bluuebunny/crossref_metadata_2025 huggingface dataset:
Using Patterns in Track‐Plate Footprints to Identify Individual Fishers
Authors: HERZOG CARL J. , KAYS ROLAND W. , RAY JUSTINA C. , GOMPPER MATTHEW E. , ZIELINSKI WILLIAM J. , HIGGINS RICHARD , TYMESON MIKE
Published: May 2007

Abstract: If individuals can be identified from patterns in their footprints, noninvasive survey methods can be used to estimate abundance. Track plates capture fine detail in the footprints of fishers (Martes pennanti), recording rows of dots corresponding to tiny papillae on the animal's metacarpal pad. We show that the pattern of these dots can be used to identify individual fishers, similar to human fingerprints. A probabilistic model of uniqueness based on variation in spacing between 1,400 pairs of dots that we measured in prints of 14 different fisher feet suggests the probability of encountering a similar pattern in the print of a different foot by chance alone is ≤ 0.35n, where n = the number of dot pairs examined. This predicts a 0.00003 probability that a match made using 10 pairs of dots is false. Dot spacing from footprints made by the same foot was remarkably consistent (sN = 0.02 mm, n = 24 dot pairs). Combined, these results suggest dot patterns in fisher footprints were unique to individuals and were consistently reproduced on track plates. Empirical tests of matching accuracy were best with good‐quality prints, highlighting the need for experience judging when prints are usable. We applied print matching to fisher detections collected on track plates deployed at 500‐m intervals along 10 3.5‐km transects in the Adirondack region of New York, USA. Of 62 fisher detections, 85% had ≥ 1 footprint of suitable quality to compare with other high‐quality prints. We found that most detections from a transect were from the same individual fisher suggesting nonindependence of detections. Thus, data from traditional track‐plate deployments over small time periods cannot be used as a measure of abundance, but new study designs using print matching could obtain robust noninvasive, mark—recapture density estimates.
Mesial Migration Effect on Root Morphology of Mandibular Third Molars
Authors: Bıçakçı A. Altuğ , Sökücü Oral , Babacan Hasan , Köşger H. Hüseyin
Published: May 2007

Objective: To test the hypothesis that there is a relationship between forward mandibular third molar migration and root curvature of the mandibular third molars.

Materials and Methods: The study is comprised of 64 patients who had a history of unilateral mandibular first molar extraction before 16 years of age with no other missing teeth or prosthetic restorations in the mandible. The extraction space was fully or partly closed. The mean remaining space was 1.1 ± 0.41 mm. The root angles for the mesial and distal roots of the mandibular third molars were measured on the panoramic radiographs by calculating the differences between the angle formed by the long axis drawn perpendicular to the occlusal plane of the crown of mandibular third molar and the central line of the lower one ninth of the root through the root apex. The differences between the extracted and nonextracted sides for mesial and distal roots were analyzed using a paired sample t-test.

Results: Both mesial and distal roots were approximately 8° more vertical on the extraction sides than on the nonextraction sides. The differences were statistically significant.

Conclusion: Mesial tooth migration of mandibular third molars reduces the amount of root curvature developing on this tooth.
Mandibular Cervical Headgear vs Rapid Maxillary Expander and Facemask for Orthopedic Treatment of Class III Malocclusion
Authors: Baccetti Tiziano , Rey Diego , Angel David , Oberti Giovanni , McNamara James A.
Published: May 2007

Objective: To compare the effectiveness of the rapid maxillary expander and facemask (RME/ FM) and mandibular cervical headgear (MCH) protocols when followed by fixed appliances and evaluated at a postpubertal observation in patients with dentoskeletal Class III malocclusion.

Materials and Methods: The sample treated with the RME/FM followed by fixed appliances included 32 patients (12 boys and 20 girls). The sample treated with the MCH followed by fixed appliances included 26 patients (eight boys and 18 girls). Cephalometric analysis was performed at T1 (before treatment) and T2 (after the first phase of orthopedic therapy and the second phase of fixed appliances). T1-T2 changes were evaluated by means of t-tests.

Results: Midfacial length, mandibular length, and the sagittal position of the chin all showed significantly smaller increases in the MCH group than in the RME/FM group. The amount of increase in the overjet was also significantly smaller in the MCH group, whereas the amount of molar correction was greater. The upper incisors were significantly less proclined and the lower incisors were significantly less retroclined in the MCH group when compared with the RME/FM group.

Conclusions: RME/FM therapy appears to be indicated in Class III patients with a component of maxillary retrusion, whereas MCH therapy is preferable in patients with mandibular prognathism.
Dynamic MRI Evaluation of Tongue Posture and Deglutitive Movements in a Surgically Corrected Open Bite
Authors: Karacay Seniz , Akin Erol , Ortakoglu Kerim , Bengi A. Osman
Published: May 2007

Tongue thrust usually develops in the presence of anterior open bite in order to achieve anterior valve function. In the literature, tongue thrust is described both as the result and the cause of open bite. If it is an adaptation to malocclusion, then tongue posture and deglutitive tongue movements should change after treatment. In this case report, an adult who had skeletal open bite and Class II malocclusion caused by mandibular retrusion was treated surgically. The mandible was advanced in a forward and upward direction with a sagittal split osteotomy. The open bite and Class II malocclusion were corrected and an increase in the posterior airway space (PAS) was observed. Pretreatment and posttreatment dynamic magnetic resonance imaging (MRI) revealed that tongue tip was retruded behind the incisors and contact of the tongue with the palate increased. It was also determined that the anterior and middle portions descended, whereas the posterior portion was elevated at all stages. Advancement of the mandible, correction of open bite, and an increase in PAS affected not only the tongue posture and deglutitive movements, but also the breathing pattern of the patient.
Mandibular First Molar Relation to Variable Lower Face Skeletal Components
Authors: Andria Louis Matthew , Leite Luis Paulo , Dunlap April M. , Cooper Emily C. , King Lydia Buxbaum
Published: May 2007

Objective: To evaluate the position of the mandibular first permanent molar in the mandible relative to several factors.

Materials and Methods: A total of 185 untreated Class I and Class II patients were randomly selected from a sample of 350 patients from a single office. The palatal and mandibular planes were related to Frankfort horizontal to create the interjaw or “B” angle. Age and the mesial contact of the mandibular first molars were used. The landmarks were projected at right angles to the Frankfort horizontal for effective mandibular dimension lengths. Actual-length dimensions were projected at right angles to the mandibular plane. Pearson product moment correlation coefficients were computed to evaluate the effect of age, cranial length, and mandibular contribution to the molar's sagittal position in the mandible. Significance was reported only when P < .05 to determine a 95% confidence level.

Results: Statistically significant positive correlations indicated that the mandibular molar is located more forward with increasing age, longer mandibular body length, and increasing posterior facial height. In contrast, significant negative correlations to the interjaw, mandibular plane, ramal inclination angles, and the linear ramal contribution corresponded to a more posterior position of the molar with increasing angles.

Conclusions: The mandibular first permanent molar is located more anteriorly with an older patient, a longer mandibular body, greater posterior facial height, and an acute interjaw angle. In contrast, an increase in the forward tip of the ramus places the molar in a more posterior location.
The Influence of National Business Environment as Shaper of Organizatinoal Action: The Case of Argentina
Authors: Hatum Andrés
Published: May 2007

Organizational studies have often omitted the importance of national differences as shapers of the organizational action of firms. This study aims to address the particular national features that distinguish the Argentinean national context from others. To do so, we introduce a multidimensional framework that includes both institutional and cultural elements. In so doing, we were able to begin to answer the following questions: To what extent have the unique characteristics of the national context shaped indigenous businesses in Argentina? And, how have the national business characteristics affected the way indigenous businesses organize themselves, transform, and respond under competitive pressures? The result of the analysis shows the importance of three major aspects in understanding organizational action: the role of the state, the role of financial institutions, and the role of national culture as shapers of organizational action.
Portuguese Management Between Global Rhetoric and Local Reality: The Case of Human Resource Management
Authors: Cabral‐Cardoso Carlos
Published: May 2007

Although the gap between rhetoric and reality is not a specific human resource management (HRM) feature, the disconnection between discourse and action seems to have reached unusual stages in this case. Not much is known about HRM in Portugal, but it is clear that Portuguese academics and practitioners have extensively adopted the global HRM rhetoric. With an environment apparently unfavorable to the HRM normative model, this paper examines the ways in which global HRM rhetoric meets Portuguese reality.
Student victimization by school staff in the context of an Israeli national school safety campaign
Authors: Khoury‐Kassabri Mona , Astor Ron Avi , Benbenishty Rami
Published: May 2007

In this study, we examined and compared findings from four nationally representative studies of victimization of students by school staff in Israel. We explored whether levels of student victimization by school staff (teachers, principals, secretaries, janitors, etc.) have changed between 1998, 1999, 2002, and 2005, and whether patterns of group differences (gender, age, and cultural groups) were replicated across those four points in time. We employed representative samples stratified by ethnic affiliation and school levels. In 1998, there were 15,916 4th–11th grade students from 232 schools; in 1999, 16,414 4th–11th grade students from 239 schools; in 2002, 21,577 4th–11th grade students from 410 schools and in 2005, 27,316 4th–11th grade students from 526 schools across Israel. Overall, the results reveal that for the entire student population in Israel reports of victimization are quite similar across the four waves of data collection. Levels of physical victimization were consistently higher among boys and Arab students, but other group differences were less consistent, especially with regard to differences between age groups. Aggr. Behav. 34:1–8, 2008. © 2007 Wiley‐Liss, Inc.
Psychopathy and behavioral correlates of victim injury in serious juvenile offenders
Authors: Vitacco Michael J. , Caldwell Michael F. , Van Rybroek Gregory J. , Gabel Jason
Published: May 2007

The study examines delinquent behavior and psychopathy and assesses their relationship to victim injury in a population of 168 incarcerated juvenile delinquent males with lengthy histories of criminal and violent behavior. A series of multiple regressions found that 17% of the variance associated with level of victim injury was accounted for by a model that included the three‐factor model of the Psychopathy Checklist: Youth Version [Forth, Kosson, and Hare, 2003], criminal versatility, and age of onset of criminal offending. Notably, anger and DSM‐IV symptoms of conduct disorder were not related to level of victim injury. The results of this study support an escalation hypothesis where individuals with earlier onset to criminal behavior and greater criminal versatility escalate to more severe violence. The current results demonstrate the importance of integrating established theories of juvenile delinquency when explaining severe violence in youth. Aggr. Behav. 33:537–544, 2007. © 2007 Wiley‐Liss, Inc.
Actuator fault isolation and reconfiguration in transport‐reaction processes
Authors: El‐Farra Nael H. , Ghantasala Sathyendra
Published: May 2007

A methodology is presented for the design of integrated, model‐based fault diagnosis and reconfigurable control systems for transport‐reaction processes modeled by nonlinear parabolic partial differential equations (PDEs) with control constraints and actuator faults. The methodology brings together nonlinear feedback control, fault detection and isolation (FDI), and performance‐based supervisory switching between multiple actuator configurations. Using an approximate, finite‐dimensional model that captures the PDE's dominant dynamic modes, a stabilizing nonlinear feedback controller is initially designed for each actuator configuration, and its stability region is explicitly characterized in terms of the control constraints and actuator locations. To facilitate the fault diagnosis task, the locations of the control actuators are chosen in a way that ensures that the evolution of each dominant mode, in appropriately chosen coordinates, is excited by only one actuator. Then, a set of dedicated FDI filters, each replicating the fault‐free behavior of a given state of the approximate system, are constructed. The choice of actuator locations ensures that the residual of each filter is sensitive to faults in only one actuator and decoupled from the rest, thus, allowing complete fault isolation. Finally, a set of switching rules are derived to orchestrate switching from the faulty actuators to healthy fallbacks in a way that preserves closed‐loop stability and minimizes the closed‐loop performance deterioration resulting from actuator faults. Precise FDI thresholds and control reconfiguration criteria that account for model reduction errors are derived to prevent false alarms when the reduced order model‐based fault‐tolerant control structure is implemented on the process. A singular perturbation formulation is used to link these thresholds with the degree of separation between the slow and fast eigenvalues of the spatial differential operator. The developed methodology is successfully applied to the problem of constrained, actuator fault‐tolerant stabilization of an unstable steady‐state of a representative diffusion‐reaction process. © 2007 American Institute of Chemical Engineers AIChE J, 2007
Extended robust model predictive control of integrating systems
Authors: González Alejandro H. , Marchetti Jacinto L. , Odloak Darci
Published: May 2007

The robust model predictive control (MPC) of systems with stable and integrating modes is addressed. The approach proposed here extends the method presented in Odloak in 2004 that can only be applied to open‐loop stable systems. Here, the robust controller is developed assuming that there is model uncertainty in both stable and integrating parts of the system. The method considers a modified cost function that turns the infinite output horizon MPC globally convergent for any finite input horizon. The controller is based on a modified version of the state‐space model utilized by Carrapiço and Odloak in 2005 to develop a nominally stable MPC for systems with stable and integrating modes. The approach considers the inclusion of feasible cost contracting constraints in the control optimization problem, taking into account the annulment of the integrating modes to assure a bounded infinite horizon cost. A simulation example is included to illustrate the performance and robustness of the proposed approach and to demonstrate that the controller can be implemented in real applications. © 2007 American Institute of Chemical Engineers AIChE J, 2007
Angulated femurs and the skeletal dysplasias: Experience of the International Skeletal Dysplasia Registry (1988–2006)
Authors: Alanay Yasemin , Krakow Deborah , Rimoin David L. , Lachman Ralph S.
Published: May 2007

Angulated or bent femur (isolated or associated with other long bone bowing) in the fetus or newborn is relatively common when evaluating patients with skeletal dysplasias. To determine the extent and heterogeneity of disorders associated with angulated or bent femurs, we analyzed cases in the radiographic database (1998–2006) of the International Skeletal Dysplasia Registry (ISDR) and determined which established skeletal dysplasias and genetic syndromes are associated with this finding. The results show that more than 40 distinct disorders with varying frequency (very rare to more commonly occuring disorders) can be associated with bowed/bent/angulated femurs. Sixty‐six percent of the cases with angulated femurs belonged to three well described groups of disorders; campomelic disorders (24.4%), thanatophoric dysplasia (23.9%) and osteogenesis imperfecta (OI) (18.1%). With specific emphasis on these, this cross‐sectional cohort provides discussion of data on other rare disorders associated with angulated femurs and the importance of the finding relative to its occurrence within a diagnostic group. This study aims to provide differential diagnosis of entities to be considered when a fetus or newborn is found to have congenital bowing/angulation of the femur. © 2007 Wiley‐Liss, Inc.
Microcephaly with chorioretinopathy in a brother–sister pair: Evidence for germ line mosaicism and further delineation of the ocular phenotype
Authors: Trzupek Karmen M. , Falk Rena E. , Demer Joseph L. , Weleber Richard G.
Published: May 2007

Microcephaly with chorioretinopathy (OMIM 156590) is an autosomal dominant syndrome, characterized primarily by chorioretinal lesions and microcephaly. The phenotype is variable, and has been described in association with retinal dysplasia that can be stable or show progressive degeneration, retinal folds, lymphedema, and mental retardation. We describe two siblings with microcephaly, mental retardation, and variable retinal and choroidal abnormalities. Patient 1 has multiple atrophic and dysplastic‐appearing lesions of the retina and choroid in each eye. An ERG at 5 months of age disclosed markedly subnormal scotopic and photopic responses with delayed flicker timing. Patient 2 has bilateral macular folds with vitreoretinopathy, serous retinal detachments, glaucoma, and cataracts OU. Both have mental retardation with hypotonia and severe microcephaly. Chorioretinopathy and retinal folds have been described independently in microcephaly with chorioretinopathy. The present sibs are the first in whom these features are observed while the parents are normal. Our findings support an expansion of the ocular phenotype and suggest the existence of germ line mosaicism. © 2007 Wiley‐Liss, Inc.
Recurrent interstitial deletions of proximal 18q: A new syndrome involving expressive speech delay
Authors: Cody Jannine D. , Sebold Courtney , Malik Amtul , Heard Patricia , Carter Erika , Crandall AnaLisa , Soileau Bridgette , Semrud‐Clikeman Margaret , Cody Catherine M. , Hardies L. Jean , Li Jinqi , Lancaster Jack , Fox Peter T. , Stratton Robert F. , Perry Brian , Hale Daniel E.
Published: May 2007

Most deletions of the long arm of chromosome 18 involve some part of the most distal 30 Mb. We have identified five individuals with cytogenetically diagnosed interstitial deletions that are all proximal to this commonly deleted region. The extent of their deletions was characterized using molecular and molecular cytogenetic techniques. Each participant was assessed under the comprehensive clinical evaluation protocol of the Chromosome 18 Clinical Research Center. Three of the five individuals were found to have apparently identical interstitial deletions between positions of 37.5 and 42.5 Mb (18q12.3 → 18q21.1). One individual's deletion was much larger and extended from a more proximal breakpoint position of 23 Mb (18q11.2) to a more distal breakpoint at 43 Mb (18q21.1). The fifth individual had a proximal breakpoint identical to the other three, but a distal breakpoint at 43.5 Mb (18q21.1). The clinical findings were of interest because the three individuals with the smaller deletions lacked major anomalies. All five individuals were developmentally delayed; however, the discrepancy between their expressive and receptive language abilities was striking, with expressive language being much more severely affected. This leads us to hypothesize that there are genes in this region of chromosome 18 that are specific to the neural and motor planning domains necessary for speech. Additionally, this may represent a previously underappreciated syndrome since these children do not have the typical clinical abnormalities that would lead to a chromosome analysis. © 2007 Wiley‐Liss, Inc.
Absence of PITX2, BARX1, and FOXC1 mutations in De Hauwere syndrome (Axenfeld–Rieger anomaly, hydrocephaly, hearing loss): A 25‐year follow up
Authors: Lowry R. Brian , Gould Douglas B. , Walter Michael A. , Savage Paul R.
Published: May 2007

This study reports a 25‐year follow‐up of a patient with De Hauwere syndrome (Axenfeld–Rieger anomaly, hydrocephalus, and hearing loss) whose intelligence is normal. Short stature and hyperlaxity of joints later leading to severe joint pain were noted. Mutation analysis of candidate genes known or suspected to be associated with Axenfeld–Rieger eye malformations was performed. This included complete sequencing for PITX2, BARX1 and the forkhead domain of FOXC1. The results of these analyses were negative and suggest that De Hauwere syndrome is caused by a different gene. © 2007 Wiley‐Liss, Inc.
Report of a fourth individual with a lethal syndrome of choanal atresia, athelia, evidence of renal tubulopathy, and family history of neck cysts
Authors: Horvath Gabriella A. , Armstrong Linlea
Published: May 2007

In 1998, Hisama et al. described three brothers born following pregnancies complicated by oligohydramnios in the second or third trimester. Post‐natal renal functions were compromised, and post‐mortem studies showed kidney tissue abnormalities. Resuscitation and support were required, and they survived 25 hr to 12 days. All boys had a similar craniofacial appearance with infraorbital creases, low set dysplastic ears, as well as athelia, and broad digits with small nails. Variably present features were choanal atresia, preauricular tags and pits, branchial clefts, ventricular septal defect, type IIB interrupted aortic arch, pulmonary lobation anomaly, absent gallbladder, absent thymus, absent parathyroid gland, accessory spleen, and imperforate anus. Their mother, maternal grandmother, and maternal first cousin had neck cysts removed as children. We describe a female infant born following a pregnancy where oligohydramnios developed between 27 and 33 weeks gestation. Renal function was initially impaired, but improved over the first weeks of life. There was however a persistent renal wasting of magnesium. Her craniofacial appearance with infraorbital creases and low set dysplastic ears was similar to the brothers' described by Hisama et al. [1998; Am J Med Genet 80:335–342]. She had choanal atresia, athelia, a preauricular pit, gingival cysts, broad digits with small nails, right aortic arch with a vascular ring, hypothyroidism, impaired glucose homeostasis, hypoadrenalism, neurological impairment, and brain calcifications on CT. She died after 13 weeks of intensive care. Her mother as a child and maternal grandfather as an adult had neck cysts removed. The similarities between the cases suggest a common syndrome. © 2007 Wiley‐Liss, Inc.
Inbreeding depression in non‐human primates: a historical review of methods used and empirical data
Authors: Charpentier M.J.E. , Widdig A. , Alberts S.C.
Published: May 2007

Offspring born to related parents may show reduced fitness due to inbreeding depression. Although evidence of inbreeding depression has accumulated for a variety of taxa during the past two decades, such analyses remain rare for primate species, probably because of their long generation time. However, inbreeding can have important fitness costs and is likely to shape life‐history traits in all living species. As a consequence, selection should have favored inbreeding avoidance via sex‐biased dispersal, extra‐group paternity, or kin discrimination. In this paper, we review empirical studies on the effects of inbreeding on fitness traits or fitness correlates in primate species. In addition, we report the methods that have been used to detect inbreeding in primate populations, and their development with the improvement of laboratory techniques. We focus particularly on the advantages and disadvantages using microsatellite loci to detect inbreeding. Although the genetic data that are typically available (partial pedigrees, use of microsatellite heterozygosity as an estimate of genomewide inbreeding) tend to impose constraints on analyses, we encourage primatologists to explore the potential effects of inbreeding if they have access to even partial pedigrees or genetic information. Such studies are important because of both the value of basic research in inbreeding depression in the wild and the conservation issues associated with inbreeding, particularly in threatened species, which include more than half of the currently living primate species. Am. J. Primatol. 69:1370–1386, 2007. © 2007 Wiley‐Liss, Inc.
The effects of RF absorbers on exposure levels at 100 MHz
Authors: Allen Stewart J , Mylacraine Kevin S.
Published: May 2007

The study presented in this article was designed to complete a dosimetry protocol required to establish the RF exposure levels at 100 MHz for measurement of the effect on cognition in human volunteers near the resonant frequency in seated positions. The results are compared with those reported previously using the same experimental procedures, except with the vertically radiating dipole antenna and corner reflector raised by .30 m to the vertical center of the anechoic chamber. The average whole body SAR for the high and low SAR conditions used in the previous study was achieved with a 12% increase in transmitter forward power. However, the incident power density averaged over the body was increased by 42%, from 40 and 80 W/m2 in the previous study to 57 and 113 W/m2 in the current study to achieve the same whole body average SAR used in the previous study. The differences in field patterns and field intensities between the previous and current studies were introduced by interactions between the E‐field and RF absorbers in the floor and ceiling, which represent resonant structures at 100 MHz. Bioelectromagnetics 28:406–408, 2007. © 2007 Wiley‐Liss, Inc.
Assessing the numerical accuracy of the impedance method
Authors: Olree Kenneth S. , Horch Kenneth W.
Published: May 2007

The impedance method has been used extensively to calculate induced electric fields and currents in tissue as a result of applied electromagnetic fields. However, there has previously been no known method for an a priori assessment of the numerical accuracy of the results found by this method. Here, we present a method which permits an a priori assessment of the numerical accuracy of the impedance method applied to physiologically meaningful problems in bioengineering. The assessment method relies on estimating the condition number associated with the impedance matrix for problems with varying shapes, sizes, conductivities, anisotropies, and implementation strategies. Equations have been provided which predict the number of significant figures lost due to poor matrix conditioning as a function of these variables. The results show that, for problems of moderate size and uncomplicated geometry, applied fields should be measured or calculated accurately to at least five or six significant figures. As resolutions are increased and material properties are more widely divergent even more significant figures are needed. The equations provided here should ensure that solutions found from the impedance method are calculated accurately. Bioelectromagnetics 28:454–462, 2007. © 2007 Wiley‐Liss, Inc.
Does direction of induced electric field or current provide a test of mechanism involved in nerve regeneration?
Authors: Greenebaum B. , Sisken Betty F.
Published: May 2007

We suggest an experimental comparison of two directions for applying the time‐varying magnetic fields which have been found to speed spontaneous regeneration of injured peripheral nerves and in attempts to repair spinal cord injuries. Time‐varying magnetic fields induce currents in a plane perpendicular to the magnetic field direction. The lower conductivity of the spinal cord's sheath (dura matter) or of the myelin sheath of peripheral nerves would seem to confine the induced electric fields and currents to the spinal cord or nerve itself. The proposed comparison could allow choosing between two possible modes of action of the fields: (1) Magnetically‐induced electric fields or currents may be encouraging ion flow or otherwise helping enzyme, channel or other interactions at the cell membrane, as is thought to be the case in field stimulation of healing in bone. This mechanism should be independent of field direction. (2) Work in developing organisms and with fields applied to nerve cells in vitro has shown that neurite growth is guided parallel to both endogenous and external electric fields. This mechanism would be effective when induced electric fields are parallel, but not when they are perpendicular to the nerve. Any experimental test should seek to produce as close as possible to the same induced current intensity with both field directions. Possible confounding factors, as well as breakdowns in the assumptions of the simple model presented here, would have to be considered. This proposal was motivated by a recent report in which the authors listed a changed field direction as one of several possible reasons for an unsuccessful experiment. Bioelectromagnetics 28:488–492, 2007. © 2007 Wiley‐Liss, Inc.
Dominant factors influencing whole‐body average SAR due to far‐field exposure in whole‐body resonance frequency and GHz regions
Authors: Hirata Akimasa , Kodera Sachiko , Wang Jianqing , Fujiwara Osamu
Published: May 2007

Electromagnetic (EM) absorption of the human body for far‐field exposure at the International Commission on Non‐Ionizing Radiation Protection (ICNIRP) reference level has two peaks in the resonance frequency and GHz regions. Dominant factors influencing whole‐body average specific absorption rate (SAR) in these two frequency regions have not yet been revealed sufficiently. The main purpose of this study is to clarify the dominant factors influencing EM power absorption in terms of whole‐body average SAR in an anatomically based model compared with those in a homogeneous anthropomorphic model and corresponding cuboid models. Computational results show that EM absorption peak in the resonance frequency region greatly depends on the electric properties of tissue, while the peak in the GHz region is affected mainly by the surface area of the model. Bioelectromagnetics 28:484–487, 2007. © 2007 Wiley‐Liss, Inc.
Efficiency of a Two‐Stage Procedure for Survival Studies
Authors: Flandre Philippe
Published: May 2007

A two‐stage procedure using occurrences of a surrogate endpoint regarding a true clinical endpoint has been proposed (FLANDRE, O'QUIGLEY and BROOKMEYER, 1994). The procedure allows estimation of the survival function S(t) reliably and comparison of treatment groups. The aim of this paper is to investigate the efficiency of such a two‐stage procedure compared to a one stage procedure, i.e. a classical study. The efficiency is estimated by the ratio of the standard derivation of S(t) for the classical procedure to the standard derivation of S(t) for the two‐stage procedure and represents the precision on the estimation of S(t). Standard deviation of S(t) is approximate by the delta‐method. Using the exponential model. some numerical results are presented.
Confidence Intervals on Linear Combinations of K Variances
Authors: Anbupalam T. , Ponnuswamy K. N. , Srinivasan M. R.
Published: May 2007

TING et al. (1990) have proposed a method of constructing approximate confidence intervals on linear combinations of several variances that are unrestricted in sign. In this article we have proposed modifications of their method. The performances of the proposed modifications are examined using a computer simulation.
A Nonparametrical Evaluation of Anova and MANOVA Designs Using Interaction Structure Analysis
Authors: Stemmler Mark
Published: May 2007

The interaction structure analysis (ISA) is proposed as a nonparametric procedure for the evaluation of uni‐ and multivariate analysis of variance models. Main effects and interactions of (independent) treatment variables are replaced by interaction‐types where types are defined as those treatment‐response combinations which occur significantly more often than expected under a null hypothesis (Ho) of no treatment effects. The application of ISA and the typological interpretation of ISA results are illustrated for an ANOVA design from toxicology and for a MANOVA design from psychopharmacology.
Biplots in Reduced‐Rank Regression
Authors: Braak Cajo J. F. Ter , Looman Caspar W. N.
Published: May 2007

Regression problems with a number of related response variables are typically analyzed by separate multiple regressions. This paper shows how these regressions can be visualized jointly in a biplot based on reduced‐rank regression. Reduced‐rank regression combines multiple regression and principal components analysis and can therefore be carried out with standard statistical packages. The proposed biplot highlights the major aspects of the regressions by displaying the least‐squares approximation of fitted values, regression coefficients and associatedt‐ratios. The utility and interpretation of the reduced‐rank regression biplot is demonstrated with an example using public health data that were previously analyzed by separate multiple regressions.
A Weighted Nonparametric Procedure for the Combination of Independent Events
Authors: Koziol James A. , Tuckwell Henry C.
Published: May 2007

A weighted inverse normal procedure for combining independent events is considered. The procedure is utilized to combine results from six clinical studies on homovanillic acid concentrations in relation to the hypothesis that schizophrenia is the result of dopaminergic hyperactivity.
Evaluation and Estimation of Various Markov Models with Applications to Membrane Channel Kinetics
Authors: Pulford G. W. , Gallant J. C. , Kennedy R. A. , Chung S. H.
Published: May 2007

Hidden Markov modelling is a powerful and efficient digital signal processing strategy for extracting the maximum likelihood model from a finite length sample of noisy data. Assuming the number of states in the model is known, then the state levels, transition probabilities, initial state distribution and the noise variance can be estimated. We investigate the applicability of this technique in membrane channel kinetics not only as a parameter estimator, but also as an aid to discriminating between various model types according to their statistical likelihood. We survey three representative classes of channel dynamics, namely: aggregated Markov models, semi‐Markov models (with asymptotically convergent transition probabilities), and coupled Markov models; reformulating each within a discrete‐time hidden Markov model framework. We then provide numerical evidence of the effectiveness of the procedure using simulated channel data and hence show that the correct model, as well as the model parameters, can be discerned. We also demonstrate that the model likelihood can be used to indicate the approximate number of states in the model.
Efficiency Indices for Second‐Order Designs
Authors: Jensen D. R.
Published: May 2007

Design efficiencies are studied for inferences regarding the coefficients of second‐order models. Subspaces of parameters are identified wherein each of two designs dominates the other locally, or the two designs are equally efficient. Both Fisher efficiency in estimation and Pitman efficiency in hypothesis testing are considered. Eight small second‐order designs ink=3 regressor variables are screened using a four‐part efficiency index. Of these, the central composite, Box‐Behnken, small composite, and hybrid H310 and H311 B designs are found to be generally superior and roughly comparable. Detailed comparisons among these five designs are then undertaken. This work provides further tools for use in design evaluation, requiring only basic matrix operations independently of experimental data.
The Structure of Compounded Trivariate Binomial Distributions
Authors: Papageorgiou H. , David Katerina M.
Published: May 2007

A family of trivariate binomial mixtures with respect to their exponent parameter is introduced and its structure is studied by the use of probability generating functions. Expressions for probabilities, factorial moments and factorial cumulants are given. Conditional distributions are also examined. Illustrative examples include the trivariate Poisson, binomial, negative binomial and modified logarithmic series distributions. In addition, properties of the compounded trivariate Poisson distribution are discussed. Finally biological, medical and ecological applications are indicated.
A Bivariate Discrete Charlier Series Distribution
Authors: Papageorgiou H. , Loukas S. , Loukas S.
Published: May 2007

A bivariate distribution is introduced with marginals convolutions of a binomial and a Poisson random variables. Various properties of the distribution are examined. Estimation is discussed and illustrated by fitting the distribution to two sets of data. An application to ornithology is also indicated.
Estimation of Variance Components Based on Partial Triallel Mating Design
Authors: Srinivasan M. R. , Ponnuswamy K. N.
Published: May 2007

The higher order mating designs like triallel and double crosses have been found to be useful in exploiting the epistatic gene action. However, it is equally important to note that enormous amount of resources are necessary to develop triallel crosses even for a small number of genetic lines p as it involves developing p(p—1)(p—2)/2 distinct three way hybrids. A simple answer to this problem is to consider a sample of triallel crosses known as partial triallel crosses (PTC) which retains the salient properties of triallel crosses at less cost. In this paper we consider the estimation of variance components (design and genetic) based on partial triallel mating designs.
Characterization of the Negative Binomial and Gamma Distributions
Authors: Ong S. H.
Published: May 2007

Characterization of the negative binomial and gamma distributions by a conditional distribution and a linear regression, and the gamma distribution by the negative binomial distribution are given. An application to a random shock model is discussed.
Distribution‐free Partially Sequential Tests for Treatments Versus Control Setting
Authors: Kim Dongjae , Wolfe Douglas A.
Published: May 2007

In this paper we propose a class of distribution‐free tests for the treatments versus control setting using the partially sequential sampling technique. Expressions for the asymptotic distributions and power for the tests are provided and criteria for adapting a particular test to have asymptotic power restrictions against alternatives of interest are discussed. Comparative results of a Monte Carlo power study are also presented.
Approximate Confidence Intervals for Contrasts in the Balanced Three Factor Mixed Model
Authors: Mosier Michael C. , Graybill Franklin A.
Published: May 2007

When conducting a statistical analysis of data from a designed experiment, an investigator is often interested in confidence intervals for contrasts of the fixed effects. If the analysis involves a mixed linear model, exact confidence intervals for contrasts of the fixed effects are not always available. In such cases, confidence intervals with approximate coverage probabilities must be used.

As will be shown, this problem may be generalized to that of constructing a confidence interval for the parameter μ, where X is a normal random variable with mean μ and variance ∑ aqθq, where a1…,aQ are known constants, Uq = nqS/θq is a chi‐squared random variable with nq degrees of freedom, for each q = 1,…, Q, and X,U1,…, UQ are mutually independent. In this paper, we consider the case where Q = 3 and a3 ≤0.
Confidence Limits for the Ratio of Two Binomial Proportions Based on Likelihood Scores: Non‐Iterative Method
Authors: Nam Jun‐Mo
Published: May 2007

The interval estimation of the ratio of two binomial proportions based on the score statistic is superior over other methods. Iterative algorithms for calculating the approximate confidence interval have been provided by, e.g., KOOPMAN (1984, Biometrics 40:513–517) and GART and NAM (1988a, Biometrics 44:323–338). This note presents the analytical solutions for upper and lower confidence limits in a closed form and gives examples for numerical illustration. The non‐iterative method is generally more desirable than the iterative method.
On Testing for Equicorrelation in Random Coefficient Models
Authors: Bhatti M. I. , Barry A. M.
Published: May 2007

Recently BHATTI (1993) considered an efficient estimation of random coefficient model based on survey data. The main objective of this paper is to construct one sided test for testing equicorrelation coefficient in presence of random coefficients using optimal testing procedure. The test statistic is a ratio of quadratic forms in normal variables which is most powerful and point optimal invariant.
Analysis of Bacterial Spatial Patterns at the Initial Stage of Biofilm Formation
Authors: Hamilton M. A. , Johnson K. R. , Camper A. K. , Stoodley P. , Harkin G. J. , Gillis R. J. , Shope P. A.
Published: May 2007

Using sophisticated microscopy techniques, we observed the spatial pattern of bacteria colonizing a sterile 316L stainless steel coupon as bulk water containing bacteria flowed across the coupon. The experiments used stainless steel of differing roughness and surface chemistry. The ultimate goal was to identify surface features which influence bacterial adsorption. The immediate statistical goal was to distinguish patterns consistent with complete spatial randomness from patterns showing regularity or aggregation. This goal was accomplished by using modified analyses of distance functions commonly applied in field ecology. The method protected against a potential multiple comparisons problem. For the null value of the distance function, we calculated tolerance envelopes such that the tolerance level was simultaneous for all distances of concern. Computer simulation experiments showed that the nominal level was accurate. The methodology was effective for detecting and describing patterns of colonization known not to be completely spatially random.
A New Model of Aging: Specific Versions and Their Application
Authors: Yakovlev Andrej Yu , Tsodikov Alexandr D. , Anisimov Vladimir N.
Published: May 2007

This paper is concerned with some versions of a stochastic model of aging proposed recently by TYURIN et al. (1993). In contrast to the commonly used Gompertz‐Makeham approach, the model yields a bounded hazard rate, thereby providing a better description of survival of old individuals in a population. Depending on plausible biological assumptions to be tested, only a few special cases of the basic model appear to be useful in experimental data analysis. We report the results of their application to experimental data on animal longevity obtained in a follow‐up study. When interpreted in terms of the model parameters, the data suggest drastically dissimilar patterns of aging for female versus male rats.
A Bayesian Decision Procedure for Selecting Prognostic Variables Associated with Survival for Data in which Censoring is Prevalent
Authors: Fraser Martin D. , Bartolucci Alfred A. , Smith William A. , Singh Karen P.
Published: May 2007

A Bayesian procedure is developed for the selection of concomitant variables in survival models. The variables are selected in a step‐up procedure according to the criterion of maximum expected likelihood, where the expectation is over the prior parameter space. Prior knowledge of the influence of these covariates on patient prognosis is incorporated into the analysis. The step‐up procedure is stopped when the Bayes factor in favor of omitting the variable selected in a particular step exceeds a specified value. The resulting model with the selected variables is fitted using Bayes estimates of the coefficients. This technique is applied to Hodgkin's disease data from a large Cooperative Clinical Trial Group and the results are compared to the results from the classical likelihood selection procedure.
Heterogeneous Variances in Repeated Measures
Authors: Wu Yuan , McGilchrist C. A.
Published: May 2007

A general approach to repeated measures analysis described in MCGILCHRIST and CULLIS (1991) is extended to general linear models in which there is a homogeneous correlation structure such as a stationary process but the variances are heterogeneous over time. Models for the variance heterogeneity are suggested and results are applied to data examining the effect of enzootic pneumonia on young pigs.
A Measure to Evaluate the Closeness of Satterthwaite's Approximation
Authors: Khuri André I.
Published: May 2007

Satterthwaite's approximation of the distribution of a nonnegative linear combination of independent mean squares is addressed in this article. A measure is developed to quantify the closeness of this approximation by using certain optimization results given by THIBAUDEAU and STYAN (1985). The main advantage of the proposed measure is to provide a theoretical framework for determining conditions under which Satterthwaite's approximation may be inadequate. This is demonstrated in three examples portraying frequently encountered problems in analysis of variance.
On the Estimation of True Treatment Response when Patients Enter Staggeredly in a Clinical Trial
Authors: Biswas S. , Chitkara Sunita
Published: May 2007

Due to staggered entries of patients during a clinical trial, the available exposure to observe the patients under a treatment is less and non‐uniform while the patients with whom the trial is started initially are exposed to uniform exposures to the treatment. Because of this, the true response of the treatment gets masked. Here we have attempted to estimate the true response of the treatment in presence of staggered entries. Further, by Martingale approach the probability of acceptance/rejection has been worked out for both staggered and no staggered entry cases. The results are then compared with the help of a numerical example which shows that under staggered entries the treatment is rejected with higher probability.
Three Multiple Comparison Procedures for Trimmed Means
Authors: Wilcox Rand
Published: May 2007

Two common goals when choosing a method for performing all pairwise comparisons of J independent groups are controlling experiment wise Type I error and maximizing power. Typically groups are compared in terms of their means, but it has been known for over 30 years that the power of these methods becomes highly unsatisfactory under slight departures from normality toward heavy‐tailed distributions. An approach to this problem, well‐known in the statistical literature, is to replace the sample mean with a measure of location having a standard error that is relatively unaffected by heavy tails and outliers. One possibility is to use the trimmed mean. This paper describes three such multiple comparison procedures and compares them to two methods for comparing means.