bluuebunny/crossref_metadata_2025 huggingface dataset:
The spatial distribution pattern of the brown planthopper Nilaparvata lugens Stål (Homoptera: Delphacidae) in west Java, Indonesia
Authors: Kusmayadi Ayi , Kuno Eizi , Sawada Hiroichi
Published: October 2006

Spatial distribution pattern of the brown planthopper (BPH) was analyzed at 9 experimental fields in the northern part of West Java during two consecutive rice cropping seasons, i.e., wet and dry seasons.

The population of each developmental stage and wing form of BPH at each location showed consistent departure from the random (Poisson) distribution, the variances of the densities in most cases exceeding their means. Namely, the distribution pattern of BPH per hill of rice plant was found to have a general tendency to be aggregated or contagious and to fit fairly well to the negative binomial model. The tendency for aggregation was further confirmed by both the β‐values of ‐m regression being larger than unity and the CA‐values being larger than zero for each developmental stage.

Although significant variations in the distribution pattern as measured by β‐ or CA‐value were observed between different developmental stages, between wing forms and among locations, the degree of aggregation for a given developmental stage at each experimental field remained fairly stable throughout the crop period, despite wide temporal changes in population density.

Possible factors to explain these characteristics of the spatial distribution pattern of the BPH in West Java were discussed with reference to the process generating it.
Demography of an island population of the lizard, Eumeces okadae, on Miyake‐jima, Izu Islands
Authors: Hasegawa Masami
Published: October 2006

The demography of the lizard Eumeces okadae was studied for 4 years on Miyake‐jima, in the Izu Islands, central Japan. Most males matured at 3 years of age with a mean snout‐vent length of 77.5 mm. Females matured at 3–4 years with a mean SVL of 77.8 mm, and reproduced biennially thereafter. Growth continued after maturity with a decreasing rate. In females, annual growth was negligible in reproductive years, but resumed markedly in non‐reproductive years. Clutch size increased with SVL and was used to construct a fecundity schedule. Population density (exclusive of hatchlings) was estimated to be ca. 4000 individuals/ha in August, an exceptionally high density for lizards. Before introduction of the weasel onto Miyake‐jima, low predation pressure had allowed E. okadae to maintain a high population density. Estimated annual survival rates were 36% for hatchlings, 56% for yearlings, 80% for 2‐year‐olds, 63% for adult males and 76% for adult females. The cohort generation time (6.95 years) was so long that the E. okadae population can be characterized by a combination of low natality and slow turnover.
Factors influencing development and survival of Culex pipiens pallens larvae (Diptera: Culicidae) in polluted urban creeks
Authors: Mogi M. , Okazawa T.
Published: October 2006

Factors influencing development and survival of Culex pipiens pallens immatures in polluted urban creeks were studied in Saga, Japan. Addition of food shortened developmental durations and increased pupal size in floating cages at only the least polluted site out of 4 study sites. There was no evidence for developmental delay due to overcrowding in natural populations. Survival was not increased by artificial feeding at any site. Using the developmental parameters obtained for caged cohorts, survival in natural populations was estimated from differences between the actual number and the expectation if there were no mortality. Pupation rates ranged from 1> to >10% by site and season. Mortality due to predation, evaluated from the difference in pupation rates between caged and natural populations, exceeded 30% in 4 out of 6 cases (twice at 2 sites and once at the other 2 sites). Lethal factors in the creek water caused the predominant mortality in 2 other cases. Regulation of C. pipiens pallens population breeding in eutrophic, open creeks was discussed in the context of larval dispersal through behavioral interference.
The spatial patterns of parasitism of eumenid wasps, Anterhynchium flavomarginatum and Orancistrocerus drewseni by the miltogrammine fly Amobia distorta
Authors: Itino Takao
Published: October 2006

Spatial patterns of parasitism of eumenid wasps Anterhynchium flavomarginatum and Orancistrocerus drewseni by the miltogrammine fly Amobia distorta were studied in Kyoto, Japan during 1980–1984.

In generations of low (<5%) and medium (5–20%) parasitism, percent parasitism per shed (the habitat of the hosts) increased as a function of host density. Conversely, in generations of high (>20%) parasitism, percent parasitism was rather constant over different host densities.

The spatial distributions of adult miltogrammine flies among sheds were censused in generations of low and medium parasitism. The frequency of observations of adult miltogrammine flies was higher at sheds of higher host density (aggregative behavioral response), but on the other hand, the adult miltogrammine flies distributed in an underdispersed (or regular) manner in relation to other conspecifics.

The spatially density independent relationship between host density and percent parasitism in generations of high parasitism was explained in relation to parasitoid dispersal from patches of high parasitoid density.
The dynamics of outbreaks: Further simulation experiments with the western tent caterpillar
Authors: Thompson W. A. , Vertinsky I. B. , Wellington W. G.
Published: October 2006

A stochastic model of western tent‐caterpillar populations on southern Vancouver Island was used to assess conditions leading to outbreaks. Three qualitatively different populations‐declining, minimal, and recovering‐were exposed to six‐year climatic sequences incorporating various combinations of good, bad, and mediocre spring weather. Starting populations were either distributed randomly or concentrated in and around small‐, medium‐, or large refuges.

The results showed that virtually any type of population could temporarily increase in numbers during two highly favorable springs. Only a very few vigorous populations, however, could sustain the momentum required to surge to outbreak proportions. No low‐quality population could do so. And even vigorous populations could not achieve outbreak status unless they were initially concentrated in a sufficiently large refuge that was close enough to potentially suitable habitats to permit rapid immigration into such places as soon as their local climates improved.

The concept of “climatic release” of insect populations is discussed in the light of these findings. The results demonstrate that climatic release is inextricably linked with a population's qualitative profile and spatial distribution.
Accuracy and precision of the topological mapping procedure for estimating within‐tree populations of bark beetles
Authors: Pulley Paul E. , Coulson Robert N. , Kelly Claude L.
Published: October 2006

The accuracy and precision of the topological mapping procedure for estimating within‐tree populations of bark beetles was investigated for a variety of different sampling conditions. Simulation techniques were used to define the mean and standard deviation of proportional errors encountered in estimation under different sampling intensities. The number of samples collected at a particular height and the vertical spacing between heights were varied. Information presented should aid in developing sampling plans for studies of bark beetle populations and will permit the reexamination and/or recovery of historical data sets on bark beetle populations.
Number of generations necessary to attain eradication of an insect pest with sterile insect release method: A model study
Authors: Itô Yosiaki , Kawamoto Hitoshi
Published: October 2006

Simulation of the sterile insect release process was carried out based on a system which consisted of a logistic population model and Poisson‐binomial model for normal, sterile and combined matings. From the results, relationship between the intrinsic rate of natural increase and the sterile vs. normal ratio necessary to attain eradication of the target pest species were presented. The effects of weakened sperm competitiveness and the increased number of matings per female were not so strong. On the other hand, a given rate of immigration could be a cause of failure of the eradication. A simple method to calculate relationship between hatchability and sterile vs. normal ratio was presented.
Comparative population studies of three Pieris butterflies, P. rapae, P. melete and P. napi, living in the same area
Authors: Ohsaki Naota
Published: October 2006

The adult populations of three Pieris butterflies, P. rapae, P. melete and P. napi, were studied in an area of their coexistence throughout the flight seasons by using the mark‐and‐recapture method. The study area, about 3×1.5 km, was set up in a farm village surrounded by the mountainous area in Inabu, Aichi Prefecture.

The habitats were qualified by the four factors, i. e., oviposition plants, adult nector plants, roosting‐sites and light conditions. Between P. rapae and P. napi, there were sharp differences with regards to overall habitat preferences. P. melete had the widest preferences for all the habitat resources, which overlapped greately with requirements of P. rapae and P. napi. P. melete and P. rapae showed similar preferences for oviposition plants, but the former preferred shaded habitats while the latter preferred sunny places. P. melete and P. napi, having similar preferences for shaded situations, showed differences in the preferences for oviposition plants. Moreover, three species of Pieris were different in their preferences for adult nector plants. Thus, they were more likely to partition habitat resources rather than competing for them.

The habitat structures of each species in respect of time, space and stability to weather changes were much different each other in the same area. The habitat of P. rapae was temporary, localized and unstable. While, that of P. melete was more permanent, widespread and stable than that of P. rapae. P. napi seemed to live in the intermediate habitat, i. e., permanent, localized and stable one.
Dispersal and reproductive properties of sugarcane bugs, Cavelerius saccharivorus
Authors: Murai Minoru
Published: October 2006

The distribution of sugarcane bugs, Cavelerius saccharivorus is remarkably patchy at time of the peak emergence of the first generation adult in early summer. In population near carrying capacity 70% of adults become macropterous, and they move to sparse populations or vacuum areas.

The experiment on the reproductive difference between females from field populations with different densities, showed that the overcrowding restricted their oviposition. On the further experiment it was shown that reproductive ability of macropterous adults or dispersers was not much inferior to that of brachypterous from sparse populations. Overcrowding at time of the peak emergence is reduced by the dispersal. Hence the intraspecific competition is a transient condition. The oviposition is at first restricted in residents of dense populations as compared with brachypterous adults of sparse populations, but the difference becomes small as the former density decreases by the emigration.

The last section considers the relation of the reproductive rate and dispersal risk to the rate of dispersal with the simple model, which explains the characteristic dispersal of this species.
Intrastriatal hypoxanthine administration affects Na+,K+‐ATPase, acetylcholinesterase and catalase activities in striatum, hippocampus and cerebral cortex of rats
Authors: Bavaresco Caren Serra , Chiarani Fabria , Wajner Moacir , Netto Carlos Alexandre , de Souza Wyse Angela Terezinha
Published: October 2006

The aim of this study was to investigate the effects of a single intrastriatal injection of hypoxanthine, the major metabolite accumulating in Lesch–Nyhan disease, on Na+,K+‐ATPase, acetylcholinesterase and catalase activities in striatum, cerebral cortex and hippocampus of rats at different post‐infusion periods. Adult Wistar rats were divided in two groups: (1) vehicle‐injected group (control) and (2) hypoxanthine‐injected group. For Na+,K+‐ATPase activity determination, the animals were sacrificed 3 h, 24 h and 7 days after drug infusion. For the evaluation of acetylcholinesterase and catalase activities, the animals were sacrificed 30 min, 3 h, 24 h and 7 days after hypoxanthine infusion. Results show regional and time dependent effects of hypoxanthine on Na+,K+‐ATPase, acetylcholinesterase and catalase activities. The in vitro effect of hypoxanthine on the same enzymes in striatum was also investigated. Results showed that hypoxanthine inhibited Na+,K+‐ATPase, but not the activities of acetylcholinesterase and catalase in rat striatum. We suggest that these modification on cerebral biochemical parameters (Na+,K+‐ATPase, acetylcholinesterase and catalase activities) induced by intrastriatal administration of hypoxanthine in all cerebral structures studied, striatum, hippocampus and cerebral cortex, could be involved in the pathophysiology of Lesch–Nyhan disease.
Inception of the Northern European ice sheet due to contrasting ocean and insolation forcing
Authors: Risebrobakken Bjørg , Dokken Trond , Otterå Odd Helge , Jansen Eystein , Gao Yongqi , Drange Helge
Published: October 2006

About 115,000 yr ago the last interglacial reached its terminus and nucleation of new ice-sheet growth was initiated. Evidence from the northernmost Nordic Seas indicate that the inception of the last glacial was related to an intensification of the Atlantic Meridional Overturning Circulation (AMOC) in its northern limb. The enhanced AMOC, combined with minimum Northern hemisphere insolation, introduced a strong sea–land thermal gradient that, together with a strong wintertime latitudinal insolation gradient, increased the storminess and moisture transport to the high Northern European latitudes at a time when the Northern hemisphere summer insolation approached its minimum.
A correlative study of NF-κB activity and cytokines expression in human chronic nasal sinusitis
Authors: Xu R , Xu G , Shi J , Wen W
Published: October 2006

A growing body of literature suggests that cytokines play an important part in the pathogenesis of chronic nasal sinusitis. However, the mechanism by which the expression of cytokines in chronic nasal sinusitis is upregulated has not been well documented. The present study investigated the role of nuclear factor-kappa B (NF-κB) activation in upregulating the expression of interleukin-5, -6 and -8 (IL-5, IL-6 and IL-8). We titrated the levels of IL-5, IL-6 and IL-8 in nasal mucosa in 52 cases of chronic nasal sinusitis and 12 normal subjects using enzyme-linked immunosorbent assay. According to whether allergic rhinitis was associated or not, we subdivided the patients into the AR group (with allergic rhinitis) and the NAR group (without allergic rhinitis). Semi-quantitative reverse transcription-polymerase chain reaction and immunohistochemical staining were used to evaluate expression and activation of NF-κB P50 and P65 subunits in nasal mucosa. The correlation between activities of P50 and P65 and cytokines expression was analysed. Our results showed that IL-5, IL-6 and IL-8 in both the AR and NAR groups were strikingly elevated in comparison with the control group (all p < 0.01 for AR group; p < 0.05, 0.05, 0.01, respectively, for NAR group); and they were even higher in the AR group than those in the NAR group (p < 0.01, 0.05, 0.01, respectively). P50 and P65 mRNA levels in both AR and NAR groups were markedly greater than those in the control group (all p < 0.01); and the AR group had further higher levels as compared with the NAR group (both p < 0.05). Immunohistochemical study revealed that nucleus-positive rates of P50 and P65 in both AR and NAR groups were significantly higher than those of the control group (all p < 0.01), and they were much greater in the AR group in comparison with the NAR group (all p < 0.01). Pearson correlation analysis demonstrated that P50 and P65 nucleus-positive rates were closely correlated with IL-6 and IL-8 levels, but not IL-5, with a correlation coefficient of 0.49 for P50 and IL-6, 0.54 for P50 and IL-8, 0.61 for P65 and IL-6, and 0.66 for P65 and IL-8 (all p < 0.01). In conclusion, upregulated expression and activation of NF-κB P50 and P65 might be one of the mechanisms for induction of IL-6 and IL-8 expression in chronic nasal sinusitis. Association of allergic rhinitis with chronic nasal sinusitis further enhanced NF-κB activity, and subsequently lead to even stronger expression of IL-6 and IL-8. IL-5 expression appeared to be independent of NF-κB pathway in chronic nasal sinusitis.
Management of surgical airway emergencies by junior ENT staff: a telephone survey
Authors: Awad Z , Pothier D D
Published: October 2006

Objective: To determine levels of confidence in the management of surgical airway emergencies by junior ENT staff.

Design: Telephone survey.

Participants: 100 Senior House Officers (SHOs) from 100 hospitals in the UK, providing 24 hour first on-call emergency ENT cover.

Method: A list of questions was put to participants. The effects of different variables on confidence with airway emergencies and what SHOs considered to be adequate training were compared.

Results: Most SHOs provided cover for the management of surgical airway emergencies. Many of the participants were not confident to handle airway emergencies or felt that their training was inadequate. As expected, the amount of previous experience in ENT and the ability to perform advanced airway procedures gave SHOs greater confidence, but attendance at airway courses did not.

Conclusion: Confidence in the management of airway problems is variable and does not correlate well with perceived adequacy of training. We suggest that systems of training in airway management are improved. Training issues may be better approached at an individual level, where deficiencies can be addressed.
The effect of inulin on new and on patent infections ofTrichuris suisin growing pigs
Authors: PETKEVIČIUS S. , THOMSEN L. E. , BACH KNUDSEN K. E. , MURRELL K. D. , ROEPSTORFF A. , BOES J.
Published: October 2006

The objective of this experiment was to investigate the potential influence of inulin on the establishment of new and patent infections ofTrichuris suisin growing pigs. Two experimental diets were formulated based on barley flour with either added insoluble fibre from oat husk (Diet 1) or a pure inulin (16%) supplementation (Diet 2). Twenty-eight 10-week-old pigs were divided randomly into 4 groups (Groups 1–4) each of 7 pigs. After 3 weeks adaptation to the experimental diets all pigs were infected with a single dose of 2000 infectiveT. suiseggs. Group 1 was fed Diet 1 until 7 weeks post-infection (p.i.) and Group 3 until 9 weeks p.i., Group 2 was fed Diet 2 until 7 weeks p.i., Group 4 was fed Diet 1 until week 7 p.i. and was switched-over from Diet 1 to Diet 2 until week 9 p.i. Seven weeks p.i. pigs in Groups 1 and 2 were slaughtered, and pigs in Groups 3 and 4 were slaughtered at 9 weeks p.i.Trichuris suisworm burdens were determined for all pigs. Inulin-fed pigs (Group 2) exhibited an 87% reduction in EPG, compared to the pigs on standard diet (Group 1) (P<0·0001). The number of worms recovered at week 7 p.i. from pigs on the inulin diet (Group 2) was significantly reduced by 71%, compared to the pigs on standard diet (Group 1) (P<0·01). At week 9, worm recovery in pigs on the inulin diet switch protocol (Group 4) was reduced by 47% compared to the control pigs in Group 3 (P<0·01). Further, the inulin-fed pigs exhibited a significant reduction in female worm fecundity and worm large intestine location was more distal compared to those from pigs on standard diet. These results demonstrate that inclusion of the highly degradable fructose polymer inulin in the diet leads to significant reductions inT. suisestablishment, egg excretion, and female worm fecundity and can be used as a treatment for patent infections.
Antiparasitic effect of calcium and magnesium ion-free buffer treatments against a common monogeneanNeobenedenia girellae
Authors: OHASHI H. , UMEDA N. , HIRAZAWA N. , OZAKI Y. , MIURA C. , MIURA T.
Published: October 2006

This study investigated a new effective method for controlling the capsalid monogeneanNeobenedenia girellae. We examinedin vitroandin vivothe effect on the percentage survival ofN. girellaein buffers containing different metallic ions. Decreased survival was observed in buffer solutions lacking two ions. In particular, the percentage survival ofN. girellaewas significantly decreased after 10 min exposure to buffer containing neither Ca2+nor Mg2+. Transmission electron microscopic observations showed that treatment with this buffer disrupted intercellular junctions. This significant effect on percentage survival ofN. girellaeusing Ca2+/Mg2+-free buffer was confirmed in anin vivoassay. Ca2+/Mg2+-free buffer had no effect on the condition of the host, spotted halibutVerasper variegates(Pleuronectidae). These results suggest that treatment with Ca2+/Mg2+-free buffer is a new effective control method, which could replace existing control methods.
Proteomic analysis ofEntamoeba histolytica
Authors: TOLSTRUP J. , KRAUSE E. , TANNICH E. , BRUCHHAUS I.
Published: October 2006

In this study, the proteome of axenically grownEntamoeba histolyticaparasites was explored by two-dimensional gel electrophoresis (2-DE), employing a practical and effective procedure for the solubilization ofE. histolyticaproteins. Approximately 900 protein species in the pH range between 4 and 7 were detected by Coomassie Blue staining. Ninety-five spots were excised, trypsinated and subjected to mass spectrometry. The resultant data from peptide mass fingerprints were compared with those available in theE. histolyticagenome and the (non-redundant) National Center for Biotechnology Information (NCBI) databases for the identification and categorization of proteins. Sixty-three of the proteins identified were predicted to relate to the cytoskeleton, surface, glycolysis, RNA/DNA metabolism, the ubiquitin-proteasome system, vesicular trafficking and signal transduction. The present study demonstrates, for the first time, that corresponding genes are indeed expressed inE. histolyticaand provides a foundation for further proteomic studies of this parasite.
Starting as we mean to go on. Why we need a theoretically informed historical archaeology in Ireland
Authors: O'Keeffe Tadhg
Published: October 2006

Dr Horning's paper touches issues of fundamental importance both to contemporary Ireland as a place of historically rooted cultural contestation and to the discipline of historical archaeology in Ireland. It has a core message: archaeologists can blunt some of those sharp edges of cultural-political division that originated in Plantation-era settlement by revealing how historical sites that seem on the surface to belong on one or other aggrieved side in the island's history are susceptible to more nuanced, and arguably more legitimate, interpretations.
Use of Army Weapons and Private Firearms for Suicide and Homicide in the Region of Basel, Switzerland
Authors: Frei A. , Han A. , Weiss M.G. , Dittmann V. , Ajdacic-Gross V.
Published: October 2006

Objectives: Switzerland has one of the highest rates of firearm suicides in the world. International studies show a positive correlation between the rate of households with guns and femicides with guns. Because its defense system requires a militia to keep personal firearms at home, Switzerland has a high rate of households with a gun. Methods: Records of suicides in the region of Basel between 1992 and 1996 were reviewed. Suicides with either army weapons or private firearms and suicides by other means were compared. Methods and types of homicides that occurred in the region at the same time were also analyzed. Findings: Firearm suicides were clearly the most frequent means of suicide. They were also used in 30.0% of domestic homicides, although other means were used at similar rates. Firearms for suicide were mainly used by men, especially army weapons. These men were younger, professionally better qualified, and fewer had ever been treated in one of the local state psychiatric services. Discussion: The use of firearms for suicide, rather than homicide, and particularly of army weapons by young, well-educated men, requires more attention in debates and informed policy regarding access to firearms and suicide prevention in Switzerland.
Cross‐borehole ground‐penetrating radar for monitoring and imaging solute transport within the vadose zone
Authors: Chang Ping‐Yu , Alumbaugh David , Brainard Jim , Hall Laila
Published: October 2006

A two‐stage salt infiltration experiment was conducted to simulate vadose zone contaminant transport and to investigate mechanisms that affect the development of contaminant plumes in the unsaturated zone. A low‐concentration sodium chloride solution (1024 ppm) was first infiltrated for 7 months through one third of a specially designed infiltrometer at a rate of 2.7 cm/d, with tap water infiltrating through the remaining two thirds at the same rate. This first stage was followed by 3 months of running tap water through the entire infiltrometer to flush the system while maintaining the same unsaturated infiltration conditions. Next, the concentration of the sodium chloride solution was increased to 6900 ppm, which was introduced at the same infiltration rate over a different one third of the infiltrometer for 3 months. This paper focuses on using cross‐borehole ground‐penetrating radar attenuation tomography to image the developing plume in a time‐lapse sense. Attenuation is shown to increase with increasing salt concentration, and the time‐lapse images indicate that regions of anomalous attenuation develop in locations where pockets of higher moisture content exist. This suggests that either preferential transport pathways develop within the finer‐grained sediments exhibiting greater water retention capability or salt ions are being incorporated into the mineral surficial charge within the fine‐grained materials.
Effect of temporally correlated recharge on fluctuations of groundwater levels
Authors: Zhang You‐Kuan , Li Zhongwei
Published: October 2006

The effect of temporally correlated groundwater recharge, R(t), on fluctuations of the hydraulic head, h(t), was investigated with theoretical analyses and numerical simulations. Under an exponentially correlated recharge (ECR) process, analytical solutions for the hydraulic head covariance, Chh, and variance, σh2, were derived with a linear reservoir model. It was found that Chh and σh2 are time‐dependent or nonstationary and reduce to those derived in a previous study for a white noise recharge (WNR) when the correlation timescale of the recharge process approaches zero. It is also found that σh2 for ECR is proportional to t2, while that for WNR is proportional to t for a substantial period of time, indicating that h(t) under ECR may vary as a smooth curve with no fractal characteristics (D = 1.0), while h(t) under WNR fluctuates as a Brownian motion (D = 1.5). The theoretical findings were verified by numerical simulations: The power spectra of the simulated heads with a one‐dimensional transient groundwater flow model under ECR were shown to have distinct slopes in the log‐log plot with D = 1.02. It was emphasized that the effect of temporal correlation in groundwater recharge is to dampen the fluctuations of the head and base flow and that daily groundwater recharge rates may have little temporal correlation in the hydrogeological conditions similar to the Walnut Creek site.
Ocean margin densities and paleoestimates of the Atlantic meridional overturning circulation: A model study
Authors: Hirschi J. J.‐M. , Lynch‐Stieglitz J.
Published: October 2006

An eddy‐permitting numerical ocean model is used to test to what extent the Atlantic meridional overturning circulation (MOC) can be reconstructed from sea water densities at the ocean margins. By gradually reducing the number of locations where the densities are known and by adding systematic and random errors comparable to those expected in paleoreconstructions of sea water densities, we test if a reliable picture of the MOC can still be obtained. Our results show that even with only 0.07% of the boundary densities the mean state of the MOC as well as its variability can be reconstructed. The addition of a systematic error results in an overestimation or underestimation of the meridional transport. With a random error similar to the one expected for paleoestimates of the density the mean state of the MOC can still be reproduced, especially north of 40°N. However, the random noise largely masks the relatively modest MOC variability observed in the model run. For both systematic and random noise in the density field there is a larger sensitivity for MOC reconstructions the closer a location is from the equator. For a measuring campaign that aims to infer past states of the Atlantic MOC on the basis of boundary densities, the present study suggests that the best strategy is to collect data that allow estimation of the basin‐wide vertical density structure between 40°N and 50°N. Information from only a few latitudes is sufficient for a reasonable representation of the mean MOC state.
Configuration and dynamics of the Jovian magnetosphere
Authors: Fukazawa Keiichiro , Ogino Tatsuki , Walker Raymond J.
Published: October 2006

A massive rotating equatorial plasma sheet dominates Jupiter's magnetosphere and the solar wind and the interplanetary magnetic field (IMF) are not thought to be as important as at Earth. However, in a recent simulation study we found that for a purely northward IMF the Jovian magnetosphere reached an unstable state in which a nearly periodic series of magnetic X and O lines were launched tailward. In this study we have carried out three‐dimensional global magnetohydrodynamic simulations to investigate the causes of this dynamic behavior. First, we examined the effects of dynamic pressure on the magnetospheric configuration in the absence of an IMF. We examined a series of northward IMF simulations in which we varied both the IMF magnitude and dynamic pressure. If the outer edge of the rotating plasma sheet is far from the X‐line (for large pressure and small IMF), the reconnected flow reaches the dawn magnetopause and exits down the tail. If the neutral line forms closer to the rotation boundary (small pressure and IMF), then the reconnected flux tubes can convect all of the way around Jupiter. When they reach the nightside, they become stretched tailward and can reconnect again. This leads to the periodic behavior. If the neutral line forms very close to the rotation boundary (large pressure and IMF), the Jupiterward flow compresses the rotating plasma sheet. In this case the flow goes around Jupiter but the flux tubes return along the dusk magnetopause and do not participate in reconnection a second time.
Imaging of Brain Hypoxia in Permanent and Temporary Middle Cerebral Artery Occlusion in the Rat using 18F-Fluoromisonidazole and Positron Emission Tomography: A Pilot Study
Authors: Takasawa Masashi , Beech John S , Fryer Tim D , Hong Young T , Hughes Jessica L , Igase Keiji , Jones P Simon , Smith Rob , Aigbirhio Franklin I , Menon David K , Clark John C , Baron Jean-Claude
Published: October 2006

In acute stroke, the target of therapy is the severely hypoxic but salvageable tissue. Previous human studies using 18F-fluoromisonidazole and positron emission tomography (18F-FMISO PET) have shown high tracer retention indicative of tissue hypoxia, which had normalized at repeat scan >48 h later. In the only validation study of 18F-FMISO, using ex vivo autoradiography in thread middle cerebral artery occluded (MCAo) rats, there was unexpected high uptake as late as 22 h after reperfusion, raising questions about the use of 18F-FMISO as a hypoxia tracer. Here we report a pilot study of 18F-FMISO PET in experimental stroke. Spontaneous hypertensive rats were subjected to distal clip MCAo. Three-hour dynamic PET was performed in 7 rats: 3 normals, 1 with permanent MCAo (two sessions: 30 mins and 48 h after clip), and 3 with temporary MCAo (45 mins, n = 1; 120 mins, n = 2; scanning started 30 mins after clip removal). Experiments were terminated by perfusion—fixation for standard histopathology. Late tracer retention was assessed by both compartmental modelling and simple side-to-side ratios. In the initial PET session of the permanent MCAo rat, striking trapping of 18F-FMISO was observed in the affected cortex, which had normalized 48 h later; histopathology revealed pannecrosis. In contrast, there was no demonstrable tracer retention in either temporary MCAo models, and histopathology showed ischemic changes only. These results document elevated 18F-FMISO uptake in the stroke area only in the early phase of MCAo, but not after early reperfusion nor when tissue necrosis has developed. These findings strongly support the validity of 18F-FMISO as a marker of viable hypoxic tissue/penumbra after stroke.
Dynamics of Changes in Blood Flow, Volume, and Oxygenation: Implications for Dynamic Functional Magnetic Resonance Imaging Calibration
Authors: Kida Ikuhiro , Rothman Douglas L , Hyder Fahmeed
Published: October 2006

Changes in cerebral blood flow (CBF), volume (CBV), and oxygenation (blood-oxygenation level dependent (BOLD)) during functional activation are important for calculating changes in cerebral metabolic rate of oxygen consumption (CMRo2) from calibrated functional MRI (fMRI). An important part of this process is the CBF/CBV relationship, which is signified by a power-law parameter: γ = ln (1 + Δ CBV/ CBV)ln (1 + Δ CBF/ CBF). Because of difficulty in measuring CBF and CBV with MRI, the value of γ is therefore assumed to be ~0.4 from a prior primate study under hypercapnia. For dynamic fMRI calibration, it is important to know if the value of γ varies after stimulation onset. We measured transient relationships between ΔCBF, ΔCBV, and ΔBOLD by multimodal MRI with temporal resolution of 500 ms (at 7.0 T) from the rat somatosensory cortex during forepaw stimulation, where the stimulus duration ranged from 4 to 32 secs. Changes in CBF and BOLD were measured before the administration of the contrast agent for CBV measurements in the same subjects. We observed that the relationship between ΔCBF and ΔCBV varied dynamically from stimulation onset for all stimulus durations. Typically after stimulation onset and at the peak or plateau of the ΔCBF, the value of γ ranged between 0.1 and 0.2. However, after stimulation offset, the value of γ increased to 0.4 primarily because of rapid and slow decays in ΔCBF and ΔCBV, respectively. These results suggest caution in using dynamic measurements of ΔCBF and ΔBOLD required for calculating ΔCMRo2 for functional stimulation, when either ΔCBV has not been accurately measured or a fixed value of γ during hypercapnia perturbation is used.
Localization of the Isthmus in Reentrant Circuits by Analysis of Electrograms Derived from Clinical Noncontact Mapping During Sinus Rhythm and Ventricular Tachycardia
Authors: CIACCIO EDWARD J. , CHOW ANTHONY W. , DAVIES D. WYN , WIT ANDREW L. , PETERS NICHOLAS S.
Published: October 2006

Introduction: New methods for electrogram analysis accurately estimated reentrant circuit isthmus location and shape in a canine model. It was hypothesized that these methods also would locate reentrant circuits causing clinical ventricular tachycardia (VT).

Methods and Results: Intracardiac electrogram recordings, obtained with a noncontact mapping system, were analyzed retrospectively from 14 patients with reentrant VT who had undergone successful radiofrequency ablation for prevention of VT initiation. Unipolar electrograms from 256 uniformly distributed endocardial sites were reconstructed by mathematical transformation. Twenty‐seven tachycardias were mapped; 15 (in 11 patients) had a complete endocardial reentrant circuit with a figure‐of‐eight conduction pattern. During sinus rhythm, the location and axis of the slowest and most uniform conduction in the region of latest endocardial activation (the primary axis), the limits of which were defined as boundaries with >15 ms difference in electrogram duration between contiguous recordings, identified the location and shape of the reentrant circuit isthmus with a mean sensitivity compared with activation mapping of 79.3% and a mean specificity of 97.6%. The midpoint of a theoretical “estimated best ablation line” drawn perpendicular to the primary axis of activation, spanning the estimated isthmus location was within 1.3 ± 0.2 cm (mean distance ± SD) of the actual ablation site that terminated tachycardia. Analysis of VT electrograms, based on time shifts in the far‐field component of the local electrogram when cycle length changed (piecewise linear adaptive template matching [PLATM] method) in 5 of the cases, accurately estimated the time interval between activation at the recording site and the circuit isthmus slow conduction zone where the effective ablation lesion had been placed, which is proportional to the distance between the two locations (mean difference compared with activation mapping: ±37.3 ms).

Conclusion: In selected patients with VT who have a complete endocardial circuit, isthmus location and shape can be discerned by analysis of sinus rhythm or tachycardia electrograms, and an effective ablation site can be predicted without the need to construct activation maps of reentrant circuits. (J Cardiovasc Electrophysiol, Vol. 15, pp. 27‐36, January 2004)
Design of stereoselective Ziegler–Natta propene polymerization catalysts
Authors: Busico Vincenzo , Cipullo Roberta , Pellecchia Roberta , Ronca Sara , Roviello Giuseppina , Talarico Giovanni
Published: October 2006

After five decades of largely serendipitous (albeit formidable) progress, catalyst design in Ziegler–Natta olefin polymerization, i.e., the rational implementation of new active species to target predetermined polyolefin architectures, has ultimately become a realistic ambition, thanks to a much deeper fundamental understanding and major advances in the tools of computational chemistry. In this article, we discuss, as a case history, a unique class of stereorigid
C
2
-symmetric bis(phenoxy-amine)Zr(IV) catalysts with controlled kinetic behavior. A large variety of polypropylene microstructures have been obtained with these catalysts by modulating the steric demand of one key substituent, without altering the nature and symmetry of the ancillary ligand framework, under the guidance of computer modeling. This unusual achievement is relevant
per se
and for the perspective implications in catalyst discovery.
Semicrystalline thermoplastic elastomeric polyolefins: Advances through catalyst development and macromolecular design
Authors: Hotta Atsushi , Cochran Eric , Ruokolainen Janne , Khanna Vikram , Fredrickson Glenn H. , Kramer Edward J. , Shin Yong-Woo , Shimizu Fumihiko , Cherian Anna E. , Hustad Phillip D. , Rose Jeffrey M. , Coates Geoffrey W.
Published: October 2006

We report the design, synthesis, morphology, phase behavior, and mechanical properties of semicrystalline, polyolefin-based block copolymers. By using living, stereoselective insertion polymerization catalysts, syndiotactic polypropylene-block-poly(ethylene-co-propylene)-block-syndiotactic polypropylene and isotactic polypropylene-block-regioirregular polypropylene-block-isotactic polypropylene triblock copolymers were synthesized. The volume fraction and composition of the blocks, as well as the overall size of the macromolecules, were controlled by sequential synthesis of each block of the polymers. These triblock copolymers, with semicrystalline end-blocks and mid-segments with low glass-transition temperatures, show significant potential as thermoplastic elastomers. They have low Young's moduli, large strains at break, and better than 90% elastic recovery at strains of 100% or less. An isotactic polypropylene-block-regioirregular polypropylene-block-isotactic polypropylene-block-regioirregular polypropylene-block-isotactic polypropylene pentablock copolymer was synthesized that also shows exceptional elastomeric properties. Notably, microphase separation is not necessary in the semicrystalline isotactic polypropylenes to achieve good mechanical performance, unlike commercial styrenic thermoplastic elastomers.
Kinetic resolution of racemic α-olefins with
ansa
-zirconocene polymerization catalysts: Enantiomorphic site vs. chain end control
Authors: Byers Jeffery A. , Bercaw John E.
Published: October 2006

Copolymerization of racemic α-olefins with ethylene and propylene was carried out in the presence of enantiopure

C
1

-symmetric
ansa
metallocene, {1,2-(SiMe
2
)
2
(η
5
-C
5
H-3,5-(CHMe
2
)
2
)(η
5
-C
5
H
3
)}ZrCl
2
to probe the effect of the polymer chain end on enantioselection for the
R
- or
S
-α-olefin during the kinetic resolution by polymerization catalysis. Copolymerizations with ethylene revealed that the polymer chain end is an important factor in the enantioselection of the reaction and that for homopolymerization, chain end control generally works cooperatively with enantiomorphic site control. Results from propylene copolymerizations suggested that chain end control arising from a methyl group at the β carbon along the main chain can drastically affect selectivity, but its importance as a stereo-directing element depends on the identity of the olefin.
Nuclearity and cooperativity effects in binuclear catalysts and cocatalysts for olefin polymerization
Authors: Li Hongbo , Marks Tobin J.
Published: October 2006

A series of bimetallic organo-group 4 “constrained geometry” catalysts and binuclear bisborane and bisborate cocatalysts have been synthesized to probe catalyst center–catalyst center cooperativity effects on olefin enchainment in homogenous olefin polymerization and copolymerization processes. Significant nuclearity effects are found versus mononuclear controls, and the effect can be correlated with metal–metal approach distances and ion pairing effects. Novel polymer structures can be obtained by using such binuclear catalyst/cocatalyst systems.
Meisetz and the birth of the KRAB motif
Authors: Birtle Zoë , Ponting Chris P.
Published: October 2006

The largest family of transcription factors in mammals is of Cys2His2 zinc finger-proteins, each with an NH2-terminal KRAB motif. Extensive expansions of this family have occurred in separate mammalian lineages, with ∼400 such genes known in the human genome. Despite their widespread occurrence, the evolutionary provenance of the KRAB motif is unclear since previously it has not been found outside of the tetrapod vertebrates. Here, we show that homologues of the histone methyltransferase Meisetz are present within the sea urchin (Strongylocentrotus purpuratus) genome. Sea urchin and mammalian Meisetz sequences each contain an N-terminal KRAB motif, which thereby establishes an early origin of the KRAB motif prior to the divergence of echinoderm and chordate lineages. Finally, we present evidence that KRAB motifs derive from a novel family of KRI (KRAB Interior) motifs that were present in the last common ancestor of animals, plants and fungi.

Contact:  chris.ponting@anat.ox.ac.uk

Supplementary information: Supplementary data for this article are available at Bioinformatics online.
KGraph: a system for visualizing and evaluating complex genetic associations
Authors: Kelly Reagan J. , Jacobsen Douglas M. , Sun Yan V. , Smith Jennifer A. , Kardia Sharon L. R.
Published: October 2006

Summary: The KGraph is a data visualization system that has been developed to display the complex relationships between the univariate and bivariate associations among an outcome of interest, a set of covariates, and a set of genetic factors, such as single nucleotide polymorphisms (SNPs). It allows for easy viewing and interpretation of genetic associations, correlations among covariates and SNPs, and information about the replication and cross-validation of the associations. The KGraph allows the user to more easily investigate multicollinearity and confounding through visualization of the multidimensional correlation structure underlying genetic associations. It emphasizes gene–environment and gene–gene interaction, both important components of any genetic system that are often overlooked in association frameworks.

Availability:  

Contact:  reagank@umich.edu

Supplementary information: A description of system requirements and a full user manual are available at
Towards a conceptual and operational union of bacterial systematics, ecology, and evolution
Authors: Cohan Frederick M
Published: October 2006

To completely understand the ecology of a bacterial community, we need to identify its ecologically distinct populations (ecotypes). The greatest promise for enumerating a community's constituent ecotypes is held by molecular approaches that identify bacterial ecotypes as DNA sequence clusters. These approaches succeed when ecotypes correspond with sequence clusters, but some models of bacterial speciation predict a one-to-many and others a many-to-one relationship between ecotypes and sequence clusters. A further challenge is that sequence-based phylogenies often contain a hierarchy of clusters and subclusters within clusters, and there is no widely accepted theory to guide systematists and ecologists to the size of cluster most likely to correspond to ecotypes. While present systematics attempts to use universal thresholds of sequence divergence to help demarcate species, the recently developed ‘community phylogeny’ approach assumes no universal thresholds, but demarcates ecotypes based on the analysis of a lineage's evolutionary dynamics. Theory-based approaches like this one can give a conceptual framework as well as operational criteria for hypothesizing the identity and membership of ecotypes from sequence data; ecology-based approaches can then confirm that the putative ecotypes are actually ecologically distinct. Bacterial ecotypes that are demonstrated to have a history of coexistence as ecologically distinct lineages (based on sequence analysis) and as a prognosis of future coexistence (based on ecological differences), are the fundamental units of bacterial ecology and evolution, and should be recognized by bacterial systematics.
The spatial scale of genetic differentiation in a model organism: the wild yeast
Saccharomyces paradoxus
Authors: Koufopanou Vassiliki , Hughes Joseph , Bell Graham , Burt Austin
Published: October 2006

Little information is presently available on the factors promoting genetic divergence in eukaryotic microbes. We studied the spatial distribution of genetic variation in
Saccharomyces paradoxus
, the wild relative of
Saccharomyces cerevisiae
, from the scale of a few centimetres on individual oak trees to thousands of kilometres across different continents. Genealogical analysis of six loci shows that isolates from Europe form a single recombining population, and within this population genetic differentiation increases with physical distance. Between different continents, strains are more divergent and genealogically independent, indicating well-differentiated lineages that may be in the process of speciation. Such replicated populations will be useful for studies in population genomics.