bluuebunny/crossref_metadata_2025 huggingface dataset:
γ-Sarcoglycan deficiency increases cell contractility, apoptosis and MAPK pathway activation but does not affect adhesion
Authors: Griffin Maureen A. , Feng Huisheng , Tewari Manorama , Acosta Pedro , Kawana Masataka , Sweeney H. Lee , Discher Dennis E.
Published: March 2005

The functions of γ-sarcoglycan (γSG) in normal myotubes are largely unknown, however γSG is known to assemble into a key membrane complex with dystroglycan and its deficiency is one known cause of limb-girdle muscular dystrophy. Previous findings of apoptosis from γSG-deficient mice are extended here to cell culture where apoptosis is seen to increase more than tenfold in γSG-deficient myotubes compared with normal cells. The deficient myotubes also exhibit an increased contractile prestress that results in greater shortening and widening when the cells are either lightly detached or self-detached. However, micropipette-forced peeling of single myotubes revealed no significant difference in cell adhesion. Consistent with a more contractile phenotype, acto-myosin striations were more prominent in γSG-deficient myotubes than in normal cells. An initial phosphoscreen of more than 12 signaling proteins revealed a number of differences between normal and γSG–/– muscle, both before and after stretching. MAPK-pathway proteins displayed the largest changes in activation, although significant phosphorylation also appeared for other proteins linked to hypertension. We conclude that γSG normally moderates contractile prestress in skeletal muscle, and we propose a role for γSG in membrane-based signaling of the effects of prestress and sarcomerogenesis.
Effect of Walker A mutation (K86M) on oligomerization and surface targeting of the multidrug resistance transporter ABCG2
Authors: Henriksen Ulla , Gether Ulrik , Litman Thomas
Published: March 2005

The ATP binding cassette (ABC) half-transporter ABCG2 (MXR/BCRP/ABCP) is associated with mitoxantrone resistance accompanied by cross-resistance to a broad spectrum of cytotoxic drugs. Here we investigate the functional consequences of mutating a highly conserved lysine in the Walker A motif of the nucleotide binding domain (NBD) known to be critical for ATP binding and/or hydrolysis in ABC transporters. The mutant (ABCG2-K86M) was inactive as expected but was expressed at similar levels as the wild-type (wt) protein. The mutation did not affect the predicted oligomerization properties of the transporter; hence, co-immunoprecipitation experiments using differentially tagged transporters showed evidence for oligomerization of both ABCG2-wt and of ABCG2-wt with ABCG2-K86M. We also obtained evidence that both ABCG2-wt and ABCG2-K86M exist in the cells as disulfide-linked dimers. Moreover, measurement of prazosin-stimulated ATPase activity revealed a dominant-negative effect of ABCG2-K86M on ABCG2-wt function in co-transfected HEK293 cells. This is consistent with the requirement for at least two active NBDs for transporter activity and suggests that the transporter is a functional dimer. Finally, we analyzed targeting of ABCG2-wt and ABCG2-K86M and observed that they localize to two distinct subcellular compartments: ABCG2-wt targets the cell surface whereas ABCG2-K86M is targeted to the Golgi apparatus followed by retrieval to the endoplasmic reticulum. This suggests an as yet unknown role of the NBDs in assisting proper surface targeting of ABC transporters.
The N-terminal Ac-EEED sequence plays a role in α-smooth-muscle actin incorporation into stress fibers
Authors: Clément Sophie , Hinz Boris , Dugina Vera , Gabbiani Giulio , Chaponnier Christine
Published: March 2005

We have previously shown that the N-terminal sequence AcEEED of α-smooth-muscle actin causes the loss of α-smooth-muscle actin from stress fibers and a decrease in cell contractility when introduced in myofibroblasts as a cell-penetrating fusion peptide. Here, we have investigated the function of this sequence on stress fiber organization in living cells, using enhanced green fluorescent protein (EGFP)-tagged α-smooth-muscle actin. The fusion peptide provokes the gradual disappearance of EGFP fluorescence of α-smooth-muscle actin from stress fibers and the formation of hitherto unknown rod-like structures. In addition to α-smooth-muscle actin, these structures contain cytoplasmic actins, gelsolin and cofilin but not other major actin-binding proteins. These rod-like structures are also visible in wild-type fibroblasts during normal cell spreading, suggesting that they represent a physiological step in the organization of α-smooth-muscle actin in stress fibers. Fluorescence-recovery-after-photobleaching experiments suggest that the fusion peptide reduces the dynamics of α-smooth-muscle actin and its incorporation in stress fibers. Here, we propose a new mechanism of how α-smooth-muscle actin is incorporated in stress fibers involving the sequence Ac-EEED.
A novelSry-downstream cellular event which preserves the readily available energy source of glycogen in mouse sex differentiation
Authors: Matoba Shogo , Kanai Yoshiakira , Kidokoro Tomohide , Kanai-Azuma Masami , Kawakami Hayato , Hayashi Yoshihiro , Kurohmaru Masamichi
Published: March 2005

Sry is transiently activated in pre-Sertoli cells of the gonadal ridge to initiate testis differentiation in mice. In pre-Sertoli cells, however, the cellular events induced immediately after the onset of Sry expression remain largely unknown. Here we show that testis-specific glycogen accumulation in pre-Sertoli cells is one of the earliest cellular events downstream of Sry action. In developing XY gonads, glycogen accumulation starts to occur in pre-Sertoli cells from around 11.15 dpc (tail somite 14 stage) in a center-to-pole pattern similar to the initial Sry expression profile. Glycogen accumulation was also found in XX male gonads of Sry-transgenic embryos, but not in XX female gonads of wildtype embryos at any developmental stage. In vitro analyses using various culture conditions suggest that testis-specific glycogen deposition is a tissue-autonomous event that can be induced even in serum-free conditions and in a culture of gonadal explants without adjacent mesonephros. Moreover, glycogen accumulation in pre-Sertoli cells was significantly inhibited in vitro by the PI3K inhibitor LY294002, but not by the MEK inhibitor PD98059. Active phospho-AKT (PI3K effector) showed a high degree of accumulation in gonadal somatic cells of genital ridges in a testis-specific manner, both in vitro and in vivo. Therefore, these findings suggest that immediately after the onset of Sry expression, activation of the PI3K-AKT pathway promotes testis-specific glycogen storage in pre-Sertoli cells. To the best of our knowledge, this is a novel Sry-downstream cellular event which preserves this readily available energy source in Sertoli cells for testis-specific morphogenesis and hormone production.
Market Orientation: A Meta-Analytic Review and Assessment of its Antecedents and Impact on Performance
Authors: Kirca Ahmet H. , Jayachandran Satish , Bearden William O.
Published: March 2005

The authors conduct a meta-analysis that aggregates empirical findings from the market orientation literature. First, the study provides a quantitative summary of the bivariate findings regarding the antecedents and the consequences of market orientation. Second, the authors use multivariate analyses of aggregate study effects to identify significant antecedents of market orientation and the process variables that mediate the relationship between market orientation and performance. In addition, using regression analysis, the authors find that the market orientation–performance relationship is stronger in samples of manufacturing firms, in low power-distance and uncertainty-avoidance cultures, and in studies that use subjective measures of performance. The authors also find that the market orientation–performance correlation is stronger for both cost-based and revenue-based performance measures in manufacturing firms than in service firms. On the basis of the findings, the authors conclude with a discussion of the implications for practice and further research.
Evaluation of Some Adjuvants for Improving Glyphosate Efficacy
Authors: Singh S , Singh M
Published: March 2005

Glyphosate is the most common non-selective post-emergence herbicide used under diverse conditions. The efficacy of foliar applied herbicides is greatly influenced by adjuvants, but not all adjuvants have a synergistic effect. Greenhouse experiments were conducted using weed species of Echinochola crus-galli, Panicum maximum, Bidens pilosa, and Abutilon theophrasti to evaluate glyphosate efficacy by tank mixing with 0.5 % of Blaze®, Condition®, Improve®, and Induce®. Glyphosate at 0, 0.14, 0.28, and 0.56 kg ae/ha alone and with adjuvants was sprayed at the 4 leaf stage of weeds. Surface tension and contact angle were measured under lab conditions.

Adjuvants increased the activity of glyphosate by 15–29 % compared to glyphosate alone. Among the weed species, higher mortality was observed in P. maximum and B. pilosa followed by E. crus-galli and lowest in A. theophrasti. On mortality of grass and broadleaf weed species, significant differences were observed by tank mixing glyphosate with different adjuvants. Lowest Contact Angle (CA) and Surface Tension (ST) were recorded when glyphosate (Rodeo®, with no surfactant) was mixed with Improve and Blaze surfactants, which was significantly lower than glyphosate formulation pre-mixed with surfactant (Roundup UltraMax®). In the case of Condition, the relative decrease in CA was less than ST when added to glyphosate, compared to Improve and Blaze. Lower ST and CA of glyphosate tank mixed with Improve and Blaze correlated with improved weed mortality in the activity study.
Improving the Effectiveness of Aerial Pesticide Sprays
Authors: Smith DB , Kirk IW , Ross JB
Published: March 2005

Thirty-eight aircraft setups were submitted in order to have droplet size and drift analyses performed. Four of the eleven insecticides predicted Dv0.5s were in the 351–400 µm range. Seven of the herbicide setups had predicted Dv0.5s in the 205–250 µm range, while ten Dv0.5s were > 351 µm. Five of the ten predicted Dv0.5s were between 386 and 413 μm. Twelve different herbicides were reported as having been applied with aircraft setups that had predicted Dv0.5s between 386 and 413 µm. A summary of the prior swath deposit data indicated that the percent recovery generally increased as the Dv0.5 increased. The magnitudes of the deposits on inert targets and cotton leaves appeared to be about equal for a given Dv0.5. The correlation coefficient between the “percent of the spray volume in droplets ≤100 µm and ≤200 µm in diameter” was 0.983. This result is consistent with prior results and indicates that either 100 or 200 µm can be effectively used as the upper limit when studying the “small droplet” component in sprays. We found several similarities or differences in the “small droplet” components based on data from different atomization tests. According to one set of atomization models, agricultural aircraft will be limited to about 225 km/h (i.e., 140 mph) in order to produce a 400 µm Dv0.5 spray when using currently available nozzles and water plus one or more pesticides. The extremes of the predicted drift deposits for 38 agricultural aircraft setups were over 30-fold apart.
Evaluation of Quartz Residue on Cassette Interiors of AIHA Proficiency Samples
Authors: Dobson LR , Reichmann L , Popp D
Published: March 2005

Air generated quartz samples have been used for many years in the American Industrial Hygiene Association (AIHA) Proficiency Analytical Testing (PAT) program. It has been observed by the Wisconsin Occupational Health Laboratory (WOHL) that there is material adhering to the cassette interior of several PAT samples. WOHL has collected data on this problem for a number of AIHA PAT rounds and found that the cassette tops can contain a significant amount of quartz. Using data collected from PAT Rounds 146–155, it was found that half of the samples contained quartz on the cassette interior above the WOHL reporting level (RL) of 10 µg. The quartz on the cassette interior is one possible explanation for some of the performance issues found in laboratories participating in the AIHA PAT proficiency program. This problem is not unique to PAT samples. WOHL has noticed the same issue with field samples, which can lead to lower levels of quartz being reported.
Overload Fracture of Flaw Tip Hydrides in Zr-2.5Nb Pressure Tubes
Authors: Shek GK , Cui J , Perovic V
Published: March 2005

CANDU Zr-2.5Nb pressure tubes are susceptible to a crack initiation mechanism known as Delayed Hydride Cracking (DHC), which is a process that involves hydrogen diffusion, hydride precipitation, hydride region formation, and fracture at a flaw tip. An overload occurs when the hydrided region is loaded to a stress higher than that at which this region is formed. Service-induced flaws are present in some pressure tubes, which can act as crack initiation sites. Most experimental data to assess DHC initiation are obtained under constant loading conditions in which hydride formation and fracture occur at the same load, and therefore they are not suitable to assess crack initiation under overload condition. A series of step-wise increasing load experiments was performed on unirradiated Zr-2.5Nb pressure tube samples to determine the fracture stress of hydrides formed at notches with 15 μm root radius under different hydride formation stresses and thermal histories. Crack initiation in the overload tests was detected by the acoustic emission technique. The notch tip hydride morphologies were examined by optical and scanning electron microscopy. Test results indicated that the resistance to overload fracture was dependent on the hydride formation stress and thermal histories, which affected the notch tip hydride size, density, and distribution. Overload tests were performed at different temperatures, and a transition temperature to high resistance to overload fracture was observed.
Data Security Issues Relating to End of Life Equipment
Authors: Bennison PF , Lasher PJ
Published: March 2005

Data security is obviously becoming more important for anyone involved in computer security. Encryption methods have become more advanced over the years, and there are plenty of tools available that will prevent intruders from accessing confidential data on an active network. However, one of the easiest methods for would-be attackers to gather confidential information is by recovering data from discarded computer hardware or other storage media. This paper covers security concerns related to end of life computer equipment and methods for properly destroying information so it cannot be recovered.
The Rod Photoreceptor Pattern Is Set at the Optic Vesicle Stage and Requires Spatially RestrictedcVaxExpression
Authors: Schulte Dorothea , Peters Maureen A. , Sen Jonaki , Cepko Constance L.
Published: March 2005

How and when positional identities in the neural retina are established have been addressed primarily with respect to the topographic projections of retinal ganglion cells onto their targets in the brain. Although retinotectal map formation is a prominent manifestation of retinal patterning, it is not the only one. Photoreceptor subtypes are arranged in distinct, species-specific patterns. The mechanisms used to establish photoreceptor patterns have been relatively unexplored at the mechanistic level. We performed ablations of the eye anlage in chickens and found that removal of the anterior or dorsal optic vesicle caused loss of the area centralis, which is a rod-free central area of the retina, and severely disorganized other aspects of the rod pattern. These observations indicate that the anteroposterior and dorsoventral distribution of rods is determined by the optic vesicle stage. To investigate the molecular mechanisms involved, the rod distribution was analyzed after viral misexpression of several patterning genes that were previously shown to be important in positional specification of retinal ganglion cells. Ectopic expression ofFoxG1,SOHo1,orGH6transcription factors expressed in the anterior optic vesicle and/or optic cup, respectively, did not affect the rod pattern. This pattern therefore appears to be specified by an activity acting before, or in parallel with, these factors. In contrast, misexpression of the ventrally restricted transcription factor,cVax, severely disturbed the rod pattern.
Recovery of Myelin after Induction of Oligodendrocyte Cell Death in Postnatal Brain
Authors: Jalabi Walid , Boehm Nelly , Grucker Daniel , Ghandour M. Said
Published: March 2005

A transgenic mouse line (Oligo-TTK) was established to monitor oligodendrocyte cell death and myelin formation in the CNS. The expression of a conditionally toxic gene, the herpes simplex virus-1 thymidine kinase (HSV1-TK), was made under control of the MBP (myelin basic protein) gene promoter. A truncated form of the HSV1-TK (TTK) gene was used to avoid both bystander effect resulting from leaking in thymidine kinase activity and sterility in transgenic males observed in previous transgenic mice. The transgene was expressed in the CNS with a restricted localization in oligodendrocytes. Oligodendrocyte proliferation and myelin formation are therefore tightly controlled experimentally by administration of ganciclovir (GCV) via the induction of oligodendrocyte cell death. The most severe and irreversible hypomyelination was obtained when GCV was given daily from postnatal day 1 (P1) to P30. Oligodendrocyte plasticity and myelin recovery were analyzed in another phenotype generated by GCV treatment from P1 to P15. In this model, after dysmyelination, an apparent normal behavior was restored with no visible pathological symptoms by P30. Proliferating cells, which may be implicated in myelin repair in this model, are detected primarily in myelin tracts expressing the oligodendrocyte phenotype. Therefore, the endogenous potential of oligodendrocytes to remyelinate was clearly demonstrated in the mice of this study.
Lesion to the Nigrostriatal Dopamine System Disrupts Stimulus-Response Habit Formation
Authors: Faure Alexis , Haberland Ulrike , Condé Françoise , Massioui Nicole El
Published: March 2005

Acquisition and performance of instrumental actions are assumed to require both action-outcome and stimulus-response (S-R) habit processes. Over the course of extended training, control over instrumental performance shifts from goal-directed action-outcome associations to S-R associations that progressively gain domination over behavior. Lesions of the lateral part of the dorsal striatum disrupt this process, and rats with lesions to the lateral striatum showed selective sensitivity to devaluation of the instrumental outcome (Yin et al., 2004), indicating that this area is necessary for habit formation. The present experiment further explored the basis of this dysfunction by examining the ability of rats subjected to bilateral 6-hydroxydopamine lesions of the nigrostriatal dopaminergic pathway to develop behavioral autonomy with overtraining. Rats were given extended training on two cued instrumental tasks associating a stimulus (a tone or a light) with an instrumental action (lever press or chain pull) and a food reward (pellets or sucrose). Both tasks were run daily in separate sessions. Overtraining was followed by a test of goal sensitivity by satiety-specific devaluation of the reward. In control animals, one action (lever press) was insensitive to reward devaluation, indicating that it became a habit, whereas the second action (chain pull) was still sensitive to goal devaluation. This result provides evidence that the development of habit learning may depend on the characteristics of the response. In dopamine-depleted rats, lever press and chain pull remained sensitive to reward devaluation, evidencing a role of striatal dopamine transmission in habit formation.
Context-Dependent Modulation of Movement-Related Discharge in the Primate Globus Pallidus
Authors: Turner Robert S. , Anderson Marjorie E.
Published: March 2005

A selective contribution of the basal ganglia (BG) to memory-contingent motor control has long been hypothesized. The importance of memory context remains an open question, however, for the BG skeletomotor circuit. To investigate this question, we studied the perimovement discharge of a carefully selected group of 74 “arm-related” pallidal cells in two rhesus monkeys. The animals performed three tasks designed to dissociate multiple independent aspects of memory-contingent reaching while controlling movement kinematics. The activity of most neurons (88%) was influenced strongly by the memory demands of a task (remembering “where” or “when” to move), but the population as a whole showed no systematic preference for memory- or sensory-contingent conditions. The effects of memory context were primarily additive with those of movement kinematics (particularly movement direction). Considered separately, decreases and increases in firing had very different context preferences: decreases were nearly always larger for sensory-triggered movements, whereas increases were enhanced most often under memory-contingent conditions (i.e., self-initiated or self-guided movements). A similar pattern of preferences was found for both pallidal segments. The distinct context-specific enhancements of decreases and increases could not be explained as simple sensory responses or as interactions with preparatory or anticipatory processes present before movement initiation. Rather, they appear related to movement execution under specific contexts. Our results lead to the conclusion that movement facilitatory decreases in internal pallidal (GPi) activity are primarily greater under sensory-triggered conditions. GPi increases and their suppressive effects, perhaps on competing activity in pallidal-recipient centers, have increased prevalence under memory-contingent conditions.
Tangential Networks of Precocious Neurons and Early Axonal Outgrowth in the Embryonic Human Forebrain
Authors: Bystron Irina , Molnár Zoltán , Otellin Vladimir , Blakemore Colin
Published: March 2005

We used a combination of immunohistochemistry and carbocyanine dye tracing to study neurons and their processes in the human embryonic forebrain, 4-7 weeks after conception, before the onset of synaptogenesis. We discovered a widespread network of precocious MAP2 (microtubule-associated protein 2)-immunoreactive cells, with long, nonaxonal processes, before the appearance of the cortical plate and the establishment of thalamocortical connectivity. Dye tracing revealed that the processes of these precocious cells form tangential links between intermediate zones of the thalamus, ganglionic eminence, hypothalamus, and cortical preplate. The spatiotemporal distribution and morphology of the precocious neurons in the cortical preplate suggest that they are generated outside the cerebral wall rather than in the local ventricular zone. The first thalamocortical axons and axons of preplate cells extend across diencephalo-telencephalic and striatocortical boundaries before the arrival of the first cortical plate neurons. Precocious cells may provide initial communication between subdivisions of the embryonic brain as well as guidance cues for navigation of growing axons and/or transverse neuronal migration.
Detecting Activity in Olfactory Bulb Glomeruli with Astrocyte Recording
Authors: De Saint Jan Didier , Westbrook Gary L.
Published: March 2005

In the olfactory bulb, axons of olfactory sensory neurons (OSNs) expressing the same olfactory receptor converge on specific glomeruli. These afferents form axodendritic synapses with mitral/tufted and periglomerular cell dendrites, whereas the dendrites of mitral/tufted cells and periglomerular interneurons form dendrodendritic synapses. The two types of intraglomerular synapses appear to be spatially isolated in subcompartments delineated by astrocyte processes. Because each astrocyte sends processes into a single glomerulus, we used astrocyte recording as an intraglomerular detector of neuronal activity. In glomerular astrocytes, a single shock in the olfactory nerve layer evoked a prolonged inward current, the major part of which was attributable to a barium-sensitive potassium current. The K+current closely reflected the time course of depolarization of mitral/tufted cells, indicating that K+accumulation mainly reflects the activity of mitral/tufted cells. The astrocyte K+current was dependent on AMPA and NMDA receptors in mitral/tufted cells as well as on a previously undescribed metabotropic glutamate receptor 1 component. Block of the K+current with barium unmasked a synaptic glutamate transporter current. Perhaps surprisingly, the transporter current had components caused by glutamate released at both olfactory nerve terminals and mitral/tufted cell dendrites. The time course of the transporter currents suggested that rapid synchronous glutamate release at OSN terminals triggers asynchronous glutamate release from mitral/tufted cells. Glomerular astrocyte recording provides a sensitive means to examine functional compartmentalization within and between olfactory bulb glomeruli.
Separating the Brain Regions Involved in Recollection and Familiarity in Recognition Memory
Authors: Yonelinas Andrew P. , Otten Leun J. , Shaw Kendra N. , Rugg Michael D.
Published: March 2005

The neural substrates of recognition memory retrieval were examined in a functional magnetic resonance imaging study designed to separate activity related to recollection from that related to continuous variations in familiarity. Across a variety of brain regions, the neural signature of recollection was found to be distinct from familiarity, demonstrating that recollection cannot be attributed to familiarity strength. In the prefrontal cortex, an anterior medial region was related to recollection, but lateral regions, including the anterior and dorsolateral prefrontal cortex, were related to familiarity. Along the lateral parietal cortex, two functionally distinct regions were also observed: a lateral parietal/temporal region related to recollection and a more superior parietal region involved in familiarity. Similarly, in medial parietal regions, the posterior cingulate was related to recollection, whereas the precuneus was related to familiarity. The hippocampus was related to recollection, but also exhibited an inverse relationship to familiarity-driven recognition confidence. The results indicate that recollection and familiarity rely on different networks of brain regions and provide insights into the functional roles of different regions involved in episodic recognition memory.
Geminal Functional Theory
Authors: Rinderspacher B Christopher , Schreiner Peter R
Published: March 2005

Geminal functional theory exploits the structure of the Hamiltonian operator in the Schrödinger equation, greatly reducing the computational complexity of the problem. Several approaches have been developed –
strongly orthogonal antisymmetrized geminal products
(SOAGP), singlet‐type strongly orthogonal geminal products,
antisymmetrized geminal products
(AGPs) of
one
geminal, and a general minimum search of the second order reduced density matrix space based on AGPs. Furthermore, SOAGPs have been employed as reference wave functions for perturbation theory.
Nanopartikel in der Energietechnik – Beispiele aus der Elektrochemie und Katalyse
Authors: Raimondi Fabio , Scherer Günther G. , Kötz Rüdiger , Wokaun Alexander
Published: March 2005

Nanopartikel sind Schlüsselkomponenten bei der Entwicklung künftiger Energietechnologien, sodass besondere Strategien notwendig sind, die eine kosteneffiziente Produktion von Nanopartikeln für Massenanwendungen gewährleisten. Eine wichtige Rolle kommt nanometergroßen Partikeln beim Ersatz fossiler Brennstoffe durch erneuerbare Energiequellen zu, speziell bei der Herstellung von Energievektoren aus variablen und heterogenen Biomassereservoirs. Nanopartikel werden in Reformern für die Produktion von Wasserstoff aus festen, flüssigen oder gasförmigen Energieträgern eingesetzt, wobei die Katalysatoraktivität eine ausgeprägte Größenabhängigkeit zeigt. Sie sind als Elektrokatalysatoren in Brennstoffzellen und anderen elektrochemischen Konvertern unverzichtbar. Mit dem Ziel, höhere Aktivitäten pro Flächeneinheit zu erzielen und mit geringeren Mengen des teuren katalytischen Standardmaterials Platin auszukommen, wurden nasschemische und kolloidale Verfahren sowie physikalische Techniken wie Sputtern entwickelt, die zur Synthese von aus Platinlegierungen bestehenden Nanopartikeln angewendet werden.
Putting it together online: Information need identification for the domain novice user
Authors: Cole Charles , Leide John E. , Large Andrew , Beheshti Jamshid , Brooks Martin
Published: March 2005

Domain novice users in the beginning stages of researching a topic find themselves searching for information via information retrieval (IR) systems before they have identified their information need. Pre‐Internet access technologies adapted by current IR systems poorly serve these domain novice users, whose behavior might be characterized as rudderless and without a compass. In this article we describe a conceptual design for an information retrieval system that incorporates standard information need identification classification and subject cataloging schemes, called the INIIReye System, and a study that tests the efficacy of the innovative part of the INIIReye System, called the Associative Index. The Associative Index helps the user put together his or her associative thoughts—Vannevar Bush's idea of associative indexing for his Memex machine that he never actually described. For the first time, data from the study reported here quantitatively supports the theoretical notion that the information seeker's information need is identified through transformation of his/her knowledge structure (i.e., the seeker's cognitive map or perspective on the task for which information is being sought).
The power of power laws and an interpretation of Lotkaian informetric systems as self‐similar fractals
Authors: Egghe L.
Published: March 2005

Power laws as defined in 1926 by A. Lotka are increasing in importance because they have been found valid in varied social networks including the Internet. In this article some unique properties of power laws are proven. They are shown to characterize functions with the scale‐free property (also called self‐similarity property) as well as functions with the product property. Power laws have other desirable properties that are not shared by exponential laws, as we indicate in this paper. Specifically, Naranan (1970) proves the validity of Lotka's law based on the exponential growth of articles in journals and of the number of journals. His argument is reproduced here and a discrete‐time argument is also given, yielding the same law as that of Lotka. This argument makes it possible to interpret the information production process as a self‐similar fractal and show the relation between Lotka's exponent and the (self‐similar) fractal dimension of the system. Lotkaian informetric systems are self‐similar fractals, a fact revealed by Mandelbrot (1977) in relation to nature, but is also true for random texts, which exemplify a very special type of informetric system.
Speech perception as a window for understanding plasticity and commitment in language systems of the brain
Authors: Werker Janet F. , Tees Richard C.
Published: March 2005

In this article, we provide a critical review of the literature on speech perception and phonological processing in infancy, and in populations with different experiential histories as a window to understanding how the notion of critical periods might apply to the acquisition of one part of language: the sound system. We begin by suggesting the use of the term “optimal period” because (a) both the onset (opening) and offset (closing) of openness to experience is variable rather than absolute and (b) phonological acquisition involves the emergence of a series of nested capabilities, each with its own sensitive period and each best explained at one of several different levels of specificity. In support, we cite evidence suggesting that to fully understand plasticity and commitment in phonological acquisition, it is necessary to consider not only the biological and experiential factors which may contribute to the onset and the offset of openness to experience but also how the sequentially developing parts of phonology constrain and direct development. In summary, we propose a nested, cascading model wherein biology, experience, and functional use each contribute. © 2005 Wiley Periodicals, Inc. Dev Psychobiol 46: 233–251, 2005.
Stereodivergent Syntheses of Highly Substituted Enantiopure 4‐Alkoxy‐3,6‐dihydro‐2H‐1,2‐oxazines by Addition of Lithiated Alkoxyallenes to Carbohydrate‐Derived Aldonitrones
Authors: Helms Matthias , Schade Wolfgang , Pulz Robert , Watanabe Toshiko , Al‐Harrasi Ahmed , Fišera Lubor , Hlobilová Iva , Zahn Gernot , Reißig Hans‐Ulrich
Published: March 2005

Additions of lithiated alkoxyallenes to D‐glyceraldehyde‐based nitrones 1 and 2 did not provide the expected hydroxylamine derivatives. Instead, a novel [3+3] cyclization process furnished 4‐alkoxy‐3,6‐dihydro‐2H‐1,2‐oxazines 9–14 with excellent syn selectivities and in moderate to good yields. Through precomplexation of the nitrones the corresponding anti‐configured 1,2‐oxazines 9, 10 and 13 could be obtained with high stereoselectivity. The reactions of nitrones 3–6, derived from D‐erythrose or D‐threose, generally proceeded less diastereoselectively, but reasonable yields of anti‐configured 1,2‐oxazines such as anti‐17 and anti‐19 could be obtained under Lewis acid promotion conditions. This was also the case for reactions of the D‐arabinose‐derived nitrone 7, which provided the anti‐1,2‐oxazines 23 and 24 with excellent diastereoselectivity and in good yields. Bis‐nitrone 8 and lithiated methoxyallene furnished a mixture of six compounds, among which the major componentwas the C2‐symmetric syn/syn‐1,2‐oxazine 29. The diastereoselectivities of these reactions are interpreted on the basis of Dondoni’s model for reactions between organolithium compounds and nitrones. The mechanisms for formation of 1,2‐oxazines and of side products are discussed. The method introduced here seems to be of broad applicability and an excellent tool for diastereoselective chain elongation of carbohydrate derivatives, affording stereodefined precursors of aminopolyols and other highly functionalized compounds. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Facially Controlled C‐Methylation of Oxolanyl and Cyclopentyl Acetate Enolates: Application to the Total Synthesis of (+)‐Nephromopsinic Acid
Authors: Mulzer Johann , Steffen Ulrich , Martin Harry J. , Zorn Ludwig
Published: March 2005

The stereoselectivity of the C‐methylation of oxolanyl and cyclopentyl acetate enolates 5a–22a was investigated. The configuration of the C‐methyl diastereomers was elucidated by a combination of crystal structure analysis, NMR spectroscopy and chemical correlations. Generally, the methylation proceeded re*‐selectively, although with very different degrees of selectivity. The most important stereodirecting effect was a steric one exerted by the 5‐phenethyl substituent, and this steric effect was strongly increased by the stereodirecting effect of a 3‐OR group. Contrary to previous literature evidence, the endocyclic oxolanyl oxygen does not exert an effect. These findings were applied in a highly stereoselective synthesis of (+)‐nephromopsinic acid (94). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Cycloaddition Reactions of Phosphorylated 1,2‐Diaza‐1,3‐butadienes with Olefins: Regioselective Synthesis of Pyridazine Derivatives
Authors: Palacios Francisco , Aparicio Domitila , López Yago , de los Santos Jesús M. , Alonso Concepción
Published: March 2005

The aza‐Diels–Alder reaction of 4‐phosphinyl‐ and 4‐phosphonyl‐1,2‐diaza‐1,3‐butadienes with styrene, cyclopentadiene, dihydrofuran and norbornadiene is reported. Monocyclic, bicyclic and polycyclic tetrahydropyridazines containing a phosphane oxide or a phosphonate substituent are obtained. The formation of cycloadducts can be explained by an endo transition state in the cycloaddition process of these heterodienes with styrene, cyclopentadiene, dihydrofuran, and by means of an exo transition state in the case of norbornadiene. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Towards Benign Synthesis of Indenes from Indanones: Zinc‐Mediated Allylation of Ketones in Aqueous Media as a Source of Substituted Indenyl Ligand Precursors
Authors: Silver Satu , Leppänen Ann‐Sofie , Sjöholm Rainer , Penninkangas Antti , Leino Reko
Published: March 2005

Substituted indenes are valuable ligand precursors for transition‐metal complexes. Previously, most of the methods employed for the preparation of alkyl‐substituted indenes have involved the use of air‐sensitive organometallic lithium or Grignard reagents, often in combination with expensive metal catalysts. The present work evaluates an approach to the synthesis of 2‐ and 3‐allyl‐substituted indenes by employing a simple, environmentally benign organometallic zinc‐mediated Barbier‐type allylation of 1‐ and 2‐indanones in aqueous media. A large series of new achiral and racemic indenyl ligand precursors have been prepared in variable yields byreacting substituted and unsubstituted indanones with allyl‐,crotyl‐, and cinnamyl halides using metallic zinc as the me‐diating metal in THF/NH4Claq followed by acid‐catalyzed dehydration. The method described is applicable also for indanones containing unprotected halide‐ and hydroxyl substituents. As an example of extension of the approach, some indenes have been further hydrosilylated with achiral silanes and disilanes in the presence of Karstedt’s catalyst to provide new silaalkyl‐substituted indenes and bis(indenes). Hydrosilylation with a chiral silane, (+)‐(R)‐methyl‐1‐naphthalenylphenylsilane, provides access to new chirally substituted indenes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Matching of uncalibrated stereo images by elastic deformation
Authors: Li Wan‐Chiu , Leung C. H. , Hung Y. S.
Published: March 2005

We propose a method for uncalibrated stereo matching. The method applies gradual elastic deformation to the line segments in a pair of images until they match with each other. By using an energy function and a neighborhood function, matching is performed in a coarse‐to‐fine manner. Our method gives point correspondences with a low proportion of outliers and is robust in the uncalibrated case (with no need to estimate the epipolar geometry). The computation complexity is proportional to the square of the number of line segments in the images, which is relatively efficient compared with other elaborate methods. © 2005 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 14, 198–205, 2004; Published online in Wiley Inter‐Science (www.interscience.wiley.com). DOI 10.1002/ima.20024
Ethane oxidation and pyrolysis from 5 bar to 1000 bar: Experiments and simulation
Authors: Tranter R. S. , Raman A. , Sivaramakrishnan R. , Brezinsky K.
Published: March 2005

An extensive experimental study of ethane oxidation and pyrolysis has been conducted in the high pressure shock tube at UIC covering reflected shock pressures from 5–1000 bar, reaction temperatures up to 1550 K and stoichiometric (Φ = 1), fuel rich (Φ = 5), and pyrolytic mixtures. The experimental data has been used to develop a single model that can simulate the whole dataset very well and is the first ethane model capable of simulating experimental results over such an extensive range of pressure, temperature, and stoichiometry. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 306–331, 2005
Public character: Philanthropic fundraising and the claims of accountability
Authors: Pribbenow Paul
Published: March 2005

This chapter gives advice for fundraisers on responding to the pressures of a changing environment and focusing on the publics fundraisers serve.
Ferroelectric properties of Sm‐doped Bi4Ti3O12 thin films
Authors: Chen M. , Liu Z. L. , Wang Y. , Yao K. L.
Published: March 2005

Sm‐doped bismuth titanate and random oriented Bi4–xSmxTi3O12 (BST) thin films were fabricated on Pt/Ti/SiO2/Si substrates using a pulsed laser deposition method. The structures and the ferroelectric properties of the films were investigated. Sm doping leads to a marked improvement in the remanent polarization (Pr) and the coercive field (Ec). At an applied electric field of 100 kV/cm, Pr and Ec of a BST (x = 0.8) film annealed at 650 °C are 20.5 µC/cm2 and 60 kV/cm, respectively. However, after 3 × 1010 switching cycles, 20% degradation of 2Pr is observed in the film. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A vibrational analysis of the 7‐azaindole‐water complex: Anharmonicities using the quartic force field
Authors: Taketsugu Tetsuya , Yagi Kiyoshi , Gordon Mark S.
Published: March 2005

Vibrational frequencies for the 7‐azaindole and 7‐azaindole‐water complex are calculated by the vibrational self‐consistent field (VSCF) and correlation‐corrected VSCF (cc‐VSCF) methods using second‐order perturbation theory (MP2), with the 6‐31G(d) basis set, and density functional theory with the B3LYP functional and the same basis set. The potential energies at quadrature points for VSCF calculations are estimated from the quartic force field (QFF) determined by the respective electronic structure methods. The comparison with experimental fundamentals for 7‐azaindole indicates that MP2 gives better results for NH and CH stretching modes than B3LYP, while B3LYP gives better results for CC stretching and ring deforming modes. The vibrational modes for the 7‐azaindole‐water complex are discussed in terms of those of the isolated 7‐azaindole and water. This VSCF/QFF approach will help quantitative evaluations of vibrational energies of a general polyatomic molecule with a reasonable computational cost. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
A Review of Obturator Hernia and a Proposed Algorithm for its Diagnosis and Treatment
Authors: Chang Shen‐Shin , Shan Yan‐Shen , Lin Yih‐Jyh , Tai Yun‐Sheng , Lin Pin‐Wen
Published: March 2005

The aim of this article is to provide a review of six patients with the various stages of obturator hernia and a diagnostic and therapeutic strategy in suspected cases. Obturator hernia is relatively rare and is a diagnostic challenge. It is a significant cause of intestinal obstruction, especially in emaciated elderly women with chronic disease. A palpable groin mass is not common in these patients because the hernia mass is usually concealed beneath the pectineus muscle. The high mortality is directly related to the delayed recognition, with resultant ruptured gangrenous bowel, and to the high incidence of patients with concurrent medical illness. A total of six patients with obturator hernias were treated at this hospital between 1994 and 2004, and one of these patients was diagnosed and treated by elective laparoscopy. We reviewed these six cases and examined the clinical presentation, age, body weight, associated medical conditions, preoperative diagnosis, operative findings, complications, and outcome in this retrospective study. We concluded that we cannot shorten the time from onset of symptoms to admission, but what we can do is to make a rapid evaluation and surgical intervention to reduce the morbidity and mortality from obturator hernia. The approaches to different presentation of obturator hernia and diagnostic role of CT scan are also discussed.
Biomechanical and allergological characteristics of a biodegradable poly(D,L‐lactic acid) coating for orthopaedic implants
Authors: Gollwitzer Hans , Thomas Peter , Diehl Peter , Steinhauser Erwin , Summer Burkard , Barnstorf Sonja , Gerdesmeyer Ludger , Mittelmeier Wolfram , Stemberger Axel
Published: March 2005

A poly(D,L‐lactic acid) surface coating (PDLLA) has been developed to optimize interactions at the implant‐tissue interface. Mechanical and allergological characteristics were evaluated in the present study to elucidate possible indications and limitations prior to clinical application. Implants of stainless steel and Ti–6Al–4V and CoCrMo alloys were coated with PDLLA, and mechanical stability was studied during intramedullary implantation into rat and human cadaver bones and during dilation of coronary artery stents. Elongation resistance was examined on AlMgSi alloy specimens. Furthermore, proliferation of peripheral blood mononuclear cells of nickel‐allergic donors and controls and interleukin‐4 and interferon‐γ levels were measured in the presence of coated/uncoated implants and after stimulation with phytohemagglutinin or NiSO4. PDLLA remained stable on the implants with a minimum of 96% of the original coating mass and tolerated lengthening of at least 8%. Further lengthening was followed by microcracking and cohesive failure within the coating. PDLLA exerted no suppressive effect upon spontaneous and pan‐T‐cell mitogen inducible T‐cell proliferation. Furthermore, specific proliferation to nickel in cells of nickel‐allergic blood donors and production of interleukin‐4 and IFN‐γ were not influenced by the coating. PDLLA coating proved high mechanical stability on different orthopaedic implants and did not influence in vitro T‐cell reactivity towards specific biomaterials. © 2005 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
Theoretical Evaluation of Capillary Electrophoresis Performance
Authors: Datta Ravindra
Published: March 2005

An analytical model (Datta and Kotamarthi, 1990) for the electrokinetic dispersion coefficient in capillary electrophoresis (CE), for the case of low ν‐potential, that accounts for the effects of pressure‐driven and/or electroosmotic flow of the elutant, is utilized here to theoretically explore the performance of CE in terms of plate height, plate number, peak resolution, resolving power, and the time of analysis. Practical operating conditions for the voltage gradient and Poiseuille flow fraction, v, are explored that optimize CE column performance. The implications of the results in the rational design of CE columns are discussed. It is also shown that the superposition of Poiseuille flow on the natural electroosmotic flow, while allowing greater freedom in the choice of elutant velocity, does not always cause increased dispersion.
Slit Scanning of Saccharomyces cerevisiae Cells: Quantification of Asymmetric Cell Division and Cell Cycle Progression in Asynchronous Culture
Authors: Block David E. , Eitzman Philip D. , Wangensteen Jeffrey D. , Srienc Friedrich
Published: March 2005

Slit scanning flow cytometry has been applied to the analysis of the cell cycle and cellcycle‐dependent events in Saccharomyces cerevisiae, yielding information on the low‐resolution spatial distribution of cellular components in single cells of unperturbed cell populations. Because this process is rapid, large numbers of cells can be analyzed to give distributions of parameters in a given population. To study asymmetric cell division and cell cycle progression, forward‐angle light scattering (FALS) signals together with fluorescence signals from acriflavine‐stained nuclei have been measured in cells from exponentially growing yeast populations. An algorithm has been developed that assigns the position of the bud neck in the FALS signals so that both FALS and DNA signals can be analyzed in terms of the contributions from the mother cell and the cell bud. The data indicate that mother cell FALS, on average, remains constant while FALS due to the cell bud increases as a cell progresses through the cell cycle. By identifying mitotic cells and measuring their properties, we have found that the coefficient of variation for the distribution of FALS is smallest within the dividing cell population and largest within the newborn cell population, in accordance with the critical size control mechanism of yeast cell growth. The use of this experimental approach to provide data for statistical population models is discussed.