bluuebunny/crossref_metadata_2025 huggingface dataset:
The regulatory role of the NO/cGMP signal transduction cascade during larval attachment and metamorphosis of the barnacleBalanus (=Amphibalanus) amphitrite
Authors: Zhang Yu , He Li-Sheng , Zhang Gen , Xu Ying , Lee On-On , Matsumura Kiyotaka , Qian Pei-Yuan
Published: August 2012

The barnacle Balanus amphitrite is among the most dominant fouling species on intertidal rocky shores in tropical and subtropical areas and is thus a target organism in antifouling research. After being released from adults, the swimming nauplius undertakes six molting cycles and then transforms into a cyprid. Using paired antennules, a competent cyprid actively explores and selects a suitable substratum for attachment and metamorphosis (collectively known as settlement). This selection process involves the reception of exogenous signals and subsequent endogenous signal transduction. To investigate the involvement of nitric oxide (NO) and cyclic GMP (cGMP) during larval settlement of B. amphitrite, we examined the effects of an NO donor and an NO scavenger, two nitric oxide synthase (NOS) inhibitors, and a soluble guanylyl cyclase (sGC) inhibitor on settling cyprids. We found that the NO donor sodium nitroprusside (SNP) inhibited larval settlement (referring both attachment and metamorphosis in this paper hereafter) in a dose-dependent manner. In contrast, both NO scavenger 2-(-4-Carboxypheny)-4,4,5,5-tetramethylimidazolineoxyl-1-oxyl-3-oxide (Carboxy-PTIO) and NOS inhibitors aminoguanidine hemisulfate (AGH) and S-methylisothiourea sulfate (SMIS) significantly accelerated larval settlement. Suppression of the downstream GC activity by using a GC-selective inhibitor 1H-(1,2,4)oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) could also significantly accelerate the larval settlement. Interestingly, the settlement inhibition effects of SNP could be attenuated by ODQ at all concentrations tested. In the developmental expression profiling of NOS and sGC, the lowest expression of both genes was detected in the cyprid stage, a critical stage for the larval decision of attachment and metamorphosis. In sum, we concluded that NO regulates larval settlement via mediating down-stream cGMP signalling.
Serotonergic neuroepithelial cells of the skin in developing zebrafish: morphology, innervation and oxygen-sensitive properties
Authors: Coccimiglio Maria L. , Jonz Michael G.
Published: August 2012

In teleost fish, O2 chemoreceptors of the gills (neuroepithelial cells, NECs) initiate cardiorespiratory reflexes during hypoxia. In developing zebrafish, hyperventilatory and behavioural responses to hypoxia are observed before development of gill NECs, indicating that extrabranchial chemoreceptors mediate these responses in embryos. We have characterised a population of cells of the skin in developing zebrafish that resemble O2-chemoreceptive gill NECs. Skin NECs were identified by serotonin immunolabelling and were distributed over the entire skin surface. These cells contained synaptic vesicles and were associated with nerve fibres. Skin NECs were first evident in embryos 24-26 hours post-fertilisation (h.p.f.), and embryos developed a behavioural response to hypoxia between 24-48 h.p.f. The total number of NECs declined with age from approximately 300 cells per larva at 3 days post-fertilisation (d.p.f.) to about 120 cells at 7 d.p.f., and were rarely observed in adults. Acclimation to hypoxia (30 mmHg) or hyperoxia (300 mmHg) resulted in delayed or accelerated development, respectively, of peak resting ventilatory frequency and produced changes in the ventilatory response to hypoxia. In hypoxia-acclimated larvae, the temporal pattern of skin NECs was altered such that the number of cells did not decrease with age. By contrast, hyperoxia produced a more rapid decline in NEC number. The neurotoxin, 6-hydroxydopamine, degraded catecholaminergic nerve terminals that made contact with skin NECs and eliminated the hyperventilatory response to hypoxia. These studies indicate that skin NECs are sensitive to changes in O2 and suggest that they may play a role in initiating responses to hypoxia in developing zebrafish.
Prolactin regulates luminal bicarbonate secretion in the intestine of the sea bream (Sparus auratus L.)
Authors: Ferlazzo Antonella , Carvalho Edison S.M. , Gregorio Silvia F. , Power Deborah M. , Canario Adelino V.M. , Trischitta Francesca , Fuentes Juan
Published: August 2012

The pituitary hormone prolactin (PRL) is a pleiotropic endocrine factor that plays a major role in the regulation of ion balance in fish, with demonstrated actions mainly in the gills and kidney. The role of PRL in intestinal ion transport remains little studied. In marine fish, that have high drinking rates epithelial bicarbonate secretion in the intestine produces luminal carbonate aggregates believed to play a key role in water and ion homeostasis. The present study was designed to establish the putative role of PRL in the regulation of intestinal bicarbonate secretion (BCS) in a marine fish. Basolateral addition of PRL to the anterior intestine of the sea bream mounted in Ussing chambers causes a rapid (<20 min) decrease of BCS measured by pH-stat. A clear inhibitory dose response curve is obtained, with a maximal inhibition of 60-65% of basal BCS. The threshold concentration of PRL with a significant effect on BCS is 10 ng.ml-1, which is comparable with putative plasma levels in seawater fish. The effect of PRL on apical BCS is independent of the generation route for bicarbonate, as shown in a preparation devoid of basolateral HCO3- /CO2 buffer. In addition, specific inhibitors of JAK2 (AG-490, 50μM), PI3K (LY-294002, 75μM) or MEK (U-012610, 10μM) cause a 50-70% reduction in the effect of PRL on BCS, and demonstrate the involvement of PRL receptors. In addition to rapid effects, PRL actions are mediated at a genomic level. Incubation of intestinal explants of anterior intestine of the sea bream in vitro for 3 hours demonstrates a specific effect of PRL on expression of Slc4a4A (Na+-HCO3- co-transporter), but not on Slc26a6A or Slc26a3B (Cl-/ HCO3-- exchangers). We propose a new role for PRL in the regulation of BCS, an essential function for ion/water homeostasis in the intestine of marine fish.
Autonomous measurement of ingestion and digestion processes in free swimming sharks
Authors: Meyer Carl , Holland Kim
Published: August 2012

Direct measurement of predator feeding events would represent a major advance in marine trophic ecology. To date, devices available for empirically quantifying feeding in free-swimming fishes have relied on measuring stomach temperature, pH or physical motility, each of which has major, practical limitations. We hypothesized that the considerable physical changes which occur in the stomachs of carnivorous predators during the processes of ingestion and digestion should be quantifiable using Bulk Electrical Impedance measured across paired electrodes. We used a prototype archival data logging tag (Wildlife Computers Inc. Redmond, WA) to record changes in impedance inside the stomachs of captive, free swimming tiger and sandbar sharks over multiple, successive feeding events. Feeding and digestion events produced characteristic changes in electrical impedance of the stomach contents identifiable as 5 successive phases: (1) Pre-ingestion (empty stomach), (2) Ingestion, (3) Chemical 'lag' phase, (4) Mechanical 'chyme' phase, and (5) Stomach emptying phase. The duration of the chyme phase was positively related to meal size.
Fiscal Spending Jobs Multipliers: Evidence from the 2009 American Recovery and Reinvestment Act
Authors: Wilson Daniel J
Published: August 2012

This paper estimates the “jobs multiplier” of fiscal stimulus spending using the state-level allocations of federal stimulus funds from the American Recovery and Reinvestment Act (ARRA) of 2009. Because the level and timing of stimulus funds that a state receives was potentially endogenous, I exploit the fact that most of these funds were allocated according to exogenous formulary allocation factors such as the number of federal highway miles in a state or its youth share of population. Cross-state IV results indicate that ARRA spending in its first year yielded about eight jobs per million dollars spent, or $125,000 per job. (JEL E24, E62, H72, H75, R23)
Immunoglobulin A deficiency on serological coeliac screening: an opportunity for early diagnosis of hypogammaglobulinaemia
Authors: Bright P , Lock R J , Unsworth D J
Published: August 2012

We present a serendipitous case of clinically significant pan-hypogammaglobulinaemia, diagnosed after routine serological testing for possible coeliac disease led first to identification of IgA deficiency (discovered as a low background in IgA-based routine serological screening), and subsequently to confirmed pan-hypogammaglobulinaemia (antibody immunodeficiency). Hypogammaglobulinaemia is a relatively rare diagnosis (estimated at 1 in 36,000), in which delayed diagnosis and treatment are associated with chronic organ damage including bronchiectasis. Routine serological testing for coeliac disease using the IgA anti-tissue transglutaminase (IgA TTG) test is in widespread use and provides an opportunity for early diagnosis of hypogammaglobulinaemia. Routine serological screening for coeliac disease may uncover IgA deficiency, and we suggest that all IgA-deficient cases identified should also be checked for antibody deficiency by quantifying the other immunoglobulins (IgG, IgM).
Dose-dependent response of dendritic cells to 7-thia-8-oxo-guanosine and its modulation by polyinosinic:polycytidylic acid
Authors: Dzopalic Tanja , Dragicevic Ana , Bozic Biljana , Rajkovic Ivan , Colic Miodrag
Published: August 2012

Targeting the endosomal Toll-like receptors (TLRs) by specific agonists seems to be a promising tool for stimulation of the immunogenicity of dendritic cells (DCs). Since the functional outcome upon the engagement of TLRs may be different, the aim of our study was to examine if and how different concentrations of 7-thia-8-oxo-guanosine (7-TOG), a selective TLR7 agonist, influence differentiation, maturation and functions of human monocyte-derived DCs (MoDCs) and if its effects on MoDCs could be modulated by co-ligation of TLR3. Immature MoDCs were treated with different concentrations of 7-TOG (25, 100 and 250 μmol/L) alone, or together with polyinosinic:polycytidylic acid, Poly (I:C) (10 ng/mL), a selective TLR3 agonist, for an additional 48 h. We showed that the highest concentration of 7-TOG stimulated the differentiation, maturation and allostimulatory capability of MoDCs. These changes were accompanied by an increased production of interleukin 12 (IL-12) and induction of T helper (Th)1 and Th17 immune responses. Both Th responses were significantly augmented by additional stimulation of MoDCs with Poly (I:C). The treatment of MoDCs with the intermediate concentration of 7-TOG resulted in the up-regulation of co-stimulatory molecule (CD86) and increased production of IL-1 β and IL-6 by MoDCs, followed by the stimulation of the Th17 immune response. The lowest concentration of 7-TOG down-regulated the expression of CD40 on MoDCs and potentiated the Th2 immune response. The Th2 response was not significantly modulated by additional treatment of MoDCs with Poly (I:C), but this combination of TLR3/TLR7 agonists also stimulated both Th1 and Th17 responses. In conclusion, our results show that 7-TOG influences the phenotype and functions of MoDCs in a dose-dependent manner and suggests that fine-tuned signaling through TLR7 may be modified by the engagement of TLR3, resulting in a different outcome of immune response.
Porosome: the secretory portal
Authors: Jena Bhanu P
Published: August 2012

‘It seems terribly wasteful that, during the release of hormones and neurotransmitters from a cell, the membrane of a vesicle should merge with the plasma membrane to be retrieved for recycling only seconds or minutes later.’ – Erwin Neher, Nature 1993;363:497–498. This insightful statement so appropriately put, clearly reflected on the perception that secretory vesicles completely merge at the cell plasma membrane, failing to justify the generation of partially empty secretory vesicles in cells following secretion. A rational cellular mechanism would employ the transient fusion of secretory vesicles at the cell plasma membrane without compromising vesicle integrity, combined with vesicle retrieval following partial discharge of contents, to generate such partially empty vesicles following secretion. This hypothesis was finally confirmed with the serendipitous discovery of the porosome almost 16 years ago. The porosome has been demonstrated to be the universal secretory portal in cells and is present at the cell plasma membrane. In the past decade, the composition of the porosome, its dynamics, its structure at nanometer resolution in realtime using atomic force and electron microscopy, and its functional reconstitution into artificial lipid membrane, has resulted in a paradigm shift and a molecular understanding of the secretory process in cells. A brief background on porosome discovery, and our current understanding of its structure and function is summarized in this Minireview.
Severe and complicated Plasmodium vivax malaria in children
Authors: Jat Kana Ram , Guglani Vishal , Khairwa Anju
Published: August 2012

Plasmodium vivax, thought to be benign until recently, has been associated with severe malaria and its complications. This retrospective study describes severe and complicated P. vivax malaria in children. It affected almost all of the organ systems and the most commonly found complications were thrombocytopenia and severe anaemia. All children with malaria, including malaria caused by P. vivax, should be monitored for such complications.
A Broader View of Designing the Liver Allocation System
Authors: Akan Mustafa , Alagoz Oguzhan , Ata Baris , Erenay Fatih Safa , Said Adnan
Published: August 2012

We consider the problem of designing an efficient system for allocating donated livers to patients waiting for transplantation. The trade-off between medical urgency and efficiency is at the heart of the liver allocation problem. We model the transplant waiting list as a multiclass fluid model of overloaded queues, which captures the disease evolution by allowing the patients to switch between classes, i.e., health levels. We consider the bicriteria objective of minimizing total number of patient deaths while waiting for transplantation (NPDWT) and maximizing total quality-adjusted life years (QALYs) through a weighted combination. On one hand, under the objective of minimizing NPDWT, the current policy of United Network for Organ Sharing (UNOS) emerges as the optimal policy, providing a theoretical justification for the current practice. On the other hand, under the metric of maximizing QALYs, the optimal policy is an intuitive dynamic index policy that ranks patients based on their marginal benefit from transplantation, i.e., the difference in benefit with versus without transplantation. Finally, we perform a detailed simulation study to compare the performances of our proposed policies and the current UNOS policy along the following metrics: total QALYs, NPDWT, number of patient deaths after transplantation, number of total patient deaths, and number of wasted livers. Numerical experiments show that our proposed policy for maximizing QALYs outperforms the current UNOS policy along all metrics except the NPDWT.
Bullwhip Effect Measurement and Its Implications
Authors: Chen Li , Lee Hau L.
Published: August 2012

The bullwhip effect, or demand information distortion, has been a subject of both theoretical and empirical studies in the operations management literature. In this paper, we develop a simple set of formulas that describe the traditional bullwhip measure as a combined outcome of several important drivers, such as finite capacity, batch-ordering, and seasonality. Our modeling framework is descriptive in nature as it features certain plausible approximations that are commonly employed in practical inventory systems. The results are nonetheless compelling and can be used to explain various conflicting observations in previous empirical studies. Building on the theoretical framework, we discuss the managerial implications of the bullwhip measurement. We show that the measurement can be completely noninformative about the underlying supply chain cost performance if it is not linked to the operational details (such as decision intervals and leadtimes). Specifically, we show that an aggregated measurement over relatively long time periods can mask the operational-level bullwhip. In addition, we show that masking also exists under product or location aggregation in some illustrative cases.
A Variational Inequality Reformulation of a Congested Transit Assignment Model by Cominetti, Correa, Cepeda, and Florian
Authors: Codina Esteve
Published: August 2012

In the paper by Cominetti and Correa (2001) [Common-lines and passenger assignment in congested transit networks. Transportation Sci. 35(3):250–267], an extension to the common-lines problem for general multidestination networks under congestion is analyzed. Their transit equilibrium assignment model allows for a full representation of congestion effects caused by the variation of effective frequencies experienced by passengers at transit stops. This model is the first to address these characteristics consistently with the concept of strategies. In a subsequent paper by Cepeda, Cominetti, and Florian (2006) [A frequency-based assignment model for congested transit networks with strict capacity constraints: Characterization and computation of equilibria. Transportation Res. 40B(6):437–459], the computation of equilibrium is performed heuristically by the minimization of a gap function, using the method of successive averages. In this paper, a reformulation of this congested transit equilibrium assignment model is performed, demonstrating that the problem can be expressed as an equivalent variational inequality. The case of strictly capacitated transit networks is explored under the scope of this new reformulation, and new, broader conditions for the existence of solutions to this congested transit assignment model are determined.
The Simultaneous Vehicle Scheduling and Passenger Service Problem
Authors: Petersen Hanne L. , Larsen Allan , Madsen Oli B. G. , Petersen Bjørn , Ropke Stefan
Published: August 2012

Passengers using public transport systems often experience waiting times when transferring between two scheduled services. In this paper we propose a planning approach that seeks to obtain a favourable trade-off between the two contrasting objectives, passenger service and operating cost, by modifying the timetable. The planning approach is referred to as the simultaneous vehicle scheduling and passenger service problem (SVSPSP). The SVSPSP is modelled as an integer programming problem and solved using a large neighborhood search metaheuristic. The proposed framework is tested on data inspired by the express-bus network in the Greater Copenhagen area. The results are encouraging and indicate a potential decrease of passenger transfer waiting times in the network of up to 20%, with the vehicle scheduling costs remaining mostly unaffected.
BrdU Birth Dating Can Produce Errors in Cell Fate Specification in Chick Brain Development
Authors: Rowell Joanna J. , Ragsdale Clifton W.
Published: August 2012

Birth dating neurons with bromodeoxyuridine (BrdU) labeling is an established method widely employed by neurobiologists to study cell proliferation in embryonic, postnatal, and adult brain. Birth dating studies in the chick dorsal telencephalon and the mammalian striatum have suggested that these structures develop in a strikingly similar manner, in which neurons with the same birth date aggregate to form “isochronic clusters.” Here we show that isochronic cluster formation in the chick dorsal telencephalon is an artifact. In embryos given standardly employed doses of BrdU, we observed isochronic clusters but found that clusters were absent with BrdU doses close to the limits of detection. In addition, in situ hybridization experiments established that neurons in the clusters display errors in cell type specification: BrdU cell clusters in nidopallium adopted a mesopallial neuronal fate, mesopallial clusters were misspecified as nidopallial cells, and in some instances, the BrdU clusters failed to express neuronal differentiation markers characteristic of the dorsal telencephalon. These results demonstrate that the chick dorsal telencephalon does not develop by isochronic cluster formation and highlight the need to test the integrity of BrdU-treated tissue with gene expression markers of regional and cell type identity.
The Rates of Postmortem Proteolysis of Glutamate Transporters Differ Dramatically between Cells and between Transporter Subtypes
Authors: Li Yuchuan , Zhou Yun , Danbolt Niels Christian
Published: August 2012

Glutamate transporters (GLT-1, GLAST, EAAC1) limit the actions of excitatory amino acids. Because a disturbed transporter operation can cause or aggravate neurological diseases, transporters are of considerable neuropathological interest. Human samples, however, are seldom obtained fresh. Here, we used mice brains to study how fast glutamate transporters are degraded after death. Immunoblots showed that terminal GLT-1 epitopes (within residues 1–26 and 518–573) had mostly disappeared after 24 hr. GLAST termini (1–25 and 522–543) degraded slightly slower. In contrast, epitopes within central parts of GLT-1 (493–508) and the EAAC1 C-terminus (510–523) were readily detectable after 72 hr. The decline in immunoreactivity of the GLT-1 and GLAST termini was also seen in tissue sections, but proteolysis did not happen synchronously in all cells. At 24 hr, scattered cells remained strongly immunopositive, while the majority of cells were completely immunonegative. GLAST and GLT-1 co-localized in neocortical tissue, but at 12 hr, many GLAST-positive cells had lost the GLT-1 termini. The uneven disappearance of labeling was not observed with the antibodies to GLT-1 residues 493–508. The immunoreactivity to this epitope correlated better with the reported glutamate uptake activity. Thus, postmortem delay may affect epitopes differently, possibly causing erroneous conclusions about relative expression levels.
Plasma Adiponectin and the Risk of Hypertension in White and Black Postmenopausal Women
Authors: Wang Lu , Manson JoAnn E , Gaziano J Michael , Liu Simin , Cochrane Barbara , Cook Nancy R , Ridker Paul M , Rifai Nader , Sesso Howard D
Published: August 2012

BACKGROUND

Adiponectin may have a protective role in the development of obesity-related metabolic and vascular disorders, including hypertension. We conducted a prospective, nested case control study to investigate the relation between baseline plasma adiponectin, measures of adiposity, and subsequent risk of hypertension.

METHODS

We selected 400 white and 400 black postmenopausal women, age <70 years, who developed incident hypertension during 5.9-year follow-up and an equal number of age- and race-matched controls in the Women's Health Initiative Observational Study. We measured plasma concentrations of total adiponectin in their baseline blood samples.

RESULTS

In crude matched models, plasma adiponectin was inversely associated with risk of hypertension among both white and black women. The association appeared to be nonlinear in white women but dose related in black women. Adjustment for lifestyle factors, measures of obesity, and obesity-related clinical factors attenuated these associations. The multivariable relative risk (95% CI) of hypertension across increasing quartiles of plasma adiponectin were 1.00, 0.98 (0.66–1.46), 0.63 (0.41–0.97), and 0.92 (0.60–1.42) in white women (Ptrend: 0.38) and 1.00, 0.96 (0.64–1.46), 0.83 (0.53–1.29), and 0.58 (0.36–0.94) in black women (Ptrend: 0.02). Further adjustment for inflammatory markers and endothelial markers eliminated the association in white, but not black, women.

CONCLUSIONS

In this prospective, nested case control study, we found an inverse association between plasma adiponectin and risk of hypertension in white and black postmenopausal women. The reduced risk of hypertension was limited to only intermediate concentrations of adiponectin in white women whereas it was graded across quartiles of adiponectin in black women.
Auswertung resistiver Brücken bei minimierter Leistungsaufnahme
Authors: Stöhr Ingmar , Werthschützky Roland
Published: August 2012

Es wird ein Konzept zur energieminimalen Auswertung resistiver Brücken vorgestellt. Resistive Sensoren sind ausgereift und weit verbreitet. In energieautarken Systemen haben sie gegenüber kapazitiven Sensoren jedoch den Nachteil eines hohen Stromverbrauchs. Indem die Brücke nur noch zu den Abtastzeitpunkten des AD-Wandlers mit Strom versorgt wird, kann bis zu 99,9% der Energie für den Betrieb des Sensors eingespart werden. Grenzen auf Grund elektrischer und thermischer Ausgleichsvorgänge werden diskutiert.
SpeedSim: Made to Exit!
Authors: Zafar Naeem , Chang Victoria
Published: August 2012

The SpeedSim case study focuses on how mergers and acquisitions work in startup and entrepreneurial environments. It describes how an intelligent East Coast engineer built an extremely frugal company with a goal for acquisition and how the SpeedSim team masterfully executed and maximized their return by starting, growing, and selling a company. The case analyzes the process of how small companies position themselves to be acquired and how an acquirer assesses a company. The case can be used for mergers and acquisition and exit discussions, as well as for culture and organizational behavior discussions for entrepreneurship curriculums.
Low abundance plasma proteins in labour
Authors: Yuan Wei , Heesom Kate , Phillips Robert , Chen Lina , Trinder Jo , López Bernal Andrés
Published: August 2012

Every year, millions of births worldwide are complicated by prematurity or difficult post-term deliveries, resulting in a high incidence of perinatal mortality and morbidity. Our poor understanding of human parturition is a key reason for our inability to improve the management of preterm and post-term birth. In this study, we used proteomic techniques to look into protein changes in placental blood plasma obtained from women before or after spontaneous or induced labour, with vaginal or caesarean section deliveries. Our aim was to understand the basic mechanisms of human parturition regardless of whether the signals that trigger labour are of maternal and/or fetal origin. We found proteins from 33 genes with significantly altered expression profiles in relation to mode of labour and delivery. Most changes in labour occurred in proteins associated with ‘immune and defence responses’. Although the signal transduction and regulation of these pathways varied among modes of delivery, hepatocyte nuclear factor 1 homeobox A emerged as a shared protein in the mechanism of labour. Moreover, several apolipoproteins such as apolipoprotein A-IV and APOE were found to change with labour, and these changes were also confirmed in maternal plasma. This study has identified significant protein changes in placental intervillous plasma with labour and has revealed several pathways related to human parturition.
Genome-Wide Association Mapping in Tomato (Solanum lycopersicum) Is Possible Using Genome Admixture ofSolanum lycopersicumvar.cerasiforme
Authors: Ranc Nicolas , Muños Stephane , Xu Jiaxin , Le Paslier Marie-Christine , Chauveau Aurélie , Bounon Rémi , Rolland Sophie , Bouchet Jean-Paul , Brunel Dominique , Causse Mathilde
Published: August 2012

Genome-wide association mapping is an efficient way to identify quantitative trait loci controlling the variation of phenotypes, but the approach suffers severe limitations when one is studying inbred crops like cultivated tomato (Solanum lycopersicum). Such crops exhibit low rates of molecular polymorphism and high linkage disequilibrium, which reduces mapping resolution. The cherry type tomato (S. lycopersicum var. cerasiforme) genome has been described as an admixture between the cultivated tomato and its wild ancestor, S. pimpinellifolium. We have thus taken advantage of the properties of this admixture to improve the resolution of association mapping in tomato. As a proof of concept, we sequenced 81 DNA fragments distributed on chromosome 2 at different distances in a core collection of 90 tomato accessions, including mostly cherry type tomato accessions. The 81 Sequence Tag Sites revealed 352 SNPs and indels. Molecular diversity was greatest for S. pimpinellifolium accessions, intermediate for S. l. cerasiforme accessions, and lowest for the cultivated group. We assessed the structure of molecular polymorphism and the extent of linkage disequilibrium over genetic and physical distances. Linkage disequilibrium decreased under r2 = 0.3 within 1 cM, and minimal estimated value (r2 = 0.13) was reached within 20 kb over the physical regions studied. Associations between polymorphisms and fruit weight, locule number, and soluble solid content were detected. Several candidate genes and quantitative trait loci previously identified were validated and new associations detected. This study shows the advantages of using a collection of S. l. cerasiforme accessions to overcome the low resolution of association mapping in tomato.
Resampling QTL Effects in the QTL Sign Test Leads to Incongruous Sensitivity to Variance in Effect Size
Authors: Rice Daniel P , Townsend Jeffrey P
Published: August 2012

Allelic effects at quantitative trait loci (QTL) between lineages are potentially informative for indicating the action of natural selection. The QTL Sign Test uses the number of + and − alleles observed in a QTL study to infer a history of selection. This test has been constructed to condition on the phenotypic difference between the two lines in question. By applying the test to QTL data simulated under selection, we demonstrate that conditioning on the phenotypic difference results in a loss of power to reject the neutral hypothesis and marked sensitivity to variation in locus effect magnitude.
Rebitagem por fricção ("FricRiveting"). Desenvolvimento de uma nova técnica de união para juntas híbridas do tipo polímero-metal. Parte I: processo e microestrutura
Authors: Amancio-Filho Sergio T.
Published: August 2012

A rebitagem por fricção (do Inglês "Friction Riveting") é uma nova técnica de união pontual desenvolvida para a fabricação de estruturas híbridas do tipo polímero-metal. Nesta técnica, um rebite metálico cilíndrico é usado para unir um ou mais componentes termoplásticos. O processo de união ocorre através da plastificação e forjamento da extremidade do rebite via calor friccional, oriundo da rotação e pressão axial do rebite em contato com os componentes a serem unidos. Vantagens dessa nova técnica de união são, entre outras, ciclos de união curtos associados com a ausência ou diminuição do tempo de preparação das superfícies dos componentes, ausência de emissões tóxicas, e simplicidade operacional. Juntas rebitadas por fricção apresentam elevada resistência mecânica. Nesse artigo a viabilidade da técnica foi demonstrada através de um estudo de caso em juntas de polieterimida com rebites de alumínio 2024-T351. Juntas com elevada resistência mecânica (com valores médios de até 93% da resistência à tração do rebite) foram produzidas e caracterizadas em termos de microestrutura (microscopia ótica, de varredura e por microtomografia computadorizada).
The pyroclastic dyke and welded crystal tuff of the Morro dos Gatos alkaline intrusive complex, State of Rio de Janeiro, Brazil
Authors: Motoki Akihisa , Geraldes Mauro Cesar , Iwanuch Woldemar , Vargas Thais , Motoki Kenji Freire , Balmant Alex , Ramos Marina Nascimento
Published: August 2012

The present article reports the geologic, lithologic, and petrographic characteristics of the pyroclastic dyke and phenocryst-rich welded crystal tuff of the Morro dos Gatos alkaline intrusive body, State of Rio de Janeiro, Brazil. The intrusive complex has an extension of 1.2 x 0.8 km occupying an area of 0.5 km². It is constituted mainly by monzonite and trachyte. At the south flank of the massif, there exits a pyroclastic dyke and at the northwest flank, an intrusive welded crystal tuff. The pyroclastic dyke is 40 to 80 cm wide and intrudes into the basement porphyritic granite. This rock is constituted by welded tuff breccia with large amount of lapilli-size angular lithic fragments of trachyte. Along the contact plane of this dyke, there is an intercalation of the trachyte. The crystal tuff is characterised by abundant alkaline feldspar phenocrysts and mineral fragments of alkaline feldspar, quartz, biotite, and amphibole, showing a crystal matrix-supported texture. Large phenocrysts are aggregations of idiomorphic alkaline feldspar crystals with a general size of 2 mm and a maximum one of 6 mm. The matrix is composed mainly of mineral fragments of less than 1 mm in general size. The size-frequency diagram for the mineral fragments suggests that they have been originated from an explosive eruption. The matrix is strongly welded and completely devitrified showing a cryptocrystalline texture. The crystals were concentrated by sorting with the help of the volcanic gas ascending in the volcanic conduit during a continuous and effusive phase of the eruption. The limited special distribution of the pyroclastic rocks and small outcrop size indicate that they are not constituent of pyroclastic flow deposits, but of subvolcanic conduit and fissure.
Síntese sobre ofiolitos: evolução dos conceitos
Authors: Queiroga Gláucia Nascimento , Suita Marcos Tadeu de Freitas , Pedrosa-Soares Antônio Carlos , Martins Maximiliano de Souza , Pinheiro Marco Aurélio Piacentini
Published: August 2012

Ofiolitos são fragmentos de antigas litosferas oceânicas formados em margens de placa construtivas ou divergentes transformantes. Por meio de extensos falhamentos de empurrão, esses corpos ou parte deles são colocados na crosta continental, dentro de pacotes de rochas dos cinturões orogênicos, em estado sólido, mas podendo estar, ainda, relativamente quentes. Os possíveis ambientes produtores de litosfera oceânica incluem cadeias meso-oceânicas, bacias relacionadas a arcos-de-ilhas juvenis e bacias de retroarco. Ofiolitos de idade fanerozoica são abundantes em cinturões orogênicos ao redor do mundo, enquanto que os remanescentes oceânicos do Pré-Cambriano são pouco comuns e encontram-se distribuídos, principalmente, na Finlândia, Canadá, Marrocos, Arábia Saudita, Egito, Rússia, Brasil e China. Diversos registros de remanescentes oceânicos pré-cambrianos de diferentes idades foram reconhecidos no Brasil. A maioria desses corpos situa-se nas faixas orogênicas brasilianas e registra o consumo dos oceanos neoproterozóicos. A partir do que foi exposto, esse trabalho procura sintetizar as principais informações acerca de sequências ofiolíticas, trazendo uma breve revisão de conceitos e classificações ao longo dos quase 200 anos de utilização desse termo.
Atividade pozolânica de arenito zeolítico da região Nordeste do Brasil
Authors: Picanço Marcelo de Souza , Angélica Rômulo Simões , Barata Márcio Santos
Published: August 2012

No nordeste do Brasil, existe a ocorrência de zeolitas sedimentares relacionadas a arenitos, descoberta nos anos 2000. Esses arenitos são constituídos de quartzo, zeolitas naturais (estilbita) e argilominerais (esmectita). Estudos preliminares constataram que esse arenito pode ser empregado como material pozolânico em sistemas à base de cimento Portland, desde que o material seja peneirado para remoção do quartzo e ativado termicamente, uma vez que a estilbita é zeolita de baixa atividade pozolânica. O objetivo geral desse trabalho foi determinar qual a fração granulométrica que proporciona a maior concentração de zeolita e esmectita e a temperatura de calcinação que acarreta a maior atividade pozolânica. No programa experimental, empregou-se o arenito zeolítico passante nas peneiras #200 e #325 e calcinado às temperaturas de 150ºC, 300ºC e 500ºC. A análise da caracterização mineralógica das amostras peneiradas foi realizada por difração de raios X, por análises termogravimétrica e termodiferencial. Para avaliação da reatividade, foram realizados ensaios mecânicos de atividade pozolânica em argamassas de cal hidratada e cimento Porltand. Os resultados mostraram que a amostra peneirada na peneira #200 foi a mais adequada porque apresentou elevada concentração de estilbita e um percentual maior de material passante em comparação a amostra da peneira #325, 15% e 2% respectivamente. A temperatura de calcinação de 500ºC foi a que proporcionou a maior atividade pozolânica, em razão da modificação mais efetiva da estrutura cristalina, tanto da estilbita, como da esmectita. As temperaturas mais moderadas a 150ºC e 300ºC não foram suficientes para a obtenção dos mesmos resultados. As argamassas com o arenito passante na peneira #200 e calcinado a 500ºC atingiram os valores limites mínimos exigidos para que um material seja considerado pozolânico, no caso, 6 MPa para argamassas de cal hidratada e 75% para o índice de atividade pozolânica (IAP).
Propriedades mecânicas de compósitos cimentícios produzidos com lodo de estação de tratamento de efluentes da indústria de batata pré-fritas
Authors: Resende Domingos Sávio de , Bezerra Augusto Cesar da Silva , Gouveia Antonio Maria Claret de
Published: August 2012

O grande volume de resíduos sólidos industriais gerados pela indústria de batatas pré-fritas e o alto custo do seu manejo estimulam pesquisas em busca de soluções mais adequadas para a sua destinação final. Esse trabalho caracterizou o resíduo sólido (lodo) de Estação de Tratamento de Efluentes (ETE) de indústria de batatas. O lodo foi processado através de secagem, desidratação, moagem e peneiramento. Para a caracterização do lodo foram utilizadas técnicas de granulometria a laser, microscopia eletrônica de varredura (MEV) com espectrômetro de raios X dispersivo em energia (EDS), difração de raio X, análise térmica diferencial (DTA), termogravimétrica (TGA) e perda ao fogo. Após a caracterização, o lodo foi utilizado para a confecção de compósitos cimentícios, em substituição parcial do cimento, em massa equivalente para substituição do mesmo volume, determinado pelas massas específicas de ambos materiais, nas porcentagens de 3, 5, 7 e 10%. Os compósitos foram ensaiados para a obtenção da resistência à compressão e do módulo de elasticidade dinâmico. A utilização do lodo de ETE como pozolana foi descartada, tendo-se como base o resultado do ensaio de perda ao fogo. Nos ensaios mecânicos realizados, nota-se que a adição de lodo, em substituição parcial ao cimento, impactou, negativamente, de forma mais relevante a resistência à compressão. Tais ensaios foram considerados satisfatórios para os compósitos com substituição do cimento por 3% e 5% de lodo.
Subvolcanic neck of Cabugi Peak, state of Rio Grande do Norte, Brazil, and origin of its landform
Authors: Motoki Akihisa , Campos Thomas Ferreira da Costa , Fonseca Vanildo Pereira da , Motoki Kenji Freire
Published: August 2012

This article reports geologic, petrographic, and geomorphological observations of the mafic alkaline subvolcanic neck of the Cabugi Peak, located in the State of Rio Grande do Norte, Brazil. The massif is 370 m high and has 0.4 km³ of total volume. It is constituted mainly by Caicó orthogneiss. The neck is exposed on the top of the massif forming a conical morphologic protrusion with relative height of 160 m and diameter of 500 m. The volume of the mafic alkaline rock is 0.056 km³ occupying 14% of the whole massif. The general form of the massif is strongly convex with the MCI (Macro Concavity Index) of -2.3. The neck is constituted by olivine-rich alkaline micro-gabbro in the centre and alkaline dolerite at the contact zone. There are well-developed cooling columnar joints with typical diameter of 60 cm. They are steep at the centre of the neck and sub-horizontal at the contact zone. On the foothill surface, called Sertaneja surface, no outcrops of mafic alkaline lava, other eruptive deposits, or volcanic rock debris have been observed. These observations allow a conclusion that the volcanic edifice and eruptive deposits of the late Oligocene were completely removed by later uplift and consequent regional denudation and that the present-day surface is significantly lower than that of the eruption time. The outcrops of the Cabugi Peak exhibit the underground geologic structure of the late Oligocene volcano. The original volcano form is not preserved anymore and the present morphologic elevation is attributed to differential erosion of the subvolcanic neck. According to the volcanological definition, the present-day morphology of the Cabugi Peak is not classified as an extinct volcano.
Um estudo comparativo entre chapas produzidas pelos processos de lingotamento contínuo e de lingotamento semicontínuo da liga AA4006: microestrutura e textura cristalográfica
Authors: Souza Fabrício Mendes , Lima Nelson Batista de , Plaut Ronald Lesley , Fernandes Ricardo do Carmo , Padilha Angelo Fernando
Published: August 2012

Nesse trabalho, foi realizado um estudo comparativo da microestrutura e da textura cristalográfica entre chapas da liga AA4006 produzidas por dois processos industriais de lingotamento: contínuo (Twin roll caster TRC) e semicontínuo (Direct chill DC). Para a caracterização microestrutural, foram utilizadas as técnicas de microscopia óptica com luz polarizada, microscopia eletrônica de varredura, medidas de condutividade elétrica e ensaios de dureza Brinell. A textura cristalográfica foi determinada por difração de raios X. Foram detectadas e discutidas diferenças significativas nas morfologias e distribuições de grãos e de partículas de fases intermetálicas. O estudo da textura cristalográfica foi realizado ao longo da espessura das tiras e os resultados mostraram variações significativas da textura entre as chapas ao longo da espessura. A chapa produzida por lingotamento contínuo apresentou uma típica textura de cisalhamento, nas proximidades de sua superfície, enquanto que, nas regiões mais internas, a fibra β foi observada.
Parâmetros de dispersão de ar em células mecânicas de flotação em usinas brasileiras
Authors: Ojeda Ricardo José Montesinos , Lima Odair Alves de , Zanin Massimiliano , Leal Filho Laurindo de Salles
Published: August 2012

O objetivo desse trabalho é apresentar e discutir a determinação dos parâmetros de dispersão de ar em células mecânicas de flotação, em circuitos industriais brasileiros. Foram investigados os circuitos rougher e scavenger das usinas RPM, Taquari-Vassouras, Copebras e Fosfértil-Catalão (atual Vale Fertilizantes). Nas usinas RPM e Taquari-Vassouras, foram determinados a velocidade superficial do ar (Jg), o hold-up do ar (εg), o diâmetro médio de bolhas (d32) e o fluxo de área superficial de bolhas (Sb). Para as outras usinas, foram determinados somente o Jg e εg. Os resultados mostraram que, com exceção da RPM, todos os circuitos investigados apresentaram baixos valores para os parâmetros de dispersão do ar. Taquari-Vassouras apresentou os mais baixos valores médios para Jg e εg, respectivamente, 0,05 cm/s e 5%. Os maiores valores de Jg foram determinados no circuito rougher da Copebras, 1,17 cm/s, ao passo que a RPM apresentou os maiores valores para o hold-up e tamanho de bolha, respectivamente, 31% e 2,61mm. Os valores obtidos, para Sb, situaram-se abaixo daqueles reportados na literatura.
Untangling the influence of ecological and evolutionary factors on trait variation across hummingbird assemblages
Authors: Graham Catherine H. , Parra Juan L. , Tinoco Boris A. , Stiles F. Gary , McGuire Jim A.
Published: August 2012

Phylogenetic community ecology combines phylogenetic hypotheses with local species composition and functional‐trait information to evaluate historical and contemporary mechanisms influencing local assemblage structure. Most studies assume that, if functional traits are conserved, then patterns of trait variation should match patterns of phylogenetic structure within local assemblages. Here we evaluated if we could predict trait structure by assuming that environmental filtering or biotic interactions work primarily on phylogenetically conserved functional traits. We investigated patterns of phylogenetic assemblage structure and functional‐trait variation in bill length, wing length, and body mass in 236 hummingbird assemblages (126 species) across two major gradients in northern South America: elevation and precipitation. While mean trait values for assemblages vary predictably based on empirical knowledge of hummingbird biology, the distribution of trait values within assemblages do not correspond to those predicted based on phylogenetic signal and phylogenetic structure. Instead, we were able to identify instances where assemblages have high levels of morphological variation despite their close evolutionary relatedness and vice versa. Our results provide support for both filtering and biotic interactions across gradients, as has been documented in other studies.
Sinks for nitrogen inputs in terrestrial ecosystems: a meta‐analysis of 15N tracer field studies
Authors: Templer P. H. , Mack M. C. , III F. S. Chapin , Christenson L. M. , Compton J. E. , Crook H. D. , Currie W. S. , Curtis C. J. , Dail D. B. , D'Antonio C. M. , Emmett B. A. , Epstein H. E. , Goodale C. L. , Gundersen P , Hobbie S. E. , Holland K , Hooper D. U. , Hungate B. A. , Lamontagne S , Nadelhoffer K. J. , Osenberg C. W. , Perakis S. S. , Schleppi P , Schimel J , Schmidt I. K. , Sommerkorn M , Spoelstra J , Tietema A , Wessel W. W. , Zak D. R.
Published: August 2012

Effects of anthropogenic nitrogen (N) deposition and the ability of terrestrial ecosystems to store carbon (C) depend in part on the amount of N retained in the system and its partitioning among plant and soil pools. We conducted a meta‐analysis of studies at 48 sites across four continents that used enriched 15N isotope tracers in order to synthesize information about total ecosystem N retention (i.e., total ecosystem 15N recovery in plant and soil pools) across natural systems and N partitioning among ecosystem pools. The greatest recoveries of ecosystem 15N tracer occurred in shrublands (mean, 89.5%) and wetlands (84.8%) followed by forests (74.9%) and grasslands (51.8%). In the short term (<1 week after 15N tracer application), total ecosystem 15N recovery was negatively correlated with fine‐root and soil 15N natural abundance, and organic soil C and N concentration but was positively correlated with mean annual temperature and mineral soil C:N. In the longer term (3–18 months after 15N tracer application), total ecosystem 15N retention was negatively correlated with foliar natural‐abundance 15N but was positively correlated with mineral soil C and N concentration and C : N, showing that plant and soil natural‐abundance 15N and soil C:N are good indicators of total ecosystem N retention. Foliar N concentration was not significantly related to ecosystem 15N tracer recovery, suggesting that plant N status is not a good predictor of total ecosystem N retention. Because the largest ecosystem sinks for 15N tracer were below ground in forests, shrublands, and grasslands, we conclude that growth enhancement and potential for increased C storage in aboveground biomass from atmospheric N deposition is likely to be modest in these ecosystems. Total ecosystem 15N recovery decreased with N fertilization, with an apparent threshold fertilization rate of 46 kg N·ha−1·yr−1 above which most ecosystems showed net losses of applied 15N tracer in response to N fertilizer addition.