bluuebunny/crossref_metadata_2025 huggingface dataset:
Versuche an cyklaminbehandelten Kaulquappen über die Beeinflussung der Digitoxinwirkung durch Calciumionen1
Authors: Colldahl Helge
Published: April 2012

Mit cyklaminisierten Kaulquappen (nach Overton) ist eine Serie Versuche ausgeführt worden, in der Absicht, die Bedeutung der Calciumkonzentration für die Digitoxinwirkung zu untersuchen. Diese Methode hat den Vorteil, daß sowohl die Konzentration des Calciums wie auch des Digitoxins im Blute der Froschlarven im Laufe des Versuches als konstant betrachtet werden kann.

Bei Einwirkung von Digitoxin oder erhöhtem Calciumgehalt nimmt die Pulsfrequenz der Kaulquappen sukzessiv ab, die Larven werden nach und nach stumpfer und ihre Lebensdauer wird verkürzt. Eine Digitoxinkonzentration von 1: 800000 bewirkt ungefähr die gleiche Pulsfrequenzherabsetzung wie eine Calciumkonzentration von 1: 500.

Läßt man einen erhöhten Calciumgehalt gleichzeitig mit einer gewissen Digitoxinkonzentration auf die Larven einwirken, so wird regelmäßig die Lebensdauer der Larven nicht so stark eingeschränkt, wie unter Einwirkung der gleichen Digitoxinkonzentration beim Calciumgehalt der Normalringerlösung. Bei gesenktem Calciumgehalt verkürzt dieselbe Digitoxinkonzentration die Lebensdauer in den meisten Fällen mehr als beim Calciumgehalt der Normalringerlösung. Weiter halten sich die Larven bedeutend länger lebhaft unter der Einwirkung einer gewissen Digitoxinkonzentration, wenn der Calciumgehalt der Ringerlösung gleichzeitig erhöht ist. Senkt man andrerseits den Calciumgehalt in der Ringerlösung, so stumpfen sie rascher ab unter der Einwirkung der gleichen Digitoxinkonzentration.

Ein Antagonismus zwischen Calcium und Digitoxin scheint also in unseren Versuchen vorzuliegen, bei dem Calcium die toxische Wirkung des Digitoxins abdämpft. Er scheint zu bestehen obwohl die Larven sowohl auf Digitoxinzusatz wie auf Erhöhung der Calciumkonzentration scheinbar auf dieselbe Weise reagieren. Es ist wahrscheinlich, daß dieser Antagonismus teilweise auf die membranabdichtende Wirkung des Calciums und somit auf ein erschwertes Eindringen des Digitoxins zurückzuführen ist. Ob Digitoxin und Calcium auch auf andere Art antagonistisch gegeneinander wirken, ist nicht zu entscheiden, gewisse Tatsachen deuten jedoch darauf hin.

Unsere Ergebnisse sprechen recht wesentlich gegen die meisten, auf tierexperimentelle Untersuchungen begründeten Auffassungen über die Beziehungen zwischen Calcium‐und Digitoxinwirkung, was vielleicht zum Teil durch die relativ ausgedehnte Versuchsdauer bei der hier angewandten Methodik zu erklären ist. Dagegen stimmen unsere Ergebnisse ziemlich gut mit gewissen klinischen Erfahrungen überein, die deshalb in Kürze erwähnt werden.
Calciumbestimmung im Harn und in den Faeces nach Hans Aron, besonders mit Rücksicht auf Stoffwechselversuche an Ratten1
Authors: Von Hammarsten Greta
Published: April 2012

Arons Calcium‐Bestimmungsmethode ist nachgeprüft worden, besonders für die Bestimmung von Calcium im Harn und in den Faeces bei Stoffwechselversuchen an Ratten. Calcium wird mit Alkohol in stark schwefelsaurer Lösung als CaSO4, 2 H2O gefällt. In der Lösung dürfen nur Spuren von SiO2 zu finden sein.

Beim Ausführen der Analyse müssen die angegebenen Proportionen zwischen Schwefelsäure, Wasser und Fällungsalkohol eingehalten werden.

Die vorliegende Untersuchung wurde mit Unterstützung der Stiftung »Therese och Johan Anderssons Minne« ausgeführt.
Zur Kenntnis der wasserstoffaktivierenden Fähigkeit der Brauerei‐und der Preßhefe in phosphatfreiem und phosphathaltigem Medium mit und ohne Zusatz gewisser organischer Säuren und gewisser Zuckerarten1
Authors: Von Thunberg Torsten
Published: April 2012

Die von Wieland und Claren mitgeteilte und auch von Sonderhoff untersuchte Beobachtung, daß Hefe bei anaeroben Mb.‐Versuchen Acetat und Succinat nicht als Wasserstoffdonatoren benutzen kann, trotzdem diese Stoffe bei aeroben Versuchen die Sauerstoffaufnahme der Hefe steigern, ist vom Verf. weiter verfolgt worden. Hierbei zeigt es sich, daß die Gültigkeit des von den genannten Forschern gefundenen Verhältnisses daran gebunden ist, daß der Versuch in einem Milieu mit ausreichend starkem Phosphatgehalt ausgeführt wird. Untersucht man dagegen gewaschene Hefe, die in Wasser aufgeschwemmt ist, so zeigt sie sich imstande, sowohl Acetat als Succinat als Wasserstoffdonator zu benutzen. Dies gilt sowohl für Preßhefe als für Brauereihefe. — In Wasser aufgeschwemmte Hefe besitzt eine deutliche Fähigkeit, auch Ameisensäure, Essigsäure, Milchsäure, 1‐Apfelsäure und Glycerinphosphorsäure als Donatorsubstanzen zu gebrauchen. Diese Substanzen treten als Donatorsubstanzen mehr oder weniger deutlich auch in phosphathaltigem Milieu auf, besonders wenn der Phosphatgehalt nicht zu stark ist. — Ein Zusatz von Glykose, Laevulose, Mannose oder Saccharose zu in Wasser aufgeschwemmter Preßhefe übt eine deutlich hemmende Wirkung auf die Mb.‐Entfärbung derselben aus. Dieselben Zuckerarten stimulieren dagegen stark die Fähigkeit der Brauereihefe, in phosphatfreiem Medium Methylenblau zu entfärben. Führt man analoge Versuche in Phosphatmilieu aus, so stimuliert ein Zusatz der genannten Zuckerarten die Entfärbungsfähigkeit nicht nur der Brauereihefe, sondern auch der Preßhefe. Maltose, Lactose und Trehalose erweisen sich bei den hier in Frage stehenden Versuchen als völlig indifferent.

Johan och Therese Anderssons Minnesfond sage ich für die Bereitstellung von Mitteln für die Durchführung dieser Untersuchungen meinen Dank.
Die hemmende Wirkung der Erdalkalien und besonders des Kalkes auf gewisse physiologische Oxydationsprozesse1
Authors: Thunberg T.
Published: April 2012

Verf. beschreibt die kräftige hemmende Wirkung, die CaCl2 und SrCl2 auf die enzymatische Aktivität eines dehydrogenasehaltigen Phosphatextraktes aus Pisum sativum und gewissen anderen Samenarten ausüben. Auch BaCl2 übt eine gewisse, wenn auch schwächere hemmende Wirkung aus. Diese Hemmungswirkung dieser Erdalkalien läßt sich nicht als eine reine Salzwirkung erklären. Kontrollversuche mit den Chloriden Na, K und NH4 zeigen, daß die hemmende Wirkung derselben erst bei wesentlich höherer Konzentration hervortritt. — Die Hemmungswirkung der Erdalkalien setzt Verf. mit ihrer ansäuernden Wirkung in Zusammenhang. Bringt man neutral reagierende Erdalkalichloride mit neutral oder schwach basisch reagierendem Alkaliphosphat zusammen, so fallen basische Erdalkaliphosphate aus, wobei die über der Fällung stehende Flüssigkeit sauer reagiert. Quantitative Versuche zeigen, daß eine praktisch totale Hemmung der Entfärbungsfähigkeit des enzymatischen Systems gegenüber einem Redox‐Indikator bei demselben pH eintritt, einerlei ob der pH‐Wert durch Phosphatpufferung oder durch Zusatz eines Erdalkalichlorids zu dem phosphathaltigen Enzymextrakt erhalten wird. Da gewisse Dehydrogenasesysteme nur in Gegenwart von Phosphat wirken, dürfte die hemmende Wirkung der Alkalichloride auch darauf beruhen, daß sie den eben genannten Dehydrogenasen das für ihre Wirkung notwendige Phosphat entziehen. — Verf. hebt hervor, daß sich seine Erklärung nur auf die von ihm untersuchten Dehydrogenisierungsprozesse bezieht.

Der Stiftung Therese och Johan Anderssons Minne danke ich für finanzielle Unterstützung der vorliegenden Untersuchung.
Ein Reizapparat zu physiologischen Zwecken1
Authors: Wilska Alvar
Published: April 2012

Es werden die Vorteile und die Funktionsweise eines neuen Reizgeräts beschrieben. Durch seine vielseitige Anwendbarkeit (die Vorteile des Apparats sind am Anfang dieser Abhandlung in einigen Punkten zusammengefaßt) und Stabilität ist dieser Apparat zu verschiedenen Zwecken der Elektrophysiologie, besonders im Zusammenhang mit der sog. Querkippmethode, sehr geeignet.
Untersuchungen über die Geschwindigkeit des geleiteten Aktionspotentials einer Muskelfaser bei verschiedenen Dehnungszuständen des Muskels1
Authors: Wilska Alvar , Varjoranta K.
Published: April 2012

Wird der Muskel in seiner Längsrichtung gedehnt, so verlängert sich die Zeit, die das Aktionspotential braucht, um von dem einen Ende der Muskelfaser zum anderen zu gelangen. Die Vergrößerung der Leitungszeit ist jedoch relativ kleiner als die Verlängerung der Muskelfaser, so daß sich die Leitungsgeschwindigkeit bei zunehmender Dehnung des Muskels vergrößert. Einer 50% Dehnung der Muskelfaser entspricht eine Zunahme von etwa 10% der Leitungsgeschwindigkeit des Aktionspotentials.
Über den Winterschlaf des Igels Der Carotin‐ und Vitamin‐A‐Stoffwechsel1
Authors: Suomalainen Paavo
Published: April 2012

Verfasser hat den Carotin‐ und Vitamin‐A‐Gehalt der Leber sowie des Serums vom Igel im Frühjahr recht bald nach dem Aufwachen der Tiere aus dem Winterschlaf, im Spätsommer, als die Tiere noch sommerlich rege waren, im Spätherbst zur Zeit des eben beginnenden Winterschlafes, im Hochwinter, als die Tiere im tiefsten Winterschlaf versunken waren, ebenso wie im Vorfrühling gerade beim Erwachen der Tiere aus dem Winterschlaf untersucht.

Die Carotinbestimmungen erfolgten kolorimetrisch und die Bestimmung des Vitamins A vermittels der Carr‐Price‐Reaktion mit dem Pulfrich‐Stufenphotometer von Zeiss. Die Methode der Bestimmung wird oben eingehend beschrieben.

Der Vitamin‐A‐Gehalt der Leber verminderte sich langsam im Laufe des Winterschlafes und diese Verminderung dauerte trotz der Fütterung der Tiere auch in den Sommer hinein fort, so daß der Vitamin‐A‐Gehalt der Leber im Spätsommer sein Minimum erreichte. Vor dem Eintritt des Winterschlafes fand eine starke Anreicherung von Vitamin A in der Leber statt. Der Vitamin‐A‐Gehalt des Serums erreichte sein Minimum beim Beginn des Winterschlafes und sein Maximum beim Erwachen der Tiere aus demselben.

Der Carotingehalt des Serums war im Sommer, als die Tiere Nahrung erhielten, höher als während der Winterschlafperiode.

Das Verhältnis Vitamin A/Carotin war sowohl in der Leber als im Serum im Winter viel größer als im Sommer.

Die Veränderungen im Vitamin‐A‐Gehalt leiten sich wahrscheinlich wenigstens zum Teil auf die periodischen Schwankungen in der Tätigkeit der endokrinen Drüsen zurück.
Über die Art des Reflexmechanismus, der einen chemischen Reiz von der Haut auf die peripheren Gefäße der inneren Organe überträgt1
Authors: Andersson N. , Ekström T.
Published: April 2012

. Die Leitungsbahnen des von G. von Reis und F. Sjöstrand nachgewiesenen kutoviszeralen Reflexes, der unter anderem durch chemische Hautreize ausgelöst wird und eine Zunahme der peripheren Blutmenge der inneren Organe bewirkt, wurden studiert.

. Daß es sich dabei um eine nervös bedingte Übertragung des Reizes handelt, konnte als auch für Kaninchen gültig bestätigt werden.

. Bei Kaninchen verläuft der Reflex extraspinal.

. Bei Meerschweinchen scheint er teilweise segmental zu sein.

. Dennoch erhielt man eine deutliche Wirkung auch bei Reizung kleiner Bezirke, und zwar im großen Ganzen unabhängig von ihrer Lage. Die Wirkung wechselte ihrer Stärke nach bei wechselnder Lage des gereizten Bezirks.
Photoelektrische Methode zur Bestimmung der Permeierungsgeschwindigkeit von Anelektrolyten durch die Membran von roten Blutkörperchen
Authors: Meldahl K. F. , Ørskov Sören L.
Published: April 2012

Die Apparatur und deren Anwendung für eine Mikromethode zur Bestimmung der Permeabilität der roten Blutkörperchen wird beschrieben. Die Grundlage der Methode beruht, ebenso wie die früher von Ørskov beschriebene, auf der Beobachtung, daß die Lichtdurchlässigkeit einer Blutkörperchensuspension von der Größe der Blutkörperchen abhängt.

Die Permeierungsgeschwindigkeit wird nach dem Fickschen Gesetz berechnet. Es zeigte sich aber, daß die Ergebnisse für die untersuchten vier Stoffe, Glyzerin, Thioharnstoff, Malonamid und Glukose sehr schlecht mit dem Fickschen Gesetz übereinstimmen. Es wird daher empfohlen, mehrere Punkte im Verlauf der Permeierung zu definieren und gleichzeitig die gefundenen Versuchszeiten anzugeben.

Die Versuche deuten darauf hin, daß die Poren der Blutkörperchenmembran verkleinert werden, wenn die Blutkörperchen schrumpfen. Dementsprechend findet sich in 0,9% NaCl‐Lösung eine langsamere Permeierung als in 0,7%.

Es wird erörtert, welche Faktoren für den Verlauf der Permeierung Bedeutung haben u. a. das verschiedene Alter der Blutkörperchen in ein und derselben Probe.

Zugabe von Natriumzitrat und auch von NaCl verringern die Lichtdurchlässigkeit einer Blutkörperchensuspension mehr als die Zufuhr von Glukose und Mannit auch dann, wenn die Gefrierpunktserniedrigung in gleichem Maße erhöht ist. Es wird angenommen, daß Zitrat die Lichtdurchlässigkeit der Membran verändert. Dies ist für Glyzerin, Thioharnstoff und Glukose nicht der Fall.

Stehen der Suspension verringert in einigen Fällen die Permeierungsgeschwindigkeit; dies trifft besonders für Glukose beim menschlichen Blut zu.
Efficacy of patient questionnaire in predicting renal dysfunction in outpatients older than 60 years of age prior to contrast‐enhanced computed tomography
Authors: Lui Elaine H , Lau Kenneth K , Polkinghorne Kevan , Chang Chian A , Ardley Nicholas
Published: April 2012

Introduction: Contrast‐induced nephropathy (CIN), a common iatrogenic cause of acute renal failure, is preventable. Identification of impaired renal function prior to intravenous contrast is important. Questionnaire screening has been useful to negate the need for cumbersome and costly renal function testing on all patients prior to contrast‐enhanced CT (CECT). The Royal Australian and New Zealand College of Radiologists guidelines include age older than 60 as a risk marker requiring renal function testing. The aim of this retrospective study is to assess the efficacy of the pre‐CT questionnaire in identifying patients with pre‐existing renal impairment even in this older than 60 age group.

Methods: All outpatients were given questionnaires containing 11 CIN risk markers prior to CECT. Radiographers documented age, gender, serum creatinine and/or estimated glomerulofiltration rate (eGFR mL/min/1.72 m2) within 3 months of CT. Questionnaires of all patients older than 60 years were collated. The data was tabulated and analyzed. Incomplete questionnaires were excluded.

Results: 134/171 (78.4%) patients had eGFR ≥ 60 and 37/171 (21.6%) had eGFR < 60, with 31/171 (18.1%) having eGFR between 30 and 60 and 3/171 (1.8%) having eGFR < 30. 47/171 (27.5%) circled ‘no’ to all risk markers. Percentage for sensitivity is 81.1% (95% confidence interval (CI) 64.8–92%), for specificity 29.9% (95% CI 22.3–38.4%), for positive predictive value 24.2% (95% CI 17–32.7%) and for negative predictive value 85.1% (95%CI 71.7–93.8%). Kidney disease, anaemia, myeloma and vasculitis seem to be statistically significant risk factors (P < 0.05). All three true‐positive patients with eGFR < 30 indicated known kidney disease. Seven false‐negative patients had eGFR 30–60, with 4/7 (57.1%) having CIN risk markers in their medical records.

Conclusion: Questionnaire screening for CIN risk has a high negative predictive value (85.1%) even in patients older than 60 years.
Common patterns in 558 diagnostic radiology errors
Authors: Donald Jennifer J , Barnard Stuart A
Published: April 2012

Introduction: As a Quality Improvement initiative our department has held regular discrepancy meetings since 2003. We performed a retrospective analysis of the cases presented and identified the most common pattern of error.

Methods: A total of 558 cases were referred for discussion over 92 months, and errors were classified as perceptual or interpretative. The most common patterns of error for each imaging modality were analysed, and the misses were scored by consensus as subtle or non‐subtle.

Results: Of 558 diagnostic errors, 447 (80%) were perceptual and 111 (20%) were interpretative errors. Plain radiography and computed tomography (CT) scans were the most frequent imaging modalities accounting for 246 (44%) and 241 (43%) of the total number of errors, respectively. In the plain radiography group 120 (49%) of the errors occurred in chest X‐ray reports with perceptual miss of a lung nodule occurring in 40% of this subgroup. In the axial and appendicular skeleton missed fractures occurred most frequently, and metastatic bone disease was overlooked in 12 of 50 plain X‐rays of the pelvis or spine. The majority of errors within the CT group were in reports of body scans with the commonest perceptual errors identified including 16 missed significant bone lesions, 14 cases of thromboembolic disease and 14 gastrointestinal tumours. Of the 558 errors, 312 (56%) were considered subtle and 246 (44%) non‐subtle.

Conclusion: Diagnostic errors are not uncommon and are most frequently perceptual in nature. Identification of the most common patterns of error has the potential to improve the quality of reporting by improving the search behaviour of radiologists.
Medulloblastoma: Progress over time
Authors: Smee Robert I , Williams Janet R , De‐loyde Katie J , Meagher Nicola S , Cohn Richard
Published: April 2012

Introduction: Medulloblastoma is the most common central nervous system tumour in children aged 0–4 years, with 75% of cases occurring in patients <16 years, and rare in adults. The intent of this audit is to review a single centre's experience and to compare outcomes with other centres' outcomes.

Methods: This Ethics approved retrospective audit evaluates the paediatric population aged <16 years who received radiotherapy as their initial or salvage treatment at the Prince of Wales Hospital Cancer Centre between 1972 and 2007. The primary and secondary end‐points were progression‐free survival (PFS) and cancer‐specific survival (CSS), with comparisons made between patients treated before and after 1990, and the impact of high‐ and low‐risk disease.

Results: There were 80 eligible patients, 78 who had radiotherapy at initial presentation, and 2 at the time of recurrence. Median age was 6.5 years, 52 were boys and 28 were girls. Seventy‐eight patients had a surgical procedure and ultimately received craniospinal radiotherapy. Of these 78 patients, 32 (40%) had a macroscopically complete resection. The 5‐year PFS was 69.7%. The 5‐year PFS for patients treated pre and post 1990 was 66.1% and 71.8%, respectively. The 5‐year CSS for high‐ and low‐risk patients was 61.1% and 78.4%, respectively. Ultimately, 33% of patients were dead due to disease.

Conclusion: This audit demonstrates those children referred to this facility for treatment have comparable survival to that of other major centres.
Impact of FDG‐PET on lung cancer delineation for radiotherapy
Authors: Morarji Kavita , Fowler Allan , Vinod Shalini K , Ho Shon Ivan , Laurence Jerome M
Published: April 2012

Purpose: The purpose of this study is to assess the impact of fused diagnostic F‐18 2‐fluoro‐2‐deoxy‐D‐glucose (FDG) positron emission tomography (PET)/computed tomography (CT) and planning FDG‐PET/CT scans on voluming of lung cancer for radiotherapy.

Methods: Five radiation oncologists (ROs), five radiation oncology trainees and a radiologist contoured five cases of non‐small cell lung cancer. The CT alone, the diagnostic FDG‐PET/CT and planning FDG‐PET/CT each registered to the CT, were used to contour three volumes. The concordance index (CI) was used to compare each volume with a reference RO.

Results: Although there was considerable inter‐observer variability in CT contouring, there was no significant difference between mean volumes of the gross tumour volume for the RO and radiation oncology trainees using any technique. There was no increase in CI with the addition of PET/CT, either diagnostic or planning, for the RO. However, the volumes of the radiation oncology trainees showed a significant increase in CI from 65.8% with CT alone to 68.0% and 72.3% with diagnostic PET/CT and planning PET/CT, respectively (P = 0.028). Mean variation at the tumour/mediastinum interface was significantly reduced with addition of registered PET/CT.

Conclusions: The concordance of RO with the reference RO did not significantly increase with use of integrated FDG PET/CT images. However, the contouring of radiation oncology trainees' became more concordant with the reference.
Russia and America in the Asia‐Pacific: A New Entente?
Authors: Lukin Artyom
Published: April 2012

Historically, Russia‐U.S. political interaction in the Pacific has mostly been defined by the balance of power logic. Moscow and Washington only cooperated when they faced a common threat. In the 1860s it was the British Empire that was seen as such a threat, whereas from the 1920s through the 1940s it was Japan. Today another geopolitical entente of Russia and America might be in the offing, motivated by the rise of China. Such options are already being discussed by Russian experts and are perhaps also being contemplated by strategic planners in Washington. If Russia and the United States are to establish an effective partnership in the Asia‐Pacific, they will need to resolve, or at least moderate, their disagreements in other areas, especially in the post‐Soviet space. Furthermore, they have to do something about the lack of substantial economic ties as well as bridge the gap in their political identities.
China's Strategy for Energy Acquisition in the Middle East: Potential for Conflict and Cooperation With the United States
Authors: Dorraj Manochehr , English James E.
Published: April 2012

In this article, the authors examine China's evolving energy strategy in the Middle East, particularly in the three countries that have the largest energy reserves and form the epicenter of the U.S.‐China rivalry: Saudi Arabia, Iran, and Iraq. With $3 trillion in foreign currency reserves, Beijing is increasingly using its cash to secure future long‐term access to energy in the region. Through energy‐backed loans, as well as upstream and downstream joint ventures, China's policy banks and its national oil companies are pumping up the volume of oil and gas that will flow from the Middle East to the mainland in the 21st century. At the same time, Beijing is embedding itself deeply in the economies of these major oil‐producing states through expanded bilateral trade involving multiple sectors of the Chinese economy. Beijing's monetary strength, coupled with its lack of military involvement and political baggage in the region, has China poised to benefit from its expansive access to the region's energy resources. This article critically examines the political implications of China's energy acquisition strategy, the potential for conflict as well as cooperation with the United States, and the possibility of the realignment of great powers in the Middle East.
Red‐Shirt Heartland: Village‐Level Socioeconomic Change in Northeast Thailand Between 1999 and 2008
Authors: de Jong Edwin , Knippenberg Luuk , Ayuwat Dusadee , Promphakping Buapun
Published: April 2012

In this article, we investigate the socioeconomic changes that took place on a village level in northeast Thailand during Thaksin Shinawatra's rule as prime minister of Thailand (2001–2006). By comparing data from 1999 and 2008, we show that most households in the research villages have become wealthier. The analysis reveals that household characteristics are not significant in explaining the increase in wealth but that the triggers for change have to be sought on a higher level. This does not necessarily mean that development was the result of measures taken by the Thai government during or before the Thaksin regime, the quick recovery of the Asian economy after 2001, or a combination of both. It, however, leads to an understanding of why so many people in northeast Thailand are still supporting Thaksin or a Thaksinite party up until today.
Low sleep and low socioeconomic status predict high body mass index: a 4‐year longitudinal study of Australian schoolchildren
Authors: O'Dea J. A. , Dibley M. J. , Rankin N. M.
Published: April 2012

Objective

The objective of this study was to examine the longitudinal relationships between body mass index (BMI), sleep duration and socioeconomic status (SES) in a 4‐year cohort of 939 children aged 7–12 years.

Methods

Children and their mothers completed an annual questionnaire to assess usual weekday sleep and wake times, amount of sleep, physical activity, parental education and school SES. 93% of children were enrolled (939/1010) and retention was 88%, 83% and 81% in consecutive years. Height and weight were measured annually.

Results

BMI increased with decreasing amount of sleep and less sleep predicted greater International Obesity Task Force measures of obesity and overweight. In all 4 years, after controlling for baseline BMI, low SES was a significant predictor of high BMI. Children in the upper tertile of sleep in year 1 had a 2.3 kg lower weight gain (standard error [SE]: 0.5) between years 1 and 4 (P < 0.0001) than children in the lower tertile of sleep and a 0.45 kg m−2 lower increase in BMI (SE: 0.15) (P = 0.004). The difference between children with consistently low and high sleep duration over 4 years was 1 BMI point. Those with the lowest BMI were the children with both high SES and high sleep duration. PA was not associated with BMI.

Conclusions

Both low SES and short sleep duration predict obesity risk in children after controlling for baseline BMI and this trend becomes stronger as children enter adolescence. Obesity prevention should include a sleep promotion component and this may be more beneficial to children of low SES and/or socially disadvantaged backgrounds.
Non-Fourier Heat Conduction in Carbon Nanotubes
Authors: Wang Hai-Dong , Cao Bing-Yang , Guo Zeng-Yuan
Published: April 2012

Fourier’s law is a phenomenological law to describe the heat transfer process. Although it has been widely used in a variety of engineering application areas, it is still questionable to reveal the physical essence of heat transfer. In order to describe the heat transfer phenomena universally, Guo has developed a general heat conduction law based on the concept of thermomass, which is defined as the equivalent mass of phonon gas in dielectrics according to Einstein’s mass–energy relation. The general law degenerates into Fourier’s law when the thermal inertia is neglected as the heat flux is not very high. The heat flux in carbon nanotubes (CNTs) may be as high as 1012 W/m2. In this case, Fourier’s law no longer holds. However, what is estimated through the ratio of the heat flux to the temperature gradient by molecular dynamics (MD) simulations or experiments is only the apparent thermal conductivity (ATC); which is smaller than the intrinsic thermal conductivity (ITC). The existing experimental data of single-walled CNTs under the high-bias current flows are applied to study the non-Fourier heat conduction under the ultrahigh heat flux conditions. The results show that ITC and ATC are almost equal under the low heat flux conditions when the thermal inertia is negligible, while the difference between ITC and ATC becomes more notable as the heat flux increases or the temperature drops.
An Accurate and Stable Numerical Method for Solving a Micro Heat Transfer Model in a One-Dimensional N-Carrier System in Spherical Coordinates
Authors: Dai Weizhong , Tzou Da Yu
Published: April 2012

We consider the generalized micro heat transfer model in a 1D microsphere with N-carriers and Neumann boundary condition in spherical coordinates, which can be applied to describe nonequilibrium heating in biological cells. An accurate Crank–Nicholson type of scheme is presented for solving the generalized model, where a new second-order accurate numerical scheme for the Neumann boundary condition is developed so that the overall truncation error is second order. The scheme is proved to be unconditionally stable and convergent. The present scheme is then tested by three numerical examples. Results show that the numerical solution is much more accurate than that obtained based on the Crank–Nicholson scheme with the conventional method for the Neumann boundary condition. Furthermore, the convergence rate of the present scheme is about 1.8 with respect to the spatial variable, while the convergence rate of the Crank–Nicholson scheme with the conventional method for the Neumann boundary condition is only 1.0 with respect to the spatial variable. The scheme is ready to apply for thermal analysis in N-carrier systems.
Characterization of Surface Roughness Effects on Laminar Flow in Microchannels by Using Fractal Cantor Structures
Authors: Chen Yongping , Zhang Chengbin , Fu Panpan , Shi Mingheng
Published: April 2012

The fractal characterization of surface topography by using Cantor set structures is introduced to quantify the microchannel surface. Based on this fractal characterization of surface, a model of laminar flow in rough microchannels is developed and numerically analyzed in this paper. The effects of Reynolds number, relative roughness, and fractal dimension on laminar flow are all discussed. The results indicate that the presence of roughness leads to the form of detachment, and the eddy generation is observed at the shadow of the roughness elements. The pressure drop in the rough microchannels along the flow direction is larger than that in the smooth channel. It is no longer in a linear fashion and the fluctuation in pressure drop along the stream due to the vortex near the wall is found. Differing from the smooth channel, the Poiseuille number for laminar flow in rough microchannels is no longer only dependent on the cross-sectional shape of the channel, but also strongly influenced by the Reynolds number, roughness height, and fractal dimension (spectrum) of the surface.
Fabrication and Experimental Characterization of Nanochannels
Authors: Phan Vinh-Nguyen , Nguyen Nam-Trung , Yang Chun , Joseph Pierre , Gué Anne-Marie
Published: April 2012

Nanofluidics is the science and technology involving a fluid flowing in or around structures with a least one dimension in the nanoscale, which is defined as the range from 1 nm to 100 nm. In this paper, we present the fabrication and characterization of nanochannels in silicon and glass. Since the lateral dimension of the channels is limited by the wavelength of UV light used in photolithography, the channel width can only be fabricated in the micrometer scale. However, the depth of the channel can be controlled precisely by the etching rate of reactive ion etching (RIE). Microchannels and access holes were etched with deep reactive ion etching (DRIE). Both nanochannels and microchannels were sealed by a Pyrex glass wafer using anodic bonding. The fabricated nanochannels were characterized by capillary filling and evaporation experiments. Due to the small channel height and weak fluorescent signal, fluorescent techniques are not suitable for the characterization of the nanochannels. A long exposure time is needed because of the limited amount of fluorescent molecules inhibit the measurement of transient and dynamic processes. However, as the channel height is shorter than all visible wavelengths, the contrast in refractive indices of air and liquid allows clear visualization of nanochannels filled with liquids. Automatic image processing with matlab allows the evaluation of capillary filling in nanochannels. Interesting phenomena and discrepancies with conventional theories were observed.
Feedstock Diffusion and Decomposition in Aligned Carbon Nanotube Arrays
Authors: Xiang Rong , Einarsson Erik , Shiomi Junichiro , Maruyama Shigeo
Published: April 2012

Feedstock diffusion and decomposition in the root growth of aligned carbon nanotube (CNT) arrays is discussed. A nondimensional modulus is proposed to differentiate catalyst poisoning controlled growth deceleration from one which is diffusion controlled. It is found that, at present, aligned multiwalled carbon nanotube (MWNT) arrays are usually free of feedstock diffusion resistance. However, for single-walled carbon nanotube (SWNT) arrays, since the intertube distance is much smaller than the mean free path of carbon source (ethanol here), high diffusion resistance in some currently available samples is significantly limiting the growth rate. The method presented here is also able to predict the critical lengths in different chemical vapor deposition (CVD) processes from which CNT arrays begin to meet this diffusion limit, as well as the possible solutions to this diffusion caused growth deceleration. The diffusion of carbon source inside of an array becomes more important when we found ethanol undergoes severe thermal decomposition at the reaction temperature. This means, in a typical alcohol CVD, hydrocarbons and radicals decomposed from ethanol may collide and react with the outer walls of SWNTs before reaching catalyst particles. When flow rate is low and ethanol is thoroughly decomposed, the produced SWNTs contain more soot structures than the SWNTs obtained at higher ethanol flow rate. Understanding the mass transport and reaction inside a SWNT array is helpful to synthesize longer and cleaner SWNTs.
Theoretical Two-Dimensional Modeling of Gas Conduction Between Finite Parallel Plates in High Vacuum
Authors: Zhu Taishan , Ye Wenjing
Published: April 2012

A theoretical approach based on gaskinetic theory is described and applied for the modeling of steady-state free-molecule gaseous heat conduction within a diffusive enclosure. With a representative model of microelectromechanical system (MEMS) devices with integrated heaters, the heat transfer between the heated component and its gaseous ambient enclosed in a high vacuum is studied in detail. A molecular simulation based on the direct simulation Monte Carlo (DSMC) method is also employed to validate the theoretical solutions and to study the effects of incomplete thermal accommodation. The impacts of the finite size of the heated beam as well as the gap between the beam and a substrate on the heat transfer are investigated to examine the appropriateness of the common assumptions employed in the modeling of Pirani sensors. Interesting phenomena that are unique in the free-molecule regime are observed and discussed. These studies are valuable to the design of MEMS devices with microheaters.
Microfluidic Bubble Generation by Acoustic Field for Mixing Enhancement
Authors: Wang Shasha , Huang Xiaoyang , Yang Chun
Published: April 2012

We demonstrate the bubble generation in a microfluidic channel by both experimental observation and numerical simulations. The microfluidic channel contains a nozzle-shaped actuation chamber with an acoustic resonator profile. The actuation is generated by a piezoelectric disk below the chamber. It was observed that for a steady deionized (DI) water flow driven through the channel, bubbles occurred in the channel when the piezoelectric disk was actuated at frequencies between 1 kHz and 5 kHz. Outside this actuation frequency range, no bubble generation was observed in the channel. The experiment showed that the presence of bubbles in this frequency range could significantly enhance the fluid mixing in the microfluidic channel, which otherwise would not happen at all without the bubbles. To further understand the bubble generation, the flow field in the microchannel was numerically simulated by a two-dimensional model. The numerical results show that there is a low pressure region inside the actuation chamber where water pressure is below the corresponding vapor pressure and thus bubbles can be generated. The bubble generation was also experimentally observed in the microchannel by using a high speed camera.
Effects of Surface Topography and Colloid Particles on the Evaporation Kinetics of Sessile Droplets on Superhydrophobic Surfaces
Authors: Xu Wei , Choi Chang-Hwan
Published: April 2012

In this paper, the evaporation kinetics of microliter-sized sessile droplets of gold colloids (∼250 nm in particle diameters) was experimentally studied on micropatterned superhydrophobic surfaces, compared with those of pure water on a planar hydrophobic surface. The structural microtopography of superhydrophobic surfaces was designed to have a constant air fraction (∼0.8) but varying array patterns including pillars, lines, and wells. During evaporation in a room condition, the superhydrophobic surfaces exhibited a stronger pinning effect than a planar surface, especially in the initial evaporation stage, with significant variations by the surface topographies. Compared to a pure water droplet, colloids exhibited further promoted pinning effects, mainly in the later stage of evaporation. While the well-known evaporative mass transport law of sessile droplets (i.e., linear law of “V2/3∝t”) was generally applicable to the superhydrophobic surfaces, much smaller evaporation rate constants were measured on the patterned superhydrophobic surfaces than on a planar hydrophobic surface. A colloidal droplet further showed lower evaporation rate constants than a pure water droplet as the concentration of particles in the droplets increased over the evaporation. Such transition was more dramatic on a planar surface than on the micropatterned surfaces. Whereas there was no clear correlation between evaporation mode and the evaporation rate observed on the superhydrophobic surfaces, the prominent decrease of the evaporation rate on the planar hydrophobic surface was accompanied with the onset of a second pinning mode.
Rolling Bearing Stress Based Life—Part I: Calculation Model
Authors: Houpert L. , Chevalier F.
Published: April 2012

Rolling contact bearing life is calculated using stresses calculated at the surface and in the volume. Surface stresses account for profile and misalignment as well as asperity deformations. Sub-surface stresses are calculated beneath the asperities (for defining the life of the surface) and deeper in the volume for calculating the life of the volume. The stress-life criterion adopted is the Dang Van one in which the local stabilized shear stress is compared to the material endurance limit defined as a function of the hydrostatic pressure (itself a function of the contact pressure) but also residual stresses and hoop stresses (due to fit). A stress-life exponent c, of the order of 4 (instead of 34/3 in the standard Lundberg and Palmgren model) is used for respecting a local load-life exponent of 10/3 at typical load levels. Life of any circumferential slices of the inner, outer, and roller is defined for obtaining the final bearing life. Trends showing how the bearing life varies as a function of the applied bearing load and Λ ratio (film thickness/RMS roughness height) are given.
Water‐equivalent path length calibration of a prototype proton CT scanner
Authors: Hurley R. F. , Schulte R. W. , Bashkirov V. A. , Wroe A. J. , Ghebremedhin A. , Sadrozinski H. F.‐W. , Rykalin V. , Coutrakon G. , Koss P. , Patyal B.
Published: April 2012

Purpose:

The authors present a calibration method for a prototype proton computed tomography (pCT) scanner. The accuracy of these measurements depends upon careful calibration of the energy detector used to measure the residual energy of the protons that passed through the object.

Methods:

A prototype pCT scanner with a cesium iodide (CsI(Tl)) crystal calorimeter was calibrated by measuring the calorimeter response for protons of 200 and 100 MeV initial energies undergoing degradation in polystyrene plates of known thickness and relative stopping power (RSP) with respect to water. Calibration curves for the two proton energies were obtained by fitting a second‐degree polynomial to the water‐equivalent path length versus calorimeter response data. Using the 100 MeV calibration curve, the RSP values for a variety of tissue‐equivalent materials were measured and compared to values obtained from a standard depth‐dose range shift measurement using a water‐tank. A cylindrical water phantom was scanned with 200 MeV protons and its RSP distribution was reconstructed using the 200 MeV calibration.

Results:

It is shown that this calibration method produces measured RSP values of various tissue‐equivalent materials that agree to within 0.5% of values obtained using an established water‐tank method. The mean RSP value of the water phantom reconstruction was found to be 0.995 ± 0.006.

Conclusions:

The method presented provides a simple and reliable procedure for calibration of a pCT scanner.
Calculation of conversion factors for effective dose for various interventional radiology procedures
Authors: Compagnone Gaetano , Giampalma Emanuela , Domenichelli Sara , Renzulli Matteo , Golfieri Rita
Published: April 2012

Purpose:

To provide dose‐area‐product (DAP) to effective dose (E) conversion factors for complete interventional procedures, based on in‐the‐field clinical measurements of DAP values and using tabulated E/DAP conversion factors for single projections available from the literature.

Methods:

Nine types of interventional procedures were performed on 84 patients with two angiographic systems. Different calibration curves (with and without patient table attenuation) were calculated for each DAP meter. Clinical and dosimetric parameters were recorded in‐the‐field for each projection and for all patients, and a conversion factor linking DAP and effective doses was derived for each complete procedure making use of published, Monte Carlo calculated conversion factors for single static projections.

Results:

Fluoroscopy time and DAP values for the lowest‐dose procedure (biliary drainage) were approximately 3‐fold and 13‐fold lower, respectively, than those for the highest‐dose examination (transjugular intrahepatic portosystemic shunt, TIPS). Median E/DAP conversion factors from 0.12 (abdominal percutaneous transluminal angioplasty) to 0.25 (Nephrostomy) mSvGy−1 cm−2 were obtained and good correlations between E and DAP were found for all procedures, with R2 coefficients ranging from 0.80 (abdominal angiography) to 0.99 (biliary stent insertion, Nephrostomy and TIPS). The DAP values obtained in this study showed general consistency with the values provided in the literature and median E values ranged from 4.0 mSv (biliary drainage) to 49.6 mSv (TIPS).

Conclusions:

Values of E/DAP conversion factors were derived for each procedure from a comprehensive analysis of projection and dosimetric data: they could provide a good evaluation for the stochastic effects. These results can be obtained by means of a close cooperation between different interventional professionals involved in patient care and dose optimization.
Mechanical Control of Morphogenesis by Fat/Dachsous/Four-Jointed Planar Cell Polarity Pathway
Authors: Bosveld Floris , Bonnet Isabelle , Guirao Boris , Tlili Sham , Wang Zhimin , Petitalot Ambre , Marchand Raphaël , Bardet Pierre-Luc , Marcq Philippe , Graner François , Bellaïche Yohanns
Published: April 2012

The Right Move

During development, epithelial tissues deform to give rise to functional tissues and organs. How gene expression controls local cell mechanical properties to drive tissue deformation remains poorly understood.

Bosveld
et al.

(p.
724
, published online 12 April) have uncovered how the conserved Fat/Dachsous/Four-jointed signaling pathway controls local mechanical cell properties to generate global tissue contraction in
Drosophila
epithelial tissue.
Differential Diffusivity of Nodal and Lefty Underlies a Reaction-Diffusion Patterning System
Authors: Müller Patrick , Rogers Katherine W. , Jordan Ben M. , Lee Joon S. , Robson Drew , Ramanathan Sharad , Schier Alexander F.
Published: April 2012

Reaction-Diffusion Patterning

Six decades ago, Alan Turing proposed the reaction-diffusion model to explain how complex patterns emerge during morphogenesis. In this model, an activator activates both itself and an inhibitor (the “reaction”), with the activator being less mobile than the inhibitor (“diffusion”). Many activator/inhibitor pairs have been described, but the role of differential mobility versus differential clearance of activators and inhibitors is often unclear. Now,

Müller
et al.

(p.
721
, published online 12 April) show that during zebrafish embryogenesis, the activator Nodal has lower diffusivity than the inhibitor Lefty, while both molecules are cleared at similar rates, which supports the idea that Nodal and Lefty form a classical reaction-diffusion system.
2011 Sino-American Symposium on Clinical and Translational Medicine
Authors: Sanders Sean
Published: April 2012

Prefaces:

The second annual Sino-American Symposium on Clinical and Translational Medicine was held on 24 June 2011 in Shanghai, China. It provided a forum for scientists, physicians, and officers from China and the United States to come together to discuss important issues and challenges in making quality health care accessible to all peoples.

As the Chinese Minister of Health, Dr. Zhu Chen, puts it: "The per capita expenditure on health in China is much less than that in the United States, and the two nations' health care systems are quite different. However, both countries face the same challenge: To meet the growing health needs and expectations of their citizens, while facing an increasingly restrictive financing environment. We think that translational medicine is one of the best solutions to tackle this challenge."

This booklet, produced as a special sponsored supplement to
Science
, collects in one volume several reports from the symposium covering a broad range of topics from pure scientific research to decision-making and policy, and accounts of the successful implementation of translational strategies and the commercialization of medical devices. It also provides a foundation for the future cooperation between China and the United States, as well as the rest of the world, on which to build a strong strategy for applying the tenants of translational medicine to the benefit of all human kind.
New advances in the molecular biology of hepatitis C virus infection: towards the identification of new treatment targets
Authors: Ploss Alexander , Dubuisson Jean
Published: April 2012

Hepatitis C virus (HCV) causes chronic infection in almost 2% of the world's population. If untreated, chronic carriers can develop severe liver disease including fibrosis, cirrhosis and hepatocellular carcinoma. Until recently, hepatitis C was treated with a combination of pegylated interferon and ribavirin, a treatment which was only partially effective and was plagued with side effects. In 2011 two inhibitors of the virally encoded NS3/4 protease have become part of standard therapy, which have improved treatment rates but can exacerbate the problematic side effects. While the addition of these first directly acting antivirals (DAAs) marks a milestone in anti-HCV therapy, new and improved combinations of drugs are desperately needed. New generations of drugs will have to address genetic variability of HCV and issues of viral resistance. Furthermore, combination therapies have to be tailored to effectively cure patient populations that have traditionally been hardest to treat, including patients with cirrhosis, those receiving liver transplants and individuals who are co-infected with HIV or hepatitis B virus. Since the discovery of HCV a plethora of experimental tools have been developed which enabled detailed analysis of various aspects of the viral life cycle and the interaction of HCV with its human host. Such studies have revealed a growing list of targets for therapeutic intervention, some of which will be discussed in this review.
New insight in the pathobiology of hepatitis B virus infection
Authors: Dandri Maura , Locarnini Stephen
Published: April 2012

Chronic hepatitis B virus (HBV) infection remains a major health burden and the main risk factor for the development of hepatocellular carcinoma worldwide. However, HBV is not directly cytopathic and liver injury appears to be mostly caused by repeated attempts of the host's immune responses to control the infection. Recent studies have shown that the unique replication strategy adopted by HBV enables it to survive within the infected hepatocyte while complex virus–host interplays ensure the virus is able to fulfil its replication requirements yet is still able to evade important host antiviral innate immune responses. Clearer understanding of the host and viral mechanisms affecting HBV replication and persistence is necessary to design more effective therapeutic strategies aimed at improving the management of patients with chronic HBV infection to eventually achieve viral eradication. This article focuses on summarising the current knowledge of factors influencing the course of HBV infection, giving emphasis on the use of novel assays and quantitative serological and intrahepatic biomarkers as tools for predicting treatment response and disease progression.