bluuebunny/crossref_metadata_2025 huggingface dataset:
Growth in pups of the subantarctic fur seal (Arctocephalus tropicalis) on Amsterdam Island
Authors: Guinet C. , Georges J.‐Y.
Published: February 2006

Growth in body mass in pups of the subantarctic fur seal Arctocephalus tropicalis was studied at Amsterdam Island, southern Indian Ocean during the rearing period between December 1995 and August 1996. We examined the change in the rates of mass gain and mass loss with pup age to explain the overall change in mass throughout the rearing period, when mothers alternate foraging trips at sea and attendance periods ashore. In the absence of their mothers, pups fast and lose mass. During the maternal attendance period ashore pups suck and gain mass. There was no significant difference in the rate of growth in mass between male and female pups. The rate of loss in mass during a fasting event was positively related to the initial body mass but negatively related to the age and duration of the fast of the pup. The rate of mass loss was best related to pup age by a quadratic relationship. The rate of mass loss increased until pups were 120 days old and then decreased until the end of the study period. The rate of gain in mass following a maternal foraging trip was positively related to the initial pup mass but negatively related to the foraging trip duration, and we found that the rate of mass gain decreased linearly with the age of the pup. The concomitant decrease in the rate of mass loss and mass gain for pups > 120 days old allowed pups to maintain a positive growth until they were 220 days old. After 220 days of age the rate of mass loss exceeded the rate of mass gain and the pups start to lose mass until weaning.
The relationship of neonate mass and incubation temperature to embryonic development time in a range of animal taxa
Authors: Gillooly J. F. , Dodson S. I.
Published: February 2006

Embryonic development time has been of long‐standing interest to physiologists and ecologists because of its importance in understanding the behaviour and ecology of reproduction, and the evolution of reproductive strategies in animals. Yet, the relationship of embryonic development time to both neonate mass and incubation temperature remains poorly understood for most taxonomic groups. Here we define the relationship of embryonic development time to neonate mass (embryo mass at birth) and incubation temperature for a broad range of animals, ectothermic and endothermic, invertebrate and vertebrate, microscopic and gigantic. We begin by establishing the relationship of embryonic development time to neonate mass for a broad array of zooplankton, fishes and amphibians for temperatures from 5 to 20°C. Next, we compare the relationships of embryonic development time to neonate mass in these aquatic ectotherms to those for terrestrial ectotherms (reptiles) and endotherms (birds and mammals) in terms of degree‐days. The similar nature of these relationships allows us to define embryonic development time as a function of neonate mass for many of the species considered here with a single equation in terms of degree‐days for incubation temperatures ranging from 5 to 38°C. This relationship establishes a basis by which to compare differences in embryonic development time among species.
Roost selection by noctules (Nyctalus noctula) and Daubenton's bats (Myotis daubentonii)
Authors: Boonman Martijn
Published: February 2006

Roost selection by tree roosting noctules Nyctalus noctula and Daubenton's bats Myotis daubentonii was determined by comparing roost characteristics with the characteristics of randomly chosen tree cavities in the area. The following parameters were determined for 81 noctule roosts and 27 Daubenton's bat roosts: tree species, type of cavity (woodpecker or natural), entrance height, compass direction of entrance and distance to the edge of the wood. Roost choice of both bat species was similar except that Daubenton's bats used woodpecker cavities less than noctules. Both bat species were selective in their roost choice. Daubenton's bats preferred oaks over beeches, and noctules preferred woodpecker cavities over natural cavities, indicating dependence on woodpeckers. Both bat species preferred to roost close to the edge of the wood. Roosting close to the edge of the wood may reduce commuting flight costs for both species or may be preferable for thermoregulatory reasons.
Individual recognition in the Damaraland mole‐rat, Cryptomys damarensis (Rodentia: Bathyergidae)
Authors: Jacobs D. S. , Kuiper S.
Published: February 2006

Conspecific recognition was investigated in the eusocial and subterranean Damaraland mole‐rat Cryptomys damarensis. This species out‐breeds and is xenophobic. Differences in the frequency of agonistic behaviours between male–male pairs were used as an indication of recognition. Focal males were tested with familiar, unfamiliar, and foreign conspecifics. Males directed significantly more aggression towards unfamiliar colony mates and foreign conspecifics than towards familiar colony mates. This happened even though both focal and test animals retained contact with their natal colonies and, therefore, any group cue. Furthermore, when male–male pairs were returned to their natal colonies they continued directing aggression towards each other but not towards the rest of the colony. These results suggest that the Damaraland mole‐rat uses individually distinct cues rather than kin‐specific cues based on genetic relatedness.
Female‐initiated copulations in two tetragnathid spiders from Indonesia: Leucauge nigrovittata and Tylorida ventralis
Authors: Preston‐Mafham Kenneth G. , Cahill Alexis
Published: February 2006

The mating behaviour of two species of spiders in their natural habitat is described. A male Leucauge nigrovittata from Sumatra mated repeatedly with a newly‐moulted adult female which he had been guarding. Each copulation was in response to a body‐jerking ‘invitation’ display by the female. In Tylorida ventralis from Sulawesi, males and females copulated almost continuously from dawn until dusk over several days. Females switched from diurnal to nocturnal web construction during this time. After temporary separations, females were almost as likely as males to solicit the re‐initiation of copulation. In both species the sexes are of approximately equal size. The possible adaptive reasons for the extended mating times in T. ventralis are discussed.
Feeding ecology, density and biomass of the freshwater turtle,Phrynops geoffroanus, inhabiting a polluted urban river in south‐eastern Brazil
Authors: Souza Franco Leandro , Abe Augusto Shinya
Published: February 2006

This study examines the ecology of a population of Geoffroy's side‐necked turtlePhrynops geoffroanusinhabiting a polluted urban river in Ribeirão Preto city, São Paulo state, south‐eastern Brazil. Adult turtles fed mainly on Chironomidae larvae and pupae (Chironomuscf.plumosus, 100% of occurrence frequency) and domestic waste, but they also consumed terrestrial items (cockroach, snails) and carrion. Juvenile turtles showed more feeding diversity than the adults and exhibited a trend for predation on Chironomidae pupae, but this is not reflected in resource partitioning. The elevated number of turtles (170–230 turtles/ha of river) and biomass (255–345 kg/ha of river) inhabiting this urban river is probably the result of the abundance of sewage and organic waste produced by humans, the absence of predators, and increased availability of nesting areas. Such factors convert this area into an environment highly advantageous for the survival of Geoffroy's side‐necked turtle.
Mate locating strategies of the green carpenter bees Xylocopa (Lestis) aeratus and X. (L.) bombylans
Authors: Leys Remko
Published: February 2006

This paper describes the mate locating strategies of male Australian carpenter bees Xylocopa (Lestis) aeratus Smith and X.(L.) bombylans (F.). Males of X. aeratus display three different mate locating strategies: (1) non‐territorial patrolling near nests or flowers; (2) territorial defence of nests that contain unmated females; (3) non‐resource territoriality (hill‐topping). At the onset of the mating season, non‐territorial patrolling and territorial defence of nests were observed in three out of four populations that were studied, while in a fourth population only non‐resource territoriality was observed. Later in the mating season both territorial defence of nests and non‐resource territoriality were observed in one of the populations. Male X. bombylans have only been observed using the non‐resource territoriality. Males of all size classes used the same strategy at any one time, but males that were observed more than once in a territory were significantly larger, suggesting that larger males have greater territory‐holding capacity. Upon encountering males, receptive female X. aeratus alternated low zigzag flights through the vegetation with high‐velocity flights well above the vegetation, while males followed closely. This behaviour is interpreted as a test of the flight capacity of males, and is indicative of pronounced female choice. The mate locating strategies of the two species are compared with literature data from other xylocopine bees, and factors that might affect the choice of a particular mate locating strategy are briefly discussed.
Epigenetic dental variability of Israeli hares (Lepussp.): ecogenetic or phylogenetic causation?
Authors: Suchentrunk F. , Alkon P. U. , Willing R. , Yom‐Tov Y.
Published: February 2006

We examined 3747 teeth from 134 hares (Lepussp.) collected at 46 sites in Israel to test whether variation in epigenetic occlusal characters was linked to ecogenetic or phylogenetic factors. Collection sites encompassed a wide range of ecogeographical and climatic regimes. We compared data from Israeli hares with occlusal characters of 160 cape haresL. capensisfrom East Africa and 68 brown haresL. europaeusfrom central Europe. Only three teeth (I1, I2, M3) did not show occlusal variation. Thirty‐eight occlusal characters were derived from dental variants by dichotomous (0/1) scoring. Absence of association of character states among characters of single teeth indicated a lack of morphotypes. Epigenetic differentiation among hares from northern, central and southern Israel, and the two East African, and two central European samples, was revealed by pairwise C. A. B. Smith's ‘mean measures of divergence’ (MMD), based on frequencies of character states. Cluster analyses of MMD values revealed little epigenetic differentiation between northern and southern Israeli hares, but greater differentiation between central European and East African hares. Concordance of the MMD matrix with linear geographical distances among sampling regions was demonstrated by a Mantel test. No frequencies of character states exhibited significant changes across the climatic parameters among hares from northern and southern Israel. But the individual folding index, which expresses the degree of enamel on the occlusal surface, slightly decreased from north to south. Our results support a phylogenetic interpretation of occlusal character variation. Despite distinct differences in external appearance, hares from northern and southern Israel probably comprise a single species that encompasses two closely related geographical populations with a probable area of overlap. Israeli hares are intermediate between European brown hares and East African cape hares, with a slightly closer relationship to the cape hares.
Hybridization and changes in the distribution of Iceland gulls (Larus glaucoides/kumlieni/thayeri
Authors: Weir D. N. , Kitchener A. C. , McGowan R. Y.
Published: February 2006

Three Iceland gull taxa were defined mainly from adult wingtip melanism. Up until about 1860, nominateglaucoides(no melanism) was known to breed from Greenland to western High Arctic Canada, but by about 1900 it was essentially confined to Greenland. Until 1860,thayeri(most melanism) was known only from western High Arctic Canada, but from 1900 to 1980 it was found throughout High Arctic Canada and in a small part of north‐west Greenland. At high latitudes in Canada it replacedglaucoides, with which it was formerly sympatric in the west and probably interbred. The first knownkumlieni(intermediate, variable melanism) were from west Greenland in the 1840s, and by 1900 the western and northern limits of most of its breeding range in the eastern Canadian Low/High Arctic were known. The range ofkumlienilies between those ofthayeriandglaucoidesand overlaps both;kumlienibred in Greenland by 1964. It freely interbreeds withthayeriand probably withglaucoides. Winter ranges ofglaucoidesandthayerihave changed little since they were first determined forglaucoidesby 1860 and forthayeriby the 1920s. However, winter adultkumlieniwas unknown from Greenland to the British Isles until 1900; there were a few records prior to 1915 and progressively more after 1950. The study adds to the evidence thatkumlienirepresents introgressive hybridization by westernthayeriinto easternglaucoides.

D. N. Weir died 15 August 2000.
Biased distribution of trematode metacercariae in the nephric system of Rana tadpoles
Authors: Thiemann Greg W. , Wassersug Richard J.
Published: February 2006

Echinostoma sp. use larval anurans as intermediate hosts. The cercariae enter the tadpoles via the cloacal opening and form metacercarial cysts in the kidneys, pronephroi, and Wolffian ducts. To examine the distribution of Echinostoma metacercariae in Rana sylvatica and Rana clamitans tadpoles, 200 individuals of each species were exposed to free‐swimming cercariae. There was a significant left:right bias in the distribution of metacercariae within both R. sylvatica and R. clamitans tadpole hosts, with trematodes preferentially encysting in nephric structures on the right side. In R. sylvatica and R. clamitans, respectively, 56.7% and 96.8% of the metacercariae were on the tadpoles' right side. Asymmetry in the distribution of parasites followed the direction of the asymmetry in tadpole kidney size, but was much greater. Trematodes preferentially encysted in the head kidneys of R. clamitans, which regress at metamorphosis. The right head kidney was the most commonly infected structure in R. clamitans tadpoles, containing 72.7% of all cysts in that species. Despite the preference of trematodes to encyst in the head kidney, there was no correlation between the number of cysts in the right kidney and the number in the right head kidney. This suggests that limited space in the head kidney does not influence metacercarial formation in the kidney proper. The high frequency of unilateral encystment in both anurans, and in the head kidneys of R. clamitans, may be the result of a co‐evolved relationship that ultimately benefits both the host and parasite by ensuring host survival.
P300 amplitude as an indicator of externalizing in adolescent males
Authors: Patrick Christopher J. , Bernat Edward M. , Malone Stephen M. , Iacono William G. , Krueger Robert F. , McGue Matt
Published: February 2006

Reduced P300 amplitude is reliably found in individuals with a personal or family history of alcohol problems. However, alcoholism is part of a broader externalizing spectrum that includes other substance use and antisocial disorders. We hypothesized that reduced P300 is an indicator of the common factor that underlies disorders within this spectrum. Community males (N=969) were assessed at age 17 in a visual oddball task. Externalizing was defined as the common factor underlying symptoms of alcohol dependence, drug dependence, nicotine dependence, conduct disorder, and adult antisocial behavior. A robust association was found between reduced P300 amplitude and the externalizing factor, and this relation accounted for links between specific externalizing disorders and P300. Our findings indicate that reduced P300 amplitude is an indicator of the broad neurobiological vulnerability that underlies disorders within the externalizing spectrum.
‘Virtual’ intimacies? Families communicating across transnational contexts
Authors: WILDING RAELENE
Published: February 2006

Abstract
Many analyses of the uses of Information and Communication Technology (ICT) focus on factors such as gender, class and communication infrastructures in explaining how and whether people communicate across distance. In this article, I argue that such analyses fail to capture the full complexity of ICT use. I use the results of a large qualitative study of transnational families, conducted in Australia, Ireland, Italy, the Netherlands, Iran, Singapore and New Zealand, to examine how and whether kin maintain contact across time and space. The research demonstrates that ICTs are more available for some people than for others. However, also and possibly more important in the decisions people make about using particular communication technologies are the social and cultural contexts of family life, which render some ICTs more desirable than others at specific points in time. Acknowledging this provides an important corrective to economic analyses of transnationalism, and contributes to theorizing and documenting the role of ICTs in the maintenance of transnational social networks.
Transnational dimensions of the digital divide among Salvadoran immigrants in the Washington DC metropolitan area
Authors: BENÍTEZ JOSÉ LUIS
Published: February 2006

Abstract
In this article I explore some dimensions of digital divide among Salvadoran immigrants in the Washington DC metropolitan area. Three main issues are addressed: the configuration of social networks, local axes of inequality and the transnational forms of appropriation and usage of the Internet and other Information and Communication Technologies (ICTs). Based on a media ethnography approach, the analysis combines structuration theory with diasporic media studies. It includes an examination of Internet communications, Salvadoran diasporic websites, the use of mobile phones and teleconferencing, and the transnational dimensions of the digital divide. The study's findings include the limited accessibility to the Internet and ICTs among Salvadoran immigrants, the importance of understanding the transnational dimensions of the digital divide (particularly in terms of generation) and the need to design and implement communication and technology policies in the Salvadoran transnational society.
Testing the usability of information technology applications with learners with special educational needs (SEN)
Authors: Williams Peter , Nicholas David
Published: March 2006

This paper reports on the ‘usability’ element of a study examining the development of a multimedia Learning Environment (LE) for Special Educational Needs (SEN) students, designed to match learner requirements to learning materials, as elicited from cognitive and accessibility profiles drawn up by teachers and learning support assistants. In developing the system, the researchers examined how usability tests could be undertaken that meaningfully involved people with cognitive disabilities. Methods were developed following interviews with staff and much observation of lessons involving the use of computers. The usability tests themselves consisted of a series of graded activities drawn from various SEN sources. They required only one or two actions – activating a mouse and/or guiding a cursor – for completion. The study highlighted a number of issues inherent in working with a user group comprising SEN students, including interpreting non‐compliance and other behaviour patterns, making tasks meaningful, and accounting for the presence and degree of assistance given by a helper. Of particular interest was the issue of matching the intellectual level of tasks with the physical ease‐of‐use of the system. The paper suggests various methods for obviating problems elicited, and makes recommendations for the further development of computer‐based activities designed to promote independent learning and inclusivity.
Student teachers and cultural diversity in an Australian regional university
Authors: Hope‐Rowe Gaelene
Published: March 2006

This article examines student teachers’ discursive constructions of difference, cultural diversity and race as they write and talk about their cultures and identities in relation to teaching and learning in the first year of a Primary Teaching Degree in a regional Australian university.

The qualitative case study which informs this paper considered the discursive resources that students bring to teacher education from their past experiences and contact with cultural differences in communities, families and schools. It examined various discourses around cultural diversity that are available to them in the teacher education course and how their discursive practices are mediated and reconstructed in the particular university context. A major goal was to explore how universities in largely homogeneous settings might firstly work with the resources that students bring to teacher education and, secondly, assist students to consider the implications of cultural and linguistic diversity for teaching language and literacy.
Obtaining Unbiased Estimates of Tagging SNP Performance
Authors: Iles M. M.
Published: March 2006

The use of tagging SNPs (tSNPs) as a cost‐effective means of capturing genetic diversity is widespread. However, the quality of the tSNPs selected is dependent on the initial sample in which they are characterized. If the initial marker set is too sparse the tSNPs chosen will capture less information than a naïve analysis suggests. A simple method has been proposed that should provide a better estimate of the performance of tSNPs. It is shown here that this approach is both unbiased and accurate, even for small numbers of typed markers. The effect of unknown phase is also investigated and it is shown that, excepting very small samples, this has little effect on the accuracy of the method.
Histomorphologic Characterization of Noncarious and Caries‐Affected Dentin/Adhesive Interfaces
Authors: Haj‐Ali Reem , Walker Mary , Williams Karen , Wang Yong , Spencer Paulette
Published: March 2006

Purpose
: The purpose of this study was to compare the dentin/adhesive interfacial characteristics when bonding to noncarious as well as caries‐affected dentin.

Materials and Methods
: Seven extracted, unerupted, third molars were sectioned into halves. Artificial caries was created on one‐half of each tooth, leaving the other half as a control. Dentin surfaces were treated with UNO adhesive according to the manufacturer's instructions for the wet‐bonding technique and under environmental conditions present in the oral cavity. Dentin/adhesive interface sections of each half‐tooth were stained with Goldner's trichrome, a classic bone stain, and examined using light microscopy. The width of exposed collagen was measured directly from photomicrographs, and adhesive penetration was analyzed qualitatively.

Results:
The degree and extent to which the adhesive encapsulated the demineralized dentin matrix were reflected in the color difference in the stained sections with the noncarious dentin sections showing a degree of collagen encapsulation superior to that of the caries‐affected dentin sections. The overall mean widths of exposed collagen were significantly (p≤ .05) greater at the caries‐affected dentin/adhesive interface, 8.6 (1.7) μm, as compared with those at the noncarious dentin/adhesive interface, 6.0 (1.5) μm.

Conclusions:
The morphologic characteristics of the caries‐affected dentin/interface suggest an increase in the exposed collagen zone and a decrease in the quality of the adhesive infiltration when compared with noncarious dentin. The evidence suggests that dentin substrate characteristics have a significant effect on the dentin/adhesive interface structure.
The Effect of Gingival Retraction Procedures on Periodontal Indices and Crevicular Fluid Cytokine Levels: A Pilot Study
Authors: Feng Jian , Aboyoussef Hoda , Weiner Saul , Singh Surendra , Jandinski John
Published: March 2006

Purpose: The purpose of this study was to examine the effects of placement of retraction cord subgingivally upon periodontal indices including plaque index (PI), gingival index (GI), pocket depth (PD), bleeding on probing (BOP), and attachment level (AL), as well as gingival crevicular fluid (GCF) and TNF‐α levels.

Methods: Ten teeth in 6 patients who were periodontally healthy were selected. These teeth had pocket depths of 3 mm or less, no evidence of significant loss of attachment, BOP, or plaque accumulation. The patients each received an oral prophylaxis. The following week, baseline measurements of periodontal indices and TNF‐α were taken and the retraction cord was placed for 15 minutes. Following removal, the patients were dismissed. The periodontal indices measured included PI, GI, PD, BOP, and AL. In addition, the levels of TNF‐α in GCF, were investigated. These measurements were made before gingival retraction as a baseline and on the 1st, 3rd, 7th, 14th, and 28th days post retraction.

Results: A repeated measures ANOVA showed that TNF‐α levels in GCF were significantly increased at all five intervals after gingival retraction compared to the baseline. The mean TNF‐α level peaked at Day 1 (0.90 ± 0.62), then declined at Days 3 (0.53 ± 0.16), 7 (0.43 ± 0.08), 14 (0.47 ± 0.10), and 28 (0.43 ± 0.08) but was still elevated 54% above baseline at Day 28, p < 0.01. The GI was significantly elevated at Day 1 (0.9 ± 0.49), p < 0.01; Day 3 (0.53 ± 0.32); and Day 7 (0.33 ± 0.33), p < 0.05. Unlike TNF‐α, GI recovered to the baseline by day 14. Other periodontal parameters, PI, PD, BOP, and AL were not significantly altered by the gingival retraction procedure.

Conclusion: This pilot study supports the previous research that gingival retraction causes an acute injury that heals clinically in 2 weeks as is indicated by the GI. It also provides the first evidence that gingival retraction results in an elevation of the proinflammatory cytokine, TNF‐α, in GCF.
Communication Between the Dental Laboratory Technician and Dentist: Work Authorization for Fixed Partial Dentures
Authors: Afsharzand Zahra , Rashedi Behnoush , Petropoulos Vicki C.
Published: March 2006

Purpose: A questionnaire was sent to laboratory technicians to determine the level of communication between dentists and dental laboratories in specific areas of the work authorization forms for the fabrication of fixed partial dentures.

Materials and Methods: A select number of dental laboratories were randomly chosen from the National Association of Dental Laboratories (NADL) for each of the 50 states. The questionnaire was mailed to the laboratory directors for a total of 199 dental laboratories. The survey asked questions pertaining to the following areas of work authorization: legibility and thoroughness of prescriptions, patient information, choice of materials for the prosthesis, design of the prosthesis, and shade description. For each question, the number of responses received was tabulated and converted to a percentage.

Results: Of the 199 laboratories surveyed, 114 (57%) responded to the questionnaire. Results from this survey suggest that there is lack of communication between dentists and dental laboratories through work authorization forms regarding choice of metal alloy, type of porcelain to be used, and choice of margin and pontic design for the prosthesis.

Conclusions: Information obtained from the responding laboratories included effectiveness of work authorization forms. There were some similar trends indicated by the large percentage of dental laboratories agreeing on lack of communication by the dentists as reflected by the work authorization forms.
An Integrated Physical Dispersion and Behavioral Response Model for Risk Assessment of Radiological Dispersion Device (RDD) Events
Authors: Dombroski Matthew J. , Fischbeck Paul S.
Published: February 2006

A radiological dispersion device (RDD) or “dirty” bomb is a conventional explosive wrapped in radiological material. Terrorists may use an RDD to disperse radioactive material across a populated area, causing casualties and/or economic damage. Nearly all risk assessment models for RDDs make unrealistic assumptions about public behavior in their health assessments, including assumptions that the public would stand outside in a single location indefinitely. In this article, we describe an approach for assessing the risks of RDD events incorporating both physical dispersion and behavioral response variables. The general approach is tested using the City of Pittsburgh, Pennsylvania as a case study. Atmospheric models simulate an RDD attack and its likely fallout, while radiation exposure models assess fatal cancer risk. We model different geographical distributions of the population based on time of day. We evaluate aggregate health impacts for different public responses (i.e., sheltering‐in‐place, evacuating). We find that current RDD models in use can be improved with the integration of behavioral components. Using the results from the model, we show how risk varies across several behavioral and physical variables. We show that the best policy to recommend to the public depends on many different variables, such as the amount of trauma at ground zero, the capability of emergency responders to get trauma victims to local hospitals quickly and efficiently, how quickly evacuations can take place in the city, and the amount of shielding available for shelterers. Using a parametric analysis, we develop behaviorally realistic risk assessments, we identify variables that can affect an optimal risk reduction policy, and we find that decision making can be improved by evaluating the tradeoff between trauma and cancer fatalities for various RDD scenarios before they occur.
Adverse Selection and Capital Structure: Evidence from Venture Capital
Authors: Cumming Douglas
Published: March 2006

Venture capitalists (VCs) in all non–U.S. countries around the world have consistently reported the use of a variety of securities, including common equity, preferred equity, convertible preferred equity, debt, convertible debt, and combinations (in the U.S., VCs typically use convertible preferred equity, and there is a tax bias in favor of that instrument in the U.S.). The types of entrepreneurial firms that receive venture finance may be defined by a variety of characteristics, such as stage of development, type of industry, and capital requirements. Given this broad context observed in practice, previous research has not considered the extent to which different securities, among the complete class of forms of finance, attract different types of entrepreneurial firms. In this article, we investigate the empirical tractability of the adverse selection risks associated with capital structure from 4,114 first–round Canadian venture capital investments. We first characterize the nature of uncertainty (in terms of the risk of financing a lemon or a nut) facing investors for different types of entrepreneurial firms. We then show that VC syndication significantly mitigates problems of adverse selection.
Allocation of Attention to Portfolio Companies and the Performance of Venture Capital Firms
Authors: Jääskeläinen Mikko , Maula Markku , Seppä Tuukka
Published: March 2006

This article proposes that the attention allocated by venture capitalists to portfolio companies impacts their performance. The article develops arguments for optimal portfolio size and for the moderating roles of syndication frequency and role. The hypotheses receive support from analyses employing longitudinal data of the leading U.S. venture capital firms. Our results indicate the value of venture capitalist involvement and give guidance for its optimal allocation and syndication.
Entrepreneurial Team Development in Academic Spinouts: An Examination of Team Heterogeneity
Authors: Vanaelst Iris , Clarysse Bart , Wright Mike , Lockett Andy , Moray Nathalie , S'Jegers Rosette
Published: March 2006

This article examines the dynamics of entrepreneurial teams as they evolve through the different stages of a spin–out process. Using a unique, hand–collected set of data covering all team members in 10 cases, an in–depth analysis of the heterogeneity of team members’ experience and perception of the strategic orientation needed to attain different milestones in the spin–out process was performed. Our findings suggest that teams evolve over time and change in composition, and therefore, they cannot be studied as immutable entities. At the start of the venture formation, we introduced a new team role, the privileged witness, potentially specific for spinouts. Analysis of the teams indicates that the team's heterogeneity changes as it evolves through the different stages of the spin–out process. In particular, we found that new team members brought in different kinds of experience; however, they did not introduce a different view on doing business from the initial team members.
Protection of the Coronary Arteries During Epicardial Radiofrequency Ablation with Intracoronary Chilled Saline Irrigation: Assessment in an In Vitro Model
Authors: THYER ISAAC A. , KOVOOR PRAMESH , BARRY MICHAEL A. , POULIOPOULOS JIM , ROSS DAVID L. , THIAGALINGAM ARAVINDA
Published: February 2006

Introduction: The coronary arteries can be damaged during epicardial radiofrequency ablation (RFA) procedures. We hypothesized that intracoronary irrigation with chilled saline may be a useful technique for minimizing heat‐induced damage to the coronary artery endothelium during this procedure.

Methods and Results: Twenty‐nine ablation procedures were performed on 17 freshly excised ovine hearts. Radiofrequency current was delivered through an internally cooled, 4‐mm‐tip ablation catheter placed directly over the coronary artery (24 applications) and over noncoronary epicardium (5 applications). An Amplatz coronary catheter was used to internally irrigate the coronary artery with either 37°C or 5°C 0.9% saline (12 ablations each group). Fluroptic temperature probes were placed within the artery lumen under the ablation site and 15 mm distal from the ablation site. The peak intracoronary temperature directly under the ablation catheter was significantly lower (P = 0.001) in the chilled than in the nonchilled saline irrigation group (23.6°C, interquartile range [IQR] 15.7–39.8 vs 54.6°C, IQR 48.9–58.6). Blue tetrazolium stained lesion sections showed that the median distance between the ablation lesion and the artery wall was significantly higher (P = 0.004) for the chilled versus the nonchilled saline irrigation group (0.42 mm, IQR 0.25–0.70 vs 0.00 mm, IQR 0.00–0.28).

Conclusions: Intracoronary irrigation with chilled saline may protect the coronary artery endothelium from heat‐induced damage during epicardial RFA.
Initial Experience in the Use of Integrated Electroanatomic Mapping with Three‐Dimensional MR/CT Images to Guide Catheter Ablation of Atrial Fibrillation
Authors: DONG JUN , DICKFELD TIMM , DALAL DARSHAN , CHEEMA AAMIR , VASAMREDDY CHANDRASEKHAR R. , HENRIKSON CHARLES A. , MARINE JOSEPH E. , HALPERIN HENRY R. , BERGER RONALD D. , LIMA JOAO A.C. , BLUEMKE DAVID A. , CALKINS HUGH
Published: February 2006

Introduction: No prior studies have reported the use of integrated electroanatomic mapping with preacquired magnetic resonance/computed tomographic (MR/CT) images to guide catheter ablation of atrial fibrillation (AF) in a series of patients.

Methods and Results: Sixteen consecutive patients with drug‐refractory AF underwent catheter ablation under the guidance of a three‐dimensional (3D) electroanatomic mapping system (Carto, Biosense Webster, Inc., Diamond Bar, CA, USA). Gadolinium‐enhanced MR (n = 8) or contrast‐enhanced high‐resolution CT (n = 8) imaging was performed within 1 day prior to the ablation procedures. Using a novel software package (CartoMerge, Biosense Webster, Inc.), the left atrium (LA) with pulmonary veins (PVs) was segmented and extracted for image registration. The segmented 3D MR/CT LA reconstruction was accurately registered to the real‐time mapping space with a combination of landmark registration and surface registration. The registered 3D MR/CT LA reconstruction was successfully used to guide deployment of RF applications encircling the PVs. Upon completion of the circumferential lesions around the PVs, 32% of the PVs were electrically isolated. Guided by a circular mapping catheter, the remaining PVs were disconnected from the LA using a segmental approach. The distance between the surface of the registered 3D MR/CT LA reconstruction and multiple electroanatomic map points was 3.05 ± 0.41 mm. No complications were observed.

Conclusions: Three‐dimensional MR/CT images can be successfully extracted and registered to anatomically guided clinical AF ablations. The display of detailed and accurate anatomic information during the procedure enables tailored RF ablation to individual PV and LA anatomy.
Change in Size of Lesions Over 3 Weeks After Radiofrequency Ablation of Left Ventricle
Authors: KOVOOR PRAMESH , DALY MICHAEL , MIKHAIL MICHELLE , EIPPER VICKI , DEWSNAP BARBARA , ROSS DAVID L.
Published: February 2006

Introduction: The initial success or failure of radiofrequency ablation (RFA) does not always reflect the long‐term outcome that can lead to complications such as late atrioventricular block or recurrence of accessory pathways. We hypothesize that these occurrences may be due to a change in lesion size over time.

Methods and Results: Intramural RFAs were performed on five greyhounds at thoracotomy using an epicardial approach into the left ventricular (LV) wall. Twenty‐one gauge needle electrode ablations were created in the anterior aspect of the left ventricle. Radiofrequency energy was delivered at 600 Hz for 60 seconds and at an electrode temperature of 90°C. Eight ablations were created in each greyhound and the chest was closed. After 3 weeks, a further eight ablations were created under the same conditions in the lateral aspect of the LV, ensuring they were well away from the chronic lesions, and the dogs were sacrificed an hour later. All lesions were removed, stained with Gomori Trichrome and measured. There was no significant difference in lesion size detected in the 1‐hour‐old lesions compared with 3‐week‐old lesions. Acute lesions were well demarcated by an area of fibrous scar and a central necrotic region. Chronic lesions showed chronic inflammatory cells and strands of collagen.

Conclusions: This study shows no change in lesion dimension over time and hence a change in size may not contribute to a change in RFA outcome over time.
Transcranial Doppler Detection of Microembolic Signals During Pulmonary Vein Antrum Isolation: Implications for Titration of Radiofrequency Energy
Authors: KILICASLAN FETHI , VERMA ATUL , SAAD EDUARDO , ROSSILLO ANTONIO , DAVIS DONALEE A. , PRASAD SUBRAMANYA K. , WAZNI OUSSAMA , MARROUCHE NASSIR F. , RABER LARRY N. , CUMMINGS JENNIFER E. , BEHEIRY SALWA , HAO STEVEN , BURKHARDT J. DAVID , SALIBA WALID , SCHWEIKERT ROBERT A. , MARTIN DAVID O. , NATALE ANDREA
Published: March 2006

Background: Cerebrovascular events are an important complication during pulmonary vein antrum isolation (PVAI). Microembolic signals (MES) have been associated with stroke and neurological impairment. However, the incidence of MES during PVAI, and their relationship to microbubble formation and radiofrequency (RF) parameters are unknown.

Objectives: We sought to assess the relationship between MES, microbubble detection, and neurological outcome and the impact of RF titration strategy on these parameters.

Methods: We studied 202 patients in two groups undergoing PVAI using an intracardiac echocardiography (ICE)‐guided technique. MES were detected by transcranial Doppler (TCD) using insonation of the middle cerebral arteries. The number of microbubbles on ICE were qualitatively labeled as FEW, MODERATE, and SHOWER. In group I (n = 107), RF output was titrated to avoid microbubble formation and in group II (n = 95), standard power‐limited RF output was used.

Results: TCD detected MES in all 202 patients during PVAI with an average of 1,793 ± 547 per patient; 90% were detected during left atrial ablation. Over 85% of MES occurred after microbubbles. Group I patients had significantly lower numbers of MES (1,015 ± 438 per patient) compared to group II patients (2,250 ± 864 per patient) (P < 0.05). Group II also had a 3.1% incidence of acute neurological complications versus 0.9% in group I (P = 0.10). Patients with clinical events had significantly higher numbers of MES. There were no significant correlations between RF power, temperature, or impedence and MES number.

Conclusions: MES directly correlate to the amount of microbubble formation on ICE, and may result in cerebroembolic complications. Titration of RF according to microbubble formation by ICE during PVAI may be important for minimizing the occurrence of MES and possibly acute neurological complications.
A Method for Estimating Cell Volume of Amoebae Based on Measurements of Cell Length of Motile Forms: Physiological and Ecological Applications
Authors: ROGER ANDERSON O.
Published: March 2006

ABSTRACT. A novel method of estimating the cell volume of non‐testate, free‐living amoebae is presented. Measurements of the length (L) of motile forms of some amoebae, obtained by applying some basic rules, can be used to calculate diameter (D) using a relatively simple formula, derived from regression analysis (N=39): D=0.6L. Important physiological and ecological variables, including carbon content and respiratory rate, can then be easily calculated using this estimated cell volume.
Carcinosarcoma of the prostate
Authors: LINDBOE C. F. , KLEM K. H.
Published: March 2006

We report the case of a 66‐year‐old man who was diagnosed as having prostatic adenocarcinoma with widespread skeletal metastases. After treatment with a luteinizing hormone‐releasing hormone analog for one year, a second biopsy revealed transformation of the tumour into a carcinosarcoma with heterogeneous and unusual findings in the carcinomatous as well as the sarcomatous component. Among others, these included a papillary growth pattern and a liposarcomatous differentiation. The patient died 5 months after the diagnosis of carcinosarcoma.
The influence of adhesive and invasive properties of Staphylococcus aureus defective in fibronectin‐binding proteins on secretion of interleukin‐6 by human endothelial cells
Authors: SÖDERQUIST BO , ALRIKSSON INGEGERD , KÄLLMAN JAN , KIHLSTRÖM ERIK
Published: March 2006

Fibronectin‐binding proteins (FnBP) are surface adhesins of Staphylococcus aureus documented to be virulence attributes in, for example, endovascular infections. By using mutants of S. aureus defective in the FnBPA and B genes we have investigated whether these adhesins affect cytokine expression in human umbilical vein endothelial cells (HUVEC). S. aureus expressing FnBPA and B adhered to and were internalized into HUVEC to a greater extent compared to mutants defective in expression of FnBP. Production and release of IL‐6 was higher from endothelial cells infected with the parent FnBP‐expressing strain compared to the FnBP‐defective mutants. These results indicate that adhesion to and invasion of S. aureus into endothelial cells are important regulators of cytokine expression.
Diversity of γδ T cells in patients with Behcet's disease is indicative of polyclonal activation
Authors: Freysdottir J , Hussain L , Farmer I , Lau S‐H , Fortune F
Published: February 2006

Objective:  Behcet's disease (BD) is a multisystemic disease, with vasculitic lesions in the oral and genital mucosa, eyes, joints, skin and brain. We have previously found that γδ T cells are increased in peripheral blood of BD patients. The aim of this study was to investigate the extent of γδ T cells in oral biopsies from BD patients with special emphasis on the restriction of Vγ and Vδ usage.

Patients and methods:  Expression of Vγ and Vδ chains on peripheral blood γδ T cells from 31 BD patients and 19 healthy controls was analysed by flow cytometry and the expression of Vγ and Vδ chains in nine ulcerated and eight non‐ulcerated oral mucosa from BD patients and non‐ulcerated oral mucosa from three healthy controls was analysed by immunohistochemistry.

Results:  Vγ9 and Vδ2 were the predominant chains expressed in peripheral blood of BD patients, although other Vγ and Vδ chains were also expressed. The presence of γδ T cells was only observed in the ulcerated oral mucosa but not in the non‐ulcerated mucosa from the BD patients, and not in the non‐ulcerated mucosa from the healthy controls. These γδ T cells showed no preferential expression of any of the Vγ or Vδ chains.

Conclusion:  These data suggest a polyclonal rather than oligoclonal activation of the γδ T cells. This may indicate that during repeated inflammation of the oral mucosa, the γδ T cells are responding to a wide variety of antigenic stimuli with consequent expansion of γδ T cells expressing various Vγ and Vδ chains and that different antigenic stimuli or responses may be responsible for the clinical heterogeneity of the disease.
Expression of basement membrane components in odontogenic cysts
Authors: Poomsawat S , Punyasingh J , Weerapradist W
Published: February 2006

Objective:  To compare the expression of basement membrane components (BMCs), including laminins 1 and 5, collagen type IV, and fibronectin in odontogenic keratocysts (OKCs) with dentigerous cysts (DCs) and radicular cysts (RCs).

Materials and methods:  Basement membrane components were analysed in 20 OKCs, 20 DCs and 20 RCs using an immunohistochemical technique.

Results:  Odontogenic keratocysts, DCs and RCs showed positive reaction to all BMCs studied, with different distributions and intensity. OKCs showed continuous linear deposits for laminins 1 and 5 but two staining patterns (continuous and discontinuous) for collagen type IV and fibronectin. DCs exhibited continuous linear deposits for laminins 1 and 5 and collagen type IV but a discontinuous linear deposit for fibronectin. RCs displayed similar results to DCs for laminin 1, collagen type IV and fibronectin. Laminin 5 in RCs had two staining patterns. Constant results in all cysts were strong intensity for laminin 1 and moderate intensity for laminin 5.

Conclusions:  Substantial differences in the expression of BMCs among studied cysts were not observed, suggesting that the separation of the epithelial lining in OKCs is not associated with the existence of these proteins.
Causative agents of onychomycosis — a retrospective study
Authors: Mügge Claudia , Haustein Uwe‐Frithjof , Nenoff Pietro
Published: March 2006

Background: Dermatophytes, yeasts and moulds all are potential causative agents of onychomycosis.The aim of this study was to determine the percentage of cases of onychomycoses caused by each group. In addition, the responsible genus and species was identified for each nail infection.

Patients and Methods: In a retrospective study performed at the Department of Dermatology of the Leipzig University, 5 077 nail samples from 4 177 patients – 2 240 women and 1 937 men – with a variety of nail changes – not just onychomycosis – were investigated. 75% were toenails, 23% fingernails, and 2% from both sites.

Results: Both microscopic and/or cultural detection of fungi (dermatophytes, yeasts and moulds) were successful in 54% of samples.Causative fungal agents were: 68% dermatophytes, 29% yeast, and 3% moulds. The most frequently detected dermatophyte species were T. rubrum (91%), and T. mentagrophytes (7.7%).Among yeasts, C. parapsilosis (42%) was most common,followed by C. guilliermondii (20.1%), C. albicans (14.2%), and Trichosporon spp. (10%).Scopulariopsis brevicaularis (43%) was the most frequent mould. The percentage of mixed fungal infections was 22%.

Conclusions: Dermatophytes, in particular T.rubrum, but also T. mentagrophytes, are the most frequently isolated causative agents in onychomycosis. In addition, yeasts may be isolated relatively frequently, while moulds are uncommon.