bluuebunny/crossref_metadata_2025 huggingface dataset:
Correlations Between the Biochemistry and Mechanical States of a Sea-Urchin Ligament: A Mutable Collagenous Structure
Authors: Ribeiro A. R. , Barbaglio A. , Oliveira M. J. , Santos R. , Coelho A. V. , Ribeiro C. C. , Wilkie I. C. , Carnevali M. D. Candia , Barbosa M. A.
Published: June 2012

Mutable collagenous tissues (MCTs) of echinoderms can be regarded as intelligent and dynamic biomaterials, due to their ability to reversibly change their mechanical properties in a short physiological time span. This mutability phenomenon is nervously mediated and involves secreted factors of the specialized ‘juxtaligamental’ cells, which, when released into the extracellular matrix (ECM), change the cohesive forces between collagen fibrils. MCTs exist in nature in several forms, including some associated with echinoderm autotomy mechanisms. Since the molecular mechanism of mutability is still incompletely understood, the aim of this work was to provide a detailed biochemical analysis of a typical mutable collagenous structure and to identify possible correlations between its biochemistry and mechanical states. A better understanding of the mutability phenomena is likely to provide a unique opportunity to develop new concepts that can be applied in the design of dynamic biomaterial for tissue regeneration, leading to new strategies in regenerative medicine. The MCT model used was the compass depressor ligament (CDL) of a sea urchin (Paracentrotus lividus), which was analyzed in different mechanical states, mimicking the mutability phenomenon. Spectroscopic techniques, namely Fourier transform infrared (FT-IR) and confocal Raman microscopy, were used to identify the specific molecular components that contribute to the CDL biochemical microenvironment and to investigate the possibility that remodelling/synthesis of new ECM components occurs during the mutability phenomenon by analogy with events during pregnancy in the uterine cervix of mammals (which also consists mainly of mechanically adaptable connective tissues). The results demonstrate that CDL ECM includes collagen with biochemical similarities to mammalian type I collagen, as well as sulphated glycosaminoglycans (GAGs). CDL mutability seems to involve a molecular rearrangement of the ECM, without synthesis of new ECM components. Although there were no significant biochemical differences between CDLs in the various mechanical states were observed. However, subtle adjustments in tissue hydration seemed to occur, particularly during stiffening.
A facilitative versus directive approach in training clinical skills? Investigating
students’ clinical performance and perceptions
Authors: Berghmans Inneke , Dochy Filip , Druine Nathalie , Struyven Katrien
Published: June 2012

Over the years, many medical school curricula have started implementing diverse
student-centred teaching and learning methodologies. Previous studies, however, have
indicated that students prefer more traditional and directive methodologies instead,
raising questions on which training approach should be advocated. This study contrasts
the effects of a student-centred (i.e. facilitative) training approach on students’
clinical skills learning with students’ perceptions. More specifically, a
quasi-experimental study was set up in which students experienced either a directive or
facilitative training approach. Data were collected by means of an OSCE on the one hand,
and a questionnaire on students’ perceptions of the training sessions, and two
open-ended questions about students’ likes and dislikes on the other hand. While no
general differences were found in terms of clinical knowledge and understanding, and
actual clinical performance, an interaction between students’ course-specific prior
knowledge and the training approach was found. Especially students with low levels of
knowledge benefited more from the facilitative training approach in terms of clinical
knowledge, while highly knowledgeable students experienced a negative effect of this
training approach. Moreover, students’ perceptions revealed that facilitative-trained
students reported more deep-level learning, while the directive training approach turned
out to score higher in terms of quality and perceived effects.
Activity Participation Differences Between Younger and Older Individuals with Stroke
Authors: Wolf Timothy J. , Brey Joseph K. , Baum Carolyn , Connor Lisa Tabor
Published: June 2012

The purpose of this study was to describe differences in activity participation between younger and older individuals with stroke to inform transition after stroke. This was a cross-sectional study with individuals six-months poststroke (n = 177). All individuals completed an outcomes assessment battery that included the Stroke Impact Scale, the Reintegration to Normal Living Index and the Activity Card Sort. The sample was divided into two groups: (1) Young — those under the age of 65 (n = 89); and (2) Old — those 65 or older (n = 88). Analysis was completed to examine differences between the groups on the primary outcome measures of the study and to look at differences between the groups on individual questions/items on the specific measures. The results of this study demonstrate: (1) significant differences in both the quantity and nature of activity participation prior to and after stroke between younger and older stroke survivors and (2) total scores and measures of central tendency do not necessarily provide therapists with the information they need to guide treatment. Rehabilitation professionals should focus on providing clients with the tools they will need to be successful in transitioning back to home and community environments once rehabilitation has ended.
Transition to Community Living After Acquired Brain Injury
Authors: Gustafsson Louise , Fleming Jennifer
Published: June 2012

Enter the word ‘transition’ into an internet search engine and you will be overwhelmed by the number of web pages that talk about transitions from an economical, scientific, literary or organisational perspective (just to name a few). Common to the description of transition from the differing perspectives is the inclusion of the terms movement and/or change from one state to the next. It is important that healthcare professionals who work with people with both traumatic and nontraumatic brain injury appreciate and understand that from the point of brain insult, the patient and their family will experience multiple transitions involving movement or change in ‘state’, such as changes to roles and altering levels of participation and activity.
Clinicians’ Expectations and Early Experiences of a New Comprehensive Rehabilitation Case Management Model in a Specialist Brain Injury Rehabilitation Unit
Authors: Kennedy Nicole , Barnes Jessica , Rose Anna , Veitch Craig
Published: June 2012

This article presents early findings from the implementation and ongoing evaluation of a new model of care that employs a comprehensive approach to rehabilitation case management for clients with traumatic brain injury, with the aim of improving transition from inpatient rehabilitation to community settings. The evaluation explores the design, implementation, utility and acceptability of the new model using clinicians’ perceptions and experiences. Method: The evaluation framework employs a participatory evaluation approach, drawing on semistructured interview data. Interviews were conducted with brain injury unit clinicians, rehabilitation case managers and external stakeholders at the model's implementation and four months later, as part of a 12-month evaluation period. The data were descriptively organised, then coded and subjected to interpretative analysis to identify key issues. Results: Early findings suggest that the new model provides increased consistency for staff, clients and carers; promotes efficiency in discharge planning and facilitates a more streamlined and seamless transition between inpatient rehabilitation and community services. Data gathered across the remainder of the implementation trial will extend understanding of this comprehensive rehabilitation case management model and its potential utility in other services and settings.
Accommodation Outcomes and Transitions Following Community-Based Intervention for Individuals with Acquired Brain Injury
Authors: Sloan Sue , Callaway Libby , Winkler Dianne , McKinley Kirsten , Ziino Carlo
Published: June 2012

Objectives: To explore living situation, support and participation outcomes of people with severe acquired brain injury (ABI) residing in either home-like or disability-specific accommodation settings, who were provided with 3 years of occupational therapy intervention based on the Community Approach to Participation (CAP).

To examine transitions for a subgroup whose accommodation and support model changed during this 3-year period and identify factors critical to this change.

Method: Forty-three participants who had sustained severe to extremely severe ABI, and were an average of 6.73 years post-injury, were provided with CAP intervention over a 3-year period. Living situation and support model, participation levels and accommodation transition data were collected at four time points.

Results: Participants were living in a range of home-like and disability-specific accommodation settings at baseline. The disability-specific accommodation group had mainly noncompensable injuries and required a significantly higher level of daily support at all four time points. They also received higher total hours of support, which averaged 170.83 hours per week at baseline and did not change significantly over the 3 years. In contrast, 86% of the participants residing in home-like settings had compensable injuries and received an average of 91.46 hours of support per week at baseline. This reduced to 70.97 hours per week over the 3-year intervention period, a change that was statistically significant.

Conclusion: It is possible to achieve accommodation transitions to more independent, home-like situations many years post-injury and regardless of injury severity. Home-like settings provide scope to adjust support along a continuum to reflect gains in independence, community integration and role participation that the fixed models and hours of support in disability-specific accommodation do not. Over time, these gains can flow into a significant reduction in hours of support.
Analysis of One Stroke Survivor's Transition into Vocational Experiences
Authors: Gustafsson Louise , Turpin Merrill
Published: June 2012

Background and Aims: Return to work presents a unique transition for the person with mild stroke who is often unsupported and does not anticipate difficulties from hidden impairments. The aim of this study was to explore the return to work experience from the perspective of one person with mild stroke.

Methods: An inductive thematic analysis was undertaken with a narrative of e-mail correspondence from a person with mild stroke. The analysis follows the participant from three to six years after stroke during a process of upskilling and training for return to work.

Results: The female participant was 32 years old at the time of stroke and returned to tertiary studies after experiencing difficulties with initial return to work. Four themes emerged from the analysis of the narrative: I don't know which identity to choose, My anxieties and reactions, I need support and structure, and I am exhausted.

Discussion: The results demonstrate the impact of hidden impairments on the struggle to reconcile a past with present identity. The process of reconciliation was ongoing and dependent on work-based experiences that enhanced understanding of strengths and limitations, and required adaptations. The impact of fatigue on performance in work and non-work time was highlighted.
Mathematical Methods in Electrical Engineering
Authors: Senior Thomas B. A.
Published: June 2012

In this volume, the author covers the mathematical methods appropriate to both linear-systems theory and signal processing. The text deals with a number of topics usually found in introductory linear-systems courses, such as complex numbers and Laplace transforms, and addresses additional topics such as complex variable theory and Fourier series and transforms. Although the discussion is mathematically self-contained, it assumes that the reader has a firm background in calculus and differential equations. Each chapter contains a number of worked examples plus exercises designed to allow the student to put concepts into practice. The author writes in a mathematically elegant yet relaxed and readable style, and provides interesting historical notes along the way. Undergraduate students of electrical engineering, applied mathematics, and related disciplines - and their teachers - will welcome this book.
Plays by Susan Glaspell
Authors: Glaspell Susan
Published: June 2012

A cofounder of the Provincetown Players - the group that acted as midwife to the American theatre - Susan Glaspell (1876–1948) can also lay claim to be a major figure in her own right. Her early plays were in many respects as challenging and original as those with which O'Neill made his debut. Her concern with language as subject, with character as an expression of social role, with plot as a mechanism that may ensnare rather than locate the self, mode her very much a modern. In Trifles (1916) she developed a feminist critique of social role. In The Outside (1917) she staged a debate between the life force and a perverse celebration of death. In both plays silence becomes an eloquent expression of meaning. The Verge (1921) is an experimental work of considerable proportions, more daring in many ways than anything attempted by O'Neill. Though Inheritors (1921) is far more conventional it touched a contemporary nerve, questioning the nature and reality of American pieties. Long known only for a single play, Susan Glaspell now emerges as a significant figure in the history of American drama, a woman of genuine creative daring.
Leafwise homotopy equivalences and leafwise Sobolov spaces
Authors: Benameur Moulay-Tahar , Heitsch James L.
Published: June 2012

We prove that a leafwise homotopy equivalence between compact foliated manifolds induces a well defined bounded operator between all Sobolov spaces of leafwise (for the natural foliations of the graphs of the original foliations) differential forms with coefficients in a leafwise flat bundle. We further prove that the associated map on the leafwise reduced L2 cohomology is an isomorphism which only depends on the leafwise homotopy class of the homotopy equivalence.
Report on locally finite triangulated categories
Authors: Krause Henning
Published: June 2012

The basic properties of locally finite triangulated categories are discussed. The focus is on Auslander–Reiten theory and the lattice of thick subcategories.
Hodge realizations of 1-motives and the derived Albanese
Authors: Vologodsky Vadim
Published: June 2012

We prove that the embedding of the derived category of 1-motives up to isogeny into the triangulated category of effective Voevodsky motives, as well as its left adjoint functor LAlbℚ, commute with the Hodge realization. This result yields a new proof of the rational form of Deligne's conjecture on 1-motives.
K1 of Exact Categories by Mirror Image Sequences
Authors: Sherman Clayton
Published: June 2012

We establish a presentation for K1 of any small exact category P, based on the notion of “mirror image sequence,” originally introduced by Grayson in 1979; as part of the proof, we show that every element of K1(P) arises from a mirror image sequence. This provides an alternative to Nenashev's presentation in terms of “double short exact sequences.”
Two-dimensional magnetohydrodynamic turbulence in the small magnetic Prandtl number limit
Authors: Dritschel David G. , Tobias Steven M.
Published: June 2012

In this paper we introduce a new method for computations of two-dimensional magnetohydrodynamic (MHD) turbulence at low magnetic Prandtl number $\mathit{Pm}= \nu / \eta $. When $\mathit{Pm}\ll 1$, the magnetic field dissipates at a scale much larger than the velocity field. The method we utilize is a novel hybrid contour–spectral method, the ‘combined Lagrangian advection method’, formally to integrate the equations with zero viscous dissipation. The method is compared with a standard pseudo-spectral method for decreasing $\mathit{Pm}$ for the problem of decaying two-dimensional MHD turbulence. The method is shown to agree well for a wide range of imposed magnetic field strengths. Examples of problems for which such a method may prove invaluable are also given.
Intergenerational transmission of maltreatment and psychopathology: the
role of antenatal depression
Authors: Plant D. T. , Barker E. D. , Waters C. S. , Pawlby S. , Pariante C. M.
Published: June 2012

Background

Maternal experience of childhood maltreatment and maternal antenatal depression
are both associated with offspring childhood maltreatment and offspring adjustment
problems. We have investigated the relative impact of maternal childhood
maltreatment and exposure to depression in utero on offspring
maltreatment and psychopathology.

Method

The sample included 125 families from the South London Child Development Study. A
prospective longitudinal design was used. Data on maternal childhood maltreatment,
maternal antenatal depression (36 weeks of pregnancy), offspring childhood
maltreatment (age 11 years) and offspring adolescent antisocial behaviour and
depression (ages 11 and 16 years) were obtained from parents and offspring through
clinical interview.

Results

Mothers who experienced childhood maltreatment were significantly more likely to
be depressed during pregnancy [odds ratio (OR) 10.00]. Offspring of mothers who
experienced only childhood maltreatment or only antenatal depression were no more
at risk of being maltreated or having psychopathology; however, offspring of
mothers who experienced both maternal childhood maltreatment and antenatal
depression were exposed to significantly greater levels of childhood maltreatment
and exhibited significantly higher levels of adolescent antisocial behaviour
compared with offspring not so exposed. Furthermore, maternal childhood
maltreatment accounted for a significant proportion of the variance in offspring
childhood maltreatment in only those offspring exposed to depression in
utero.

Conclusions

Maternal childhood maltreatment and maternal antenatal depression are highly
associated. The co-occurrence of both insults significantly increases the risk of
offspring adversity. The antenatal period is an optimum period to identify
vulnerable women and to provide interventions.
Diagnosis of the soft X-ray spectrum emitted by laser-plasmas using a spectroscopic photon sieve
Authors: Gao Yulin , Zhou Weimin , Wei Lai , Cao Leifeng , Zhu Xiaoli , Zhao Zongqing , Gu Yuqiu , Zhang Baohan , Xie Changqing
Published: June 2012

Laser plasma experiments, which demonstrated the single order diffraction property of spectroscopic photon sieve (a novel single-order diffraction grating), were performed on the SILEX-I femto-second laser facility. High-intensity laser radiation was focused onto a Cu target to generate plasma. The spectra of soft X-ray from copper plasmas have been measured with spectroscopic photon sieve based spectrograph. The results show that the spectroscopic photon sieve is able to provide soft X-ray spectrum free from higher-order diffraction components. The measured spectra obtained with such a spectroscopic photon sieve need no unfolding process to extract higher-order diffraction interference.
The systemic right ventricle in congenitally corrected transposition of the great arteries is different from the right ventricle in dextro-transposition after atrial switch: a cardiac magnetic resonance study
Authors: Grothoff Matthias , Fleischer Antje , Abdul-Khaliq Hashim , Hoffmann Janine , Lehmkuhl Lukas , Luecke Christian , Gutberlet Matthias
Published: June 2012

Background

Patients with a congenitally corrected transposition of the great arteries show an increasing incidence of cardiac failure with age. In other systemic right ventricles, such as in dextro-transposition after atrial switch, excessive hypertrophy is a potential risk factor for impaired systolic function. In this trial, we sought to compare systemic function and volumes between patients with congenitally corrected transposition and those with dextro-transposition after atrial switch by using cardiac magnetic resonance imaging.

Methods and Results

A total of 19 patients (nine male) with congenitally corrected transposition and 31 patients (21 male) with dextro-transposition after atrial switch were studied using a 1.5-Tesla scanner. Cine steady-state free-precession sequences in standard orientations were acquired for volumetric and functional imaging. Patient parameters were compared with those of a group of 25 healthy volunteers. Although patients with congenitally corrected transposition were older, they presented with higher right ventricular ejection fractions (p = 0.04) compared with patients with dextro-transposition. Patients with congenitally corrected transposition showed a weak negative correlation between age at examination and systemic ejection fraction (r = −0.18, p = 0.04) but no correlation between right ventricular myocardial mass index and ejection fraction. There was no significant difference in the right ventricular end-diastolic volumes between both patient groups.

Conclusion

Although patients with congenitally corrected transposition had a longer pressure load of the systemic right ventricle, ventricular function was better compared with that in patients with dextro-transposition after atrial switch. The results suggest that the systemic ventricles might have partly different physiologies. One difference could be the post-operative situation after atrial switch, which results in impaired atrial contribution to ventricular filling.
Placental fatty acid transport in maternal obesity
Authors: Cetin I. , Parisi F. , Berti C. , Mandò C. , Desoye G.
Published: June 2012

Pregestational obesity is a significant risk factor for adverse pregnancy outcomes. Maternal obesity is associated with a specific proinflammatory, endocrine and metabolic phenotype that may lead to higher supply of nutrients to the feto-placental unit and to excessive fetal fat accumulation. In particular, obesity may influence placental fatty acid (FA) transport in several ways, leading to increased diffusion driving force across the placenta, and to altered placental development, size and exchange surface area. Animal models show that maternal obesity is associated with increased expression of specific FA carriers and inflammatory signaling molecules in placental cotyledonary tissue, resulting in enhanced lipid transfer across the placenta, dislipidemia, fat accumulation and possibly altered development in fetuses. Cell culture experiments confirmed that inflammatory molecules, adipokines and FA, all significantly altered in obesity, are important regulators of placental lipid exchange. Expression studies in placentas of obese–diabetic women found a significant increase in FA binding protein-4 expression and in cellular triglyceride content, resulting in increased triglyceride cord blood concentrations. The expression and activity of carriers involved in placental lipid transport are influenced by the endocrine, inflammatory and metabolic milieu of obesity, and further studies are needed to elucidate the strong association between maternal obesity and fetal overgrowth.
Stabilität von Persönlichkeitspathologie bei jugendlichen Delinquenten
Authors: Krischer Maya K. , Pukrop Ralf , Halstenberg Alina , Lehmkuhl Gerd , Sevecke Kathrin
Published: June 2012

In dieser Follow-up-Studie wurde die Stabilität dimensional erfasster Persönlichkeitspathologie in einer Stichprobe ehemals inhaftierter weiblicher und männlicher Jugendlicher nach Ablauf von anderthalb Jahren untersucht. Es wurden 71 weibliche und männliche Jugendliche aus einer Kohorte vormals Inhaftierter im Mittel 17,1 Monate nach der Ersterhebung mit dem Dimensional Assessment of Personality Pathology- Basic Questionnaire (DAPP-BQ) nachuntersucht. Zur Klärung der Frage einer signifikanten Mittelwertsveränderung über die beiden Erhebungszeitpunkte hinweg wurde eine univariate Varianzanalyse mit Messwiederholung und zudem Rangkorrelationen berechnet. Die Ausprägungen für die DAPP-Subskalen Kognitive Verzerrung, Affektive Labilität, Argwohn, Unsichere Bindung, Reizsuche und Hartherzigkeit erwiesen sich als stabil. Demgegenüber waren signifikante Mittelwertsveränderungen bezüglich Identitätsprobleme, Oppositionalität, Selbstschädigung und Verhaltensprobleme auszumachen. Die vorliegenden Resultate entsprachen Ergebnissen mehrerer aktueller longitudinaler Studien. Als instabil erwiesen sich von anderen Autoren als „dysfunktionales Verhalten“ beschriebene persönlichkeitspathologische Merkmale, wohingegen stabilere Resultate für Persönlichkeitstraits (z. B. affektive Labilität und Hartherzigkeit) vorlagen. Diese Ergebnisse verweisen darauf, dass sich auch in einer Hochrisikopopulation delinquenter Jugendlicher das Konstrukt Persönlichkeit aus stabilen und instabilen Anteilen zusammensetzt. Die Auswirkungen auf die klinische Praxis werden diskutiert.
Das Psychopathy-Konzept bei Mädchen
Authors: Sevecke Kathrin , Franke Sebastian , Lehmkuhl Gerd , Krischer Maya K.
Published: June 2012

Die vorliegende Studie untersucht die Validität des Psychopathy-Konzepts bei delinquenten Mädchen und widmet sich der Frage, inwiefern sich Unterschiede zwischen Mädchen mit und ohne Psychopathy-Eigenschaften finden lassen. Anhand der Ergebnisse aus der Psychopathy-Checkliste Youth Version (PCL:YV) wurden 171 inhaftierte Mädchen (14 – 19 Jahre) in eine Gruppe mit hochausgeprägten Callous-unemotional Traits (CU-Gruppe), in eine mit hochausgeprägtem aggressiv-impulsivem Verhalten (Behavioral-Gruppe) sowie in eine Gruppe ohne Psychopathy-Eigenschaften eingeteilt und hinsichtlich allgemeiner Psychopathologie, ADHS, Traumatisierung, Heimaufenthalten sowie Gewaltdelikten mit Hilfe einfaktorieller ANOVAs verglichen. 30 % der Mädchen wiesen Psychopathy-Eigenschaften im Sinne von hochausgeprägten CU-Traits auf, 40 % zeigten ausschließlich extrem impulsiv-aggressives Verhalten. 15 % ließen sich aufgrund ihrer zu geringen Psychopathy-Ausprägung keiner Gruppe zuordnen, bei 15 % lagen keinerlei Auffälligkeiten vor. Sowohl die CU- als auch die Behavioral-Gruppe wiesen im Vergleich zu den Mädchen ohne Psychopathy signifikant mehr ADHS-Symptome sowie externalisierendes und internalisierendes Verhalten auf. Außerdem gaben sie mehr emotionale Misshandlung und mehr Heimaufenthalte an. Die beiden Psychopathy-Gruppen unterschieden sich nur dahingehend, dass die Behavioral-Gruppe signifikant mehr Gewaltstraftaten und Verurteilungen zeigten. Die gefundenen Unterschiede zwischen den delinquenten Mädchen mit hoch ausgeprägten Psychopathy-Eigenschaften im Vergleich zu denen ohne Psychopathy stärken die Annahme, dass es sich um ein valides Konzept handelt, welches eine spezifische Subgruppe unterscheiden kann. Gleichzeitig wird aufgrund der Heterogenität des Konzepts–Persönlichkeitsdimensionen sowie Verhaltensdimensionen–deutlich, dass eine differenzierte Betrachtung der Psychopathy-Dimensionen von übergeordneter Bedeutung ist.
Global response of the ionosphere to atmospheric tides forced from below: Comparison between COSMIC measurements and simulations by atmosphere‐ionosphere coupled model GAIA
Authors: Pancheva D. , Miyoshi Y. , Mukhtarov P. , Jin H. , Shinagawa H. , Fujiwara H.
Published: June 2012

This paper for the first time presents a detailed comparison between simulated and observed global electron density responses to different atmospheric tides forced from below. The recently developed Earth's whole atmospheric model from the troposphere to the ionosphere, called GAIA, has been used for the simulation of the electron density tidal responses. They have been compared with the extracted from the COSMIC electron density data tidal responses for the period of time October 2007 to March 2009. Particular attention has been paid to the nonmigrating DE3/DE2 and migrating DW1, SW2 and TW3 electron density responses. The GAIA model reproduced quite well the COSMIC DE3/DE2 responses. Both simulations and observations revealed three altitude regions of enhanced electron density responses: (1) an upper level response, above 300 km height, apparently shaped mainly by the “fountain effect”; (2) a response located near altitudes of ∼200–270 km, and (3) a lower thermospheric response situated near 120–150 km height. A possible mechanism is suggested for explaining the two lower level responses. For the first time the GAIA model simulations supported the observational evidence found in the COSMIC measurements that the ionospheric WN4 (WN3) longitude structure is not generated only by the DE3 (DE2) tide as it has been often assumed. As regards the comparison of the migrating DW1, SW2 and TW3 responses the obtained results clearly demonstrate that the GAIA model reproduce very well of the SW2 and TW3 COSMIC electron density responses. The only main discrepancy is seen in the migrating DW1 response; the observation does not support the splitting of the simulated response at both sides of the equator. This is due mainly to the difference between the SABER and GAIA SW2 tide in the lower thermosphere as it turned out that the DW1 electron density response strongly depends on the mean features of the lower thermospheric SW2 tide.
Water mass bio‐optical properties in the Monterey Bay region: Fluorescence‐based inference of shifts in phytoplankton photophysiology
Authors: Jolliff J. K. , Gould R. W. , Penta B. , Teague W. J. , DeRada S. , Chavez F. P. , Arnone R. A.
Published: June 2012

A physical and bio‐optical field survey of the Monterey Bay area was conducted during May–June 2008. The combined bio‐optical and physical data may be summarized as a transition between two end‐member states during the late spring to summer upwelling season: (1) the mesotrophic, nanoflagellate‐dominated, low‐salinity surface waters (chlorophyll‐a ∼ 0.5–2 mg m−3; S < 33.4) of the California Current and (2) the eutrophic, diatomaceous, higher salinity surface waters (chlorophyll‐a > 2 mg m−3; S > 33.8) of Monterey Bay and adjacent continental shelf areas. High‐resolution and collocated spectrophotometric, fluorometric and CTD data obtained from a towed platform indicated low‐salinity subarctic‐origin surface waters intruded into Monterey Bay on 4 June. The dark in vivo fluorometry (IVF) phytoplankton response normalized to particle absorption at 676 nm (the apparent fluorescence efficiency, AFE) was nearly fourfold larger in this water mass type compared to higher salinity surface waters more typical of Monterey Bay. The collocated fluorescence and optical data were then used to estimate in situ irradiance values and determine apparent light saturation intensities (I′k) based on the remarkably consistent AFE water column inflection points. I′kvalues retrieved from the low‐salinity surface waters were approximately half those obtained over the continental shelf. An analysis of concomitant HPLC data, in addition to historical data for the region, suggest these observed fluorescence trends may be indicative of taxon‐specific variation in photophysiology. Specifically, the subarctic water mass‐associated pelagic nanoflagellate group likely possesses a fundamentally different photosynthetic architecture than large diatoms prototypical of coastal upwelling regimes.
The Makassar Strait throughflow and its jet
Authors: Mayer B. , Damm P. E.
Published: June 2012

A nested numerical model system has been set up to realistically simulate almost 40 years of the Indonesian throughflow (ITF). A global circulation model delivered the boundary values for sea surface height, temperature and salinity distribution to a fine resolution regional model of the ITF. The results of the regional model are in good agreement with measured data regarding velocity distribution, stratification as well as transported water masses, even though the division of the ITF volume transport into its western and eastern branches differs slightly from estimates from other model results or measurements. The results show a current system highly variable in space and time. Here, the analysis of model results focuses on the western branch of the ITF, the Makassar Strait throughflow, which is estimated to account for up to 50 to 80% of the entire ITF. The climatology and the mean vertical structure are presented. The model results show that the Makassar Strait throughflow occurs as a distinct current, which we termed Makassar Current. It is regionally developed as a subsurface jet, and it behaves like a western boundary current as it is attached to the western boundary (Sunda Shelf edge) along its entire path from the Sulawesi Sea through the Makassar Strait to its direct exit through the Lombok Strait. It appears from model experiments that the local wind stress counteracts the Makassar Strait throughflow.
Subsurface damage from oblique impacts into low‐impedance layers
Authors: Stickle A. M. , Schultz P. H.
Published: June 2012

Layered planetary surfaces occur ubiquitously in the solar system, where sedimentary sequences or icy layers overlay crystalline bedrock. Previous experimental studies investigated how the presence of weak layer overlying a strong basement affects crater morphology, subsurface damage and soft‐sediment compression. Numerical studies generally focus on the final morphology as a function of thicknesses and burial depths of weak layers. In field studies of impact craters, the shock state of minerals is a key metric. Here, we evaluate the effect of a surficial low‐impedance layer on peak pressure magnitudes and consequent damage extent in the competent substrate. Laboratory experiments coupled with 3D CTH models of oblique (30° from horizontal) hypervelocity impacts at laboratory and planetary scales show that surface layers with a thickness on the order of the projectile diameter shield the underlying surface and absorb/scatter ∼70% of the impact energy. Numerical simulations reveal that surficial layers reduce peak pressure magnitudes within the subsurface by ∼60–70%, while damage in the substrate is due to shear failure. Sedimentary layers are more efficient shields than icy layers, but both reduce the extent of subsurface damage and the resulting shock levels recorded by minerals. These results indicate that a thin surficial low impedance layer mitigates the expression of shocked minerals in the substrate even when a structural response is still observed.
Darcy‐scale modeling of microbially induced carbonate mineral precipitation in sand columns
Authors: Ebigbo A. , Phillips A. , Gerlach R. , Helmig R. , Cunningham A. B. , Class H. , Spangler L. H.
Published: June 2012

This investigation focuses on the use of microbially induced calcium carbonate precipitation (MICP) to set up subsurface hydraulic barriers to potentially increase storage security near wellbores of CO2 storage sites. A numerical model is developed, capable of accounting for carbonate precipitation due to ureolytic bacterial activity as well as the flow of two fluid phases in the subsurface. The model is compared to experiments involving saturated flow through sand‐packed columns to understand and optimize the processes involved as well as to validate the numerical model. It is then used to predict the effect of dense‐phase CO2 and CO2‐saturated water on carbonate precipitates in a porous medium.
Holocene sea‐level change and Antarctic melting history derived from geological observations and geophysical modeling along the Shimokita Peninsula, northern Japan
Authors: Yokoyama Yusuke , Okuno Jun'ichi , Miyairi Yosuke , Obrochta Stephen , Demboya Nobuhiro , Makino Yoshinori , Kawahata Hodaka
Published: June 2012

A Mid to Late Holocene sea‐level record based on combined geomorphological, geological and micropaleontological observations was obtained from well‐developed wave cut benches subaerially exposed along the Shimokita Peninsula, northern Japan. Results indicate that the benches were formed during mid to late Holocene sea‐level transgressions, reaching a maximum highstand level of 2 m above present at about 4,000 years ago. This timing corresponds to an abrupt, order of magnitude decrease in sedimentation rate as recorded in a core recovered from proximal Mutsu Bay. In addition, glacio‐hydro‐isostatic adjustment due to crustal deformation in response to postglacial sea‐level rise was modeled, and results are consistent with the reconstructed local 2 m highstand. Given that meltwater contributions from the major North American and European ice sheets had largely ceased by 7,000 years ago, these independent lines of evidence, taken together, indicate that melting of the Antarctic ice sheet ended by 4,000 years ago.
Sardine biomass is poorly correlated with the Pacific Decadal Oscillation off California
Authors: McClatchie Sam
Published: June 2012

Pacific sardines (Sardinops sagax) fluctuate widely in abundance over interannual to multidecadal time scales. For Pacific sardines, there have been repeated attempts to link fluctuations in biomass to indices of climatic variability, such as the Pacific Decadal Oscillation (PDO). Correlations between the PDO with periods of 40–76 years, and sardine biomass with periods of 40–70 years, have been inferred using 90‐year time series (e.g. 1920–2010). The inferred correlations cannot be tested because the long‐period fluctuations are outside the observation window that can be analysed statistically, i.e. the period (40–76 years) is greater than half the length of the series (45 years). To date, there has been no attempt to test the relationship between low‐frequency fluctuations of sardine biomass and the PDO using longer paleoclimatic time series proxies for sardine biomass and the PDO. Here we use a 370‐year record of paleoclimatic proxies to show that fluctuations in sardine biomass off California are not related to the PDO, despite the appearance of correlation in the 90‐year record from 1920 to the present day.
Seismic tomography of Shatsky Rise by adaptive importance sampling
Authors: Korenaga J. , Sager W. W.
Published: June 2012

We present results from a wide‐angle seismic refraction survey over Shatsky Rise, a large oceanic plateau in the northwestern Pacific. A new Monte Carlo sampling scheme is developed to explore comprehensively the model space of crustal velocity structure by joint refraction and reflection seismic tomography. The new scheme, which is founded on the notion of adaptive importance sampling, is made possible by the combination of several independent developments, including the introduction of effective model parameters, the implementation of automated model regularization, and a polynomial expansion of the probability density function. From 21 ocean‐bottom instruments deployed along a 420‐km‐long refraction transect, we collect 16446 Pg and 4735 PmP travel times, which are inverted to construct a two‐dimensional compressional velocity model across the major axis of Shatsky Rise. The convergence of Monte Carlo sampling is tested by running parallel sampling chains, and the effective dimensions of the model space are estimated to be ∼10 by principal component analysis. The thickness of the rise crust varies from ∼9 km to ∼30 km, and the average velocity of the lower crust ranges from ∼7.0 km s−1 to ∼7.2 km s−1. One standard deviation uncertainty for whole‐crustal thickness and average lower‐crustal velocity is <1 km and ∼0.05 km s−1, respectively, for most of the model domain. Shatsky Rise crustal structure exhibits a negative correlation between crustal thickness and velocity, which implies that a chemically anomalous mantle may have been responsible for the formation of the rise.
Abnormal upwelling and chlorophyll‐a concentration off South Vietnam in summer 2007
Authors: Liu Xin , Wang Jing , Cheng Xuhua , Du Yan
Published: June 2012

The present study investigates a strong upwelling and concurrent phytoplankton bloom off the South Vietnam coast in August 2007. Analysis of the alongshore wind, offshore Ekman transport, wind stress curl and other parameters indicates the southwesterly summer monsoon plays an important role in this peculiar case. The change of monsoonal wind involves variations of atmospheric circulation on multiple time scales. On the interannual time scale, a positive Indian Ocean Dipole (IOD) in 2007 accompanying with a La Niña event acts to enhance the southwesterly monsoon over the South China Sea (SCS). The enhanced southwesterly wind is regarded as a major factor in promoting the upwelling and the phytoplankton bloom off the South Vietnam coast. On the intraseasonal time scale, variations of the sea surface temperature (SST) and sea surface wind at 30–60 day periods reveal that the SST cooling develops with the evolution of the southwesterly wind anomalies with nearly one week delay, implying the great significance of the Madden‐Julian Oscillation (MJO). Moreover, a tropical storm formed in the western SCS in early August reinforces the westerly wind and SST cooling. Among multiple factors on different time scales, the MJO event is considered as the major cause, since it induces the maximum velocity (4 m/s) of the southwesterly wind anomalies. As a result, the high chlorophyll‐a concentration (>0.56 mg/m3) and low SST center (<27°C) develops in the region off the South Vietnam coast and advects to the central SCS, riding on the northern rim of the southern anticyclonic gyre.
Nearshore internal bores and turbulent mixing in southern Monterey Bay
Authors: Walter Ryan K. , Woodson C. Brock , Arthur Robert S. , Fringer Oliver B. , Monismith Stephen G.
Published: June 2012

We observed transient stratification and mixing events associated with nearshore internal bores in southern Monterey Bay using an array of instruments with high spatial and temporal resolution. The arrival of the bores is characterized by surging masses of dense (cold) water that tend to stratify the water column. The bore is followed by a gradual drop in the temperature throughout the water column over several hours (defined here as the bore period) until a sharp warm‐front relaxation, followed by high frequency temperature fluctuations, returns the column back to nearly its original state (defined here as the mixing period). Mixing periods revealed increased temperature variance at high frequencies (ω >
), as well as a greater percentage of events where dynamic instabilities may be present (Ri< 0.25), suggesting active mixing of the stratified water column. Turbulent dissipation rates in the stratified interior during the mixing period, estimated using the technique of isopycnal slope spectra, revealed mean values the same order of magnitude as near‐bed bottom‐generated turbulence. Observations indicate that local shear‐produced turbulent kinetic energy by the warm front relaxations dominates mixing in the stratified interior. The non‐canonical nature of these bore and relaxation events is also investigated with a numerical model, and the dynamics are shown to depend on the internal Iribarren number. Our results suggest that nearshore internal bores interacting with local bathymetry dramatically alter local dynamics and mixing in the nearshore with important ecological implications.
Wp index: A new substorm index derived from high‐resolution geomagnetic field data at low latitude
Authors: Nosé M. , Iyemori T. , Wang L. , Hitchman A. , Matzka J. , Feller M. , Egdorf S. , Gilder S. , Kumasaka N. , Koga K. , Matsumoto H. , Koshiishi H. , Cifuentes‐Nava G. , Curto J. J. , Segarra A. , Çelik C.
Published: June 2012

Geomagnetic field data with high time resolution (typically 1 s) have recently become more commonly acquired by ground stations. Such high time resolution data enable identifying Pi2 pulsations which have periods of 40–150 s and irregular (damped) waveforms. It is well‐known that pulsations of this type are clearly observed at mid‐ and low‐latitude ground stations on the nightside at substorm onset. Therefore, with 1‐s data from multiple stations distributed in longitude around the Earth's circumference, substorm onset can be regularly monitored. In the present study we propose a new substorm index, the Wp index (Wave and planetary), which reflects Pi2 wave power at low‐latitude, using geomagnetic field data from 11 ground stations. We compare the Wp index with the AE and ASY indices as well as the electron flux and magnetic field data at geosynchronous altitudes for 11 March 2010. We find that significant enhancements of the Wp index mostly coincide with those of the other data. Thus the Wp index can be considered a good indicator of substorm onset. The Wp index, other geomagnetic indices, and geosynchronous satellite data are plotted in a stack for quick and easy search of substorm onset. The stack plots and digital data of the Wp index are available at the Web site (http://s‐cubed.info) for public use. These products would be useful to investigate and understand space weather events, because substorms cause injection of intense fluxes of energetic electrons into the inner magnetosphere and potentially have deleterious impacts on satellites by inducing surface charging.
An extension of the capillary and thin film flow model for predicting the hydraulic conductivity of air‐free frozen porous media
Authors: Lebeau Marc , Konrad Jean‐Marie
Published: June 2012

Hydraulic conductivity of frozen air‐free porous media is a rather elusive property that remains largely undefined in much of the literature. According to modern science, water transport in frozen porous media occurs mostly in ice‐free capillaries at temperatures close to the freezing point of pure water and through a thin liquid interlayer, between solid particle and ice, at lower temperatures. In accordance with this understanding, this paper extends the capabilities of an existing capillary and thin film flow model to include the prediction of hydraulic conductivity in frozen air‐free porous media. As such, hydraulic conductivity of the frozen porous media is predicted with a simple capillary bundle model as well as with a new hydrodynamic model of thin interlayer flow in which film thickness is controlled by both London‐van der Waals and ionic‐electrostatic forces. As with other predictive models of hydraulic conductivity, most model parameters are derived from more easily measured water content data in either ice‐free (water retention function) or air‐free (water freezing function) porous media. Model results showed very good agreement with observed values of hydraulic conductivity taken at thermal equilibrium, and illustrated the importance of thin interlayer flow at lower temperatures.