bluuebunny/crossref_metadata_2025 huggingface dataset:
Test Cancellation: A College of American Pathologists Q-Probes Study
Authors: Darcy Teresa P. , Barasch Samuel P. , Souers Rhona J. , Perrotta Peter L.
Published: February 2016

Context

Requests for laboratory testing are canceled after a specimen has already been collected from the patient for many reasons. Regardless of the cause, test cancellation represents a significant resource expenditure for laboratories, and many cancellation events impact patient care by delaying the reporting of test results.

Objective

To survey a wide variety of hospitals to determine the rate, causes, and circumstances surrounding laboratory test cancellation events.

Design

Institutions (N = 52) prospectively monitored their test cancellation events during a 6-week period or until 75 cancellation events occurred. Information regarding the test cancellation was recorded, including the primary reason for canceling the test. The rate of test cancellation was calculated based on laboratory specimen volume. Laboratory policies relevant to test cancellation were also surveyed.

Results

A total of 3471 canceled tests were recorded by participating laboratories of 1 118 845 specimens they accessioned, resulting in an aggregate test cancellation rate of 3.1 per 1000 accessions. The most frequently reported reason for test cancellation occurred in the preanalytical phase, and was a duplicate test request, followed by specimen quality reasons including hemolyzed/clotted specimens and insufficient sample quantity for testing. Very few cancellations occurred during the analytical phase of testing. Lower test cancellation rates were reported by larger institutions and by laboratories that received fewer specimens from inpatients.

Conclusions

Cancellation of patient tests after a specimen had been collected and received remains a significant issue for clinical laboratories. Laboratories should monitor causes of test cancellation to identify targets for process improvement efforts and to improve laboratory utilization. Cancellation events due to incomplete identification or poor specimen quality potentially delay patient care. Cancellations due to duplicate orders or excessive frequency of testing represent operational challenges for the laboratory and inefficiency in the health care system. Policies related to test cancellation should be clearly specified and communicated to users of laboratory services.
Implications of the Updated 2013 American Society of Clinical Oncology/College of American Pathologists Guideline Recommendations on Human Epidermal Growth Factor Receptor 2 Gene Testing Using Immunohistochemistry and Fluorescence In Situ Hybridization for Breast Cancer
Authors: Lim Tse Hui , Lim Alvin Soon Tiong , Thike Aye Aye , Tien Sim Leng , Tan Puay Hoon
Published: February 2016

Context

Human epidermal growth factor receptor 2 (HER2/neu) amplification is used as a predictive marker for trastuzumab treatment in breast cancer. Both immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) testing algorithms have been based on the 2007 American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) guidelines. In late 2013, the guidelines were updated with new scoring criteria.

Objective

—To assess the impact of the revised ASCO/CAP recommendations on both IHC and FISH results by using the dual-color HER2/neu and centromeric FISH probes.

Design

Retrospective analysis of 590 invasive carcinomas with concurrent IHC and dual-color HER2/neu and centromeric 17 (CEP17) FISH results, based on 2007 ASCO/CAP guidelines, was conducted from July 2011 to June 2013. With the revised guidelines, patients were recategorized and concordance rates between the 2 assays were recalculated.

Results

—Overall concordance rates for FISH and IHC decreased from 94.9% to 93.8% with reclassification. Negative FISH cases decreased from 79.1% to 69.3%. However, equivocal FISH cases were significantly increased from 0.7% to 9.5%, leading to more retesting. Both positive IHC and FISH cases were also noted to be increased, leading to more patients being eligible for trastuzumab treatment, especially those patients with concurrent HER2/neu and CEP17 polysomy. Approximately 1% of patients with initial FISH negative results were reclassified as having positive results when both the ratios and average copy number of HER2/neu were considered under the revised guidelines.

Conclusions

The revised 2013 ASCO/CAP guidelines can potentially lead to more patients being eligible for trastuzumab therapy but additional retesting is to be expected owing to an increased number of equivocal FISH cases.
Les minorités sexuelles : concepts, prémisses et structure d’une approche clinique
adaptée
Authors: Igartua Karine J. , Montoro Richard
Published: February 2016

Depuis la dépathologisation de l’homosexualité par les sociétés savantes en santé
mentale, la formation des psychothérapeutes sur les minorités sexuelles comporte des
lacunes. On préconise souvent de traiter les patients issus de ces minorités comme tous les
autres. Or, le développement identitaire de ces personnes comporte des particularités qu’il
est nécessaire de connaître pour adapter les évaluations et les interventions
psychothérapeutiques comme il se doit. Le présent article propose un cadre théorique, des
outils d’évaluation et des pistes thérapeutiques pour accompagner une personne issue d’une
minorité sexuelle qui consulte un professionnel en santé mentale.

Les concepts de non-binarité de genre, de construction sociale des rôles de genre,
les dimensions distinctes de l’orientation sexuelle (attirance émotive, attirance physique,
comportement et identité sexuelle), l’indépendance des attirances envers un sexe et envers
l’autre, l’impact et les manifestations de l’homophobie ainsi que le processus identitaire
sont décrits dans le présent article. Une attitude d’ouverture quant à la diaspora sexuelle
est prônée afin d’accueillir le patient et de lui permettre une exploration ouverte dans un
cadre thérapeutique sécurisant et sans danger.

Les différentes facettes à explorer lors de l’évaluation de la sexualité sont
énumérées. Des pistes de traitement psychoéducatif, cognitif et psychodynamique sont
proposées, entre autres : déconstruire les mythes pour réduire l’homophobie ou la
transphobie, panser les blessures narcissiques et relationnelles dues à l’homophobie,
analyser le pour et le contre d’un mode de vie authentique, avec ou sans « sortie du
placard » ou coming out. L’apport des interventions familiales et des thérapies de
groupe est aussi exposé.
Distinguer le processus d’acceptation d’une identité sexuelle minoritaire d’un trouble obsessionnel compulsif avec obsessions sexuelles
Authors: Igartua Karine J.
Published: February 2016

Le processus identitaire par lequel passe une personne d’une minorité sexuelle inclut plusieurs phases, dont la confusion, la prise de conscience d’un homoérotisme, la comparaison avec des pairs hétérosexuels et homosexuels, le deuil des privilèges sociaux reliés à l’hétéronormativité et enfin l’acceptation et l’intégration de son orientation sexuelle minoritaire. Il arrive que la détresse occasionnée par la réalisation d’être autre que ce que l’individu, sa famille et la société avaient prévu amène la personne à consulter un professionnel de la santé. Les pratiques actuelles en cette matière proscrivent toute thérapie de réorientation et encouragent plutôt le professionnel à aider l’individu dans son acceptation de sa minorité sexuelle. Or, il arrive quelques fois que des individus sans aucun homoérotisme consultent pour une détresse reliée à un questionnement identitaire sexuel. Cet article propose une série de cas de jeunes hommes qui ont demandé de l’aide pour accepter leur orientation sexuelle mais qui n’avaient pas l’érotisme pour soutenir leur questionnement pourtant persistant. Le diagnostic de trouble obsessionnel compulsif (TOC) a été posé et traité. Comme il y a peu dans la documentation scientifique décrivant cette forme de TOC, ces illustrations cliniques servent à décrire le phénomène et à dégager quelques pistes diagnostiques et thérapeutiques, et ce, afin d’éviter de confondre le TOC sexuel avec une détresse reliée à la non-acceptation d’un érotisme homosexuel.
Discrimination des minorités sexuelles et de genre au travail : quelles implications pour la santé mentale ?
Authors: Geoffroy Marie , Chamberland Line
Published: February 2016

Malgré les avancées législatives en matière d’égalité au travail pour les minorités sexuelles et de genre (MSG), les données disponibles permettent de constater la persistance des discriminations en milieu de travail envers les personnes lesbiennes, gaies et bisexuelles, et surtout, envers les personnes transsexuelles/transgenres. Cet article, basé sur une revue de la littérature, explore les liens entre les différents vécus de discrimination en milieu de travail et leurs impacts sur la santé mentale chez les MSG et chez différentes sous-populations : hommes ayant des relations sexuelles avec d’autres hommes, femmes non hétérosexuelles, parents lesbiennes et gais, et personnes trans. De plus, l’article explore certains facteurs de protection et de risque individuels et systémiques qui interviennent dans cette relation, entre autres le dévoilement de l’orientation sexuelle ou de l’identité de genre et le soutien organisationnel. Finalement, la littérature sur la discrimination en milieu de travail et la santé mentale des MSG met en lumière l’importance, dans le contexte actuel, des approches intersectionnelles et des études sur les micro-agressions. Pour terminer, l’article discute les implications pour les milieux de pratique, de recherche et de travail tout en formulant plusieurs recommandations.
Adaptation et neurosciences I : craintes, société, méthodologie, finalité
Authors: Desseilles Martin
Published: February 2016

Cet article est le premier de deux articles explorant les liens bidirectionnels entre le concept d’adaptation et celui de neurosciences. Nous verrons tout d’abord dans cet article que les neurosciences peuvent être perçues comme ambitieuses et toutes-puissantes oscillant entre un danger réductionniste et déshumanisant ou bien cristallisant certains fantasmes de maîtrise. Nous verrons ensuite que la société s’adapte aux neurosciences en intégrant certaines méthodologies et certaines découvertes dans des domaines très variés, au point que nous pouvons nous questionner sur la neurosociété de demain. Ensuite nous verrons que la méthodologie des neurosciences est elle-même fréquemment remise en question et nécessite que chacun en connaisse les limites sans s’en tenir aux seules promesses. Après cela, nous verrons que l’adaptation vue comme une promesse d’un but déterminé et fini peut s’avérer rassurante mais est surtout improbable.
Perspective biopsychologique systémique des émotions de base1
Authors: Poisson Benoît
Published: February 2016

La perspective biopsychologique systémique des émotions de base est un modèle heuristique permettant de mieux comprendre comment l’individu apprend à s’adapter à son environnement grâce aux différentes émotions qui se sont développées progressivement en même temps que la myélinisation des circuits neurohormonaux, de la naissance jusqu’à environ vingt et un ans. Ce sont ces mêmes émotions, agissant en complémentarité, qui vont permettre à l’individu de maintenir son équilibre tout au long de sa vie.

Cinq émotions de base ont été retenues, car dans la documentation scientifique, cinq circuits neuronaux associés aux émotions sont définis, soit les cinq circuits décrits par Panksepp : celui de l’agressivité (rage-colère), celui du stress (peur-surprise), développé par LeDoux, celui de la récompense (recherche-joie), développé par Tassin, celui de l’empathie (panique-tristesse), développé par Decety, et celui de la conscience (conscience-bonheur), développé par Damasio.
L’enfant borderline en devenir II : validation préliminaire de l’Échelle de traits de personnalité limite pour enfants
Authors: Dubé Geneviève , Terradas Miguel M. , Arsenault Sophie
Published: February 2016

Le trouble de personnalité limite (TPL) est une psychopathologie sévère qui engendre une grande détresse personnelle et familiale et dont l’étiologie remonte à l’enfance. Les données empiriques appuyant une certaine stabilité temporelle des traits de personnalité de l’enfance à l’adolescence et à l’âge adulte, plusieurs auteurs soutiennent qu’il est possible d’observer chez des enfants et des adolescents des traits de personnalité pouvant être associés aux caractéristiques du TPL à l’âge adulte. Peu d’instruments permettent toutefois d’identifier chez les enfants et les adolescents des traits associés au TPL, d’où l’intérêt du Borderline Personality Features Scale for Children (BPFS-C). Basé sur une perspective développementale, cet instrument mesure les traits de personnalité limite chez les enfants de neuf ans et plus par un questionnaire autorapporté. Une première étude de validation de la version française de l’instrument démontre une cohérence interne très satisfaisante. Les corrélations entre les deux versions de l’instrument (en anglais et en français) sont significatives. L’analyse en composantes principales révèle un modèle en quatre composantes qui présente des similarités avec les quatre sous-échelles de la version anglaise, mais diffère quant à la répartition des énoncés appartenant initialement à la sous-échelle « problèmes d’identité » du BPFS-C. La poursuite de la validation de cet instrument permettrait d’identifier des traits de personnalité et des comportements associés au développement du TPL dans l’enfance et favoriserait la réalisation d’études prospectives afin d’augmenter les connaissances sur l’étiologie du TPL, ses manifestations et sa trajectoire au cours du développement.
Selectively driving cholinergic fibers optically in the thalamic reticular nucleus promotes sleep
Authors: Ni Kun-Ming , Hou Xiao-Jun , Yang Ci-Hang , Dong Ping , Li Yue , Zhang Ying , Jiang Ping , Berg Darwin K , Duan Shumin , Li Xiao-Ming
Published: February 2016

Cholinergic projections from the basal forebrain and brainstem are thought to play important roles in rapid eye movement (REM) sleep and arousal. Using transgenic mice in which channelrhdopsin-2 is selectively expressed in cholinergic neurons, we show that optical stimulation of cholinergic inputs to the thalamic reticular nucleus (TRN) activates local GABAergic neurons to promote sleep and protect non-rapid eye movement (NREM) sleep. It does not affect REM sleep. Instead, direct activation of cholinergic input to the TRN shortens the time to sleep onset and generates spindle oscillations that correlate with NREM sleep. It does so by evoking excitatory postsynaptic currents via α7-containing nicotinic acetylcholine receptors and inducing bursts of action potentials in local GABAergic neurons. These findings stand in sharp contrast to previous reports of cholinergic activity driving arousal. Our results provide new insight into the mechanisms controlling sleep.
Identity of neocortical layer 4 neurons is specified through correct positioning into the cortex
Authors: Oishi Koji , Nakagawa Nao , Tachikawa Kashiko , Sasaki Shinji , Aramaki Michihiko , Hirano Shinji , Yamamoto Nobuhiko , Yoshimura Yumiko , Nakajima Kazunori
Published: February 2016

Many cell-intrinsic mechanisms have been shown to regulate neuronal subtype specification in the mammalian neocortex. However, how much cell environment is crucial for subtype determination still remained unclear. Here, we show that knockdown of Protocadherin20 (Pcdh20), which is expressed in post-migratory neurons of layer 4 (L4) lineage, caused the cells to localize in L2/3. The ectopically positioned “future L4 neurons” lost their L4 characteristics but acquired L2/3 characteristics. Knockdown of a cytoskeletal protein in the future L4 neurons, which caused random disruption of positioning, also showed that those accidentally located in L4 acquired the L4 characteristics. Moreover, restoration of positioning of the Pcdh20-knockdown neurons into L4 rescued the specification failure. We further suggest that the thalamocortical axons provide a positional cue to specify L4 identity. These results suggest that the L4 identity is not completely determined at the time of birth but ensured by the surrounding environment after appropriate positioning.
Membrane palmitoylated protein 2 is a synaptic scaffold protein required for synaptic SK2-containing channel function
Authors: Kim Gukhan , Luján Rafael , Schwenk Jochen , Kelley Melissa H , Aguado Carolina , Watanabe Masahiko , Fakler Bernd , Maylie James , Adelman John P
Published: February 2016

Mouse CA1 pyramidal neurons express apamin-sensitive SK2-containing channels in the post-synaptic membrane, positioned close to NMDA-type (N-methyl-D-aspartate) glutamate receptors. Activated by synaptically evoked NMDAR-dependent Ca2+ influx, the synaptic SK2-containing channels modulate excitatory post-synaptic responses and the induction of synaptic plasticity. In addition, their activity- and protein kinase A-dependent trafficking contributes to expression of long-term potentiation (LTP). We have identified a novel synaptic scaffold, MPP2 (membrane palmitoylated protein 2; p55), a member of the membrane-associated guanylate kinase (MAGUK) family that interacts with SK2-containing channels. MPP2 and SK2 co-immunopurified from mouse brain, and co-immunoprecipitated when they were co-expressed in HEK293 cells. MPP2 is highly expressed in the post-synaptic density of dendritic spines on CA1 pyramidal neurons. Knocking down MPP2 expression selectively abolished the SK2-containing channel contribution to synaptic responses and decreased LTP. Thus, MPP2 is a novel synaptic scaffold that is required for proper synaptic localization and function of SK2-containing channels.
An external sodium ion binding site controls allosteric gating in TRPV1 channels
Authors: Jara-Oseguera Andres , Bae Chanhyung , Swartz Kenton J
Published: February 2016

TRPV1 channels in sensory neurons are integrators of painful stimuli and heat, yet how they integrate diverse stimuli and sense temperature remains elusive. Here, we show that external sodium ions stabilize the TRPV1 channel in a closed state, such that removing the external ion leads to channel activation. In studying the underlying mechanism, we find that the temperature sensors in TRPV1 activate in two steps to favor opening, and that the binding of sodium to an extracellular site exerts allosteric control over temperature-sensor activation and opening of the pore. The binding of a tarantula toxin to the external pore also exerts control over temperature-sensor activation, whereas binding of vanilloids influences temperature-sensitivity by largely affecting the open/closed equilibrium. Our results reveal a fundamental role of the external pore in the allosteric control of TRPV1 channel gating and provide essential constraints for understanding how these channels can be tuned by diverse stimuli.
Optical correlation-domain reflectometry without optical frequency shifter
Authors: Shizuka Makoto , Shimada Shumpei , Hayashi Neisei , Mizuno Yosuke , Nakamura Kentaro
Published: February 2016

To achieve distributed reflectivity measurements along an optical fiber, we developed a simplified cost-effective configuration for optical correlation- (or coherence-) domain reflectometry based on a synthesized optical coherence function using sinusoidal modulation. By excluding the conventional optical heterodyne detection that accompanies the frequency shift (without using an acousto-optic modulator) and by exploiting the foot of the electrical Fresnel reflection spectrum, the electrical bandwidth required for signal processing is lowered to several megahertz. We evaluate the basic system performance and demonstrate its high-speed operation (10 ms for one scan) by tracking a moving reflection point in real time.
High-peak-power subnanosecond pulse characteristics in a doubly Q-switched and mode-locking green laser with electro-optic modulator and Cr4+:YAG
Authors: Tang Wenjing , Zhao Jia , Yang Kejian , Zhao Shengzhi , Li Guiqiu , Li Dechun , Li Tao , Qiao Wenchao
Published: February 2016

By simultaneously employing an electro-optic (EO) modulator and Cr4+:YAG in a dual-loss-modulated Q-switched and mode-locking (QML) Nd:Lu0.15Y0.85VO4/KTP green laser, a subnanosecond single mode-locking (ML) green pulse with high peak power underneath a Q-switched envelope is obtained. Three Cr4+:YAG absorbers with different initial transmissions are used in the experiment. The pulse characteristics versus incident pump power under different initial transmissions and modulation frequencies are measured. The shortest pulse duration of 349 ps is obtained with a pulse energy as high as 371 µJ, corresponding to a peak power of 1.063 MW.
The 16S rRNA gene in the study of marine microbial communities
Authors: Valenzuela-González Fabiola , Casillas-Hernández Ramón , Villalpando Enrique , Vargas-Albores Francisco
Published: February 2016

New sequencing technologies and analytical capabilities have stimulated the study of microbial communities from specific environments, enabling researchers to understand the complexity of those systems. The 16S rRNA gene has proved very useful in describing the diversity and characterization of marine microbial communities, particularly of uncultivated organisms. The development of new sequencing techniques has contributed to the exponential increase in the number of reported 16S rRNA sequences as barcodes for microorganisms, forcing a review of concepts and methods for the taxonomic classification of these organisms. Manipulation and analysis of large amounts of genetic information have prompted the development of specific databases, specialized algorithms, and computational tools to compare thousands of such sequences and make a taxonomic assignment. Complete 16S rRNA sequences are thus needed for accurate and reproducible taxonomy assignment in the study of marine bacterial communities.
Effects of ocean climate on life cycles and distribution of small pelagic fishes in the California Current System off Baja California
Authors: Valencia-Gasti José Augusto , Baumgartner Timothy , Durazo Reginaldo
Published: February 2016

Due to their sensitivity to climate forcing that may alter their abundance and distribution, small pelagic fish are important ecological indicators of the state of the California Current System. They are schooling, planktivorous fish that provide forage for higher trophic levels. We describe the life cycle histories and patterns of distribution of sardine, anchovy, and mackerel species occupying the waters along the west coast of the Baja California Peninsula (Mexico). The links between the physical and biological forcing and the structure and condition of their habitats, their patterns of movement, productivity, and stock structure (where information is available) are described in relation to the fisheries. We have used the catches as a proxy for the history of the different stocks, while recognizing that fisheries-derived information is biased by the operational scale and only covers areas where fish are available. We have relied mainly on studies of sardines to evaluate the validity of the principal paradigms in fisheries oceanography. We describe how the environment can structure a population by relating an example given by the spatiotemporal variability of the northern and southern stocks of Pacific sardine (Sardinops sagax) and Pacific mackerel (Scomber japonicus) from 2000 to 2014. During this period, the northern stocks showed a marked tendency to contract southwards, as far south as Magdalena Bay, in response to the regional cooling that began in the previous decade. It appears that the combined effects of fishing and climate change may sufficiently alter habitat characteristics so that both the distribution and productivity of a population are shifted.
Multiple sources of soluble atmospheric iron to Antarctic waters
Authors: Winton V. H. L. , Edwards R. , Delmonte B. , Ellis A. , Andersson P. S. , Bowie A. , Bertler N. A. N. , Neff P. , Tuohy A.
Published: February 2016

The Ross Sea, Antarctica, is a highly productive region of the Southern Ocean. Significant new sources of iron (Fe) are required to sustain phytoplankton blooms in the austral summer. Atmospheric deposition is one potential source. The fractional solubility of Fe is an important variable determining Fe availability for biological uptake. To constrain aerosol Fe inputs to the Ross Sea region, fractional solubility of Fe was analyzed in a snow pit from Roosevelt Island, eastern Ross Sea. In addition, aluminum, dust, and refractory black carbon (rBC) concentrations were analyzed, to determine the contribution of mineral dust and combustion sources to the supply of aerosol Fe. We estimate exceptionally high dissolved Fe (dFe) flux of 1.2 × 10−6 g m−2 y−1 and total dissolvable Fe flux of 140 × 10−6 g m−2 y−1 for 2011/2012. Deposition of dust, Fe, Al, and rBC occurs primarily during spring‐summer. The observed background fractional Fe solubility of ~0.7% is consistent with a mineral dust source. Radiogenic isotopic ratios and particle size distribution of dust indicates that the site is influenced by local and remote sources. In 2011/2012 summer, relatively high dFe concentrations paralleled both mineral dust and rBC deposition. Around half of the annual aerosol Fe deposition occurred in the austral summer phytoplankton growth season; however, the fractional Fe solubility was low. Our results suggest that the seasonality of dFe deposition can vary and should be considered on longer glacial‐interglacial timescales.
Contribution of regional sources to atmospheric methane over the Amazon Basin in 2010 and 2011
Authors: Wilson Chris , Gloor Manuel , Gatti Luciana V. , Miller John B. , Monks Sarah A. , McNorton Joey , Bloom A. Anthony , Basso Luana S. , Chipperfield Martyn P.
Published: February 2016

We present an assessment of methane (CH4) atmospheric concentrations over the Amazon Basin for 2010 and 2011 using a 3‐D atmospheric chemical transport model, two wetland emission models, and new observations made during biweekly flights made over four locations within the basin. We attempt to constrain basin‐wide CH4 emissions using the observations, and since 2010 was an unusually dry year, we assess the effect of this drought on Amazonian methane emissions. We find that South American emissions contribute up to 150 ppb to concentrations at the sites, mainly originating from within the basin. Our atmospheric model simulations agree reasonably well with measurements at three of the locations (0.28 ≤ r2 ≤ 0.63, mean bias ≤ 9.5 ppb). Attempts to improve the simulated background CH4 concentration through analysis of simulated and observed sulphur hexafluoride concentrations do not improve the model performance, however. Through minimisation of seasonal biases between the simulated and observed atmospheric concentrations, we scale our prior emission inventories to derive total basin‐wide methane emissions of 36.5–41.1 Tg(CH4)/yr in 2010 and 31.6–38.8 Tg(CH4)/yr in 2011. These totals suggest that the Amazon contributes significantly (up to 7%) to global CH4 emissions. Our analysis indicates that factors other than precipitation, such as temperature variations or tree mortality, may have affected microbial emission rates. However, given the uncertainty of our emission estimates, we cannot say definitively whether the noncombustion emissions from the region were different in 2010 and 2011, despite contrasting meteorological conditions between the two years.
Modeled temperatures and fluid source distributions for the Mexican subduction zone: Effects of hydrothermal circulation and implications for plate boundary seismic processes
Authors: Perry Matthew , Spinelli Glenn A. , Wada Ikuko , He Jiangheng
Published: February 2016

In subduction zones, spatial variations in pore fluid pressure are hypothesized to control the sliding behavior of the plate boundary fault. The pressure‐temperature paths for subducting material control the distributions of dehydration reactions, a primary control on the pore fluid pressure distribution. Thus, constraining subduction zone temperatures are required to understand the seismic processes along the plate interface. We present thermal models for three margin‐perpendicular transects in the Mexican subduction zone. We examine the potential thermal effects of vigorous fluid circulation in a high‐permeability aquifer within the basaltic basement of the oceanic crust and compare the results with models that invoke extremely high pore fluid pressures to reduce frictional heating along the megathrust. We combine thermal model results with petrological models to determine the spatial distribution of fluid release from the subducting slab and compare dewatering locations with the locations of seismicity, nonvolcanic tremor, slow‐slip events, and low‐frequency earthquakes. Simulations including hydrothermal circulation are most consistent with surface heat flux measurements. Hydrothermal circulation has a maximum cooling effect of 180°C. Hydrothermally cooled crust carries water deeper into the subduction zone; fluid release distributions in these models are most consistent with existing geophysical data. Our models predict focused fluid release, which could generate overpressures, coincident with an observed ultraslow layer (USL) and a region of nonvolcanic tremor. Landward of USLs, a downdip decrease in fluid source magnitude could result in the dissipation in overpressure in the oceanic crust without requiring a downdip increase in fault zone permeability, as posited in previous studies.
Multiscale seismic heterogeneity in the continental lithosphere
Authors: Kennett B. L. N. , Furumura T.
Published: February 2016

We examine the nature of seismic heterogeneity in the continental lithosphere, with particular reference to Australia. With the inclusion of deterministic large‐scale structure and realistic medium‐scale features, there is not a need for strong fine‐scale variations. The resulting multiscale heterogeneity model gives a good representation of the character of observed seismograms and their geographic variation, and is also in good agreement with recent direct results on P wave reflectivity in the lithosphere. Fine‐scale heterogeneity is pervasive, but strongest in the crust. There is a weak quasi‐laminar component above the lithosphere‐asthenosphere transition with horizontal correlation length of 10 km and vertical correlation length of 0.5 km. Within the transition, the aspect ratio of heterogeneity changes and can be well represented with a horizontal correlation length of 5 km and vertical correlation length of 1 km. For the Australian cratons, this transition zone needs low intrinsic attenuation (high Q) to sustain the long high‐frequency coda of both P and S waves. The interaction of the different aspects of the heterogeneity is complex and produces a diversity of behavior depending on the relative thickness of the different lithospheric zones. The multiscale model reconciles many of the divergent concepts of the character of heterogeneity based on interpretations of particular aspects of the seismic wavefield. The varying nature of the heterogeneity also ties well with the variations in tectonic character across the Australian continent.
Ocean calibration approach for data from the GRACE Follow‐On mission
Authors: Bender Peter L. , Betts Casey R.
Published: February 2016

The Gravity Recovery and Climate Experiment (GRACE) mission has been providing valuable new information on time variations in the Earth's gravity field since 2002. In addition, the GRACE Follow‐On mission is scheduled to be flown soon after the end of life of the GRACE mission in order to minimize the loss of valuable data on the Earth's gravity field changes. In view of the major benefits to hydrology and oceanography, as well as to other fields, it is desirable to investigate the fundamental limits to monitoring the time variations in the Earth's gravity field during GRACE‐type missions. A simplified model is presented in this paper for making estimates of the effect of differential spurious accelerations of the satellites during times when four successive revolutions cross the Pacific Ocean. The analysis approach discussed is to make use of changes in the satellite separation observed during passages across low‐latitude regions of the Pacific and of other oceans to correct for spurious accelerations of the satellites. The low‐latitude regions of the Pacific and of other oceans are the extended regions where the a priori uncertainties in the time variations of the geopotential heights due to mass distribution changes are known best. In addition, advantage can be taken of the repeated crossings of the South Pole and the North Pole, since the uncertainties in changes in the geopotential heights at the poles during the time required for four orbit revolutions are likely to be small.
Investigation of earthquake jump distance for strike‐slip step overs based on 3‐D dynamic rupture simulations in an elastic half‐space
Authors: Hu Feng , Zhang Zhenguo , Chen Xiaofei
Published: February 2016

We systematically investigate the distance that dynamically propagating earthquake ruptures could jump across step overs in strike‐slip faults set in a homogeneous half‐space. The following factors are found to have major effects on the critical jump distance: the dimensionless effective shear stress, the initial normal stress, the Earth's free surface, and the accelerating length of the rupture front on the main fault prior to a jump. An important finding in this study is that the critical jump distance for extensional step overs could exceed 10 km under certain conditions, while ruptures on compressional step overs under the same conditions could only jump 6 km fault step overs. This may provide a physical explanation for some geological observations of over 10 km jump distance in natural earthquake. The critical jump distance usually increases as the dimensionless effective shear stress increases. Without the free surface effect, the critical jump distance for step overs could only reach up to 6 km, which is very close to the 5 km given by the classic 2‐D simulations.
Riverine skin temperature response to subsurface processes in low wind speeds
Authors: Brumer Sophia E. , Zappa Christopher J. , Anderson Steven P. , Dugan John P.
Published: February 2016

Both surface and subsurface processes modulate the surface thermal skin and as such the skin temperature may serve as an indicator for coastal, estuarine, and alluvial processes. Infrared (IR) imagery offers the unique tool to survey such systems, allowing not only to assess temperature variability of the thermal boundary layer, but also to derive surface flow fields through digital particle image velocimetry, optical flow techniques, or spectral methods. In this study, IR time‐series imagery taken from a boat moored in the Hudson River estuary is used to determine surface flow, turbulent kinetic energy dissipation rate, and characteristic temperature and velocity length scales. These are linked to subsurface measurements provided by in situ instruments. Under the low wind conditions and weak stratification, surface currents and dissipation rate are found to reflect subsurface mean flow (r2 = 0.89) and turbulence (r2 = 0.75). For relatively low dissipation rates, better correlations are obtained by computing dissipation rates directly from wavenumber spectra rather than when having to assume the validity of the Taylor hypothesis. Furthermore, the subsurface dissipation rate scales with the surface length scales (L) and mean flow (U) using
(r2 = 0.9). The surface length scale derived from the thermal fields is found to have a strong linear relationship (r2 = 0.88) to water depth (D) with (D/L) ∼ 13. Such a relation may prove useful for remote bathymetric surveys when no waves are present.
The distribution of glacial meltwater in the Amundsen Sea, Antarctica, revealed by dissolved helium and neon
Authors: Kim Intae , Hahm Doshik , Rhee Tae Siek , Kim Tae Wan , Kim Chang‐Sin , Lee SangHoon
Published: February 2016

The light noble gases, helium (He) and neon (Ne), dissolved in seawater, can be useful tracers of freshwater input from glacial melting because the dissolution of air bubbles trapped in glacial ice results in an approximately tenfold supersaturation. Using He and Ne measurements, we determined, for the first time, the distribution of glacial meltwater (GMW) within the water columns of the Dotson Trough (DT) and in front of the Dotson and Getz Ice Shelves (DIS and GIS, respectively) in the western Amundsen Sea, Antarctica, in the austral summers of 2011 and 2012. The measured saturation anomalies of He and Ne (ΔHe and ΔNe) were in the range of 3–35% and 2–12%, respectively, indicating a significant presence of GMW. Throughout the DT, the highest values of ΔHe (21%) were observed at depths of 400–500 m, corresponding to the layer between the incoming warm Circumpolar Deep Water and the overlying Winter Water. The high ΔHe (and ΔNe) area extended outside of the shelf break, suggesting that GMW is transported more than 300 km offshore. The ΔHe was substantially higher in front of the DIS than the GIS, and the highest ΔHe (31%) was observed in the western part of the DIS, where concentrated outflow from the shelf to the offshore was observed. In 2012, the calculated GMW fraction in seawater based on excess He and Ne decreased by 30–40% compared with that in 2011 in both ice shelves, indicating strong temporal variability in glacial melting.
Meteorological factors contributing to the interannual variability of midsummer surface ozone in Colorado, Utah, and other western U.S. states
Authors: Reddy Patrick J. , Pfister Gabriele G.
Published: February 2016

We use daily maximum 8 h average surface O3 concentrations (MDA8) for July 1995–2013, meteorological variables from the National Center for Environmental Prediction/National Center for Atmospheric Research Reanalysis, the North American Regional Reanalysis, and output from regional chemistry‐climate simulations to assess relationships between O3 and weather in the western U.S. We also explore relationships among July O3, satellite‐derived NO2, and meteorology. A primary objective of this study is to identify an effective method for correcting the effects of meteorology on July MDA8. We find significant correlations between July MDA8 O3 and meteorological variables for sites in or near Denver, Colorado, and Salt Lake City, Utah. The highest correlations were for 500 hPa heights, surface temperatures, and 700 hPa temperatures and zonal winds. We conclude that increased 500 hPa heights lead to high July O3 in much of the western U.S., particularly in areas of elevated terrain near urban sources of NO2 and other O3 precursors. In addition to bringing warmer temperatures and fewer clouds, upper level ridges decrease winds and allow cyclic terrain‐driven circulations to reduce transport away from sources. Because of strong, nearly linear responses of July MDA8 to 500 hPa heights, it is not reasonable to use uncorrected trends in peak O3 for assessments of the effectiveness of emissions controls for much of the western U.S. Robust linear regressions for July MDA8 and tropospheric NO2 with 500 hPa heights can be used to assess and correct trends in July MDA8 in the Intermountain West.
Effect of dimethylamine on the gas phase sulfuric acid concentration measured by Chemical Ionization Mass Spectrometry
Authors: Rondo L. , Ehrhart S. , Kürten A. , Adamov A. , Bianchi F. , Breitenlechner M. , Duplissy J. , Franchin A. , Dommen J. , Donahue N. M. , Dunne E. M. , Flagan R. C. , Hakala J. , Hansel A. , Keskinen H. , Kim J. , Jokinen T. , Lehtipalo K. , Leiminger M. , Praplan A. , Riccobono F. , Rissanen M. P. , Sarnela N. , Schobesberger S. , Simon M. , Sipilä M. , Smith J. N. , Tomé A. , Tröstl J. , Tsagkogeorgas G. , Vaattovaara P. , Winkler P. M. , Williamson C. , Wimmer D. , Baltensperger U. , Kirkby J. , Kulmala M. , Petäjä T. , Worsnop D. R. , Curtius J.
Published: February 2016

Sulfuric acid is widely recognized as a very important substance driving atmospheric aerosol nucleation. Based on quantum chemical calculations it has been suggested that the quantitative detection of gas phase sulfuric acid (H2SO4) by use of Chemical Ionization Mass Spectrometry (CIMS) could be biased in the presence of gas phase amines such as dimethylamine (DMA). An experiment (CLOUD7 campaign) was set up at the CLOUD (Cosmics Leaving OUtdoor Droplets) chamber to investigate the quantitative detection of H2SO4 in the presence of dimethylamine by CIMS at atmospherically relevant concentrations. For the first time in the CLOUD experiment, the monomer sulfuric acid concentration was measured by a CIMS and by two CI‐APi‐TOF (Chemical Ionization‐Atmospheric Pressure interface‐Time Of Flight) mass spectrometers. In addition, neutral sulfuric acid clusters were measured with the CI‐APi‐TOFs. The CLOUD7 measurements show that in the presence of dimethylamine (<5 to 70 pptv) the sulfuric acid monomer measured by the CIMS represents only a fraction of the total H2SO4, contained in the monomer and the clusters that is available for particle growth. Although it was found that the addition of dimethylamine dramatically changes the H2SO4 cluster distribution compared to binary (H2SO4‐H2O) conditions, the CIMS detection efficiency does not seem to depend substantially on whether an individual H2SO4 monomer is clustered with a DMA molecule. The experimental observations are supported by numerical simulations based on A Self‐contained Atmospheric chemistry coDe coupled with a molecular process model (Sulfuric Acid Water NUCleation) operated in the kinetic limit.
Emulation and Sobol' sensitivity analysis of an atmospheric dispersion model applied to the Fukushima nuclear accident
Authors: Girard Sylvain , Mallet Vivien , Korsakissok Irène , Mathieu Anne
Published: February 2016

Simulations of the atmospheric dispersion of radionuclides involve large uncertainties originating from the limited knowledge of meteorological input data, composition, amount and timing of emissions, and some model parameters. The estimation of these uncertainties is an essential complement to modeling for decision making in case of an accidental release. We have studied the relative influence of a set of uncertain inputs on several outputs from the Eulerian model Polyphemus/Polair3D on the Fukushima case. We chose to use the variance‐based sensitivity analysis method of Sobol'. This method requires a large number of model evaluations which was not achievable directly due to the high computational cost of Polyphemus/Polair3D. To circumvent this issue, we built a mathematical approximation of the model using Gaussian process emulation. We observed that aggregated outputs are mainly driven by the amount of emitted radionuclides, while local outputs are mostly sensitive to wind perturbations. The release height is notably influential, but only in the vicinity of the source. Finally, averaging either spatially or temporally tends to cancel out interactions between uncertain inputs.
Topographically mediated ice stream subglacial drainage networks
Authors: Hiester J. , Sergienko O. V. , Hulbe C. L.
Published: February 2016

Satellite laser altimetry reveals short timescale changes in Antarctic ice sheet surface elevation that are suggested to be driven by subglacial water transport and storage. Here details of the interaction between the dynamics of ice stream flow, subglacial water system, and bed elevation relief are examined in the context of idealized, heterogeneous bed geometries. Using a two‐way coupled model of ice and subglacial water flow, we show that basal topography controls the temporal and spatial variability of the sub–ice stream hydraulic system. The orientation and characteristic dimensions of the topographic undulations determine the morphology (connected subglacial ponds or channel‐like subglacial water features) and timescales of the sub–ice stream drainage system. The short‐term (several years to decades) variability of the simulated coupled ice stream/subglacial water system suggests that the short‐term surface variations detected in remote sensing observations may be indicative of a rapidly evolving subglacial water system. Our simulations also show that interaction between ice flow and the highly dynamic subglacial water system has a strong effect on effective stress in the ice. Large effective stress magnitudes arise over areas where the basal traction is characterized by strong spatial gradients, that is, transitions from high to low basal traction or vise versa. These transitions migrate on multiyear timescales and thus cause large effective stress variability on the same temporal scales.
Matrix association effects on hydrodynamic sorting and degradation of terrestrial organic matter during cross‐shelf transport in the Laptev and East Siberian shelf seas
Authors: Tesi Tommaso , Semiletov Igor , Dudarev Oleg , Andersson August , Gustafsson Örjan
Published: February 2016

This study seeks an improved understanding of how matrix association affects the redistribution and degradation of terrigenous organic carbon (TerrOC) during cross‐shelf transport in the Siberian margin. Sediments were collected at increasing distance from two river outlets (Lena and Kolyma Rivers) and one coastal region affected by erosion. Samples were fractionated according to density, size, and settling velocity. The chemical composition in each fraction was characterized using elemental analyses and terrigenous biomarkers. In addition, a dual‐carbon‐isotope mixing model (δ13C and Δ14C) was used to quantify the relative TerrOC contributions from active layer (Topsoil) and Pleistocene Ice Complex Deposits (ICD). Results indicate that physical properties of particles exert first‐order control on the redistribution of different TerrOC pools. Because of its coarse nature, plant debris is hydraulically retained in the coastal region. With increasing distance from the coast, the OC is mainly associated with fine/ultrafine mineral particles. Furthermore, biomarkers indicate that the selective transport of fine‐grained sediment results in mobilizing high‐molecular weight (HMW) lipid‐rich, diagenetically altered TerrOC while lignin‐rich, less degraded TerrOC is retained near the coast. The loading (µg/m2) of lignin and HMW wax lipids on the fine/ultrafine fraction drastically decreases with increasing distance from the coast (98% and 90%, respectively), which indicates extensive degradation during cross‐shelf transport. Topsoil‐C degrades more readily (90 ± 3.5%) compared to the ICD‐C (60 ± 11%) during transport. Altogether, our results indicate that TerrOC is highly reactive and its accelerated remobilization from thawing permafrost followed by cross‐shelf transport will likely represent a positive feedback to climate warming.