bluuebunny/crossref_metadata_2025 huggingface dataset:
Desigualdade estrutural discreta de membros inferiores é suficiente para causar alteração cinética na marcha de corredores?
Authors: Pereira Carla Sonsino , Sacco Isabel de Camargo Neves
Published: May 2008

Desigualdade de membros inferiores (DMI) está presente em cerca de 70% da população geral, podendo ser do tipo estrutural onde existe diferença no comprimento de estruturas ósseas, ou funcional, como resultado de alterações mecânicas dos membros inferiores. A desigualdade pode ainda ser classificada quanto a sua magnitude, sendo discreta, moderada, ou grave. As desigualdades discretas têm sido associadas especificamente à fratura por estresse, dor lombar e osteoartrite, e quando uma desigualdade está presente em indivíduos cuja sobrecarga mecânica é acentuada pela sua prática profissional, diária ou recreativa, estas alterações ortopédicas podem se manifestar precoce e gravemente. O objetivo deste estudo foi analisar e comparar a força reação do solo (FRS) durante a marcha de corredores com e sem DMI discreta. Os resultados mostraram que os sujeitos com desigualdades de 0,5 a 2,0 cm apresentaram no membro menor maiores valores da força vertical mínima (0,57 ± 0,07 PC) em relação ao membro maior (0,56 ± 0,08 PC). Logo, sujeitos com DMI discreta adotam mecanismos compensatórios capazes de gerar sobrecarga adicional ao sistema musculoesquelético para promover uma marcha simétrica como demonstrado pelos valores do Índice de Simetria Absoluto das variáveis da FRS vertical e horizontal.
Estabilidade articular do joelho no quadro do "joelho-flutuante"
Authors: Marco Felipe Antônio de , Rozim Alessandro Zorzi , Piedade Sérgio Rocha
Published: May 2008

Neste trabalho, 22 pacientes com fraturas ipslaterais do fêmur e da tíbia ("joelho flutuante") tratados cirurgicamente foram convocados para reavaliação. Com seguimento mínimo de 4 meses, 17 pacientes compareceram e foram reavaliados através de exame físico, radiológico, escala de Lysholm e o escore de Kärlstron. As fraturas foram classificadas quanto ao grau de exposição (Gustillo e Andersen), cominuição (AO) e o "joelho-flutuante" (Fraser). Doze pacientes (70,6%) apresentaram alterações objetivas no exame físico do joelho. A instabilidade articular foi a alteração mais encontrada, presente em oito casos (47%), seguida da restrição de movimento em sete pacientes (41,2%). A instabilidade anterior foi diagnosticada em cinco casos (29,4%), sendo três associados à instabilidade em varo. A instabilidade posterior estava presente em dois pacientes (11,8%), ambos associados com instabilidade em varo. Um paciente apresentou instabilidade periférica em varo e valgo, associada à restrição importante da flexão do joelho. As presença de fraturas intra-articulares, fraturas expostas do fêmur cursaram com maior incidência de restrição do arco de movimento. Nesta casuística os resultados obtidos reforçam a necessidade da avaliação sistemática da estabilidade articular do joelho, visto que o quadro de "joelho flutuante" está freqüentemente associado à lesão cápsulo-ligamentar desta articulação.
Reproduction of Oligosarcus hepsetus (Cuvier, 1829) (Characiforms) in the Serra do Mar State Park, São Paulo, Brazil
Authors: Gomiero LM. , Garuana L. , Braga FMS.
Published: May 2008

The purpose of this study was to characterize the reproduction of Oligosarcus hepsetus in the Grande river (Santa Virginia Unit - Serra do Mar State Park) based on the reproductive period, length of first gonadal maturation for both sexes, sexual proportion, oocyte development, type of spawn and fecundity. The Grande river was sampled monthly from January through December 2004. The numerical frequency of the stages of maturity and the volumetric method were utilized to determine the reproductive period and fecundity, respectively. The reproduction of Oligosarcus hepsetus was characterized by a long period, relatively low fecundity, precocious length of first gonadal maturation and parceled spawning.
Utilização de contratos futuros agropecuários no perfil médio de investimentos dos fundos de pensão no Brasil
Authors: Costa Thiago de Melo Teixeira da , Piacenti Carlos Alberto
Published: May 2008

Os Fundos de Pensão têm se tornado cada vez mais representativos no cenário mundial. A sustentabilidade dessas instituições exige um eficiente processo de gerenciamento de suas carteiras de investimento. Ao mesmo tempo, as negociações com contratos futuros agropecuários vêm se consolidando no Brasil e surgem como uma alternativa para investidores que queiram diversificar suas carteiras. O objetivo deste trabalho foi avaliar a viabilidade da utilização de derivativos agropecuários como forma de minimização de riscos em carteiras de investimentos de Fundos de Pensão no Brasil, dentro dos limites legais aos quais essas entidades estão sujeitas, tomando como referência o perfil médio dessas instituições no país com relação à alocação de seus investimentos. Para isso, avaliou-se o desempenho de carteiras sem e com 1% de seus investimentos em derivativos agropecuários. As análises de risco foram feitas através do modelo Value-at-risk (VaR), utilizando modelos de variância condicional para a extração da série diária de volatilidades. Os retornos foram ponderados pelo risco, através do Índice de Sharpe Adaptado (ISA). Os resultados mostraram que, dentro dos parâmetros estabelecidos para cada modalidade de investimento, a introdução de contratos futuros agropecuários foi benéfica, reduzindo o risco mais que proporcionalmente ao retorno. O trabalho torna-se mais significativo à medida que se analisam os montantes financeiros envolvidos. Considerando, por exemplo, que os Fundos de Pensão invistam, de forma geral, 1% de seus ativos, seriam injetados, no mercado futuro de commodities agropecuárias, mais de R$ 2 bilhões, valor que representa, dentro da movimentação financeira de 2004, aproximadamente 10% de todos os recursos investidos.
Selective oestrogen receptor (ER) modulators reduce microglia reactivity in vivo after peripheral inflammation: potential role of microglial ERs
Authors: Tapia-Gonzalez Silvia , Carrero Paloma , Pernia Olga , Garcia-Segura Luis M , Diz-Chaves Yolanda
Published: May 2008

It has been previously reported that the neuroprotective hormone oestradiol reduces microglia inflammatory activity. The objective of this study was to test whether two selective oestrogen receptor modulators, tamoxifen and raloxifene, modulate in vivo the activation of microglia induced by the peripheral administration of lipopolysaccharide (LPS). Activation of microglia was assessed in the white matter of the cerebellum using immunoreactivity for major histocompatability complex-II. Oestradiol, tamoxifen and raloxifene decreased microglia activation induced by LPS in male and ovariectomized female rats, although the doses of oestradiol that were effective in decreasing microglia reactivity were not the same in both sexes. Tamoxifen reduced microglia activation in all experimental groups at all doses tested (0.5–2 mg/kg b.w.) while raloxifene lost its anti-inflammatory activity at the higher dose tested (2 mg/kg b.w). In addition, raloxifene had per se a moderate pro-inflammatory activity in the brain of control female rats and its anti-inflammatory activity was partially impaired in female animals after 1 month of deprivation of ovarian hormones. Spots of oestrogen receptor (ER)-α immunoreactivity were detected in the soma and cell processes of microglia. Treatment with LPS, oestradiol or tamoxifen induced an increase of ER-α immunoreactive spots in the perikaryon of microglia, while oestradiol antagonized the effect of LPS. The results indicate that some oestrogenic compounds decrease brain inflammation by a mechanism that may involve ERs expressed by microglia. The findings support the potential therapeutic role of oestrogenic compounds as protective anti-inflammatory agents for the central nervous system.
High-rate anaerobic wastewater treatment: diversifying from end-of-the-pipe treatment to resource-oriented conversion techniques
Authors: van Lier Jules B.
Published: May 2008

Decades of developments and implementations in the field of high-rate anaerobic wastewater treatment have put the technology at a competitive level. With respect to sustainability and cost-effectiveness, anaerobic treatment has a much better score than many alternatives. Particularly, the energy conservation aspect, i.e. avoiding the loss of energy for destruction of organic matter, while energy is reclaimed from the organic waste constituents in the form of biogas, was an important driver in the development of such systems. Invoked by the present greenhouse alert, the energy involved is nowadays translated into carbon credits, providing another incentive to further implement anaerobic technology. Anaerobic conversion processes, however, offer much more than cost-effective treatment systems. Selective recovery of metals, effective desulphurization, recovery of nutrients, reductive detoxification, and anaerobic oxidation of specific compounds are examples of the potentials of anaerobic treatment. This paper presents a survey on the state of the art of full-scale anaerobic high-rate treatment of industrial wastewaters and highlights current trends in anaerobic developments.
Analysis of microbial community structure and diversity in the thermophilic anaerobic digestion of waste activated sludge
Authors: Kobayashi T. , Li Y. Y. , Harada H.
Published: May 2008

The microbial community structures in the thermophilic anaerobic digestion (TAD) of waste activated sludge (WAS) and WAS were analyzed with molecular biological techniques including real-time polymerase chain reaction (PCR) and cloning. The microbial community of TAD had less diversity than that of WAS, and the sequences obtained in WAS were not present in TAD by the cloning analysis. In the TAD bacterial clone library, 97.5% of total clones were affiliated with the phylum Firmicutes and 73.1% with the genus Coprothermobacter. Real-time PCR and cloning analysis revealed that the number of Methanosarcina thermophila, which is an acetoclastic methanogen, is larger than that of Methanoculleus thermophilus, which is a hydrogenotrophic methanogen, in terms of the numbers of copies of 16S ribosomal DNA (rDNA).
On-line titrimetric monitoring of anaerobic–anoxic EBPR processes
Authors: Vargas M. , Guisasola A. , Lafuente J. , Casas C. , Baeza J. A.
Published: May 2008

Denitrifying phosphorus accumulating organisms (DPAO) are able to remove nitrogen and phosphorus simultaneously. The use of DPAO in EBPR systems results in a substantial saving on aeration cost and a lower sludge production when compared to anaerobic–aerobic EBPR systems. This process is usually studied in sequencing batch reactors (SBR) and monitored with off-line measurements. However, off-line monitoring implies low frequency data sampling and delay between sampling and obtainment of the results. For this reason, an online measurement such as titrimetry is strongly recommended to improve the daily management of the lab-scale SBR. This paper shows different applications of titrimetric measurements for on-line monitoring of DPAO lab-scale SBR cycles. The results demonstrate that titrimetry is a suitable tool for detecting the end of phosphorus release and carbon substrate depletion point in the anaerobic phase. Moreover, this paper proposes the indirect measurement of nitrate/nitrite uptake rate with titrimetric measurements, which allows the on-line estimation of its concentration during the anoxic phase. Therefore, titrimetry is an on-line measurement with a high potential to implement new control strategies in DPAO lab-scale SBR systems.
Application of heat shock protein assay and proteome assay to water from wastewater treatment plant
Authors: Funamizu Naoyuki , Takenaka Mikako , Han Junkyu , Isoda Hiroko
Published: May 2008

In this study we applied bioassay using Chinese hamster ovary (CHO) cells with a heat shock protein (HSP) 47 promoter to the effluent of the wastewater treatment plants in Sapporo and we observed the statistically significant HSP production. This implied the effluent contained some organic matter which can stress the CHO cells. To investigate the possible causes of the toxicity of the effluent, we applied the assay to the rejected water from the sludge treatment plant, the mixtures of sewage and rejected water. The evolution of HSP production during the aerobic decay process and thickening process of sludge was also examined. These assay results showed that dissolved microbial products generated and/or released from activated sludge during its decay process in the aeration tank and during thickening and dewatering process in the sludge treatment train contributed to develop HSP production. The proteomics analysis was also applied to the effluent and detected the production of elongation factor 1β. This result implies that the effluent from wastewater treatment plants may cause changes in cell proteins involved in allergic reaction.
The first introduction of reclaimed wastewater to dry-farming field in Okinawa Island, Japan
Authors: Shigematsu T. , Dayanthi W. K. C. N. , Yamashita N. , Tanaka H. , Yamashita T.
Published: May 2008

Reclaimed wastewater (RWW) will be introduced to the first large-scale irrigation project for dry-farming on Okinawa Island, Japan. The wastewater reclamation for agricultural use sounds attractive to the water resource management. Since there are no specific standards for the RWW irrigation, the monitoring and other demonstrative experiments have been conducted using the experimental reclamation facility, which is based on the criteria “Title22”. The experiments showed that the existing system is sufficient to meet the above criteria of pathogens, protozoa and viruses, and the concentrations of hazardous chemicals are lower than the environmental standards in Japan. In addition, several laboratory soil column experiments were conducted to address the environmental issues. An increase of denitrification due to the continuous irrigation was observed. Salt and nitrate accumulation in the surface soil was observed as well. We can conclude that the RWW of the above facility assures the safety for human health, and further research based on environmental issues is needed in addition to an integrated risk assessment and communication.
Pesticides in groundwater and drinking water wells: overview of the situation in the Netherlands
Authors: Schipper P. N. M. , Vissers M. J. M. , van der Linden A. M. A
Published: May 2008

In the Netherlands, many of the fresh groundwater resources are vulnerable to pollution. Owing to high population densities and intensive farming practices, pesticide residues are found in groundwater at many places. Hence a number of drinking water abstraction wells contain pesticides residues, causing considerable costs for purification. The Water Framework Directive (WFD) requires countries to assess the chemical status of groundwater bodies and set up monitoring plans for groundwater quality, including pesticides. 771 groundwater samples were taken from monitoring wells in 2006 and analysed for a broad list of pesticides in order to fulfil these requirements. Pesticide were detected in 27% of samples, while in 11% the WFD limit of 0.1 μg/l was exceeded. In this paper, these and earlier measurements are evaluated further, considering also measurements in drinking water wells, information about the origin of measured pesticides and calculated trends in use and emissions. The measurements in the monitoring wells showed that where pesticides are used, 15–55% (minimal and maximal estimation) of the wells in shallow groundwater (1 to 20m below soil surface) contain pesticides residues at concentrations above 0.1 μg/l. When the metabolites BAM and AMPA are excluded (as not relevant in human toxicological terms), the estimation range is 7–37%. These patterns observed in shallow groundwater are reflected by the occurrence of pesticides in vulnerable abstraction wells that are used for the production of drinking water. The WFD requires the determination of both status and trends. The design of current monitoring network is evaluated from this perspective. Several recommendations are made for more adequate and efficient monitoring.
Is Earnings Fraud Associated with High Deferred Tax and/or Book Minus Tax Levels?
Authors: Ettredge Michael L. , Sun Lili , Lee Picheng , Anandarajan Asokan A.
Published: May 2008

The objective of this paper is to provide preliminary evidence whether SFAS No. 109 tax data might be useful in distinguishing between firms that do versus do not engage in earnings overstatement fraud (hereafter fraud). We examine the associations of various versions of deferred tax expense (DTE) variables and book income minus taxable income (BMT) variables with fraud, in the year of fraud onset and the year prior to fraud. The analysis is based upon a sample of 65 firms with positive pretax income, sanctioned by the Securities and Exchange Commission (SEC), in Accounting and Auditing Enforcement Releases (AAERs). A set of control firms are matched by asset size, two-digit SIC code, year, and nature of income (positive versus negative pretax income). We also perform analyses using a larger, nonmatched control sample. Our results indicate that, for firms with positive pretax income, DTE-based variables have strong incremental associations with fraud occurrence, beyond discretionary accruals and selected other explanatory variables, in the year of fraud onset. DTE-based variables have modest incremental power to explain future (next-year) fraud occurrence (but only when using matched samples). BMT-based variables generally lack explanatory power. In summary, this study provides new information about managers' tax reporting behavior in the presence of fraud, and suggests that DTE-based variables are likely to be useful in detecting fraud.
Economic Incentives for Voluntary Reporting on Internal Risk Management and Control Systems
Authors: Deumes Rogier , Knechel W. Robert
Published: May 2008

This paper investigates managers' economic incentives for voluntary reporting on risk management and internal control using a sample of publicly traded firms in The Netherlands in the late 1990s. In this particular setting, internal control reporting was voluntary and covered a wide business-based approach as defined in key internal control frameworks. We create an index to measure the extent of disclosure by identifying six reportable items related to internal control. Regarding managers' incentives to report, we hypothesize that voluntary disclosure increases with the extent of information and agency problems, as proxied by management and block holder ownership and financial leverage. Supporting our hypotheses, we find a negative relationship between the extent of internal control disclosure and management and block holder ownership, and positive relationship between the extent of disclosure and financial leverage. We interpret these findings as evidence for a conscious trade-off by managers, which is linked to the costs and benefits of making internal control disclosures. Additionally, we find some evidence that the extent of disclosure varies with firms' inherent risk exposure, as proxied by a number of firm operating characteristics. One implication of our findings is that regulators may wish to allow firms flexibility in their internal control reporting choice, as firms take a broad approach to internal control that goes beyond SOX-based regulations, and tailor their internal control reports to suit their specific environments.
Molecular Pathology of Nephrotic Syndrome in Childhood: A Contemporary Approach to Diagnosis
Authors: Liapis Helen
Published: May 2008

Molecular and genetic studies in the last 2 decades have shed new light on the understanding of congenital and infantile nephrotic syndrome (NS). Glomerular pathology may appear as minimal change disease, focal segmental glomerulosclerosis, or diffuse mesangial sclerosis, glomerular diseases now recognized as podocyte injuries and in part caused by altered podocyte genes. Even though genetic mutations are not implicated in all infants with NS, the study of familial disease and congenital NS reveals that proteinuria is in many patients due to specific gene mutations. The most common mutations are in 4 genes, 3 of which are podocyte genes: NPHS1 (Finnish nephropathy), NPHS2 (podocin-induced focal segmental glomerulosclerosis), WT1 (diffuse mesangial sclerosis), and LAMB2 (Pierson syndrome). Furthermore, these studies have improved our understanding of steroid-resistant NS in older children, particularly girls, in whom proteinuria may be due to WT1 mutations. Availability of molecular genetic testing and antibodies to specific gene products are closing the gap between histopathology of pediatric glomerular disease and molecular genetic diagnosis. Recognition of NS variants, which may be reversible (eg, mitochondrial mutations, viral disease), is important. This review discusses the most common entities and the differential diagnosis of pediatric NS from the pathologist's point of view, with an emphasis on congenital (<3 months) and infantile (3 months to 1 year) NS in light of molecular and genetic studies.
Effects of Chemotherapy during Pregnancy on the Placenta
Authors: Abellar Rosanna G. , Pepperell John R. , Greco David , Gundogan Fusun , Kostadinov Stefan , Schwartz Joanna , Tantravahi Umadevi , De Paepe Monique E.
Published: May 2008

Whereas the effects of chemotherapy during pregnancy for mother and fetus are well described, its effects on the placenta remain largely undetermined. We performed a retrospective clinicopathologic analysis of the placenta following chemotherapy. Charts were reviewed for type of malignancy, type and timing of chemotherapy, and fetal and pregnancy outcome. Placentas were studied by standard pathologic analysis as well as computer-assisted morphometry and fluorescence in situ hybridization (FISH) analysis. Patients ( n = 13) underwent chemotherapy during pregnancy for carcinoma of breast (3), ovary (2), cervix (2), salivary gland (1), lymphoma/leukemia (4), or rhabdomyosarcoma (1). Eleven patients were treated with DNA-active cytotoxic agents during the 2nd and/or 3rd trimesters; their placentas showed nonspecific findings, including villous hypermaturity, distal villous hypoplasia, villous edema, and excessive extravillous trophoblast, and 4/11 (36%) were small-for-age. In one case (rhabdomyosarcoma), the mother was exposed to cytotoxic agents throughout the entire pregnancy. In this case, associated with severe congenital anomalies, the placenta showed striking nuclear pleomorphism of the extravillous trophoblast of the chorion laeve, associated with FISH-demonstrated hyperpolyploidy. One patient was treated with the targeted tyrosine kinase inhibitor, imatinib, in 2 consecutive pregnancies; these placentas showed no specific anomalies. Our findings suggest that chemotherapy during the 1st trimester induces excessive polyploidization of the chorion laeve trophoblast, likely representing an adaptive response to intraamniotic toxins. Second and 3rd trimester exposure to cytotoxic agents may predispose to placental underdevelopment. However, without appropriate controls (untreated patients with equivalent malignancies), the specific effects of chemotherapy in this group are difficult to assess.
Lipid changes occuring in the course of hematological cancers
Authors: Kuliszkiewicz-Janus Małgorzata , Małecki Rafał , Mohamed Abdulrahman
Published: May 2008

The relationship between plasma lipid levels and mortality from cardiovascular diseases has been shown in many studies, but there has been far less investigation into their relationship to non-cardiovascular diseases. The aim of this study was to investigate the lipid profile of individuals with hematological malignancies and its relationship to disease activity. 238 patients were included in the study: 84 with acute leukemia, 62 with non-Hodgkin lymphoma, 35 with Hodgkin’s lymphoma, 32 with multiple myeloma, and 25 with myeloproliferative syndrome. The HDL cholesterol level of the patients differed to that of the individuals in the control group in the active disease period for all the analyzed disorders, but only remained statistically significant in the acute leukemia and non-Hodgkin lymphoma groups during the remission period. Smaller differences were observed for the remaining lipid fractions, except for the triglyceride level, which increased in the active disease period in all the analyzed disorders except non-Hodgkin lymphoma. The most pronounced changes in the lipid fractions occurred in the HDL cholesterol level, and were the most remarkable for acute leukemia.
Hydrogen peroxide as a potential mediator of the transcriptional regulation of heparan sulphate biosynthesis in keratinocytes
Authors: Nakayama Fumiaki , Hagiwara Akiko , Yamamoto Tetsuo , Akashi Makoto
Published: May 2008

Ionizing radiation is one of the types of oxidative stress that has a number of damaging effects on cutaneous tissues. One of the histological features of radiation-induced cutaneous fibrosis is the accumulation of extracellular matrix (ECM) components, including heparan sulfate proteoglycan (HSPG), which are required for the repair of tissue damage, and operate by interacting with a variety of growth factors. In this study, we established a model of human HaCaT keratinocytes overexpressing anti-oxidative enzyme genes to elucidate the mechanism of oxidative stress leading to the accumulation of HSPG and the role of its accumulation. Catalase overexpression induced an increase in anti-HS antibody (10E4) epitope expression in these cells. Western blotting showed that the smeared bands of HSPG were obviously shifted to a higher molecular weight in the catalase transfectants due to glycosylation. After heparitinase I treatment, the core proteins of HSPG were expressed in the catalase transfectants to almost the same extent as in the control cells. In addition, the transcript levels of all the enzymes required for the synthesis of the heparan sulfate chain were estimated in the catalase transfectant clones. The levels of five enzyme transcripts — xylosyltransferase-II (XT-II), EXTL2, D-glucuronyl C5-epimerase (GLCE), HS2-O-sulfotransferase (HS2ST), and HS6-O-sulfotransferase (HS6ST) — were significantly increased in the transfectants. Moreover, hydrogen peroxide was found to down-regulate the levels of these enzymes. By contrast, siRNA-mediated repression of catalase decreased 10E4 epitope expression, the transcript level of HS2ST1, and the growth rate of HaCaT cells. These findings suggested that peroxide-mediated transcriptional regulation of HS metabolism-related genes modified the HS chains in the HaCaT keratinocytes.
Optical modelling of a Si-based DBR laser source using a nanocrystal Si-sensitized Er-doped silica rib waveguide in the C-band
Authors: Ciminelli C. , Frascella P. , Armenise M. N.
Published: May 2008

The availability of reliable silicon-based laser sources is at the basis of the integration of photonic and microelectronic devices on a single chip with consequent development of wavelength division multiplexing telecommunication systems.

A high efficiency Si-based laser source with good stability at room temperature would encourage and push the large scale of integration of electronic and photonic devices within a single chip.

Several techniques have been proposed for generating light with an internal quantum efficiency some order of magnitude greater than that typical of silicon (10−6) by using either electrical or optical pumping. Among them we mention the improvement of some fabrication process steps, reduction of the channels of non-radiative recombination, quantum confinement, the use of silicon nanocrystals (Si-ncs) incorporated in a silica matrix. This last technique is used in combination with Er3+ doping to generate light emission around 1500 nm in silicon, since Er-doped Si-ncs behave as electron-hole pairs trap, and the presence of Er shifts the emission peak to around 1500 nm.

In this paper we have pointed out the optical model of a Si-based DBR laser including a Si-ncs Er-doped SiO2 rib waveguide, working at a wavelength in C-band. In particular, after a brief description of the structural and optical properties of the silicon crystals, we report on the model and design of the Er:Si-nc/SiO2 rib waveguide, of the optical cavity and of the Bragg mirrors.
Flops Connect Minimal Models
Authors: Kawamata Yujiro
Published: May 2008

A result by Birkar-Cascini–Hacon–McKernan together with the boundedness of length of extremal rays implies that diﬀerent minimal models can be connected by a sequence of ﬂops.
Human activity facilitates altitudinal expansion of exotic plants along a road in montane grassland, South Africa
Authors: Kalwij Jesse M. , Robertson Mark P. , van Rensburg Berndt J.
Published: May 2008

Question: Do anthropogenic activities facilitate the distribution of exotic plants along steep altitudinal gradients?

Location: Sani Pass road, Grassland biome, South Africa.

Methods: On both sides of this road, presence and abundance of exotic plants was recorded in four 25‐m long road‐verge plots and in parallel 25 m x 2 m adjacent land plots, nested at five altitudinal levels: 1500, 1800, 2100, 2400 and 2700 m a.s.l. Exotic community structure was analyzed using Canonical Correspondence Analysis while a two‐level nested Generalized Linear Model was fitted for richness and cover of exotics. We tested the upper altitudinal limits for all exotics along this road for spatial clustering around four potential propagule sources using a t‐test.

Results: Community structure, richness and abundance of exotics were negatively correlated with altitude. Greatest invasion by exotics was recorded for adjacent land at the 1500 m level. Of the 45 exotics, 16 were found at higher altitudes than expected and observations were spatially clustered around potential propagule sources.

Conclusions: Spatial clustering of upper altitudinal limits around human inhabited areas suggests that exotics originate from these areas, while exceeding expected altitudinal limits suggests that distribution ranges of exotics are presently underestimated. Exotics are generally characterised by a high propagule pressure and/or persistent seedbanks, thus future tarring of the Sani Pass may result in an increase of exotic species richness and abundance. This would initially result from construction‐related soil disturbance and subsequently from increased traffic, water run‐off, and altered fire frequency. We suggest examples of management actions to prevent this.
NUMERICAL ANALYSIS OF LASING DYNAMICS IN VOLUME FREE ELECTRON LASER
Authors: Sytova Svetlana
Published: May 2008

Nonlinear phenomena originating in volume free electron laser (VFEL) are investigated by methods of mathematical modelling using computer code VOLC. It was demonstrated the possibility of excitation of quasiperiodic oscillations not far from threshold values of electron beam current density and VFEL resonator length. It was investigated sensibility of numerical solution to initial conditions for different VFEL regimes of operation. Parametric maps with respect to electron beam current and detuning from synchronism condition present complicated root to chaos with windows of periodicity in VFEL. Investigation of chaotic lasing dynamics in VFEL is important in the light of experimental development of VFEL in Research Institute for Nuclear Problems.
UNCERTAINTY PRINCIPLES FOR THE KONTOROVICH‐LEBEDEV TRANSFORM
Authors: Yakubovich Semyon B.
Published: May 2008

By using classical uncertainty principles for the Fourier transform and composition properties of the Kontorovich‐Lebedev transform, analogs of the Hardy, Beurling, Cowling‐Price, Gelfand‐Shilov and Donoho‐Stark theorems are obtained.
MULTIPLE SOLUTIONS OF THE BVB FOR TWO‐DIMENSIONAL SYSTEM BY EXTRACTING LINEAR PARTS AND QUASILINEARIZATIO
Authors: Yermachenko Inara
Published: May 2008

We investigate a two-dimensional differential system of the form x' = f(t, y), y' = h(t, x) together with the boundary conditions x(0) = 0, x(1) = 0 by using the quasilinearization process. We show that if this problem allows for quasilinearization with respect to essentially different linear parts, then it has multiple solutions.
Oogenesis: Prospects and challenges for the future
Authors: Rodrigues P. , Limback D. , McGinnis L.K. , Plancha C.E. , Albertini D.F.
Published: May 2008

Oogenesis serves a singular role in the reproductive success of plants and animals. Of their remarkable differentiation pathway what stands out is the ability of oocytes to transform from a single cell into the totipotent lineages that seed the early embryo. As our understanding that commonalities between diverse organisms at the genetic, cellular and molecular levels are conserved to achieve successful reproduction, the notion that embryogenesis presupposes oogenesis has entered the day‐to‐day parlance of regenerative medicine and stem cell biology. With emphasis on the mammalian oocyte, this review will cover (1) current concepts regarding the birth, survival and growth of oocytes that depends on complex patterns of cell communication between germ line and soma, (2) the notion of “maternal inheritance” from a genetic and epigenetic perspective, and (3) the relative value of model systems with reference to current clinical and biotechnology applications. J. Cell. Physiol. 216: 355–365, 2008. © 2008 Wiley‐Liss, Inc.
New sources of γ‐linolenic acid
Authors: Wolf R. B. , Kleiman R. , England R. E.
Published: May 2008

γ‐Linolenic acid (18:3Δ6,9,12) occurs in significant amounts in various species of plants surveyed. Of the species analyzed in this study, Nonnea macrospernia, with 5.1% 7‐linolenic acid in the seed, is the richest source of this fatty acid. Other species in the same family (Boraginaceae) are also good sources: Adelocaryum coelestinum, Alkanna froedinii, Alkanna orientalis and Brunnera orientalis. Scrophularia marilandica (family Scrophulariaceae) seeds contain 37.9% oil, of which 9.6% is γ‐linolenic acid. All species mentioned above are better sources, when the total amount of γ‐linolenic acid in the seed is considered, than that used traditionally, Evening Primrose (Oenothera biennis, family Onagraceae). None of the other Onagraceae nor any of the Ribes (family Saxifragaceae) species analyzed are as rich in γ‐linolenic acid as Evening Primrose. Octadecatetraenoic acid (18:4Δ,6,9,12,15) was found in significant amounts in most of the Boraginaceae and Ribes surveyed. The Onagraceae and Scrophulariaceae lack detectable amounts of this fatty acid.
Chemical composition of acacia seeds
Authors: Chowdhury A. R. , Banerji R. , Misra G. , Nigam S. K.
Published: May 2008

Several plants of Acacieae (family Leguminosae) have been recommended under aforestation programs. The seeds of some such plants have been examined for their fatty acid composition with special reference to epoxy acids. Epoxy 18:1 in Acacia auriculiformis, A. catechu, A. coriacea and A. mellifera was 4.9, 0.1, 2.1, and 0.6%,respectively.
Petrology and geochemistry of cross‐chains in the Izu‐Bonin back arc: Three mantle components with contributions of hydrous liquids from a deeply subducted slab
Authors: Machida Shiki , Ishii Teruaki , Kimura Jun‐Ichi , Awaji Shunsaku , Kato Yasuhiro
Published: May 2008

Detailed petrological and geochemical analyses of volcanic rocks from back‐arc en echelon seamounts, consisting of four cross‐chains in the Izu‐Bonin back arc, provide insights into the origin of complex magma types for back‐arc volcanism associated with back‐arc spreading in an oceanic arc environment. The sampled volcanic rocks are classified into three distinct rock suites on the basis of trace element characteristics: an “Enriched Suite” with enriched trace element compositions and high Nb/Zr (0.075–0.10); a “Less Enriched Suite” with depleted high‐field‐strength elements (HFSEs), lower Nb/Zr (0.03–0.075), and enriched large ion lithophile elements (LILEs) and light rare earth elements (LREEs); and a “Depleted Suite” with very depleted HFSEs, the lowest Nb/Zr (<0.03), and slightly enriched LILEs and LREEs. Estimated primary melt compositions of each suite and numerical open‐system melting models for trace elements indicate that different HFSE ratios and abundances in primary magmas for the three suites cannot be explained solely by differences in degree of melting or subduction inputs via slab melting and dehydration. Our results indicate the following: (1) 15% partial melting of source mantle for Shikoku Basin basalt and an influx of fluid‐mobile‐element‐poor supercritical liquid, amounting to 0.075% of the source mantle, from residual (predehydrated) subducted slab material can reproduce the geochemistry of the Less Enriched Suite primary melt. (2) The residual (depleted) mantle, derived from melt extraction by back‐arc basin opening and/or previous Less Enriched Suite volcanism, cannot be source mantle for Depleted Suite lavas, which require a distinct mantle source that is more depleted in trace elements (especially Nb and Ta) than >2σ depleted mid‐ocean ridge basalt mantle (D‐DMM). (3) Source mantle for Enriched Suite rocks is distributed independently beneath the Izu‐Bonin back‐arc region. (4) Less Enriched Suite magmas erupted in all seamount chains, indicating that these magmas constitute the major volcanic component of back‐arc cross‐chain volcanism in the northern Izu‐Bonin arc. We conclude that three distinct mantle sources with various contributions from a deeply subducted slab exist beneath the cross‐chains in the Izu‐Bonin back arc.
Rapid, precise, and high‐sensitivity acquisition of paleomagnetic and rock‐magnetic data: Development of a low‐noise automatic sample changing system for superconducting rock magnetometers
Authors: Kirschvink Joseph L. , Kopp Robert E. , Raub Timothy D. , Baumgartner Christopher T. , Holt John W.
Published: May 2008

Among Earth sciences, paleomagnetism is particularly linked to the statistics of large sample sets as a matter of historical development and logistical necessity. Because the geomagnetic field varies over timescales relevant to sedimentary deposition and igneous intrusion, while the fidelity of recorded magnetization is modulated by original properties of rock units and by alteration histories, “ideal” paleomagnetic results measure remanent magnetizations of hundreds of samples at dozens of progressive demagnetization levels, accompanied by tests of magnetic composition on representative sister specimens. We present an inexpensive, open source system for automating paleomagnetic and rock magnetic measurements. Using vacuum pick‐and‐place technology and a quartz‐glass sample holder, the system can in 1 h measure remanent magnetizations, as weak as a few pAm2, of ∼30 specimens in two vertical orientations with measurement errors comparable to those of the best manual systems. The system reduces the number of manual manipulations required per specimen approximately eightfold.
Nonlinear force‐free coronal magnetic field extrapolation scheme based on the direct boundary integral formulation
Authors: He Han , Wang Huaning
Published: May 2008

The boundary integral equation (BIE) method was first proposed by Yan and Sakurai (2000) and used to extrapolate the nonlinear force‐free magnetic field in the solar atmosphere. Recently, Yan and Li (2006) improved the BIE method and proposed the direct boundary integral equation (DBIE) formulation, which represents the nonlinear force‐free magnetic field by direct integration of the magnetic field on the bottom boundary surface. On the basis of this new method, we devised a practical calculation scheme for the nonlinear force‐free field extrapolation above solar active regions. The code of the scheme was tested by the analytical solutions of Low and Lou (1990) and was applied to the observed vector magnetogram of solar active region NOAA 9077. The results of the calculations show that the improvement of the new computational scheme to the scheme of Yan and Li (2006) is significant, and the force‐free and divergence‐free constraints are well satisfied in the extrapolated fields. The calculated field lines for NOAA 9077 present the X‐shaped structure and can be helpful for understanding the magnetic configuration of the filament channel as well as the magnetic reconnection process during the Bastille Day flare on 14 July 2000.
Electron density estimations derived from spacecraft potential measurements on Cluster in tenuous plasma regions
Authors: Pedersen A. , Lybekk B. , André M. , Eriksson A. , Masson A. , Mozer F. S. , Lindqvist P.‐A. , Décréau P. M. E. , Dandouras I. , Sauvaud J.‐A. , Fazakerley A. , Taylor M. , Paschmann G. , Svenes K. R. , Torkar K. , Whipple E.
Published: May 2008

Spacecraft potential measurements by the EFW electric field experiment on the Cluster satellites can be used to obtain plasma density estimates in regions barely accessible to other type of plasma experiments. Direct calibrations of the plasma density as a function of the measured potential difference between the spacecraft and the probes can be carried out in the solar wind, the magnetosheath, and the plasmashere by the use of CIS ion density and WHISPER electron density measurements. The spacecraft photoelectron characteristic (photoelectrons escaping to the plasma in current balance with collected ambient electrons) can be calculated from knowledge of the electron current to the spacecraft based on plasma density and electron temperature data from the above mentioned experiments and can be extended to more positive spacecraft potentials by CIS ion and the PEACE electron experiments in the plasma sheet. This characteristic enables determination of the electron density as a function of spacecraft potential over the polar caps and in the lobes of the magnetosphere, regions where other experiments on Cluster have intrinsic limitations. Data from 2001 to 2006 reveal that the photoelectron characteristics of the Cluster spacecraft as well as the electric field probes vary with the solar cycle and solar activity. The consequences for plasma density measurements are addressed. Typical examples are presented to demonstrate the use of this technique in a polar cap/lobe plasma.
Cluster observations of “crater” flux transfer events at the dayside high‐latitude magnetopause
Authors: Owen C. J. , Marchaudon A. , Dunlop M. W. , Fazakerley A. N. , Bosqued J.‐M. , Dewhurst J. P. , Fear R. C. , Fuselier S. A. , Balogh A. , Rème H.
Published: May 2008

On 11 January 2002 Cluster detected two “crater”‐like flux transfer event (FTE) signatures. The four spacecraft were in quasi‐linear formation, spread over ∼2 RE in the magnetopause normal direction, and sample a range of distances from it. The observations occur near a southward turning of the IMF, but no solar wind pressure pulses are detected. Analysis reveals: (1) C3, closest to the magnetopause, made two transient excursions into the magnetosheath which bracket two “crater”‐FTE signatures detected at the other three spacecraft; (2) magnetic field deflections observed at the other spacecraft do not match the magnetosheath field direction at C3; (3) these FTE signatures involve encounters with reconnected field lines and associated boundary layers lying just inside the magnetopause, including a “separatrix layer” of accelerated magnetosheath electrons and an injection of magnetosheath ions. Under the observed conditions, reconnected flux tubes created by a transient and localized patch of reconnection located nearer to the subsolar point, will move northward and duskward over Cluster, consistent with observations inside the magnetosphere. The FTE signatures arise from this transient inward motion of reconnection‐associated boundary layers over the spacecraft. We postulate that the transient relocation of C3 into the magnetosheath is due to a region of eroded magnetic flux, lying in the wake of the recoiling FTE, which itself is driven duskward at some fraction of the magnetosheath flow speed. The FTEs pass northward of C3, but the eroded wake, which we term the “traveling magnetopause erosion region” (TMER), is located equatorward of the FTEs and moves duskward over C3.
Reconstruction of two‐dimensional coherent MHD structures in a space plasma: The theory
Authors: Sonnerup Bengt U. Ö. , Teh Wai‐Leong
Published: May 2008

We develop basic theory for the reconstruction of two‐dimensional, time‐stationary, ideal, compressible MHD structures in a space plasma from data taken by a single spacecraft as the structures move past it. The MHD equations are solved as a spatial initial‐value problem in a manner similar to that used in so‐called Grad‐Shafranov (GS) reconstruction (e.g., Sonnerup et al., 2006), the difference being that our new method can deal with general structures, not just those governed by a GS‐like equation. The approach described here represents a first step toward reconstruction of 2D steady state reconnection configurations, viewed in a frame moving with the X‐line: Resistive, electron pressure, and Hall terms are still missing in Ohm's law but resistive and Hall effects can, we argue, ultimately be included. A numerical algorithm to perform the integration has been developed. It is tested by generation of synthetic data from a virtual spacecraft moving through an exact, analytical, axisymmetric solution of the MHD equations; these data are then used for the reconstruction. The exact solution involves isentropic plasma flow at an angle to the magnetic field. In addition to pressure and density, all three magnetic field and flow components are activated in the solution, i.e., they all vary with radius. Results show that the new method works with acceptable accuracy in a rectangular region surrounding the spacecraft path, with the two long sides of the rectangle parallel to the path. As is the case for GS reconstruction, the length of the short sides is limited by spatially growing numerical instability inherent in this type of integration procedure. Applications to actual spacecraft (Cluster) data will be reported separately.
Summer‐winter hemisphere asymmetry of the preliminary reverse impulse of geomagnetic storm sudden commencements at midlatitudes
Authors: Sastri J. H. , Yumoto K. , Rao J. V. S. V. , Ikeda A.
Published: May 2008

We present event‐specific observational evidence for the prevalence of a summer‐winter hemisphere asymmetry of the preliminary reverse impulse (PRI) of geomagnetic storm sudden commencements (SSCs) at midlatitudes of the local afternoon sector. The evidence is culled from the archived 10‐s resolution data of midlatitude stations (geomagnetic latitude 23–46°) of the MM 210 magnetometer network. The hemisphere asymmetry is characterized by a larger peak amplitude of PRI in the summer hemisphere than in the winter hemisphere, and this feature is more prominently seen in the December solstice compared to the June solstice. In the December solstice SSC event, the amplitude of the preliminary reverse impulse, PRI (4.8 nT) at BRV (geomagnetic latitude 36.6°S) in the summer hemisphere is larger by a factor of 6 compared to that at MSR (geomagnetic latitude 37.6°N) in the winter hemisphere. The asymmetry is also apparent at lower latitudes: while the PRI assumed an amplitude of 3.7 nT at LEM (geomagnetic latitude 34.1°S), it is barely discernible at ONW (geomagnetic latitude 31.6°N) in the winter hemisphere. In the June solstice event, the PRI amplitude at RIK (geomagnetic latitude 34.7°N) in the summer hemisphere is higher by a factor of 3.44 compared to that at LEM (geomagnetic latitude 34.1°S) in the winter hemisphere. A similar behavior is also apparent in the equinox event though the hemisphere asymmetry of the preliminary reverse impulse (PRI) here is of moderate strength. In all the SSC events studied, the main impulse (MI) amplitude also exhibited the well‐known summer‐winter asymmetry, but the hemisphere asymmetry is more prominent with the preliminary reverse impulse (PRI) than with the main impulse (MI). Physical processes that could possibly account for the hemisphere asymmetry evidenced of the afternoon PRI at midlatitudes are discussed.