bluuebunny/crossref_metadata_2025_split huggingface dataset:
Alewife planktivory controls the abundance of two invasive predatory cladocerans in Lake Michigan
Authors: POTHOVEN STEVEN A. , VANDERPLOEG HENRY A. , CAVALETTO JOANN F. , KRUEGER DAMON M. , MASON DORAN M. , BRANDT STEPHEN B. 
Published: February 2007

Summary1. We sampled along a nearshore transect (10‐m bathymetric contour) in Lake Michigan to determine diet, 24‐h feeding periodicity, daily ration and food requirements of an invasive fish, the alewife, Alosa pseudoharengus, relative to zooplankton abundance and production. Our objective was to determine whether the alewife controls the abundance of two invasive, predatory cladocerans, Bythotrephes longimanus and Cercopagis pengoi.2. Bosminidae was the most abundant prey taxon and Chydoridae, Leptodora, Chironomidae and Bythotrephes were the least abundant. Neither Bythotrephes nor Cercopagis were important prey for small alewives (≤100 mm). Bythotrephes was eaten by over 50% of large alewives (>100 mm) and accounted for 10–27% of the diet weight. Cercopagis was eaten by about 30% of the large alewives but only accounted 1% of the diet weight.3. Food weight in stomachs was highest early in the night for small alewives and lowest at night for large alewives. Chironomidae and large Chydoridae were the preferred prey of small alewives. Bythotrephes and large Chydoridae were the preferred prey for large alewives.4. Food requirements of alewife were much less than production for most prey taxa, although the consumption of Bythotrephes greatly exceeded production on both dates. Alewives consumed only 3% of Cercopagis production. High selectivity and food requirements of alewife for Bythotrephes, and low selectivity and food requirements for Cercopagis, probably explain the difference in abundance between these two invasive cladocerans at our nearshore site in Lake Michigan.
Fourier reconstruction with sparse inversion
Authors: Zwartjes P. , Gisolf A. 
Published: February 2007

ABSTRACTThe problem of seismic data reconstruction is posed as an inverse problem where the objective is to obtain the Fourier coefficients that synthesize the signal. Once the coefficients have been found, they are used to reconstruct the data on a uniformly spaced grid. A non‐quadratic model weight function is included to stabilize the inversion and to provide the additional information required to interpolate through gaps. In the reconstruction of a non‐uniformly sampled trace, an image and a marine 3D VSP shot‐record, the method shows improved reconstruction in large gaps and is less sensitive to the spatial bandwidth used in the inversion compared to Fourier reconstruction without the non‐quadratic model weight function.
Non‐minimum phase wavelet estimation by non‐linear optimization of all‐pass operators
Authors: Misra Somanath , Sacchi Mauricio D. 
Published: February 2007

ABSTRACTConvolution of a minimum‐phase wavelet with an all‐pass wavelet provides a means of varying the phase of the minimum‐phase wavelet without affecting its amplitude spectrum. This observation leads to a parametrization of a mixed‐phase wavelet being obtained in terms of a minimum‐phase wavelet and an all‐pass operator. The Wiener–Levinson algorithm allows the minimum‐phase wavelet to be estimated from the data. It is known that the fourth‐order cumulant preserves the phase information of the wavelet, provided that the underlying reflectivity sequence is a non‐Gaussian, independent and identically distributed process. This property is used to estimate the all‐pass operator from the data that have been whitened by the deconvolution of the estimated minimum‐phase wavelet. Wavelet estimation based on a cumulant‐matching technique is dependent on the bandwidth‐to‐central‐frequency ratio of the data. For the cumulants to be sensitive to the phase signatures, it is imperative that the ratio of bandwidth to central frequency is at least greater than one, and preferably close to two. Pre‐whitening of the data with the estimated minimum‐phase wavelet helps to increase the bandwidth, resulting in a more favourable bandwidth‐to‐central‐frequency ratio. The proposed technique makes use of this property to estimate the all‐pass wavelet from the prewhitened data. The paper also compares the results obtained from both prewhitened and non‐whitened data. The results show that the use of prewhitened data leads to a significant improvement in the estimation of the mixed‐phase wavelet when the data are severely band‐limited. The proposed algorithm was further tested on real data, followed by a test involving the introduction of a 90°‐phase‐rotated wavelet and then recovery of the wavelet. The test was successful.
Estimation of clay content in soil based on resistivity modelling and laboratory measurements
Authors: Shevnin Vladimir , Mousatov Aleksandr , Ryjov Albert , Delgado‐Rodriquez Omar 
Published: February 2007

ABSTRACTThe determination of clay content in near‐surface formations is crucial for geotechnical, hydrogeological and oil‐contamination studies. We have developed a technique for estimating clay content that consists of the minimization of the difference between the theoretically calculated and measured soil resistivities as a function of water salinity. To calculate the resistivity, we used a model that takes into account the electrochemical processes in the clay micropores. The experimental measurements of soil resistivity were performed on soil samples, completely saturated by brines at different concentrations of NaCl salt in the range 0.6–100 g/l, to obtain the resistivity versus salinity curve. The parameters obtained with this curve inversion are the clay content, the total porosity and the cation exchange capacity. To verify the new technique, we determined clay concentrations of artificial mixtures of calibrated sand and clay. The relative mean error in the clay content does not exceed 20% for a 5% fitting error of the resistivity versus salinity curves. Such evaluations allow the correct separation of the main lithological groups (sand, sandy loam, loam, and light, medium and heavy clay).We applied this technique to estimate the petrophysical parameters of soils (clay content, porosity and cation exchange capacity) at various sites in Mexico. The results improved the interpretation of the vertical electrical soundings, the lithological soil characterization and the delineation of oil‐contaminated areas.
Quantitative detection of fluid distribution using time‐lapse seismic
Authors: Tsuneyama Futoshi , Mavko Gary 
Published: February 2007

ABSTRACTAlthough previous seismic monitoring studies have revealed several relationships between seismic responses and changes in reservoir rock properties, the quantitative evaluation of time‐lapse seismic data remains a challenge. In most cases of time‐lapse seismic analysis, fluid and/or pressure changes are detected qualitatively by changes in amplitude strength, traveltime and/or Poisson's ratio.We present the steps for time‐lapse seismic analysis, considering the pressure effect and the saturation scale of fluids. We then demonstrate a deterministic workflow for computing the fluid saturation in a reservoir in order to evaluate time‐lapse seismic data. In this approach, we derive the physical properties of the water‐saturated sandstone reservoir, based on the following inputs: VP, VS, ρ and the shale volume from seismic analysis, the average properties of sand grains, and formation‐water properties. Next, by comparing the in‐situ fluid‐saturated properties with the 100% formation‐water‐saturated reservoir properties, we determine the bulk modulus and density of the in‐situ fluid. Solving three simultaneous equations (relating the saturations of water, oil and gas in terms of the bulk modulus, density and the total saturation), we compute the saturation of each fluid. We use a real time‐lapse seismic data set from an oilfield in the North Sea for a case study.
Single nucleotide polymorphisms in succinate dehydrogenase subunits and citrate synthase genes: association results for impaired spermatogenesis
Authors: Bonache Sandra , Martínez Juanjo , Fernández Marlin , Bassas Lluís , Larriba Sara 
Published: February 2007

AbstractEvaluation of the possible implication of the SDHA, SDHB, SDHC, SDHD and CS genes in non‐obstructive male infertility was performed on the basis that sperm concentration in the ejaculate has been previously correlated with nuclear‐encoded mitochondrial enzyme activities (the four subunits of succinate dehydrogenase/complex II of the respiratory chain and citrate synthase). We performed an exhaustive analysis of the five genes for the presence of sequence variants that could be associated with impairment of sperm production. blastn searches in the genomic sequence NCBI database evidenced the presence of highly homologous sequences elsewhere on the genome that can interfere with polymerase chain reaction experiments. Therefore, a careful design of the analytical strategy to search for sequence variants was performed. In this report, we provide primer sequences that allowed selective amplification of coding and immediate flanking regions of the five genes. Fifty‐five sequence variations in the five genes were identified in infertile and normozoospermic fertile individuals as controls and only one of them (SDHA c.456+32G>A) showed significant genotype association with impairment of sperm production. Moreover, new single nucleotide polymorphisms identified should be useful in future association studies for other human diseases related to nuclear‐encoded genes, leading to mitochondrial respiratory chain activity impairment revealing the physiological role of these genes.
Measuring gonadotropins is of limited value in detecting hypogonadism in ageing men: the Tromsø study
Authors: Svartberg Johan , Jorde Rolf 
Published: February 2007

SummaryTestosterone levels decrease with age. The mechanisms responsible for the age‐related decrease in testosterone concentration are still being debated, and probably involve all three levels of the hypothalamo‐pituitary‐testicular axis. Luteinizing hormone (LH) concentration is often measured in combination with testosterone, but its value is questionable when considering the testosterone levels of older men. The objective of the present study was to examine the associations of endogenous gonadotropin and testosterone levels both in a cross‐sectional cohort of 3447 men participating in the fifth Tromsø study and longitudinally in a cohort of 1352 men participating in both the fourth and the fifth Tromsø study. Total testosterone, LH, follicle‐stimulating hormone and sex hormone‐binding globulin levels were measured with immunoassay while free testosterone levels were calculated. Total testosterone and LH were independently and positively associated in the cross‐sectional analyses (p < 0.001). In the longitudinal study, however, LH levels did not predict changes in total and free testosterone levels. Thus, in clinical practice, measuring gonadotropins seems to be of limited value in detecting hypogonadism in ageing men.
Prostatic massage: a simple method of semen retrieval in men with spinal cord injury
Authors: Arafa Mohamed Mostafa , Zohdy Wael Ahmed , Shamloul Rany 
Published: February 2007

SummaryThe aim of this study was to evaluate the efficacy of prostatic massage (PM) as a method for obtaining semen in men with spinal cord injury (SCI) and to evaluate the semen parameters in the semen samples obtained by this method. Sixty‐nine patients with SCI underwent PM as a trial for semen retrieval. History taking, examination and hormonal assay analysis (follicle‐stimulating hormone, luteinizing hormone, prolactin and testosterone) were performed in all patients. Patients were grouped as follows: group ‘A’ where sperm could be successfully retrieved by PM and group ‘B’ where no sperm could be retrieved. PM resulted in the production of prostatic secretion in 51 patients (73.9%) and no secretion was obtained in 18 patients. Spermatozoa were successfully retrieved in only 22 patients (31.9%). The semen analysis of the sperm‐positive samples showed asthenoteratozoospermia with decreased vitality and increased number of leucocytes. Semen collection by PM was significantly higher in patients with an SCI level above T10. PM is a safe and simple outpatient clinic procedure that can be easily used to retrieve semen in men with SCI.
Assessment of nuclear DNA integrity of epididymal spermatozoa following experimental chronic spinal cord injury in the rat
Authors: Talebi Ali Reza , Khalili Mohammad Ali , Hossaini Ahmad 
Published: February 2007

SummaryInfertility is considered as one of the major problems associated with spinal cord injury (SCI). However, the exact underlying mechanism is still unknown. Therefore, the main objective of this experimental study was to evaluate the effect of chronic SCI on sperm parameters as well as chromatin integrity and DNA of spermatozoa aspirated from cauda epididymis of rats. Forty‐five adult Wistar rats were divided into three groups – SCI, sham, and control. Following laminectomy, SCI was induced onto exposed dura matter (T10). The sham group underwent laminectomy of T10 only, while the control rats were not exposed to any type of injury or medication. The cauda epididymal sperms were aspirated after 8 weeks for analysis of sperm parameters and sperm chromatin integrity with aniline blue (AB), chromomycin A3 (CMA3), sodium dodecyl sulphate (SDS), and acridine orange (AO) tests. The sperm progressive motility and normal morphology of SCI rats were significantly changed when compared with other groups (p < 0.05). In addition, AB as well as CMA3 tests were insignificantly increased in the SCI group when compared with the sham and control groups. However, SDS and AO tests were significantly changed in SCI samples when compared with the sham and control groups (p < 0.001). The results showed that chronic SCI in rat disturbs sperm parameters as well as nuclear maturity and DNA integrity of sperms. Therefore, sperm chromatin structure is compromised in SCI animals as revealed by chromatin structural probes. These alterations may reduce the fertility potential of the male gamete following SCI.
The mouse as a model for the study of penile erection: moving towards a smaller animal
Authors: Piao Shuguang , Ryu Ji‐Kan , Shin Hwa‐Yean , Han Jee‐Young , Lee Hong‐Sik , Suh Jun‐Kyu 
Published: February 2007

SummaryWe evaluated erectile haemodynamics in mice and characterized the corpus cavernosum morphologically. Four‐month‐old male BALB/c mice and Sprague–Dawley rats were used. The following stimulation parameters were tested to achieve maximal erectile responses: voltage, 1–6 V; frequency, 6–24 Hz; pulse width, 1 msec; duration, 1 min (n = 7 per group). In a separate group of mice and rats (n = 10 per group), we measured systemic arterial pressure by use of either a 24‐gauge angiocatheter or smaller calibre PE‐10 tubing. Cavernous tissues from mice, rats or patients with psychogenic erectile dysfunction were stained for factor VIII, α‐actin and Masson trichrome. Electrical stimulation of the cavernous nerve in mice produced voltage‐dependent erectile responses of up to 5 V, with the highest response at a frequency of 12 Hz. The maximal intracavernous pressure recorded at this stimulation parameter was comparable with that in rats. A PE‐10 catheter was more reliable for measuring systemic arterial pressure in mice than was a 24‐gauge angiocatheter, and the values recorded were similar between mice and rats. The content of endothelial cells, smooth muscle cells and collagen was similar between mice and rats. However, the cavernous tissue of both animals contained lesser amounts of smooth muscle cells and greater amounts of collagen than that of humans (p < 0.01). These results suggest that the mouse is a useful and technically feasible model for the study of penile erection and has functional and structural properties similar to those of rats.
Comprehensive analysis of gene expression in testes producing haploid germ cells using DNA microarray analysis
Authors: Ike Akiko , Tokuhiro Keizo , Hirose Mika , Nozaki Masami , Nishimune Yoshitake , Tanaka Hiromitsu 
Published: February 2007

SummaryThe comprehensive changes in testicular gene expression before and after haploid germ cell differentiation were examined using microarray analysis. Approximately 14 000 expressed sequence tag (EST) clones of Mouse FANTOM Array ver.1 were hybridized with probes generated from mRNA of adult and juvenile (17 days postpartum) testes before the onset of spermiogenesis. Of 1315 genes that exhibited reproducible changes in expression (p < 0.05), 46% exhibited an increase of twofold or more in adults compared to juveniles, and 22% a decrease of twofold or more. The analysis not only confirmed the reported haploid‐specific expression of several known genes, but also provided new information on the differential expression of various other genes, including upregulated genes such as Allc and Skd3 and downregulated genes such as hbb b1, before or after the onset of spermiogenesis. Based on the fundamental difference in expression profiles, and molecular functions of the encoded products, the genes were classified into several groups: postmeiotically upregulated genes encoding various enzymes, structural and regulatory proteins, and chaperones, and downregulated genes encoding haemoglobins and oxidation/reduction‐related proteins or the machinery associated with protein synthesis, such as ribosomal proteins.
The equilibrium of XIAP and Smac/DIABLO expression is gradually deranged during the development and progression of testicular germ cell tumours
Authors: Kempkensteffen Carsten , Jäger Tobias , Bub Johannes , Weikert Steffen , Hinz Stefan , Christoph Frank , Krause Hans , Schostak Martin , Miller Kurt , Schrader Mark 
Published: February 2007

SummaryOverexpression of the inhibitor of apoptosis protein (IAP) XIAP (BIRC4) and downregulation of its antagonist Smac/DIABLO (DIABLO) are associated with the onset and progression of various malignancies. In this study, real‐time RT‐PCR was used to quantify the mRNA expression of XIAP and Smac/DIABLO in normal testicular tissue (n = 19), testicular carcinoma in situ (CIS; n = 4), testicular seminomas (n = 64) and non‐seminomatous germ cell tumours (NSGCT; n = 35). XIAP and Smac/DIABLO were commonly expressed in normal and malignant testicular tissue with no apparent differences in XIAP mRNA levels among the histologic subgroups. Smac/DIABLO levels, on the other hand, gradually decreased from normal testicular tissue to CIS and seminomas and finally to NSGCT (p < 0.001). An inverse trend was observed when calculating the XIAP‐to‐Smac/DIABLO ratio (p < 0.001). This ratio differed when comparing normal testicular tissue with CIS (p = 0.014), seminomas (p < 0.001) and NSGCT (p < 0.001) and when comparing seminomas with NSGCT (p = 0.002), whereas no such difference was observed between CIS and seminomas (p = 0.302). TGCT patients dichotomized by the overall median XIAP‐to‐Smac/DIABLO ratio were more likely to present with a high ratio in clinical stage (CS) III than in CS I or II (p = 0.034). These data indicate that the balance of mRNA expression between XIAP and Smac/DIABLO is altered in favour of antiapoptotic XIAP during the development and progression of TGCT. Thus the expression of proapoptotic Smac/DIABLO is lowest in NSGCT and stage III tumours.
c‐Myc partially mediates IFNγ‐induced apoptosis in the primary hepatocyte
Authors: McCullough C. T. , Tura B. J. , Harrison D. J. 
Published: February 2007

SummaryInterferon‐gamma (IFNγ) is a central component of the complex cytokine and inflammatory response that contributes to liver cell injury in hepatitis. We report that in the primary hepatocyte IFNγ synergizes with the mechanistically distinct apoptotic stimuli CD95, tumour necrosis factor‐alpha (TNFα) and UV‐irradiation. For the first time in primary hepatocytes, we show that IFNγ‐mediated apoptotic signalling requires the cell surface interaction of CD95 and its ligand, and we demonstrate that IFNγ induces soluble CD95 ligand release from hepatocyte monolayers. Utilizing c‐myc phosphorothioate antisense fragments, we suppresses hepatocyte apoptosis induced by IFNγ. In summary, we identify apoptotic pathways that contribute to IFNγ‐mediated cell death. The hepatocellular response to IFNγ signalling can be modulated by cytokines and by the interruption of CD95 interaction with its ligand. We present evidence to suggest that c‐myc contributes to IFNγ signalling.
How two different host species influence the performance of a gregarious parasitoid: host size is not equal to host quality
Authors: HÄCKERMANN JOHANNA , ROTT ANJA S. , DORN SILVIA 
Published: February 2007

Summary

Hyssopus pallidus Askew (Hymenoptera, Eulophidae) is a gregarious ectoparasitoid of the two tortricid moths species Cydia molesta Busck and C. pomonella L. (Lepidoptera, Tortricidae). It paralyses and parasitizes different larval instars of both species inside the apple fruit, which leads to the death of the caterpillar.
We assessed the influence of host species characteristics and host food on the performance of the parasitoid female in terms of clutch size decisions and fitness of the F1 generation.
A comparison of clutch size revealed that female parasitoids deposited similar numbers of eggs on the comparatively smaller C. molesta hosts as on the larger C. pomonella hosts. The number of parasitoid offspring produced per weight unit of host larva was significantly higher in C. molesta than in C. pomonella, which is contrary to the general prediction that smaller hosts yield less parasitoid offspring. However, the sex ratio was not influenced by host species that differed considerably in size.
Despite the fact that less host resources were available per parasitoid larva feeding on C. molesta caterpillars, the mean weight of emerging female wasps was higher in the parasitoids reared on C. molesta. Furthermore, longevity of these female wasps was neither influenced by host species nor by the food their host had consumed. In addition we did not find a positive relationship between adult female weight and longevity.
Parasitoid females proved to be able to assess accurately the nutritional quality of an encountered host and adjust clutch size accordingly. These findings indicate that host size is not equal to host quality. Thus host size is not the only parameter to explain the nutritional quality of a given host and to predict fitness gain in the subsequent generation.