bluuebunny/crossref_metadata_2025_split huggingface dataset:
From cell capacity to subcarrier allocation in OFDMA
Authors: Pfletschinger Stephan , Ibars Christian 
Published: March 2006

AbstractIn this paper, we show how a fundamental result from information theory can be used to calculate the aggregate channel capacity in the uplink of an access point. The fundamental limits for this cell capacity provide an upper bound for any practically implementable multiple‐access scheme. Based on the famous iterative water‐filling algorithm, we derive an adaptive method for maximising the sum rate in the uplink of a multi‐user OFDM system. This approach results in a surprisingly simple algorithm for the subcarrier allocation in OFDMA. We also evaluate the possible gains that can be obtained by sharing a subcarrier by multiple users and compare its performance to the theoretical limit as well as to a low‐complexity solution. Finally, we show how these methods can be implemented using coded QAM with iterative decoding and we outline how they can be combined with a scheduling strategy. Copyright © 2006 AEIT.
On the outage behaviour of large DS‐CDMA systems with LMMSE detection
Authors: Prätor Oliver , Fettweis Gerhard P. 
Published: March 2006

AbstractThe outage behaviour of the single cell DS‐CDMA uplink is investigated for flat Rayleigh fading channels. Goal of the work is to find an analytical way for the optimisation of the system spectral efficiency under some outage probability constraint by adjusting parameters such as modulation, spreading factor, code rate and number of codes per user. Therefore, the results of the asymptotic analysis for large CDMA systems with random spreading codes are used to obtain the signal‐to‐interference‐and‐noise ratio after the linear minimum mean‐squared‐error detector. This information is then deployed to characterise the system performance using bounds of the information theory. First, the ergodic behaviour is investigated with respect to the spectral efficiency for both coding at capacity and discrete modulation and coding at cut‐off rate. Then, the outage probability is defined and studied for coding at capacity. The influence of the system load on the outage is determined analytically and compared to simulation results. Afterwards, the impact of modulation and coding at cut‐off rate on the outage behaviour is considered. An expression is presented that allows to easily determine the additional required signal‐to‐noise ratio for modulation and coding at cut‐off rate from the capacity results. Finally, the investigations are extended to determine the maximum system spectral efficiency under given outage constraints. The optimum system loads corresponding to the maximum efficiencies are presented and shown to vary for the different modulation schemes. Copyright © 2006 AEIT.
Orthogonal transmit beamforming scheme based on semidefinite optimisation
Authors: Xu Hongji , Liu Ju , Rubio Francisco , Perez‐Neira Ana I. 
Published: March 2006

AbstractThe multiple‐access interference (MAI) is one of the major factors threatening the performance of multi‐user systems. Transmit beamforming is a powerful strategy to increase the system capacity and mitigate interference. Traditional zero‐forcing transmit beamforming (ZFTBF) is an effective means to remarkably suppress MAI if the downlink channel is precisely known. However, it is very difficult to get exact information on the actual channel in realistic scenarios. In this paper, we present an approach to achieve orthogonal transmit beamforming (OTBF), only in virtue of statistical information of the downlink channel by using semidefinite optimisation tools. Different criteria are considered to solve the same problem by satisfying specific constraints between the total transmission power and the quality of service (QoS) requirements of individual users. Furthermore, robust designs for the presented strategies are also analysed. Simulation results show the effectiveness and the robustness of these strategies. Copyright © 2006 AEIT.
Bit‐interleaved coded irregular modulation
Authors: Schreckenbach F. , Bauch G. 
Published: March 2006

AbstractWe consider a simple method to improve the adaptiveness and flexibility of bit‐interleaved coded modulation (BICM) with different iterative decoding schemes for bandwidth efficient transmission. The basic idea is to apply different signal constellations and mappings within one code word. The combination of different signal constellations allows a fine adaptation of the data rate to the channel characteristics with the modulation, even if only the average channel state is known at the transmitter. For a receiver performing iterative demapping and decoding (so called BICM‐ID system), the mixture of different mappings enables an optimisation of the iterative decoding process according to the system requirements. We call this approach bit‐interleaved codedirregularmodulation (BICIM) and analyse it using EXIT charts, capacity, error bounds and error rate simulations. Copyright © 2006 AEIT.
A 900 MHz CMOS RF transceiver including digital baseband and hardware‐MAC for IEEE 802.15.4/ZigBeeTM applications
Authors: Göpfert Lars , Hofmann Falk , Jacobasch Guido 
Published: March 2006

AbstractThis paper presents a fully‐integrated RF transceiver operating from 860 to 930 MHz. The device parameters are compliant to the IEEE 802.15.4 standard. The analogue portion of the chip contains a direct‐conversion receiver, a fractional‐N PLL, a direct‐conversion transmitter and a TR‐switch. Digital baseband signal processing as well as MAC support are also implemented on the same chip. Only minimal external components are needed to form a complete wireless network application two low‐cost crystals, the PLL loop filter, an antenna and a low‐cost 8 bit microcontroller. Therefore, this chip is one of the most integrated 802.15.4 transceiver ICs presented to date. The receiver input sensitivity is −98 dBm. The chip is fabricated in a 0.25 μm CMOS technology with MIM‐capacitors, deep n‐well and a thick top metal layer. Copyright © 2005 AEIT.
Synthesis and Characterization of Pt/C Nanocatalysts Using Room Temperature Ionic Liquids for Fuel Cell Applications
Authors: Xue X. , Liu C. , Lu T. , Xing W. 
Published: March 2006

AbstractCarbon supported Pt nanocatalysts are prepared using different room temperature ionic liquids (RTILs) as the solvent and conventional preparation techniques, based on wet impregnation methods. The Pt/C nanocatalysts are characterized by XRD, TEM, EDX, and XPS. The results of the analyses show that the Pt/C catalysts, using different RTILs as solvents, are homogeneously dispersed with a narrow size distribution. The electro‐oxidation of liquid methanol on these catalysts is investigated at room temperature by cyclic voltammetry and chronoamperometry. The results have shown that the Pt/C catalysts prepared using RTILs are more active than the other Pt/C catalysts prepared by the authors. Surface area measurements of the Pt metal, conducted by electro‐oxidation of preadsorbed CO, indicate that catalysts prepared using RTILs as the solvents have higher surface area. The Pt/C nanocatalysts, prepared using RTILs, exhibit enhanced activity for the methanol oxidation reaction, compared with the Pt/C catalysts prepared by the impregnation method and commercial Pt/C catalysts.
BH3‐only proteins: Integrated control point of apoptosis
Authors: Shibue Tsukasa , Taniguchi Tadatsugu 
Published: March 2006

AbstractBcl‐2 family proteins play central roles in the regulation of most, if not all, apoptotic pathways, and hence this family plays a critical role in oncogenesis. The Bcl‐2 homology 3 (BH3)‐only members of this family are “proapoptotic,” promoting apoptosis by sensing cellular stresses: that is, they are activated or induced in response to stress stimuli. These BH3‐only proteins then interfere with the function of “prosurvival” Bcl‐2 family members, thereby promoting the progression of apoptosis. It has long been recognized that the induction and activation of each of the BH3‐only proteins are subject to the type of stress stimulus. Although it was originally assumed that all the BH3‐only proteins exert similar effects on the downstream apoptotic machinery, recent studies have uncovered their distinct functional properties, indicating the operation of more intricate, versatile control mechanisms of apoptosis. In this review, we will summarize recent findings on the diversity in the activation and function of BH3‐only proteins. In particular, we focus on the overlapping and individual roles of 2 BH3‐only proteins, Puma and Noxa, in the context of the apoptotic response induced by the tumor suppressor p53. © 2006 Wiley‐Liss, Inc.
IRS‐1–Rad51 nuclear interaction sensitizes JCV T‐antigen positive medulloblastoma cells to genotoxic treatment
Authors: Trojanek Joanna , Ho Thu , Croul Sidney , Wang Jin Ying , Chintapalli Janaki , Koptyra Mateusz , Giordano Antonio , Khalili Kamel , Reiss Krzysztof 
Published: March 2006

AbstractThe large T‐antigen from human polyomavirus JC (JCV T‐antigen) is suspected to play a role in malignant transformation. Previously, we reported that JCV T‐antigen requires the presence of a functional insulin‐like growth factor I receptor (IGF‐IR) for transformation of fibroblasts and for survival of medulloblastoma cell lines; that IGF‐IR is phosphorylated in medulloblastoma biopsies and that JCV T‐antigen inhibits homologous recombination‐directed DNA repair, causing accumulation of mutations. Here we are evaluating whether JCV T‐antigen positive and negative mouse medulloblastoma cell lines, which significantly differ in their tumorigenic properties, are also different in their abilities to repair double strand breaks of DNA (DSBs). Our results show that despite much stronger tumorigenic potential, JCV T‐antigen positive medulloblastoma cells are more sensitive to genotoxic agents (cisplatin and γ‐irradiation). Subsequent analysis of DNA repair of DSBs indicated that homologous recombination‐directed DNA repair (HRR) was selectively attenuated in JCV T‐antigen positive medulloblastoma cells. JCV T‐antigen did not affect HRR directly. In the presence of JCV T‐antigen, insulin receptor substrate 1 (IRS‐1) translocated to the nucleus where it co‐localized with Rad51, possibly attenuating HRR. © 2006 Wiley‐Liss, Inc.
Serum C‐peptide levels and breast cancer risk: Results from the European prospective investigation into cancer and nutrition (EPIC)
Authors: Verheus Martijn , Peeters Petra H.M. , Rinaldi Sabina , Dossus Laure , Biessy Carine , Olsen Anja , Tjønneland Anne , Overvad Kim , Jeppesen Majbritt , Clavel‐Chapelon Françoise , Téhard Bertrand , Nagel Gabriele , Linseisen Jakob , Boeing Heiner , Lahmann Petra H. , Arvaniti Athina , Psaltopoulou Theodora , Trichopoulou Antonia , Palli Domenico , Tumino Rosario , Panico Salvatore , Sacerdote Carlotta , Sieri Sabina , van Gils Carla H. , Bueno‐de‐Mesquita Bas H. , González Carlos A. , Ardanaz Eva , Larranaga Nera , Garcia Carmen Martinez , Navarro Carmen , Quirós J. Ramón , Key Tim , Allen Naomi , Bingham Sheila , Khaw Kay‐Tee , Slimani Nadia , Riboli Elio , Kaaks Rudolf 
Published: March 2006

AbstractIt has been hypothesized that chronic hyperinsulinemia, a major metabolic consequence of physical inactivity and excess weight, might increase breast cancer risk by direct effects on breast tissue or indirectly by increasing bioavailable levels of testosterone and estradiol. Within the European Prospective Investigation into Cancer and Nutrition (EPIC), we measured serum levels of C‐peptide—a marker for pancreatic insulin secretion—in a total of 1,141 incident cases of breast cancer and 2,204 matched control subjects. Additional measurements were made of serum sex hormone binding globulin (SHBG) and sex steroids. Conditional logistic regression models were used to estimate breast cancer risk for different levels of C‐peptide. C‐peptide was inversely correlated with SHBG and hence directly correlated with free testosterone among both pre and postmenopausal women. C‐peptide and free estradiol also correlated positively, but only among postmenopausal women. Elevated serum C‐peptide levels were associated with a nonsignificant reduced risk of breast cancer diagnosed up to the age of 50 years [odds ratio (OR) = 0.70, (95% confidence interval (CI), 0.39–1.24); ptrend = 0.05]. By contrast, higher levels of C‐peptide were associated with an increase of breast cancer risk among women above 60 years of age, however only among those women who had provided a blood sample under nonfasting conditions [OR = 2.03, (95% CI, 1.20–3.43); ptrend = 0.01]. Our results do not support the hypothesis that chronic hyperinsulinemia generally increases breast cancer risk, independently of age. Nevertheless, among older, postmenopausal women, hyperinsulinemia might contribute to increasing breast cancer risk. © 2006 Wiley‐Liss, Inc.
The antimicrobial peptide, lactoferricin B, is cytotoxic to neuroblastoma cells in vitro and inhibits xenograft growth in vivo
Authors: Eliassen Liv Tone , Berge Gerd , Leknessund Arild , Wikman Mari , Lindin Inger , Løkke Cecilie , Ponthan Frida , Johnsen John Inge , Sveinbjørnsson Baldur , Kogner Per , Flægstad Trond , Rekdal Øystein 
Published: March 2006

AbstractAntimicrobial peptides have been shown to exert cytotoxic activity towards cancer cells through their ability to interact with negatively charged cell membranes. In this study the cytotoxic effect of the antimicrobial peptide, LfcinB was tested in a panel of human neuroblastoma cell lines. LfcinB displayed a selective cytotoxic activity against both MYCN‐amplified and non‐MYCN‐amplified cell lines. Non‐transformed fibroblasts were not substantially affected by LfcinB. Treatment of neuroblastoma cells with LfcinB induced rapid destabilization of the cytoplasmic membrane and formation of membrane blebs. Depolarization of the mitochondria membranes and irreversible changes in the mitochondria morphology was also evident. Immuno‐ and fluorescence‐labeled LfcinB revealed that the peptide co‐localized with mitochondria. Furthermore, treatment of neuroblastoma cells with LfcinB induced cleavage of caspase‐6, ‐7 and ‐9 followed by cell death. However, neither addition of the pan‐caspase inhibitor, zVAD‐fmk, or specific caspase inhibitors could reverse the cytotoxic effect induced by LfcinB. Treatment of established SH‐SY‐5Y neuroblastoma xenografts with repeated injections of LfcinB resulted in significant tumor growth inhibition. These results revealed a selective destabilizing effect of LfcinB on two important targets in the neuroblastoma cells, the cytoplasmic‐ and the mitochondria membrane. © 2006 Wiley‐Liss, Inc.
Randomized controlled trial of human papillomavirus testing versus Pap cytology in the primary screening for cervical cancer precursors: Design, methods and preliminary accrual results of the Canadian cervical cancer screening trial (CCCaST)
Authors: Mayrand Marie‐Hélène , Duarte‐Franco Eliane , Coutlée François , Rodrigues Isabel , Walter Stephen D. , Ratnam Sam , Franco Eduardo L. ,   for the CCCaST Study Group
Published: March 2006

AbstractSince infection with oncogenic human papillomavirus (HPV) has been considered a necessary cause of cervical cancer, tests for oncogenic HPV types have been proposed as adjuncts or replacements to Pap cytology. We designed the Canadian Cervical Cancer Screening Trial (CCCaST) to compare the relative efficacy of HPV DNA testing and Pap cytology in primary screening for cervical cancer and its high‐grade precursors. CCCaST randomized women aged 30–69 years in Montreal (Quebec) and in St. John's (Newfoundland) to 1 of 2 screening groups: focus on Pap (conventional) or focus on HPV testing (Hybrid Capture 2). Women in both arms received both tests, but were randomized as to their order, the first test being the index test. Women with an abnormal Pap test or a positive HPV test underwent colposcopy and biopsy, as did a random sample of women with a negative index test. CCCaST enrolled 9,667 women between October 2002 and October 2004. At enrolment, 2.8% had an abnormal Pap test, 6.1% had a positive HPV test and 1.1% were abnormal in both tests. ASC‐US was the most frequent cytological abnormality, representing 64% of abnormal Pap results. The frequency of abnormal Pap and HPV results decreased with increasing age and the proportion of HPV‐positive results increased with the severity of Pap abnormality. Efficacy analysis will determine if the extra referrals with HPV DNA testing will translate into a relevant increase in high‐grade cervical cancer precursor detection. Because of its design, CCCaST will provide sound evidence for formulating cervical cancer screening strategies. © 2006 Wiley‐Liss, Inc.
Tissue array analysis of expression microarray candidates identifies markers associated with tumor grade and outcome in serous epithelial ovarian cancer
Authors: Ouellet Véronique , Guyot Marie‐Claude , Le Page Cécile , Filali‐Mouhim Abdelali , Lussier Christian , Tonin Patricia N. , Provencher Diane M. , Mes‐Masson Anne‐Marie 
Published: March 2006

AbstractMolecular profiling is a powerful approach to identify potential clinical markers for diagnosis and prognosis as well as providing a better understanding of the biology of epithelial ovarian cancer. On the basis of the analysis of HuFL expression data, we have previously identified genes that distinguish low malignant potential and invasive serous epithelial ovarian tumors. In this study, we used immunohistochemistry to monitor a subset of differently expressed candidates (Ahr, Paep, Madh3, Ran, Met, Mek1, Ccne1, Ccd20, Cks1 and Cas). A tissue array composed of 244 serous tumors of different grades (0–3) and stages (I–IV) was used in this analysis. All markers assayed presented differential protein expression between serous tumors of low and high grade. Significant differences in Ccne1 and Ran expression were observed in a comparison of low malignant potential and grade 1 tumor samples (p < 0.01). In addition, irrespective of the grade, Ccne1, Ran, Cdc20 and Cks1 showed significant differences of expression in association with the clinical stage of disease. While high level of Ccne1 have previously been associated with poor outcomes, here we found that high level of either Ran or Cdc20 appear to be more tightly associated with a poor prognosis (p < 0.001, 0.03, respectively). The application of these biomarkers in both the initial diagnosis and prognostic attributes of patients with epithelial ovarian tumors should prove to be useful in patient management. © 2006 Wiley‐Liss, Inc.
Sun exposure and host phenotype as predictors of cutaneous melanoma associated with neval remnants or dermal elastosis
Authors: Lee Eva Y. , Williamson Richard , Watt Peter , Hughes Maria Celia , Green Adèle C. , Whiteman David C. 
Published: March 2006

AbstractRecent research suggests that cutaneous melanomas may arise through 2 distinct pathways, characterized by chronic sun exposure on one hand and nevus‐prone phenotype of the host on the other. Two histological characteristics of melanoma consistent with these divergent origins are dermal elastosis in adjacent skin and neval remnants contiguous with the tumor, respectively. To further explore causal heterogeneity in melanoma, we compared sun exposure histories and phenotypic characteristics among a population‐based sample of patients newly diagnosed with cutaneous melanoma with and without contiguous neval remnants or dermal elastosis. Tissue blocks were obtained for 141 patients: 53 with superficial spreading melanoma (SSM) of the back, 42 with SSM of head and neck (H & N), and 39 and 7 with lentigo maligna/lentigo maligna melanoma (LM/LMM) of the H & N and back, respectively. Melanomas of the H & N were less likely than those on back to have neval remnants (adjusted OR 0.6, 95% CI 0.3–1.4), but were significantly more likely to have dermal elastosis (adjusted OR 9.3, 95% CI 3.5–25). In site‐specific analyses, we found that H & N melanomas with neval remnants were more likely than those without neval remnants to arise in people with more than 60 nevi (adjusted OR 2.1, 95% CI 0.3–14.3), but were less likely to arise in those with more than 20 actinic keratoses. Less marked associations were observed for melanomas of the back. High levels of sun exposure strongly predicted dermal elastosis for H & N melanomas (OR 22.5, 95% CI 2.1–245), but not for melanomas of the back (OR 2.1, 95% CI 0.4–11). We conclude that melanomas with different histologic characteristics have different risk factor profiles, particularly on the head and neck. These data accord with the hypothesis that melanomas arise through different causal pathways. © 2006 Wiley‐Liss, Inc.
Noninvasive diagnosis of nasopharyngeal carcinoma: Nasopharyngeal brushings reveal high Epstein‐Barr virus DNA load and carcinoma‐specific viral BARF1 mRNA
Authors: Stevens Servi J.C. , Verkuijlen Sandra A.W.M. , Hariwiyanto Bambang , Harijadi  , Paramita Dewi K. , Fachiroh Jajah , Adham Marlinda , Tan I. Bing , Haryana Sophia M. , Middeldorp Jaap M. 
Published: March 2006

AbstractNasopharyngeal carcinoma (NPC) is the most prevalent ENT‐tumour in Indonesia. We investigated the primary diagnostic value of Epstein‐Barr virus (EBV) DNA load and mRNA detection in noninvasive nasopharyngeal (NP) brushings, obtained prospectively from consecutive Indonesian ENT‐patients with suspected NPC (N = 106) and controls. A subsequent routine NP biopsy was taken for pathological examination and EBER‐RISH, yielding 85 confirmed NPC and 21 non‐NPC tumour patients. EBV DNA and human DNA load were quantified by real‐time PCR. NP brushings from NPC patients contained extremely high EBV DNA loads compared to the 88 non‐NPC controls (p < 0.0001). Using mean EBV DNA load in controls plus 3 SD as cut‐off value, specificity, sensitivity, positive and negative predictive values were 98, 90, 97 and 91%, respectively. Epstein‐Barr nuclear antigen 1 (EBNA1) and the carcinoma‐specific BARF1 mRNA were detected by nucleic acid sequence based amplification and found in 86 and 74% of NP brushings, confirming NPC tumour cell presence. EBV RNA positivity was even higher in fresh samples stored at −80°C until RNA expression analyses (88% for both EBNA1 and BARF1). EBV RNA‐negative NP brushings from proven NPC cases had the lowest EBV DNA loads, indicating erroneous sampling. No EBV mRNA was detected in NP brushings from healthy donors and non‐NPC patients. In conclusion, EBV DNA load measurement combined with detection of BARF1 mRNA in simple NP brushings allows noninvasive NPC diagnosis. It reflects carcinoma‐specific EBV involvement at the anatomical site of tumour development and reduces the need for invasive biopsies. This procedure may be useful for confirmatory diagnosis in large serological NPC screening programs and has potential as prognostic tool. © 2006 Wiley‐Liss, Inc.