bluuebunny/crossref_metadata_2025 huggingface dataset:
Rescue sedation with dexmedetomidine for diagnostic imaging: a preliminary report
Authors: NICHOLS DAVID P. , BERKENBOSCH JOHN W. , TOBIAS JOSEPH D.
Published: February 2005

Background : Sedation is frequently required during noninvasive radiological imaging in children. Although commonly used agents such as chloral hydrate and midazolam are generally effective, failures may occur. The authors report their experience with dexmedetomidine for rescue sedation during magnetic resonance imaging.

Methods : A retrospective chart review was undertaken.

Results : The cohort included five patients ranging in age from 11 months to 16 years. Following the failure of other agents (chloral hydrate and/or midazolam), dexmedetomidine was administered as a loading dose of 0.3–1.0 μg·kg−1·min−1 over 5–10 min followed by an infusion of 0.5–1.0 μg·kg−1·h−1. The dexmedetomidine loading dose required to induce sedation was 0.78 ± 0.42 μg·kg−1 (range 0.3–1.2). The maintenance infusion rate was 0.57 ± 0.06 μg·kg−1·h−1 (range 0.48–0.69). The imaging procedures were completed without difficulty. No patient required additional bolus administrations or changes in the infusion rate. The duration of the dexmedetomidine infusion ranged from 30 to 50 min. The mean decrease in heart rate was 13.6 ± 5.1 b·min−1 (14.3 ± 5.0% from baseline; P = 0.02), the mean decrease in systolic blood pressure was 26.4 ± 15.2 mmHg (24.6 ± 12.4% decrease from baseline; P = 0.004), and the mean decrease in respiratory rate was 1.4 ± 1.5 min−1 (7.5 ± 7.9% decrease from baseline; P = NS). PECO2 exceeded 6.5 kPa (50 mmHg) in one patient [maximum 6.6 kPa (51 mmHg)] with a maximum value of 6.0 ± 0.4 kPa (46 ± 3 mmHg). Oxygen saturation decreased from 98 ± 1 to 95 ± 1%; P = 0.001. No patient developed hypoxemia (oxygen saturation less than 90%). Mean time to recovery to baseline status was 112.5 ± 50.6 min and time to discharge was 173.8 ± 83.8 min.

Conclusions : Our preliminary experience suggests that dexmedetomidine may be an effective agent for procedural sedation during radiological imaging. Its potential application in this setting is discussed and other reports regarding its use in pediatric patients are reviewed.
Anesthesia for children with Wolf‐Hirshhorn syndrome: a report and literature review
Authors: MOHIUDDIN SHIREEN , MAYHEW JAMES F.
Published: February 2005

Wolf‐Hirshhorn is a rare chromosomal defect syndrome. We present two cases of children diagnosed with Wolf‐Hirshhorn syndrome, and discuss the ramifications of anesthesia for these patients.
S(+)‐ketamine for long‐term sedation in a child with retinoblastoma undergoing interstitial brachytherapy
Authors: KOZEK‐LANGENECKER SIBYLLE A. , MARHOFER PETER , SATOR‐KATZENSCHLAGER SABINE M. , DIECKMANN KARIN
Published: February 2005

We report the case of a 14‐month‐old child undergoing hourly pulse dose radiation therapy (interstitial brachytherapy) for 72 h in whom we employed S(+)‐ketamine for sedation during spontaneous breathing.
Anesthesia for pediatric renal transplantation with and without epidural analgesia – a review of 7 years experience
Authors: COUPE NICK , O'BRIEN MICHELLE , GIBSON PETER , DE LIMA JONATHAN
Published: February 2005

Background : Few objective data exist describing current anesthesia practice for pediatric renal transplantation. We describe here, the experience from an Australian tertiary pediatric center that has continued an active pediatric renal transplantation program after relocation in 1995. Areas of interest include preoperative status, fluid management, hemodynamic stability, perioperative complications, and the use of epidural analgesia. In particular, the influence of perioperative epidural analgesia on hemodynamic stability is addressed.

Methods : A retrospective review of anesthesia records of all patients undergoing pediatric renal transplantation performed at the Children's Hospital at Westmead (CHW), from November 1995 to October 2002 was carried out.

Results : Fifty‐three pediatric renal transplants were performed in 50 patients. Average age and weight were 10.2 years (range: 1–18 years) and 31.4 kg (range: 9–66 kg), respectively. A total of 14 recipients were less than or equal to 6 years of age. Twenty‐four children were recipients of cadaveric transplants, 29 children received kidneys from living related donors. Few children presented with severe anemia (two patients) gross electrolyte abnormalities (three patients) or uncontrolled hypertension. Intraoperatively, all children had central venous pressure monitoring and only four had invasive arterial blood pressure monitoring. Average intraoperative fluid administration was 88 ml·kg−1 (range: 30–190). Twenty‐three children received blood transfusions intraoperatively. Postoperative analgesia was provided using an epidural infusion in 39 patients and an opioid infusion/patient controlled analgesia in the remainder. There was a tendency to greater hemodynamic stability in the group, which received intra‐operative epidural analgesia. Half the patients who had epidural analgesia required parenteral opioid supplementation. Five patients had postoperative pulmonary edema. Minor postoperative adverse events included epidural associated motor block (three cases) and opioid related oversedation (one patient). No perioperative mortality or major morbidity was recorded.

Conclusions : Anesthesia for renal transplantation in pediatric patients at CHW is safe and effective using a selected range of drugs and techniques. Pretransplant medical optimization, careful preoperative assessment, adequate monitoring and precise fluid management together with appropriate postoperative analgesia typify the perioperative care of CHW renal transplant recipients.
Recombinant factor VIIa (NovoSeven®) as a hemostatic agent after surgery for congenital heart disease
Authors: RAZON YARON , EREZ ELDAD , VIDNE BERNARDO , BIRK EINAT , KATZ JACOB , TAMARI HANNA , DAGAN OVADIA
Published: February 2005

Background : Postoperative bleeding and blood product requirements can be substantial in children undergoing open‐heart surgery, and reexploration is required in 1% of cases. Recombinant activated factor VII (rFVIIa, NovoSeven®, NovoNordisk, Denmark) is a hemostatic agent approved for the treatment of hemophilic patients with inhibitors to factor VIII or factor IX. It has also been used with success in other conditions. We present our experience with rFVIIa treatment for uncontrolled bleeding after open‐heart surgery in five pediatric patients.

Methods : The study group consisted of five patients after open‐heart surgery with excessive blood loss. The patients were treated with rFVIIa after failure of conventional treatment to control the bleeding. Blood loss, blood product consumption, and coagulation test results were recorded before and after rFVIIa administration.

Results : In all cases, blood loss decreased considerably after rFVIIa administration (mean 7.8 ml·kg−1·h−1), almost eliminating the need for additional blood products, and the prolonged prothrombin time normalized. In two patients with thrombocytopathy, rFVIIa helped to discriminate surgical bleeding from bleeding caused by a defect in hemostasis. No side effects of rFVIIa treatment were noted.

Conclusions : These cases support the impression that RFVIIa is efficient and safe in correcting hemostasis in children after cardiopulmonary bypass when other means fail. However, the data are still limited, and more extensive research is needed.
Origins of Hippopotamidae (Mammalia, Cetartiodactyla): towards resolution
Authors: Boisserie Jean‐Renaud , Lihoreau Fabrice , Brunet Michel
Published: February 2005

The old debate on hippopotamid origins is still unresolved, balancing between two main phylogenetic hypotheses: origins within the Anthracotheriidae vs. origins within the Tayassuidae. The characters used in the literature to support one, the other, or both hypotheses were re‐examined in light of a better known primitive hippopotamid morphology. A cladistic analysis was performed on the basis of these characters. On the one hand, although many features similar in hippopotamuses and anthracotheres appear to have evolved in parallel, the family Anthracotheriidae remains the best putative hippopotamus stem group on the basis of the reviewed characters. However, the precise identification of a stem group within this family is still uncertain. On the other hand, the lineage proposed in the tayassuid hypothesis should not be retained, being mostly based on some incorrect observations and without taking into account the derived or primitive nature of the features. The anatomic similarities seen between modern peccaries and Hippopotamus amphibius are the results of convergences between advanced species of both families.
International community health networking project: two year follow‐up of graduates
Authors: Duffy M. E. , Farmer S. , Ravert P. , Huittinen L.
Published: February 2005

Aim:  This paper presents the perceptions of graduates 2 years post‐exchange in a USA–European Union funded programme. The primary goal of this 8‐week exchange programme was to increase cultural knowledge and sensitivity by teaching a common module of community health assessment and planning to multi‐national groups of undergraduate students in four countries.

Background:  Cultural diversity and globalization are among the factors that encourage faculty in nursing to develop programmes of international exchange for students. The challenge is to combine the exchange with the teaching of other courses required by the home institution during the same semester.

Methods:  Twenty‐one graduates of participating USA schools responded to an open‐ended interview by telephone or email 2 years after graduation. Bennett's continuum (1993) of intercultural sensitivity was used to assess cultural development.

Findings:  Graduates overwhelmingly supported international education and described its continued impact personally and professionally. Gains in cultural sensitivity were perceived as the greatest benefit and influence on their practice. The majority of graduates were believed to be in Bennett's ethnorelative categories of acceptance and adaptation. The depth and breadth of previous cultural experiences, specific host and home schools, and previous travel were found to be related to development on the intercultural sensitivity continuum.

Discussion:  Most important are the findings from this evaluation that provide insight into the factors enhancing growth of intercultural sensitivity. Previous travel, characteristics of the home and host institutions, and the opportunity and willingness to be a cultural outsider were important influences.
Nursing and public health in Europe – a new continuous education programme
Authors: Danielson E. , Krogerus‐Therman I. , Sivertsen B. , Sourtzi P.
Published: February 2005

The aim of this paper is to describe the development of a new education programme in public health for nurses in the European Union (EU). The project, ‘Development of a Continuous Professional Education Programme for Nurses in Public Health’, is described together with its background and aim, which is to contribute to the development of new competencies of nurses in nursing and public health. For the development of these competencies, the framework for the programme's guidelines is organized around core modules common for all EU countries and elective modules, based on national health needs and policies proposed by each country. An example of the implementation of the programme from Sweden, where the programme has already been offered, is also presented. In addition to the educational programme itself, the opportunities for networking for nurses and teachers from different countries resulting from this effort are discussed. Finally, the evolving nature of public health in nursing is presented in relation to the roles that nurses/midwives already perform in various countries and situations, in order to point out the potential of this programme's contribution to the promotion of health of all European citizens.
Patterns of community relationship: nurses, non‐governmental organizations and internally displaced persons
Authors: Solheim K.
Published: February 2005

Background: Internally displaced persons (IDPs) are one of the largest at‐risk populations in the world. Nurses provide health services to IDPs as staff of non‐governmental organizations (NGO). IDPs are also employed to deliver NGO services. The way that NGOs and field staff (nurses and others) interact with employed IDPs can enhance or diminish IDP quality of life.

Aim: This report describes patterns of relationships in a community formed by an American NGO, its field staff and IDPs as they worked together in a refugee camp at the Thai‐Cambodian border over 13 years.

Methods: This qualitative case study describes relational patterns from the NGO perspective. Content analysis was used to process data from in‐depth interviews with organizational leaders (n = 4) and organizational documents (n = 234).

Findings: A health care training and service mission, carried out between an NGO, its field staff and IDPs, was based on a philosophy that turned programme activity and authority over to IDP staff. Over 400 IDPs, assisted by 235 field staff, delivered effective health care to 85 000 people over 13 years.

Conclusions: Work‐centred relationships between NGOs, field staff and IDPs are significant; they can be consciously created to promote effective, autonomous IDP management of health care.
Conflict Management for Effective Top Management Teams and Innovation in China*
Authors: Chen Guoquan , Liu Chunhong , Tjosvold Dean
Published: February 2005

abstract  Top management teams may be critical for developing organizations that can keep abreast of marketplace changes and innovate. Several streams of strategy research have argued that conflict and diversity promote top management team effectiveness. This study proposes that how top management teams manage conflict can greatly contribute to their effective leadership of organizational innovation. A total of 378 executives from 105 organizations in China completed measures of conflict management (cooperative, competitive, and avoiding) and productive conflict (an outcome of conflict). Separately, 105 CEOs from these firms indicated their team's effectiveness and their organization's innovativeness. Results support the theory that conflict management can contribute to making top management teams effective. Structural equation analysis suggests that cooperative conflict management promotes productive conflict and top management team effectiveness that in turn result in organizational innovation. These results, coupled with previous research, were interpreted as suggesting that cooperative conflict management is an important contributor to effective top management teams even in the collectivist culture of China.
An Examination of Differences Between Organizational Legitimacy and Organizational Reputation*
Authors: Deephouse David L. , Carter Suzanne M.
Published: February 2005

abstract  Organizational legitimacy and organizational reputation have similar antecedents, social construction processes and consequences. Nonetheless, an improved understanding of relationships between legitimacy and reputation requires that differences between the two be specified and clarified. Our examination of past research indicates that legitimacy emphasizes the social acceptance resulting from adherence to social norms and expectations whereas reputation emphasizes comparisons among organizations. We empirically examine two antecedents of the financial, regulatory, and public dimensions of legitimacy and reputation in a population of US commercial banks. We find that isomorphism improves legitimacy, but its effects on reputation depend on the bank's reputation. Moreover, higher financial performance increases reputation, but does not increase the legitimacy of high performing banks.
Learning to Build a Car: An Empirical Investigation of Organizational Learning
Authors: Dyck Bruno , Starke Frederick A. , Mischke Gary A. , Mauws Michael
Published: February 2005

abstract This study provides a longitudinal empirical examination of the basic elements ofNonaka's (1994) dynamic theory of organizational knowledge creation. First, the data illustrate the notion that knowledge creation in organizations proceeds through an intertwined four‐phase process: (1)socialization(tacit knowledge amplification); (2)externalization(tacit knowledge is transformed into explicit knowledge); (3)combination(explicit knowledge amplification); and (4)internalization(explicit knowledge is transformed into tacit knowledge). Second, the study extends Nonaka's theory by comparing the relative amount of intra‐organizational knowledge transfer occurring during periods of product redesign with the amount of knowledge transfer occurring during steady‐state periods. Thequestionnairedata suggest that the overall level of knowledge transfer is higher during periods of product redesign than it is during the steady state, whereas theinterviewdata indicate that there were more mentions of knowledge transfer during the steady state. Third, the data suggest that there may be benefit in addingtacit error correctionas a fifth phase in the learning cycle. This phase is characterized by a dual emphasis on externalization and internalization. Implications of these findings are discussed.
An Empirical Test of Cognitive Style and Strategic Decision Outcomes*
Authors: Hough Jill R. , Ogilvie Dt
Published: February 2005

abstract We examine how cognitive style, as measured by the MBTI, affects strategic decision outcomes. Executives participated in a simulated strategic decision making environment that allowed controlled collection of decision outcomes, including manager decisiveness, decision quality, and perceived effectiveness. We found that iNtuiting/Thinking managers used their intuition to make cognitive leaps based on objective information to craft more decisions of higher quality than other managers. In contrast, Sensing/Feeling types used time to seek socially acceptable decisions, which led to the lowest number of decisions and the lowest perceived effectiveness of all. We found no effect on decisiveness or perceived effectiveness based on a manager's preference for Perceiving or Judging. However, we found that others perceived Extraverted managers as being more effective than Introverted managers when, in fact, the Extraverts were no more decisive than Introverts. Thus, cognitive style influences actual decision outcomes as well as how others perceive one's decision performance.
Anterior localization of maternal mRNAs in a short germ insect lacking bicoid
Authors: Bucher Gregor , Farzana Laila , Brown Susan J. , Klingler Martin
Published: February 2005

Summary
Anterior morphogens have long been postulated to function in early pattern formation in several insect taxa. Genetic studies in Drosophila revealed that the Bicoid protein performs as such in the fly. Maternally provided bicoid (bcd) mRNA is localized at the anterior pole of the oocyte and, upon fertilization, acts as the source of a morphogenetic gradient of Bicoid protein. Despite its central role in Drosophila, it is believed that bicoid arose rather recently during dipteran evolution through duplication of the Hox3 ortholog zen.

Here we show that in the red flour beetle Tribolium castaneum, RNAs of the homologs of the Drosophila transcription factors eagle (Tc′eagle) and pangolin (Tc′pan) are maternally localized at the anterior pole of the egg. It is possible that underlying mechanisms for the anterior localization of maternal RNAs evolved independently in the two clades. However, considering the complexity of the process in Drosophila, it is more tempting to speculate that the molecular machinery evolved only once during insect evolution. Under this assumption, it was present before bicoid evolved as an anterior morphogen. To become concentrated at the anterior pole of the egg bicoid may only have had to acquire a signal sequence that was recognized by the preexisting localization machinery. Although we were not able to demonstrate a function in early embryogenesis for Tc′eagle or Tc′pan, our findings suggest that other factors likely function as anterior determinants in Tribolium, and other nondipteran insects.
Muscle Fiber Regeneration in Human Permanent Lower Motoneuron Denervation: Relevance to Safety and Effectiveness of FES‐Training, Which Induces Muscle Recovery in SCI Subjects
Authors: Carraro Ugo , Rossini Katia , Mayr Winfried , Kern Helmut
Published: February 2005

Abstract:  Morphologic characteristics of the long‐term denervated muscle in animals suggest that some original fibers are lost and some of those seen are the result of repeated cycles of fiber regeneration. Muscle biopsies from lower motoneuron denervated patients enrolled in the EU Project RISE show the characteristics of long‐term denervation. They present a few atrophic or severely atrophic myofibers dispersed among adipocytes and connective tissue (denervated degenerated muscle, DDM). Monoclonal antibody for embryonic myosin shows that regenerative events are present from 1‐ to 37‐years postspinal cord injury (SCI). After 2‐ to 10‐years FES‐training the muscle cryosections present mainly large round myofibers. In the FES‐trained muscles the regenerative events are present, but at a lower rate than long‐term denervated muscles (myofiber per mm2 of cryosection area: 0.8 ± 1.3 in FES vs. 2.3 ± 2.3 in DDM, mean ± SD, P = 0.011). In our opinion this is a sound additional evidence of effectiveness of the Kern's electrical stimulation protocol for FES of DDM. In any case, the overall results demonstrate that the FES‐training is safe: at least it does not induce more myofiber damage/regeneration than denervation per se.
Evaluation of FES‐Induced Knee Joint Moments in Paraplegics with Denervated Muscles
Authors: Gallasch Eugen , Rafolt Dietmar , Kinz Gudrun , Fend Martin , Kern Helmut , Mayr Winfried
Published: February 2005

Abstract:  The pendulum test was applied to evaluate functional electrical stimulation (FES)‐induced joint moments in paraplegics with denervated muscles. Therefore a manipulandum was connected to the knee joint and programmed to elicit gravity‐induced leg oscillations. The FES‐induced output torque was compensated for in order to keep the leg in a mean vertical position (knee angle 90°). A second‐order dynamical model was applied to extract the elastic and viscous moments from the recorded leg oscillations. This model provided an almost adequate description of the relaxed and FES‐contracted states. In the relaxed state the elastic moment was 15.3 ± 2.37 Nm/rad and the viscous moment was 0.41 ± 0.21 Nms/rad. The FES‐induced elastic moment was 29.4 ± 28.5 Nm/rad and the FES‐induced viscous moment was 1.53 ± 1.03 Nms/rad (N = 10,   before   FES‐training).
Stimulation Parameter Optimization for FES Supported Standing up and Walking in SCI Patients
Authors: Bijak Manfred , Rakos Monika , Hofer Christian , Mayr Winfried , Strohhofer Maria , Raschka Doris , Kern Helmut
Published: February 2005

Abstract:  Functional Electrical Stimulation (FES) to restore leg movement for standing up and walking (stepping) in SCI patients with intact lower motor neuron is used by several groups. Usually quadriceps muscles are stimulated for hip and knee extension, gluteus muscles for hip stabilization, and the common peroneal nerve to elicit the flexion reflex. The requirement to get a natural movement would need a huge number of stimulation channels— a request that could be easily fulfillled from the engineer's point of view but not from the point of practicability since each stimulated muscle requires two skin‐attached electrodes resulting in a prolonged time for donning and doffing. In the described project a newly developed eight channel stimulator that can vary the stimulation parameters in many ways and over a wide range is used. The goal is to achieve a natural movement with a minimum of surface electrodes by optimizing the stimulation parameters. Seven experienced FES users and five unexperienced persons (all between Th4‐Th11) participate in this study. Standing up can be significantly improved by optimizing the time delay between the onset of quadriceps and gluteus muscles (0.2–0.4 s) and the duration of the ramp. A 0.2 s delay gives good results in heavy patients while slower ramps (0.4 s) are required in slim patients. During stepping, gluteus muscle timing is not very crucial. Gluteus stimulation is turned off 0.1–0.2 s before quadriceps muscle and with the same delay turned on again. Of major influence on the gait quality is the timing during heel strike when peroneal stimulation is switched off and quadriceps stimulation is turned on. Six patients require 0.0–0.1 s where neither peroneal nor quadriceps stimulation is applied, the others require an overlap of 0.1–0.2 s. Activation of adductor muscles during standing up and during the swing phase helps to avoid hip abduction and improves knee trajectories.
Repetitive Painful Stimulation Produces an Expansion of Withdrawal Reflex Receptive Fields in Humans
Authors: Spaich Erika G. , Arendt‐Nielsen Lars , Andersen Ole K.
Published: February 2005

Abstract:  The aims of the present study were to investigate whether temporal summation of the nociceptive withdrawal reflex depends on the stimulation site on the sole of the human foot, and to characterize the reflex receptive fields (RRF) of lower limb muscles to repetitive stimulation. The cutaneous RRFs were assessed in 15 subjects in sitting position by recording the EMG from five lower leg muscles and the kinematic responses (ankle, knee, and hip joints) to repetitive painful electrical stimulation. The stimulus consisted of a series of five stimuli (frequency: 3 Hz) delivered randomly at 10 different sites on the sole of the foot. The size of the reflexes increased generally between the first and the second stimulus, however, the increment depended on the stimulation site. In tibialis anterior, the RRF covered the distal sole of the foot and gradually expanded during the stimulus train. No expansion toward the heel area was detected. In soleus, the reflexes were facilitated after the second stimulus at all sites and remained in this state until the last stimulus. In vastus lateralis, biceps femoris, and iliopsoas a gradual expansion of the RRF was seen, resulting in RRFs covering the lateral, distal foot, and part of the proximal foot (iliopsoas). Knee and hip flexion were evoked at all sites. Ankle dorsiflexion was evoked at the distal foot, while ankle plantarflexion was evoked at the heel. The enlargement of the RRF reflects spinal temporal summation leading to gradually stronger reflex responses. The degree of temporal summation was dependent on stimulation site. The facilitation of the withdrawal reflex responses due to repetitive stimulation might have potential applications in the rehabilitation engineering field, where these reflexes could be used to assist gait of patients with central nervous system injuries.
Spastic Bladder and Spinal Cord Injury: Seventeen Years of Experience with Sacral Deafferentation and Implantation of an Anterior Root Stimulator
Authors: Kutzenberger Johannes , Domurath Burkhard , Sauerwein Dieter
Published: February 2005

Abstract:  Introduction: Spinal cord injured patients with a suprasacral lesion usually develop a spastic bladder. The hyperreflexia of the detrusor and the external sphincter causes incontinence and threatens those patients with recurrent urinary tract infections (UTI), renal failure, and autonomic dysreflexia. All of these severe disturbances may be well managed by sacral deafferentation (SDAF) and implantation of an anterior root stimulator. Material and Method: Between September 1986 to December 2002, 464 paraplegic patients (220 female, 244 male) received a SDAF‐SARS. Almost exclusively the SDAF was done intradurally, which means with one operation field there can be done two steps (SDAF and SARS). Results: 440 patients have a follow‐up with 6.6 years (at least > 6 months−17 years). The complete deafferentation was successful in 94.1%. A total of 420 paraplegics may use the SARS for voiding (frequency 4.7 per day) and 401 use it for defecation (frequency 4.9 per week). Continence was achieved in 364 patients (83%). UTI declined from 6.3 per year preoperatively to 1.2 per year postoperatively. Kidney function presented stable. Early complications were 6 CSF leaks, 5 implant infections. Late complications with receiver or cable failures made us do surgical repairs in 34 paraplegics. A step‐by‐step program for trouble‐shooting differentiates implant failure and myogenic or neurogenic failure. Conclusion: SDAF is able to restore the reservoir function of the urinary bladder and to achieve continence. Autonomic dysreflexia disappeared in most of the cases. By means of an accurate adjustment of stimulation parameters it is possible to accomplish low resistance micturition. The microsurgical technique requires an intensive education. One has to be able to manage late implant complications.
Intraoperative Recording of Sacral Root Nerve Signals in Humans
Authors: Kurstjens Mathijs , Rijkhoff Nico J.M. , Borau Albert , Rodríguez Alfred , Vidal Joan , Sinkjær Thomas
Published: February 2005

Abstract:  Electroneurographic signals were intraoperatively recorded from the S3 sacral nerve root in two SCI patients. The aim of this study was to record afferent nerve signals in response to mechanical stimulation of the urinary bladder, rectum, and dermatome. Such signals could be used in an implantable neuroprosthesis to treat neurogenic detrusor overactivity. In both patients a neural response was recorded from the dermatome and the rectum, but from the bladder only in one patient. The results were consistent with results from animal and other human studies. Further studies are however, needed because the number of  subjects investigated  remains  low.
Numerical Investigation of the Effects of the Clearance Gap Between the Inducer and Impeller of an Axial Blood Pump
Authors: Chan Weng‐Kong , Wong Yew‐Wah , Ong Wendy , Koh Sy‐Yuan , Chong Victor
Published: February 2005

Abstract:  A series of numerical models are generated to investigate the flow characteristics and performance of an axial blood pump. The pump model includes a straightener, an inducer–impeller, and diffuser. Numerical studies of the effects of angular alignment of the inducer and impeller blades and the axial clearance gap between the inducer and impeller are presented in this article. The pump characteristics derived from numerical simulation are validated with experimental data. Numerically simulated results showed a sinusoidal variation in the pressure generated across the pump with changes in angular alignment between the inducer and impeller. This is attributed to additional losses when flow is forced or diverted from the trailing edge of the inducer to either the pressure or suction side of the impeller blade when the alignment between the two sets of blades is not optimal. The pressure generated is a maximum when the impeller blades are at 0 or 30 degrees with respect to the inducer. The effect of rotating the impeller with respect to the inducer causes the sinusoidal pressure variation. In addition, it was observed that when the clearance gap between the inducer and impeller is reduced to 1 mm, the pressure generated is a minimum when compared to the other models. This is attributed to the interference between the inducer and impeller when the gap separating them is too small. The location of the maximum pressure on the pressure side of the impeller blade shifts upstream while its magnitude decreases for small clearance gap between the inducer and the impeller. There was no flow separation in the inducer while small regions of backflow are observed at the impeller trailing edge. Recommendations for future modifications and improvements to the pump design and model simulation are also given.
Melatonin generates singlet oxygen on laser irradiation but acts as a quencher when irradiated by lamp photolysis
Authors: Maharaj D. S. , Molell H. , Antunes E. M. , Maharaj H. , Maree D. M. , Nyokong T. , Glass B. D. , Daya S.
Published: February 2005

Abstract:  Melatonin, a naturally occurring chemical mediator, although assigned a diverse range of functions, has attracted interest in recent years because of its ability to function as a free radical scavenger. Because of the implications of singlet oxygen in neurotoxicity, the objective of the study was to investigate the ability of melatonin to quench singlet oxygen generated using laser irradiation or lamp photolysis. The results show that melatonin produces radicals upon laser irradation while the lamp photolysis studies show that melatonin is able to scavenge singlet oxygen produced by naphthalene. While melatonin is a free radical scavenger under biological conditions, it acts as a generator of singlet oxygen and or radicals (as ΦΔ is 1.41) when irradiated with laser light, implying that it has the potential to be used in photodynamic therapy in the destruction of tumors.
Melatonin regulates circadian electroretinogram rhythms in a dose‐ and time‐dependent fashion
Authors: Peters Jennifer L. , Cassone Vincent M.
Published: February 2005

Abstract:   The circadian rhythm of the chick electroretinogram (ERG) is regulated by the indoleamine hormone melatonin. To determine if the concentration of melatonin or the time at which it was administered would have differential effects on ERG parameters, we conducted experiments analyzing the effects of melatonin at different times of the day. Circadian rhythms of a‐ and b‐wave implicit times and amplitudes were observed in both light:dark (LD) and in continuous darkness (DD). Intramuscular melatonin administration of 1 mg/kg and 100 ng/kg decreased a‐ and b‐wave amplitudes and increased a‐ and b‐wave implicit times. This effect was significantly greater than that observed for 1 ng/kg melatonin, which had little to no effect over the saline controls. The effect of 1 mg/kg and 100 ng/kg melatonin on a‐ and b‐wave amplitude in LD and on b‐wave amplitude in DD was greater during the night (ZT/CT 17) than during the day (ZT/CT 5). The fold change in b‐wave implicit time over that of controls was greater during the day (ZT/CT 5) than during the night (ZT/CT 17). These data indicate that melatonin may play a role in regulating a day and night functional shift in the retina, and that it does so via regulation of a retinal clock.
The human pineal gland and melatonin in aging and Alzheimer's disease
Authors: Wu Ying‐Hui , Swaab Dick F.
Published: February 2005

Abstract:  The pineal gland is a central structure in the circadian system which produces melatonin under the control of the central clock, the suprachiasmatic nucleus (SCN). The SCN and the output of the pineal gland, i.e. melatonin, are synchronized to the 24‐hr day by environmental light, received by the retina and transmitted to the SCN via the retinohypothalamic tract. Melatonin not only plays an important role in the regulation of circadian rhythms, but also acts as antioxidant and neuroprotector that may be of importance in aging and Alzheimer's disease (AD). Circadian disorders, such as sleep–wake cycle disturbances, are associated with aging, and even more pronounced in AD. Many studies have reported disrupted melatonin production and rhythms in aging and in AD that, as we showed, are taking place as early as in the very first preclinical AD stages (neuropathological Braak stage I–II). Degeneration of the retina‐SCN‐pineal axis may underlie these changes. Our recent studies indicate that a dysfunction of the sympathetic regulation of pineal melatonin synthesis by the SCN is responsible for melatonin changes during the early AD stages. Reactivation of the circadian system (retina‐SCN‐pineal pathway) by means of light therapy and melatonin supplementation, to restore the circadian rhythm and to relieve the clinical circadian disturbances, has shown promising positive results.
Fatigue Crack Growth Thresholds of Deflected Mixed-Mode Cracks in PWA1484
Authors: Chan K. S. , Feiger J. , Lee Y.-D. , John R. , Hudak, S. J.
Published: February 2005

The fatigue crack growth (FCG) behavior of PWA1484 single crystals was characterized in air under mixed-mode loading at 593°C as a function of crystallographic orientation using an asymmetric four-point bend test technique. Most mixed-mode fatigue cracks deflected from the symmetry plane and propagated as transprecipitate, noncrystallographic cracks, while self-similar fatigue crack growth occurred on the (111) planes in (111)/[011] and 111/[112]¯ oriented crystals. The local stress intensity factors and the crack paths of the deflected mixed-mode cracks were analyzed using the finite-element fracture mechanics code, FRANC2D/L. The results indicated that the deflected crack path was close to being normal to the maximum tensile stress direction where the Mode II component diminishes. Crystallographic analysis of the deflected crack paths revealed that the Mode I and the deflected mixed-mode cracks were usually of different crystallographic orientations and could exhibit different Mode I FCG thresholds when the crystallography of the crack paths differed substantially. These results were used to identify the driving force and conditions for cracking mode transition.
Contact Damage of Dental Multilayers: Viscous Deformation and Fatigue Mechanisms
Authors: Huang M. , Niu X. , Shrotriya P. , Thompson V. , Rekow D. , Soboyejo W. O.
Published: February 2005

This paper presents the results of recent experimental and finite element studies of contact damage in model dental multilayered systems with equivalent elastic properties to those of crown/join/dentin layers that are found in dental restorations. Subsurface radial cracks are observed to form after Hertzian indentation fatigue loading. In order to explain the possible failure mechanisms, the viscous deformation of the foundation (dentinlike ceramic filled polymer) and epoxy join layers are measured. Finite element and analytical models are then developed in an effort to explain the observed contact-induced deformation of the composite multilayered system. Our results suggest that: viscous deformation of the join and foundation layers can give rise to increased tensile stresses in the top elastic layers (glass or zirconia); defects at the bottom of the top layers (induced by grinding steps before crown attachment) are also shown to promote ratcheting phenomena that can lead to stress build-up in the top layers; and viscous flow of the cement can cause the subcritical crack growth in the dental ceramics.
Modeling of Creep Behavior of a Rotating Disc in the Presence of Both Composition and Thermal Gradients
Authors: Gupta V. K. , Singh S. B. , Chandrawat H. N. , Ray S.
Published: February 2005

The creep behavior of a rotating disc made of isotropic composite containing varying amounts of silicon carbide in the radial direction has been investigated in the presence of a thermal gradient, also in the radial direction. The variation of silicon carbide content has been so tailored as to contain larger amounts of particles in a highly stressed region. This type of inhomogeneous material is known as Functionally Graded Material (FGM). The thermal gradient experienced by the disc is the result of braking action as estimated by FEM analysis. The creep behavior of the disc under stresses developing due to rotation has been determined following Sherby’s law and compared with that of a similar disc following Norton’s law. The difference in the distribution of stresses and strain rates in the discs does not follow any definite trend but the values are somewhat different. The presence of thermal gradient and a linear particle gradient separately or their simultaneous presence result in a significant decrease in steady state creep rates as compared to that in a composite disc with the same average particle content (20 vol %) distributed uniformly and operating under isothermal condition. Further, the study revealed that the creep behavior of a FGM disc could be significantly improved by increasing the gradient of particle distribution while keeping the same average particle content of 20 vol % silicon carbide in the disc.
A Study of Creep in Polysilicon MEMS Devices
Authors: Tuck K. , Jungen A. , Geisberger A. , Ellis M. , Skidmore G.
Published: February 2005

Plastic deformation of polysilicon at high temperatures under stress due to creep has been demonstrated at the micro scale. This type of material behavior is generally associated with mechanical failure, however it can also be used to permanently deform or position a device. In order for creep in polysilicon to be used for MEMS applications its mechanical properties must be investigated. In this work, an experimental micro test structure is developed and measurements of high temperature plastic deformation within polysilicon are conducted. Both increases in temperature and stress are shown to increase the creep rate within the studied beams in the region of interest of the test device. Immediate plastic deformation of polysilicon has been observed to start at approximately 63% of the absolute melting temperature under moderate stress.
High Strain-Rate, Small Strain Response of a NiTi Shape-Memory Alloy
Authors: Nemat-Nasser Sia , Yong Choi Jeom , Guo Wei-Guo , Isaacs Jon B. , Taya Minoru
Published: February 2005

The compressive response of a NiTi shape-memory alloy is investigated at various strain rates using UCSD’s modified 12-in. Hopkinson pressure bar and a conventional Instron machine. To obtain a constant strain rate during the formation of a stress-induced martensite in a Hopkinson test, a copper tube of suitable dimensions is employed as a pulse shaper, since without a pulse shaper the strain rate of the sample varies significantly as its microstructure changes from austenite to martensite, whereas with proper pulse shaping techniques a nearly constant strain rate can be achieved over a certain deformation range. The NiTi shape-memory alloy shows a superelastic response for small strains at all considered strain rates and at room temperature, 296 K. At this temperature and below a certain strain rate, the stress–strain curves of the NiTi shape-memory alloy display two regimes: an elastic austenite regime and a transition (stress-induced martensite) regime. The transition stress of this material and the work-hardening rate in the stress-induced martensite regime increase with increasing strain rate, the latter reaching a steady state level and then rapidly increasing.
Strength of clean indoor air laws and smoking related outcomes in the USA
Authors: McMullen K M , Brownson R C , Luke D , Chriqui J
Published: February 2005

Objectives:Environmental tobacco smoke (ETS) is often encountered in the workplace. There have been efforts to apply and enforce state laws limiting workplace smoking. There has been little study of the relative effectiveness of state and/or local laws in affecting both rates of workplace ETS exposure and adult smoking rates. This study investigates these hypotheses, as well as the effect of these laws on youth smoking.

Design:This is a secondary data analysis using sources including the Current Population Survey (CPS), Behavioral Risk Factor Surveillance System (BRFSS), Youth Risk Behavior Survey (YRBS), and the National Household Survey of Drug Abuse (NHSDA) between the years of 1996 and 1999. Linear regression models were used to investigate the effect of a state’s clean indoor air (CIA) law (using a measure of extensiveness) on the overall amount of people who reported working in a smoke-free environment, youth smoking rates and adult smoking rates.

Results:The extensiveness of a state’s CIA law was found to be a reliable predictor of the percentage of indoor workers who report a smoke-free work environment and the rates of youth smoking. State CIA laws were not conclusively associated with adult smoking rates.

Conclusions:The extensiveness of a state’s CIA law is strongly associated with a higher percentage of indoor workers reporting a smoke-free work environment. This study did not reveal a similar association between local laws and smoke-free work environments. Youth smoking rates, shown to be related to state CIA laws, may be further affected with more stringent CIA policy.
GAUGE TRANSFORMATIONS, BRST COHOMOLOGY AND WIGNER'S LITTLE GROUP
Authors: MALIK R. P.
Published: February 2005

We discuss the (dual-)gauge transformations and BRST cohomology for the two (1+1)-dimensional (2D) free Abelian one-form and four (3+1)-dimensional (4D) free Abelian two-form gauge theories by exploiting the (co-)BRST symmetries (and their corresponding generators) for the Lagrangian densities of these theories. For the 4D free two-form gauge theory, we show that the changes on the antisymmetric polarization tensor eμν(k) due to (i) the (dual-)gauge transformations corresponding to the internal symmetry group, and (ii) the translation subgroup T(2) of the Wigner's little group, are connected with each other for the specific relationships among the parameters of these transformation groups. In the language of BRST cohomology defined with respect to the conserved and nilpotent (co-)BRST charges, the (dual-)gauge transformed states turn out to be the sum of the original state and the (co-)BRST exact states. We comment on (i) the quasitopological nature of the 4D free two-form gauge theory from the degrees of freedom count on eμν(k), and (ii) the Wigner's little group and the BRST cohomology for the 2D one-form gauge theory vis-à-vis our analysis for the 4D two-form gauge theory.
I=2 PION SCATTERING LENGTH WITH IMPROVED ACTIONS ON ANISOTROPIC LATTICES
Authors: DU XINING , MENG GUANGWEI , MIAO CHUAN , LIU CHUAN
Published: February 2005

ππ scattering length in the I=2 channel is calculated within quenched approximation using improved gauge and improved Wilson fermion actions on anisotropic lattices. The results are extrapolated towards the chiral, infinite volume and continuum limit. This result improves our previous result on the scattering length. In the chiral, infinite volume and continuum limit, we obtain [Formula: see text], which is consistent with the result from Chiral Perturbation Theory, the experiment and results from other lattice calculations.
CLASSICAL AND QUANTUM TIME DEPENDENT SOLUTIONS IN STRING THEORY
Authors: MARTÍNEZ-PRIETO C. , OBREGÓN O. , SOCORRO J.
Published: February 2005

Using the ontological interpretation of quantum mechanics in a particular sense, we obtain the classical behavior of the scale factor and two scalar fields, derived from a string effective action for the Friedmann–Robertson–Walker (FRW) time dependent model. Besides, the Wheeler–DeWitt equation is solved exactly. We speculate that the same procedure could also be applied to S-branes.
FIELD THEORETIC REALIZATIONS FOR CUBIC SUPERSYMMETRY
Authors: MOHAMMEDI N. , MOULTAKA G. , DE TRAUBENBERG M. RAUSCH
Published: February 2005

We consider a four-dimensional space–time symmetry which is a nontrivial extension of the Poincaré algebra, different from supersymmetry and not contradicting a priori the well-known no-go theorems. We investigate some field theoretical aspects of this new symmetry and construct invariant actions for noninteracting fermion and noninteracting boson multiplets. In the case of the bosonic multiplet, where two-form fields appear naturally, we find that this symmetry is compatible with a local U(1) gauge symmetry, only when the latter is gauge fixed by a 't Hooft–Feynman term.