bluuebunny/crossref_metadata_2025 huggingface dataset:
Dual accountability and the nationalization of party competition: Evidence from four federations
Authors: Rodden Jonathan , Wibbels Erik
Published: October 2010

This paper assesses the extent to which party systems are nationalized in four federations. In doing so, the research addresses two questions. First, is dual accountability operational across decentralized countries, or do sub-national voters turn to national cues as a means to economize in a complex information environment? By bringing a cross-national dataset to bear on this question, we are able to provide insight into where and why dual accountability might operate. Second, what explains variation in the extent to which party systems are nationalized across countries and time? We build on previous literature to suggest a number of factors likely to impact the extent of nationalization. We examine those factors in the context of provincial-level elections in Argentina, Canada, Germany and the United States. Using national and sub-national economic data, we find little evidence of dual accountability in any of our countries. We find that economic performance matters little for regional electoral outcomes, and where it does, sub-national outcomes reflect national rather than sub-national conditions. More important are the roles of partisan relations across levels of government and election timing. Sub-national co-partisans of the nationally governing party lose votes, particularly as the time from the most recent national election grows. The strength of these effects varies across our cases in predictable ways.
Doomed to disagree? Party-voter discipline and policy gridlock under divided government
Authors: Fernández-Albertos José , Lapuente Víctor
Published: October 2010

This article explains the existence of policy gridlock in systems with divided government, even when there are policies that are universally preferred to the status quo. It is shown analytically that one dimension of party institutionalization (the degree of party-voter discipline) may create incentives for veto players to block policies that, ideologically, they might like. This is the case because when party attachments dominate voters' behaviour across different electoral arenas, veto players in the opposition might find it in their electoral interests to prevent popular policies from being adopted. We illustrate our argument by analysing the recent experiences of two Latin American democracies living under divided government but with opposite levels of party-voter discipline: Mexico and Brazil. Contrary to the received wisdom, the low degree of party institutionalization in Brazil may have helped the passing of comprehensive policy reforms, whereas strongly institutionalized parties in Mexico might have been partly responsible for the persistence of policy gridlock.
Vascular disorders in athletes
Authors: Perlowski Alice A , Jaff Michael R
Published: October 2010

Athletes rarely present with symptoms or clinical findings suggestive of vascular disease. However, vascular etiologies should be considered when an athlete complains of persistent symptoms which are refractory to conservative therapies commonly used for presumed musculoskeletal injuries. A comprehensive history should be performed, with special consideration to the postures the athlete assumes repeatedly during their chosen sport. Musculoskeletal anatomy surrounding the vascular bed of interest should be thoroughly reviewed. Physical examination should include provocative maneuvers specific to the suspected vascular disorder. The proper use of noninvasive diagnostic studies, including duplex ultrasonography, computerized tomography (CT), and magnetic resonance imaging (MRI), along with catheter-based angiography, when indicated, can ensure prompt diagnosis. Appropriate, multifaceted treatment of an athlete affected by a vascular disorder can facilitate an expeditious return to previous levels of activity.
Securing the communication of medical information using local biometric authentication and commercial wireless links
Authors: Ivanov Vladimir I. , Yu Paul L. , Baras John S.
Published: October 2010

Medical information is extremely sensitive in nature — a compromise, such as eavesdropping or tampering by a malicious third party, may result in identity theft, incorrect diagnosis and treatment, and even death. Therefore, it is important to secure the transfer of medical information from the patient to the recording system. We consider a portable, wireless device transferring medical information to a remote server. We decompose this problem into two sub-problems and propose security solutions to each of them: (1) to secure the link between the patient and the portable device, and (2) to secure the link between the portable device and the network. Thus we push the limits of the network security to the edge by authenticating the user using their biometric information; authenticating the device to the network at the physical layer; and strengthening the security of the wireless link with a key exchange mechanism. The proposed authentication methods can be used for recording the readings of medical data in a central database and for accessing medical records in various settings.
Lung diseases directly associated with rheumatoid arthritis and their relationship to outcome
Authors: Tsuchiya Y. , Takayanagi N. , Sugiura H. , Miyahara Y. , Tokunaga D. , Kawabata Y. , Sugita Y.
Published: October 2010

The outcome and cause of death of each lung disease directly associated with rheumatoid arthritis (RA-LD) have been poorly investigated.

A retrospective study was conducted of 144 patients with RA-LD, in whom the median follow-up period after the initial visit for a respiratory examination was 4.5 yrs.

A total of 57 patients were identified with usual interstitial pneumonia (UIP), 31 with bronchiectasis, 16 with nonspecific interstitial pneumonia (NSIP), 11 with bronchiolitis, five with organising pneumonia (OP), five with diffuse alveolar damage (DAD) and 19 with combined disease. The 5-yr survival rates were 36.6% in the UIP group, 87.1% in the bronchiectasis group, 93.8% in the NSIP group, 88.9% in the bronchiolitis group, 60.0% in the OP group and 20.0% in the DAD group. Survival of patients with DAD was worse than that of patients with UIP. Overall, survival of patients with UIP was worse than that of patients with bronchiectasis, NSIP or bronchiolitis. Of the 144 patients, 71 (49.3%) died, of whom 58 (81.7%) died due to respiratory lesions.

Of patients with RA-LD, patients with DAD experienced the highest mortality, and the survival of patients with UIP was worse than that of patients with NSIP.
Do young adults with childhood asthma avoid occupational exposures at first hire?
Authors: Dumas O. , Smit L.A.M. , Pin I. , Kromhout H. , Siroux V. , Nadif R. , Vermeulen R. , Heederik D. , Hery M. , Choudat D. , Kauffmann F. , Le Moual N.
Published: October 2010

Information on the healthy worker hire effect in relation to asthma is scant. We aimed to assess whether and how childhood asthma-related characteristics (before hire) relate to occupational exposures at first hire.

Analyses were conducted in 298 children examined at the first survey of the Epidemiological Study on the Genetics and Environment of Asthma (1991–1995), who reported a training period or a job at follow-up in 2003–2007 (aged 17–29 yrs; 53% males). Exposure likelihood to dust, gases and/or fumes in their first occupation was estimated by the ALOHA job exposure matrix. Asthma before the first occupation and two asthma classifications for severity (Global Initiative for Asthma 2002 guidelines) and symptoms were defined by questionnaire.

In their first job, 47% of subjects were exposed. After adjustment (age, sex and education), pre-hire onset asthmatics (59%) were nonsignificantly less likely to be exposed (OR 0.67, 95% CI 0.41–1.11). Associations were stronger when considering those with severe asthma or high symptom score in childhood (OR 0.27 (95% CI 0.11–0.63) and OR 0.49 (95% CI 0.25–0.99), respectively). The association was observed in those who completed a university degree (OR 0.55, 95% CI 0.29–1.04) but not in the others (OR 0.98, 95% CI 0.44–2.22), with consistent results for all asthma characteristics.

Results suggest a healthy worker hire effect in subjects with more severe or more symptomatic asthma in childhood. Education may modulate self-selection.
Similarity of molecular phenotype between known epilepsy gene LGI1 and disease candidate gene LGI2
Authors: Limviphuvadh Vachiranee , Chua Ling Ling , Rahim Rabi 'Atul' Adawiyah Bte , Eisenhaber Frank , Maurer-Stroh Sebastian , Adhikari Sharmila
Published: October 2010

Background

The LGI2 (leucine-rich, glioma inactivated 2) gene, a prime candidate for partial epilepsy with pericentral spikes, belongs to a family encoding secreted, beta-propeller domain proteins with EPTP/EAR epilepsy-associated repeats. In another family member, LGI1 (leucine-rich, glioma inactivated 1) mutations are responsible for autosomal dominant lateral temporal epilepsy (ADLTE). Because a few LGI1 disease mutations described in the literature cause secretion failure, we experimentally analyzed the secretion efficiency and subcellular localization of several LGI1 and LGI2 mutant proteins corresponding to observed non-synonymous single nucleotide polymorphisms (nsSNPs) affecting the signal peptide, the leucine-rich repeats and the EAR propeller.

Results

Mapping of disease-causing mutations in the EAR domain region onto a 3D-structure model shows that many of these mutations co-localize at an evolutionary conserved surface region of the propeller. We find that wild-type LGI2 is secreted to the extracellular medium in glycosylated form similarly to LGI1, whereas several mutant proteins tested in this study are secretion-deficient and accumulate in the endoplasmic reticulum. Interestingly, mutations at structurally homologous positions in the EAR domain have the same effect on secretion in LGI1 and LGI2.

Conclusions

This similarity of experimental mislocalization phenotypes for mutations at homologous positions of LGI2 and the established epilepsy gene LGI1 suggests that both genes share a potentially common molecular pathogenesis mechanism that might be the reason for genotypically distinct but phenotypically related forms of epilepsy.
Assessment of orthologous splicing isoforms in human and mouse orthologous genes
Authors: Zambelli Federico , Pavesi Giulio , Gissi Carmela , Horner David S , Pesole Graziano
Published: October 2010

Background

Recent discoveries have highlighted the fact that alternative splicing and alternative transcripts are the rule, rather than the exception, in metazoan genes. Since multiple transcript and protein variants expressed by the same gene are, by definition, structurally distinct and need not to be functionally equivalent, the concept of gene orthology should be extended to the transcript level in order to describe evolutionary relationships between structurally similar transcript variants. In other words, the identification of true orthology relationships between gene products now should progress beyond primary sequence and "splicing orthology", consisting in ancestrally shared exon-intron structures, is required to define orthologous isoforms at transcript level.

Results

As a starting step in this direction, in this work we performed a large scale human- mouse gene comparison with a twofold goal: first, to assess if and to which extent traditional gene annotations such as RefSeq capture genuine splicing orthology; second, to provide a more detailed annotation and quantification of true human-mouse orthologous transcripts defined as transcripts of orthologous genes exhibiting the same splicing patterns.

Conclusions

We observed an identical exon/intron structure for 32% of human and mouse orthologous genes. This figure increases to 87% using less stringent criteria for gene structure similarity, thus implying that for about 13% of the human RefSeq annotated genes (and about 25% of the corresponding transcripts) we could not identify any mouse transcript showing sufficient similarity to be confidently assigned as a splicing ortholog. Our data suggest that current gene and transcript data may still be rather incomplete - with several splicing variants still unknown. The observation that alternative splicing produces large numbers of alternative transcripts and proteins, some of them conserved across species and others truly species-specific, suggests that, still maintaining the conventional definition of gene orthology, a new concept of "splicing orthology" can be defined at transcript level.
Renal protection in diabetes: lessons from ONTARGET®
Authors: Ritz Eberhard , Schmieder Roland E , Pollock Carol A
Published: October 2010

Hypertension is an important independent risk factor for renal disease. If hypertension and chronic renal disease co-exist, as is common in patients with diabetes mellitus, the risk of cardiovascular disease is heightened. The importance of rigorous blood pressure control is recognized in current guidelines, with a recommended target of office blood pressure of < 130/80 mmHg; although ambulatory blood pressure may be more appropriate in order to identify the 24-hour hypertensive burden. Even lower blood pressure may further reduce the progression of chronic kidney disease, but the incidence of cardiovascular events may increase. Albuminuria not only indicates renal damage, but is also a powerful predictor of cardiovascular morbidity and mortality at least in patients with high cardiovascular risk and potentially pre-existing vascular damage. Management of the multiple factors for renal and cardiovascular disease is mandatory in the diabetic patient. The renin-angiotensin system (RAS) plays a pivotal role in the progression of renal disease, as well as in hypertension and target-organ damage. The use of agents that target the RAS confer renoprotection in addition to antihypertensive activity. There is extensive evidence of the renoprotective effect of angiotensin II receptor blockers (ARBs), and specifically telmisartan. In addition to providing 24-hour blood pressure control, clinical studies in patients with diabetes show that telmisartan improves renal endothelial function, prevents progression from microalbuminuria to macroalbuminuria, slows the decline in glomerular filtration rate and reduces proteinuria in overt nephropathy. These effects cannot be solely attributed to blood pressure control. In contrast to other members of the ARB class, the renoprotective effect of telmisartan is not confined to the management of diabetic nephropathy; slowing the progression of albuminuria has been demonstrated in the ONgoing Telmisartan Alone and in combination with Ramipril Global Endpoint Trial (ONTARGET®), which included diabetic and non-diabetic patients at high risk of cardiovascular events.
A cell-permeable dominant-negative survivin protein induces apoptosis and sensitizes prostate cancer cells to TNF-α therapy
Authors: Cheung Chun Hei Antonio , Sun Xueying , Kanwar Jagat R , Bai Ji-Zhong , Cheng LiTing , Krissansen Geoffrey W
Published: October 2010

Background

Survivin is a member of the inhibitor-of-apoptosis (IAP) family which is widely expressed by many different cancers. Overexpression of survivin is associated with drug resistance in cancer cells, and reduced patient survival after chemotherapy and radiotherapy. Agents that antagonize the function of survivin hold promise for treating many forms of cancer. The purpose of this study was to investigate whether a cell-permeable dominant-negative survivin protein would demonstrate bioactivity against prostate and cervical cancer cells grown in three dimensional culture.

Results

A dominant-negative survivin (C84A) protein fused to the cell penetrating peptide poly-arginine (R9) was expressed in E. coli and purified by affinity chromatography. Western blot analysis revealed that dNSurR9-C84A penetrated into 3D-cultured HeLa and DU145 cancer cells, and a cell viability assay revealed it induced cancer cell death. It increased the activities of caspase-9 and caspase-3, and rendered DU145 cells sensitive to TNF-α via by a mechanism involving activation of caspase-8.

Conclusions

The results demonstrate that antagonism of survivin function triggers the apoptosis of prostate and cervical cancer cells grown in 3D culture. It renders cancer cells sensitive to the proapoptotic affects of TNF-α, suggesting that survivin blocks the extrinsic pathway of apoptosis. Combination of the biologically active dNSurR9-C84A protein or other survivin antagonists with TNF-α therapy warrants consideration as an approach to cancer therapy.
Drosophilatype II neuroblast lineages keep Prospero levels low to generate large clones that contribute to the adult brain central complex
Authors: Bayraktar Omer Ali , Boone Jason Q , Drummond Michael L , Doe Chris Q
Published: October 2010

Tissue homeostasis depends on the ability of stem cells to properly regulate self-renewal versus differentiation. Drosophila neural stem cells (neuroblasts) are a model system to study self-renewal and differentiation. Recent work has identified two types of larval neuroblasts that have different self-renewal/differentiation properties. Type I neuroblasts bud off a series of small basal daughter cells (ganglion mother cells) that each generate two neurons. Type II neuroblasts bud off small basal daughter cells called intermediate progenitors (INPs), with each INP generating 6 to 12 neurons. Type I neuroblasts and INPs have nuclear Asense and cytoplasmic Prospero, whereas type II neuroblasts lack both these transcription factors. Here we test whether Prospero distinguishes type I/II neuroblast identity or proliferation profile, using several newly characterized Gal4 lines. We misexpress prospero using the R19H09-Gal4 line (expressed in type II neuroblasts but no adjacent type I neuroblasts) or R9D11-Gal4 line (expressed in INPs but not type II neuroblasts). We find that differential prospero expression does not distinguish type I and type II neuroblast identities, but Prospero regulates proliferation in both type I and type II neuroblast lineages. In addition, we use R9D11 lineage tracing to show that type II lineages generate both small-field and large-field neurons within the adult central complex, a brain region required for locomotion, flight, and visual pattern memory.
Hypertonic stress regulates T cell function via pannexin-1 hemichannels and P2X receptors
Authors: Woehrle Tobias , Yip Linda , Manohar Monali , Sumi Yuka , Yao Yongli , Chen Yu , Junger Wolfgang G
Published: October 2010

Hypertonic stress activates T cells by inducing the controlled release of ATP through pannexin-1 hemichannels and activation of ATP-gated ion channels P2X1, P2X4, and P2X7.

Hypertonic saline (HS) resuscitation increases T cell function and inhibits posttraumatic T cell anergy, which can reduce immunosuppression and sepsis in trauma patients. We have previously shown that HS induces the release of cellular ATP and enhances T cell function. However, the mechanism by which HS induces ATP release and the subsequent regulation of T cell function by ATP remain poorly understood. In the present study, we show that inhibition of the gap junction hemichannel pannexin-1 (Panx1) blocks ATP release in response to HS, and HS exposure triggers significant changes in the expression of all P2X-type ATP receptors in Jurkat T cells. Blocking or silencing of Panx1 or of P2X1, P2X4, or P2X7 receptors blunts HS-induced p38 MAPK activation and the stimulatory effects of HS on TCR/CD28-induced IL-2 gene transcription. Moreover, treatment with HS or agonists of P2X receptors overcomes T cell suppression induced by the anti-inflammatory cytokine IL-10. These findings indicate that Panx1 hemichannels facilitate ATP release in response to hypertonic stress and that P2X1, P2X4, and P2X7 receptor activation enhances T cell function. We conclude that HS and P2 receptor agonists promote T cell function and thus, could be used to improve T cell function in trauma patients.
Synergism of NOD2 and NLRP3 activators promotes a unique transcriptional profile in murine dendritic cells
Authors: Conforti-Andreoni Cristina , Beretta Ottavio , Licandro Ginevra , Qian Hong Liang , Urbano Matteo , Vitulli Federico , Ricciardi-Castagnoli Paola , Mortellaro Alessandra
Published: October 2010

The NLR pathways activated by monosodium urate and muramyl dipeptide at a transcriptional level lead to a specific pro-inflammatory signatures.

NLRs are cytoplasmic proteins that sense cellular stress and intracellular damage resulting from pathogen uptake. To date, the role of NLRs has been studied using combinations of NLR and TLR agonists, but the interplay between two different NLRs remains uncharacterized. In this study, we employed microarrays to investigate in DCs the regulation of gene transcription mediated by activation of NOD2 and NLRP3 pathways using MDP and MSU. MDP and MSU co-stimulation of murine BMDCs up-regulated the expression of genes encoding molecules for antigen presentation and co-stimulation (MHC class II, CD80, CD86), integrins (ITGB3, ITGAV), cytokines (IL-1α, IL-1β, IL-6, IL-2, IL-23p19, IL-12p40), and chemokines (CXCL1, CXCL2). Transcription of the cytokine genes induced by MDP and MSU partially depended on NOD2 but was independent of NLRP3. Finally, we showed that ERK1 and c-JUN activation increased upon MDP and MSU co-stimulation. As a whole, the results indicate that two different NLR activators synergize at the transcriptional level, leading to unique differential expression of genes involved in the innate immune response.
Hydrologic trajectories in transient ground-penetrating-radar reflection data
Authors: Moysey Stephen M.
Published: October 2010

A variable-rate infiltration experiment was conducted in a sandbox to demonstrate that distinctive patterns are produced in transient ground-penetrating-radar (GPR) data collected during wetting and drying events. The observed GPR response was found to be very consistent with the results of numerical simulations performed using finite-difference time-domain modeling of GPR coupled with a 1D unsaturated flow model (HYDRUS-1D) for which the sand hydraulic properties were determined independently using core samples. Despite this agreement, few methods are available that can efficiently analyze transient GPR data to make a quantitative link between observed responses and the hydraulic properties of soils. To address this problem, a computationally efficient method is proposed that is analogous to coherency analysis used in multioffset surveys. The new method isbased on the calculation of semblance along trajectories through transient GPR data. Each trajectory represents a specific GPR arrival, e.g., the ground wave and reflections from the wetting front and subsurface boundaries. The specific path of the trajectories is controlled by the hydraulic properties of the soil, just as the normal-moveout trajectories used to calculate semblance in multioffset data are controlled by wave velocity. Because the method is based on the output of 1D unsaturated flow models, it can be used for situations with complex hydrologic boundary conditions. Good agreement was found in this study between the calculated trajectories and the arrivals observed for both simulated and empirical GPR data. A sensitivity analysis performed in this study suggests that most parameters of the Mualem–van Genuchten soil model can be identified using this approach to coherency analysis of transient GPR data.
Testing the limits of AEM bathymetry with a floating TEM system
Authors: Vrbancich Julian , Fullagar Peter , Smith Richard
Published: October 2010

A floating transient electromagnetic (TEM) system (“sea ring”) simulating a low-altitude helicopter airborne electromagnetic (AEM) system was constructed to test the accuracy of the AEM method for measuring water depth and estimating sediment thickness in shallow coastal waters. A square transmitter loop [Formula: see text], plus concentric inner and outer receiver loops, was strung from masts supported by the circular sea-ring base. Data were stacked over periods from 1 to approximately [Formula: see text] and with loop heights ranging between approximately 5.5 and [Formula: see text] above sea level. The towed sea ring provides a stable platform at a known fixed altitude in calm waters. We have undertaken modeling to investigate the effect of vertical and horizontal displacements of the loops, and to compare circular and square loopgeometries, in proximity to the sea surface. With relatively long stacking times, as long as approximately [Formula: see text], the uncertainty in altitude can be reduced to very low levels. The sea ring has been deployed near Port Lincoln, Australia, in an area with known bathymetry, seawater conductivity [Formula: see text], and sediment thickness (from marine seismic). Initial 1D inversion of raw sea-ring data highlighted significant instrument calibration errors. Empirical correction factors were defined to achieve agreement between measured and modeled TEM responses at selected control points. These corrections were then applied to the entire data set. The 1D inversion of corrected sea-ring data predicted seawater depths within approximately [Formula: see text] of known depths down to [Formula: see text]. These results provide an upper limit to the accuracy that can be expected from airborne EM systems for shallow bathymetry using current technology.
Hydrological consequences of land-cover change: Quantifying the influence of plants on soil moisture with time-lapse electrical resistivity
Authors: Jayawickreme Dushmantha H. , Van Dam Remke L. , Hyndman David W.
Published: October 2010

Electrical resistivity of soils and sediments is strongly influenced by the presence of interstitial water. Taking advantage of this dependency, electrical-resistivity imaging (ERI) can be effectively utilized to estimate subsurface soil-moisture distributions. The ability to obtain spatially extensive data combined with time-lapse measurements provides further opportunities to understand links between land use and climate processes. In natural settings, spatial and temporal changes in temperature and porewater salinity influence the relationship between soil moisture and electrical resistivity. Apart from environmental factors, technical, theoretical, and methodological ambiguities may also interfere with accurate estimation of soil moisture from ERI data. We have examined several of these complicating factors using data from a two-year study at a forest-grassland ecotone, a boundary between neighboring but different plant communities.At this site, temperature variability accounts for approximately 20%–45% of resistivity changes from cold winter to warm summer months. Temporal changes in groundwater conductivity ([Formula: see text]; [Formula: see text]) and a roughly [Formula: see text] spatial difference between the forest and grassland had only a minor influence on the moisture estimates. Significant seasonal fluctuations in temperature and precipitation had negligible influence on the basic measurement errors in data sets. Extracting accurate temporal changes from ERI can be hindered by nonuniqueness of the inversion process and uncertainties related to time-lapse inversion schemes. The accuracy of soil moisture obtained from ERI depends on all of these factors, in addition to empirical parameters that define the petrophysical soil-moisture/resistivity relationship. Many of the complicating factors and modifying variables to accurately quantify soil moisture changes with ERI can be accounted for using field and theoretical principles.
Sensitivity of the high-frequency sounding method to variations in electrical properties
Authors: Wallin Erin L.
Published: October 2010

Instrumentation for high-frequency sounding (HFS) was developed by the U.S. Geological Survey (USGS) in the late 1980s, continuing until 2006. To aid in this development, forward modeling and sensitivity analysis of vertical magnetic fields to electromagnetic (EM) properties between [Formula: see text] and [Formula: see text] were completed. Because these frequencies encompass the transition between the diffusion and propagation regimes, the HFS method ought to be sensitive to all properties contained in the EM wavenumber — namely, electrical conductivity, dielectric permittivity, and magnetic permeability as well as layer thickness. The models consist of three layers that simulate the contam-ination and remediation of dense nonaqueous-phase liquid (DNAPL) contaminants by oxidation. This scenario provides values of [Formula: see text] that would attenuate ground-penetrating radar signals and a range of [Formula: see text] which is a parameter that direct-current resistivity and low-frequency electromagnetic-induction (EMI) techniques are insensitive to. Conductivity and permittivity parameters are calculated with Archie’s law and the Bruggeman-Hanai-Sen (BHS) mixing formula. The importance of thickness and electrical properties to vertical-magnetic-field response of the models initially was addressed using numerical differencing between models containing slight perturbations in electrical properties. Results from this procedure were oscillatory and hence problematic, so analytic partial derivatives of the vertical magnetic field with respect to each parameter were computed for the same scenarios. The derivatives show that the sensitivity to the second-layer permittivity is less than the sensitivity to other properties, and the response is sensitive to slightly magnetic soils. It is also evident that sensitivity and resolution are limited by depth of penetration. The sensitivity curves and plots of the real and imaginary portions of the EM wavenumber demonstrate that propagation begins near [Formula: see text].
GPR characterization of a lacustrine UXO site
Authors: Arcone Steven , Finnegan David , Boitnott Ginger
Published: October 2010

We used [Formula: see text] ground-penetrating-radar (GPR) reflection profiles to determine if high-explosive (HE) depth bombs were possibly detonated within a small New England lake formerly used as a bombing range, as well as the depths and distribution of inert and possibly unexploded ordnance (UXO) within the subbottom sediments. Maximum water depth was [Formula: see text]. The primary munitions were unarmed practice bombs, but terrestrial fragments from HE depth bombs led us to seek stratigraphic obliteration and distortion as evidence of their use. The low water conductivity and quartz-rich sediments provided more than [Formula: see text] of subbottom penetration beneath slope and shelf sediments. The high permittivities of the water and subbottom sediments provided good antenna directivity, excellent 2D migrations, multicentimeter vertical resolution, and a unique pulse waveform signature for metal objects. Our line profiles revealed hundreds of subbottom diffractions, which implied an areal distribution of thou-sands of suspicious objects. Most lay beneath the central basin, but many resided beneath the slopes and shelves as well. Supplementary profiles of a nearby pristine lake and of controlled munitions, a side-scan sonar bottom survey, and time-domain reflectometry dielectric measurements of sediment samples corroborated our findings of natural stratigraphy, a unique metallic diffraction phase signature, the existence of many nonmetallic objects including logs, and subbottom relative permittivities ranging from 28 to 76. The intact natural lacustrine strata, including deltaic foresets and bottom sets, faults, and conformable and unconformable horizons, suggest that live bombs likely did not detonate in the lake. The only stratigraphic disturbances we found were apparent perforations beneath about [Formula: see text] of water, within which diffractions of metallic origin originated. The dielectric results and the prominent slope strata over the deepest horizons led us to conclude that the exceptional subbottom penetration existed under predominantly sandy sediments.
On the estimation of specific surface per unit pore volume from induced polarization: A robust empirical relation fits multiple data sets
Authors: Weller Andreas , Slater Lee , Nordsiek Sven , Ntarlagiannis Dimitrios
Published: October 2010

We analyze the relationship between induced polarization (IP) parameters and the specific surface area normalized to the pore volume [Formula: see text] for an extensive sample database. We find that a single linear imaginary conductivity-[Formula: see text] relation holds across a range of single-frequency IP data sets composed of sandstones and unconsolidated sediments that lack an appreciable metallic mineral content. We also apply a recent approach defined as Debye decomposition (DD) to determine normalized chargeability [Formula: see text], a global estimate of polarization magnitude from available spectral IP (SIP) data sets. A strong linear relationship between [Formula: see text] and [Formula: see text] is also found across multiple data sets. However, SIP model parameters determined for samples containing metallic minerals are approximately two orders of magnitude greater than for the model parameters estimated for the nonmetallic sample database. We propose a concept of “polarizability of the mineral-fluid interface per unit [Formula: see text]” to explain this difference, which is supported by the observed dependence of IP parameters on fluid conductivity between sample types. We suggest that this linear IP-[Formula: see text] relation can be considered the IP equivalent of the classical Archie empirical relation. Whereas the Archie relation describes a power-law relation between electrical conductivity due to electrolytic conduction through the available interconnected pore volume, the IP-[Formula: see text] relation is an equivalent relation between mineral-fluid interfacial polarization and available pore surface area.
Breaks in lithology: Interpretation problems when handling 2D structures with a 1D approximation
Authors: Ley-Cooper Alan Yusen , Macnae James , Viezzoli Andrea
Published: October 2010

Most airborne electromagnetic (AEM) data are processed using successive 1D approximations to produce stitched conductivity-depth sections. Because the current induced in the near surface by an AEM system preferentially circulates at some radial distance from a horizontal loop transmitter (sometimes called the footprint), the section plotted directly below a concentric transmitter-receiver system actually arises from currents induced in the vicinity rather than directly underneath. Detection of paleochannels as conduits for groundwater flow is a common geophysical exploration goal, where locally 2D approximations may be valid for an extinct riverbed or filled valley. Separate from effects of salinity, these paleochannels may be conductive if clay filled or resistive if sand filled and incised into a clay host. Because of the wide system footprint, using stitched 1D approximations or inversions may lead to misleading conductivity-depth images or sections. Near abrupt edges of an extensive conductive layer, the lateral falloff in AEM amplitudes tends to produce a drooping tail in a conductivity section, sometimes coupled with alocal peak where the AEM system is maximally coupled to currents constrained to flow near the conductor edge. Once the width of a conductive ribbon model is less than the system footprint, small amplitudes result, and the source is imaged too deeply in the stitched 1D section. On the other hand, a narrow resistive gap in a conductive layer is incorrectly imaged as a drooping region within the layered conductor; below, the image falsely contains a blocklike poor conductor extending to depth. Additionally, edge-effect responses often are imaged as deep conductors with an inverted horseshoe shape. Incorporating lateral constraints in 1D AEM inversion (LCI) software, designed to improve resolution of continuous layers, more accurately recovers the depth to extensive conductors. The LCI, however, as with any AEM modeling methodology based on 1D forward responses, has limitations in detecting and imaging in the presence of strong 3D lateral discontinuities of dimensions smaller than the annulus of resolution. The isotropic, horizontally slowly varying layered-earth assumption devalues and limits AEM’s 3D detection capabilities. The need for smart, fast algorithms that account for 3D varying electrical properties remains.
How the owl tracks its prey – II
Authors: Takahashi Terry T.
Published: October 2010

Barn owls can capture prey in pitch darkness or by diving into snow, while homing in on the sounds made by their prey. First, the neural mechanisms by which the barn owl localizes a single sound source in an otherwise quiet environment will be explained. The ideas developed for the single source case will then be expanded to environments in which there are multiple sound sources and echoes – environments that are challenging for humans with impaired hearing. Recent controversies regarding the mechanisms of sound localization will be discussed. Finally, the case in which both visual and auditory information are available to the owl will be considered.
The proteomic response of the mussel congenersMytilus galloprovincialisandM. trossulusto acute heat stress: implications for thermal tolerance limits and metabolic costs of thermal stress
Authors: Tomanek Lars , Zuzow Marcus J.
Published: October 2010

The Mediterranean blue mussel, Mytilus galloprovincialis, an invasive species in California, has displaced the more heat-sensitive native congener, Mytilus trossulus, from its former southern range, possibly due to climate change. By comparing the response of their proteomes to acute heat stress we sought to identify responses common to both species as well as differences that account for greater heat tolerance in the invasive. Mussels were acclimated to 13°C for four weeks and exposed to acute heat stress (24°C, 28°C and 32°C) for 1 h and returned to 13°C to recover for 24 h. Using two-dimensional gel electrophoresis and tandem mass spectrometry we identified 47 and 61 distinct proteins that changed abundance in M. galloprovincialis and M. trossulus, respectively. The onset temperatures of greater abundance of some members of the heat shock protein (Hsp) 70 and small Hsp families were lower in M. trossulus. The abundance of proteasome subunits was lower in M. galloprovincialis but greater in M. trossulus in response to heat. Levels of several NADH-metabolizing proteins, possibly linked to the generation of reactive oxygen species (ROS), were lower at 32°C in the cold-adapted M. trossulus whereas proteins generating NADPH, important in ROS defense, were higher in both species. The abundance of oxidative stress proteins was lower at 32°C in M. trossulus only, indicating that its ability to combat heat-induced oxidative stress is limited to lower temperatures. Levels of NAD-dependent deacetylase (sirtuin 5), which are correlated with lifespan, were lower in M. trossulus in response to heat stress. In summary, the expression patterns of proteins involved in molecular chaperoning, proteolysis, energy metabolism, oxidative damage, cytoskeleton and deacetylation revealed a common loci of heat stress in both mussels but also showed a lower sensitivity to high-temperature damage in the warm-adapted M. galloprovincialis, which is consistent with its expanding range in warmer waters.
Dipole source encoding and tracking by the goldfish auditory system
Authors: Coombs Sheryl , Fay Richard R. , Elepfandt Andreas
Published: October 2010

In goldfish and other otophysans, the Weberian ossicles mechanically link the saccule of the inner ear to the anterior swimbladder chamber (ASB). These structures are correlated with enhanced sound-pressure sensitivity and greater sensitivity at high frequencies (600–2000 Hz). However, surprisingly little is known about the potential impact of the ASB on other otolithic organs and about how auditory responses are modulated by discrete sources that change their location or orientation with respect to the ASB. In this study, saccular and lagenar nerve fiber responses and conditioned behaviors of goldfish were measured to a small, low-frequency (50 Hz) vibrating sphere (dipole) source as a function of its location along the body and its orientation with respect to the ASB. Conditioned behaviors and saccular nerve fiber activity exhibited response characteristics nearly identical to those measured from a hydrophone in the same relative position as the ASB. By contrast, response patterns from lagena fibers could not be predicted by pressure inputs to the ASB. Deflation of the ASB abolished the characteristic spatial response pattern of saccular but not lagena fibers. These results show that: (1) the lagena is not driven by ASB-mediated pressure inputs to the ear; (2) the ASB–saccule pathway dominates behavioral responsiveness, operating effectively at frequencies as low as 50 Hz; and (3) behavioral and neural (saccular) responses are strongly modulated by the position and orientation of the dipole with respect to the ASB.
Olfactory morphology and physiology of elasmobranchs
Authors: Meredith Tricia L. , Kajiura Stephen M.
Published: October 2010

Elasmobranch fishes are thought to possess greater olfactory sensitivities than teleost fishes due in part to the large amount of epithelial surface area that comprises their olfactory organs; however, direct evidence correlating the size of the olfactory organ to olfactory sensitivity is lacking. This study examined the olfactory morphology and physiology of five distantly related elasmobranch species. Specifically, we quantified the number of lamellae and lamellar surface area (as if it were a flat sheet, not considering secondary lamellae) that comprise their olfactory organs. We also calculated the olfactory thresholds and relative effectiveness of amino acid odorants for each species. The olfactory organs varied in both the number of lamellae and lamellar surface area, which may be related to their general habitat, but neither correlated with olfactory threshold. Thresholds to amino acid odorants, major olfactory stimuli of all fishes, ranged from 10–9.0 to 10–6.9 mol l–1, which indicates that these elasmobranch species demonstrate comparable thresholds with teleosts. In addition, the relative effectiveness of amino acid stimuli to the olfactory organ of elasmobranchs is similar to that previously described in teleosts with neutral amino acids eliciting significantly greater responses than others. Collectively, these results indicate parallels in olfactory physiology between these two groups of fishes.
Identification and characterization of visual pigments in caecilians (Amphibia: Gymnophiona), an order of limbless vertebrates with rudimentary eyes
Authors: Mohun S. M. , Davies W. L. , Bowmaker J. K. , Pisani D. , Himstedt W. , Gower D. J. , Hunt D. M. , Wilkinson M.
Published: October 2010

In comparison with the other amphibian orders, the Anura (frogs) and Urodela (salamanders), knowledge of the visual system of the snake-like Gymnophiona (caecilians) is relatively sparse. Most caecilians are fossorial with, as far as is known any surface activity occurring mainly at night. They have relatively small, poorly developed eyes and might be expected to possess detectable changes in the spectral sensitivity of their visual pigments. Microspectrophotometry was used to determine the spectral sensitivities of the photoreceptors in three species of caecilian, Rhinatrema bivittatum, Geotrypetes seraphini and Typhlonectes natans. Only rod opsin visual pigment, which may be associated with scotopic (dim light) vision when accompanied by other ‘rod-specific’ components of the phototransduction cascade, was found to be present. Opsin sequences were obtained from the eyes of two species of caecilian, Ichthyophis cf. kohtaoensis and T. natans. These rod opsins were regenerated in vitro with 11-cis retinal to give pigments with spectral sensitivity peaks close to 500 nm. No evidence for cone photoreception, associated with diurnal and colour vision, was detected using molecular and physiological methods. Additionally, visual pigments are short-wavelength shifted in terms of the maximum absorption of light when compared with other amphibian lineages.
Transcriptomic responses to heat stress in invasive and native blue mussels (genusMytilus): molecular correlates of invasive success
Authors: Lockwood Brent L. , Sanders Jon G. , Somero George N.
Published: October 2010

Invasive species are increasingly prevalent in marine ecosystems worldwide. Although many studies have examined the ecological effects of invasives, little is known about the physiological mechanisms that might contribute to invasive success. The mussel Mytilus galloprovincialis, a native of the Mediterranean Sea, is a successful invader on the central and southern coasts of California, where it has largely displaced the native congener, Mytilus trossulus. It has been previously shown that thermal responses of several physiological traits may underlie the capacity of M. galloprovincialis to out-compete M. trossulus in warm habitats. To elucidate possible differences in stress-induced gene expression between these congeners, we developed an oligonucleotide microarray with 8874 probes representing 4488 different genes that recognized mRNAs of both species. In acute heat-stress experiments, 1531 of these genes showed temperature-dependent changes in expression that were highly similar in the two congeners. By contrast, 96 genes showed species-specific responses to heat stress, functionally characterized by their involvement in oxidative stress, proteolysis, energy metabolism, ion transport, cell signaling and cytoskeletal reorganization. The gene that showed the biggest difference between the species was the gene for the molecular chaperone small heat shock protein 24, which was highly induced in M. galloprovincialis and showed only a small change in M. trossulus. These different responses to acute heat stress may help to explain – and predict – the invasive success of M. galloprovincialis in a warming world.
Evolution of anatomical and physiological specialization in the compound eyes of stomatopod crustaceans
Authors: Porter Megan L. , Zhang Yunfei , Desai Shivani , Caldwell Roy L. , Cronin Thomas W.
Published: October 2010

Stomatopod crustaceans have complex and diverse visual systems. Among their many unique features are a specialized ommatidial region (the midband) that enables the eye to have multiple overlapping visual fields, as well as sets of spectral filters that are intercalated at two levels between tiers of photoreceptors involved in polychromatic color vision. Although the physiology and visual function of stomatopod eyes have been studied for many years, how these unique visual features originated and diversified is still an open question. In order to investigate how stomatopods have attained the current complexity in visual function, we have combined physiological and morphological information (e.g. number of midband rows, number of filters in the retina, and the spectral properties of filters) with new phylogenetic analyses of relationships among species based on nucleotide sequence data from two nuclear (18S and 28S rDNA) and two mitochondrial [16S and cytochrome oxidase I (COI)] genes. Based on our recovered phylogenetic relationships among species, we propose two new superfamilies within the Stomatopoda: Hemisquilloidea and Pseudosquillodea. Maximum likelihood ancestral state reconstructions indicate that ancestral stomatopod eyes contained six midband rows and four intrarhabdomal filters, illustrating that the visual physiological complexity originated early in stomatopod evolutionary history. While the two distal filters contain conservative sets of filter pigments, the proximal filters show more spectral diversity in filter types, particularly in midband row 2, and are involved in tuning the color vision system to the photic environment. In particular, a set of related gonodactyloid families (Gonodactylidae, Protosquillidae, Takuidae) inhabiting shallow, brightly lit coral reef waters contain the largest diversity of filter pigments, which are spectrally placed relative to the underlying photoreceptors to take advantage of the broad spectrum of light available in the environment.