bluuebunny/crossref_metadata_2025 huggingface dataset:
Lytic bone lesions suspected for metastasis: Ultrasonically guided fine‐needle aspiration biopsy
Authors: Civardi Giuseppe , Livraghi Tito , Colombo Paolo , Fornari Fabio , Cavanna Luigi , Buscarini Luigi
Published: February 2007

Ultrasonically guided fine‐needle aspiration biopsy (US‐FNAB) was performed in 30 patients with a lytic bone lesion suspected for metastasis detected by conventional radiological examinations. The patients were selected for US‐FNAB on the basis of the ability of the ultrasound examination to clearly visualize the lesion. The cytological diagnosis was confirmed at surgery in 3 cases, and at clinical and radiological follow‐up after more than 6 months in the remaining cases. The lesions were located mostly in the thoracic skeleton (ribs and sternum) and pelvic bone. We diagnosed malignancy in 26 cases and benign lesions in 2 cases. An inadequate sample was obtained in 1 case, and 1 case yielded a false‐negative result. According to these results, we obtained a sensitivity of 93%. We conclude that ultrasonically guided fine‐needle aspiration biopsy is a useful technique to obtain a pathological diagnosis in cases of lytic bone lesions that can be visualized with this imaging technique. © 1994 John Wiley & Sons, Inc.
Failed or difficult laparoscopic cholecystectomy: Can preoperative ultrasonography identify potential problems?
Authors: Carmody Eamonn , Arenson Ann‐Marie , Hanna Sharif
Published: February 2007

A prospective study was performed to assess the role of preoperative ultrasonography in predicting failed or difficult laparoscopic cholecystectomy. Fifty patients underwent detailed preoperative ultrasound examinations. The number and size of calculi, evidence of acute or chronic cholecystitis, gallbladder morphology, and the presence or absence of aberrant anatomy were documented. A comparison was made of the surgical outcome and the ultrasound findings in each patient.

Six patients were converted to open cholecystectomy because of inflammatory changes in the gallbladder. The preoperative ultrasound studies in 5 of these patients demonstrated evidence of cholecystitis and cholelithiasis. Gallbladder wall thickening and contraction were also seen. Five gallbladder resections had intraoperative difficulties; preoperative ultrasonography demonstrated a thickened gallbladder wall in 2. Of 31 uneventful cases, 7 had evidence of gallbladder wall thickening and/or contraction. There were no ultrasound features that identified between the unsuccessful, difficult, or uneventful laparoscopic cholecystectomies.

We conclude that detailed preoperative ultrasound evaluation of the gallbladder in patients destined for laparoscopic cholecystectomy is of little value in screening for difficult or unsuitable cases. © 1994 John Wiley & Sons, Inc.
Contribution of transcranial color‐coded real‐time sonography to the etiopathogenetic classification of middle cerebral artery stenosis
Authors: Becker Georg , Lindner Alfred , Hofmann Erich , Bogdahn Ulrich
Published: February 2007

Transcranial color‐coded real‐time sonography (TCCS) and cranial computed tomography were applied to patients with middle cerebral artery (MCA) stenosis to evaluate whether these techniques may disclose additional aspects of the pathophysiology of the stenotic lesion. In 15 patients with MCA stenosis identified by transcranial Doppler sonography, the echogenicity of the stenotic segment was estimated subjectively by TCCS. The density of the stenotic segment, prior to being detected by TCCS, was quantified by computed tomography. In 5 of the 15 patients, transcranial image‐directed Doppler sonography identified a hyperechogenic lesion in association with the stenotic vascular segment; computed tomography demonstrated a “dense” artery (Hounsfield units [HU] > 120) in the corresponding vascular segment. In 10 patients the echogenicity of the stenotic segment was found to be normal, with a computed tomography density of >100 HU in the corresponding segment. Hyperechogenic and hyperdense stenotic vascular segments in TCCS and computed tomography, respectively, may indicate an arteriosclerotic vascular lesion with calcium deposits. Normal echogenicity and normal to slightly elevated computed tomography‐density of a stenotic vascular segment may suggest the presence of a thrombotic/embolic lesion. © 1994 John Wiley & Sons, Inc.
Color Doppler ultrasonography and serum CA 125 in the differentiation of benign and malignant ovarian tumors
Authors: Chou Cheng‐Yang , Chang Chiung Hsin , Yao Bor‐Lin , Kuo Hong‐Chang
Published: February 2007

Color Doppler ultrasonography and serum CA 125 were used to evaluate 114 adnexal tumors prior to surgery. Six patients were excluded from this study because of ovarian cancer, borderline ovarian malignancy, and tubal gestation. A total of 108 patients were eligible: 83 patients with benign and 25 patients with malignant ovarian tumors. Resistance index (RI) was used to determine the peripheral resistance of intratumoral vessels. The cutoff point for the RI was defined as 0.5. The blood flow was considered to be normal when the RI was greater than 0.5 and abnormal when it was less than 0.5. The blood flow was detected in 100% of malignant tumors and 59% of benign tumors. The initial cutoff value for CA 125 was 35 U/mL. Sensitivity, specificity, positive predictive value, and negative predictive value were compared in terms of RI, serum CA 125, and a combination of the two. Our conclusion is that the combination of RI and CA 125 gives a sensitivity of 100% and negative predictive value of 100%. If the cutoff point of CA 125 was raised from 35 to 65 U/mL, then a specificity of 100% and positive predictive value of 100% were also attained with the use of RI and CA 125 without changes in sensitivity or negative predictive value. We conclude that the combination of color Doppler ultrasonography and serum CA 125 is an effective method to differentiate benign from malignant ovarian tumors. © 1994 John Wiley & Sons, Inc.
Experimental aspects of high‐intensity transient signals in the detection of emboli
Authors: Markus Hugh S. , Tegeler Charles H.
Published: February 2007

Experimental studies in the 1960s and 1970s demonstrated the high sensitivity of Doppler ultrasound in detecting gaseous bubbles. More recent studies have shown that microscopic air bubbles, as well as glass microspheres as small as 5 μ to 20 μ, cause characteristic high‐intensity signals. Recently it has been demonstrated that less echogenic embolic materials such as thrombus, platelet aggregates, and atheroma can also be detected with a high sensitivity. Such “solid,” or formed‐element, emboli as small as 200 μ to 400 μ can be detected; the lower size limit of detection was due to an inability to make smaller embolic particles rather than to the sensitivity of the detection process itself. Analysis of the Doppler signals provides some information about embolus size and composition, but accurate characterization in clinical practice is not possible using current technology. Studies in experimental models have allowed the detailed description of embolic signals; they appear as a short‐duration, frequency‐focused increase in intensity, predominantly unidirectional in the direction of flow, and usually contained within the spectral envelope. In contrast, artifacts appear as a bidirectional, high‐intensity increase with maximum intensity at low frequencies. These differences have been exploited to develop automatic embolus detection programs, and an off‐line version has been successfully validated in an experimental model. © 1995 John Wiley & Sons, Inc.
Cerebrovascular regulation and vasoneuronal coupling
Authors: Daffertshofer M. , Hennerici M.
Published: February 2007

Maintenance of cerebral perfusion pressure is a prerequisite for the prevention of cerebral ischemia. Physiological fluctuations in systemic perfusion pressure are compensated by cerebrovascular autoregulation. Cerebral hypoperfusion could result from (1) systemic hemodynamic failure (eg, distal to severe arterial stenosis), overcharging the vasoregulatory capacity; (2) dysfunction and exhaustion of cerebrovascular autoregulation; or (3) both.

Ultrasound offers an excellent temporal resolution, is noninvasive, and is easily applicable for follow‐up investigations. Despite its poor spatial resolution, transcranial Doppler sonography has been used for determination of cerebral perfusion reserve studies measuring cerebral blood flow velocity (CBFV) during hypercapnia or application of vasoactive agents (eg, acetazolamide). This approach evaluates vasomotor regulation in patients with hemodynamic compromise distal to severe stenosis or occlusion of the brain supplying arteries.

Monitoring CBFV during tilt table examinations directly measures cerebral autoregulation. In patients with systemic orthostatic hypotension, maintainance or failure of cerebrovascular compensation and, even more importantly, cerebrovascular dysautoregulation, despite normal systemic blood pressure regulation, may be demonstrated.

Vasoneuronal coupling is reflected by CBFV variations during appropriate neuronal stimulation. Neuronal dysfunction is associated with CBFV abnormalities as exemplified by preconditions of focal cerebral dysfunction in the posterior cerebral artery (PCA) in migraineurs with aura, where massive alteration of vasoneuronal coupling and ischemia is threatening during spreading depression. A highly significant asymmetric gain of vasoneuronal coupling in the interictal state may act as a trigger mechanism in these patients.

Testing for vasoneuronal coupling within the middle cerebral artery (MCA) territory is more difficult due to the poor spatial resolution with various neuronal stimuli (eg, motorsensory or cognitive paradigms), only eliciting local neuronal areas underrepresented in the MCA CBFV global changes. However, motor stimulation evoked CBFV may be used to indicate dysintegation of vasoneuronal coupling in the course of acute cerebral ischemia with sensorimotor hemiparesis and, moreover, seems to be of prognostic value regarding the motor deficit. © 1995 John Wiley & Sons, Inc.
New and future developments in cerebrovascular ultrasound, magnetic resonance angiography, and related techniques
Authors: Meairs Stephen , Röther Joachim , Neff Wolfgang , Hennerici Michael
Published: February 2007

Four‐dimensional (4D) analysis of atherosclerotic plaque and wall motion, the application of 4D ultrasound to the study of atherogenesis, and the incorporation of ultrasound data into flow models for simulation of cerebrovascular hemodynamics are new frontiers in diagnostic ultrasound that use computer vision and optical flow techniques to exploit the full potential of real‐time imaging and Doppler studies. New approaches to improve blood vessel delineation with ultrasound include application of contrast agents, harmonic imaging, and red blood cell density imaging. An assessment of the potential clinical utility of these new developments in cerebrovascular ultrasound requires an analysis of comparable trends in magnetic resonance (MR) technology, eg, rapid advances in the fields of MR angiography, dynamic contrast‐enhanced MR, and MR diffusion imaging. Likewise, the value of ultrasound techniques for the measurement of blood flow to evaluate cerebrovascular hemodynamics must be compared to related methods in magnetic resonance, such as dynamic MR inflow tracking. This article addresses several new and future developments in cerebrovascular ultrasound and discusses their relative merits in terms of ongoing research in the field of magnetic resonance angiography, imaging, and related techniques. © 1995 John Wiley & Sons, Inc.
Gallbladder wall thickening in dengue hemorrhagic fever: An ultrasonographic study
Authors: Setiawan Melani W. , Samsi Tatang K. , Pool Thomas N. , Sugianto D. , Wulur H.
Published: February 2007

This study attempts to investigate whether gallbladder wall thickening (GBWT) measured by ultrasonography can be used in children as a reliable criterion to predict the onset of severe dengue hemorrhage fever (DHF). In this prospective study, we performed ultrasound examinations focusing on the gallbladder wall and the presence of intraperitoneal free fluid in 48 mild DHF cases (grades I–II) and 48 severe cases (grades III–IV). GBWT varied between 1 mm and 8 mm with a mean of 3.77 mm ± 2.04 mm. The mean value of DHF grades I and II (2.39 mm ± 1.48 mm) is significantly lower than that of grades III and IV (5.14 mm ± 1.54 mm), p < 0.001. GBWT exceeded 3 mm in only 16 of 48 (33.3%) grade I–II patients and in 45 of 48 (93.8%) grade III–IV patients. A significant positive correlation was apparent between GBWT and the severity of illness, p < 0.001. Patients with ascites have significantly thicker gallbladder walls than those without, p < 0.01. In clinically confirmed DHF cases, the sonographic finding of GBWT >3 mm to 5 mm, with 93.8% sensitivity, can be used as a criterion indicating the need for admission and monitoring. A GBWT of ⩾5 mm, with 91.7% specificity, is useful as a criterion for identifying DHF patients at high risk of developing hypovolemic shock. © 1995 John Wiley & Sons, Inc.
Pylorus subjacent to the gallbladder: An additional finding in hypertrophic pyloric stenosis
Authors: Levine Deborah , Wilkes David C. , Filly Roy A.
Published: February 2007

We have noted that sonographically positive cases of hypertrophic pyloric stenosis (HPS) demonstrate a distortion of normal anatomy in which the elongated pylorus displaces the duodenum and lies adjacent to and below the gallbladder. Ten consecutive cases of HPS diagnosed by ultrasound were reviewed. In each case the pylorus was imaged subjacent to the gallbladder. Sonograms from 100 infants from a different institution were then reviewed. There were 13 cases with the pylorus subjacent to the gallbladder, 12 of these met criteria for HPS. Recognition of this anatomic relationship may aid in the diagnosis of HPS. © 1995 John Wiley & Sons, Inc.
Flow reversal in the right anterior branch of the portal vein: “Bicolor portal vein” color Doppler analysis
Authors: Donoso Lluís , Parellada J. Antoni , Martínez‐Noguera Antonio , Sanchís Eduard , Sabaté Josep M.
Published: February 2007

The purpose of this study is to describe a phenomenon of bidirectional flow, “bicolor portal vein” (BPV), within the right anterior branch of the portal vein (RAPV), with color Doppler imaging (CDI). We prospectively studied with CDI the intrahepatic portal vein and its branches in 316 consecutive patients in search of areas of nonlaminar flow within the RAPV. Forty patients were excluded from the study due to varied conditions that precluded an accurate CDI study. A prospective design allowed us to record the frequency of appearance, systematically measure a set of parameters in each patient, and establish different groups for comparison.

We found an area of BPV within the RAPV in six patients. Five of them had a history of liver disease (8.2% of the patients with known liver disease). The BPV was consistently portrayed as a well‐defined blue oval‐shaped area of flow reversal attached to the medial side of the RAPV immediately before its bifurcation, suggesting a rotary motion of blood. All six patients presented a transverse diameter of the RAPV significantly larger than the rest of the patients (p < 0.05). Furthermore, blood flow measurements within the RAPV of the six patients with BPV were found to be significantly higher when compared with the rest of the patients (<0.05).

Knowledge of the possible presence of a BPV within the RAPV can prevent diagnostic confusion with reversal of flow, a truly pathologic condition related to liver disease. © 1995 John Wiley & Sons, Inc.
Degenerated uterine leiomyoma mimicking acute appendicitis: Sonographic diagnosis
Authors: Yacoe Marshall E. , Jeffrey R. Brooke
Published: February 2007

The present study reviews four cases in which degenerated uterine leiomyomas mimicked appendicitis clinically. The correct diagnosis was made prospectively by sonography in each case. Appendicitis was excluded by graded compression sonography and an exophytic uterine leiomyoma was identified at the point of maximal symptoms. The leiomyomas demonstrated central hypoechoic foci, but no detectable Doppler flow indicating necrosis. Although the phenomenon of a degenerated uterine leiomyoma mimicking appendicitis clinically is known, sonographic diagnosis has not been reported previously. The importance of making this diagnosis sonographically is that management of a degenerated leiomyoma is conservative and unnecessary surgery could be avoided. © 1995 John Wiley & Sons, Inc.
Ultrasound‐guided fine‐needle aspiration biopsy of solitary pulmonary nodules
Authors: Chen Chi‐Chiang , Hsu Wu‐Huei , Huang Chih‐Mei , Chen Chih‐Yi , Kwan Po‐Cheung , Chiang Chi‐Der
Published: February 2007

Ultrasound‐guided fine‐needle aspiration biopsy (US‐guided FNAB) was performed in 40 patients with solitary pulmonary nodules (SPNs) for evaluation of diagnostic results and complication rates. The final diagnoses of the 40 patients included 30 malignancies and 10 benign lesions. Using US‐guided FNAB, the diagnostic yields were 97% (29/30) in malignancies and 60% (6/10) in benign lesions. Of the 29 patients with cytologically proven malignancies, 12 underwent surgical resection. The correlation between cytological results and histologic diagnoses in these 12 was excellent (100%). The size of the nodule did not affect the diagnostic rate or complication rate. Only two patients (5%) developed minimal pneumothorax after US‐guided FNAB. We conclude that US‐guided FNAB is a useful, safe, and convenient diagnostic tool for SPN, and that malignant pulmonary nodules are more easily diagnosed than benign nodules. © 1995 John Wiley & Sons, Inc.
Cardiovascular effects of noradrenaline microinjection in the bed nucleus of the stria terminalis of the rat brain
Authors: Crestani C.C. , Alves F.H.F. , Resstel L.B.M. , Corrêa F.M.A.
Published: February 2007

The bed nucleus of the stria terminalis (BST) is a limbic structure involved in regulating the hypothalamic‐pituitary‐adrenal axis as well as in central cardiovascular control. We report here on cardiovascular effects caused by microinjection of noradrenaline (NA) in the BST of the rat brain and the peripheral mechanisms involved in their mediation. Injection of NA (3, 7, 10, 15, 30, or 45 nmol in 100 nl) in the BST of unanesthetized rats caused long‐lasting dose‐related pressor and bradycardiac responses. No responses were observed when the dose of 10 nmol NA was microinjected into surrounding structures, such as the anterior commissure, the stria terminalis, the fornix, and the internal capsule, indicating a predominant action at the BST. Additionally, microinjection of 50 nmol tyramine, an indirectly acting sympathomimetic amine, caused similar pressor response, indicating local NA release in the BST. Responses to NA microinjection in the BST were markedly reduced in urethane‐anesthetized rats, favoring the idea of a central action without significant leakage to the peripheral circulation. The pressor response was potentiated by i.v. pretreatment with the ganglion blocker pentolinium and blocked by i.v. pretreatment with the selective V1‐vasopressin antagonist dTyr(CH2)5(Me)AVP, suggesting its mediation by vasopressin release into circulation. The bradycardiac response to NA microinjected into the BST was also abolished by pretreatment with the vasopressin antagonist, indicating its reflex origin. In conclusion, results indicate that microinjection of NA into the BST evokes pressor responses, which are mediated by acute vasopressin release. © 2007 Wiley‐Liss, Inc.
Medicinal plant species with potential antidiabetic properties
Authors: Mentreddy Srinivasa Rao
Published: February 2007

Diabetes mellitus is one of the world's major diseases. It currently affects an estimated 143 million people worldwide and the number is growing rapidly. In the USA alone, about 20.8 million or 7% of the population suffer from diabetes or related complications. The estimated direct and indirect costs of diabetes exceed US$ 132 billion annually. Plant‐based medicinal products have been known since ancient times, and several medicinal plants and their products (active natural principles and crude extracts) have been used to control diabetes in the traditional medicinal systems of many cultures worldwide, including those of the Asian Indians, Chinese and South Americans. A limited number of these plant species have been studied and validated for their hypoglycaemic properties using diabetic animal models and in clinical studies using human subjects. Several oral hypoglycaemic agents are the primary forms of treatment for diabetes. However, prominent side‐effects of such drugs are the main reason for an increasing number of people seeking alternative therapies that may have less severe or no side‐effects. Thus plant‐based herbal drugs or botanicals are emerging as the primary components of holistic approaches to diabetes management. In this review, selected species that have been validated for their hypoglycaemic or antihyperglycaemic properties using laboratory diabetic animal models and in clinical trials using human subjects, and reported in refereed journals are presented. Copyright © 2007 Society of Chemical Industry
Ring‐opening polymerization of epoxy end‐terminated poly(ethylene oxide) as a route to highly crosslinked materials with exceptional swelling behavior (II)
Authors: Laine Richard M , Kim Seung Gyoo , Rush Jason , Mollan Mathew , Sun Hei‐Jen , Lodaya Mayur
Published: February 2007

Highly swellable poly(ethylene oxide) (PEO) gels were prepared by anionic ring‐opening polymerization of diepoxy end‐capped PEO (3400 g mol−1) and PEO (8000 g mol−1) using dianionic glycerol and glycolic acid initiators at scales of up to 50 g diepoxide. The glycerol‐derived materials swell to almost 20 times their mass in water. The driving force for rapid swelling appears to arise during ‘crystallization’, as segments between crosslinks are forced to pack under conditions that create high‐energy domains within the material. Solvation and therefore swelling are driven by the release of the resulting packing energy. These observations may offer insight into methods for designing other highly swellable materials. When the polyfunctional initiators have groups with different reactivities (e.g. alkoxide versus carboxylate), as might be expected, the more nucleophilic functional group appears to dominate the ring‐opening polymerization process. Copyright © 2007 Society of Chemical Industry
The polyoxaesters
Authors: Andjelić Saša , Jamiolkowski Dennis D , Bezwada Rao
Published: February 2007

This paper provides a review of a new class of synthetic absorbable polyesters, the ‘polyoxaesters’. We describe what they are and provide routes of preparation to the homopolymers, as well as their copolymers with lactones. Structure–property relationships are outlined and applications with commercial potential are discussed. Finally, two potential surgical applications, suture coatings and adhesion prevention barriers, are presented in more detail. Copyright © 2007 Society of Chemical Industry
Electrochemical polymerization of pyrrole in cholesteric liquid crystals: Morphology and optical properties
Authors: Goto Hiromasa
Published: February 2007

Electrochemical polymerization in a cholesteric liquid‐crystal electrolyte was carried out. Polypyrrole thus synthesized in a cholesteric liquid‐crystal electrolyte could be clearly seen to form a specific morphology. The polypyrrole films exhibited chiroptical properties and formed various surface structures such as Schlieren, Nazca‐line, sea‐anemone, and wire‐loop structures. These structures that developed during polymerization were preserved even after washing. Moreover, no chiral molecule reacted chemically with the monomer during polymerization, and the electrolyte functioned only as a matrix chiral continuum. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1377–1387, 2007.
Outcome of pulmonary function in Lemierre's disease‐associated acute respiratory distress syndrome
Authors: Cholette Jill M. , Caserta Mary , Hardy Dwight , Connolly Heidi V.
Published: February 2007

Pulmonary function in acute respiratory distress syndrome (ARDS) survivors typically returns to normal with the exception of a persistent reduction in carbon monoxide diffusion capacity (DLco). Septic thrombophlebitis of the internal jugular vein, (Lemierre's syndrome or postanginal sepsis) is a well‐described, albeit uncommon cause of ARDS in which metastatic pulmonary thromboemboli precipitate respiratory failure requiring ventilatory support. We describe convalescent pulmonary function in two survivors of Lemierre's disease‐associated ARDS, suggesting that the subset of Lemierre's syndrome induced ARDS survivors have an excellent long‐term pulmonary prognosis. Pediatr Pulmonol. 2007; 42:389–392. © 2007 Wiley‐Liss, Inc.
Use of a structural analogue versus a stable isotope labeled internal standard for the quantification of angiotensin IV in rat brain dialysates using nano‐liquid chromatography/tandem mass spectrometry
Authors: Lanckmans Katrien , Sarre Sophie , Smolders Ilse , Michotte Yvette
Published: February 2007

Quantifying low concentrations of neuropeptides in microdialysates requires a selective and sensitive analysis technique, such as nano‐liquid chromatography/electrospray ionization tandem mass spectrometry (nanoLC/ESI‐MS/MS). However, we observed reduced accuracy of the method due to matrix effects. Indeed, ESI‐MS detection is known to be sensitive to matrix effects. Moreover, dialysates are complex mixtures of small molecules, peptides and other matrix compounds that can influence the ionization efficiency of the neuropeptide of interest and the stability of the peptide in the samples. In the study reported in this paper, we investigated whether the use of an internal standard (IS) can correct for these matrix effects. As a model compound for neuropeptides we used angiotensin IV (Ang IV). We compared the use of a structural analogue (norleucine1‐Ang IV) with a stable isotope labeled (SIL) analogue. Linearity of the method was improved when either of the proposed ISs were applied. Only when using the SIL‐IS could the repeatability of injection and the method's precision and accuracy be improved. Finally, the IS was able to correct for degradation of Ang IV in dialysates, prolonging the possible storage period of the samples. We conclude that the structural analogue is not suited as an IS and that the application of a SIL analogue is indispensable when quantifying Ang IV in dialysates using nanoLC/ESI‐MS/MS detection. Copyright © 2007 John Wiley & Sons, Ltd.
On the Production of X‐rays by Low Energy Ion Beams
Authors: Joy David C. , Meyer Harry M. , Bolorizadeh Mehdi , Lin Yinghong , Newbury Dale
Published: February 2007

Although electron beams with energies of a few keV can excite fluorescent X‐ray production from solids, ion beams of comparable energy cannot do so. The reason for this situation is that it is the velocity of the incident particle, rather than its energy, which determines whether an ionization event can be generated. SCANNING 29: 1–4, 2007. Copyright © 2007 Wiley Periodicals, Inc.
Real Imaging and Size Values of Saccharomyces cerevisiae Cells with Comparable Contrast Tuning to Two Environmental Scanning Electron Microscopy Modes
Authors: Misirli Zulal , Öner Ebru Toksoy , Kirdar Betul
Published: February 2007

The combined application of electron microscopy (EM) is frequently used for the microstructural investigation of biological specimens and plays two important roles in the quantification and in gaining an improved understanding of biological phenomena by making use of the highest resolution capability provided by EM. The possibility of imaging wet specimens in their “native” states in the environmental scanning electron microscope (ESEM) at high resolution and large depth of focus in real time is discussed in this paper. It is demonstrated here that new features can be discovered by the elimination of even the least hazardous approaches in some preparation techniques, that destroy the samples. Since the analysis conditions may influence the morphology and the extreme surface sensitivity of living biological systems, the results obtained from the same cultured cell with two different ESEM modes (Lvac mode and wet mode) were compared. This offers new opportunities compared with ESEM‐wet/Lvac‐mode imaging, since wet‐mode imaging involves a real contrast and gives an indication of the changes in cell morphology and structure required for cell viability. In this study, wet‐mode imaging was optimized using the unique ability of cell quantities for microcharacterization in situ giving very fine features of topological effects. Accordingly, the progress is reported by comparing the results of these two modes, which demonstrate interesting application details. In general, the functional comparisons have revealed that the fresh unprocessed Saccharomyces cerevisiae cells (ESEM‐wet mode) were essentially unaltered with improved and minimal specimen preparation timescales, and the optimal cell viability degree was visualized and also measured quantitatively while the cell size remained unchanged with continuous images. SCANNING 29: 11–19, 2007. Copyright © 2007 Wiley Periodicals, Inc.
Negotiating the conflicts: Reexamining the structure and function of reflection in science teacher learning
Authors: Danielowich Robert
Published: February 2007

Many researchers and teacher educators propose that reflection is an important way teachers can think about changing their views and practices. The hierarchical constructs used to describe reflection, however, are often interpreted in ways that promote reflection as a toolteachers use to elevate their views and practices toward ideal “end goals” rather than as a more complex intellectual act that could help them learn how to shape their own goals. This research explores how four early career science teachers learned to negotiate the conflicts between their own goals and actual practices by situating their reflections in multiple contexts. They were invited to become aware of those conflicts through interviews and discussions of classroom observations and then to address them by actually teaching toward their own unrealized goals. The data generated from these activities were described with a rubric based on M. van Manen's reflection construct (1977) but were framed with certain perceptions each teacher had about her or his own science teaching. Several patterns emerged across the four teachers' cases that challenge the use of reflection as a tool and suggest how science teachers can reflect as a way to take greater ownership over and responsibility for their own lifelong learning. © 2007 Wiley Periodicals, Inc. Sci Ed 91:629–663, 2007
A two‐part model for censored medical cost data
Authors: Tian Lu , Huang Jie
Published: February 2007

The two‐part model is often used to analyse medical cost data which contain a large proportion of zero cost and are highly skewed with some large costs. The total medical costs over a period of time are often censored due to incomplete follow‐up, making the analysis difficult as the censoring can be informative. We propose to apply the inverse probability weighting method on a two‐part model to analyse right‐censored cumulative medical costs with informative censoring. We also introduce a set of simple functionals based on the intermediate cost history to be applied with the efficiency augmentation technique. In addition, we propose a practical model‐checking technique based on the cumulative residuals. Simulation studies are conducted to evaluate the finite sample performance of the proposed method. We use a data set on the cardiovascular disease (CVD)‐related Medicare costs to illustrate our proposed method. Copyright © 2007 John Wiley & Sons, Ltd.
Sample size calculation with dependence adjustment for FDR‐control in microarray studies
Authors: Shao Yongzhao , Tseng Chi‐Hong
Published: February 2007

DNA microarrays have been widely used for the purpose of simultaneously monitoring a large number of gene expression levels to identify differentially expressed genes. Statistical methods for the adjustment of multiple testing have been discussed extensively in the literature. An important further challenge is the existence of dependence among test statistics due to reasons such as gene co‐regulation. To plan large‐scale genomic studies, sample size determination with appropriate adjustment for both multiple testing and potential dependency among test statistics is crucial to avoid an abundance of false‐positive results and/or serious lack of power. We introduce a general approach for calculating sample sizes for two‐way multiple comparisons in the presence of dependence among test statistics to ensure adequate overall power when the false discovery rates are controlled. The usefulness of the proposed method is demonstrated via numerical studies using both simulated data and real data from a well‐known study of leukaemia. Copyright © 2007 John Wiley & Sons, Ltd.
Hollow laser self-confined plasma for extreme ultraviolet lithography and other applications
Authors: SIZYUK V. , HASSANEIN A. , SIZYUK T.
Published: February 2007

Laser-produced plasma (LPP) devices are being developed as a light source for the extreme ultraviolet (EUV) lithography applications. One concern of such devices is to increase the conversion efficiency of laser energy to EUV light. A new idea based on the initiation and confinement of cumulative plasma jet inside a hollow laser beam is developed and simulated. The integrated computer model (HEIGHTS) was used to simulate the plasma behavior and the EUV radiation output in the LPP devices. The model takes into account plasma heat conduction and magnetohydrodynamic processes in a two-temperature approximation, as well as detailed photon radiation transport in 3D Monte Carlo model. The model employs cylindrical 2D version of a total variation-diminishing scheme (for the plasma hydrodynamics) and an implicit scheme with the sparse matrix linear solver (to describe heat conduction). Numerical simulations showed that the EUV efficiency of the proposed hollow-beam LPP device to be higher than the current standard devices.
Impulsive electric fields driven by high-intensity laser matter interactions
Authors: BORGHESI M. , KAR S. , ROMAGNANI L. , TONCIAN T. , ANTICI P. , AUDEBERT P. , BRAMBRINK E. , CECCHERINI F. , CECCHETTI C.A. , FUCHS J. , GALIMBERTI M. , GIZZI L.A. , GRISMAYER T. , LYSEIKINA T. , JUNG R. , MACCHI A. , MORA P. , OSTERHOLTZ J. , SCHIAVI A. , WILLI O.
Published: February 2007

The interaction of high-intensity laser pulses with matter releases instantaneously ultra-large currents of highly energetic electrons, leading to the generation of highly-transient, large-amplitude electric and magnetic fields. We report results of recent experiments in which such charge dynamics have been studied by using proton probing techniques able to provide maps of the electrostatic fields with high spatial and temporal resolution. The dynamics of ponderomotive channeling in underdense plasmas have been studied in this way, as also the processes of Debye sheath formation and MeV ion front expansion at the rear of laser-irradiated thin metallic foils. Laser-driven impulsive fields at the surface of solid targets can be applied for energy-selective ion beam focusing.
Phylogenetic and morphological analysis of Antarctic lichen-forming Usnea species in the group Neuropogon
Authors: Seymour Fabian A. , Crittenden Peter D. , Wirtz Nora , Øvstedal Dag O. , Dyer Paul S. , Lumbsch H. Thorsten
Published: February 2007

Usnea species of the Neuropogon group are amongst the most widespread and abundant macrolichens in Antarctic regions. Four principal species, U. antarctica, U. aurantiaco-atra, U. sphacelata and U. subantarctica, have been described on morphological grounds. However, identification to species level is often difficult and atypical morphologies frequently arise. Over 400 specimens were collected on the Antarctic Peninsula and Falkland Islands. Both morphological and molecular characters (ITS and RPB1) were used to compare samples to clarify taxonomic relationships. Morphological characteristics used included presence of apothecia, apothecial rays, soredia, papillae, fibrils, pigmentation and the diameter of the central axis as a proportion of branch diameter. Results revealed a very close relationship between U. antarctica and U. aurantiaco-atra, suggesting that they might constitute a species pair or be conspecific. Usnea sphacelata was comprised of at least two genetically distinct groups with no clear differences in morphology. One group included the first reported fertile specimen of this species. Usnea subantarctica was phylogenetically distinct from the other main Antarctic Usnea species, but clustered with U. trachycarpa. Genetic variation was evident within all species although there was no clear correlation between geographic origin and genetic relatedness. Phylogenetic analyses indicated that species circumscription in the Neuropogon group needs revision, with the principal species being non-monophyletic. None of the morphological characters, or groups of characters, used in this study proved to be completely unambiguous markers for a single species. However, axis thickness was supported as being informative for the identification of monophyletic lineages within the group.
Radiation-induced racemization and amplification of chirality: implications for comets and meteorites
Authors: Cataldo Franco
Published: February 2007

The action of high-energy radiation on prebiotic chiral molecules plays against the preservation of chirality. Chiral molecules incorporated in comets and meteorites are bombarded for billions of years by cosmic rays and by the high-energy radiation due to the decay of naturally occurring radionuclides. The action of cosmic rays on the surface of comets and meteorites causes the complete radiation processing of the surface of these bodies, but at depths of 20 m or so the cosmic rays are completely shielded and the radiation should derive only from the decay of radionuclides. In 4.6×109 yr the radiation dose supplied by the radionuclide decay to the organic molecules present inside the cometary or meteoritic body is equivalent to 14000 kGy. Our studies on the radiolysis of a series of naturally occurring chiral molecules, the terpenes, have shown that although all undergo the radioracemization reaction, the extent of radioracemization is such that a significant fraction of chiral excess and chiral molecules can survive a radiation dose equivalent to 14000 kGy. A unique exception is represented by the terpene β-(−)-pinene which, instead of the expected radioracemization reaction, undergoes a radiation-induced polymerization. The resulting poly-β-pinene, having an highly ordered supramolecular structure, displays an optical activity which is 1.7 times higher than the starting monomer. Thus, in this specific case, the optical activity is not reduced but enhanced by the action of radiation and remains locked into a polymer which displays a considerable radiation resistance and may act as a chiral template and as a chiral surface for prebiotic chemistry.
Structure and shearing conditions in the Day Nui Con Voi massif: Implications for the evolution of the Red River shear zone in northern Vietnam
Authors: Anczkiewicz R. , Viola G. , Müntener O. , Thirlwall M. F. , Villa Igor M. , Quong Nguyen Quoc
Published: February 2007

The Day Nui Con Voi massif bears a record of the Red River shear zone (RRSZ) activity in North Vietnam. It forms a large‐scale antiformal “core complex”‐type structure, bounded by the Song Hong and Song Chay faults. The kinematics of both faults are identical and reflect transtensional shear initiated under upper amphibolite facies conditions and propagated into greenschist facies. Microfabric analysis establishes that both extensional and strike‐slip shearing initiated between 700 and 500°C. The RRSZ evolved from a single, subvertical fault, which, due to strike‐perpendicular extension, underwent progressive dilation. The created space was “intruded” by already metamorphosed and deformed ductile middle crust in the form of a gneissic “dome.” Both strike‐slip and extensional shearing were accommodated in the limbs of the antiform, while its core was uplifted from midcrustal level bearing only a minor record of sinistral shear.
Self-similar ablative flow of nonstationary accelerating foil due to nonlinear heat conduction
Authors: Murakami M. , Sakaiya T. , Sanz J.
Published: February 2007

Ablating plasma flow of an accelerating foil driven by nonlinear heat conduction is investigated theoretically. It is shown that the hydrodynamic system admits a new self-similar solution describing the nonstationary ablation process, through which the payload mass decreases to burn out at the end. In contrast to previous analyses based on stationary flow, the present solution provides a practical physical picture with a finite peak density and a distinct vacuum boundary at the front. The system is solved as a novel eigenvalue problem such that the acceleration and the heat conductivity are restrictive with each other under the self-similar evolution. Scaling laws are obtained to describe the temporal evolution for the shell acceleration and such ablation performances as the mass ablation rate and the ablation pressure.
Femtosecond dynamics of Cu(CD3OD)
Authors: Barbera Jack , Horvath Samantha , Dribinski Vladimir , McCoy Anne B. , Lineberger W. Carl
Published: February 2007

We report the femtosecond nuclear dynamics of Cu(CD3OD) van der Waals clusters, investigated using photodetachment-photoionization spectroscopy. Photodetachment of an electron from Cu−(CD3OD) with a 150fs, 398nm laser pulse produces a vibrationally excited neutral complex that undergoes ligand reorientation and dissociation. The dynamics of Cu(CD3OD) on the neutral surface is interrogated by delayed femtosecond resonant two-photon ionization. Analysis of the resulting time-dependent signals indicates that the nascent Cu(CD3OD) complex dissociates on two distinct time scales of 3 and 30ps. To understand the origins of the observed time scales, complimentary studies were performed. These included measurement of the photoelectron spectrum of Cu−(CD3OD) as well as a series of calculations of the structure and the electronic and vibrational energies of the anion and neutral complexes. Based on the comparisons of the experimental and calculated results for Cu(CD3OD) with those obtained from earlier studies of Cu(H2O), we conclude that the 3ps time scale reflects the energy transfer from the rotation of CD3OD in the complex to the dissociation coordinate, while the 30ps time scale reflects the energy transfer from the excited methyl torsion states to the dissociation coordinate.
Symmetry-adapted-cluster/symmetry-adapted-cluster configuration interaction methodology extended to giant molecular systems: Ring molecular crystals
Authors: Nakatsuji Hiroshi , Miyahara Tomoo , Fukuda Ryoichi
Published: February 2007

The symmetry adapted cluster (SAC)/symmetry adapted cluster configuration interaction (SAC-CI) methodology for the ground, excited, ionized, and electron-attached states of molecules was extended to giant molecular systems. The size extensivity of energy and the size intensivity of excitation energy are very important for doing quantitative chemical studies of giant molecular systems and are designed to be satisfied in the present giant SAC/SAC-CI method. The first extension was made to giant molecular crystals composed of the same molecular species. The reference wave function was defined by introducing monomer-localized canonical molecular orbitals (ml-CMO’s), which were obtained from the Hartree-Fock orbitals of a tetramer or a larger oligomer within the electrostatic field of the other part of the crystal. In the SAC/SAC-CI calculations, all the necessary integrals were obtained after the integral transformation with the ml-CMO’s of the neighboring dimer. Only singles and doubles excitations within each neighboring dimer were considered as linked operators, and perturbation selection was done to choose only important operators. Almost all the important unlinked terms generated from the selected linked operators were included: the unlinked terms are important for keeping size extensivity and size intensivity. Some test calculations were carried out for the ring crystals of up to 10 000-mer, confirming the size extensivity and size intensivity of the calculated results and the efficiency of the giant method in comparison with the standard method available in GAUSSIAN 03. Then, the method was applied to the ring crystals of ethylene and water 50-mers, and formaldehyde 50-, 100-, and 500-mers. The potential energy curves of the ground state and the polarization and electron-transfer-type excited states were calculated for the intermonomer distances of 2.8–100Å. Several interesting behaviors were reported, showing the potentiality of the present giant SAC/SAC-CI method for molecular engineering.
Laboratory arrangement for soft x-ray zone plate efficiency measurements
Authors: Bertilson Michael C. , Takman Per A. C. , Holmberg Anders , Vogt Ulrich , Hertz Hans M.
Published: February 2007

We demonstrate a laboratory-scale arrangement for rapid and accurate measurements of the absolute and local efficiency of soft x-ray micro zone plates in the water window. This in-house instrument is based on a single-line λ=2.88nm liquid-jet laser-plasma source. Measurements are performed by a simultaneous comparison of first diffraction-order photon flux with the flux in a calibrated reference signal. This arrangement eliminates existing source emission fluctuations. The performance of the method is demonstrated by the result from measurements of two ∼55μm diameter nickel micro zone plates, showing a groove efficiency of 12.9%±1.1% and 11.7%±1.0%. Furthermore, we show that spatially resolved efficiency mapping is an effective tool for a detailed characterization of local zone plate properties. Thus, this laboratory-scale instrument allows rapid feedback to the fabrication process which is important for future improvements.
Phase change behaviors of Sn-doped Ge–Sb–Te material
Authors: Song W. D. , Shi L. P. , Miao X. S. , Chong T. C.
Published: February 2007

Sn-doped Ge–Sb–Te material was prepared by laser synthesis. It has a rocksalt crystal structure for Sn doping content less than 30at.%. A phase change temperature tester was developed to in situ measure crystallization temperature and melting point of Sn-doped Ge–Sb–Te. The crystalliza-tion temperature of Sn-doped Ge–Sb–Te is close to that of Ge2Sb2Te5 while its melting point is much lower than that of Ge2Sb2Te5. The melting points of Sn9.8Ge20.3Sb28.4Te41.5 and Sn18.8Ge19.5Sb25.3Te36.4 are 475 and 450°C, respectively. The crystallization speed was tested by an ultraviolet light at pulse duration of 30ns. It exhibits a high crystallization speed.
First-principles calculation on the conductance of a single 1,4-diisocyanatobenzene molecule with single-walled carbon nanotubes as the electrodes
Authors: Qian Zekan , Hou Shimin , Ning Jing , Li Rui , Shen Ziyong , Zhao Xingyu , Xue Zengquan
Published: February 2007

The conductance of a single 1,4-diisocyanatobenzene molecule sandwiched between two single-walled carbon nanotube (SWCNT) electrodes are studied using a fully self-consistent ab initio approach which combines nonequilibrium Green’s function formalism with density functional theory calculations. Several metallic zigzag and armchair SWCNTs with different diameters are used as electrodes; dangling bonds at their open ends are terminated with hydrogen atoms. Within the energy range of a few eV of the Fermi energy, all the SWCNT electrodes couple strongly only with the frontier molecular orbitals that are related to nonlocal π bonds. Although the chirality of SWCNT electrodes has significant influences on this coupling and thus the molecular conductance, the diameter of electrodes, the distance, and the torsion angle between electrodes have only minor influences on the conductance, showing the advantage of using SWCNTs as the electrodes for molecular electronic devices.