bluuebunny/crossref_metadata_2025 huggingface dataset:
Long‐lastingD‐region ionospheric modifications, caused by intense lightning in association with elve and sprite pairs
Authors: Haldoupis Christos , Cohen Morris , Cotts Benjamin , Arnone Enrico , Inan Umran
Published: July 2012

Observations show that intense +CG lightning discharges which trigger both an elve and a sprite are associated with long‐lasting conductivity modifications in the upperD‐region ionosphere. They are observed as strong perturbations in VLF signals propagating through the disturbed region, manifested asLOng Recovery Early VLF events (LORE), which can last up to 30 minutes. These same ionospheric modifications are also responsible for step‐like changes, seen mostly in off‐storm VLF transmissions, which offset signal levels even for longer times. The evidence suggests that when a very intense positive cloud to ground lightning stroke leads to an elve and a high altitude sprite, and possibly a sprite halo as well, there is production of long lasting elevations in electron density at VLF reflection heights that cause LOREs and severe effects on VLF propagation. The present results confirm past predictions and postulations that elves may be accompanied by long‐lasting electron density perturbations in the lower ionosphere.
Physical parameterization of Strombolian eruptions via experimentally‐validated modeling of high‐speed observations
Authors: Taddeucci J. , Alatorre‐Ibargüengoitia M. A. , Moroni M. , Tornetta L. , Capponi A. , Scarlato P. , Dingwell D. B. , De Rita D.
Published: July 2012

Pressurized gas drives explosive volcanic eruptions. Existing models can predict the amount and pressure of gas in erupting magma, but application and testing of such models is currently limited by the accuracy of input parameters from natural systems. Here, we present a new methodology, based on a novel integration of 1) high‐speed imaging and 2) shock‐tube modeling of volcanic activity in order to derive estimates of sub‐second variations in the pressure, mass, and volume of gas that drive the dynamics of unsteady eruptions. First, we validate the method against laboratory‐scale shock‐tube experiments. Having validated the method we then apply it to observations of eruptions at Stromboli volcano (Italy). Finally, we use those results for a parametric study of the weight of input parameters on final outputs. We conclude that Strombolian explosions, with durations of seconds, result from discrete releases of gas with mass and pressure in the 4–714 kg and 0.10–0.56 MPa range, respectively, and which occupy the volcano conduit to a depth of 4–190 m. These variations are present both among and within individual explosions.
Statistical study of broadband whistler‐mode waves detected by Kaguya near the Moon
Authors: Tsugawa Y. , Katoh Y. , Terada N. , Ono T. , Tsunakawa H. , Takahashi F. , Shibuya H. , Shimizu H. , Matsushima M. , Saito Y. , Yokota S. , Nishino M. N.
Published: July 2012

Broadband whistler‐mode waves in the frequency range from 0.1 to 10 Hz are detected near the Moon by the Lunar Magnetometer (LMAG) on board Kaguya. The generation process and statistical properties of the waves have not been understood yet. We analyze the distributions of their occurrence and reveal that most of the waves are generated by the solar wind interaction with lunar crustal magnetic field. We also clarify that the waves are observed when Kaguya is connected by the ambient magnetic field with the lunar surface. The statistical study indicates that the broadband waves are observed in the vicinity of the region where narrowband whistler‐mode waves in the frequency of near 1 Hz are observed, showing the close relationship between them. The analysis of the wave vector directions suggests that these two types of waves are different views of the same waves propagating in the solar wind frame. The narrowband waves are possibly explained by a part of the broadband waves largely Doppler shifted in the spacecraft frame. The present results suggest a possible scenario of the generation process of the two types of waves through the solar wind interaction with the crustal magnetic field.
Interpretation of vector electric field measurements of bursty Langmuir waves in the cusp
Authors: Dombrowski M. P. , LaBelle J. , Rowland D. E. , Pfaff R. F. , Kletzing C. A.
Published: July 2012

An analysis of auroral Langmuir waves in the cusp observed by two high‐frequency electric field instruments on the TRICE high‐flyer sounding rocket shows many examples of Langmuir wave bursts modulated at approximately 10 kHz. Previous studies have explained these and similar observations as the result of beating between waves with very close frequencies near the Langmuir cutoff, resulting from either wave‐wave interactions or independent linear excitations. The unique three‐dimensional (3‐D) data set provided by the NASA Goddard Space Flight Center TAEFWD instrument shows that up to 25% of waveforms selected from the most intense bursts exhibit anisotropic modulations, i.e., the beat nulls and peaks are not aligned in time across the three perpendicular electric field components. Modulations of this type arise when superposed wave normal modes possess differing polarizations, and simulations using wave modes calculated with the J‐WHAMP numerical dispersion code show (1) that waves with differing polarizations can exist in conditions like those observed by TRICE‐High and (2) that superpositions of such waves can produce anisotropic modulation. Fourier analysis of the 3‐D waveform data suggests that both linear and elliptically polarized waves are present near the Langmuir cutoff at these times. These observations illustrate how 3‐D measurements can give valuable insight into the nature of wave interactions in the auroral plasma environment.
MESSENGER observations of dipolarization events in Mercury's magnetotail
Authors: Sundberg Torbjörn , Slavin James A. , Boardsen Scott A. , Anderson Brian J. , Korth Haje , Ho George C. , Schriver David , Uritsky Vadim M. , Zurbuchen Thomas H. , Raines Jim M. , Baker Daniel N. , Krimigis Stamatios M. , McNutt Ralph L. , Solomon Sean C.
Published: July 2012

Several series of large dipolarization events are documented from magnetic field observations in Mercury's magnetotail made by the MESSENGER spacecraft. The dipolarizations are identified by a rapid (∼1 s) increase in the northward component of the magnetic field, followed by a slower return (∼10 s) to pre‐onset values. The changes in field strength during an event frequently reach 40 nT or higher, equivalent to an increase in the total magnetic field magnitude by a factor of ∼4 or more. The presence of spatially constrained dipolarizations at Mercury provides a key to understanding the magnetic substorm process in a new parameter regime: the dipolarization timescale, which is shorter than at Earth, is suspected to lead to efficient non‐adiabatic heating of the plasma sheet proton population, and the high recurrence rate of the structures is similar to that frequently observed for flux ropes and traveling compression regions in Mercury's magnetotail. The relatively short lifetime of the events is attributed to the lack of steady field‐aligned current systems at Mercury.
Equatorial trench at the magnetopause under saturation
Authors: Dmitriev A. , Suvorova A.
Published: July 2012

Magnetic data from GOES geosynchronous satellites were applied for statistical study of the low‐latitude dayside magnetopause under a strong interplanetary magnetic field of southward orientation when the reconnection at the magnetopause was saturated. From minimum variance analysis, we determined the magnetopause orientation and compared it with predictions of a reference model. The magnetopause shape was found to be substantially distorted by a duskward shifting such that the nose region appeared in the postnoon sector. At equatorial latitudes, the shape of magnetopause was characterized by a prominent bluntness and by a trench formed in the postnoon sector. The origin of distortions was regarded in the context of the storm‐time magnetospheric currents and the large‐scale quasi‐state reconnection at the dayside magnetopause.
Estimating fracture orientation from elastic‐wave propagation: An ultrasonic experimental approach
Authors: de Figueiredo J. J. S. , Schleicher J. , Stewart R. R. , Dyaur N.
Published: July 2012

Elastic‐wave propagation in fractured and cracked media depends on the dominant spatial orientation of the discontinuities. Consequently, compressional and shear‐wave velocities can give valuable information about the orientation of the cracks. The main goal of this work is to estimate the preferential fracture orientation based on an analysis of cross‐correlated S‐wave seismograms and Thomsen parameters. For this purpose, we analyzed ultrasonic measurements of elastic (P and S) waves in a physical‐modeling experiment with an artificially anisotropic cracked model. The solid matrix of the model consisted of epoxy‐resin; small rubber strips simulate cracks with a compliant fill. The anisotropic cracked model consists of three regions, each with a different fracture orientation. We used the rotation of the S‐wave polarizations for a cross‐correlation analysis of the orientations, and P‐ and S‐wave measurements to evaluate the weak anisotropic parametersγandε.The shear and compressional wave sources had dominant frequencies of 90 kHz and 120 kHz. These frequencies correspond to long wavelengths compared to the spacing between layers, indicating a nearly effective‐media behavior. Integrating the results from cross‐correlation with anisotropic parameter analysis, we were able to estimate the fracture orientation in our anisotropic cracked physical model. Theγparameter showed good agreement with the cross‐correlation analysis and, beyond that, provided additional information about the crack orientation that cross‐correlation alone did not fully resolve. Moreover, our results show that the shear waves are much more strongly influenced by, and can thus contain more information about, crack orientation than compressional waves.
Impact of inconsistent density scaling on physical analogue models of continental margin scale salt tectonics
Authors: Allen Janice , Beaumont Christopher
Published: July 2012

The influence of inaccuracies in density scaling on the structural evolution of physical analogue experiments of salt systems has been debated, and is here investigated considering a gravity spreading example. Plane strain finite element numerical analysis was used to systematically evaluate the impact of changes in density scaling on buoyancy force, sediment strength, and pressure gradient. A range of densities typical of natural systems (including compacting sediment) and physical analogue experiments was included. A fundamental shift in the structure of the salt‐sediment system, from diapir‐minibasin pairs to expulsion rollover, was observed when sediment and salt densities were altered from values typical of physical experiments (1600 and 990 kg/m3) to those most often found in nature (1900–2300 and 2150 kg/m3). Experiments equivalent to physical analogue models but with reduced sediment density showed diapir‐minibasin pair geometry, persisting to sediment densities of ∼1300 kg/m3. Salt burial by pre‐kinematic sediments was found to suppress diapir formation for thicknesses greater than ∼750 m (0.75 cm at the laboratory scale). The relative importance of disproportionately high buoyancy force, low sediment strength, and pressure gradient in physical experiments was investigated by isolating each of these scaling errors in turn. Buoyancy was found to be most influential in the development of diapir‐minibasin pairs versus expulsion rollover geometry. Finally, we demonstrate that dry physical analogue experiments with sediment density reduced to ∼1140 kg/m3 (achievable through mixing with hollow glass beads) would provide a reasonable approximation of submarine salt systems in nature (including water load and hydrostatic pore fluid pressure).
Wind and waves in extreme hurricanes
Authors: Holthuijsen Leo H. , Powell Mark D. , Pietrzak Julie D.
Published: July 2012

Waves breaking at the ocean surface are important to the dynamical, chemical and biological processes at the air‐sea interface. The traditional view is that the white capping and aero‐dynamical surface roughness increase with wind speed up to a limiting value. This view is fundamental to hurricane forecasting and climate research but it has never been verified at extreme winds. Here we show with observations that at high wind speeds white caps remain constant and at still higher wind speeds are joined, and increasingly dominated, by streaks of foam and spray. At surface wind speeds of ∼40 m/s the streaks merge into a white out, the roughness begins to decrease and a high‐velocity surface jet begins to develop. The roughness reduces to virtually zero by ∼80 m/s wind speed, rendering the surface aero‐dynamically extremely smooth in the most intense part of extreme (or major) hurricanes (wind speed > 50 m/s). A preliminary assessment shows that cross swell, dominant in large regions of hurricanes, allows the roughness under high wind conditions to increase considerably before it reduces to the same low values.
Probing local wind and temperature structure using infrasound from Volcan Villarrica (Chile)
Authors: Johnson J. B. , Anderson J. , Marcillo O. , Arrowsmith S.
Published: July 2012

We use the continuous and intense (∼107W) infrasound produced by Volcan Villarrica (Chile) to invert for the local dynamic wind and temperature structure of the atmosphere. Infrasound arrays deployed in March 2011 at the summit (2826 m) and on the NNW flank (∼8 km distant at 825 m) were used to track infrasound propagation times and signal power. We model an atmosphere with vertically varying temperature and horizontal winds and use propagation times (ranging from 23 to 24 s) to invert for horizontal slowness (2.75–2.94 s/km) and average effective sound speeds (328–346 m/s) for NNW propagating infrasound. The corresponding ratio of recorded acoustic power at proximal versus distal arrays was also variable (ranging between 0.15 to 1.5 for the peak 0.33–1 Hz infrasound band). Through application of geometrical ray theory in a uniform gradient atmosphere, these ‘amplification factors’ are modeled by effective sound speed lapse rates ranging from −15 to +4 m/s per km. NNW‐projected wind speeds ranging from −20 m/s to +20 m/s at 2826 m and wind gradients ranging from −11 to +10 m/s per km are inferred from the difference between effective sound speed profiles and adiabatic sound speeds derived from local temperature observations. The sense of these winds is in general agreement with regional meteorological observations recorded with radiosondes. We suggest that infrasound probing can provide useful spatially averaged estimates of atmospheric wind structure that has application for both meteorological observation and volcanological plume dispersal modeling.
Impact of uncertainties in atmospheric mixing on simulated UTLS composition and related radiative effects
Authors: Riese M. , Ploeger F. , Rap A. , Vogel B. , Konopka P. , Dameris M. , Forster P.
Published: July 2012

The upper troposphere/lower stratosphere (UTLS) region plays an important role in the climate system. Changes in the structure and chemical composition of this region result in particularly large changes in radiative forcings of the atmosphere. Quantifying the processes that control UTLS composition (e.g., stratosphere‐troposphere exchange) therefore represents a crucial task. We assess the influence of uncertainties in the atmospheric mixing strength on global UTLS distributions of greenhouse gases (water vapor, ozone, methane, and nitrous oxide) and associated radiative effects. The study is based on multiannual simulations with the Chemical Lagrangian Model of the Stratosphere (CLaMS) driven by ERA‐Interim meteorological data and on a state‐of‐the‐art radiance code. Mixing, the irreversible part of transport, is controlled by the local horizontal strain and vertical shear of the atmospheric flow. We find that simulated radiative effects of water vapor and ozone, both characterized by steep gradients in the UTLS, are particularly sensitive to uncertainties of the atmospheric mixing strength. Globally averaged radiative effects are about 0.72 and 0.17 W/m2for water vapor and ozone, respectively. For ozone, the largest impact of mixing uncertainties is observed in the extra‐tropical lower stratosphere.
Half‐century air temperature change above Antarctica: Observed trends and spatial reconstructions
Authors: Screen James A. , Simmonds Ian
Published: July 2012

This study provides a comprehensive analysis of observed 50‐year (1961–2010) seasonal air temperature trends from radiosonde ascents above Antarctica. Comparisons between multiple radiosonde data sets (homogenized in different ways) at each of eight Antarctic stations reveals substantial differences in the upper‐air temperature trend magnitudes and their statistical significance between data sets. However, when considering the average of these data sets at each station, or averaging across all stations, a robust vertical profile of half‐century temperature change emerges, characterized by mid‐tropospheric warming and stratospheric cooling. Statistically significant Multistation‐mean 500 hPa warming (0.1 to 0.2°C decade−1) is found in all seasons, whereas the lower stratospheric cooling has been manifest primarily in austral spring and summer, but with larger magnitudes (−1.0 to −2.0°C decade−1). We undertake the first spatial reconstructions of pan‐Antarctic upper‐air temperature trends. They strongly suggest that both the year‐round mid‐tropospheric warming and spring and summer lower stratospheric cooling have occurred above the entire continent, although their magnitudes and significance vary regionally. The reconstructed 500 hPa warming trends in winter and spring are largest over West Antarctica, the Ross Ice shelf, Victoria Land and Oates Land, and show close resemblance to those found in previously published surface temperature trend reconstructions, suggesting coupling between the surface and trends aloft. We speculate that the winter and spring mid‐tropospheric warming may, in part, be driven by tropical ocean warming, analogous to proposed mechanisms for the co‐located surface warming. The spring and summer lower stratospheric cooling is entirely consistent with the temperature response to ozone depletion.
The deposition ice nucleation and immersion freezing potential of amorphous secondary organic aerosol: Pathways for ice and mixed‐phase cloud formation
Authors: Wang Bingbing , Lambe Andrew T. , Massoli Paola , Onasch Timothy B. , Davidovits Paul , Worsnop Douglas R. , Knopf Daniel A.
Published: July 2012

Secondary organic aerosol (SOA) generated from the oxidation of organic gases are ubiquitous in the atmosphere, but their interaction with water vapor and their ice cloud formation potential at low temperatures remains highly uncertain. We report on onset conditions of water uptake and ice nucleation by amorphous SOA particles generated from the oxidation of naphthalene with OH radicals. Water uptake above 230 K was governed by the oxidation level of the SOA particles expressed as oxygen‐to‐carbon (O/C) ratio, followed by moisture‐induced phase transitions and immersion freezing. For temperatures from 200 to 230 K, SOA particles nucleated ice via deposition mode from supersaturated water vapor independent of O/C ratio at relative humidity with respect to ice (RHice) ∼10–15% below homogeneous ice nucleation limits. The glass transition temperature (Tg) for the amorphous SOA particles was derived as a function of two parameters: (1) relative humidity (RH) with respect to water and (2) oxidation level of the SOA. The data show that particle phase and viscosity govern the particles' response to temperature and RHand provide a straightforward interpretation for the observed different heterogeneous ice nucleation pathways and water uptake by the laboratory‐generated SOA and field‐collected particles. Since SOA particles undergo glass transitions, these observations suggest that atmospheric SOA are potentially important for ice cloud formation and climate.
Soil genesis on the island of Bermuda in the Quaternary: The importance of African dust transport and deposition
Authors: Muhs Daniel R. , Budahn James R. , Prospero Joseph M. , Skipp Gary , Herwitz Stanley R.
Published: July 2012

The origin of terra rossa, red or reddish‐brown, clay‐rich soils overlying high‐purity carbonate substrates, has intrigued geologists and pedologists for decades. Terra rossa soils can form from accumulation of insoluble residues during dissolution of the host limestones, addition of volcanic ash, or addition of externally derived, long‐range‐transported (LRT) aeolian particles. We studied soils and paleosols on high‐purity, carbonate aeolianites of Quaternary age on Bermuda, where terra rossa origins have been debated for more than a century. Potential soil parent materials on this island include sand‐sized fragments of local volcanic bedrock, the LRT, fine‐grained (<20μm) component of distal loess from the lower Mississippi River Valley, and LRT dust from Africa. These parent materials can be characterized geochemically using trace elements that are immobile in the soil‐forming environment. Results indicate that local volcanic bedrock on Bermuda has Sc‐Th‐La, Cr‐Ta‐Nd, and Eu/Eu*, LaN/YbN, GdN/YbNthat can be distinguished from African dust and lower Mississippi River valley loess. Bermuda soils have Sc‐Th‐La, Cr‐Ta‐Nd, and Eu/Eu*, LaN/YbN, GdN/YbN that indicate derivation from a combination of LRT dust from Africa and local volcanic bedrock. Our results indicate that soils on islands in a very broad latitudinal belt of the western Atlantic margin have been influenced by African LRT dust inputs over much of the past ∼500 ka.
The effect of hydrographs on bed load transport and bed sediment spatial arrangement
Authors: Mao Luca
Published: July 2012

Field measurements of sediment transport in gravel bed rivers often reveal hysteretic effects due to differences in sediment availability between the rising and falling limbs of a flood hydrograph. However, only a small number of flume studies have analyzed the dynamics of sediment transport during hydrographs. Three types of stepped hydrographs with contrasting durations and magnitudes are simulated here under sediment recirculation conditions. Bed load transport rate and grain size have been measured continuously. The dynamic behavior of the surface armor layer has been explored by analyzing digital photographs and laser scanner surveys of the bed surface taken during hydrographs. The results indicate that sediment transport during the falling limb was lower than during the rising limb in all of the three types of hydrographs. This reduction is more evident for the low‐magnitude hydrographs. The grain size of the bed remained virtually constant throughout the hydrographs but the grain size of transported sediments exhibited a counterclockwise hysteresis. Also, a significant increase in the reference shear stress for sediment entrainment was measured during the falling limb of hydrographs. Additionally, a detailed analysis of partial transport dynamics of the bed surface sediments reveals a reduction in sediment mobility during the falling limb of the hydrographs. The difference in sediment entrainment and transport before and after the peak of the hydrographs appears to be caused by a change in the organization of the surface sediments. An analysis of detailed laser scan bed surveys reveals a phase of bed restructuring (lower vertical roughness, clast rearrangement) during the falling limb of hydrographs. Consequently, changes in the degree of organization and complexity of the bed surface are likely the cause of the reduced mobility of sediments, and thus of the reduced sediment transport rate, during the falling limb of the hydrographs.
Rapid vegetation redistribution in Southern California during the early 2000s drought
Authors: Fellows Aaron W. , Goulden Michael L.
Published: July 2012

Climate change in semi‐arid, midlatitude mountain environments is expected to shift the spatial patterns of temperature, water availability, and vegetation upslope. Vegetation growing near its low‐elevation range limit may prove especially vulnerable to mortality and decline. We investigated the altitudinal pattern of conifer mortality that occurred from 2002 to 2004 in Southern California's San Jacinto Mountains. We found that conifer mortality was focused in the lower portion of the midmontane conifer range, which drove the midmontane conifer distribution upslope. We investigated past reports of conifer mortality in Southern California by searching historical newspaper accounts. We found evidence of previous episodes of conifer mortality that coincided with past droughts, and which may have caused vegetation redistribution in the past. We interpret the early 2000s mortality and associated vegetation redistribution as a response to natural decadal to centennial climate variability. Moreover, we hypothesize this response mode will dominate the early impact of global climate change on semi‐arid forest, which, in turn, may complicate efforts to distinguish between ecological changes attributable to natural climate variability and those attributable to global climate change.
Deglacial variability of Antarctic Intermediate Water penetration into the North Atlantic from authigenic neodymium isotope ratios
Authors: Xie Ruifang C. , Marcantonio Franco , Schmidt Matthew W.
Published: July 2012

Understanding intermediate water circulation across the last deglacial is critical in assessing the role of oceanic heat transport associated with Atlantic Meridional Overturning Circulation variability across abrupt climate events. However, the links between intermediate water circulation and abrupt climate events such as the Younger Dryas (YD) and Heinrich Event 1 (H1) are still poorly constrained. Here, we reconstruct changes in Antarctic Intermediate Water (AAIW) circulation in the subtropical North Atlantic over the past 25 kyr by measuring authigenic neodymium isotope ratios in sediments from two sites in the Florida Straits. Our authigenic Nd isotope records suggest that there was little to no penetration of AAIW into the subtropical North Atlantic during the YD and H1. Variations in the northward penetration of AAIW into the Florida Straits documented in our authigenic Nd isotope record are synchronous with multiple climatic archives, including the Greenland ice core δ18O record, the Cariaco Basin atmosphere Δ14C reconstruction, the Bermuda Rise sedimentary Pa/Th record, and nutrient and stable isotope data from the tropical North Atlantic. The synchroneity of our Nd records with multiple climatic archives suggests a tight connection between AAIW variability and high‐latitude North Atlantic climate change.
Visualization of Altered Neurovascular Coupling in Chronic Stroke Patients using Multimodal Functional MRI
Authors: Blicher Jakob U , Stagg Charlotte J , O'Shea Jacinta , Østergaard Leif , MacIntosh Bradley J , Johansen-Berg Heidi , Jezzard Peter , Donahue Manus J
Published: July 2012

Evaluation of cortical reorganization in chronic stroke patients requires methods to accurately localize regions of neuronal activity. Blood oxygenation level-dependent ( BOLD) functional magnetic resonance imaging (fMRI) is frequently employed; however, BOLD contrast depends on specific coupling relationships between the cerebral metabolic rate of oxygen ( CMRO2), cerebral blood flow ( CBF), and volume ( CBV), which may not exist following stroke. The aim of this study was to understand whether CSF-weighted ( CBFw) and CSV-weighted ( CBVw) fMRI could be used in sequence with BOLD to characterize neurovascular coupling mechanisms poststroke. Chronic stroke patients ( n = 11) with motor impairment and age-matched controls ( n = 11) performed four sets of unilateral motor tasks (60 seconds/30 seconds off/on) during CBFw, CBVw, and BOLD fMRI acquisition. While control participants elicited mean BOLD, CBFw, and CBVw responses in motor cortex ( P < 0.01), patients showed only mean changes in CBF ( P < 0.01) and CBV ( P < 0.01), but absent mean BOLD responses ( P = 0.20). BOLD intersubject variability was consistent with differing coupling indices between CBF, CBV, and CMRO2. Thus, CBFw and/or CBVw fMRI may provide crucial information not apparent from BOLD in these patients. A table is provided outlining distinct vascular and metabolic uncoupling possibilities that elicit different BOLD responses, and the strengths and limitations of the multimodal protocol are summarized.
A Guide for Enhancing Patient and Caregiver Communication
Authors: Vermilya Sally , Stevens Lizbeth Curme
Published: July 2012

We designed a tool to promote communication between an aphasic patient and her caregivers in an inpatient rehabilitation setting. We developed this tool, inspired by the mandatory swallowing guides hospitals post within 24 hours of a patient's admittance, using the Functional Independence Measure (FIM) score sheet relative to receptive and expressive communication abilities. We developed a guide in response to weekly patient staffings that resulted in information not being shared about individuals admitted after the staffing day. The visual display, which we placed adjacent to the patient's bed, fostered improved communication between the patient, caregivers, and family. This tool may be important for professionals in meeting requirements of the new standards for hospitals and skilled nursing facilities by The Joint Commission (The Joint Commission, 2010). We discuss the implications for its use relative to patients in various settings.
AAC Text Messaging
Authors: Williams Michael , Beukelman David , Ullman Cara
Published: July 2012

Text messaging is becoming an increasing popular social networking strategy. More than 80% of American adults have cell phones, three-quarters of them send and receive text messages. People who rely on AAC are also finding texting an efficient, asynchronous way to communicate. In this report, Michael Williams discusses his use of texting. We also introduce core vocabulary resources for AAC texting.
A Review of 21 iPad Applications for Augmentative and Alternative Communication Purposes
Authors: Alliano Ashley , Herriger Kimberly , Koutsoftas Anthony D. , Bartolotta Theresa E.
Published: July 2012

Using the iPad tablet for Augmentative and Alternative Communication (AAC) purposes can facilitate many communicative needs, is cost-effective, and is socially acceptable. Many individuals with communication difficulties can use iPad applications (apps) to augment communication, provide an alternative form of communication, or target receptive and expressive language goals. In this paper, we will review a collection of iPad apps that can be used to address a variety of receptive and expressive communication needs. Based on recommendations from Gosnell, Costello, and Shane (2011), we describe the features of 21 apps that can serve as a reference guide for speech-language pathologists.

We systematically identified 21 apps that use symbols only, symbols and text-to-speech, and text-to-speech only. We provide descriptions of the purpose of each app, along with the following feature descriptions: speech settings, representation, display, feedback features, rate enhancement, access, motor competencies, and cost.

In this review, we describe these apps and how individuals with complex communication needs can use them for a variety of communication purposes and to target a variety of treatment goals. We present information in a user-friendly table format that clinicians can use as a reference guide.
Supervision: Facilitating the Transition From Classroom to Clinic: Strategies and Methods
Authors: Moran Michael J. , Phillips Daniel , Zylla-Jones Elissa
Published: July 2012

In this article, the authors describe 14 strategies that may be incorporated into clinical education programs in speech-language pathology in order to help students make a smooth transition from the classroom to on- and off-campus clinical practicum. The strategies are divided into three categories: strategies for the classroom; strategies for the clinic; and strategies to facilitate coordination among academic faculty, clinical faculty, and external preceptors. The suggestions are drawn from the authors’ experience as well as from existing clinical literature.
Iatrogenic Oculocardiac Reflex in a Patient with Head Injury
Authors: Stathopoulos Panagiotis , Mezitis Michael , Kostakis George , Rallis George
Published: July 2012

A 16-year-old girl with a history of a recent fall from the third floor was transferred to the emergency room. On presentation, the patient, who had sustained multiple facial fractures, was in clinical shock with a blood pressure 80/40 mm Hg, heart rate 130/min, tachypnea (>30/min), PO2 50 mm Hg, and SO2 82%, and she was intubated for airway protection. Severe nasal hemorrhage was detected (hematocrit: 22%), therefore a bilateral anteroposterior balloon nasal catheter was inserted and inflated with air. Bleeding was controlled. A few minutes later, her heart rate dropped to 40/min. Atropine was administered intravenously and the rate increased to 60/min. Computed tomography of the head revealed brain and subarachnoid hemorrhage, multiple fractures of the facial skeleton, and a round foreign body, full of air, compressing the left eye. The medial wall and the floor of the ipsilateral orbit were also fractured, establishing a naso-orbital communication. The left catheter was immediately removed. Heart rate was restored to normal. Facial fractures were addressed surgically. Patient's vision is intact.
On the precision of quasi steady state assumptions in stochastic dynamics
Authors: Agarwal Animesh , Adams Rhys , Castellani Gastone C. , Shouval Harel Z.
Published: July 2012

Many biochemical networks have complex multidimensional dynamics and there is a long history of methods that have been used for dimensionality reduction for such reaction networks. Usually a deterministic mass action approach is used; however, in small volumes, there are significant fluctuations from the mean which the mass action approach cannot capture. In such cases stochastic simulation methods should be used. In this paper, we evaluate the applicability of one such dimensionality reduction method, the quasi-steady state approximation (QSSA) [L. Menten and M. Michaelis, “Die kinetik der invertinwirkung,” Biochem. Z 49, 333369 (1913)] for dimensionality reduction in case of stochastic dynamics. First, the applicability of QSSA approach is evaluated for a canonical system of enzyme reactions. Application of QSSA to such a reaction system in a deterministic setting leads to Michaelis-Menten reduced kinetics which can be used to derive the equilibrium concentrations of the reaction species. In the case of stochastic simulations, however, the steady state is characterized by fluctuations around the mean equilibrium concentration. Our analysis shows that a QSSA based approach for dimensionality reduction captures well the mean of the distribution as obtained from a full dimensional simulation but fails to accurately capture the distribution around that mean. Moreover, the QSSA approximation is not unique. We have then extended the analysis to a simple bistable biochemical network model proposed to account for the stability of synaptic efficacies; the substrate of learning and memory [J. E. Lisman, “A mechanism of memory storage insensitive to molecular turnover: A bistable autophosphorylating kinase,” Proc. Natl. Acad. Sci. U.S.A. 82, 3055–3057 (1985)]10.1073/pnas.82.9.3055. Our analysis shows that a QSSA based dimensionality reduction method results in errors as big as two orders of magnitude in predicting the residence times in the two stable states.
Advances in compact proton spectrometers for inertial-confinement fusion and plasma nuclear science
Authors: Seguin F. H. , Sinenian N. , Rosenberg M. , Zylstra A. , Manuel M. J.-E. , Sio H. , Waugh C. , Rinderknecht H. G. , Johnson M. Gatu , Frenje J. , Li C. K. , Petrasso R. , Sangster T. C. , Roberts S.
Published: July 2012

Compact wedge-range-filter proton spectrometers cover proton energies ∼3–20 MeV. They have been used at the OMEGA laser facility for more than a decade for measuring spectra of primary D3He protons in D3He implosions, secondary D3He protons in DD implosions, and ablator protons in DT implosions; they are now being used also at the National Ignition Facility. The spectra are used to determine proton yields, shell areal density at shock-bang time and compression-bang time, fuel areal density, and implosion symmetry. There have been changes in fabrication and in analysis algorithms, resulting in a wider energy range, better accuracy and precision, and better robustness for survivability with indirect-drive inertial-confinement-fusion experiments.
The photonuclear neutron and gamma-ray backgrounds in the fast ignition experiment
Authors: Arikawa Y. , Nagai T. , Hosoda H. , Abe Y. , Kojima S. , Fujioka S. , Sarukura N. , Nakai M. , Shiraga H. , Ozaki T. , Azechi H.
Published: July 2012

In the fast-ignition scheme, very hard x-rays (hereinafter referred to as γ-rays) are generated by Bremsstrahlung radiation from fast electrons. Significant backgrounds were observed around the deuterium–deuterium fusion neutron signals in the experiment in 2010. In this paper the backgrounds were studied in detail, based on Monte Carlo simulations, and they were confirmed to be γ-rays from the target, scattered γ-rays from the experimental bay walls (γ′-rays), and neutrons generated by (γ, n) reactions in either the target vacuum chamber or the diagnostic instruments (γ-n neutrons).
Mechanism of molecular orientation by single-cycle pulses
Authors: Ortigoso Juan
Published: July 2012

Significant molecular orientation can be achieved by time-symmetric single-cycle pulses of zero area, in the THz region. We show that in spite of the existence of a combined time-space symmetry operation, not only large peak instantaneous orientations, but also nonzero time-average orientations, over a rotational period, can be obtained. We show that this unexpected phenomenon is due to interferences among eigenstates of the time-evolution operator, as was described previously for transport phenomena in quantum ratchets. This mechanism also works for appropriate sequences of identical pulses, spanning a rotational period. This fact can be used to obtain a net average molecular orientation regardless of the magnitude of the rotational constant.
A computationally efficacious free-energy functional for studies of inhomogeneous liquid water
Authors: Sundararaman Ravishankar , Letchworth-Weaver Kendra , Arias T. A.
Published: July 2012

We present an accurate equation of state for water based on a simple microscopic Hamiltonian, with only four parameters that are well-constrained by bulk experimental data. With one additional parameter for the range of interaction, this model yields a computationally efficient free-energy functional for inhomogeneous water, which captures short-ranged correlations, cavitation energies, and, with suitable long-range corrections, the nonlinear dielectric response of water, making it an excellent candidate for the studies of mesoscale water and for use in ab initio solvation methods.
Mechanism for atmosphere dependence of laser damage morphology in HfO2/SiO2 high reflective films
Authors: Pu Yunti , Ma Ping , Chen Songlin , Zhu Jiliang , Wang Gang , Pan Feng , Sun Ping , Zhu Xiaohong , Zhu Jianguo , Xiao Dingquan
Published: July 2012

We show in this paper single-shot and multi-shot laser-induced damage thresholds (LIDTs) of HfO2/SiO2 high reflective films (the reflectance = 99.9%) are affected by the presence of a water layer absorbed on the surface of the porous films. When the water layer was removed with the process of pumping, the single-shot LIDT measured in vacuum dropped to ∼48% of that measured in air, while the multi-shot LIDT in vacuum dropped to ∼47% of its atmospheric value for the high reflective films. Typical damage micrographs of the films in air and in vacuum were obtained, showing distinct damage morphologies. Such atmosphere dependence of the laser damage morphology was found to originate from that formation of a water layer on the surface of porous films could cause an increase of horizontal thermal conductivity and a reduction of vertical thermal conductivity. Moreover, laser-induced periodic ripple damages in air were found in the SiO2 layer from the micrographs. A model of deformation kinematics was used to illustrate the occurrence of the periodic ripple damage, showing that it could be attributed to a contraction of the HfO2 layer under irradiation by the 5-ns laser pulses in air.
Surface roughness and magnetic properties of L1 FePt films on MgO/CrRu/TiN
Authors: Kim Chang Soo , Choi Dooho , Chung Suk , Wise Adam , Dang Ying Yi , Kryder Mark H.
Published: July 2012

Processes for making well ordered L10 FePt thin films with root-mean-square surface roughness close to 0.4 nm, perpendicular anisotropy greater than 5 kOe and perpendicular squareness near 1 using a deposition temperature of 390 °C have been developed. In this study, we focused on reducing the ordering temperature and smoothness of L10 FePt films, while achieving good perpendicular magnetic properties by using MgO/CrRu/TiN or MgO/CrRu/Pt seed layers on Si/SiO2 substrates. It was found that the chemical ordering of L10 FePt films is strongly affected by the insertion of a sputtered MgO seed layer, and the CrRu (002) texture on a (002) textured MgO seed layer is substantially improved at high DC power. In order to prevent Cr diffusion, TiN and Pt films were inserted between the CrRu and FePt films. It was found that the smoothness, L10 FePt ordering, and perpendicular magnetic properties were strongly improved by the TiN barrier layer compared to the Pt barrier layer. Increased TiN thickness improved the perpendicular magnetic anisotropy due to the reduced lattice misfit between the CrRu and L10 FePt films.
Phase-shifting interferometer using a frequency-tunable diode laser calibrated by an optical frequency comb
Authors: Wu Xuejian , Zhang Jitao , Wei Haoyun , Li Yan
Published: July 2012

We present a phase-shifting interferometer based on a frequency-tunable diode laser calibrated by an optical frequency comb and the Carré algorithm. By use of the frequency control strategies of locking the diode laser to different comb modes and scanning the repetition rate, an arbitrary single optical frequency synthesizer is obtained. The relative laser frequency uncertainty is 5.7 × 10−12 for 1 s averaging time with tracing to an Rb clock and accurate phase steps are achieved by optical frequency tuning. The surface topography of a standard sphere is measured by this phase-shifting interferometer based on a flat reference. The phase measurement repeatability is λ/200. With this technique, phase measurement uncertainties from the laser frequency and phase steps are negligible.
Electric and magnetic properties of La0.67Sr0.33MnO3 thin films with a metal-insulator crossover behavior
Authors: Sun Y. H. , Zhao Y. G. , Zhu M. H. , Xie B. T. , Wu W. B.
Published: July 2012

The electric and magnetic properties of 10 nm thick La0.67Sr0.33MnO3 films grown on LaAlO3 substrates have been investigated. Structural analysis shows the high quality of the films. With decreasing temperature, the resistivity of the samples increases and shows a peak at about 90 K, followed by a resistivity minimum at about 30 K, manifesting a metal-insulator crossover behavior, which is quite different from the transport behaviors of thicker or thinner films. Both electric current and magnetic field can distinctly reduce the resistivity. Remarkable electroresistance under very low currents, strong resistive hysteresis, and exchange bias effect are observed at low temperatures. The results are discussed in terms of phase separation induced by compressive strain in the films.
Magnetised Kelvin-Helmholtz instability in the intermediate regime between subsonic and supersonic regimes
Authors: Henri P. , Califano F. , Faganello M. , Pegoraro F.
Published: July 2012

The understanding of the dynamics at play at the Earth’s Magnetopause, the boundary separating the Earth’s magnetosphere and the solar wind plasmas, is of primary importance for space plasma modeling. We focus our attention on the low latitude flank of the magnetosphere where the velocity shear between the magnetosheath and the magnetospheric plasmas is the energetic source of Kelvin-Helmholtz instability. On the shoulder of the resulting vortex chain, different secondary instabilities are at play depending on the local plasma parameters and compete with the vortex pairing process. Most important, secondary instabilities, among other magnetic reconnection, control the plasma mixing as well as the entry of solar wind plasma in the magnetosphere. We make use of a two-fluid model, including the Hall term and the electron mass in the generalized Ohm’s law, to study the 2D non-linear evolution of the Kelvin-Helmholtz instability at the magnetosheath–magnetosphere interface, in the intermediate regime between subsonic and supersonic regimes. We study the saturation mechanisms, depending on the density jump across the shear layer and the magnetic field strength in the plane. In the presence of a weak in-plane magnetic field, the dynamics of the Kelvin-Helmholtz rolled-up vortices self-consistently generates thin current sheets where reconnection instability eventually enables fast reconnection to develop. Such a system enables to study guide field multiple-island collisionless magnetic reconnection as embedded in a large-scale dynamic system, unlike the classical static, ad hoc reconnection setups. In this regime, reconnection is shown to inhibit the vortex pairing process. This study provides a clear example of nonlinear, cross-scale, collisionless plasma dynamics.
Current transport in nonpolar a-plane InN/GaN heterostructures Schottky junction
Authors: Rajpalke Mohana K. , Bhat Thirumaleshwara N. , Roul Basanta , Kumar Mahesh , Krupanidhi S. B.
Published: July 2012

The temperature dependent current transport properties of nonpolar a-plane (112¯0) InN/GaN heterostructure Schottky junction were investigated. The barrier height (ϕb) and ideally factor (η) estimated from the thermionic emission (TE) model were found to be temperature dependent in nature. The conventional Richardson plot of the ln(Is/T2) versus 1/kT has two regions: the first region (150–300 K) and the second region (350–500 K). The values of Richardson constant (A*) obtained from this plot are found to be lower than the theoretical value of n-type GaN. The variation in the barrier heights was explained by a double Gaussian distribution with mean barrier height values (ϕb¯) of 1.17 and 0.69 eV with standard deviation (σs) of 0.17 and 0.098 V, respectively. The modified Richardson plot in the temperature range 350–500 K gives the Richardson constant which is close to the theoretical value of n-type GaN. Hence, the current mechanism is explained by TE by assuming the Gaussian distribution of barrier height. At low temperature 150–300 K, the absence of temperature dependent tunneling parameters indicates the tunneling assisted current transport mechanism.
Magnetocaloric and transport study of poly- and nanocrystalline composite manganites La0.7Ca0.3MnO3/La0.8Sr0.2MnO3
Authors: Pękała M. , Pękała K. , Drozd V. , Staszkiewicz K. , Fagnard J.-F. , Vanderbemden P.
Published: July 2012

Magnetocaloric and transport properties are reported for novel poly- and nanocrystalline double composite manganites, La0.8Sr0.2MnO3/La0.7Ca0.3MnO3, prepared by the sol-gel method. Magnetic field dependence of magnetic entropy change is found to be stronger for the nano- than the polycrystalline composite. The remarkable broadening of the temperature interval, where the magnetocaloric effect occurs in poly- and nanocrystalline composites, causes the relative cooling power (RCP(S)) of the nanocrystalline composite to be reduced by only 10% compared to the Sr based polycrystalline phase. The RCP(S) of the polycrystalline composite becomes remarkably enhanced. The low temperature magnetoresistance is enhanced by 5% for the nanostructured composite.