bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design and performance analysis of a novel trellis coded space–time–frequency OFDM transmission scheme
Authors: Oğuz Onur , Aygölü Ümit , Panayırcı Erdal 
Published: April 2007

AbstractIn this paper a new transmit diversity technique is proposed for wireless communications over frequency selective fading channels. The proposed technique utilises orthogonal frequency division multiplexing (OFDM) to transform a frequency selective fading channel into multiple flat fading subchannels on which first space–frequency coding and then additional space–time coding are applied resulting in a space–time–frequency OFDM (STF‐OFDM) scheme. This scheme provides a quasi‐orthogonal 4 × 4 transmission matrix but relax the constraint on channel fading parameters to be constant over four time or frequency slots into two time and two frequency slots. The pairwise error probability of the new scheme is evaluated and new code design criteria are obtained to improve the error performance. 64‐, 128‐ and 256‐state 4‐PSK trellis codes for STF transmission scheme are generated based on these criteria and their frame error performances in an OFDM system are evaluated by computer simulations. Copyright © 2007 John Wiley & Sons, Ltd.
New quasi‐orthogonal BCH‐derived sequences for CDMA applications
Authors: Ricardo Cesaltina N. E. , Ortigueira Manuel D. , Gerald José António B. 
Published: April 2007

AbstractBased on two methods recently proposed—the ‘Ranging Criterion’ (RC) and the ‘Generators Ranging Criterion’ (GRC)—new (quasi‐orthogonal) even BCH‐derived sequences are generated which are very attractive for synchronous or quasi‐synchronous Code Division Multiple‐Access (CDMA) systems. Numerical results show that the new family of BCH‐derived sequences can contain a higher number of quasi‐orthogonal sequences with lower correlation values and higher processing gains (PGs) than the spreading sequences typically used in the third generation of mobile communications system, UMTS or in the recent large area synchronised CDMA (LAS‐CDMA) technology. It is shown that the even BCH‐derived sequences are easily generated by a linear shift register generator, allowing the construction of systems with receiver structures of low complexity as compared with those of quasi‐synchronous systems using low correlation zone sequences, as for instance the LAS‐CDMA system. Copyright © 2007 John Wiley & Sons, Ltd.
Joint channel estimation and equalisation of fast time‐varying frequency‐selective channels
Authors: Gligorevic Snjezana 
Published: April 2007

AbstractThis paper addresses joint channel and data estimation for transmission over frequency‐selective and time‐varying channels based on a Doppler‐variant channel impulse response (CIR). A discrete spreading function (DSF), which corresponds to the Doppler Fourier series of the time‐varying channel taps, is introduced. The spectral leakage associated with the Fourier series representation is reduced by oversampling in Doppler‐direction. This approach, however, requires joint channel estimation and equalisation (JCE). Therefore, a recursive least squares (RLS) algorithm for the DSF estimation is combined with the data detection in a reduced state diagram. Furthermore, an enhanced metric, previously introduced in De Broeck et al. (Proceedings of Second International Workshop on Multi‐Carrier Spread‐Spectrum, 1999; published by Kluwer Academic Publishers: Dordrecht, 2000) for time‐invariant channels, is applied here for path selection. The performance of this metric is investigated here for time‐varying and frequency‐selective (TV‐FS) channels. The performance of the proposed approach is compared with the JCE algorithm which uses RLS estimation of a CIR by simulations. Copyright © 2007 John Wiley & Sons, Ltd.
Random direction or random waypoint? A comparison of mobility models for urban environments
Authors: Kraaier Jan , Killat Ulrich 
Published: April 2007

AbstractThe Random Direction (RD) and the Random Waypoint (RWP) mobility models have been discussed extensively in the literature. The focus of this discussion was the stationary distribution of users and speeds of users. In this paper, we extend the investigation to street‐based variants of the two mobility models. We compare statistical properties including user distribution, sojourn times in hotspots and link durations in ad hoc networks. In order to motivate the use of street‐based mobility models, we also perform a comparison with the basic models. Finally, we present our approach to achieve identical user distributions in both street‐based models and investigate the remaining differences, which prove to be negligible for wireless network simulations. Copyright © 2007 John Wiley & Sons, Ltd.
Expansion of cumulant‐based classifier to frequency shift keying modulations and to the use of support vector machines
Authors: Mustafa H. , Doroslovački M. 
Published: April 2007

AbstractThis paper proposes an expansion of the cumulant‐based classifier of digital modulations to frequency shift keying (FSK) modulations. Cumulant estimates are calculated when the FSK modulation is present. The features obtained from the cumulant estimators are used in a support vector machine (SVM) classifier. The performance of the SVM classifier is compared to other classifiers. Among these other classifiers is the cumulant‐based tree classifier which uses thresholds defined by the asymptotic values of the cumulant estimators. The simulation results show that using SVM classifier improves the performance. Copyright © 2007 John Wiley & Sons, Ltd.
Recurrent disruption of the Iμ splice donor site in t(14;18) positive lymphomas : A potential molecular basis for aberrant downstream class switch recombination
Authors: Ruminy Philippe , Jardin Fabrice , Penther Dominique , Picquenot Jean‐Michel , Parmentier Françoise , Buchonnet Gérard , Bertrand Philippe , Tilly Hervé , Bastard Christian 
Published: April 2007

Abstractt(14;18) positive lymphomas are mature germinal center B‐cell neoplasms. In agreement with this cellular origin, most have somatically mutated immunoglobulin variable genes and the IGH@ locus has almost always been reorganized by class switch recombination (CSR). However, contrasting with normal B‐cells, a majority of cases still express an IgM while the constant genes are normally rearranged only on the non‐productive allele. Concurrently, aberrant intra‐allelic junctions involving downstream switch regions, with a lack of engagement of the switch μ (Sμ), often accumulate on the functional alleles, suggesting some recurrent CSR perturbation during the onset of the disease. To clarify these surprising observations, we addressed the accessibility of the Sμ to the CSR machinery in a large series of patients by characterizing the mutations that are expected to accumulate at this place upon CSR activation. Our data indicate that the Sμ is mutated in a large majority of cases, often on both alleles, indicating that these cells usually reach a differentiation stage where CSR is activated and where this region remains accessible. Interestingly, we also identified a significant cluster of mutations at the splicing donor site of the first exon of the Sμ germline transcripts, on the functional allele. This location suggests a possible relation with CSR perturbations in lymphoma and the clustering points to a probable mechanism of selection. In conclusion, our data suggest that an acquired mutation at the splicing donor site of the Sμ transcripts may participate in the selection of lymphoma cells and play a significant role during the onset of the disease. © 2007 Wiley‐Liss, Inc.
Loss of input from the mossy cells blocks maturation of newly generated granule cells
Authors: Marqués‐Marí Ana‐Isabel , Nacher Juan , Crespo Carlos , Gutièrrez‐Mecinas María , Martínez‐Guijarro Francisco‐José , Blasco‐Ibáñez José‐Miguel 
Published: April 2007

AbstractThe objective of this work is to check whether the input from the mossy cells to the inner molecular layer is necessary for the integration and maturation of the newly generated granule cells of the dentate gyrus (DG) in mice, and if after status epilepticus the sprouting of the mossy fibers can substitute for this projection. Newly generated cells were labeled by administration of 5‐bromo‐deoxyuridine either before or after pilocarpine administration. The neuronal loss in the hippocampus after administration of pilocarpine combined with scopolamine and diazepam seemed restricted to the hilar mossy cells. The maturation of the granule cells was studied using immunohistochemistry for calretinin and NeuN in combination with detection of 5‐bromo‐deoxyuridine. The sprouting of the mossy fibers was detected using Timm staining for zinc‐rich boutons. In normal conditions, granule cells took about 2 weeks to lose the immature marker calretinin. After the loss of the mossy cells, newly generated granule cells remained expressing calretinin for more than a month, until the sprouting of the mossy fibers substituted for the projection of the mossy cells in the inner molecular layer of the DG. Therefore, a proper pattern of connectivity is necessary for the normal development and integration of newly generated granule cells in the adult brain. In a changed environment they cannot adapt transforming in other cell types; simply they are unable to mature. The sprouting of the mossy fibers, although aberrant and a probable source of epileptic activity, may be important for the correct physiology of the granule cells, restoring a likeness of normality in their connective environment. The survival of granule cells incorporated as mature neurons was increased after pilocarpine when compared with normal conditions. Thus, it is likely that the reorganization of the circuitry after the loss of the mossy cells facilitates the survival and incorporation of the newly generated granule cells. © 2007 Wiley‐Liss, Inc.
Rebuilding health systems in post‐conflict countries: estimating the costs of basic services
Authors: Newbrander William , Yoder Richard , Debevoise Anne Bilby 
Published: April 2007

AbstractAfter the fall of the Taliban in 2001, the Afghan transitional government and international donors found the health system near collapse. Afghanistan had some of the worst health indicators ever recorded. To begin activities that would quickly improve the health situation, the Ministry of Health (MOH) needed both a national package of health services and reliable data on the costs of providing those services. This study details the process of determining national health priorities, creating a basic package of services, and estimating per capita and unit costs for providing those services, with an emphasis on the costing exercise. Strategies for obtaining a rapid yet reasonably accurate estimate of health service costs nationwide are discussed. In 2002 this costing exercise indicated that the basic package of services could be provided for US$4.55 per person. In 2006, the findings were validated: the four major donors who contracted with non‐governmental organizations (NGOs) to provide basic health services for nearly 80% of the population found per capita costs ranging from $4.30 to $5.12. This study is relevant for other post‐conflict countries that are re‐establishing health services and seeking to develop cost‐effective and equitable health systems. Copyright © 2007 John Wiley & Sons, Ltd.
DNA damage response involves modulation of Ku70 and Rb functions by cyclin A1 in leukemia cells
Authors: Ji Ping , Bäumer Nicole , Yin Taijun , Diederichs Sven , Zhang Feng , Beger Carmela , Welte Karl , Fulda Simone , Berdel Wolfgang E. , Serve Hubert , Müller‐Tidow Carsten 
Published: April 2007

AbstractCyclin A1 plays a critical role in hematopoietic malignancies, notably, acute myeloid leukemia. The molecular mechanisms of cyclin A1 action are incompletely understood. Here, we show that cyclin A1 functions are mediated by the retinoblastoma and the Ku70 pathway. High levels of cyclin A1 and the associated CDK2 kinase activity were associated with increasing levels of phosphorylated retinoblastoma in vivo. UV irradiation induced a switch of the CDK2 towards cyclin A1, with accordance to changes in CDK2 kinase activity. The C‐terminus of cyclin A1 directly interacted with Ku70, and DNA binding activity of Ku70 was modulated by cyclin A1/CDK2 and phosphatase treatment. Cyclin A1‐deficiency induced by shRNA increased apoptosis that is induced by DNA damage and death receptor ligands. Taken together, these analyses demonstrate that cyclin A1 exerts antiapoptotic functions by interacting with retinoblastoma and Ku proteins in leukemia cells. © 2007 Wiley‐Liss, Inc.
Salad vegetables dietary pattern protects against HER‐2‐positive breast cancer: A prospective Italian study
Authors: Sant Milena , Allemani Claudia , Sieri Sabina , Krogh Vittorio , Menard Sylvie , Tagliabue Elda , Nardini Elena , Micheli Andrea , Crosignani Paolo , Muti Paola , Berrino Franco 
Published: April 2007

AbstractStudies investigating the relation of diet to breast cancer have produced conflicting results. We hypothesized that dietary factors associated with breast cancer risk might differentially influence the HER‐2 status of the cancers that develop, and investigated this hypothesis by analyzing the data of the ORDET prospective study. We analyzed 8,861 volunteer women residents of the Varese Province, Italy, for whom we had full data. By December 31, 2001, 238 cases had occurred in which HER‐2 status was known. Four dietary patterns had been identified previously by factor analysis: salad vegetables (high consumption of raw vegetables and olive oil), prudent (cooked vegetables, poultry, fish), western (potatoes, meat, eggs, butter), and canteen (pasta, tomato sauce, wine). In our study, relative risks (RRs) of developing HER‐2‐positive and HER‐2‐negative breast cancers by tertiles of dietary pattern factor scores were assessed by multinomial logistic regression. The salad vegetables dietary pattern had a protective effect against HER‐2‐positive cancers (RR = 0.25, 95% CI 0.10–0.64, for the highest tertile; ptrend = 0.001), much stronger than for HER‐2‐negative cancers (pheterogeneity = 0.039). This important finding that a salad vegetables dietary pattern protects mainly against a specific breast cancer subtype indicates that future studies on environmental/dietary risk factors should explicitly take account of the heterogeneity of breast cancer phenotypes. © 2007 Wiley‐Liss, Inc.
Dietary patterns, the Alternate Healthy Eating Index and plasma sex hormone concentrations in postmenopausal women
Authors: Fung Teresa T. , Hu Frank B. , Barbieri Robert L. , Willett Walter C. , Hankinson Susan E. 
Published: April 2007

AbstractTo evaluate the association between overall diet and sex hormones concentrations, we collected blood from 578 postmenopausal women ages 43 and 69 years in 1989 or 1990. Food intake was measured in 1990 via a food frequency questionnaire. We calculated the Alternate Healthy Eating Index (AHEI), and dietary patterns were identified by factor analysis. The cross‐sectional association between diet and estrogens, sex hormone binding globulin (SHBG) were evaluated with linear regression and adjusted for energy and other potential confounders. We found a higher AHEI score was associated with lower concentrations of estradiol, free estradiol, and higher concentrations of SHBG. The prudent pattern, with higher intakes of fruits, vegetables, and whole grains, was not associated with any sex hormones. The Western pattern, which represents higher intakes of red and processed meats, refined grains, sweets and desserts, was associated with a higher level of estradiol and lower concentrations of SHBG. Further adjustment for BMI attenuated these results except for free estradiol (5th vs. 1st quintile = 0.09 vs. 0.11 pg/mL, p for trend = 0.03). In addition, the AHEI was inversely associated with estradiol among those with BMI > 25, and Western pattern with SHBG among those with BMI < 25. In conclusion, we observed inverse associations between the AHEI score and several estrogens, and it was positively associated with plasma levels of SHBG. In contrast, the Western pattern was positively associated with estrogen levels and inversely with SHBG. However, these associations appeared to be largely accounted for by BMI. © 2007 Wiley‐Liss, Inc.
Global expression profiling of murine MEN1‐associated tumors reveals a regulatory role for menin in transcription, cell cycle and chromatin remodelling
Authors: Mould Arne W. , Duncan Russell , Serewko‐Auret Magdalena , Loffler Kelly A. , Biondi Christine , Gartside Michael , Kay Graham F. , Hayward Nicholas K. 
Published: April 2007

AbstractAlthough the identification of menin‐interacting partners and other evidence support a role for menin, the multiple endocrine neoplasia type 1 gene (MEN1) product, in regulating gene expression, little is known about the cellular pathways dysregulated by menin loss during tumorigenesis. The mouse models of MEN1 accurately mimic the human syndrome and provide an opportunity to assess the transcriptional effects of Men1 deletion in different endocrine tumor types to identify common pathway aberrations underlying tumorigenesis in MEN1‐affected tissues. We compared the global gene expression profiles of pituitary adenomas and pancreatic islet tumors with control tissues from wild‐type littermates. Amongst the 551 differentially expressed genes was significant over‐representation of genes associated with chromatin remodelling, transcription and cell cycling, including some genes known to encode menin‐binding partners, e.g., Rhox5 and Mll1. Consistent with increased cell‐cycle transition from G1 to S phase was an elevation of Cdc7 expression in the tumors, which was confirmed by qRT‐PCR using independent samples. In support of previous findings in islet tumors, we found down‐regulation of the cell‐cycle regulator, p18, in both the pancreatic islet and pituitary adenomas, suggesting that reduced p18 levels may be important for Men1‐related tumorigenesis in multiple tissues. Surprisingly, we identified increased p16 transcript in pancreatic islet and pituitary tumors. This was accompanied by increased cytoplasmic localization p16 protein in tumor cells. The specific genes and general pathways we have found to be commonly dysregulated in MEN1 tumors, provide a platform for determining their roles in endocrine tumorigenesis. © 2007 Wiley‐Liss, Inc.
Co‐twin control and cohort analyses of body mass index and height in relation to breast, prostate, ovarian, corpus uteri, colon and rectal cancer among Swedish and Finnish twins
Authors: Lundqvist Ellen , Kaprio Jaakko , Verkasalo Pia K. , Pukkala Eero , Koskenvuo Markku , Söderberg Karin C. , Feychting Maria 
Published: April 2007

AbstractAssociations between anthropometric measures and cancer have been studied previously, but relatively few studies have had the opportunity to control for genetic and early shared environmental factors. In this study, we analyzed 2 twin cohorts from Sweden born 1886–1925 (n = 21,870) and 1926–1958 (n = 30,279) and 1 from Finland born 1880–1958 (n = 25,882) including in total 78,031 twins, and studied the association between BMI and height and risk of prostate, breast, ovarian, corpus uteri, colon and rectal cancer. The cohorts were both analyzed through a co‐twin control method and as traditional cohorts. In co‐twin control analyses, older obese (BMI ≥ 30 kg/m2) subjects (median age 56 years at baseline) were at higher risk of cancer of the corpus uteri (OR = 3.0; 95% CI 0.9–10.6), colon (OR = 1.9; 95% CI 0.8–4.5) and breast (OR = 2.5; 95% CI 1.3–4.2). For younger obese women (median age 30 years at baseline), an inverse tendency was observed for breast cancer (OR = 0.6; 95% CI 0.3–1.5, p for trend = 0.05). The tallest women had an increased risk of breast (OR = 1.8; 95% CI 1.3–2.7) and ovarian cancer (OR = 1.7; 95% CI 0.8–3.5). No consistent associations were found for prostate cancer either for BMI or height. There are some suggestions in our study that uncontrolled genetic or early shared environmental factors may affect risk estimates in studies of anthropometric measures and cancer risk, but do not explain observations of increased cancer risks related to BMI or height. © 2007 Wiley‐Liss, Inc.
Biocompatibility evaluation of crosslinked chitosan hydrogels after subcutaneous and intraperitoneal implantation in the rat
Authors: Azab Abdel Kareem , Doviner Victoria , Orkin Boris , Kleinstern Jackie , Srebnik Morris , Nissan Aviram , Rubinstein Abraham 
Published: April 2007

AbstractThe aim of the present study was to evaluate the toxicity of biodegradable hydrogels in the rat with a future aim of utilizing this hydrogel as a vehicle for brachytherapy delivery in cancer patients. Two types of chitosan hydrogels: fast degrading and slow degrading; were prepared and surgically implanted in rats. The adjacent tissue response to the gels after subcutaneous and intraperitoneal implantation was examined histologically and found to be identical to typical foreign body response and was milder than the response to absorbable surgical sutures (Vicril®). Neither tissue damage nor gel fragments could be detected in distant organs (brain, heart, lungs, liver, spleen, kidney, and sternal bone marrow) after implantation of the hydrogels. The degradation mechanism of the gels was studied invivo, and it was deduced that an oxidative process degraded the chitosan. Loading the hydrogels with a radioisotope (131I‐norcholesterol) caused a severe tissue response and necrosis in adjacent tissues only at a distance of several microns. It is concluded that crosslinked chitosan implants could serve as alternative, biocompatible, and safe biodegradable devices for radioisotope delivery in brachytherapy for cancer. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2007.
Regulation of endothelial cell function by GRGDSP peptide grafted on interpenetrating polymers
Authors: Patel Shyam , Tsang Jonathan , Harbers Gregory M. , Healy Kevin E. , Li Song 
Published: April 2007

AbstractVascular endothelium plays an important role in preventing thrombogenesis. Bioactive molecules such as fibronectin‐derived peptide Gly‐Arg‐Gly‐Asp‐Ser‐Pro (GRGDSP) can be used to modify the surface of cardiovascular implants such as vascular grafts to promote endothelialization. Here we conjugated GRGDSP peptide to the nonfouling surface of an interpenetrating polymer network (IPN), and investigated the effects of the immobilized GRGDSP molecules on EC functions under static and flow conditions at well‐defined GRGDSP surface densities (∼0 to 3 pmol/cm2). EC adhesion and spreading increased with GRGDSP surface density, reached a plateau at 1.5 pmol/cm2, and increased further beyond 2.8 pmol/cm2. Cell adhesion and spreading on GRGDSP induced two waves of extracellular signal‐regulated kinase (ERK) activation, and 0.2 pmol/cm2 density of GRGDSP was sufficient to activate ERK. EC proliferation rate was not sensitive to GRGDSP surface density, suggesting that cell spreading at low‐density of GRGDSP is sufficient to maintain EC proliferation. EC migration on lower‐density GRGDSP‐IPN surfaces was faster under static condition. With the increase of GRGDSP density, the speed and persistence of EC migration dropped quickly (0.2–0.8 pmol/cm2) and reached a plateau, followed by a slower and gradual decrease (1.5–3.0 pmol/cm2). These data suggest that the changes of EC functions were more sensitive to the increase of GRGDSP density at lower range. Under flow condition with shear stress at 12 dyn/cm2, EC migration was inhibited on GRGDSP‐IPN surfaces, which may be attributed to the assembly of large focal adhesions induced by shear stress, suggesting a catch‐bond characteristic for RGD‐integrin binding. This study provides a rational base for surface engineering of cardiovascular implants. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2007.