bluuebunny/crossref_metadata_2025 huggingface dataset:
Short Gamma-ray bursts: a bimodal origin?
Authors: Salvaterra R. , Cerutti A. , Chincarini G. , Colpi M. , Guidorzi C. , Romano P.
Published: May 2008

Short-hard Gamma-Ray Bursts (SGRBs) are currently thought to arise from gravitational wave driven coalescences of double neutron star systems forming either in the field or dynamically in globular clusters. For both channels, we fit the peak flux distribution of BATSE SGRBs to derive the local burst formation rate and luminosity function. We then compare the resulting redshift distribution with Swift 2-yr data, showing that both formation channels are needed in order to reproduce the observations. Double neutron stars forming in globular clusters are found to dominate the distribution at z≲ 0.3, whereas the field population from primordial binaries can account for the high-z SGRBs. This result is not in contradiction with the observed host galaxy type of SGRBs.
EFFECT OF PROCESSING CONDITIONS ON INSTRUMENTAL EVALUATION OF NIXTAMAL HARDNESS OF CORN
Authors: IBARRA‐MENDÍVIL M.H. , GALLARDO‐NAVARRO Y.T. , TORRES P.I. , RAMÍREZ WONG B.
Published: May 2008

Two varieties of corn (Blanco and Toluca) were cooked in water at boiling temperature (at a ratio of 1:3) for different cooking times (25 or 45 min) and concentrations of lime (0.0, 0.5 or 1.0%). The cooked corn was allowed to rest for 5 or 14 h, resulting in the nixtamal product. The nixtamal was tested for hardness utilizing the nixtamal puncture cell (NPC) connected to a texturometer. The parameters of hardness measured were the maximum force (MF) required to rupture the nixtamal and the modulus of elasticity (ME). It also were determined the moisture content of the nixtamal, pH of the nejayote and loss of solids into the nejayote. The concentration of lime, cooking time and corn variety had a highly significant effect (P < 0.01) on the MF and ME of the nixtamal. Both determinations correlated very significantly with the moisture content of the nixtamal (r = −0.94 and r = −0.96, respectively). The ME values correlated significantly (P < 0.05) with the loss of solids and pH of the nejayote (r = −0.881 and r = −0.858, respectively). The NPC was capable of detecting the difference in the hardness of nixtamal obtained under different conditions of the traditional nixtamalization process, where it could be a useful tool for further studies of this raw material in the production of corn tortillas.

PRACTICAL APPLICATIONS

Nixtamal is the alkaline cooked corn in the process to make corn tortillas. Actually, nixtamal hardness evaluation is made subjectively by the operator of the process. Depending on the nixtamal texture are the masa and the tortilla texture. Therefore, with the nixtamal punch cell, nixtamal hardness can be measured instrumentally and a better control of the corn tortilla process could be carry out. In addition, with the nixtamal puncture cell it is possible to study any factor affecting the nixtamal hardness.
EFFECT OF PACIFIC WHITING WASH WATER PROTEINS ON ALASKA POLLACK SURIMI GELS
Authors: VELAZQUEZ GONZALO , MIRANDA‐LUNA PATRICIA , LÓPEZ‐ECHEVARRÍA GERARDO , VÁZQUEZ MANUEL , TORRES J. ANTONIO , RAMÍREZ JOSÉ A.
Published: May 2008

The objective of this work was to evaluate the effect of adding insoluble proteins recovered from Pacific whiting surimi wash water (SWW) on the mechanical and functional properties of Alaska pollack surimi gels. Insoluble proteins from Pacific whiting SWW were added at 0 (control), 10, 30 or 50 g/kg into Alaska pollack grade FA surimi. Changes on mechanical properties, expressible water (EW) and color attributes were evaluated in pastes and gels. Results obtained showed that texture profile analysis, puncture test and EW parameters increased significantly by increasing the amount of insoluble proteins added. Although slight changes in color attributes were detected, all surimi gels remained in the same color zone. The results obtained suggest that insoluble proteins from Pacific whiting SWW could be used to improve the mechanical properties of Alaska pollack grade FA surimi gels with a minimum effect on color.

PRACTICAL APPLICATIONS

Insoluble proteins recovered from surimi wash water (SWW) of Pacific whiting added at 10–50 g/kg to Alaska pollack surimi showed no adverse effects on their textural properties (hardness, fracturability, springiness and chewiness) and slight changes on color attributes. The results obtained suggest that it is feasible the use of insoluble proteins recovered from SWW of Pacific whiting in Alaska pollack surimi. Therefore, a double target is obtained: the preservation of environment and an increase in the yield of surimi processing without negative effects on texture.
“Chocolate City” Politics: Race and Empowerment in the First Post‐Katrina New Orleans Mayoral Election
Authors: McBride Allan , Parker Joseph B.
Published: May 2008

The first New Orleans mayor's election after Hurricane Katrina took place in May of 2006. The setting for the election is perhaps unique in American history: the total evacuation of the city after the hurricane with less than half of its citizens returning by the time of the election, possibly as much as 60‐80 percent of the city destroyed, and the African‐American community in danger of losing its hold on the city's formal power structure. As a black empowerment zone, the city has had a series of black mayors since the 1970s. In early 2006 the demographics of the city remained uncertain. Although the hurricane loomed as the single largest issue in the election, race was the subtext. Analysis of precinct voting data points to the significance of race and empowerment in the final results.
“None of the Above?” Casting Blank Ballots in Ontario Provincial Elections
Authors: Galatas Steven
Published: May 2008

Are blank or unmarked ballots in an election a random event? The comparative literature on elections suggests otherwise, linking blank ballots to political protest or social and demographic characteristics of voters. Rational choice theory offers explanations rooted in civic duty and net benefits associated with uncompetitive elections. Similarly, when a voter decides to vote, the literature on party competition and electoral turnout offers the possibility that a blank ballot is another choice beyond voting for a specific candidate or party. While little research exists on blank ballots in election systems lacking compulsory voting, this article presents an exploratory analysis using data from the 1999 and 2003 provincial elections in Ontario. The study finds that while demographic characteristics matter, party competition also provides an explanation for casting blank ballots consistent with expectations of rational choice theory.
The Cartel Party and the Italian Case1
Authors: Pelizzo Riccardo
Published: May 2008

Cartel party literature has generated three lines of research investigating the transformation of party organizations, the party system, and policy output. The third line of research, which could be defined as the political economy of the cartel party, has shown that party systems resemble oligopolistic markets in two respects: the policy output has changed and voters have the impression that changes in political supply did not represent adjustments to the transformation of voters' demands. Yet literature on this subject has not provided any evidence to sustain the claim that parties' behavior resembles the behavior of oligopolistic firms in a cartel. The purpose of the present article is to show that the legislative behavior of Italian parties gives the impression that Italian parties are engaged in collusive practices and that, for this reason, it is appropriate to regard the Italian party system not only as oligopolistic but also as a cartel.
The Cat and Mouse Game at the Mexico-U.S. Border: Gendered Patterns and Recent Shifts
Authors: Donato Katharine M. , Wagner Brandon , Patterson Evelyn
Published: May 2008

This paper provides new insights into the process of undocumented border crossing by examining both men and women in the process. We investigate differences in the ways in which men and women make their way across the well-guarded Mexico-U.S. border, and the extent to which men and women by the end of the 1990s were similar to, or different from, their counterparts who crossed before 1986 and the implementation of immigration policy designed to reduce undocumented migration. We find substantial differences in how men and women crossed the border without legal documents and in their chances of being apprehended. Our analysis makes clear that shifts in U.S. immigration policy after 1986 have led to women's greater reliance on the assistance of paid smugglers to cross without documents but men were more likely to cross alone. Moreover, immediately after 1986, women on first U.S. trips faced higher risks of being apprehended compared to women who migrated in the early 1980s, but men faced lower risks. After accumulating some U.S. experience, however, both women and men faced lower risks of being detected after 1986 compared to earlier in that decade.
Immigrant Religion in the U.S. and Western Europe: Bridge or Barrier to Inclusion?
Authors: Foner Nancy , Alba Richard
Published: May 2008

This article analyzes why immigrant religion is viewed as a problematic area in Western Europe in contrast to the United States, where it is seen as facilitating the adaptation process. The difference, it is argued, is anchored in whether or not religion can play a major role for immigrants and the second generation as a bridge to inclusion in the new society. Three factors are critical: the religious backgrounds of immigrants in Western Europe and the United States; the religiosity of the native population; and historically rooted relations and arrangements between the state and religious groups.
Toward a Demography of Immigrant Communities and Their Transnational Potential
Authors: Carling Jørgen
Published: May 2008

This article lays out a foundation for a demographic perspective on the development of immigrant communities. Such a perspective can strengthen the connections between in-depth ethnographic analysis and macro-level trends. New applications of the so-called Lexis diagram are introduced in order to relate the current composition of immigrant communities to past immigration policy and migration patterns. The article also explores relationships between the demographic structure of immigrant populations and their transnational orientation. The analyses are demonstrated empirically through a case study of migration from Cape Verde to the Netherlands.
The Ancestry Question and Ethnic Heterogeneity: The Case of Arab Americans
Authors: Dallo Florence J. , Ajrouch Kristine J. , Al-Snih Soham
Published: May 2008

This article uses US Census data to investigate change over time in Arab American profiles. In 2000, a higher proportion of children (0 to 13 years of age), women, and those who lived in the Northeast identified with an Arab/non-Arab ancestry compared to an Arab-only ancestry. In 1980 and 2000, a higher proportion (~90%) of those who identified with an Arab/non-Arab ancestry was US born compared to only one-half of those who identified with an Arab-only ancestry. Those who identified with an Arab-only ancestry were more likely to not be US citizens than those who identified with an Arab/non-Arab ancestry. These findings suggest Arab Americans are a heterogeneous group.
Kadhi Court and Appointment of Kadhi in Kenya Colony
Authors: Mwakimako Hassan
Published: May 2008

Prior to 1895 when European legal institutions became dominant among Muslim communities in Kenya, ulama were prominent men of religion whose authority depended as much on their religious standing and moral authority. Ulama played significant socio‐political and religious roles. However, colonial rule introduced structured justice and a court system that changed the way ulama operated. Their authority now rested on their legal expertise, colonial patronage and prestige of office. This inter play is discussed through a review of the appointment of Sharif Umar b. Abd Allah al Mahdaly to be Kadhi of Mumias in western Kenya during the Colonial Era.
Scripture as Guru in the Sikh Tradition
Authors: Singh Pashaura
Published: May 2008

The study of the Sikh scripture, the Adi Granth, is quite useful in understanding the general notion of ‘scripture’ as a cross‐cultural phenomenon. In fact, the study of a text as scripture is not only concerned with its textual problems, the reconstruction of its history, the formation of the canon, and its contextual meaning, but also with its ongoing role in the cumulative tradition of a religious community, both as a normative source of authority and as a prodigious living force. Perceived from this angle the reception of the Adi Granth as Guru by the Sikh community is highly significant.
Activity‐Regulated Cytoskeleton‐Associated Protein in Rodent Brain is Down‐Regulated by High Fat Diet in vivo and by 27‐Hydroxycholesterol in vitro
Authors: Mateos Laura , Akterin Susanne , Gil‐Bea Francisco‐Javier , Spulber Stefan , Rahman Atiqur , Björkhem Ingemar , Schultzberg Marianne , Flores‐Morales Amilcar , Cedazo‐Mínguez Angel
Published: May 2008

Growing evidence strongly suggests that high fat diet (HFD) has an important role in some neurodegenerative disorders, including Alzheimer's disease (AD). To identify new cellular pathways linking hypercholesterolemia and neurodegeneration, we analyzed the effects of HFD on gene expression in mouse brain. Using cDNA microarrays and real time RT‐PCR, we found that HFD has a mild, but significant effect on the expression of several genes. The altered genes include molecules linked to AD pathology and others of potential interest for neurodegeneration. We further investigated the effect of HFD on the activity‐regulated cytoskeleton‐associated protein (Arc). Expression of Arc was decreased in cerebral cortex and hippocampus of HFD‐fed animals. From the known regulatory mechanisms of Arc expression, HFD reduced N‐methyl‐D‐aspartate receptor (NMDAR) activity, as seen by decreases in tyrosine phosphorylation of NMDAR2A and levels of NMDAR1. Additionally, we demonstrated that 27‐hydroxycholesterol, a cholesterol metabolite that enters the brain from the blood, decreases Arc levels as well as NMDAR and Src kinase activities in rat primary hippocampal neurons. Finally, we showed that Arc levels are decreased in the cortex of AD brains. We propose that one of the mechanisms, by which hypercholesterolemia contributes to neurodegenerative diseases, could be through Arc down‐regulation caused by 27‐hydroxycholesterol.
Permethrin toxicity in cats: a retrospective study of 20 cases
Authors: DYMOND NL , SWIFT IM
Published: May 2008

Objective Permethrin is a synthetic pyrethroid widely used in flea control products for small animals. Accidental toxicity can occur with off‐label usage, and cats are particularly susceptible.

Methods Retrospective study of 20 cases of permethrin toxicity in cats treated at an emergency clinic in Brisbane, Queensland from October 2004 to June 2005.

Results The diagnosis of permethrin toxicity was made on the basis of a history of exposure and characteristic clinical signs, including seizures, muscle fasciculations, and tremors. Decontamination and appropriate seizure or muscle fasciculation control were the basis of treatment. The outcome was good after rapid intervention and 19 of the 20 cats were successfully treated, with the only death occurring in a kitten for which treatment was delayed for 24 h. No long‐term complications were reported by the cats’ owners at 4‐month follow‐up after discharge from hospital.

Conclusions Owner education, together with more appropriate product labelling, may help eliminate this problem in the future.
To catch a buffalo: field immobilisation of Asian swamp buffalo using etorphine and xylazine
Authors: MCMAHON CR , BRADSHAW CJA
Published: May 2008

Objective  To demonstrate the efficacy of a mixture of etorphine and xylazine to safely immobilise wild buffalo (Bubalus bubalis) in the field.

Methods  Body mass was estimated (to calculate mass‐specific dosages) by deriving a predictive relationship between morphometric measurements (body length, height) and mass based on a dataset collected in Vietnam, because the study animals could not be weighed in the field.

Results  Mass‐specific dosages varied between 0.02 and 0.03 mg/kg for etorphine and between 0.14 and 0.22 mg/kg for xyalazine; induction times varied between 10 and 33 min, mean recumbency time was 68 min, and the mean time to standing was 10 min (range: 10–17 min).

Conclusions  The mixture of ethorphine and xylazine was effective for immobilisation of this species and appeared to have a relatively large safety margin, based on the mass‐specific dosages used. The allometric relationships described here should prove useful for those working with wild swamp buffalo.
Psychosocial Perspectives on Pregnancy: Prenatal Maternal Stress and Coping
Authors: Lobel Marci , Hamilton Jada G. , Cannella Dolores T.
Published: May 2008

Pregnancy is a momentous life event experienced by most women that involves biomedical and psychosocial changes that are potentially stressful. High levels of maternal stress in pregnancy contribute to adverse fetal, infant, child, and adult outcomes, including cognitive, emotional, neurodevelopmental, and physical health effects. This article discusses definition, measurement, and effects of stress in pregnancy and describes current research questions such as whether the timing or pattern of prenatal stress accentuates its effects and whether prenatal stress accounts for ethnic disparities in adverse birth outcomes in the United States. We review research on the ways that women cope with prenatal stress and research examining associations of coping with maternal emotional state, health, and birth outcomes. Additionally, we describe important factors that improve women's psychosocial adaptation to pregnancy, their health, and their birth outcomes, specifically trait optimism, social support, and physical activity, and we emphasize interventions that utilize these factors.
Moving Toward a Secure Attachment Style: Can Repeated Security Priming Help?
Authors: Gillath Omri , Selcuk Emre , Shaver Phillip R.
Published: May 2008

Despite the abundant literature on attachment processes and the development of a secure or insecure attachment orientation during childhood, it is still unclear whether adult attachment style can be changed through systematic interventions, and if so how the change process works. One way to learn more about such change is to create it, on a small scale, in the laboratory. It is already known that a person's sense of security can be momentarily changed in the laboratory (Mikulincer & Shaver, 2007a). But there is clearly a difference between very short‐term and longer‐term change. According to Bowlby (1982), the development of an attachment orientation in childhood is based on many encounters and interactions with caregivers, which gradually create a mental network of relatively stable expectations and concerns. Thus, it may take many episodes of security priming in a laboratory to begin to affect a young adult's attachment style in a lasting way. Here, we explore this possibility, review existing evidence from our own and other researchers’ laboratories, and discuss directions for future research.
Evaluating a conservation investment designed to reduce human–wildlife conflict
Authors: Gore Meredith L. , Knuth Barbara A. , Scherer Clifford W. , Curtis Paul D.
Published: May 2008

Outreach programs are interventions that have the potential to influence the unique context of human–wildlife conflict as well as the political, economic, and social systems within which human–wildlife conflict occurs. However, evaluation of these programs is limited. The purpose of this research was to determine a human–wildlife conflict outreach intervention's effect on environmentally responsible behavior using the case of human–black bear conflict in New York, The New York NeighBEARhood Watch Program, and the Elaboration Likelihood Model. We found no short‐term evidence of environmentally responsible behavior change after the program was implemented. We discuss inhibitors of desired program impact and the utility of our evaluation framework to measure program effect. Given the staying power of outreach interventions and their unknown effects on mitigating human–wildlife conflict, it is imperative that evaluation of programs be a required part of their implementation. Results presented herein can advance discussion about the role of outreach interventions by highlighting assumptions, realistic expectations, and outcome measures.
Implant radiography and radiology
Authors: Monsour PA , Dudhia R
Published: May 2008

The practitioner placing dental implants has many options with respect to pre‐implant radiographic assessment of the jaws. The advantages and disadvantages of the imaging modalities currently available for pre‐implant imaging are discussed in some detail. Intra‐oral and extra‐oral radiographs are generally low dose but the information provided is limited as the images are not three‐dimensional. Tomography is three‐dimensional, but the image quality is highly variable. Computed tomography (CT) has been the gold standard for many years as the information provided is three‐dimensional and generally very accurate. However, CT examinations are expensive and deliver a relatively high radiation dose to the patient. The latest imaging modality introduced is cone beam volumetric tomography (CBVT) and this technology is very promising with regard to pre‐implant imaging. CBVT generally delivers a lower dose to the patient than CT and provides reasonably sharp images with three‐dimensional information. A comparison between CT and CBVT is provided. Magnetic resonance imaging is showing some promise, but the examinations are not readily available, generally expensive and bone is not well imaged. Magnetic resonance imaging is excellent for demonstrating soft tissues and therefore may be of great use in identifying the inferior dental nerve and vessels. All of the above technology is of little value if the information required is not obtained and so information is also provided on imaging of some of the vital structures. Of particular interest is the inferior dental canal, incisive canals of the mandible, genial foramina and canals, maxillary sinus and the incisive canal and foramen of the maxilla.
Occlusion in implant dentistry. A review of the literature of prosthetic determinants and current concepts
Authors: Gross MD
Published: May 2008

Today the clinician is faced with widely varying concepts regarding the number, location, distribution and inclination of implants required to support the functional and parafunctional demands of occlusal loading. Primary clinical dilemmas of planning for maximal or minimal numbers of implants, their axial inclination, lengths and required volume and quality of supporting bone remain largely unanswered by adequate clinical outcome research. Planning and executing optimal occlusion schemes is an integral part of implant supported restorations. In its wider sense this includes considerations of multiple inter‐relating factors of ensuring adequate bone support, implant location number, length, distribution and inclination, splinting, vertical dimension aesthetics, static and dynamic occlusal schemes and more.

Current concepts and research on occlusal loading and overloading are reviewed together with clinical outcome and biomechanical studies and their clinical relevance discussed. A comparison between teeth and implants regarding their proprioceptive properties and mechanisms of supporting functional and parafunctional loading is made and clinical applications made regarding current concepts in restoring the partially edentulous dentition. The relevance of occlusal traumatism and fatigue microdamage alone or in combination with periodontal or peri‐implant inflammation is reviewed and applied to clinical considerations regarding splinting of adjacent implants and teeth, posterior support and eccentric guidance schemes.

Occlusal restoration of the natural dentition has classically been divided into considerations of planning for sufficient posterior support, occlusal vertical dimension and eccentric guidance to provide comfort and aesthetics. Mutual protection and anterior disclusion have come to be considered as acceptable therapeutic modalities. These concepts have been transferred to the restoration of implant‐supported restoration largely by default. However, in light of differences in the supporting mechanisms of implants and teeth many questions remain unanswered regarding the suitability of these modalities for implant supported restorations. These will be discussed and an attempt made to provide some current clinical axioms based where possible on the best available evidence.
Immediate loading of dental implants
Authors: Henry PJ , Liddelow GJ
Published: May 2008

The purpose of this review is to explore the concept of immediate loading as it pertains to dental implants and the indications for clinical practice. The definition of immediate loading will be considered together with a review of the relevant literature in an attempt to provide evidence‐based guidelines for successful implementation into practice.

A search of electronic databases including Medline, PubMed and the Cochrane Database of Systematic Reviews was undertaken using the terms ``immediate loading'', ``dental implants'', ``immediate function'', ``early loading'', ``oral implants'', ``immediate restoration'' and ``systematic review''. This was supplemented by handsearching in peer‐reviewed journals and cross‐referenced with the articles accessed. Emphasis was given to systematic reviews and controlled clinical trials.

A definition of immediate loading was suggested pertinent to the realities of logistics in clinical practice with respect to application and time frame. The literature was evaluated and shown to be limited with significant shortcomings. Guidelines and recommendations for clinical protocols were suggested and illustrated by examples of case types with a minimum of 1–3 years follow‐up. A list of additional references for further reading was provided.

Within the limitations of this review, there is evidence to suggest that immediate loading protocols have demonstrated high implant survival rates and may be cautiously recommended for certain clinical situations. However, more high level evidence studies, preferably randomized controlled trials (RCTs), over a long time frame are required to show a clear benefit over more conventional loading protocols.
Relative contributions of TRPA1 and TRPV1 channels in the activation of vagal bronchopulmonary C‐fibres by the endogenous autacoid 4‐oxononenal
Authors: Taylor‐Clark T. E. , McAlexander M. A. , Nassenstein C. , Sheardown S. A. , Wilson S. , Thornton J. , Carr M. J. , Undem B. J.
Published: May 2008

Transient receptor potential (TRP) A1 channels are cation channels found preferentially on nociceptive sensory neurones, including capsaicin‐sensitive TRPV1‐expressing vagal bronchopulmonary C‐fibres, and are activated by electrophilic compounds such as mustard oil and cinnamaldehyde. Oxidative stress, a pathological feature of many respiratory diseases, causes the endogenous formation of a number of reactive electrophilic alkenals via lipid peroxidation. One such alkenal, 4‐hydroxynonenal (4HNE), activates TRPA1 in cultured sensory neurones. However, our data demonstrate that 100 μm 4HNE was unable to evoke significant action potential discharge or tachykinin release from bronchopulmonary C‐fibre terminals. Instead, another endogenously produced alkenal, 4‐oxononenal (4ONE, 10 μm), which is far more electrophilic than 4HNE, caused substantial action potential discharge and tachykinin release from bronchopulmonary C‐fibre terminals. The activation of mouse bronchopulmonary C‐fibre terminals by 4ONE (10–100 μm) was mediated entirely by TRPA1 channels, based on the absence of responses in C‐fibre terminals from TRPA1 knockout mice. Interestingly, although the robust increases in calcium caused by 4ONE (0.1–10 μm) in dissociated vagal neurones were essentially abolished in TRPA1 knockout mice, at 100 μm 4ONE caused a large TRPV1‐dependent response. Furthermore, 4ONE (100 μm) was shown to activate TRPV1 channel‐expressing HEK cells. In conclusion, the data support the hypothesis that 4‐ONE is a relevant endogenous activator of vagal C‐fibres via an interaction with TRPA1, and at less relevant concentrations, it may activate nerves via TRPV1.
Differential dissociation of G protein heterotrimers
Authors: Digby Gregory J. , Sethi Pooja R. , Lambert Nevin A.
Published: May 2008

Signalling by heterotrimeric G proteins is often isoform‐specific, meaning certain effectors are regulated exclusively by one family of heterotrimers. For example, in excitable cells inwardly rectifying potassium (GIRK) channels are activated by Gβγ dimers derived specifically from Gi/o heterotrimers. Since all active heterotrimers are thought to dissociate and release free Gβγ dimers, it is unclear why these channels respond primarily to dimers released by Gi/o heterotrimers. We reconstituted GIRK channel activation in cells where we could quantify heterotrimer expression at the plasma membrane, GIRK channel activation, and heterotrimer dissociation. We find that GoA heterotrimers are more effective activators of GIRK channels than Gs heterotrimers when comparable amounts of each are available. We also find that active GoA heterotrimers dissociate more readily than active Gs heterotrimers. Differential dissociation may thus provide a simple explanation for Gα‐specific activation of GIRK channels and other Gβγ‐sensitive effectors.
Synaptic integration and plasticity of new neurons in the adult hippocampus
Authors: Ge Shaoyu , Sailor Kurt A. , Ming Guo‐li , Song Hongjun
Published: May 2008

Adult neurogenesis, a developmental process encompassing the birth of new neurons from adult neural stem cells and their integration into the existing neuronal circuitry, highlights the plasticity and regenerative capacity of the adult mammalian brain. Substantial evidence suggests essential roles of newborn neurons in specific brain functions; yet it remains unclear how these new neurons make their unique contribution. Recently, a series of studies have delineated the basic steps of the adult neurogenesis process and shown that many of the distinct steps are dynamically regulated by the activity of the existing circuitry. Here we review recent findings on the synaptic integration and plasticity of newborn neurons in the adult hippocampus, including the basic biological process, unique characteristics, critical periods, and activity‐dependent regulation by the neurotransmitters GABA and glutamate. We propose that adult neurogenesis represents not merely a replacement mechanism for lost neurons, but also an ongoing developmental process in the adult brain that offers an expanded capacity for plasticity for shaping the existing circuitry in response to experience throughout life.
Evidence for Upwelling of Corrosive "Acidified" Water onto the Continental Shelf
Authors: Feely Richard A. , Sabine Christopher L. , Hernandez-Ayon J. Martin , Ianson Debby , Hales Burke
Published: May 2008

The absorption of atmospheric carbon dioxide (CO
2
) into the ocean lowers the pH of the waters. This so-called ocean acidification could have important consequences for marine ecosystems. To better understand the extent of this ocean acidification in coastal waters, we conducted hydrographic surveys along the continental shelf of western North America from central Canada to northern Mexico. We observed seawater that is undersaturated with respect to aragonite upwelling onto large portions of the continental shelf, reaching depths of ∼40 to 120 meters along most transect lines and all the way to the surface on one transect off northern California. Although seasonal upwelling of the undersaturated waters onto the shelf is a natural phenomenon in this region, the ocean uptake of anthropogenic CO
2
has increased the areal extent of the affected area.
Evolution of Mammals and Their Gut Microbes
Authors: Ley Ruth E. , Hamady Micah , Lozupone Catherine , Turnbaugh Peter J. , Ramey Rob Roy , Bircher J. Stephen , Schlegel Michael L. , Tucker Tammy A. , Schrenzel Mark D. , Knight Rob , Gordon Jeffrey I.
Published: May 2008

Mammals are metagenomic in that they are composed of not only their own gene complements but also those of all of their associated microbes. To understand the coevolution of the mammals and their indigenous microbial communities, we conducted a network-based analysis of bacterial 16
S
ribosomal RNA gene sequences from the fecal microbiota of humans and 59 other mammalian species living in two zoos and in the wild. The results indicate that host diet and phylogeny both influence bacterial diversity, which increases from carnivory to omnivory to herbivory; that bacterial communities codiversified with their hosts; and that the gut microbiota of humans living a modern life-style is typical of omnivorous primates.
The Rag GTPases Bind Raptor and Mediate Amino Acid Signaling to mTORC1
Authors: Sancak Yasemin , Peterson Timothy R. , Shaul Yoav D. , Lindquist Robert A. , Thoreen Carson C. , Bar-Peled Liron , Sabatini David M.
Published: May 2008

The multiprotein mTORC1 protein kinase complex is the central component of a pathway that promotes growth in response to insulin, energy levels, and amino acids and is deregulated in common cancers. We find that the Rag proteins—a family of four related small guanosine triphosphatases (GTPases)—interact with mTORC1 in an amino acid–sensitive manner and are necessary for the activation of the mTORC1 pathway by amino acids. A Rag mutant that is constitutively bound to guanosine triphosphate interacted strongly with mTORC1, and its expression within cells made the mTORC1 pathway resistant to amino acid deprivation. Conversely, expression of a guanosine diphosphate–bound Rag mutant prevented stimulation of mTORC1 by amino acids. The Rag proteins do not directly stimulate the kinase activity of mTORC1, but, like amino acids, promote the intracellular localization of mTOR to a compartment that also contains its activator Rheb.
β-Arrestin–Mediated Localization of Smoothened to the Primary Cilium
Authors: Kovacs Jeffrey J. , Whalen Erin J. , Liu Renshui , Xiao Kunhong , Kim Jihee , Chen Minyong , Wang Jiangbo , Chen Wei , Lefkowitz Robert J.
Published: May 2008

β-Arrestins have important roles in the regulation of seven-transmembrane receptors (7TMRs). Smoothened (Smo) is a 7TMR that mediates effects of Hedgehog on developmental processes and whose dysregulation may cause tumorigenesis. β-Arrestins are required for endocytosis of Smo and signaling to Gli transcription factors. In mammalian cells, Smo-dependent signaling requires translocation to primary cilia. We demonstrated that β-arrestins mediate the activity-dependent interaction of Smo and the kinesin motor protein Kif3A. This multimeric complex localized to primary cilia and was disrupted in cells transfected with β-arrestin small interfering RNA. β-Arrestin 1 or β-arrestin 2 depletion prevented the localization of Smo to primary cilia and the Smo-dependent activation of Gli. These results suggest roles for β-arrestins in mediating the intracellular transport of a 7TMR to its obligate subcellular location for signaling.
Patterns of exercise-related inflammatory response in sickle cell trait carriers
Authors: Tripette Julien , Connes Philippe , Hedreville Mona , Etienne-Julan Maryse , Marlin Laurent , Hue Olivier , Hardy-Dessources Marie-Dominique
Published: May 2008

Objective

To clarify whether sickle cell trait (SCT) carriers (SCT group) present a specific postexercise inflammatory response to repeated and strenuous exercise.

Design

The patterns of inflammatory markers in response to repeated heavy exercise were investigated in SCT carriers (SCT group: eight men, 20.0±0.7 years) and subjects with normal haemoglobin (CONT group: seven men, 20.6±0.7 years). The exercise consisted of three successive maximal ramp exercise tests, interspaced with 10 min of recovery, and accomplished at room temperature. Blood was sampled at rest (TR), at the end of each of the three tests (T1, T2, T3) and during the immediate (T1 h, T2 h) and late (T24 h, T48 h) recovery periods. Standard haematological parameters and plasma levels of cytokines (TNFα, IL-6) and adhesion molecules: soluble L- and P-selectins (sL-selectin, sP-selectin), soluble vascular cell adhesion molecule-1 (sVCAM-1), soluble intracellular adhesion molecule-1 (sICAM-1) were measured.

Results

In both groups, the three successive maximal exercise bouts prompted an inflammatory response (ie, white blood cells and IL-6 levels increased in response to exercise). sICAM-1 and sVCAM-1 levels did not change during or after exercise and presented no difference between groups. However, during exercise, sL-selectin and sP-selectin kinetics differed between groups: sL-selectin increased earlier in the SCT group than in the CONT group, and sP-selectin statistically increased only in the SCT group.

Conclusion

Although the data do not indicate an extended exercise inflammatory response in SCT carriers, a specific activation of the L- and P-selectins was observed. Further studies are needed to determine whether the selectins' changes are evidence of greater risk for SCT carriers during physical exercise in specific conditions or an indication of a protective mechanism mediated by the shedding process of adhesion molecules.
Predicting Recruitment Variation from Year Class Specific Vertebral Counts: An Analysis of the Potential and a Plan for Verification
Authors: Frank Kenneth T.
Published: May 2008

Recruitment prediction has been an elusive and seemingly unobtainable goal with no entirely satisfactory general approach yet available. I propose the use of meristic variation, traditionally applied to problems associated with stock discrimination studies, as a new method to predict recruitment variation. The approach is evaluated using literature data on year class strength (YCS) and year class specific average vertebral counts (VS), two apparently interrelated variables that are affected by environmental factors operating during the early life history. Three marine stocks at the southern limit of their species geographic range (Georges Bank haddock (Melanogrammus aeglefinus), North Sea Atlantic cod (Gadus morhua), and North Sea Atlantic herring (Clupea harengus hargenus)) and one stock at its northern limit (Pacific herring (Clupea harengus pallasi)) generally conformed to the prediction of a positive relationship between YCS and VS for southern stocks and a negative relationship for northern stocks. Exceptions to these patterns were found among stocks showing low temporal variability in recruitment or for stocks whose year class formation is not linked to environmental factors that establish the vertebral count of a year class. The approach adopted is consistent with the growing initiative of focusing on characteristics of the survivors of a population to provide insight into recruitment mechanisms.
Seasonal Habitat Selection and Preferences by Cutthroat Trout (Oncorhynchus clarki) in a Small Coastal Stream
Authors: Heggenes Jan , Northcote Thomas G. , Peter Armin
Published: May 2008

Habitat selection by cutthroat trout (Oncorhynchus clarki) larger than 9 cm total length was monitored during winter and summer. The trout had strong preferences for depths >25 cm and areas where instream and overhead cover exceeded 40% of the local surface area. The fish selected a variety of substrate sizes. Stream areas with mean water velocities <20 cm/s were preferred. Compared with previous studies, the trout used low-velocity areas more, and we suggest that this is due to less competitive interaction from other young salmonids. The trout used the larger pools (>20 m2) considerably less during winter than during summer. Otherwise, little seasonal variation in habitat use was found. A composite measure of water depth and cover appeared to be the most important of the measured environmental factors influencing habitat selection in the stream. The larger trout, which were presumably dominant, occupied the deepest pool areas. The trout selected spatial habitats in proportions significantly different from the available habitat, demonstrating strong habitat preferences. It is concluded that observations of habitat occupancy without considering habitat availability may give biased results.
Impact of Bleached Kraft Mill Effluent on Population Characteristics, Liver MFO Activity, and Serum Steroid Levels of a Lake Superior White Sucker (Catostomus commersoni) Population
Authors: Munkittrick K. R. , Portt C. B. , Kraak G. J. Van Der , Smith I. R. , Rokosh D. A.
Published: May 2008

White sucker (Catostomus commersoni) collected from a site receiving primary-treated bleached kraft mill effluent (BKME) were older and had a higher condition factor than fish at a reference site and grew more slowly than fish from three other areas of Lake Superior. The BKME-exposed fish also exhibited an increased age to maturity, smaller gonads, lower fecundity with age, an absence of secondary sex characteristics in males, and females failed to show an increase in egg size with age. Lower serum estradiol and testosterone concentrations and greater hepatic mixed-function oxidase (MFO) activity, as measured by conversion of diphenyloxazole and benzo[ajpyrene were also observed in the BKME-exposed fish. The level of MFO activity varied with season; differences could not be detected between sites during the spring spawning period, but were markedly elevated (up to ninefold) at the BKME site during the summer. The poorer performance of fish at the BKME site appears to be related to decreased levels of serum steroids and consequent abnormalities in reproductive development and carbohydrate metabolism, although the relationship of the changes in steroid levels with the increased hepatic enzyme activity remains to be established.
Abundance and Feeding of Medusae and their Potential Impact as Predators on Other Zooplankton in Bedford Basin (Nova Scotia, Canada) during Spring
Authors: Matsakis Sophie , Conover Robert J.
Published: May 2008

Only five hydromedusan species (Sarsia princeps, Euphysa tentaculata, Rathkea octopunctata, Cosmetira sp., and Aglantha digitale) and one scyphomedusan (Aurelia aurita) were found in the upper 30 m of Bedford Basin during spring 1988. Medusan carbon weight and that of total zooplankton varied reciprocally, suggesting significant population control by gelatinous predators. In March, when zooplankton concentration was low (5–9 mg C∙m−3) and medusan weight less than 1% of this total, daily ingestion by medusans did not exceed 10% of zooplankton carbon weight. In May, when mesozooplankton concentration was greater than 10 mg C∙m−3 and predators more abundant, their potential daily impact was at least 59%. From March to June, mean impact was 15.8%. During this period, as medusans increased and copepods decreased, the proportion of copepods consumed continued to increase, while the fraction of eggs consumed, primarily those of potential competitors such as ctenophores and chaetognaths, decreased. Predation between different taxa of medusans was also found. A population decrease in Rathkea octopunctata, the dominant spring hydromedusan, may have been attributable to predation by Aurelia aurita.
An Approach to Modeling Crustacean Egg-Bearing Fractions as a Function of Size and Season
Authors: Restrepo Victor R. , Watson Reg A.
Published: May 2008

We present an approach to the analysis of crustacean egg production ogives with emphasis on detecting seasonal trends. The relationship between the proportion of gravid females (by size) and season is a prerequisite to the estimation of egg production potentials of populations. The basic method consists of relating, for each sample, the proportion of berried females with their size through a three-parameter logistic function where the asymptote may be less than 1. We then provide guidance for detecting seasonal trends in the estimates of the parameters for the individual samples. This is accomplished by restricting the basic model such that some parameters are considered to be either fixed for all samples or as simple functions of time or environmental variables such as temperature. Parameter estimates are obtained via maximum likelihood methods, and comparisons between alternative models are presented graphically and using likelihood ratio tests. We illustrate the approach and its application with data for a tropical shrimp, Penaeus esculentus, from northern Australia.
Cycling of Phosphatase Hydrolyzable Phosphorus in Streams
Authors: Klotz R. L.
Published: May 2008

The phosphorus fraction made available to organisms by the action of alkaline phosphatase, here termed phosphatase hydrolyzable phosphorus (PHP), was studied in central New York State streams. Annual mean PHP concentrations were <2.0 μg P∙L−1 for each of the four streams studied and were low relative to concentrations for lentic systems from the literature. The PHP to soluble reactive phosphorus (SRP) ratio, a measure of the relative importance of PHP for aquatic organisms, was typically in the 0.09–1.00 range, indicating that PHP could supply a significant amount of P at certain locations. Laboratory sorption experiments with varying ionic strength solutions and with Ca2+ versus Na+ suggested that PHP was probably bound to sediments by a different mechanism than SRP, one probably mediated by the organic moiety. Fine-grained sediments higher in organic matter sorbed excess PHP from solution at a greater rate than coarse-grained sediments, but also released more into PHP-depleted solutions.
Predicting Fish Mercury Levels from Physical Characteristics of Boreal Reservoirs
Authors: Johnston Thomas A. , Bodaly R. A. , Mathias J. A.
Published: May 2008

Reservoir formation has often resulted in increased fish mercury levels. Predicting the potential for increase prior to impoundment would be useful in future environmental impact assessment.. We developed several linear models relating mercury burdens of northern pike (Esox lucius), walleye (Stizostedion vitreum), and lake whitefish (Coregonus clupeaformis) to physical characteristics of 21 lakes and reservoirs in the Churchill River diversion region of northern Manitoba. Ratios of flooded terrestrial area to water volume of the reservoir itself (within-lake effects) and of inflowing waters (upstream effects) were able to explain 76–84% of the variation in mean mercury burden. Upstream effects consistently accounted for more variation than within-lake effects. We tested these models using data from 18 Canadian lakes and reservoirs. Manitoba reservoirs generally fit the models well. The largest deviations of observed mercury levels from predicted mercury levels were for reservoirs of northern Quebec and Labrador We attribute this to differences in the relative contributions of within-lake effects and upstream effects between reservoirs of this region and those used to build the models. Future models should refine the relative contributions of these two components for individual reservoirs.