthesis of a variety of arylboron derivatives. Ir‐catalyzed CH borylation of arenes, heteroarenes, and benzylic positions of alkylarenes by bis(pinacolato)diboron or pinacolborane furnished aryl‐, heteroaryl‐, and benzylboron compounds. This article discusses the mechanisms of these reactions and their synthetic applications. © 2004 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 3: 271–280; 2004: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.10068
Lessons learned from macrolide synthesis
Authors: Mulzer Johann , Martin Harry J.
Published: January 2004

The highlights of three macrolide syntheses recently completed in our laboratory are described. In the epothilone B synthesis we developed the “early epoxide approach,” which resulted in the first completely stereocontrolled synthesis of this natural product. In the laulimalide synthesis our contribution was the auxiliary controlled ene‐macrocyclization and Sharpless' kinetic resolution for achieving a regioselective epoxidation of two pseudo‐enantiomorphic allylic alcohol subunits. The tartrolon B synthesis was the first to be completed. In this case, a substrate controlled aldol addition was used to assemble the entire carbon skeleton of the compound. © 2004 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 3: 258–270; 2004: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.10069
Exhaled breath condensate (EBC) collection in cats—description of a non-invasive technique to investigate airway disease
Authors: Sparkes Andrew H. , Mardell Eleanor J. , Deaton Chris , Kirschvink Nathalie , Marlin David
Published: January 2004

Exhaled breath condensate has been collected in other species and used as a non-invasive method of evaluating airway disease by measurement of various markers in the fluid, including hydrogen peroxide, nitric oxide, leukotrienes and prostaglandins. We describe a novel technique for the collection of exhaled breath condensate from cats, which enabled collection of fluid and measurement of its hydrogen peroxide concentration. Further studies will be needed to establish the value of this technique in the investigation of feline respiratory disease.
Mechanical interface conditions affect morphology and cellular activity of sclerotic bone rims forming around experimental loaded implants
Authors: Vestermark Marianne Toft , Bechtold Joan E. , Swider Pascal , Søballe Kjeld
Published: January 2004

A characteristic bony structure found at revision surgery for failed joint replacement, and implicated as being associated with poorer subsequent implant fixation, is a sclerotic bone rim (SB rim). This study is a histomorphometric analysis of the SB rim formed around an experimental canine micro‐motion implant system under stable or unstable conditions with polyethylene (PE) particles, after 8 weeks. A point count histomorphometric analysis was performed to determine the cellular activity at the surface of the SB rim, and the morphology of the structure was determined by image analysis. A SB rim was found to form under both stable and unstable conditions, but with unstable conditions the rim was more distinct, thick, continuous, and was located near the drill hole, and had high and ongoing formative activity at both surfaces with little resorption. Under stable conditions, thinner second or third SB rims were observed. The difference in width and distance between implant and the SB rim is significant (p < 0.05), as was the difference in fraction of resorption surfaces at the SB surface facing the implant. This study observed an in vivo primary bone response to controlled stable and unstable loaded implants. Sclerosis of trabeculae in a semi‐continuous SB rim can serve to isolate the implant from the marrow space. The increases in SB rim width and continuity is consistent with the previously demonstrated knowledge that increase of total bone mass and low risk for trabeculae perforation is the consequence of low resorptive and high formative activity. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
Cyclic strain influences the expression of the vascular endothelial growth factor (VEGF) and the hypoxia inducible factor 1 alpha (HIF‐1α) in tendon fibroblasts
Authors: Petersen Wolf , Varoga Deike , Zantop Thore , Hassenpflug Joachim , Mentlein Rolf , Pufe Thomas
Published: January 2004

Neovascularization is involved in beneficial and detrimental processes of tendon pathology.

We investigated the influence of repetitive motion on the expression of the most important angiogenic factor, the vascular endothelial growth factor (VEGF) in the 3T3 NIH fibroblast cell line and in cultures of rat Achilles tendon fibroblasts. Monolayers of subconfluently grown cells were stretched in rectangular silicone dishes with cyclic uniaxial movement. Strain was applied over 24 h varying the frequency (0.5–1 Hz).

Fibroblasts (3T3 fibroblasts and rat Achilles tendon cultures) cultivated without the application of cyclic strain released measurable VEGF amounts into their culture supernatants. Cyclic stretching of the cells with a frequency of 1 Hz resulted in an increased expression of VEGF. A low frequency (0.5 Hz) reduced VEGF expression to control levels. RT PCR revealed VEGF 121 and VEGF 165 as the only splice forms that were induced by cyclic stretching. Western blot experiments could further show that cyclic stretching induced activation of the transcription factor HIF‐1α. These results demonstrate that mechanical factors are involved in the regulation of VEGF expression in tendon tissue. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
Dilemmas and promises of Russian liberalism
Authors: Tsygankov Pavel A. , Tsygankov Andrei P.
Published: January 2004

The authors analyze the divisions within Russian liberalism—another influential IR theory—and the contradictory nature of this intellectual movement. In particular, they draw the attention to the debate between pro-Western and more nationally oriented liberals, which they view in terms of the familiar disagreement between supporters of cosmopolitan and communitarian thoughts. Whereas cosmopolitans insist on the emergence of a single humanity and emphasize the factors of unifying and homogenizing nature, communitarians underscore the role of national and cultural foundations in building democratic institutions in the world. The authors trace how various liberal currents perceive the nature of the post-Cold War order, Russia’s national interests, and its foreign policy orientations.
Apg‐2 has a chaperone‐like activity similar to Hsp110 and is overexpressed in hepatocellular carcinomas
Authors: Gotoh Kazuhisa , Nonoguchi Kohsuke , Higashitsuji Hiroaki , Kaneko Yoshiyuki , Sakurai Toshiharu , Sumitomo Yasuhiko , Itoh Katsuhiko , Subjeck John R , Fujita Jun
Published: January 2004

Hepatocellular carcinoma (HCC) is the fifth most common cancer in the world. We constructed subtracted cDNA libraries enriched with genes overexpressed in HCCs. Among the 17 genes identified were molecular chaperones, Hsp110, Hsp90B, and Hsp70‐1. Expression of the Hsp110 family members was further analyzed, and increased transcript levels of Hsp110 and Apg‐2, but not Apg‐1, were found in 12 and 14, respectively, of 18 HCCs. Immunohistochemical analysis demonstrated the overexpression of the proteins in tumor cells. Apg‐2 had chaperone ability similar to Hsp110 in a thermal denaturation assay using luciferase, and showed anti‐apoptotic activity. These results suggest that the Hsp110 family members play important roles in hepatocarcinogenesis through their chaperoning activities.
A new modified DNA enzyme that targets influenza virus A mRNA inhibits viral infection in cultured cells
Authors: Takahashi Hitoshi , Hamazaki Hiroyuki , Habu Yuichiro , Hayashi Mieko , Abe Takayuki , Miyano-Kurosaki Naoko , Takaku Hiroshi
Published: January 2004

DNA enzymes are RNA‐cleaving single‐stranded DNA molecules. We designed DNA enzymes targeting the PB2 mRNA translation initiation (AUG) region of the influenza A virus (A/PR/8/34). The modified DNA enzymes have one or two N3′‐P5′ phosphoramidate bonds at both the 3′‐ and 5′‐termini of the oligonucleotides, which significantly enhanced their nuclease resistance. These modified DNA enzymes had the same cleavage activity as the unmodified DNA enzymes, determined by kinetic analyses, and reduced influenza A virus replication by more than 99%, determined by plaque formation. These DNA enzymes are highly specific; their protective effect was not observed in influenza B virus (B/Ibaraki)‐infected Madin–Darby canine kidney cells.
The artificial zinc finger protein ‘Blues’ binds the enhancer of the fibroblast growth factor 4 and represses transcription
Authors: Libri V , Onori A , Fanciulli M , Passananti C , Corbi N
Published: January 2004

The design of novel genes encoding artificial transcription factors represents a powerful tool in biotechnology and medicine. We have engineered a new zinc finger‐based transcription factor, named Blues, able to bind and possibly to modify the expression of fibroblast growth factor 4 (FGF‐4, K‐fgf), originally identified as an oncogene. Blues encodes a three zinc finger peptide and was constructed to target the 9 bp DNA sequence: 5′‐GTT‐TGG‐ATG‐3′, internal to the murine FGF‐4 enhancer, in proximity of Sox‐2 and Oct‐3 DNA binding sites. Our final aim is to generate a model system based on artificial zinc finger genes to study the biological role of FGF‐4 during development and tumorigenesis.
The MAP kinase kinase NtMEK2 is involved in tobacco pollen germination
Authors: Voronin Viktor , Aionesei Tatiana , Limmongkon Apinun , Barinova Ioulia , Touraev Alisher , Laurière Christiane , Coronado Marı́a-José , Testillano Pilar S , Risueño Maria-Carmen , Heberle-Bors Erwin , Wilson Cathal
Published: January 2004

The tobacco ntf4 mitogen‐activated protein (MAP) kinase gene (and its encoded protein p45Ntf4) is expressed at later stages of pollen maturation. We have found that the highly related MAP kinase SIPK is also expressed in pollen and, like p45Ntf4, is activated upon pollen hydration. The MAP kinase kinase NtMEK2 activates SIPK, and here we show that it can also activate p45Ntf4. In an attempt to inhibit the function of both MAP kinases simultaneously we constructed a loss‐of‐function mutant version of NtMEK2, which, in transient transformation assays, led to an inhibition of germination in the transformed pollen grains. These data indicate that NtMEK2, and by inference its substrates p45Ntf4 and/or SIPK, are involved in pollen germination.
CONVEXITY IN TANDEM QUEUES
Authors: Koole Ger
Published: January 2004

We derive convexity results and related properties for the value
functions of tandem queuing systems. The results for standard
multiserver queues are new. For completeness, we also prove and
generalize existing results on tandems of controllable queues. The
results can be used to compare queuing systems. This is done for
systems with and without batch arrivals and for systems with different
numbers of on–off sources.
A PERIODIC-REVIEW INVENTORY SYSTEM WITH SUPPLY INTERRUPTIONS
Authors: Li Zhaolin , Xu Susan H. , Hayya Jack
Published: January 2004

Supply interruptions resulting from unpredictable events, such as
machine breakdowns, order cancellations, unscheduled maintenance, and
labor strikes can produce adverse effects on the
production/inventory system. In this article, we consider a
periodic-review inventory system subject to random demand and
unreliable supply. The availability of supply is modeled as an
alternating renewal process with general distributions for the
durations of the UP and DOWN cycles. We consider the lost-sales case
and also discuss the backorder case, for both the discounted and
long-run average cost criteria. For the linear cost model, we derive
the structural properties and bounds of the optimal policy. We also
propose the “end-of-cycle” inventory return contract and
show that it may be mutually beneficial to both the firm and the
supplier.
RUIN PROBABILITY UNDER COMPOUND POISSON MODELS WITH RANDOM DISCOUNT
FACTOR
Authors: Ng Kai W. , Yang Hailiang , Zhang Lihong
Published: January 2004

In this article, we consider a compound Poisson insurance risk model
with a random discount factor. This model is also known as the compound
filtered Poisson model. By using some stochastic analysis techniques, a
convergence result for the discounted surplus process, an expression
for the ruin probability, and the upper bounds for the ruin probability
are obtained.
UNIFORM ESTIMATES FOR THE TAIL PROBABILITY OF MAXIMA OVER FINITE
HORIZONS WITH SUBEXPONENTIAL TAILS
Authors: Tang Qihe
Published: January 2004

Let F be the common distribution function of the increments
of a random walk {Sn, n ≥ 0}
with S0 = 0 and a negative drift and let
{N(t), t ≥ 0} be a general counting
process, independent of {Sn, n
≥ 0}. This article investigates the tail probability, denoted by
ψ(x; t), of the maximum of
SN(v) over a finite horizon 0
≤ v ≤ t. When F is strongly
subexponential, some asymptotics for ψ(x; t) are
derived as x → ∞. The merit is that all of the
obtained asymptotics are uniform for t in a finite or infinite
time interval.
LOWER BOUNDS FOR LRD/GI/1 QUEUES WITH SUBEXPONENTIAL
SERVICE TIMES
Authors: Xia Cathy H. , Liu Zhen , Squillante Mark S. , Zhang Li
Published: January 2004

We investigate the tail distribution of the virtual waiting times in
a LRD/GI/1 queue where the arrival process is
long-range dependent (LRD) and the service times are independent and
identically distributed (i.i.d.) random variables. We present two lower
bounds on the stationary waiting time tail asymptotics, which
illustrate the different dominating components that influence server
performance under various conditions. In particular, we show that the
tail distribution of the stationary waiting time is bounded below by
that of the associated LRD/D/1 queues
resulting from replacing all random service times by the mean. This
shows the performance impact purely due to the long-range dependency of
the arrival process. On the other hand, when the service times are
subexponential, we show that the tail distribution of the stationary
waiting time is bounded below by that of the corresponding
D/GI/1 queue by replacing the dependent
arrival process with its associated independent version. This shows the
minimum performance impact due to the tail distribution of the service
times. The above two lower bounds indicate that the performance of
LRD/GI/1 queues will be dominated by the
heavier tail of the corresponding LRD/D/1 and
D/GI/1 queues. These features are further
illustrated and quantified through examples and via numerous simulation
experiments.
Retinal projections in the cat: A cholera toxin B subunit study
Authors: MATTEAU ISABELLE , BOIRE DENIS , PTITO MAURICE
Published: January 2004

The B fragment of cholera toxin (CTb) is a highly sensitive
anterograde tracer for the labelling of retinal axons. It can reveal
dense retinofugal projections to well-known retinorecipient nuclei
along with sparse but distinct input to target areas that are not
commonly recognized. Following a unilateral injection of CTb into the
vitreous chamber of seven adult cats, we localized the toxin
immunohistochemically in order to identify direct retinal projections
in these animals. Consistent with previous findings, the strongest
projections were observed in the superficial layers of the superior
colliculus, the dorsal and ventral lateral geniculate nuclei, the
pretectal nuclei, the accessory optic nuclei, and the suprachiasmatic
nucleus of the hypothalamus. However, we also found labelled terminals
in several other brain areas, including the zona incerta, the medial
geniculate nucleus, the lateral posterior-pulvinar complex, the lateral
habenular nucleus, and the anterior and lateral hypothalamic regions.
The morphological characteristics of the retinal axon terminals in most
of the identified novel target sites are described.
Video-rate and continuous visual stimuli do not produce equivalent
response timings in visual cortical neurons
Authors: GAWNE TIMOTHY J. , WOODS JILL M.
Published: January 2004

Video cathode ray tube (CRT) technology has proven to be extremely
valuable for performing research in the visual system. However, the
image on a CRT monitor is not constant, but consists of a series of
brief pulses. This has implications for any study that explores the
responses of neurons in the visual system on short time scales. In
particular, there is no unambiguous time point at which a visual
stimulus presented via CRT may be said to have ended.
Recordings from single units in visual cortical area V1 of an awake
primate demonstrate that, when studying changes in response timing on
the order of 10 ms or less, stimuli delivered at video frame rates do
not duplicate the effects seen with stimuli that have continuous
functions of luminance versus time. Additionally, there does not seem
to be any clear method of comparing the results obtained with
video-rate stimuli with results obtained with continuous-time stimuli
that holds for all conditions. These effects are especially critical
when exploring the time course of the neuronal responses to the ending
of a visual stimulus (off-response). Our findings cast doubt upon the
recently reported result that off-responses have consistently shorter
latencies than on-responses.
Hyper-vision in a patient with central and paracentral vision loss reflects cortical reorganization
Authors: CASCO CLARA , CAMPANA GIANLUCA , GRIECO ALBA , MUSETTI SILVANA , PERRONE SALVATORE
Published: January 2004

SM, a 21-year-old female, presents an extensive central scotoma (30 deg) with dense absolute scotoma (visual acuity = 10/100) in the macular area (10 deg) due to Stargardt's disease. We provide behavioral evidence of cortical plastic reorganization since the patient could perform several visual tasks with her poor-vision eyes better than controls, although high spatial frequency sensitivity and visual acuity are severely impaired. Between 2.5-deg and 12-deg eccentricities, SM presented (1) normal acuity for crowded letters, provided stimulus size is above acuity thresholds for single letters; (2) a two-fold sensitivity increase (d-prime) with respect to controls in a simple search task; and (3) largely above-threshold performance in a lexical decision task carried out randomly by controls. SM's hyper-vision may reflect a long-term sensory gain specific for unimpaired low spatial-frequency mechanisms, which may result from modifications in response properties due to practice-dependent changes in excitatory/inhibitory intracortical connections.
Limulusopsins: Diurnal regulation of expression
Authors: DALAL JASBIR S. , JINKS ROBERT N. , CACCIATORE CHELSIE , GREENBERG ROBERT M. , BATTELLE BARBARA-ANNE
Published: January 2004

Much has been learned from studies ofLimulusphotoreceptors about the role of the circadian clock and light in the removal of photosensitive membrane. However, little is known in this animal about mechanisms regulating photosensitive membrane renewal, including the synthesis of proteins in, and associated with, the photosensitive membrane. To begin to understand renewal, this study examines diurnal changes in the levels of mRNAs encoding opsin, the integral membrane protein component of visual pigment, and the relative roles of light and the circadian clock in producing these changes. We show that at least two distinct opsin genes encoding very similar proteins are expressed in both the lateral and ventral eyes, and that during the day and night in the lateral eye, the average level of mRNA encoding opsin1 is consistently higher than that encoding opsin2. Northern blot assays showed further that total opsin mRNA in the lateral eyes of animals maintained under natural illumination increases during the afternoon (9 & 12 h after sunrise) in the light and falls at night in the dark. This diurnal change occurs whether or not the eyes receive input from the circadian clock, but it is eliminated in eyes maintained in the dark. Thus, it is regulated by light and darkness, not by the circadian clock, with light stimulating an increase in opsin mRNA levels. The rise in opsin mRNA levels observed under natural illumination was seasonal; it occurred during the summer but not the spring and fall. However, a significant increase in opsin mRNA levels could be achieved in the fall by exposing lateral eyes to 3 h of natural illumination followed by 9 h of artificial light. The diurnal regulation of opsin mRNA levels contrasts sharply with the circadian regulation of visual arrestin mRNA levels (Battelle et al., 2000). Thus, inLimulus, distinctly different mechanisms regulate the levels of mRNA encoding two proteins critical for the photoresponse.
Modulation of the components of the rat dark-adapted
electroretinogram by the three subtypes of GABA receptors
Authors: MÖLLER ANNA , EYSTEINSSON THOR
Published: January 2004

The separate components of the dark-adapted electroretinogram (ERG)
are believed to reflect the electric activity of neurones in both the
inner and the outer layers of the retina, although their precise origin
still remains unclear. The purpose of this study was to examine whether
selective blockage or stimulation of the different subtypes of GABA
receptors might help further elucidate the cellular origin of the
components of the dark-adapted ERG. The rat retina is of interest since
the localization and physiology of GABA receptors in that retina have
been examined in great detail. GABA agonists and antagonists, known to
affect the responses of neurons in the inner plexiform layer, were
injected into the vitreous of one eye while ERG responses evoked by
flashes of white light were recorded. GABA and the GABAa
agonist isoguvacine completely removed the oscillatory potentials (OPs)
and reduced the amplitude of the a- and b-waves.
TPMPA, a GABAc antagonist, reduced the a- and
b-waves but had no significant effect on the OPs. Baclofen, a
GABAb agonist, reduced the amplitude of the a- and
b-waves, without having any effects on the amplitude of the
OPs. The GABAb antagonist CGP35348 increased the amplitudes
of the a- and b-wave without having an effect on the
amplitudes of the OPs. The GABAb receptor ligands had
significant and opposite effect on the latency of the OPs. These
results indicate that retinal neurons, presumably a subpopulation of
amacrine cells, that have GABAb receptors are not the source
of the OPs of the ERG, although they may modulate these wavelets in
some manner, while contributing to the generation of the dark-adapted
a- and b-waves. OPs are modified by stimulation of
GABAa receptors, and the a- and b-waves by
stimulation of all GABA receptor subtypes.
Activation of glutamate transporters in rods inhibits presynaptic calcium currents
Authors: RABL KATALIN , BRYSON ERIC J. , THORESON WALLACE B.
Published: January 2004

We found that L-glutamate (L-Glu) inhibits L-type Ca2+currents (ICa) in rod photoreceptors. This inhibition was studied in isolated rods or rods in retinal slices from tiger salamander using perforated patch whole cell recordings and Cl−-imaging techniques. Application of L-Glu inhibitedICaby ∼20% at 0.1 mM and ∼35% at 1 mM. L-Glu also produced an inward current that reversed aroundECl. The metabotropic glutamate receptor (mGluR) agonists t-ADA (Group I), DCG-IV (Group II), and L-AP4 (Group III) had no effect onICa. However, the glutamate transport inhibitor, TBOA (0.1 mM), prevented L-Glu from inhibitingICa. D-aspartate (D-Asp), a glutamate transporter substrate, also inhibitedICawith significantly more inhibition at 1 mM than 0.1 mM. Using Cl−imaging, L-Glu (0.1–1 mM) and D-Asp (0.1–1 mM) were found to stimulate a Cl−efflux from terminals of isolated rods whereas the ionotropic glutamate receptor agonists NMDA, AMPA, and kainate and the mGluR agonist, 1S,3R-ACPD, did not. Glutamate-evoked Cl−effluxes were blocked by the glutamate transport inhibitors TBOA and DHKA. Cl−efflux inhibits Ca2+channel activity in rod terminals (Thoreson et al. (2000),Visual Neuroscience17, 197). Consistent with the possibility that glutamate-evoked Cl−efflux may play a role in the inhibition, reducing intraterminal Cl−prevented L-Glu from inhibitingICa. In summary, the results indicate that activation of glutamate transporters inhibitsICain rods possibly as a consequence of Cl−efflux. The neurotransmitter L-Glu released from rod terminals might thus provide a negative feedback signal to inhibit further L-Glu release.
Development of contour integration in macaque monkeys
Authors: KIORPES LYNNE , BASSIN SARAH A.
Published: January 2004

Studies of visual development show that basic metrics of visual development such as spatial resolution develop over the first 6–9 months in monkeys and over the first 6 or so years in humans. However, more complex visual functions may develop over different, or more protracted, time courses. To address the question of whether global perceptual processing is linked to or otherwise dependent on the development of basic spatial vision, we studied the development of contour integration, a global perceptual task, in comparison to that of grating acuity in macaque monkeys. We find that contour integration develops substantially later than acuity. Contour integration begins to develop at 5–6 months, near the time that acuity development is complete and continues to mature well into the second postnatal year. We discuss this later development in terms poor central efficiency and consider the relevant anatomy and physiology of the developing visual system. We conclude that contour integration is not likely to be limited by the same mechanisms that are permissive to acuity development, and may instead reflect the emergence of function central to V1.
Contour integration in amblyopic monkeys
Authors: KOZMA PETRA , KIORPES LYNNE
Published: January 2004

Amblyopia is characterized by losses in a variety of aspects of spatial vision, such as acuity and contrast sensitivity. Our goal was to learn whether those basic spatial deficits lead to impaired global perceptual processing in strabismic and anisometropic amblyopia. This question is unresolved by the current human psychophysical literature. We studied contour integration and contrast sensitivity in amblyopic monkeys. We found deficient contour integration in anisometropic as well as strabismic amblyopic monkeys. Some animals showed poor contour integration in the fellow eye as well as in the amblyopic eye. Orientation jitter of the elements in the contour systematically decreased contour-detection ability for control and fellow eyes, but had less effect on amblyopic eyes. The deficits were not clearly related to basic losses in contrast sensitivity and acuity for either type of amblyopia. We conclude that abnormal contour integration in amblyopes reflects disruption of mechanisms that are different from those that determine acuity and contrast sensitivity, and are likely to be central to V1.
Bullying als Gruppenphänomen:
Authors: Schäfer Mechthild , Korn Stefan
Published: January 2004

Zusammenfassung. Die Charakterisierung von Opfern und Tätern, die Beschreibung ihrer Beziehungen und die Erfassung möglicher Konsequenzen von systematischer, wiederholter Aggression gegen Schwächere reichen nicht aus, um die Dynamik von Bullying als Problem von Schulklassen darzustellen. Auf Basis des von Salmivalli entwickelten “Participant role“ Ansatzes ( Salmivalli, Lagerspetz, Björkqvist, Österman & Kaukiainen, 1996 ) untersuchten wir 104 Schülern aus vier sechsten Klassen an zwei Hauptschulen und können neun von zehn Schülern eine distinkte Rolle im Bullyingprozess zuordnen. Anhand der sozialen Positionen im Klassengefüge (soziale Präferenz/sozialer Einfluss) und anhand reziproker Beziehungen (Freundschaften) lassen sich Opfer, Verteidiger des Opfers, außenstehende, Täter, Assistent oder Verstärker des Täters unterscheiden. Freundschaften verbinden im Wesentlichen Schüler ohne aggressive Verhaltenstendenzen einerseits und die, die aktiv daran beteiligt sind, dass jemand schikaniert wird andererseits. Implikationen für einen kontextzentrierten Blick auf den Bullyingprozess werden diskutiert.
Stresserleben und Stresssymptomatik bei Kindern und Jugendlichen
Authors: Lohaus Arnold , Beyer Anke , Klein-Heßling Johannes
Published: January 2004

Zusammenfassung. In der vorliegenden Studie wird der Frage nach der Bedeutung von Stresserleben für das Auftreten physischer und psychischer Beschwerden bei Kindern und Jugendlichen nachgegangen. Es wird untersucht, in welchem Ausmaß typische Beanspruchungssymptomatiken von Kindern und Jugendlichen berichtet werden und in welchem Umfang diese Symptomatiken mit Stresserleben in Zusammenhang stehen oder durch andere Einflüsse (wie akute bzw. chronische körperliche Erkrankungen) mitbedingt sein können. Teilnehmer der Untersuchung waren 1.699 Schülerinnen und Schüler der Klassenstufen fünf bis zehn. Die Ergebnisse zeigen, dass sich das Stresserleben und die Beanspruchungssymptomatiken in Abhängigkeit von der Klassenstufe und der Geschlechtszugehörigkeit unterscheiden. Das berichtete Stresserleben und die berichtete physische und psychische Symptomatik steigen mit der Klassenstufe an und Mädchen sehen sich stärker belastet als Jungen. Es finden sich weiterhin systematische Zusammenhänge zwischen dem Ausmaß des Stresserlebens und der von den Schülern berichteten physischen und psychischen Symptomatik. Diese bleiben auch dann noch substantiell bestehen, wenn andere potentielle Einflussparameter (wie Klassenstufe, Geschlecht und vorhandene Erkrankungen der Schüler) herauspartialisiert sind.
Entwicklungsveränderungen des strategischen Gedächtnisses beim Übergang vom Kindergarten in die Grundschule
Authors: Krajewski Kristin , Kron Veronika , Schneider Wolfgang
Published: January 2004

Zusammenfassung. Es werden erste Ergebnisse einer Längsschnittstudie zur Entwicklung des verbalen Gedächtnisses beim Übergang vom Vorschul- in das Grundschulalter beschrieben, die auf den beiden ersten Messzeitpunkten der Studie basieren. Im Mittelpunkt steht dabei die Entwicklung strategischer Kompetenzen am Beispiel semantischer Organisationsaufgaben (sort-recall). Für eine Stichprobe von ca. 100 Kindergartenkindern ließ sich zeigen, dass der Aufbau strategischen Verhaltens von Anfang an eng mit dem Erwerb metakognitiven Wissens verknüpft ist. Im Unterschied zu anderen Gedächtnisaufgaben (Arbeits- oder Textgedächtnis) wurden für den Übergang von der Kindergarten- in die frühe Grundschulphase nur relativ niedrige Langzeitstabilitäten registriert, was als Indiz dafür anzusehen ist, dass sich der Strategie-Erwerb rapide und für unterschiedliche Kinder unterschiedlich schnell vollzieht. Es ließen sich zudem Geschlechtseffekte in dem Sinne nachweisen, dass die Gedächtnisleistung der Mädchen in der semantischen Kategorisierungsaufgabe im Vergleich zu der der Jungen schneller anstieg und zu einem Gedächtnisvorteil bei der zweiten Messung führte.
Galileo plasma spectrometer measurements of composition and temperature in the Io plasma torus
Authors: Crary F. J. , Bagenal F. , Frank L. A. , Paterson W. R.
Published: February 2004

On December 7, 1995, the Galileo spacecraft passed through the Io plasma torus, and made observations of this dense, heavy ion plasma. We report an analysis of the data from the spacecraft's plasma spectrometer which measures the angular distribution of the ions. This enables us to determine the composition of the plasma. We compare our results to the models based on the Voyager 1 encounter of 1979, Galileo ultraviolet observations, and Earth‐based observations. At the time and longitude of the December 7 Galileo encounter the abundance of oxygen was higher than observed by Voyager, and the O++:O+ ratio was greater. The ion temperatures were not in thermal equilibrium and were generally cooler than Voyager values.
Role of lower hybrid turbulence in surfing acceleration at perpendicular shocks
Authors: Shapiro V. D. , Lee M. A. , Quest K. B.
Published: January 2004

The mechanism for excitation of lower hybrid waves by shock surfing pickup ions is proposed. It is based on the modified two‐stream instability. The stationary distribution function of the surfing particles is calculated, which can serve as a driver for the excitation of the lower hybrid waves. The instability growth rate is found, as well as conditions under which waves have enough time to grow while being convected to the shock front together with the solar wind flow. The excited waves are responsible for the velocity diffusion of the surfing particles in the direction opposite to the acceleration. These particles are detrapped from the shock front and escape from the shock surfing acceleration. The flux of escaping particles is calculated in the quasi‐linear approximation, and it is shown to decrease quickly with the mass of the accelerated particles. This result can provide a possible explanation of Voyager observations, which indicate that the injection efficiency of interstellar pickup into the acceleration process at the solar wind termination shock increases significantly for heavy ions in comparison with hydrogen.
Comparison of magnetic field models to magnetospheric cusp positions observed by the Polar magnetometer
Authors: Henize V. K. , Reiff P. H. , Urquhart A. L. , Toffoletto F. R. , Russell C. T.
Published: January 2004

This paper examines the relation between known crossings of the equatorward edge of the Earth's northern magnetic cusp during steady southward interplanetary magnetic field conditions, as recorded by the Magnetic Field Experiment onboard the Polar spacecraft, and the predicted location of the equatorwardmost open field line as given by two differing magnetic field models. These are the Rice Field Model, an analytic open magnetosphere field model; and the Tsyganenko 1996 data‐based model. The two models that were considered display remarkably similar performance in how often they can locate the dayside equatorward edge of the cusp in three dimensions. However, the Rice Field Model is superior for ZGSM > 5 RE, whereas the Tsyganenko 1996 model more accurately duplicates the observed range of cusp positions in the YGSM direction. The Rice Field Model and the Tsyganenko 1996 models also differ in predicting the magnetic field vectors in and around the cusp region. The former is more accurate at high latitudes on closed dayside field lines equatorward of the cusp; the latter is better at predicting the field direction on interconnected field lines.
Thermal coupling of protons and neutral hydrogen with anisotropic temperatures in the fast solar wind
Authors: Allen Lorraine A. , Habbal Shadia R. , Li Xing
Published: February 2004

The thermal coupling between the neutral hydrogen and protons in the inner corona is explored by extending the study of Allen et al. [1998] to include anisotropic proton temperature to determine what the neutral hydrogen Ly α spectral line measurements reveal about the proton temperature, temperature anisotropy, and outflow velocity in the fast solar wind. The anisotropic proton temperature is produced by ion cyclotron resonant interaction of protons with high‐frequency waves, produced by a nonlinear cascade at the Kolmogorov dissipation rate from dominant lower‐frequency Alfvén waves. As a result of the coupling between the respective parallel and perpendicular components of the neutral hydrogen and proton temperatures, a greater temperature anisotropy in the neutral hydrogen develops as compared to the case when the proton temperature is isotropic. The neutral hydrogen and proton effective temperatures (Teff), incorporating both random and wave motions of the particles, and outflow velocities, are comparable below ∼ 3 Rs. Neutral hydrogen anisotropy ratios, TH(eff)/T‖, ∼ 4 below 3 Rs are readily attained, in agreement with observations. Below ∼ 3 Rs, these reflect the proton anisotropy ratio. For plasma conditions typical of the fast solar wind, these results imply that the measured Ly α spectral line profiles, from which the neutral hydrogen temperature, anisotropy ratio, and outflow velocity are inferred, are equivalent to measurements of protons below ∼ 3 Rs. Beyond this distance the width of the measured Ly α spectral lines provides a lower limit to the proton effective temperature and temperature anisotropy in the inner corona.
Primary productivity in the equatorial Pacific during the 1997–1998 El Niño
Authors: Strutton Peter G. , Chavez Francisco P.
Published: February 2004

Shipboard biological and physical measurements made during 1996, 1997, and 1998 in the equatorial Pacific are used to quantify the effect of the 1997–1998 El Niño on the phytoplankton community. This El Niño was by some measures the strongest ever observed and resulted in extremely low phytoplankton biomass and productivity throughout this normally moderately productive region. At the height of the event in late 1997 to early 1998, in the central Pacific, nitrate was absent throughout the entire euphotic zone (∼100 m), resulting in chlorophyll concentrations (0.05 μgL−1) that were among the lowest ever observed in the region and rates of primary production (∼0.41 g C m−2 d−1) that were approximately half the climatological mean. These conditions persisted until May 1998 when the trade winds resumed and upwelling, with its associated supply of nutrients, was restored along the equatorial Pacific. The phytoplankton community quickly recovered, and by June 1998, nitrate, chlorophyll, and primary productivity levels were comparable to, or in excess of, their respective climatological means.