bluuebunny/crossref_metadata_2025 huggingface dataset:
On the Interaction of Surface Waves and Upper Ocean Turbulence
Authors: Ardhuin Fabrice , Jenkins Alastair D.
Published: April 2006

The phase-averaged energy evolution for random surface waves interacting with oceanic turbulence is investigated. The change in wave energy balances the change in the production of turbulent kinetic energy (TKE). Outside the surface viscous layer and the bottom boundary layer the turbulent flux is not related to the wave-induced shear so that eddy viscosity parameterizations cannot be applied. Instead, it is assumed that the wave motion and the turbulent fluxes are not correlated on the scale of the wave period. Using a generalized Lagrangian average it is found that the mean wave-induced shears, despite zero vorticity, yield a production of TKE as if the Stokes drift shear were a mean flow shear. This result provides a new interpretation of a previous derivation from phase-averaged equations by McWilliams et al. It is found that the present source or sink of wave energy is smaller but is still on the order of the empirically adjusted functions used for the dissipation of swell energy in operational wave models, as well as observations of that phenomenon by Snodgrass et al.
Contrasting Characteristics of Convection over the Northern and Southern South China Sea during SCSMEX
Authors: Ciesielski Paul E. , Johnson Richard H.
Published: April 2006

Observations from two enhanced sounding arrays during the May–June 1998 South China Sea Monsoon Experiment (SCSMEX) are used to determine and contrast the properties of convection over the northern and southern South China Sea (SCS). A regression analysis between SST data and monthly rainfall indicates that the ENSO signal exerted a strong influence on the rainfall distribution over the SCS during SCSMEX. This resulted in wetter-than-normal conditions along the south China coast and northern SCS, and generally drier-than-average conditions elsewhere, particularly over the Philippine Islands.

The monsoon onset as determined by a shift in the low-level winds from easterly to southwesterly over the SCS occurred around mid-May. Over the southern enhanced sounding array (SESA), the onset was characterized by a rainy period associated with the passage of a convectively coupled Kelvin wave. This was followed by a weeklong break and then several episodic rain events with increasingly higher rain rates. Rainfall over the northern enhanced sounding array (NESA), which was largely out of phase with SESA rainfall events, occurred primarily during two 10-day periods separated by a weeklong break. Convective characteristics over the SESA, deduced primarily from heat and moisture budget profiles, indicate a high stratiform rain fraction consisting of alternating periods with decaying mesoscale systems that organized near the western Borneo coastline and shallower convective clouds. In contrast, NESA-averaged profiles were indicative of deep convection with a relatively small stratiform rain fraction, which was confirmed with radar analyses during the onset convective period.

The diurnal cycle of convection is a dominant feature throughout much of the SCS. Over both budget regions, early morning (0500–0800 LT) convective systems were frequently initiated near the coasts, then gradually dissipated during the course of the day as the midlevel steering currents moved the systems away from the coastline. These decaying convective systems resulted in an early afternoon (1400 LT) rainfall peak over both sonde arrays.
A crosslinguistic study of children's noun learning: The case of object and substance words
Authors: Subrahmanyam Kaveri , Chen Hsin-Hua Nancy
Published: April 2006

The study reported in this paper uses a crosslinguistic approach to investigate universal versus language-specific influences on children's attention when learning object and substance names. We compared English- and Mandarin Chinese-speaking 3- and 4-year-old children and adults' attention to shape versus material in a labeling and non-labeling task. Participants saw either an object or substance standard in the context of either a labeling (‘Is this also the riff?’) or non-labeling task (‘Is this the same as this?’). On the labeling task, 3-year-old Chinese speakers attended to shape, whereas 4-year-old and adult Chinese speakers attended to material, regardless of whether the standard was an object or a substance. Among English speakers, 3-year-olds attended to shape when labeling the object and substance standards, 4-year-olds showed a preference for shape when labeling the object but no preference between shape and material when labeling the substance standard. English-speaking adults showed a preference toward shape when labeling the object standard and material when labeling the substance standard. On the non-labeling task, 4-year-old and adult Chinese speakers attended to material, whereas younger Chinese speakers attended to shape; English speakers of all ages attended to shape, with 4-year-olds and adults showing greater attention to shape in the non-labeling task compared to the labeling task. The results are discussed in terms of language general and language-specific processes in word learning.
Dynamic event words: From common cognition to varied linguistic expression
Authors: McCune Lorraine
Published: April 2006

Interpretation of single dynamic event words through the lens of motion-event semantics yields a picture of continuity across development. A claim of continuity from children's pre-linguistic cognition through the single-word period to first sentences might seem to imply a reliance on early ‘concepts’. In contrast, the cognitive structure of the sensorimotor period is characterized here as nonconceptual, with children dependent on language to mold this consistent early cognition toward concepts. Single dynamic event words comprise the same basic domains across languages, but vary in their analysis of those domains in response to characteristics of the ambient language. Dynamic event word meanings based on pre-linguistic cognition further provide the foundation for meanings observed in the verbs of early sentences. These same early verbs are those most likely to be grammaticalized across the world's languages, yielding an interesting correspondence between meanings derived from sensorimotor cognition and those contributing to grammatical expression (Ninio, 1999a). Given their central status in early language expression, dynamic event words should be recognized as comprising a critical category of single-word meanings.
The Relationship Between School-Aged Bullying and Trust, Shyness and Quality of Friendships in Young Adulthood
Authors: Jantzer Amanda M. , Hoover John H. , Narloch Rodger
Published: April 2006

We collected data on 170 college students to assess retrospective perception of school-aged bullying experiences, hardiness and aspects of friendships and romantic relationships on the dimensions of trust, relationship quality and shyness. We found that rates of reported victimization were positively correlated with contemporaneous shyness levels. We also noted a statistically significant, inverse relationship between retrospective victimization levels and both friendship quality and trust.
Cyberbullying in Schools
Authors: Li Qing
Published: April 2006

This study investigates the nature and the extent of adolescences’ experience of cyberbullying. A survey study of 264 students from three junior high schools was conducted. In this article, ‘cyberbullying’ refers to bullying via electronic communication tools. The results show that close to half of the students were bully victims and about one in four had been cyber-bullied. Over half of the students reported that they knew someone being cyberbullied. Almost half of the cyberbullies used electronic means to harass others more than three times. The majority of the cyber-bully victims and bystanders did not report the incidents to adults. When gender was considered, significant differences were identified in terms of bullying and cyberbullying. Males were more likely to be bullies and cyberbullies than their female counterparts. In addition, female cyberbully victims were more likely to inform adults than their male counterparts.
Communication Networking: ICTs and health information in Africa
Authors: Ojo Tokunbo
Published: April 2006

This paper examines the uses of information and communication technologies (ICTs) in the African health sector. In particular, it shows the benefits that ICTs can bring to African health care systems in the areas of medical information, clinical data exchange, treatment, health education campaigns and international collaboration between African medical experts and their colleagues abroad. Despite the potential benefits and uses of ICTs, the paper warns that ICTs should not be naively celebrated as the panacea of African health care. It suggests that ICTs should be a means, not an end, for development in Africa. In this context, the paper illustrates how ICTs can be adapted for human development, social capabilities and literacy within African society.
Rurality and Labor Process Autonomy
Authors: Hairong Yan
Published: April 2006

This article examines the experiences of baomu in the Mao era and in the post-Mao era China. While baomu conducted their work in the form of wage labor and have been subjected to similar structural inequality as domestic workers, significant differences exist in the relations and processes of labor and bear out the political epistemic differences between the two eras. Central to my examination is whether domestic workers have autonomy in their labor process and what structural and ideological conditions enable or disable their autonomy. I argue that valorization or denigration of rurality played a key role to enable or disable labor process autonomy. To draw connections and disconnections between domestic service in the two eras and to capture China' transition to postsocialism, I suggest that migrant domestic workers' subsumption to wage labor was formal in the Mao era and real in the post-Mao era.
A Northern New Mexican ‘Fix’
Authors: Trujillo Michael L.
Published: April 2006

Sandwiched between the artist colonies and tourist centers of Santa Fe and Taos, northern New Mexico's greater EspaÒola Valley is a New Mexican Hispanic or Nuevomexicano enclave and often considered a bastion of traditional Nuevomexicano culture. Despite the valley's location, this area remains off the artist and tourist track. Moreover, regional and national media sources report that the valley is a site of widespread heroin use. This article focuses on the act of using drugs in a place elaborately scripted by discourses that idealize Nuevomexicano traditional culture. In particular, this article (1) unpacks the conceptualization of culture as a cure for the problems that affect the community, (2) situates the study of drug use in EspaÒola in a wider ethnographic context of drug use, and (3) suggests that drug use provides a momentary ‘fix’ that both reconciles and manifests the contradictions of many Nuevomexicanos’ lived experiences.
Performance Information for Democracy
Authors: Pollitt Christopher
Published: April 2006

This article examines research into the use of performance information by ministers, parliamentarians and citizens. These ‘end users’ are of crucial importance to the claim that performance information is not merely managerially useful, but also contributes to the quality of democratic debate and to the ability of citizens to make choices. A literature review indicates that research into use by these groups has been very patchy, and that much of what we do know suggests that evaluations and performance reports and audits are seldom highly valued by politicians or citizens. Possible reasons and remedies for this apparent state of affairs are discussed, and areas for further research are suggested.
Global entertainment and local celebration
Authors: Reijnders Stijn , Rooijakkers Gerard , van Zoonen Liesbet
Published: April 2006

The entertainment show Idols has been without doubt one of the most popular TV programmes internationally in recent years. In the wake of this talent quest, local ‘Idols parties’ were organized throughout the Netherlands in 2003 and 2004. At schools, cafes, camping sites and clubrooms, parties were staged with names such as ‘Idols Night’ or ‘Gay Idols’. This article examines the meaning of these shows and what the phenomenon ultimately tells us about the relationship between television culture and popular culture. To this end, we attended eight Idols parties, conducting ethnographic fieldwork. We can conclude that the Idols parties are inspired to a great extent by the popular TV format, but at the same time the ritual character of the TV model is diluted to make room for a process of appropriation. The objective of each Idols party is to celebrate the group identity of their association, school or club.
Governing women's morality
Authors: Atasoy Yildiz
Published: April 2006

The veiling of Muslim women is subject to strongly contested ideas about whether the veil is a symbol of women's subordination to an oppressive tradition or a means of emancipation from that tradition. This article suggests that women's own personal reasons for veiling must be analysed. Data collected from published documents from Muslim organizations allows for demonstration that the veil is configured as central to an Islamic moral code of female modesty. A further analysis of findings from interviews conducted with veiled Muslim women in Winnipeg shows the nuanced ways in which women enact this code.
Gendered mobility, the nation and the woman's page
Authors: Gabriele Sandra
Published: April 2006

This article explores the domestic travel writing of two women journalists who wrote for competing partisan papers in Toronto – Kit Coleman of The Daily Mail and Faith Fenton of The Empire. Using what I refer to as ‘mobile practices', Coleman and Fenton found a middle ground between the conventional regimes of domestic femininity represented in many of the features of their woman's pages, and the emerging conditions of modern travel that allowed women to explore new places. Woman's pages and travel writing allowed the newspaper to contribute to nation-building in a multitude of ways and across a number of sites, such as the family, the city and countryside, Canada's colonial history and women's roles as the moral heads of household. In turn, mobile practices were both strategies for dealing with the emerging conditions of modernity as much as they were instruments for its continuation.
Coalition-Based Approaches for Addressing Environmental Issues in Childhood Asthma
Authors: Nicholas Elisa A. , Dwyer Maura , Murphy Amy , Taylor-Fishwick Judith C. , Cohn Jennifer H. , Kelly Cynthia S. , Gould Christine , Di Stefano Daeman
Published: April 2006

Outdoor air pollution and the indoor environment have been shown to cause or exacerbate childhood asthma. Allies Against Asthma coalitions implemented a broad range of activities to reduce or remediate indoor exposure to asthma environmental triggers for children with asthma including education and trigger remediation, physician and other health care provider education, and policy efforts to improve air quality in homes and schools. Outdoor environmental triggers were addressed through programs to increase education and awareness and efforts to change policies related to environmental conditions. Implementation of such efforts was complicated by the lack of safe and affordable housing and the amount of time and resources necessary to address policy change. Keys to success included promoting coordination and partnerships among coalition members, implementation of consistent messages, and building a broad and unified voice for policy change.
Improving Quality of Care and Promoting Health Care System Change: The Role of Community-Based Coalitions
Authors: Lara Marielena , Cabana Michael D. , Houle Christy R. , Krieger James W. , Lachance Laurie L. , Meurer John R. , Rosenthal Michael P. , Vega Ivonne
Published: April 2006

As part of their community action plans, the Allies Against Asthma coalitions have developed efforts to improve quality of care and promote health care system change. All the coalitions have used an interdisciplinary collaborative approach to design these strategies and demonstrated a range of intervention approaches appropriate to their local context and circumstances. The coalitions’ collective experience suggests that coalitions provide three key forces for quality improvement and change that may be lacking in the current fragmented U.S. health care system—motivation to change the status quo, integration across systems, and accountability for results. The collaborative and empowering processes that a coalition model encourages and the direct advocacy opportunity provided to the consumer appear to bring these forces into play.
Reality Check: Image Affects and Cultural Memory
Authors: Bronfen Elisabeth
Published: April 2006

elisabeth bronfen is Professor of English and American Studies at the University of Zurich. Her books include Home in Hollywood: The Imaginary Geography of Cinema (Columbia University Press, 2004), The Knotted Subject: Hysteria and Its Discontents (Princeton University Press, 1998), and Over Her Dead Body: Configurations of Femininity, Death, and the Aesthetic (Routledge, 1992). She is the coeditor, with Misha Kavka, of Feminist Consequences. Theory for the New Century (Columbia University Press, 2000). Currently, she is working on a cultural history of the night as well as a book on Hollywood war movies.
Socioeconomic Costs of Open Surgery and Gamma Knife Radiosurgery for Benign Cranial Base Tumors
Authors: Cho Der-Yang , Tsao Meilan , Lee Wen-Yuan , Chang Cheng-Siu
Published: April 2006

OBJECTIVE:

The aim of this study was to evaluate the relative socioeconomic costs of benign cranial base tumors treated with open surgery and gamma knife radiosurgery.

METHODS:

In a retrospective study, we studied 174 patients with benign cranial base tumors, less than 3 cm in diameter (or volume less than 30 ml), admitted in the past 5 years. Group A (n = 94) underwent open surgery for removal of the tumors, whereas Group B (n = 80) underwent gamma knife radiosurgery. The socioeconomic costs were evaluated by both direct and indirect cost. The direct costs comprised intensive care unit cost, ward cost, operating room cost, and outpatient visiting cost. The indirect costs included loss of workdays and mortality. The length of hospital stay, the number of lost workdays, surgical complications, mortality, and cost-effectiveness analysis were calculated as well. Student t test and χ2 test were used for statistical analysis.

RESULTS:

The mean length of hospital stay for open surgery was 18.2 ± 30.4 days including 5.0 ± 14.7 days of intensive care unit stay and 13.0 ± 15.2 days of ward stay, P<0.01. The mean hospital stay for gamma knife was 2.2 ± 0.9 days with no need of intensive care unit stay, P<0.01. The mean loss of workdays for open surgery was 160 ± 158 days and 8.0 ± 9.0 days for gamma knife, P<0.01. The gamma knife cost per hour (US $1435) is higher than the open surgery cost per hour (US $450), P<0.01. The direct cost for gamma knife (US $9677 ± $6700) is higher than that for open surgery (US $5837 ± $6587), P<0.01. Open surgery had more complication rates (31.2%) than gamma knife (3.8%). Open surgery had a mortality rate of 5.3%; there was no mortality for gamma knife. The indirect costs, including loss of workdays and mortality, were significantly higher for open surgery than for gamma knife, P<0.01. Finally, the socioeconomic cost (US $34,453 ± $97,277) is higher for open surgery than for gamma knife (US $10,044 ± $7481), P<0.01. The CEA is significantly higher in gamma knife (US $3762/quality-adjusted life year) than in open surgery (US $8996/quality-adjusted life year), P<0.01.

CONCLUSION:

Most of the socioeconomic loss with open surgery for benign cranial base tumors comes from the indirect costs of workdays lost and mortality. Gamma knife radiosurgery is a worthwhile treatment to our patients and to our society because it may shorten hospital stays and workdays lost and reduce complications, mortality, socioeconomic loss, and achieve better cost-effectiveness.
Minimally Invasive Lateral Mass Screw Fixation in the Cervical Spine: Initial Clinical Experience with Long-term Follow-up
Authors: Wang Michael Y. , Levi Allan D.O.
Published: April 2006

OBJECTIVE:

Lateral mass screw fixation of the subaxial cervical spine has been a major advancement for spinal surgeons. This technique provides excellent three-dimensional fixation from C3 to C7. However, exposure of the dorsal spinal musculature can produce significant postoperative neck pain. The incorporation of a minimal access approach using tubular dilator retractors can potentially overcome the drawbacks associated with the extensive muscle stripping needed for traditional surgical exposures.

METHODS:

A retrospective analysis was performed on the first 18 patients treated using lateral mass screws placed in a minimally invasive fashion. All patients, except 2 who were lost to follow-up, had a 2-year minimum clinical follow-up. All patients had a computed tomography (CT) scan in the immediate postoperative period to check the positioning of implanted hardware. Operative time, blood loss, and complications were ascertained. Fusion was assessed radiographically with dynamic radiographs and CT scans.

RESULTS:

Sixteen of the 18 patients underwent successful screw placement. Two patients had the minimal access procedure converted to an open surgery because radiographic visualization was not adequate in the lower cervical spine. Six cases involved unilateral instrumentation and 10 had bilateral screws. A total of 39 levels were instrumented. There were no intraoperative complications, and follow-up CT scans demonstrated no bony violations except in cases where bicortical purchase was achieved. All patients achieved bony fusion.

CONCLUSION:

A minimally invasive approach using tubular dilator retractors can be a safe and effective means for placing lateral mass screws in the subaxial cervical spine. Up to two levels can be treated in this manner. This approach preserves the integrity of the muscles and ligaments that maintain the posterior tension band of the cervical spine but requires adequate intraoperative imaging.
Suboptimal Sphenoid and Sellar Exposure: A Consistent Finding in Patients Treated with Repeat Transsphenoidal Surgery for Residual Endocrine-inactive Macroadenomas
Authors: Mattozo Carlos A. , Dusick Joshua R. , Esposito Felice , Mora Hugo , Cohan Pejman , Malkasian Dennis , Kelly Daniel F.
Published: April 2006

OBJECTIVE:

In a series of patients with residual endocrine-inactive macroadenomas who underwent repeat surgery, we assess possible reasons for prior subtotal removal, reoperative success, complication rates, and patient impressions.

METHODS:

All patients were identified who had a prior subtotal removal of an endocrine-inactive macroadenoma and were reoperated on for residual sellar tumor via an endonasal approach.

RESULTS:

Over 6 years, of 188 consecutive patients with endocrine-inactive adenomas, 30 (16%) had repeat surgery (age, 15–77 yr; median interval between surgeries, 25 mo; median follow-up, 20 mo). Maximal tumor diameter averaged 2.4 ± 0.9 cm. At reoperation, a suboptimal bony exposure was seen in all 30 patients: at the sphenoid keel, the sella, or both in 97, 93, and 90% of patients, respectively. Cavernous sinus invasion was seen in 16 (53%) patients and a fibrous/rubbery consistency in 12 (40%). Gross total tumor removal was achieved in 17 (57%) patients, including 12 of 14 (86%) with noninvasive tumors and 5 of 16 (31%) with invasive tumors, (P<0.01). All six fibrous/rubbery but noninvasive tumors were totally removed. Of 16 patients with preoperative visual loss, 15 (94%) improved. Complications included one each of cerebrospinal fluid leak, delayed sinusitis, and new hypothyroidism. In 17 patients with prior sublabial surgery who completed questionnaires, the second (endonasal) surgery was associated with an easier recovery, less pain, and better nasal airflow in 82, 88, and 93%, respectively (P<0.0001).

CONCLUSION:

In patients with residual sellar endocrine-inactive adenomas, a suboptimal opening at the sphenoid keel or sella at the first surgery and a high proportion of fibrous/rubbery tumors likely contributed to prior subtotal removal of otherwise accessible tumor. With a wider exposure, most noninvasive tumors can be totally removed, whereas invasive tumors can be effectively debulked. An endonasal reoperation is well tolerated with a low complication rate.
The Currarino Triad: Neurosurgical Considerations
Authors: Emans Pieter J. , van Aalst Jasper , van Heurn Ernest L.W. , Marcelis Carlo , Kootstra Gauke , Beets-Tan Regina G.H. , Vles Johannes S.H. , Beuls Emile A.M.
Published: April 2006

OBJECTIVES:

The Currarino triad, a relatively uncommon hereditary disorder, is often associated with tethered cord and anterior myelomeningocele. Little is known of the implications of these neuroanatomic malformations or of the neurosurgical attitude. The objective of this study is to identify the spinal cord and meningeal malformations associated with the Currarino triad and to discuss the risks and benefits of surgical intervention.

METHODS:

We analyzed the spinal cord malformations and the neurosurgical involvement with the Currarino triad by retrospective chart review.

RESULTS:

The Currarino triad neuroanatomic malformations were identified in five patients. The Currarino triad was associated with a tethered cord in three patients, a myelomeningocele in five patients, a syrinx in two patients, a fistula between the colon and spinal canal in two patients, and an Arnold-Chiari Type 1 malformation in one patient.

CONCLUSION:

Full spine imaging is required for all patients diagnosed with the Currarino triad. Magnetic resonance imaging of the head should be performed in every patient with neuroanatomic anomalies. Surgery of an anterior myelomeningocele is not necessarily indicated, only in the rare case in which the space-occupying aspect is expected to cause constipation or problems during pregnancy or delivery. Constipation directly after birth is seen in virtually all patients with the triad. Therefore, constipation cannot be used to diagnose a tethered cord syndrome nor indicate tethered cord release. Fistulas between the spinal canal and colon have to be operated on directly.
Duration of In Vivo Antimicrobial Activity of Antibiotic-impregnated Cerebrospinal Fluid Catheters
Authors: Pattavilakom Ananthababu , Kotasnas Despina , Korman Tony M. , Xenos Chris , Danks Andrew
Published: April 2006

OBJECTIVE:

Shunt infection is a major neurosurgical concern even after 50 years of experience with shunt surgery. Staphylococcus species are responsible for the majority of cerebrospinal fluid shunt infections. In vitro, antibiotic-impregnated cerebrospinal fluid shunt catheters (AIC) have demonstrated protection against multiple staphylococcus species and strains for reasonable periods. We aim to study the longevity of antimicrobial activity of AIC in vivo by using explanted catheters.

METHODS:

Twenty-five AICs (rifampicin [0.054%] and clindamycin [0.15%]) were explanted from 18 patients for noninfectious reasons, from 11 to 700 days postimplantation. The catheters were set up on standardized Staphylococcus aureus culture plates to detect antimicrobial activity. Unused fresh AIC segments were used as control in each culture plates.

RESULTS:

Fourteen explanted AICs demonstrated persistent antimicrobial activity against staphylococcal species. Antimicrobial activity was detected for a period of implantation up to 127 days. This is longer than that predicted by in vitro models.

CONCLUSION:

The persistent antimicrobial activity is likely to translate to ongoing in vivo antimicrobial protection. This period of protection exceeds that during which most shunt infections occur.
Ultrastructural Study of the Filum Terminale and Its Elastic Fibers
Authors: Fontes Ricardo B.V. , Saad Felippe , Soares Matheus S. , de Oliveira Flavia , Pinto Fernando C.G. , Liberti Edson A.
Published: April 2006

OBJECTIVE:

The filum terminale (FT) is a fibrovascular band involved in the pathophysiology of tethered cord syndrome (TCS). Its morphological and ultrastructural properties remain largely unknown even though they are thought to play a role in the generation of TCS in adult patients with normal level conus medullaris.

MATERIALS AND METHODS:

Twenty fresh adult human cadavers had their fila measured and removed. Transversal and longitudinal sections of the proximal, middle, and distal thirds of FT were submitted to light microscopy analysis with four different techniques. Five fila were selected for longitudinal and transversal scanning electron microscopy analysis.

RESULTS:

The bulk of the FT is composed of 5- to 20-μm thick longitudinal bundles of Type 1 collagen separated by 3- to 10-μm intervals, although capillaries and other elements may be present. A delicate (0.05–1.5 μm) meshwork of predominantly Type 3 collagen transversal fibers connects these bundles. Abundant longitudinally oriented elastic and elaunin fibers are found inside collagen bundles. A complex tridimensional structure is evidenced on electron microscopy.

CONCLUSION:

The longitudinal arrangement of collagen bundles and the impressive amount of elastic and elaunin fibers should elicit considerable elastic properties to the FT. An altered elasticity mechanism has been proposed for TCS; further studies are needed with TCS patients to define whether the collagen structure, Type 1/Type 3 proportion, or elastic fiber content are altered, which could lead to new histopathological definitions of TCS, helping neurosurgeons in the difficult management of TCS patients with normal level conus medullaris.
Fluorescence-responsive H2PO4− Receptor Based on Macrocyclic Boron Complex
Authors: Kameta Naohiro , Hiratani Kazuhisa
Published: April 2006

Macrocyclic boron complex showed selective fluorescence response toward H2PO4− via hydrogen-bond network, Lewis acid–base interaction, and inhibition of PET.
Targeted Advertising Strategies on Television
Authors: Gal-Or Esther , Gal-Or Mordechai , May Jerrold H. , Spangler William E.
Published: April 2006

The personal video recorder (PVR) facilitates the use of targeted advertising by allowing companies to monitor television viewing behavior and to build demographic profiles of viewers from the data that are collected. Our research explores the extent to which an advertiser should allocate resources to increase the quality of its targeting. We present a game-theoretic model that extends the conventional measurement of targeting quality by exploring the trade-off between two measures: accuracy and recognition. Accuracy measures the likelihood that any target segment prediction is correct, while recognition conversely measures the likelihood that any member of the target segment is identified. We find that the relative resources allocated to improving accuracy and recognition depend upon the size of the population of viewers, the propensity of viewers to skip commercials, the overall cost of airing commercials, and the competitive environment. Furthermore, the incentives to improve accuracy are markedly different from those to improve recognition. Although improving accuracy does not affect the extent of price competition, improving recognition leads to intensified price competition and reduced profitability in the product market. Thus, when facing a competitor that pursues a strategy to improve its recognition of potential customers, an advertiser should choose to reduce its investment in recognition and increase its investment in accuracy.
Party system change in Portugal, 19742005: the role of social, political and ideological factors
Authors: Freire Andr
Published: April 2006

The main goal of this article is to analyse the role of social, political and ideological factors in explaining party system change in Portugal during the democratic period (April 1974June 2005). We begin with the evolving trends in the party system format, and their main effects on the patterns of parties' interactions as well as on the functioning of the political system. This first approach will enable us to divide the democratic period into two distinct phases and an interlude. Following this, we will analyse the dimensions and strength of policy competition between the parties before, finally, analysing the impact of social, political and ideological factors on party system change in Portugal.
Diffusion approximations of Markov chains with two time scales and applications to population genetics, II
Authors: Ethier S. N. , Nagylaki Thomas
Published: April 2006

ForN =1, 2, …, let {(XN(k),YN(k)),k =0, 1, …} be a time-homogeneous Markov chain in. Suppose that, asymptotically asN → ∞, the ‘infinitesimal' covariances and means ofXN([·/εN]) areaij(x, y) andbi(x, y), and those ofYN([·/δN]) are 0 andcl(x, y). Assumeand limN→∞εN/δN= 0. Then, under a global asymptotic stability condition ondy/dt = c(x, y) or a related difference equation (and under some technical conditions), it is shown that (i)XN([·/εN]) converges weakly to a diffusion process with coefficientsaij(x, 0) andbi(x, 0) and (ii)YN([t/εN]) → 0 in probability for everyt> 0. The assumption in Ethier and Nagylaki (1980) that the processes are uniformly bounded is removed here.

The results are used to establish diffusion approximations of multiallelic one-locus stochastic models for mutation, selection, and random genetic drift in a finite, panmictic, diploid population. The emphasis is on rare, severely deleterious alleles. Models with multinomial sampling of genotypes in the monoecious, dioecious autosomal, andX-linked cases are analyzed, and an explicit formula for the stationary distribution of allelic frequencies is obtained.
Almost sure limit sets of random samples in ℝd
Authors: Davis Richard A. , Mulrow Edward , Resnick Sidney I.
Published: April 2006

If {Xj, } is a sequence of i.i.d. random vectors in , when do there exist scaling constants bn > 0 such that the sequence of random sets converges almost surely in the space of compact subsets of to a limit set? A multivariate regular variation condition on a properly defined distribution tail guarantees the almost sure convergence but without certain regularity conditions surprises can occur. When a density exists, an exponential form of regular variation plus some regularity guarantees the convergence.
A counterexample concerning the extremal index
Authors: Smith Richard L.
Published: April 2006

The concept of an extremal index, which is a measure of local dependence amongst the exceedances over a high threshold by a stationary sequence, has a natural interpretation as the reciprocal of mean cluster size. We exhibit a counterexample which shows that this interpretation is not necessarily correct.
Deterministic and stochastic epidemics with several kinds of susceptibles
Authors: Ball Frank
Published: April 2006

We consider the spread of a general epidemic amongst a population consisting of invididuals with differing susceptibilities to the disease. Deterministic and stochastic versions of the basic model are described and analysed. For both versions of the model we show that assuming a uniform susceptible population, with average susceptibility, leads to an increased spread of infection. We also show how our results can be extended to the carrier-borne epidemic model of Weiss (1965).
Multivariate dependent renewal processes
Authors: Slud Eric
Published: April 2006

A new class of reliability point-process models for dependent components is introduced. The dependence is expressed through a regression, following a form suggested by Cox (1972) for survival data analysis involving the current life-length of the components. After formulating the current-life process as a Markov process with stationary transitions and stating some general results on asymptotic behavior, we describe the stationary distributions in some bivariate examples. Finally, we discuss statistical inference for the new models, exhibiting and justifying full- and partial-likelihood methods for their analysis.
The distance between two random points in plane regions
Authors: Sheng T. K.
Published: April 2006

Let T be a triangle. P be a parallelogram, E be an ellipse, A, B be concentric circles, C, D be concentric dartboard regions, R, S be rectangles of the same orientation, U, V be two finite unions and/or differences of convex regions in the Euclidean plane. Given a function f on [0,∞), let E[/(r), U, V] denote the mean value of f(|u–v|), where |u–v| is the distance between u∊U and v∊V. Using Borel’s overlap technique, a specific distance weight function and a specific equivalence relation, we obtain formulae expressing E[f(r), U, V] in terms of triple integrals, expressing E(rn, U, V), E[f(r), A, V] and E[f(r), R, V] in terms of double integrals, expressing E[f(r), A, B], E[f(r), R, S], E[f(r), T, T], E[f(r), P, P], E(rn, C, D) and E(rn, R, V) in terms of single integrals, and expressing E(rn, R, S), E(rn, P, P), E(rn, T, T), E(rn, E, E) in terms of elementary functions, where n is an integer ≧−1. Many other related results are also given.
ARMA processes have maximal entropy among time series with prescribed autocovariances and impulse responses
Authors: Franke Jürgen
Published: April 2006

The maximum-entropy approach to the estimation of the spectral density of a time series has become quite popular during the last decade. It is closely related to the fact that an autoregressive process of order p has maximal entropy among all time series sharing the same autocovariances up to lag p. We give a natural generalization of this result by proving that a mixed autoregressive-moving-average process (ARMA process) of order (p, q) has maximal entropy among all time series sharing the same autocovariances up to lag p and the same impulse response coefficients up to lag q. The latter may be estimated from a finite record of the time series, for example by using a method proposed by Bhansali (1976). By the way, we give a result on the existence of ARMA processes with prescribed autocovariances up to lag p and impulse response coefficients up to lag q.
Analysis of a counting process associated with a semi-Markov process: number of entries into a subset of state space
Authors: Masuda Yasushi , Sumita Ushio
Published: April 2006

Let N(t) be a finite semi-Markov process on 𝒩 and let X(t) be the associated age process. Of interest is the counting process M(t) for transitions of the semi-Markov process from a subset G of 𝒩 to another subset B where 𝒩 = B ∪ G and B ∩ G = ∅. By studying the trivariate process Y(t) =[N(t), M(t), X(t)] in its state space, new transform results are derived. By taking M(t) as a marginal process of Y(t), the Laplace transform generating function of M(t) is then obtained. Furthermore, this result is recaptured in the context of first-passage times of the semi-Markov process, providing a simple probabilistic interpretation. The asymptotic behavior of the moments of M(t) as t → ∞ is also discussed. In particular, an asymptotic expansion for E[M(t)] and the limit for Var [M(t)]/t as t → ∞ are given explicitly.
On some time-non-homogeneous diffusion approximations to queueing systems
Authors: Giorno V. , Nobile A. G. , Ricciardi L. M.
Published: April 2006

Time-non-homogeneous diffusion approximations to single server–single queue–FCFS discipline systems are considered. Under various assumptions on the nature of the time-dependent functions appearing in the infinitesimal moments the transient and the regime behaviour of the approximating diffusions are analysed in some detail. Special attention is then given to the study of a diffusion approximation characterized by a linear drift and by a periodically time-varying infinitesimal variance. Unlike the behaviour of transition functions and moments, the p.d.f. of the busy period is seen to be unaffected by the presence of such periodicity.
On a unified approach to the analysis of two-sided cumulative sum control schemes with headstarts
Authors: Yashchin Emmanuel
Published: April 2006

The necessary and sufficient conditions for various modes of interactions of the upper and lower schemes with headstarts are derived. The expression for the Laplace transform of the run-length distribution (for both interacting and non-interacting schemes) is obtained and used to develop a method of analysis for general two-sided cumulative sum schemes with headstarts. The results are shown to be relevant in the case when the schemes are supplemented by Shewhart’s control limits.
Phase transition in one-dimensional random walk with partially reflecting boundaries
Authors: Percus Ora E.
Published: April 2006

We consider an asymmetric random walk, with one or two boundaries, on a one-dimensional lattice. At the boundaries, the walker is either absorbed (with probability 1–ρ) or reflects back to the system (with probability p).

The probability distribution (Pn(m)) of being at position m after n steps is obtained, as well as the mean number of steps before absorption. In the one-boundary case, several qualitatively different asymptotic forms of Pn(m) result, depending on the relationship between transition probability and the reflection probability.
Exact distributions for shapes of random triangles in convex sets
Authors: Kendall D. G.
Published: April 2006

The paper starts with a simple direct proof that . A new formula is given for the shape-density for a triangle whose vertices are i.i.d.-uniform in a compact convex set K, and an exact evaluation of that shape-density is obtained when K is a circular disk. An (x, y)-diagram for an auxiliary shape-density is then introduced. When K = circular disk, it is shown that is virtually constant over a substantial region adjacent to the relevant section of the collinearity locus, large enough to contain the work-space for most collinearity studies, and particularly appropriate when the ‘strip’ method is used to assess near-collinearity.
Macroscopic properties of a linear mosaic
Authors: Hall Peter
Published: April 2006

A linear mosaic is a process of random line segments distributed according to a Poisson process. This paper presents a wide-ranging treatment of limit theory for the two major macroscopic properties of a linear mosaic: total vacancy, and total number of spacings (or clumps). These quantities do not admit an explicit, exact treatment, and are perhaps most informatively studied by means of limit theory. We permit segment length to have a general distribution, and study the implications of tail properties of this distribution. Necessary and sufficient conditions are given for vacancy on an interval [0, t] to admit a normal approximation as t →∞. An approximate formula is provided for the probability of complete coverage, in the case of general segment length distribution. In all cases, properties of vacancy and number of spacings are studied together, by means of joint limit theorems, rather than individually, as in some earlier work.
On the independence of sojourn times in tandem queues
Authors: Chen Thomas M.
Published: April 2006

Reich (1957) proved that the sojourn times in two tandem queues are independent when the first queue is M/M /1 and the second has exponential service times. When service times in the first queue are not exponential, it has been generally expected that the sojourn times are not independent. A proof for the case of deterministic service times in the first queue is offered here.
A survey of stepping-stone models in population dynamics
Authors: Renshaw Eric
Published: April 2006

A survey is presented of stochastic and deterministic developments in the study of the effects of nearest-neighbour ‘migration’ between spatially separated ‘colonies’. Such processes are of general applicability, and are relevant to any vector processX(t) = (X1(t), · ··,XN(t)) in which the arrival, departure and transfer rates for the states {X(t) = n} may be written in the formαi(ni), βi(ni) andγij(ni,nj), respectively, wheren =(n1,· ··, nN). Whilst the main body of results are described in terms of birth-death, genetic and epidemic situations, the final section examines within colony interaction in the context of spatial predator-prey processes.
Calculation of sensitivities of throughputs and realization probabilities in closed queueing networks with finite buffer capacities
Authors: Cao Xi-Ren
Published: April 2006

Perturbation analysis is an efficient approach to estimating the sensitivities of the performance measures of a queueing network. A new notion, called the realization probability, provides an alternative way of calculating the sensitivity of the system throughput with respect to mean service times in closed Jackson networks with single class customers and single server nodes (Cao (1987a)). This paper extends the above results to systems with finite buffer sizes. It is proved that in an indecomposable network with finite buffer sizes a perturbation will, with probability 1, be realized or lost. For systems in which no server can directly block more than one server simultaneously, the elasticity of the expected throughput can be expressed in terms of the steady state probability and the realization probability in a simple manner. The elasticity of the throughput when each customer’s service time changes by the same amount can also be calculated. These results provide some theoretical background for perturbation analysis and clarify some important issues in this area.
A note on the independence and total dependence of max i.d. distributions
Authors: Hüsler J.
Published: April 2006

We show that the simple characterizations given by Takahashi for the independence and the total dependence of a multivariate extreme value distribution do not hold for the larger class of maximum infinitely divisible (max i.d.) distributions. This holds also for sup self-decomposable distributions.
On a generalization of the preemptive resume priority
Authors: Nain Philippe
Published: April 2006

This paper considers a queueing system with two classes of customers and a single server, where the service policy is of threshold type. As soon as the amount of work required by the class 1 customers is greater than a fixed threshold, the class 1 customers get the server's attention; otherwise the class 2 customers have the priority. Service interruptions can occur for both classes of customers on the basis of the above description of the service mechanism, and in this case the service interruption discipline is preemptive resume priority (PRP). This model, which turns out to be a generalization of the PRP queueing system, has potential applications in computer systems and in communication networks. For Poisson inputs, exponential (arbitrary) servicetime distribution for class 1 (class 2) customers, we derive the Laplace–Stieltjes transform of the stationary joint distribution of the workload of the server, by reducing the analysis to the resolution of a boundary value problem. Explicit formulas are obtained.
Moments for first-passage and last-exit times, the minimum, and related quantities for random walks with positive drift
Authors: Janson Svante
Published: April 2006

Consider the sequence of partial sums of a sequence of i.i.d. random variables with positive expectation.

We study various random quantities defined by the sequence of partial sums, e.g. the time at which the first or last crossing of a given level occurs, the value of the partial sum immediately before or after the crossing, the minimum of all partial sums. Necessary and sufficient conditions are given for the existence of moments of these quantities.
A method of approximating Markov jump processes
Authors: Crank Keith N. , Puri Prem S.
Published: April 2006

We present a method of approximating Markov jump processes which was used by Fuhrmann [7] in a special case. We generalize the method and prove weak convergence results under mild assumptions. In addition we obtain bounds on the rates of convergence of the probabilities at arbitrary fixed times. The technique is demonstrated using a state-dependent branching process as an example.