bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimisation of GaN overgrowth of InAlN for DBRs
Authors: Sadler Thomas C. , Kappers Menno J. , Oliver Rachel A.
Published: January 2009

The growth of InAlN lattice matched to GaN is a recent development with a major application in nitride distributed Bragg reflectors (DBRs). In this work we investigate three ways of capping lattice matched InAlN layers to make the GaN layers in a DBR, while ensuring that InAlN is not damaged in the process and that the top GaN surface is suitable for further growth. Growing the GaN caps in a nitrogen atmosphere at the same temperature as the InAlN does not observably affect the InAlN epilayer but the cap has a top surface with large undulations unsuitable for DBRs. Growing the GaN at 1000 °C in a hydrogen atmosphere results in good GaN surfaces without altering the bulk of the InAlN epilayer but does alter the InAlN surface, possibly by causing the desorption of In. The advantages of both methods can be combined by growing the first 10 nm of the cap at the same temperature as the InAlN and the rest at 1000 °C. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Large area GaN and AlN template substrates fabricated by HVPE
Authors: Soukhoveev Vitali , Volkova Anna , Ivantsov Vladimir , Kovalenkov Oleg , Syrkin Alexander , Usikov Alexander
Published: January 2009

Hydride vapour phase epitaxy (HVPE) is known as fast deposition method to produce both free‐standing GaN substrate materials and thick low‐defect GaN on 2‐inch sapphire and AlN layers on 2‐inch sapphire and conductive silicon carbide (SiC) substrates. These substrate materials of 2‐inch size are available as commercial product. In this paper, we extend the HVPE abilities to new fields including up to 23 μm thick crack‐free AlN layers growth on 3‐inch and 100‐mm SiC substrates (AlN/SiC template substrates) and up to 125 μm thick GaN layers grown on 3‐inch sapphire (GaN/sapphire template substrates). For 21‐23 μm thick AlN layers grown on 100‐mm SiC substrates, the X‐ray rocking curve FWHM was ranged from 200 to 300 arc sec and from 600 to 800 arc sec for the (00.2) and the (10.2) AlN reflections, respectively. For 115‐125 μm thick GaN layers, the X‐ray FWHM values were 120‐150 arcsec and 200‐230arc sec for the (00.2) and the (10.2) GaN reflections, respectively, that corresponds screw dislocation density of (3‐5)×107 cm–2 evaluated based on XRD data. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Image‐based path planning for outdoor mobile robots
Authors: Huang Wesley H. , Ollis Mark , Happold Michael , Stancil Brian A.
Published: January 2009

Mobile robots operating in natural terrain need some sort of long‐range perception in order to navigate efficiently. Whereas LADAR is a commonly used sensor on such systems, providing range data out to 25 m and beyond, we have instead focused on what information can be extracted from vision. Our robot has only two stereo camera pairs for terrain sensing; they provide reliable stereo data up to 5 m away, but this is not enough to prevent myopic behavior. To overcome this problem, we have developed a novel approach to navigation using monocular imagery by planning a path in the image space. We take a monocular image and apply a learned color‐to‐cost mapping to transform the raw image into a cost image. Then, after a pseudo‐configuration‐space transform, we search for a pixel‐to‐pixel path from a point in front of the robot to the projected goal point in the cost image. Our implementation has been shown to react to obstacles at a range of 93 m, far beyond the range of our stereo perception. We describe the details of our method and results from testing under the DARPA Learning Applied to Ground Robots (LAGR) program and discuss the characteristics and trade‐offs of our approach. © 2009 Wiley Periodicals, Inc.
Learning terrain segmentation with classifier ensembles for autonomous robot navigation in unstructured environments
Authors: Procopio Michael J. , Mulligan Jane , Grudic Greg
Published: January 2009

Autonomous robot navigation in unstructured outdoor environments is a challenging area of active research and is currently unsolved. The navigation task requires identifying safe, traversable paths that allow the robot to progress toward a goal while avoiding obstacles. Stereo is an effective tool in the near field, but used alone leads to a common failure mode in autonomous navigation in which suboptimal trajectories are followed due tonearsightedness, or the robot's inability to distinguish obstacles and safe terrain in the far field. This can be addressed through the use of machine learning methods to accomplishnear‐to‐farlearning, in which near‐field terrain appearance and stereo readings are used to train models able to predict far‐field terrain. This paper proposes to enhance existing,memorylessnear‐to‐far learning approaches through the use ofclassifier ensemblesthat allow terrain models trained on data seen at different points in time to be preserved and referenced later. These stored models serve as memory, and we show that they can be leveraged for more effective far‐field terrain classification on future images seen by the robot. A five‐factor, full‐factorial, repeated‐measures experimental evaluation is performed on hand‐labeled data sets taken directly from the problem domain. The experiments result in many statistically significant findings, the most important being that the proposed near‐to‐far Best‐KEnsemble Algorithm, with appropriate parameter selection, outperforms the single‐model, nonensemble baseline approach in far‐field terrain classification. Several other findings that inform the use of near‐to‐far ensemble methods are also presented. © 2009 Wiley Periodicals, Inc.
Generic service composition platform for pervasive E‐Commerce
Authors: Chi Jing , Yin Chunyang , Song Meina , Song Junde , Zhan Xiaosu
Published: January 2009

In this paper, a generic E‐Commerce process model with full E‐Commerce service coverage is propose. Based on this model, a generic service composition platform is proposed as an individual middleware layer to support the pervasive E‐Commerce. The platform consists of an orchestration component and several atomic service components (ASCs). It is in charge of dynamic and automatic general service (GS) construction taking the user preferences and demanded quality of service (QoS) into account. The designed platform is flexible and extensible thanks to the service oriented architecture (SOA) (service oriented architecture)‐based atomic reusable and sharable service components (SCs). And it employs efficient peer‐to‐peer (P2P) interaction between two components. In our method, global QoS is guaranteed by the runtime QoS monitoring and dynamic adjusted two‐dimensional orchestration plan. Copyright © 2009 John Wiley & Sons, Ltd.
Online wind turbine fault detection through automated SCADA data analysis
Authors: Zaher A. , McArthur S.D.J. , Infield D.G. , Patel Y.
Published: January 2009

This paper describes a set of anomaly‐detection techniques and their applicability to wind turbine fault identification. It explains how the anomaly‐detection techniques have been adapted to analyse supervisory control and data acquisition data acquired from a wind farm, automating and simplifying the operators' analysis task by interpreting the volume of data available. The techniques are brought together into one system to collate their output and provide a single decision support environment for an operator. The framework used is a novel multi‐agent system architecture that offers the opportunity to corroborate the output of the various interpretation techniques in order to improve the accuracy of fault detection. The results presented demonstrate that the interpretation techniques can provide performance assessment and early fault identification, thereby giving the operators sufficient time to make more informed decisions regarding the maintenance of their machines. Copyright © 2009 John Wiley & Sons, Ltd.
Effects of habitat fragmentation by damming on salmonid fishes: lessons from white‐spotted charr in Japan
Authors: Morita Kentaro , Morita Shoko H. , Yamamoto Shoichiro
Published: January 2009

Dam construction has serious consequences, and one of the most serious concerns is the fragmentation of riverine ecosystems. We reviewed the influence of habitat fragmentation on white‐spotted charrSalvelinus leucomaenispopulations. First, habitat fragmentation by damming has serious consequences in terms of alternative life‐history strategies. Most fish in dammed‐off areas do not migrate to the sea and instead become resident forms. This loss of the anadromous form negatively affects populations through decreased spawning biomass. In addition, the smaller population sizes in dammed‐off habitats can negatively affect population dynamics through demographic, environmental, and genetic stochasticity. Therefore, the population viability is reduced in small, dammed‐off habitats. White‐spotted charr populations also likely experience different selection pressures after damming. Many of these effects of habitat fragmentation due to damming are not immediate but rather occur gradually over several generations. Because most Japanese dams were constructed after 1970, some effects of damming may not yet be obvious.
Future of the US Healthcare System and the Effects on the Practice of Hand Surgery
Authors: Pushman Allison G. , Chung Kevin C.
Published: January 2009

The multitier healthcare system of the USA has several major flaws. High costs and uncertain quality of care indicate that this system is no longer practical. Several improvement initiatives, such as the Oregon Health Plan, Leapfrog, Lean Manufacturing, and Pay-for-Performance have been implemented into the current system. All of these quality improvement models are being experimented in a limited fashion and do not address the biggest problem in the US healthcare, inequality of care. There is now increasing support for a universal health coverage model as an ethically sound and just way to decrease health disparities in the USA. The current quality initiatives as well as an adoption of universal coverage appear to be the best way to improve quality of care, reduce cost, and increase equality in healthcare. These initiatives may have considerable effects on the practice of hand surgery in the near future, and thus, it is important for the field of hand surgery to become more engaged in advocacy and public policy arena. The purpose of this paper is to examine the current problems in the US healthcare system and to evaluate potential solutions that will enhance quality while simultaneously curbing the unchecked increase in healthcare expenditure.
Metabolic and endocrine effects of metformin and metformin plus cyclic medroxyprogesterone acetate in women with polycystic ovary syndrome
Authors: Haydardedeoglu Bulent , Simsek Erhan , Kilicdag Esra B. , Bagis Tayfun
Published: January 2009

Objective

To evaluate the metabolic and endocrine effects of treatment with cyclic medroxyprogesterone acetate (MPA) plus metformin compared with metformin alone in women with PCOS.

Methods

In this prospective randomized study of women with PCOS, 20 women received 850 mg of metformin twice a day, and 20 women received 850 mg of metformin plus 5 mg of MPA twice a day. Body mass index, hormonal and lipid blood profiles, homocysteine blood level, and insulin sensitivities assessed by homeostasis model assessment (HOMA) were recorded at baseline and at 3 months.

Results

Total cholesterol levels decreased in the metformin plus MPA group (P = 0.002) but did not change significantly in the metformin group (P = 0.159). While homocysteine levels remained unchanged in the metformin plus MPA group, they increased significantly in the metformin group (P = 0.002).

Conclusion

There were no adverse effects of short‐term cyclic MPA plus metformin treatment on metabolic parameters or insulin resistance in patients with PCOS over a 3‐month treatment period.
Consumer reactions to the decreased usage message: The role of elaborative processing
Authors: White Katherine , Willness Chelsea
Published: January 2009

This research examines consumer reactions to an emerging trend among corporate social responsibility initiatives—the promotion of decreased usage of the company's own core products. The results across three experiments suggest that the presence of a decreased usage message that highlights incongruity between the marketing message and the company's goals leads to negative company evaluations. The authors demonstrate that elaborative processing underlies these effects by examining the moderating role of the need for cognition and cognitive load. Further, perceived incongruity and cognitive elaboration mediate the findings. The implications for marketers and consumers are discussed.
Making judgments in a two‐sequence cue environment: The effects of differential cue strengths, order sequence, and distraction
Authors: Biswas Dipayan , Biswas Abhijit , Chatterjee Subimal
Published: January 2009

Consumers frequently evaluate multiple sequential cues of varying strengths in order to draw inferences about a product's quality. The results of three experiments show that when consumers are not distracted, they judge a product's quality more favorably following a strong–weak cue sequence relative to a weak–strong sequence (a primacy effect). However once consumers are distracted from the evaluation task, the primacy effect reverses to a recency effect, whereby consumers judge a product's quality more favorably following a weak–strong cue sequence. Process tests suggest that distraction crowds consumers' short‐term working memory and inhibits the spontaneous rehearsal and the subsequent recall of the cue presented first in the information sequence.
Patterns and implications of Plant-soil δ13C and δ15N values in African savanna ecosystems
Authors: Wang Lixin , D'Odorico Paolo , Ries Lydia , Macko Stephen A.
Published: January 2009

Southern African savannas are mixed plant communities where C3 trees co-exist with C4 grasses. Here foliar δ15N and δ13C were used as indicators of nitrogen uptake and of water use efficiency to investigate the effect of the rainfall regime on the use of nitrogen and water by herbaceous and woody plants in both dry and wet seasons. Foliar δ15N increased as aridity rose for both C3 and C4 plants for both seasons, although the magnitude of the increase was different for C3 and C4 plants and for two seasons. Soil δ15N also significantly increased with aridity. Foliar δ13C increased with aridity for C3 plants in the wet season but not in the dry season, whereas in C4 plants the relationship was more complex and non-linear. The consistently higher foliar δ15N for C3 plants suggests that C4 plants may be a superior competitor for nitrogen. The different foliar δ13C relationships with rainfall may indicate that the C3 plants have an advantage when competing for water resources. The differences in water and nitrogen use likely collectively contribute to the tree–grass coexistence in savannas. Such differences facilitate interpretations of palaeo-vegetation composition variations and help predictions of vegetation composition changes under future climatic scenarios.
Local-Scale Spatial Variability of Soil Organic Carbon and its Stock in the Hilly Area of the Loess Plateau, China
Authors: Wang Yafeng , Fu Bojie , Lü Yihe , Song Chengjun , Luan Yong
Published: January 2009

Soil organic carbon (SOC) is one of the key components for assessing soil quality. Meanwhile, the changes in the stocks SOC may have large potential impact on global climate. It is increasingly important to estimate the SOC stock precisely and to investigate its variability. In this study, Yangjuangou watershed was selected to investigate the SOC distribution under different land uses. We found that SOC concentration decreased with increasing soil depth under all land uses and was significantly different across the vertical soil profile (P < 0.01). However, considering effect of land use on SOC, it is only significant (P < 0.01) in the topsoil (0–5 cm) layer. This indicated that land use has a large effect on the stocks of SOC in the surface soil. The stratification ratio of SOC > 1.2 may mean that soil quality is improving. The order of the SOC density (0–30 cm) under different land uses is forestland > orchard land > grassland > immature forestland > terraced cropland. The SOC stock is found to be as large as 2.67 × 10 t (0–30 cm) in this watershed. Considering time effect of restoration, the slope cropland just abandoned is more efficient for SOC accumulation than trees planted in the semi-arid hilly loess area.
Comparison of Automated 4D‐MSPECT and Visual Analysis for Evaluating Myocardial Perfusion in Coronary Artery Disease
Authors: Hsu Chien‐Chin , Chen Yu‐Wen , Hao Chi‐Long , Chong Jun‐Ted , Lee Chun‐I , Tan Hau‐Tong , Wu Ming‐Sheng , Wu Jung‐Chou
Published: January 2009

The aim of this study was to assess the reproducibility and diagnostic performance for coronary artery disease (CAD) of an automated software package, 4D‐MSPECT, and compare the results with a visual approach. We enrolled 60 patients without previously known CAD, who underwent dual‐isotope rest Tl‐201/stress Tc‐99m sestamibi myocardial perfusion imaging and subsequent coronary angiography within 3 months. The automated summed stress score (A‐SSS), summed rest score (A‐SRS) and summed difference score (A‐SDS) were obtained using a 17‐segment five‐point scale model with 4D‐MSPECT. For intraobserver and interobserver variability assessment, automated scoring was done by a nuclear medicine physician twice and by a nuclear medicine technologist. The visual summed stress score (V‐SSS), summed rest score (V‐SRS), and summed difference score (V‐SDS) were obtained by consensus of two nuclear medicine physicians. The intraobserver and interobserver agreements of automated segmental scores were excellent. The intraobserver and interobserver summed scores also correlated well. Agreements between visual and automated segmental scores were moderate (weighted κ of 0.55 and 0.50 for stress and rest images, respectively). Correlations between automated and visual summed scores were high, with correlation coefficients of 0.89, 0.85 and 0.82 for SSS, SRS and SDS, respectively (all p < 0.001). The receiver operating characteristic area under the curve for diagnosis of CAD by V‐SSS, V‐SDS, A‐SSS and A‐SDS were 0.78 ± 0.06, 0.87 ± 0.05, 0.84 ± 0.05 and 0.90 ± 0.04, respectively. A‐SDS had better diagnostic performance than A‐SSS and V‐SSS (p = 0.043 and p = 0.032, respectively), whereas there was no statistically significant difference between A‐SDS and V‐SDS (p = 0.56). Using V‐SDS ≥ 2 as a diagnostic threshold, the sensitivity, specificity, and accuracy for CAD were 83.7%, 76.5% and 81.7%, respectively. Using A‐SDS ≥ 3 as a diagnostic threshold, the sensitivity, specificity, and accuracy for CAD were 79.1%, 82.4% and 80.0%, respectively. In conclusion, the reproducibility of automated semiquantitative analysis with 4D‐MSPECT was excellent. The diagnostic performance of automated semiquantitative analysis with 4D‐MSPECT was comparable with the visual approach.
Health‐related Quality of Life Taiwanese Dialysis Patients: Effects of Dialysis Modality
Authors: Mau Lih‐Wen , Chiu Herng‐Chia , Chang Pi‐Yu , Hwang Su‐Chen , Hwang Shang‐Jyh
Published: January 2009

Taiwan has the highest incidence and prevalence of end‐stage renal disease worldwide. However, not many studies have focused on the influence of dialysis modality on health‐related quality of life (HRQoL) for dialysis patients in Taiwan. This study intended to compare the differences in HRQoL between peritoneal dialysis (PD) and hemodialysis (HD) and to evaluate the effects of dialysis modality on patient HRQoL. A cross‐sectional survey using the Taiwan‐version 36‐item short‐form health survey questionnaire (SF‐36) was completed by 244 dialysis patients (58 PD and 186 HD patients) at two hospital‐based dialysis units in southern Taiwan. Patient characteristics, diagnoses and laboratory data were individually extracted from the annual survey and matched with primary HRQoL data. Multiple linear regression analysis was performed to evaluate the effects of dialysis modality on HRQoL. Compared with HD patients, PD patients had higher scores in six of the eight SF‐36 subscales, including physical functioning, role limitations due to physical and emotional problems, bodily pain, vitality, and mental health. However, only role limitations due to emotional problems and bodily pain reached significant difference levels (p < 0.05). After controlling for patient characteristics, comorbid conditions and laboratory values, the bodily pain score was 7.88 points higher for PD patients compared with HD patients, while the social functioning score was 9.00 points higher for HD patients compared with PD patients (p < 0.05). The present study provides cross‐sectional confirmation for equivalent levels of HRQoL between PD and HD patients except for the subscales of bodily pain and social functioning. In addition to dialysis modality, HRQoL for dialysis patients may be more related to personal attributes, interactions with multiple diseases, social support and quality of care received. When informing patients about modality choices for dialysis, trade‐offs should be discussed and individual preferences for specific aspects of HRQoL should be considered.
Accumulation of Tc‐99m HL91 in Tumor Hypoxia: In Vitro Cell Culture and In Vivo Tumor Model
Authors: Lee Bi‐Fang , Chiu Nan‐Tsing , Hsia Chien‐Chung , Shen Lie‐Hang
Published: January 2009

Hypoxic cells within a tumor can account, in part, for resistance to radiotherapy and chemotherapy. Indeed, the oxygenation status has been shown to be a prognostic marker for the outcome of therapy. The purpose of this study was to determine whether Tc‐99m HL91 (HL91), a noninvasive imaging tracer, detects tumor hypoxia in vitro in cell culture and in vivo in a tumor model. Uptake of HL91 in vitro into human lung cancer cells (A549) and murine Lewis lung cancer cells (LL2) was investigated at oxygen concentrations of 20% O2 (normoxia), and 1% O2 (hypoxia). HL91 biodistribution was studied in four groups: severe combined immune deficiency (SCID) mice bearing A549 tumors, C57BL/6NCrj (B6) mice bearing LL2 tumors, SCID controls, and B6 controls. Accumulation of the tracer was compared between tumors treated with hydralazine or phosphate‐buffered saline (PBS). Scintigraphic images were obtained for hydralazine‐treated mice and PBS‐treated mice in each of the four study groups. Autoradiography of tumor slices was also acquired. In vitro studies identified hypoxia‐selective uptake of HL91, with significantly increased uptake in the hypoxic state than in the normoxic state. Biodistribution and scintigraphy showed increased HL91 uptake during tumor hypoxia at 0.5 hours, and there was progressively increased activity for up to 4 hours after tracer administration. HL91 accumulation in tumor hypoxia was markedly increased in mice treated with hydralazine compared with those treated with PBS. Autoradiography revealed high HL91 uptake in the peripheral areas around the necrotic regions of the tumor, which were identified by histologic examination. HL91 exhibits selectivity for tumor hypoxia both in vitro and in vivo and provides a successful imaging modality for the detection of tumor hypoxia in vivo.
Associated Risk Factors for Abnormal Ankle‐brachial Index in Hemodialysis Patients in a Hospital
Authors: Chen Szu‐Chia , Su Ho‐Ming , Mai Hsiu‐Chin , Chen Jui‐Hsin , Chen Chiu‐Yueh , Chang Jer‐Ming , Chen Hung‐Chun
Published: January 2009

Ankle‐brachial index (ABI) is a marker for peripheral artery disease and can predict mortality in hemodialysis patients. However, it is seldom studied in southern Taiwan, an area with high prevalence of end‐stage renal disease (ESRD). The aim of this study was to investigate the prevalence and associated risk factors for peripheral artery disease in the ESRD population in a hospital. All routine hemodialysis patients in one regional hospital were included except for six patients who refused ABI examinations and four patients with atrial fibrillation. Finally, 225 patients formed our study group. ABI was measured using an ABI‐form device (Colin VP1000). The prevalence of ABI < 0.9 and 3 1.3 was 15.6% and 5.8%, respectively. ABI < 0.9 was independently associated with advanced age (p = 0.027), increased pulse pressure (p = 0.005), increased hemat‐ocrit (p = 0.008) and decreased serum albumin level (p = 0.009). In addition, ABI 3 1.3 was significantly associated with diabetes mellitus (p = 0.019). This study demonstrated the associated risk factors of peripheral artery disease in patients with hemodialysis in a hospital. ESRD patients of advanced age and with increased pulse pressure, increased hematocrit and decreased serum albumin level had a relatively high risk for ABI < 0.9 and patients with diabetes had a relatively high risk for ABI 3 1.3.
Mycobacterium abscessus Endocarditis: A Case Report and Literature Review
Authors: Tsai Wei‐Chung , Hsieh Hsiao‐Cheng , Su Ho‐Ming , Lu Po‐Liang , Lin Tsung‐Hsien , Sheu Sheng‐Hsiung , Lai Wen‐Ter
Published: January 2009

Infective endocarditis owing to Mycobacterium abscessus infection is rarely reported. Most cases of infective endocarditis caused by Mycobacterium abscessus are seen in patients after valve replacement. Although early surgical intervention is recommended and medical treatment with antibiotics according to the susceptibility to the pathogen, such as amikacin, imipenem, cefoxitin, quinolones and macrolides, are applied, the course of such endocarditis is usually subacute and often has fatal outcomes. The present case was a 29‐year‐old male patient who was an intravenous drug user who had recurrent endocarditis caused by Mycobacterium abscessus. Unusually, our reported case was infected on his native valve. However, we experienced recurrence despite antimicrobial therapy. For culture‐negative endocarditis, physicians should consider the possibility of Mycobacterium abscessus infection and related treatment difficulties.
Metachronous Thyroglossal Duct Cyst and Inferior Parathyroid Cyst: A Case Report
Authors: Cheng Chueh‐Yi , Chang Yih‐Leong , Hsiao Jong‐Kai , Wang Cheng‐Ping
Published: January 2009

Thyroglossal duct cysts (TDC) are the most common cervical cysts and are usually considered to be a benign embryonic malformation where the thyroglossal duct fails to obliterate. Parathyroid cysts (PTC) are a rare disease and may also result from malformation of the remnants of the third pharyngeal pouch. Although several sporadic cases of concurrent TDC with other head and neck malformations have been reported in the literature, a combination of TDC and PTC has never been reported. Here, we report the first case of a 35‐year‐old woman with a metachronous TDC and PTC. The embryologic origins of TDCs and inferior PTCs are revealed from the experience of this case.
Catheter Migration After Implantationan Intrathecal Baclofen Infusion Pump for Severe Spasticity: A Case Report
Authors: Li Tung‐Chou , Chen Mei‐Hsiu , Huang Jing‐Shan , Chan Jun‐Yeen , Liu Yaun‐Kai , Chen Ming‐Hong
Published: January 2009

We report a case of intrathecal baclofen infusion pump implantation complicated by migration of the catheter tip. A 55‐year‐old man required an intrathecal baclofen infusion for severe spasticity 4 years after a cervical spinal cord injury with incomplete tetraparesis. Twelve months after initial implantation of the device, the patient began to experience a recurrence of trunk tightness and spasticity. Subsequent X‐ray and computed tomography evaluations of the catheter system revealed pooling of contrast medium outside of the intrathecal distribution in the lumbar subcutaneous region of the back and therefore migration of the pump catheter tip. At surgical revision, emphasis was placed on minimizing the length of catheter outside of the spine and securing the catheter in the supraspinous fascia with a right‐angled anchor. The distance between the anchors and the entry point of the catheter into the supraspinous fascia was also reduced to prevent slipping when the patient bends forward. After surgery, the patient's spasticity improved and, 1 year later, he has experienced no further complications during follow‐up, requiring an average baclofen dose of 150 mg/day. Here, we describe several surgical methods intended to secure the intrathecal catheter and prevent catheter migration. Other complications related to catheter failure are also highlighted.
Burr Hole Drainage for Complicated Spontaneous Intracranial Hypotension Syndrome
Authors: Liu Yu‐Fang , Lin Hung‐Lin , Cho Der‐Yang , Chen Chun‐Chung , Lo Yu‐Chien , Chiou Shang‐Ming
Published: January 2009

Spontaneous intracranial hypotension is a potentially severe condition that is caused by continuous cerebrospinal fluid leakage. Clinically, most patients have a benign course and the condition remits after conservative management. We report two consecutive patients who presented with acute expansion of subdural collection and disturbed consciousness. Both patients recovered completely after undergoing burr hole drainage.
Hybridräume
Authors: Nissen Sylke
Published: January 2009

The main characteristics of public space are accessibility and usability for all citizens. Current developments primarily observed in cities, however, point to the fact that the distinction between public and private is becoming blurred. Instead urban spaces of hybrid character are emerging. Spaces with public functions like train stations, parks or pedestrian areas change character; semi-private spaces like malls or plazas expand. In order to obtain a realistic assessment of these developments the paper offers a critical appraisal of recent privatization trends followed by a brief systematization. After a discussion of feasible reasons for the loss of public space, the paper considers potential implications for the future of citizenship.
Note on Milner's Lamp
Authors: Professor Tait
Published: January 2009

This curious device is figured at p. 149 of De Morgan's Budget of Paradoxes, where it is described as a “hollow semi-cylinder, but not with a circular curve,” revolving on pivots. The form of the cylinder is such that, whatever quantity of oil it may contain, it turns itself till the oil is flush with the wick, which is placed at the edge.
A family of quadrics
Authors: Brown L. M.
Published: January 2009

In a recent paper I have discussed the families of quadrics in [2n] which are obtained by causing the members to have the greatest possible number of fixed [n – 1]'s or “generators.” It was found possible to fix four [n – 1]'s in general position; the family of quadrics through these possessed a “base” variety, common to all the members, which consisted of a highly degenerate Vn–1. Here I consider the same problem for quadrics in [2n + 1], find how many generators may be assigned arbitrarily and discuss the common part of the quadrics which pass through such generators.
C*-Algebras of inverse semigroups
Authors: Duncan J. , Paterson A. L. T.
Published: January 2009

There are various algebras which may be associated with a discrete group G. In particular we may consider the complex group ring ℂG, the convolution Banach algebra l1(G), the enveloping C*-algebra C*(G) of l1(G), and the reduced C*-algebra determined by the completion of l1(G) under the left regular representation on l2(G). There is a substantial literature on the circle of ideas associated with the embeddings
On certain semigroups arising from radicals of matrix rings
Authors: Sands A. D.
Published: January 2009

By a ring we shall mean an associative ring not necessarily containing an identity element. The fundamental definitions and properties of radicals may be found in Divinsky [2]. Similarly we refer to Howie [3] for the semigroup concepts.

If R is a ring Mn(R) will denote the ring of n × n matrices with entries from R. For many important radicals α it has been shown that α(Mn(R)) = Mn(α(R)) for all rings R and all positive integers n. However this is not the case for all radicals α. Associated with each radical α we define a set of positive integers S(α) by
On a problem of M. P. Schützenberger
Authors: McAlister D. B.
Published: January 2009

A class of finite semigroups is called a genus if it is closed under homomorphic images, subsemigroups and finite direct products. During a talk at the Symposium on Semigroups held at the University of St Andrews, in 1976, M. P. Schützenberger posed the problem of characterising the smallest genus which contains finite groups and finite semigroups, all of whose subgroups are trivial.
Some bifurcation problems in cholesteric liquid crystal theory
Authors: Barratt P. J. , Fraser C.
Published: January 2009

A liquid crystal is a transversely isotropic liquid consisting of large, relatively rigid, elongated molecules which align more or less parallel to their neighbours. Three distinct types of liquid crystal occur, namely nematic, cholesteric and smectic. In the absence of any external influences, nematics tend to orientate with their anisotropic axis uniformly aligned, whereas cholesterics prefer a characteristic helical configuration and smectics are more highly organised in layered structures. However, it is possible to influence the orientation of the anisotropic axis by a variety of external means. In particular, solid surfaces affect the alignment through the action of surface torques, while electromagnetic fields exert body torques which tend to align the anisotropic axis either parallel or perpendicular to the applied field. Detailed descriptions of the physical properties of liquid crystals may be found in the books by de Gennes [1] and Chandrasekhar [2] and the review by Stephen and Straley [3].
Note on a paper by Singh and Dhaliwal
Authors: Williams W. E.
Published: January 2009

In a recent paper (1) Singh and Dhaliwal present an analysis which purports to solve a pair of dual integral equations which occur in crack theory and the object of this note is to demonstrate that their analysis is erroneous.
On the nonexistence of L2-solutions of nth order differential equations
Authors: Grammatikopoulos M. K. , Kulenović M. R.
Published: January 2009

Consider the equation

where is the generalised derivative of x defined as follows: for every t ≧ T

.
Three counterexamples concerning ω-chain completeness and fixed point properties
Authors: Mashburn J. D.
Published: January 2009

A partially ordered set, is ω-chain complete if, for every countable chain, or ω-chain, in P, the least upper bound of C, denoted by sup C, exists. Notice that C could be empty, so an ω-chain complete partially ordered set has a least element, denoted by 0.
Apolar Triads on a Cubic Curve
Authors: Sandler W.
Published: January 2009

Professor W. P. Milne has shown that if a pencil of plane cubic curves cut in two triads of points which are apolar to the members of the pencil, then the other three points of intersection also form an apolar triad to the pencil. I propose to show how to obtain a simple geometrical construction for the third apolar triad though the cubics in this case are not perfectly general. The method of approach is by means of Grassmann's construction for a cubic curve and the use of apolar theorems established for a curve described in this manner.
The Absolute Summability of Fourier Series
Authors: Whittaker J. M.
Published: January 2009

An elementary proposition states that an absolutely convergent series is convergent, i.e. that if

then
On the Reduction of Singular Matrix Pencils
Authors: Turnbull H. W.
Published: January 2009

The following rational method of dealing with the reduction of a singular matrix pencil to canonical form has certain advantages. It is based on the principle of vector chains, the length of the chain determining a minimal index. This treatment is analogous to that employed by Dr A. C. Aitken and the author in Canonical Matrices (1932) 45–57, for the nonsingular case. In Theorems 1 and 2 tests are explicitly given for determining the minimal indices. Theorem 2 gives a method of discovering the lowest row (or column) minimal index. Theoretically it should be possible to state a corresponding theorem for each of these indices, not necessarily the lowest, and prior to any reduction of the pencil. This extension still awaits solution.
The intersection of certain quadrics
Authors: Brown L. M.
Published: January 2009

We investigate in this paper a certain special family of quadric varieties, that is of in [R]. Now among the more important properties of a quadric in [R] is that it possesses a system or systems of “ generators,” i.e., the quadric may be taken as the locus of certain families of subspaces, the behaviour of these depending on the parity of R. If R is even, a quadric V2n–1 in [2n] contains a single family of [n—l]'s, so it seems likely that in discussing special families of quadrics in [2n] an important type will be obtained by constraining the quadric to pass through a number of [n — l]'s.
Some combinatorial problems of finite abstract algebra
Authors: Richardson A. R.
Published: January 2009

The elements of the abstract number systems termed groups, rings, ideals, modules and algebras are mere symbols arranged in systems by means of consistent and independent postulates which isolate these systems from the complete realm of abstract mathematics. The postulates are usually chosen so as to generalise the special number systems which have been noticed in traditional mathematics and their independence and consistenc}" are usually proved by means of numerical examples. It is suggested in this note that the extents of the consistency and independence of a set of postulates should also be studied
Note on the derivation and distribution of Pearson's x2
Authors: Aitken A. C.
Published: January 2009

The object of this note is to deduce from first principles the probability differential of Pearson's x2, and to account for “degrees of freedom.”
Integrals involving Bessel and Legendre functions
Authors: Lowndes J. S.
Published: January 2009

Felsen (1) has shown that when a plane wave is incident along the axis of a rigid cone of narrow apex angle an approximate expression for the scattered wave involves an integral of the form

where is a Bessel function of the third kind, k a constant and , is the Legendre (conical) function of the first kind.
An extension of the Minkowski determinant theorem
Authors: Marcus Marvin , Gordon William R.
Published: January 2009

Minkowski proved the following (for a proof see (4)): if A and B are n × n positive semi-definite hermitian matrices then

It is known (4) that if both A and B are non-singular, then the equality holds in (1) if and only if B = cA where c is a positive number.
Closure operations and group algebras
Authors: Meldrum J. D. P. , Wallace D. A. R.
Published: January 2009

Let G be a group and let K be a field. The twisted group algebra Kt(G) of G over K is defined as follows: let G have elements a, b, c, … and let Kt(G) be the vector space over K with basis elements ; let α: G ×G → K be a 2-cocycle and define a multiplication on Kt(G) by

extending this by linearity to Kt(G) yields an associative algebra. We are interested in information concerning the Jacobson radical of Kt(G), denoted by JKt(G).
Generalised quaternion groups and distributively generated near-rings
Authors: Malone J. J.
Published: January 2009

In this paper two major questions concerning generalised quaternion groups and distributively generated (d.g.) near-rings are investigated. The d.g. near-rings generated, respectively, by the inner automorphisms, automorphisms, and endomorphisms of the group are described. It is also shown that these morphism near-rings are local near-rings and contain no non-trivial idempotents. Finally, it is demonstrated that exactly 16 d.g. near-rings can be defined on a given generalised quaternion group.
On identities associated with a discriminant
Authors: Newell M. J.
Published: January 2009

If the elements of a symmetric matrix lie in the real field it is well known that the roots of its characteristic equation are real. This implies that the discriminant of that equation (i.e. the product of the squared differences of the roots) is a polynomial in the elements which is non-negative and the same must be true for the leading coefficients of all the other Sturm functions associated with the characteristic equation. One would expect that it should be possible to express them as a sum of squares. Conversely, such an expression would establish the reality of the roots.
A note on an inequality with non-conjugate parameters
Authors: Walker P. L.
Published: January 2009

The inequality

which is valid for positive, non-null f, g in the spaces Lp(0, ∞), Lq(0, ∞), where p > 1, (1/p)+(1/q) = 1, is a well-known generalisation of the classical inequality of Hilbert (see for instance Chapter 9 of Hardy, Littlewood, and Polya (1)).
On compactification of mappings
Authors: Firby P. A.
Published: January 2009

If X and Y are Tychonoff spaces then the continuous function f mapping X onto Y is said to be compact (perfect, or proper) if it is closed and point inverses are compact. If h is a continuous function mapping X onto Y then by a compactification of h we mean a pair (X*, h*) where X* is Tychonoff and contains X as a dense subspace, and where h*: X*→Y is a compact extension of h. The idea of a mapping compactification first appeared in (7). In (1) it was shown that any compactification of X determines a compactification of h, and that any compactification of h can be determined in this way. This idea was then developed in (2) and (3).
Basic sequences in F-spaces and their applications
Authors: Kalton N. J.
Published: January 2009

The aim of this paper is to establish a conjecture of Shapiro (10) that an F-space (complete metric linear space) with the Hahn-Banach Extension Property is locally convex. This result was proved by Shapiro for F-spaces with Schauder bases; other similar results have been obtained by Ribe (8). The method used in this paper is to establish the existence of basic sequences in most F-spaces.
Locally bounded spaces
Authors: Lambrinos P. Th.
Published: January 2009

The three common definitions of local compactness require, respectively, each point to have a compact neighbourhood, a neighbourhood basis consisting of compact sets, or a closed compact neighbourhood. These definitions are equivalent in Hausdorff or in regular spaces but not in general (3, 7).
The Diffraction of Transient Electro-Magnetic Waves by a Wedge
Authors: Butcher A. C. , Lowndes J. S.
Published: January 2009

Much of the work on the theory of diffraction by an infinite wedge has been for cases of harmonic time-dependence. Oberhettinger (1) obtained an expression for the Green's function of the wave equation in the two dimensional case of a line source of oscillating current parallel to the edge of a wedge with perfectly conducting walls. Solutions of the time-dependent wave equation have been obtained by Keller and Blank (2), Kay (3) and more recently by Turner (4) who considered the diffraction of a cylindrical pulse by a half plane.
Common Transversals
Authors: Rankin R. A.
Published: January 2009

A well-known theorem in group theory [(8), p. 11, Satz 3] asserts that, whenHis a subgroup of finite index in a groupG, there exists a system of common representatives of the right cosets and the left cosets ofHinG. Various proofs and generalisations, mainly involving combinatorial rather than grouptheoretical ideas, are known, and an excellent account of the subject is to be found in Chapter 5 of Ryser's book (6), where references to the literature are given. The purpose of the present paper is to use group-theoretical ideas to prove theorems of a similar nature. The motivation for this work comes from the theory of Hecke operators, and one of the main objects is to provide a simple proof of a result given by Petersson (4), which is needed in order to prove the normality of these operators.
The normal vibrations of a rigid spherical punch on the surface of an elastic half-space
Authors: Crozier R. J. M. , Hunter S. C.
Published: January 2009

A rigid spherical punch vibrates normally on the surface of a semi-infinite isotropic elastic half-space. The essential novelty of this problem, which is treated within the context of classical elasticity, is that of a changing boundary; the radius of the circle of contact on the free surface varies with time. The geometrical co-ordinates are modified to yield a boundary value problem with fixed boundaries. However the governing differential equations become more complicated. These equations are solved by a perturbation procedure for the case where the contact radius a(t) is of the form

where a0 is constant and |ŋ(t)≪1. Finally the normal stress and the total load under the punch are evaluated in the form of series which are valid for sufficiently slowly varying ŋ(t).
Relations between (N, pn) and (, pn) summability
Authors: Kuttner Brian , Rhoades B. E.
Published: January 2009

Let {pn} be a positive sequence. The Nörlund transformation (N, pn) maps the sequence {Sn} into the sequence {tn} by means of the equation

where
On a problem of Baayen and Kruyswijk
Authors: Burgess D. A.
Published: January 2009

We shall call a finite semigroup S arithmetical if there exists a positive integer N and a monomorphism μ of S into the multiplicative semigroup RN of the ring of residue classes of the integers modulo N. In 1965 P. C. Baayen and D. Kruyswijk [1] posed the problem' Is every finite commutative semigroup arithmetical? ' The purpose of this paper is to answer this question.
Arithmetical identities and Hecke's functional equation
Authors: Berndt Bruce C.
Published: January 2009

We consider a subclass of the Dirichlet series studied by Chandrasekharan and Narasimhan in (1). Our objective is to generalize some identities due to Landau (3) concerning r2(n), the number of representations of the positive integer n as the sum of 2 squares. We shall also give a slight extension of Theorem III in (1).
Bounds for permanents of non-negative matrices
Authors: Minc Henryk
Published: January 2009

Let v = (a1 …, an) be a real n-tuple and be the numbers a1 …, an arranged in decreasing order. Let denote the sum of m greatest components of v and the sum of m smallest components of v, i.e.,
On distributively generated near-rings
Authors: Lich Steve
Published: January 2009

The following theorems in ring theory are well-known:

1. Let R be a ring. If e is a unique left identity, then e is also a right identity.

2. If R is a ring with more than one element such that aR = R for every nonzero element a ε R, then R is a division ring.

3. A ring R with identity e ≠ 0 is a division ring if and only if it has no proper right ideals.
The Simple Pendulum with Uniformly Changing String Length
Authors: Brearley M. N.
Published: January 2009

An analysis is made of the motion of a simple undamped pendulum which performs small oscillations in one plane while its string is raised or lowered through the point of support at a constant rate. The behaviour of the system and the variation of its angular and linear amplitudes are expressible in terms of Bessel functions of orders 0, 1 and 2.
A Theorem on Bordering Symmetrical Determinants whose Elements are of the form araaas
Authors: Nassau J. J.
Published: January 2009

The following is a generalization of a theorem stated by Professor H. S. Uhler and demonstrated by the writer in the American Mathematical Monthly of October 1927.
A Note on the Transformability of Spherically Symmetric Metrics
Authors: Kustaanheimo Paul
Published: January 2009

It is shown that every spherically symmetric metric can be transformed into the isotropic form. As illustration an example is given.
Tensor Integrals
Authors: Fabian William
Published: January 2009

A form of integration of tensors will be introduced here, which will preserve the character of a tensor when so integrated.