bluuebunny/crossref_metadata_2025 huggingface dataset:
Threading dislocation density reduction in two‐stage growth of GaN layers
Authors: Bougrov V. E. , Odnoblyudov M. A. , Romanov A. E. , Lang T. , Konstantinov O. V.
Published: February 2006

A theoretical approach is proposed to reduce the density of threading dislocations (TDs) in (0001) oriented growth of GaN layers. The approach can be realized by repeated stages of growth surface roughening (stage I) and flattening (stage II). Fundamentals of the approach include the formation of a dislocation redirection layer with inclined TDs at stage I and enhanced reactivity among inclined TDs in a dislocation reaction layer at stage II. A reaction‐kinetics model is applied for the quantitative prediction of TD density reduction which can be achieved as a result of the two‐stage growth technique. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Partition Coefficient Kow of Benzene, Ethanol and Aniline in Benzene‐ethanol and Aniline‐benzene Mixtures and Coefficient of Distribution Kmix of these Mixtures
Authors: Rucki M. , Tichý M.
Published: February 2006

The study related to partition coefficients between n‐octanol and water Kow of compounds in binary mixtures benzene‐ethanol and benzene‐aniline was carried out. Partition coefficients of benzene, aniline and ethanol for different values of molar ratio of benzene and different total concentration of compounds in the mixtures benzene‐ethanol and benzene‐aniline were determined. Coefficient of distribution Kmix was determined for both mixtures. In benzene‐ethanol mixture collected results show statistically significant deviations the Kow of benzene from values for pure compound. For ethanol, there are no statistically significant deviations from values for pure compound. But also there are some trends of changes of Kow. In benzene‐aniline mixture collected results show statistically significant deviations of the Kow of benzene and aniline from values for pure compounds. Changes of Kow were used for explanation of acute toxicity of binary mixtures benzene‐ethanol and aniline‐benzene.
Robust locally testable codes and products of codes
Authors: Ben‐Sasson Eli , Sudan Madhu
Published: February 2006

We continue the investigation of locally testable codes, i.e., error‐correcting codes for which membership of a given word in the code can be tested probabilistically by examining it in very few locations. We give two general results on local testability: First, motivated by the recently proposed notion of robust probabilistically checkable proofs, we introduce the notion of robust local testability of codes. We relate this notion to a product of codes introduced by Tanner and show a very simple composition lemma for this notion. Next, we show that codes built by tensor products can be tested robustly and somewhat locally by applying a variant of a test and proof technique introduced by Raz and Safra in the context of testing low‐degree multivariate polynomials (which are a special case of tensor codes). Combining these two results gives us a generic construction of codes of inverse polynomial rate that are testable with poly‐logarithmically many queries. We note that these locally testable tensor codes can be obtained from any linear error correcting code with good distance. Previous results on local testability, albeit much stronger quantitatively, rely heavily on algebraic properties of the underlying codes. © 2006 Wiley Periodicals, Inc. Random Struct. Alg., 2006
Diagnosis, characterization and outcome of congenitally corrected transposition of the great arteries in the fetus: a multicenter series of 30 cases
Authors: Paladini D. , Volpe P. , Marasini M. , Russo M. G. , Vassallo M. , Gentile M. , Calabrò R.
Published: February 2006

Objective

To describe the anatomy, associated anomalies and outcome of 30 cases of congenitally corrected transposition of the great arteries (ccTGA) detected prenatally.

Methods

This was a retrospective observational study of the 30 cases of ccTGA confirmed at autopsy or postnatal echocardiography seen at one of three referral centers from 1994 to 2003. The following data were considered: gestational age at diagnosis, cardiac anatomy, associated cardiac and extracardiac anomalies and fetoneonatal outcome. All fetuses underwent fetal echocardiography and a detailed anomaly scan, with follow‐up scans at 3–4‐week intervals until delivery. The diagnosis was confirmed at autopsy or after delivery. Follow‐up data were retrieved from the clinical files of the patients.

Results

The mean gestational age at diagnosis was 25.5 weeks. Intracardiac defects associated with the ccTGA included a ventricular septal defect in 21 cases, pulmonary outflow obstruction in 12 cases, an abnormal tricuspid valve in 10 cases, ventricular hypoplasia in five cases and dextro/mesocardia in five cases. The karyotype was normal in all 24 newborns, and unknown in the cases which resulted in termination of pregnancy (n = 5) or intrauterine death (n = 1). There were associated extracardiac anomalies in four cases only. Three of the four cases of atrioventricular block (AV block) developed in the third trimester, while the fourth appeared after birth. There were nine deaths (five terminations, two perinatal deaths and two infant deaths). The remaining 21 (70%) newborns were alive at a median follow‐up time of 32 months, 11 of them after various surgical procedures.

Conclusions

Our data suggest that in fetuses with ccTGA the risk of chromosomal and extracardiac anomalies is low, in accordance with postnatal data. The spectrum of associated cardiac lesions is consistent with that reported in the pediatric literature. These data may be of use during prenatal counseling since no figures regarding survival and/or outcome of ccTGA in the fetus have been reported so far. Copyright © 2006 ISUOG. Published by John Wiley & Sons, Ltd.
Isolated ventricular septal defects detected by color Doppler imaging: evolution during fetal and first year of postnatal life
Authors: Axt‐Fliedner R. , Schwarze A. , Smrcek J. , Germer U. , Krapp M. , Gembruch U.
Published: February 2006

Objective

To evaluate the development during gestation and up to 1 year postnatally of isolated small ventricular septal defects (VSDs) not visible by gray‐scale imaging and detected only on color Doppler fetal echocardiography.

Methods

This was a retrospective analysis of 146 fetuses with isolated VSDs detectable only on color Doppler echocardiography. Complete sequential gray‐scale, color Doppler and spectral Doppler examination of the fetal heart were performed. The following variables were documented: site of the VSD, presence of extracardiac or chromosomal anomalies, outcome of the pregnancy and evolution of the defect up to 1 year postnatally.

Results

A total of 113 fetuses reached their first year of postnatal life, 23 pregnancies were terminated, there were three stillbirths/neonatal deaths, and seven were lost to follow‐up. It was observed that 32.7% (n = 37) of all defects in neonates alive after 1 year closed in utero, 44.3% (n = 50) of defects closed spontaneously within the first postnatal year, and 23.0% (n = 26) of defects did not close. In all, a comparable number of perimembranous and muscular septal defects closed spontaneously in utero and during the first year of postnatal life. Among 35 fetuses with extracardiac anomalies 51.4% (n = 18) were euploid.

Conclusion

Small VSDs, detectable only by color Doppler echocardiography, show a high spontaneous intrauterine and postnatal closure rate. These findings might be of value for prenatal parental counseling. Copyright © 2006 ISUOG. Published by John Wiley & Sons, Ltd.
Surgical Outcomes Research Based on Administrative Data: Inferior or Complementary to Prospective Randomized Clinical Trials?
Authors: Guller Ulrich
Published: February 2006

The importance of surgical research has gained new prominence over the past decades as the relevance of well designed and well conducted studies has become increasingly evident. There are two basic but diametrically different methods of conducting research: the prospective randomized clinical trial and the retrospective surgical outcomes study based on administrative data. Administrative databases contain data that were initially collected for purposes other than scientific research. Whereas the prospective randomized clinical trial is familiar to most surgeons, surgical outcomes research based on administrative data constitutes a genre of investigation that is often unfamiliar to and even disparaged by the surgical community. In the present article, the strengths and weaknesses of both prospective randomized clinical trials and retrospective surgical outcomes research are discussed. Specifically, the advantages and limitations of investigations based on large administrative databases are outlined. Because both study designs play an important role in surgical research, carefully designed and implemented surgical outcomes research based on administrative data should be viewed as being complementary and not inferior to prospective randomized clinical trials.
Clinicopathologic Comparison of Siewert Type II and III Adenocarcinomas of the Gastroesophageal Junction
Authors: Yuasa Norihiro , Miyake Hideo , Yamada Tatsuharu , Ebata Tomoki , Nimura Yuji , Hattori Tatsuo
Published: February 2006

Background

Since Misumi et al. and Siewert proposed a new classification for carcinoma of the gastroesophageal junction (GEJ), few surgical studies using these criteria have been reported from Eastern countries. Siewert type II adenocarcinomas are managed using general rules for either gastric or esophageal cancer. We set out to determine whether type II adenocarcinoma is a distinct clinical entity requiring a more specific treatment plan.

Methods

Among 125 Japanese patients who underwent resection of adenocarcinoma of the GEJ (type I, 2; type II, 44; type III, 79), 101 who underwent R0 resections (type II, 40; type III, 61) were analyzed to evaluate surgical results and compare clinicopathologic factors.

Results

Barrett’s epithelium was recognized in two patients with type II adenocarcinoma. Type II differed significantly from type III in higher prevalence of Borrmann macroscopic type 2, more frequent lymph node metastasis (58% vs. 34%), higher metastatic rate to lower mediastinal lymph nodes (13%), increased risk of hepatic recurrence, and lower 5‐year survival after R0 resection (67.4% vs. 87.1%).

Conclusions

Clinicopathologic differences were evident between type II and III adenocarcinomas. Siewert type II adenocarcinoma differs sufficiently to be considered a clinical entity distinct and independent from type III.
Enhanced myocardial cathepsin B expression in patients with dilated cardiomyopathy
Authors: Ge Junbo , Zhao Gang , Chen Ruizhen , Li Shuangjie , Wang Shijun , Zhang Xingang , Zhuang Yamin , Du Jiuzhong , Yu Xiaohua , Li Gaoping , Yang Yingzhen
Published: February 2006

Objective

Cathepsin B is a prominent lysosomal protease and is involved in apoptosis as well as degradation of myofibrillar proteins in myocardial infarction. The aim of this study was to investigate myocardial cathepsin B expression in failing and non‐failing human hearts.

Methods:

Tissue samples were taken from transplanted left ventricles from 20 patients with dilated cardiomyopathy and 5 non‐failing donor hearts that could not be transplanted for technical reasons. Myocardial cathepsin B expression was determined by immunohistochemistry, the reverse transcription–polymerase chain reaction (RT–PCR) and Western blotting. Apoptosis was assessed by TUNEL staining.

Results:

Positive cathepsin B staining was found in failing and non‐failing hearts. The expression of cathepsin B at mRNA and protein levels was significantly higher in failing hearts compared with non‐failing hearts. Correlation analysis revealed that cathepsin B at mRNA and protein levels negatively correlated with EF (r=0.66, p=0.002 and r=0.492, p=0.028, respectively) in patients with heart failure. The apoptotic index was 0.015±0.006 in failing hearts and 0.002±0.001 in non‐failing hearts (p<0.01).

Conclusion:

Increased myocardial expression of cathepsin B was found in patients with heart failure suggesting that cathepsin B might play a role in the genesis and development of heart failure.
Neotectonics of the SW Marmara region, NW Anatolia, Turkey
Authors: GÜRER ÖMER FEYZI , SANGU ERCAN , ÖZBURAN MUZAFFER
Published: February 2006

This study reports on the geometric and structural characteristics of the North Anatolian Fault Zone in the southwest Marmara region. The geometric and kinematic features of the faults in the region are described, based on field observations. In addition, the Neogene and Quaternary basin fill which occupies large areas in the region has been determined, and the tectonic regimes controlling these basins are explained. The neotectonic regime is also explained considering different deformation phases affecting the region. The N–S extension and E–W strike-slip have affected the region possibly since the latest Pliocene–Quaternary. Field observations show that these extensional tectonics around the south Marmara region are related to right strike-slip on the E–W North Anatolian fault zone and the N–S Aegean extensional system. The faults in this zone trend approximately E–W in the eastern part of the region and NE–SW towards the west of the region, indicating that they accommodate rotation in addition to differential movement between adjacent blocks.
‘Surgical skills box’: a new training aid for surgical trainees
Authors: Carr E R M , Benjamin E
Published: February 2006

Introduction: Surgical trainees now receive less operating experience with the reduction in junior doctor hours.

Design: We designed a simple, portable, versatile ‘surgical skills box’ which allowed surgical trainees to practise vascular anastomosis, suturing, tonsil ties, hand ties and grommet insertion.

Discussion: With surgical trainees now receiving reduced operating experience it is more important than ever for them to practise their surgical skills outside the operating theatre environment.
Multiple cervical bronchogenic cysts
Authors: Maung Kyaw Htin , Low Christopher , Knight Lindsey C , Cullinane Catherine J
Published: February 2006

Bronchogenic cysts are rare, benign, congenital lesions that occur as a result of aberrant development of the tracheobronchial tree during embryogenesis. They usually present during the first decade of life and are encountered predominantly within the mediastinum or the lung parenchyma. In a few instances, they appear within the neck mimicking a neoplasm and, depending on their size and site, may also cause acute upper respiratory obstruction. We describe a case of two cervical bronchogenic cysts adjacent to the larynx in a child who presented with a hoarse voice.
Patients' understanding of words used to describe lumps: a cross-sectional study
Authors: Chadha Neil K , Repanos Costa
Published: February 2006

Objectives: To explore the interpretation of words commonly used to describe lumps. Specific words were explored to assess their understandability and implication of threat to the patient.

Methods: A cross-sectional, questionnaire-based study was undertaken. Age, gender, level of education, employment and socio-economic group were determined. The questionnaire explored the following words: malignant, tumour, carcinoma, lymphoma, sarcoma, lipoma, lymph node, nodule, ganglion, benign, cyst and gland. Participants comprised 204 consecutive adult patients attending the ENT out-patient clinic at a Bristol teaching hospital.

Results: Patients found ‘malignant’ and ‘tumour’ the most threatening words and were most unsure of the meaning of ‘sarcoma’ and ‘lipoma’. Nineteen per cent (n = 37) thought a ‘benign’ lump was a cancer. Results did not significantly differ between demographic groups.

Conclusions: A significant misunderstanding of some words commonly used to describe lumps was found. This study provides important guidance on which terms to use and which to avoid in consultations with patients.
Papillary thyroid carcinoma with exuberant nodular fasciitis-like stroma: treatment outcome and prognosis
Authors: Basu S , Nair N , Shet T , Borges A M
Published: February 2006

Papillary thyroid carcinoma with nodular fasciitis-like stroma (PTC-NFS) is one of the extremely rare variants of papillary thyroid carcinoma. To date, the majority of reported cases have been published in the surgical pathology and cytopathology literature, addressing the diagnostic difficulties posed by the condition's extensive, reactive stromal proliferation. Because of the rarity of PTC-NFS among papillary thyroid carcinoma variants, it has been unexplored from a clinical viewpoint. A MEDLINE search on the clinical course, role of radioiodine, treatment outcome and long term follow up of this disease yielded no result.

We report the clinicoradiologic and histopathologic profile, together with post-treatment long term follow up, in a 35-year-old woman harbouring this rare entity. To the best of our knowledge, this is the first report of a five-year follow up of this rare variant of PTC following total thyroidectomy and radioiodine treatment. Our follow-up findings reiterate the disease's favourable clinical course when managed in the same manner as a classical, differentiated papillary carcinoma of the thyroid, akin to that predicted by the pathologists, and emphasize the importance of differentiating PTC-NFS as a separate entity from the papillary carcinoma variants with aggressive histology. Given the rarity of this condition, the experience gained from the present case is a useful addition to the current knowledge on disease prognostication and management.

A systematic review of the existing literature on PTC-NFS, including the case reported in the present paper, is also carried out, aiming to explore the patient characteristics and clinical behaviour pattern of this rare entity and to make appropriate recommendations on management strategy. The age of presentation ranges from 20 to 82 years, with a mean of 44.5 years. Female preponderance was observed, with a female to male ratio of 3[ratio ]1. No racial predilection was observed. Tumour size varied from 2 to 9 cm along its greatest diameter (mean = 4.3 cm). Metastasis to lymph nodes at presentation occurred in 25 per cent of cases. Metastasis to surrounding structures (e.g. parathyroid and skeletal muscle) was observed in 12.5 per cent. There have been no reports of pulmonary or skeletal metastasis at presentation.
Mantle dynamics beneath the East Pacific Rise at 17°S: Insights from the Mantle Electromagnetic and Tomography (MELT) experiment
Authors: Baba Kiyoshi , Chave Alan D. , Evans Rob L. , Hirth Greg , Mackie Randall L.
Published: February 2006

The electromagnetic data from the Mantle Electromagnetic and Tomography (MELT) experiment are inverted for a two‐dimensional transversely anisotropic conductivity structure that incorporates a correction for three‐dimensional topographic effects on the magnetotelluric responses. The model space allows for different conductivity values in the along‐strike, cross‐strike, and vertical directions, along with imposed constraints of model smoothness and closeness among the three directions. Anisotropic models provide a slightly better fit to the data for a given level of model smoothness and are more consistent with other geophysical and laboratory data. The preferred anisotropic model displays a resistive uppermost 60‐km‐thick mantle independent of plate age, except in the vicinity of the ridge crest. In most inversions, a vertically aligned sheet‐like conductor at the ridge crest is especially prominent in the vertical conductivity. Its presence suggests that the melt is more highly concentrated and connected in the vertical direction immediately beneath the rise axis. The melt zone is at least 100 km wide and is asymmetric, having a greater extent to the west. Off‐axis, and to the east of the ridge, the mantle is more conductive in the direction of plate spreading at depths greater than 60 km. The flat resistive‐conductive boundary at 60 km agrees well with the inferred depth of the dry solidus of peridotite, and the deeper conductive region is consistent with the preferred orientation of olivine inferred from seismic observations. This suggests that the uppermost 60 km represents the region of mantle that has undergone melting at the ridge and has been depleted of water (dissolved hydrogen). By contrast, the underlying mantle has retained a significant amount of water.
Fault reactivation and rift localization: Northeastern Gulf of Aden margin
Authors: Bellahsen N. , Fournier M. , d'Acremont E. , Leroy S. , Daniel J. M.
Published: February 2006

The Gulf of Aden and the Sheba spreading ridge (Gulf of Aden) forms the southern boundary of the Arabian Plate. Its orientation (075°E) and its kinematics (about 030°E divergence) are interpreted as the result of an oblique rifting. In this contribution, a field study in the northeastern Gulf of Aden allows us to confirm the Oligo‐Miocene synrift directions of extension and to precise the normal fault network geometry. The synrift extensions are 020°E and 160°E (possibly in this chronological order); the normal faults strike 070°E, 090°E, and 110°E. The results show that some characteristics are consistent with oblique rifting analogue models, while some others are not. Especially, fault reactivation of Mesozoic structures is shown to have occurred significantly at the beginning and during rifting. These data are therefore compared to analogue models of oblique reactivation, and this comparison demonstrates that fault reactivation played a key role during the early stage of the Gulf of Aden rifting. Finally, scenarios of the lithospheric evolution during the eastern Gulf of Aden opening (preexisting weaknesses in the lithosphere or not) are discussed to better constrain the deformation history of the northern margin. Especially, we show that rift localization processes may imply stress rotations through time.
Atmospheric potential oxygen: New observations and their implications for some atmospheric and oceanic models
Authors: Battle Mark , Fletcher Sara Mikaloff , Bender Michael L. , Keeling Ralph F. , Manning Andrew C. , Gruber Nicolas , Tans Pieter P. , Hendricks Melissa B. , Ho David T. , Simonds Caroline , Mika Robert , Paplawsky Bill
Published: February 2006

Measurements of atmospheric O2/N2 ratios and CO2 concentrations can be combined into a tracer known as atmospheric potential oxygen (APO ≈ O2/N2 + CO2) that is conservative with respect to terrestrial biological activity. Consequently, APO reflects primarily ocean biogeochemistry and atmospheric circulation. Building on the work of Stephens et al. (1998), we present a set of APO observations for the years 1996–2003 with unprecedented spatial coverage. Combining data from the Princeton and Scripps air sampling programs, the data set includes new observations collected from ships in the low‐latitude Pacific. The data show a smaller interhemispheric APO gradient than was observed in past studies, and different structure within the hemispheres. These differences appear to be due primarily to real changes in the APO field over time. The data also show a significant maximum in APO near the equator. Following the approach of Gruber et al. (2001), we compare these observations with predictions of APO generated from ocean O2 and CO2 flux fields and forward models of atmospheric transport. Our model predictions differ from those of earlier modeling studies, reflecting primarily the choice of atmospheric transport model (TM3 in this study). The model predictions show generally good agreement with the observations, matching the size of the interhemispheric gradient, the approximate amplitude and extent of the equatorial maximum, and the amplitude and phasing of the seasonal APO cycle at most stations. Room for improvement remains. The agreement in the interhemispheric gradient appears to be coincidental; over the last decade, the true APO gradient has evolved to a value that is consistent with our time‐independent model. In addition, the equatorial maximum is somewhat more pronounced in the data than the model. This may be due to overly vigorous model transport, or insufficient spatial resolution in the air‐sea fluxes used in our modeling effort. Finally, the seasonal cycles predicted by the model of atmospheric transport show evidence of an excessive seasonal rectifier in the Aleutian Islands and smaller problems elsewhere.
Western Caribbean sea surface temperatures during the late Quaternary
Authors: Schmidt Matthew W. , Vautravers Maryline J. , Spero Howard J.
Published: February 2006

Mg/Ca ratios in the planktonic foraminifera Globigerinoides ruber from Colombian Basin core ODP 999A suggest that Caribbean sea surface temperatures (SSTs) were from 2.1 to 2.7°C colder than the present during the last three glacial maximums. In comparison, faunal derived SSTs (SIMMAX method) show that August SSTs in the Caribbean varied <2°C over the past 360 kyr, whereas February SSTs varied between 21.0°C and 26.5°C. Changes in the Mg/Ca‐SST record contain a strong 23 kyr periodicity, suggesting the Mg/Ca‐SST record reflects a warm season weighted SST average rather than an annual mean SST. Combining several dissolution indices, we identify brief periods of decreased carbonate preservation in our record and show that MIS 11 stands out as the most intensive dissolution cycle in the Caribbean over the last 460 kyr. Comparison of Caribbean SST change with a similar estimate of tropical SST variability in the western Pacific over the past 360 kyr reveals shifts in the east‐west tropical SST gradient that are coeval with glacial‐interglacial climate change and consistent both with a southward migration of the glacial ITCZ and with a glacial El Niño‐like mode of tropical circulation.
Tomographic regionalization of crustal Lg Q in eastern Eurasia
Authors: Xie J. , Wu Z. , Liu R. , Schaff D. , Liu Y. , Liang J.
Published: February 2006

We measure Q of crustal Lg waves in eastern Eurasia using the reliable two‐station methods. More than 5,000 spectral ratios are collected over 594 interstation paths, and are used to determine values of Lg Q0 and η (Q at 1 Hz and its frequency dependence) over these paths. These values are used to derive tomographic models of laterally varying Q0 and η with resolutions between 4 and 10°. The Q0 model contains values that vary between 100 and 900. Q0 are the lowest in the Tibetan plateau, increase to moderate levels towards the east and north, and reach maxima in the Siberian and eastern Europe Cratons. Q0 values correlate well with regional tectonics. Most η values are between −0.14 and 0.50, with a mean of 0.18. These values are lower than those obtained previously using either an Lg coda Q method, or a method of simultaneous inversion of source spectra and Q.
Effect of carbonaceous aerosols on surface temperature in the mid twentieth century
Authors: Nagashima Tatsuya , Shiogama Hideo , Yokohata Tokuta , Takemura Toshihiko , Crooks Simon A. , Nozawa Toru
Published: February 2006

Simulations using a climate model are used to investigate the possible impact of increasing emissions of carbonaceous aerosols on near‐surface temperature in the mid‐20th century. The annual global mean near‐surface temperature change from the mid‐20th century onward is reasonably described by a model that is forced by changes in most of the known climate forcing agents including an increase in carbonaceous aerosols, though it can also be well reproduced without increases in carbonaceous aerosols. However, if we consider spatio‐temporal structure of the changes in the near‐surface temperature, an increase in carbonaceous aerosols is definitely required for the model to represent changes in the near‐surface temperature in the mid‐century, in particular, cooling trends in the tropical and subtropical continents. The significance of an increase in carbonaceous aerosols as an indispensable contributor to mid‐20th century temperature changes is confirmed with the use of an optimal fingerprinting methodology.
Atmospheric carbon dioxide in a less dusty world
Authors: Parekh P. , Dutkiewicz S. , Follows M. J. , Ito T.
Published: February 2006

The availability of iron exerts a significant control on primary production and the export of organic matter over large areas of the ocean, especially those far from land sources. We explore the regulation of the global soft tissue pump of carbon and atmospheric CO2 by the atmospheric delivery of iron in a three‐dimensional ocean circulation and biogeochemistry model. There is only a small change in atmospheric CO2 when the aeolian iron source is increased several fold but a significant increase in response to a reduction in the aeolian iron source. This strong asymmetry suggests a positive feedback, amplifying an increase in atmospheric CO2 if a warmer world is also less dusty.
A new view of the underside of Arctic sea ice
Authors: Wadhams P. , Wilkinson J. P. , McPhail S. D.
Published: February 2006

The Autosub‐II autonomous underwater vehicle (AUV), operating off NE Greenland in August 2004, obtained the first successful swath sonar measurements under sea ice, showing in unprecedented detail the three‐dimensional nature of the under‐ice surface. The vehicle, operated from RRS James Clark Ross, obtained more than 450 track‐km of under‐ice multibeam data. We show imagery from first‐ and multiyear ice, including young ridges, old hummocks and undeformed melting ice. In addition, we show how the combination of other on‐board sensors enabled the vehicle to obtain detailed information about seabed topography, water structure and current fields in an exploratory mode within a region which is seldom visited because of difficult year‐round ice conditions. This included identification of a new current regime in the Norske Trough.
High‐resolution global storm index: Dst versus SYM‐H
Authors: Wanliss James A. , Showalter Kristin M.
Published: February 2006

The classic view is that Dst and SYM‐H time series differ mainly due to the dissimilarity in the method to determine the base values. Dst and SYM‐H are both indices designed to measure the intensity of the storm time ring current. They are calculated in similar but not identical manners. Since SYM‐H has the distinct advantage of having 1‐min time resolution compared to the 1‐hour time resolution of Dst, it is worth determining if the differences introduced by using different ground stations and slightly different methods of baseline subtraction produce statistically significant differences in the values of the indices. We have examined data from these indices collected over more than 20 years to determine the extent to which Dst and SYM‐H are equivalent or different. We found that a simple combination of linear trends with a break at SYM‐H = −300 nT provides an excellent comparison with the Dst index. For quiet times and for small storms the deviations are typically no more than 10 nT. Moderate storms feature deviations typically only slightly more than 10 nT, and intense storms have deviations that are usually less than 20 nT. We conclude that the classic view is accurate and recommend that in future studies the SYM‐H index be used as a de facto high‐resolution Dst index.
Unusual topside ionospheric density response to the November 2003 superstorm
Authors: Yizengaw E. , Moldwin M. B. , Komjathy A. , Mannucci A. J.
Published: February 2006

We use observations from a variety of different ground‐ and space‐based instruments, including ionosonde, ground‐ and space‐based Global Positioning System (GPS) receivers, magnetometers, and solar wind data from the Advanced Composition Explorer (ACE), to examine the response of the ionospheric F2‐layer height during the November 2003 superstorm. We found that the topside ionosphere responded unusually to the 20 November 2003 severe storm compared to behavior observed in a number of previous storms. While ground‐based GPS receivers observed a large enhancement in dayside TEC, the low‐Earth orbiting (∼400 km) CHAMP satellite did not show any sign of dayside TEC enhancement. The real‐time vertical density profiles, constructed from ground‐based GPS TEC using a tomographic reconstruction technique, clearly revealed that the ionospheric F2‐layer peak height had been depressed down to lower altitudes. Ionospheric F‐layer peak height (hmF2) from the nearby ionosonde stations over Europe also showed that the dayside F2‐layer peak height was below 350 km, which is below the orbiting height of CHAMP. The vertical E × B drift (estimated from ground‐based magnetometer equatorial electrojet delta H) showed strong dayside downward drifts, which may be due to the ionospheric disturbance dynamo electric field produced by the large amount of energy dissipation into high‐latitude regions. This storm demonstrates that data from LEO satellites varies widely among different superstorms.
Cross‐scale coupling‐induced intermittency near interplanetary shocks
Authors: Vörös Z. , Leubner M. P. , Baumjohann W.
Published: February 2006

Several approaches exist to address the problem of intermittency in solar wind turbulence. The traditional explanation based on spectral transfer of energy between separated scales through sequential steps within a cascade can elucidate scalings and intermittent emergence of small‐scale dissipative structures. A recent point of view connects intermittency mainly with the occurrence of discontinuities and interaction of flux tube‐like coherent structures. In this paper we analyze the interrelationship between skewness and kurtosis near interplanetary shocks. On the basis of a comparison of our results with the behavior of skewness and kurtosis in laboratory experiments and numerical simulations we show that large‐scale boundaries and/or scalar gradient fields imposed on solar wind turbulence can lead to a local increase of small‐scale intermittency via direct coupling between separated scales. As each scenario is supported by experiments, they represent a complementary way of looking at intermittency.
Quantitative analysis of surface coseismic faulting and postseismic creep accompanying the 2003, Mw = 6.5, Chengkung earthquake in eastern Taiwan
Authors: Lee Jian‐Cheng , Chu Hao‐Tsu , Angelier Jacques , Hu Jyr‐Ching , Chen Horng‐Yue , Yu Shui‐Beih
Published: February 2006

On the basis of field observations and geodetic measurements we analyzed coseismic and postseismic deformation of the 2003, Mw = 6.5, Chengkung earthquake across the rupture trace of the Chihshang fault, which lies along the suture zone between the Philippine Sea plate and the Eurasian plate in eastern Taiwan. At three of our investigation sites along the Chihshang fault the earthquake deformation was exhibited by fresh fractures within the 150‐ to 200‐m‐wide surface fault zone, reactivating preexisting fractures in most cases. In addition to daily recorded creep meter data, geodetic measurements, including leveling, distance‐and‐angle electronic distance meters, and GPS measurements, were carried out during surveys 20–25 days before, 20–25 days after, and 120–125 days after the earthquake. The near–fault surface deformation is mainly characterized by anticlinal folding in the hanging wall and minor gentle synclinal folding in the footwall. The geodetic data show that within our 150‐ to 250‐m‐wide networks the coseismic deformation of the main shock produced only about 1–2 cm of horizontal shortening and vertical offset across the fault zone. A larger additional displacement of about 7–9 cm for both the horizontal shortening and the vertical offset occurred as postseismic creep during the 120–125 days following the main shock. We interpret the predominant folding and the rather large postseismic creep as a result of strong velocity strengthening along the fault plane near the surface, which caused locking or coupling effect during the coseismic rupturing. The depth of locked segment, along which the coseismic and postseismic slip decreased dramatically upward, is estimated to be 25–100 m, depending on the site. We interpreted the velocity strengthening and coupling effect at the shallow level as viscoelastic behavior of unconsolidated deposits in the footwall and mélange mudstone in the hanging wall. By incorporating far‐fault continuous GPS data, it was found that minor but significant deformation occurred outside of the surface ruptures zone of the Chihshang fault. In addition, a possible back thrust or back fold might have occurred in the hanging wall. We note that the Chengkung earthquake occurred during the dry season. This is consistent with the fact that the mechanical coupling of the fault at shallow depth is higher during drier periods, inferred from the previous seasonal creep data. At outcrop scale, regarding damage of construction such as a concrete retaining wall, most of the coseismic and postseismic horizontal shortening was essentially absorbed by multiple distributed brittle ruptures, which deserves attention in terms of earthquake hazard mitigation.
Comparison of measurements from satellite radiation budget instruments
Authors: Smith G. Louis , Szewczyk Z. Peter , Rutan David A. , Lee Robert B.
Published: February 2006

Successive radiometers have been flown on spacecraft for measurement of the radiation budget of the Earth and to date have provided data sets which overlap in time over a 25‐year period. Together these data sets cover two cycles of any decadal oscillation and are useful for climate research. However, before multiple data sets can be used, it is necessary first to establish precisions and relative biases of the data sets. Although these instruments were all calibrated with great care, inevitably there are differences between the instruments. Also, instruments change while in orbit due to degradation of optical elements and changes of the detectors. A number of studies have compared measurements between pairs of radiometers in order to establish these differences. In this paper we compile these results and by use of a bar chart demonstrate the traceability of calibration of satellite radiation budget instruments over these two decades. Using this compilation the differences are computed for any two instruments listed. The instruments considered here include the ERBE scanning and nonscanning radiometers, ScaRaB I and II, and the CERES instruments aboard the TRMM, Terra, and Aqua spacecraft. These results are a prerequisite to use of multiple data sets for long‐term studies of climate process. The largest biases are between the ERBS scanning and non‐scanning radiometers, which at the “top of the atmosphere” differ by 5.4 W m−2 for shortwave fluxes and by 5.8 W m−2 for daytime longwave fluxes. The standard deviations of the biases, which define how well the data sets can be connected, are less than 1 W m−2 for longwave and between 1 and 2 W m−2 for shortwave fluxes.
Binary H2SO4‐H2O homogeneous nucleation based on kinetic quasi‐unary nucleation model: Look‐up tables
Authors: Yu Fangqun
Published: February 2006

Recently, we have shown that the binary homogeneous nucleation (BHN) of H2SO4 and H2O can be treated as a quasi‐unary nucleation (QUN) of H2SO4 in the equilibrium with H2O vapor and have developed a kinetic H2SO4‐H2O nucleation model, which simulates the dynamic evolutions of cluster distributions explicitly. In this paper we present improved and updated version of the QUN model, which has been modified through the incorporation of more rigorous thermodynamics of the cluster formation and the effect of the surface area of preexisting particles on nucleation rates. The difference in the model predictions of the improved and original QUN models is not dramatic; however, the improved QUN model is more consistent thermodynamically. The predicted BHN rates based on the QUN model are in good agreement with existing observations within the range of uncertainties. We also study the dependence of kinetic BHN rates on key input parameters and discuss the conditions in which the H2SO4‐H2O homogeneous nucleation in the atmosphere may become significant. The nucleation rates look‐up tables derived from the QUN model, which can be readily used to find the nucleation rates at given conditions, are presented. The look‐up tables cover a wide range of key parameters that can be found in the ambient atmosphere, in the laboratory studies, and in the exhaust plumes. These look‐up tables can be easily incorporated in multidimensional models to predict BHN rates, and they can be utilized directly for the analysis and interpretation of the observed nucleation events.
Rocks of the Columbia Hills
Authors: Squyres Steven W. , Arvidson Raymond E. , Blaney Diana L. , Clark Benton C. , Crumpler Larry , Farrand William H. , Gorevan Stephen , Herkenhoff Kenneth E. , Hurowitz Joel , Kusack Alastair , McSween Harry Y. , Ming Douglas W. , Morris Richard V. , Ruff Steven W. , Wang Alian , Yen Albert
Published: February 2006

The Mars Exploration Rover Spirit has identified five distinct rock types in the Columbia Hills of Gusev crater. Clovis Class rock is a poorly sorted clastic rock that has undergone substantial aqueous alteration. We interpret it to be aqueously altered ejecta deposits formed by impacts into basaltic materials. Wishstone Class rock is also a poorly sorted clastic rock that has a distinctive chemical composition that is high in Ti and P and low in Cr. Wishstone Class rock may be pyroclastic or impact in origin. Peace Class rock is a sedimentary material composed of ultramafic sand grains cemented by significant quantities of Mg‐ and Ca‐sulfates. Peace Class rock may have formed when water briefly saturated the ultramafic sands and evaporated to allow precipitation of the sulfates. Watchtower Class rocks are similar chemically to Wishstone Class rocks and have undergone widely varying degrees of near‐isochemical aqueous alteration. They may also be ejecta deposits, formed by impacts into Wishstone‐rich materials and altered by small amounts of water. Backstay Class rocks are basalt/trachybasalt lavas that were emplaced in the Columbia Hills after the other rock classes were, either as impact ejecta or by localized volcanic activity. The geologic record preserved in the rocks of the Columbia Hills reveals a period very early in Martian history in which volcanic materials were widespread, impact was a dominant process, and water was commonly present.
Episodic reactivation of large‐scale push moraines in front of the advancing Taku Glacier, Alaska
Authors: Kuriger E. M. , Truffer M. , Motyka R. J. , Bucki A. K.
Published: February 2006

Taku Glacier, an advancing former tidewater glacier in Alaska, has been actively pushing its proglacial sediments along part of its terminus over the last 50 years, producing so‐called push moraines. The mobilization of these sediments, which were locally lifted more than 20 m above sea level by 2004, has happened episodically rather than steadily. The last major event of proglacial sediment deformation occurred in 2001, presumably caused by sliding along a basal detachment layer. Since then, most deformation has been localized within a few meters of the terminus, including impressive deformational features of the terminal ice, where slabs of ice, tens of centimeters in thickness, have undercut proglacial sediments and vegetation and lifted them up. Between 2002 and 2004, surface velocities and horizontal displacements were measured across the terminus and in the proglacial push moraine area. Sediment displacement was highest between the end of March and mid‐June. A decrease in displacement with distance from the terminus revealed that the sediments were deforming internally rather than along a basal décollement. We present a simple model which suggests that, under 2004 conditions, reactivation of major movement along this décollement is unlikely to happen, unless some critical factors change. These factors include (1) a steepening of the glacier surface, (2) an increased surface angle of the sediment wedge, and/or (3) higher water pressure in the system, which decreases the effective frictional resistance. An observed wet clay‐rich layer presumably acted as a major fault plane during the 2001 event.
Structure and stability of Con(pyridine)m− clusters: Absence of metal inserted structures
Authors: Douglas Edmonds B. , Kandalam A. K. , Khanna S. N. , Li X. , Grubisic A. , Khanna I. , Bowen K. H.
Published: February 2006

A synergistic approach combining the experimental photoelectron spectroscopy and theoretical electronic structure studies is used to probe the geometrical structure and the spin magnetic moment of Con(pyridine)m− clusters. It is predicted that the ground state of Co(pyridine)− is a structure where the Co atom is inserted in a CH bond. However, the insertion is marked by a barrier of 0.33eV that is not overcome under the existing experimental conditions resulting in the formation of a structure where Co occupies a site above the pyridine plane. For Co2(pyridine)−, a ground-state structure is predicted in which the Co2 diametric moiety is inserted in one of the CH bonds, but again because of a barrier, the structure which matches the photoelectron spectrum is a higher-energy isomer in which the Co2 moiety is bonded directly to nitrogen on the pyridine ring. In all cases, the Co sites have finite magnetic moments suggesting that the complexes may provide ways of making cluster-based magnetic materials.
Investigation of the disturbance of a Langmuir probe and its influence on measurement results
Authors: Brandt C. , Testrich H. , Kozakov R. , Wilke C.
Published: February 2006

Measurements of plasma parameters by Langmuir probes are influenced by the probe system itself. This article considers the deviation of plasma parameters determined by probe measurements from those in the undisturbed plasma. For this reason the particle density of the excited atoms of a neon plasma in the very vicinity of the probe is compared with the particle density in the undisturbed case. The densities of the excited metastable 1s5 level were measured by laser absorption spectroscopy. By solving the plasma balance equations the deviation of the electron density and the deviation of the electric field could be deduced.
Thin-foil magnetic force system for high-numerical-aperture microscopy
Authors: Fisher J. K. , Cribb J. , Desai K. V. , Vicci L. , Wilde B. , Keller K. , Taylor R. M. , Haase J. , Bloom K. , O’Brien E. Timothy , Superfine R.
Published: February 2006

Forces play a key role in a wide range of biological phenomena from single-protein conformational dynamics to transcription and cell division, to name a few. The majority of existing microbiological force application methods can be divided into two categories: those that can apply relatively high forces through the use of a physical connection to a probe and those that apply smaller forces with a detached probe. Existing magnetic manipulators utilizing high fields and high field gradients have been able to reduce this gap in maximum applicable force, but the size of such devices has limited their use in applications where high force and high-numerical-aperture (NA) microscopy must be combined. We have developed a magnetic manipulation system that is capable of applying forces in excess of 700pN on a 1μm paramagnetic particle and 13nN on a 4.5μm paramagnetic particle, forces over the full 4πsr, and a bandwidth in excess of 3kHz while remaining compatible with a commercially available high-NA microscope objective. Our system design separates the pole tips from the flux coils so that the magnetic-field geometry at the sample is determined by removable thin-foil pole plates, allowing easy change from experiment to experiment. In addition, we have combined the magnetic manipulator with a feedback-enhanced, high-resolution (2.4nm), high-bandwidth (10kHz), long-range (100μm xyz range) laser tracking system. We demonstrate the usefulness of this system in a study of the role of forces in higher-order chromosome structure and function.