bluuebunny/crossref_metadata_2025_split huggingface dataset:
Method for rapid MRI needle tracking
Authors: Kochavi Eyal , Goldsher Dorith , Azhari Haim 
Published: April 2004

AbstractA new method for MRI needle tracking within a given two‐dimensional (2D) image slice is presented. The method is based on k‐space investigation of the difference image between the current dynamic frame and a reference frame. Using only a few central k‐lines of the difference image and a nonlinear optimization procedure, one can resolve the parameters that define the 2D sinc function that best characterizes the needle in k‐space. The spatial location and orientation of the needle are determined from these parameters. Rapid needle tracking is obtained by repeated acquisitions of the same set of several central k‐lines (as in a “keyhole” protocol) and repeated computation of these parameters. The calculated needle tip is depicted on the reference image by means of a graphic overlay. The procedure was tested in computer simulations and in actual MRI scans (the computations were done offline). It was demonstrated that six k‐lines out of 128 usually suffice to locate the needle. The refresh rate of the needle location depends on the time required to sample the subset of k‐lines, calculate the current needle location, and refresh the reference image. Magn Reson Med 51:1083–1087, 2004. © 2004 Wiley‐Liss, Inc.
Comparison of BOLD contrast and Gd‐DTPA dynamic contrast‐enhanced imaging in rat prostate tumor
Authors: Jiang Lan , Zhao Dawen , Constantinescu Anca , Mason Ralph P. 
Published: April 2004

AbstractThe microcirculation and oxygenation of a tumor play important roles in its responsiveness to cytotoxic treatment, and noninvasive assessments of its vascular properties may have prognostic value. Dynamic contrast‐enhanced (DCE) 1H MRI based on infusion of Gd‐DTPA, and blood oxygen level‐dependent (BOLD) contrast based on altering inhaled gas are both sensitive to vascular characteristics. This study compares the effects observed in eight Dunning prostate R3327‐AT1 rat tumors imaged sequentially at 4.7 Tesla by echo‐planar imaging (EPI). Both interventions generated a significant response, and each revealed significant differences between the center and periphery of the tumors. On a voxel‐by‐voxel basis across the whole tumor population, there was a close correlation between the maximum rate of signal response and the magnitude of response to each intervention (R2 ≥ 0.6, P < 0.0001). However, when the data were analyzed separately for each individual tumor, some showed a weak correlation (R2 < 0.4), particularly for DCE, and the nature (slope) varied between separate tumors. Generally, there was a weak correlation (N = 7, R2 < 0.5) between responses to the two interventions on a tumor‐by‐tumor basis, which emphasizes that the techniques are not equivalent. Both techniques revealed intra‐ and intertumor heterogeneity, but the BOLD response was more rapidly reversible than the DCE response. This suggests that the BOLD technique may be a useful tool for investigating interventions (such as drugs) that cause vascular disruption. Magn Reson Med 51:953–960, 2004. © 2004 Wiley‐Liss, Inc.
Characterizing non‐gaussian diffusion by using generalized diffusion tensors
Authors: Liu Chunlei , Bammer Roland , Acar Burak , Moseley Michael E. 
Published: April 2004

AbstractDiffusion tensor imaging (DTI) is known to have a limited capability of resolving multiple fiber orientations within one voxel. This is mainly because the probability density function (PDF) for random spin displacement is non‐Gaussian in the confining environment of biological tissues and, thus, the modeling of self‐diffusion by a second‐order tensor breaks down. The statistical property of a non‐Gaussian diffusion process is characterized via the higher‐order tensor (HOT) coefficients by reconstructing the PDF of the random spin displacement. Those HOT coefficients can be determined by combining a series of complex diffusion‐weighted measurements. The signal equation for an MR diffusion experiment was investigated theoretically by generalizing Fick's law to a higher‐order partial differential equation (PDE) obtained via Kramers‐Moyal expansion. A relationship has been derived between the HOT coefficients of the PDE and the higher‐order cumulants of the random spin displacement. Monte‐Carlo simulations of diffusion in a restricted environment with different geometrical shapes were performed, and the strengths and weaknesses of both HOT and established diffusion analysis techniques were investigated. The generalized diffusion tensor formalism is capable of accurately resolving the underlying spin displacement for complex geometrical structures, of which neither conventional DTI nor diffusion‐weighted imaging at high angular resolution (HARD) is capable. The HOT method helps illuminate some of the restrictions that are characteristic of these other methods. Furthermore, a direct relationship between HOT and q‐space is also established. Magn Reson Med 51:924–937, 2004. © 2004 Wiley‐Liss, Inc.
Compound muscle action potentials during repetitive nerve stimulation
Authors: Asawa Teruko , Shindo Masaomi , Momoi Hiroki 
Published: April 2004

AbstractWhen using repetitive nerve stimulation to examine neuromuscular transmission, the change in compound muscle action potential (CMAP) size is usually assessed by measurement of negative‐peak or peak‐to‐peak amplitude. Technological developments now allow automatic measurement of CMAP area, but some patients show increment of CMAP amplitude and decrement of CMAP area. This study systematically analyzed the changes in these CMAP parameters in 23 neurologically healthy subjects. CMAPs were recorded when the ulnar nerve was stimulated at frequencies of 1, 2, 5, 10, 20, 30, and 50 HZ (five pulses per train). CMAP amplitude showed significant increment within a train when stimulus frequency was above 5 HZ (probably due to increased muscle‐fiber conduction velocity), whereas CMAP area hardly changed at any frequencies. Measurement of CMAP area produces less ambiguous results than amplitude measurement in repetitive nerve stimulation studies. Muscle Nerve 29: 724–728, 2004
Muscle‐fiber conduction velocity estimated from surface emg signals during explosive dynamic contractions
Authors: Pozzo M. , Merlo E. , Farina D. , Antonutto G. , Merletti R. , Prampero P. E. Di 
Published: April 2004

AbstractMuscle‐fiber conduction velocity (CV) was estimated from surface electromyographic (EMG) signals during isometric contractions and during short (150–200 ms), explosive, dynamic exercises. Surface EMG signals were recorded with four linear adhesive arrays from the vastus lateralis and medialis muscles of 12 healthy subjects. Isometric contractions were at linearly increasing force from 0% to 100% of the maximum. The dynamic contractions consisted of explosive efforts of the lower limb on a sledge ergometer. For the explosive contractions, muscle‐fiber CV was estimated in seven time‐windows located along the ascending time interval of the force. There was a significant correlation between CV values during the isometric ramp and explosive contractions (R = 0.75). Moreover, CV estimates increased significantly from (mean ± SD) 4.32 ± 0.46 m/s to 4.97 ± 0.45 m/s during the increasing‐force explosive task. It was concluded that CV can be estimated reliably during dynamic tasks involving fast limb movements and that, in these contractions, it may provide important information on motor‐unit control properties. Muscle Nerve 29: 823–833, 2004
Technology literature review: Quantitative sensory testing
Authors: Chong Peter Siao Tick , Cros Didier P. 
Published: April 2004

AbstractThe development of the personal computer has simplified the process of quantitating sensory thresholds using various testing algorithms. We reviewed the technical aspects and reproducibility of different methods to determine threshold for light touch‐pressure, vibration, thermal, and pain stimuli. Clinical uses and limitations of quantitative sensory testing (QST) were also reviewed. QST is a reliable psychophysical test of large‐ and small‐fiber sensory modalities. The results of QST are highly dependent on methodology and the full cooperation of the subject. QST has been shown to be reasonably reproducible over a period of days or weeks in normal subjects. The use of QST in research and patient care should be limited to instruments and their corresponding methodologies that have been shown to be reproducible. Literature data do not allow conclusions regarding the relative merits of individual QST instruments. Muscle Nerve 29: 734–747, 2004
Fracture toughness evaluation of polytetrafluoroethylene
Authors: Joyce James A. 
Published: April 2004

AbstractThe objective of this preliminary work was to explore the fracture resistance of polytetrafluoroethylene (PTFE) (DuPont tradename Teflon) as part of materials characterization work related to the development of “reactive” material projectiles. Little mechanical property data is available on this material since it is commonly used only as a coating material with the dominant properties being its low friction coefficient and high application temperature. Additional end products of the “7C” derivative, however, includes sheet, gaskets, bearing pads, piston rings, and diaphragms. In this work, standard ASTM E1820 fracture toughness specimens were machined from a 14‐mm‐thick sheet of this material obtained from NSWC Dahlgren Laboratory. These specimens were tested at three test temperatures and four test rates to determine if fracture would occur in this material, and if so, how the fracture toughness depends on the test temperature and specimen loading rate. Standard axial tensile specimens were also tested at quasi‐static and elevated loading rates at temperatures from ambient to −73°C. The major results are that while crack extension is difficult at ambient (20°C) temperature, for temperatures slightly below ambient, a rapid degradation of fracture resistance occurs. This reduction in fracture resistance is enhanced by rapid loading, and the material loses approximately 75% of its toughness (fracture energy absorption ability) at −18°C if the crack opening loading rate of the C(T) specimen approaches 0.25 m/s. Further reductions in temperature or increases in the loading rate appear to result in a reduced rate of degradation of fracture toughness.
Synthesis and properties of blue light‐emitting, silicon‐containing, regio‐ and stereoregular conjugated polymers
Authors: Sumiya Ken‐ichi , Kwak Giseop , Sanda Fumio , Masuda Toshio 
Published: April 2004

AbstractThis article concerns the hydrosilylation polyaddition of 1,4‐bis(dimethylsilyl)benzene (1) with 4,4′‐diethynylbiphenyl, 2,7‐diethynylfluorene (2b), and 2,6‐diethynylnaphthalene with RhI(PPh3)3 catalyst. Trans‐rich polymers with weight‐average molecular weights (Mw's) ranging from 19,000 to 25,000 were obtained by polyaddition in o‐Cl2C6H4 at 150–180 °C, whereas cis‐rich polymers with Mw's from 4300 to 34,000 were obtained in toluene at 0 °C–r.t. These polymers emitted blue light in 4–81% quantum yields. The cis polymers isomerized into trans polymers upon UV irradiation, whereas the trans polymers did not. The device having a layer of polymer trans‐3b obtained from 1 and 2b demonstrated electroluminescence without any dopant. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2774–2783, 2004
Synthesis and characterization of cis‐polybutadiene‐block‐syn‐polystyrene copolymers with a cyclopentadienyl titanium trichloride/modified methylaluminoxane catalyst
Authors: Ban Hoang The , Tsunogae Yasuo , Shiono Takeshi 
Published: April 2004

AbstractThis article reports a practical method for preparing cis‐polybutadiene‐block‐syn‐polystyrene (cis‐PB‐b‐syn‐PS) copolymers with long crystallizable syndiotactic polystyrene (syn‐PS) segments chemically bonded with high cis‐1,4‐polybutadiene segments through the addition of styrene (ST) to a cis‐specific 1,3‐butadiene (BD) living catalyst composed of cyclopentadienyl titanium trichloride (CpTiCl3) and modified methylaluminoxane (MMAO). The incorporation of ST into the living polybutadiene (PB) precursor remarkably depended on the polymerization temperature. A low temperature (−20 °C) suppressed the rate of ST incorporation, but a high temperature (50 °C) tended to decompose the livingness of the active species and enhance the rate of the aspecific ST polymerization initiated by MMAO. Consequently, temperatures of 0–25 °C seemed to be best for this copolymerization system. Because of the absence of ST livingness, the final products contained not only the block copolymer but also the homopolymers. Attempts to isolate the block copolymer were carried out with common solvent fractionation techniques, but the results were not sufficient. Cross‐fractionation chromatography was, therefore, used for the isolation of the cis‐PB‐b‐syn‐PS copolymer. The presence of long syn‐PS segments was confirmed by the observation of a strong endothermic peak at 260 °C in the differential scanning calorimetry curve. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2698–2704, 2004
Pessimism as a predictor of emotional morbidity one year following breast cancer surgery
Authors: Schou I. , Ekeberg Ø. , Ruland C.M. , Sandvik L. , Kåresen R. 
Published: April 2004

AbstractThe prevalence of and predictive factors for emotional morbidity (measured by the Hospital Anxiety and Depression Scale (HAD)) one year following surgery, with special focus on dispositional optimism/pessimism (measured by the Life Orientation Test (LOT‐R), was examined in 165 women, newly diagnosed with breast cancer. Patients characteristics, appraisal of cancer diagnosis, beliefs about treatment efficacy, treatment decision‐making participation, coping and emotional morbidity was assessed by self‐rating questionnaires.Prevalence of anxiety and depression cases at time of diagnosis was 34 and 12%, respectively, and 26 and 9% after one year. Prevalence of emotional morbidity was significantly enlarged among pessimists at all assessments.Pessimism was the strongest predictor for anxiety (OR: 0.86 C.I. 95% 0.77 – 0.95) and depression (OR: 0.83, C.I. 95% 0.73 – 0.95) one year following breast cancer surgery. Optimists and pessimists differed not only in regard to coping styles, but also in regards to predictors of emotional morbidity. Optimists experiencing anxiety at time of breast cancer diagnosis had about six times higher risk of experiencing anxiety after one year, compared to optimists without preoperative anxiety. For pessimists, the more pessimistic one was about one's overall future the higher risk for developing anxiety following one year of breast cancer surgery. Pessimists, who endorse helpless/hopeless coping style when receiving a diagnosis of breast cancer, had three times greater risk for experiencing depression one year after breast cancer surgery, than pessimists who did not. Health care professionals should therefore provide intervention for pessimists, as well as for patients with high anxiety scores at time of diagnosis. Copyright © 2003 John Wiley & Sons, Ltd.
Characteristics of cancer patients entering a smoking cessation program and correlates of quit motivation: implications for the development of tobacco control programs for cancer patients
Authors: Schnoll Robert A. , Rothman Randi L. , Newman Holly , Lerman Caryn , Miller Suzanne M. , Movsas Benjamin , Sherman Eric , Ridge John A. , Unger Michael , Langer Corey , Goldberg Melvyn , Scott Walter , Cheng Jonathan 
Published: April 2004

AbstractEven though survival and quality of life are adversely affected by smoking among cancer patients, about one‐third of cancer patients who smoked prior to their diagnosis continue to smoke. One barrier to the provision of smoking cessation treatments to cancer patients is the paucity of data on the characteristics of cancer patients who continue to smoke and a lack of data on correlates of quit motivation in this population. This descriptive study assessed demographic, medical, smoking history, and psychological characteristics of cancer patients in a smoking cessation program (N=111) and examined these characteristics as correlates of quit motivation. Methods used by patients to quit smoking were also queried. We found that: (1) most patients are Caucasian, married, diagnosed with head and neck (versus lung) cancer, highly addicted to nicotine, and in the contemplation or preparation stage of change; (2) most patients attempt to quit smoking without formal treatment, although 33–50% have used the transdermal nicotine patch, nicotine gum, or bupropion; (3) depressive symptoms, low quitting self‐efficacy, low perceived risk, and low perceived benefits of quitting are prevalent among patients, but most patients do not endorse the perceived disadvantages of quitting or fatalistic beliefs; and (4) quit motivation is associated with higher quitting self‐efficacy, risk perceptions, and perceived benefits of quitting, lower tobacco use and nicotine addiction, and shorter time since diagnosis. These findings can help guide the development of smoking cessation interventions for cancer patients. Copyright © 2003 John Wiley & Sons, Ltd.
Prognostic value of depressive coping and depression in survival of lung cancer patients
Authors: Faller Hermann , Schmidt Michael 
Published: April 2004

AbstractThe aim of this investigation was to determine whether depressive coping and depression predict shorter survival among lung cancer patients. We conducted a prospective study using an inception cohort with a 3–5‐year follow‐up. The sample consisted of n = 59 (of n = 69 invited to participate) patients (mean age 65 years, S.D. = 9.7; 81% male) newly diagnosed with small cell lung cancer or non‐small cell lung cancer Stage III or IV who were scheduled for later chemotherapy and/or radiotherapy at a tertiary care centre. Patients were investigated after their diagnosis and before the beginning of treatment. Depressive coping and depression were assessed using standardized self‐report questionnaires (Freiburg Questionnaire of Coping with Illness; Hospital Anxiety and Depression Scale). Depressive coping was associated with shorter survival (hazard ratio 1.75, 95% confidence interval 1.04–2.93, p = 0.034) after adjusting for age, sex, stage, histological classification, and Karnofsky performance status but not treatment type, using the Cox proportional hazards regression. Depression, however, was not linked with survival (hazard ratio 1.05, 95% confidence interval 0.98–1.13, p = 0.18). To conclude, the prognostic value of depressive coping was partially confirmed, warranting further examination of the robustness of this relationship. Copyright © 2004 John Wiley & Sons, Ltd.
Molecular analysis of WFDC1/ps20 gene in prostate cancer
Authors: Watson J.E. Vivienne , Kamkar Shervin , James Karen , Kowbel David , Andaya Armann , Paris Pamela L. , Simko Jeffry , Carroll Peter , McAlhany Stephanie , Rowley David , Collins Colin 
Published: April 2004

AbstractBACKGROUNDWFDC1/ps20 protein has been previously established as a growth suppressor of the prostate cancer cell line PC3. It maps to chromosome 16q23.1, a region of frequent loss of heterozygosity, familial association, and genomic loss in prostate cancer. We, therefore, chose to examine WFDC1/ps20 for mutations and expression changes in prostate cancer.METHODSDNA from 21 prostate cancer patients and 5 prostate cancer cell lines was screened for mutations in the WFDC1/ps20 gene by sequencing PCR products of each exon. An SphI polymorphism in the 5′ UTR was screened in 23 tumors, 22 normal adjacent prostate tissue samples, and 35 control DNAs. Expression of WFDC1/ps20 in different tissue types was examined by Northern blot and by PCR across a multi‐tissue cDNA panel. Expression patterns of WFDC1/ps20 in primary tumors were examined by full‐length RT‐PCR and products were cloned and sequenced to identify novel splice forms. Quantitative RT‐PCR analysis of WFDC1/ps20 was performed in a separate cohort of matched tumor/benign tissues.RESULTSNo tumor‐associated mutations were identified in the coding region of WFDC1/ps20. A novel polymorphism was found in exon 6 in DNA from cell lines, tumors, and normal adjacent benign tissue. A novel splice form completely deleted for exon 3 was found in tumor and normal prostate RNA. Quantitative RT‐PCR demonstrated significant down regulation of WFDC1/ps20 in prostate tumors. Subdivision of normal tissue into stromal and epithelial compartments showed that WFDC1/ps20 expression correlates exponentially with the amount of stroma present.CONCLUSIONSWFDC1/ps20 is down regulated but not frequently mutated in prostate cancer. It is expressed predominantly in the normal stroma of the prostate. We, therefore, propose that WFDC1/ps20 may not be a classical tumor suppressor gene, but might play a role in the maintenance of the normal extra cellular matrix milieu in the prostate. © 2004 Wiley‐Liss, Inc.
Establishing the benefits of research experiences for undergraduates in the sciences: First findings from a three‐year study
Authors: Seymour Elaine , Hunter Anne‐Barrie , Laursen Sandra L. , DeAntoni Tracee 
Published: April 2004

AbstractDescriptions of student‐identified benefits of undergraduate research experiences are drawn from analysis of 76 first‐round student interviews gathered at the end of summer 2000 at four participating liberal arts colleges (Grinnell, Harvey Mudd, Hope, and Wellesley). As part of the interview protocol, students commented on a checklist of possible benefits derived from the literature. They also added gains that were not on this list. Students were overwhelmingly positive: 91% of all statements referenced gains from their experiences. Few negative, ambivalent, or qualified assessments of their research experiences were offered. The benefits described were of seven different kinds. Expressed as percentages of all reported gains, they were personal/professional gains (28%); “thinking and working like a scientist” (28%); gains in various skills (19%); clarification/confirmation of career plans (including graduate school) (12%); enhanced career/graduate school preparation (9%); shifts in attitudes to learning and working as a researcher (4%); and other benefits (1%). © 2004 Wiley Periodicals, Inc.Sci Ed88:493–534, 2004
The sky as a topic in science education
Authors: Galili Igal , Weizman Ayelet , Cohen Ariel 
Published: April 2004

AbstractThe concepts of sky and visibility distance, as perceived by different learners, are investigated for the first time as a subject of a science education research. Mental models of students with regard to the subject were elicited. They were interpreted in terms of two‐level hierarchy: schemes and facets‐of‐knowledge (defined in the paper). Our results suggest that many students do not consider sky to be a scientific (physical) concept. The majority perceives the sky as having an oblate profile. Among the parameters that determine this profile were mentioned daytime, atmosphere, geometry of the situation, and weather conditions. The students hold two major explanatory views (schemes) with regard to the sky: “the sky is the atmosphere” and “the sky is the appearance of space.” With regard to the visibility distance, the two following schemes prevail: “vision weakens with the distance” and “natural obstacles determine vision distance.” No significant correlation was found between the views regarding the sky appearance and the vision distance. Students do not relate Moon illusion to the profile of sky or visibility distance. The notions of sky and visibility distance are argued for inclusion into science curriculum, and implications of the findings to a constructivist instruction of the considered concepts and phenomena are discussed. © 2004 Wiley Periodicals, Inc. Sci Ed 88:574–593, 2004