Cellular system

We develop an unsupervised approach to condition monitoring of cellular networks using competitive neural algorithms. Training is carried out with state vectors representing the normal functioning of a simulated CDMA2000 network. Once training is completed, global and local normality profiles (NPs) are built from the distribution of quantization errors of the training state vectors and their components, respectively. The global NP is used to evaluate the overall condition of the cellular system. If abnormal behavior is detected, local NPs are used in a component-wise fashion to find abnormal state variables. Anomaly detection tests are performed via percentile-based confidence intervals computed over the global and local NPs. We compared the performance of four competitive algorithms (WTA, FSCL, SOM and Neural-Gas) and the results suggest that the joint use of global and local NPs is more efficient and more robust than current single-threshold methods. and Wideband CDMA, respectively, which are 3G technologies capable of providing speeds of up to 2Mbits/sec. 2 CDMA2000, also called 1xRTT (single carrier radio transmission technology), is a 3G wireless technology based on the CDMA platform which has the capability of providing speeds of up to 144 Kbps.

Ihe paper describes a simplified structure concerning the implmnentation of an adaptive digital receiver suitable for the pan-european cellular system (GSM Group Special Mobile). In the GSM system, the performance of the received information is strongly affected by the multipath typical of the mobile communications channel. lke proposed maximum likelihood sequence estimation (MLSE) receiver based on the Viterbi algorithm compensates for selective distortion due to the multipath propagation and Doppler shifr also in the case of fast channel variations using an adaptive tracking mode method.

Aging is associated to a decline in immune functions that are in part related to a defective protein kinase C dependent signal transduction machinery. RACK-1 (Receptor for Activated C Kinase 1) is a scaffold protein for different kinases and membrane receptors. We have previously demonstrated, in the elderly, a defective PCKβII (Protein Kinase C βII) translocation related to a decrease in RACK-1 protein expression, which is correlated to the age-associated decline in DHEA (dehydroepiandrosterone) levels. As a consequence of this signal transduction impairment, a significant decrease in immune cells functionality was observed. Furthermore, we could demonstrate that in vivo and in vitro DHEA administration restored RACK-1 level and immune functions, indicating that this hormone behaved as a positive RACK-1 regulator. We have most recently characterized the human GNB2L1 promoter region, coding for RACK-1 protein. Although no direct DHEA responsive elements were found, a glucocorticoid responsive element (GRE) was identified. The purpose of this work was to investigate, in the human pro-myelocytic cell line THP-1, whether physiological cortisol concentrations were able to modulate GNB2L1 promoter activity, RACK-1 transcription as well as cytokine production. As DHEA is endowed of anti-glucocorticoid properties in several cellular systems, and as cortisol:DHEA ratio imbalance is relevant in aging, we also investigated their possible interaction at the RACK-1 expression level. We could demonstrate that cortisol acted in a dose-related manner as a GNB2L1 promoter repressor, reducing RACK-1 mRNA expression and protein level. Probably by interfering with glucocorticoid receptor binding to GRE sequence, prolonged DHEA exposure counteracted cortisol effects, restoring RACK-1 levels and cytokine production, as assessed by LPS-induced TNF-α release.

Embryonic stem cells, totipotent cells of the early mouse embryo, were established as permanent cell lines of undifferentiated cells. ES cells provide an important cellular system in developmental biology for the manipulation of preselected genes in mice by using the gene targeting technology. Embryonic stem cells, when cultivated as embryo-like aggregates, so-called ‘embryoid bodies’, are able to differentiate in vitro

Cytomics aims to determine the molecular phenotype of single cells. Within the context of the -omics, cytomics allows the investigation of multiple biochemical features of the heterogeneous cellular systems known as the cytomes. Cytomics can be considered as the science of single cell-based analyses that links genomics and proteomics with the dynamics of cell and tissue function, as modulated by external inXuences. Inherent to cytomics are the use of sensitive, scarcely invasive, Xuorescence-based multiparametric methods and the event-integrating concept of individual cells to understand the complexity and behaviour of tissues and organisms. Among cytomic technologies, Xow cytometry, confocal laser scanning microscopy and laser capture microdissection are of great relevance. Other recent technologies based on single cell bioimaging and bioinformatic tools become important in drug discovery and toxicity testing, because of both highcontent and high-troughput. The multiparametric capacity of cytomics is very useful for the identiWcation, characterization and isolation of stem cell populations. In our experience, Xow cytometry is a powerful and versatile tool that allows quantitative analysis of single molecules, prokaryotic and eukaryotic cells for basic, biotechnological, environmental and clinical studies. The dynamic nature of cytomic assays leads to a real-time kinetic approach based on sequential examination of diVerent single cells from a population undergoing a dynamic process, the in Xuxo level. Finally, cytomic technologies may provide in vitro methods alternative to laboratory animals for toxicity assessment.

Catastrophic events including those sparked by terrorism have cast a pall over society in recent years. Events such as September 11th or the bombing of the Alfred P. Murrah Federal Building in Okalahoma City demonstrated a sudden surge in telephone call volume. These events indicated that communications systems, including cellular, can fail as a result from damage or capacity overload. Cellular systems have significant capacity given the limited radio spectrum allocated but much like airlines that oversell seats because inevitably some passengers do not show up, cellular providers typically have more customers than operational spectrum can handle in aggregate. Normally this is perfectly acceptable because a high percentage of the customer base would never be making calls simultaneously; except in an emergency. Such emergencies can be active or passive in nature. The release of dangerous airborne agents is one such scenario. The purpose of this study was to use a portable air particulate sensor as a data acquisition platform to evaluate the capability of real-time data throughput using existing wireless topologies, Java, eXtensible Markup Language (XML) and Internet protocols when cellular transmission frequencies are compromised. Results show that high levels of cellular voice traffic in a given area can hamper simultaneous data communications; however, Low Earth Orbiting Satellites (LEOS) can provide redundancy.

This paper provides an overview of cellular networks and wireless Internet. It focuses on the problems of providing multimedia services over these networks, and highlights the latest developments in the area. This is done by providing brief descriptions, and providing a wealth of pointers to where the relevant information can be obtained. The paper consists of four main sections corresponding to protocol layering: wireless data link layer for cellular systems and the supporting of multimedia in these environments; wireless network layer, namely Mobile IP needed to support mobility in a wireless Internet; wireless transport layer, namely the extensions to Internet's TCP; wireless application layer. Regarding cellular systems, we present an overview of multiple access techniques, transmission aspects, and quality of service issues in the data link layer of these systems. The section on wireless network layer provides a brief introduction to the Internet technologies, then it illustrates the deficiencies of the current Internet Protocol (IP) for supporting wireless/mobile applications and shows how the new Mobile IP protocol overcomes these deficiencies, and how mobility is handled in these wireless Internets. The next section tackles the problem of reliable communication in wireless Internet, and the related problems of TCP over Mobile IP. The final section focuses on application layer issues in wireless data, namely handover and developing Web applications for mobile computers.

This article proposes a method that can calculate the blocking probability of multi-service cellular systems with Wideband Code Division Multiple Access radio interface. The method considers a finite and an infinite source population and takes into account the interdependency of calls service processes in neighboring cells and in both the uplink and the downlink directions. The basis of the proposed method is the fixedpoint methodology. A comparison of the results of analytical calculations to those of simulations confirms the accuracy of the proposed method. The proposed scheme can realize cost-effective radio resource management in 3G mobile networks and can be easily applied to network capacity calculations.

1. The pathogenesis of the selective degeneration of the dopaminergic neurons in Parkinson's disease is still enigmatic. Recently we have shown that dopamine can induce apoptosis in postmitotic neuronal cells, as well as in other cellular systems, thus suggesting a role for this endogenous neurotransmitter and associated oxidative stress in the neuronal death process. 2. Dopamine has been shown to be capable of inducing DNA damage through its oxidative metabolites. p53 is a transcription factor that has a major role in determining cell fate in response to DNA damage. We therefore examined the possible correlation between dopamine-triggered apoptosis, DNA damage and levels of total phosphorylated p53 protein in cultured mouse cerebellar granule neurons. 3. Marked DNA damage and apoptotic nuclear condensation and fragmentation were detected within several hours of exposure to dopamine. An associated marked threefold increase in p53 phosphorylation was observed within this time window. Using a temperature-sensitive p53 activation system in leukemia LTR6 cells, were found that p53 inactivation dramatically attenuated dopamine toxicity. 4. We therefore conclude that DNA damage and p53 activation may have a role in mediating dopamine-induced apoptosis. Modulation of the p53 system may therefore have a protective role against the toxicity of this endogenous neurotransmitter and associated oxidative stress.

Hexavalent chromium is the major terrestrial pollutant released from electroplating industries, tanneries, thermal power plants and sewage. Cr(VI) is reported genotoxicant in vertebrates. Sub-lethal level of Cr(VI) can cause DNA damage. Earthworms are ecologically important soil invertebrates, used for ecotoxicological studies. In present study coelomocytes of Dichogaster curgensis were used for assessing Cr(VI) genotoxicity using single cell gel electrophoresis [(SCGE) i.e. comet assay] following in vitro and in vivo exposures. Cr(VI) produces reactive oxygen species (ROS) in the cellular system, which can be a major cause of DNA damage. Dose dependent DNA damage was observed during in vitro exposure, while in vivo exposure showed increasing DNA damage till 30 ppm in terms of arbitrary units and unexpected decrease in arbitrary units at 70 and 100 ppm of Cr(VI). It is speculated that the decrease in arbitrary units at higher concentrations might be due to lower DNA mobility, caused by formation of different types of cross-links.

Anomaly detection is a pattern recognition task whose goal is to report the occurrence of abnormal or unknown behavior in a given system being monitored. In this paper we propose a general procedure for the computation of decision thresholds for anomaly detection in mobile communication networks. The proposed method is based on Kohonen's Self-Organizing Map (SOM) and the computation of nonparametric (i.e. percentile-based) confidence intervals. Through simulations we compare the performance of the proposed and standard SOM-based anomaly detection methods with respect to the false positive rates produced.

There is an explosive growth in the market of wireless communications services in urban areas. New regulatory environments as well as competition in the communications industry require that these systems be deployed quickly and at low cost. Computer-based radio propagation prediction tools are strong candidates for this goal. In this paper, we introduce an outdoor radio propagation prediction tool using a ray tracing technique in two dimensions (2-D) and three dimensions (3-D). We have compared the predicted and measured results in various propagation environments. Comparisons indicate that 2-D is adequate for a low transmitter while 3-D is recommended for a high transmitter whose height is comparable with or higher than surrounding buildings. In most locations, the computer tool predicts the correct propagation loss with a mean error of less than 7 dB and a standard deviation of less than 8 dB. He is now in the Special Study Division at AT&T Laboratories, Holmdel, NJ. His research interests cover the characterization and modeling of communication channels, communication system performance analysis, propagation modeling of radio waves in buildings and urban environments, wireless communication system design including cellular, PCS, wireless LAN systems, RF communication through power lines, and electromagnetic theory.

The current 3GPP working assumption on the Evolved Universal Terrestrial Radio Access (E-UTRA) physical layer is that it will be based on single carrier frequency division multiple access (SC-FDMA) for the uplink and orthogonal frequency division multiple access (OFDMA) for the downlink. According to the concept specification, inter-cell interference mitigation techniques applicable to SC-FDMA and OFDMA systems are expected to be the key radio resource management techniques for E-UTRA. In this paper we propose and analyze a simple reuse partitioning technique (assuming coordinated subcarrier allocation in the cells) that is able to minimize intercell interference. We propose a model that is able to take into account that sessions dynamically enter and leave the system. Rigid sessions require a class-specific fixed number of subcarriers, while elastic sessions can enter the system if a minimum number of sub-carriers is allocated to them. In this rather general setting we analyze the system performance in terms of the expected number of sub-carrier collisions, the session blocking probabilities and the signal-to-noise-and-interference ratio performance. We present numerical results on the various trade-offs between these measures that provide insight into the behavior of OFDM based cellular systems and help dimension the parameters of a reuse partitioned system.

V ery few technologies have had as much impact on the trajectory of evolution of wireless communication systems as Multiple Input Multiple Output (MIMO) systems. MIMO systems have already been employed in the existing 802.11n and 802.16e standards resulting in a huge leap in their achievable rates. A relatively recent idea of extending the benefits of MIMO systems to multi-user scenarios seems promising in the context of achieving high data rates envisioned for future cellular standards after 3G. Although substantial research has been done on the theoretical front, recent focus is on making multi user MIMO (MU-MIMO) practically realizable. It offers an enormous scope for further research in the coming years. As in the case of any evolving technology in communication systems, the literature concerning MU-MIMO systems involves complex mathematical analysis, making it difficult for an ordinary reader to comprehend. This article aims at giving an insight into MU-MIMO systems-its concept, fundamentals, and trends including an overview of important research results. It is intended at giving a good start to amateurs interested in being part of the community that shapes the future of wireless systems.

In this paper, we study the capacity of cellular systems with interference-adaptation dynamic channel allocation (DCA) through a set of heuristics that evaluate the required number of channels for some mobile traffic pattern. In particular, we evaluate the improvement in the reuse factor given the knowledge of the mobiles' locations. Assuming that the mobiles' locations are sampled from the uniform random distribution or are fixed on a uniform grid, we show the effect of a number of parameters, such as the number of mobiles per cell, the minimum allowable signal-to-interference ratio, and the limited knowledge of mobiles' locations. We also investigate the effect of shadow fading and signal-based power control. Although previous papers have proposed various heuristics with varying performance, here we present heuristics that are shown to give the maximum packing results based on our assumptions. In particular, the single-interferer assumption, used throughout our work, is justified and the optimality of the square-root signalbased power control is proven.

The continuation of an active call is one of the most important quality measurements in cellular systems. Handoff process enables a cellular system to provide such a facility by transferring an active call from one cell to another. Different approaches are proposed and applied in order to achieve better handoff service. The principal parameters used to evaluate handoff techniques are: Forced termination probability and call blocking probability. Mechanisms such as guard channels and queuing handoff calls decrease the forced termination probability while increasing the call blocking probability. In this paper we present an overview about the issues related to handoff initiation and decision and discuss about different types of handoff techniques available in the literature.

He is engaged in research and teaching in digital communications and wireless systems, equalization and channel estimation in multicarrier (OFDM) communication systems, and efficient modulation and coding techniques (TCM and turbo coding). He spent two years (1979-

LTE represents an emerging and promising technology for providing broadband ubiquitous Internet access. For this reason, several research groups are trying to optimize its performance. Unfortunately, at the present, to the best of our knowledge, no open source simulation platforms, that the scientific community can use to evaluate the performance of the entire LTE system, are freely available. The lack of a common reference simulator does not help the work of researchers and poses limitations on the comparison of results claimed by different research groups. To bridge this gap, herein, the open source framework LTE-Sim is presented to provide a complete performance verification of LTE networks. LTE-Sim has been conceived to simulate uplink and downlink scheduling strategies in multi-cell/multi-users environments taking into account user mobility, radio resource optimization, frequency reuse techniques, AMC module, and other aspects very relevant for industrial and scientific communities. The effectiveness of the proposed simulator has been tested and verified considering (i) the software scalability test which analyzes both memory and simulation time requirements; (ii) the performance evaluation of a realistic LTE network providing a comparison among wellknown scheduling strategies.

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Parkinson’s disease (PD) is a common neurodegenerative disorder. Neuronal cell death in PD is still poorly understood, despite a wealth of potential pathogenic mechanisms and pathways. Defects in several cellular systems have been implicated as early triggers that start cells down the road toward neuronal death. These include abnormal protein accumulation, particularly of alpha-synuclein; altered protein degradation via multiple pathways; mitochondrial dysfunction; oxidative stress; neuroinflammation; and dysregulated kinase signaling. As dysfunction in these systems mounts, pathways that are more explicitly involved in cell death become recruited. These include JNK signaling, p53 activation, cell cycle re-activation, and signaling through bcl-2 family proteins. Eventually, neurons become overwhelmed and degenerate; however, even the mechanism of final cell death in PD is still unsettled. In this review, we will discuss cell death triggers and effectors that are relevant to PD, highlighting important unresolved issues and implications for the development of neuroprotective therapies.

A design of the code-division multiple access (CDMA) cellular system architecture is presented. The base station architecture is based on a universal platform that can support CDMA and other cellular standards such as AMPS and TDMA in the same base station. The mobile switching center (MSC) architecture is enhanced to support the various CDMA system features such as soft handoff and variable bit rate vocoding. In particular, the digital cellular switch (DCS) at the MSC provides a frame relay packet switching interface to the base station. It is shown that such a packet switching interface can support more voice channels that the conventional DS0/DS1 circuit switching interface and is an essential element in achieving the soft handoff capability

An EHF satellite system for land-mobile applications to be integrated with a terrestrial cellular system is described in the paper. An approach to evaluate the carrier-tocochannel interference occurring in a multispot satellite COVerage adopting frequency reuse is introduced and results from the analysis are shown. Criteria for spectrum efficiency evaluation are also outlined along with traffic and link budget estimates. Possible options for payload implementation and mobile terminal design are presented.

A role for DTD in the bioreductive activation of mitomycin C was supported by indirect evidence utilizing enzyme inhibitors in cellular systems. Using a cell-free system, we have confirmed that DTD can bioactivate mitomycin C using both purified rat and human DTD. Metabolism and bioactivation of mitomycin C by DTD is pH-dependent. At pH 7.8 alkylation of DTD leading to enzyme inhibition and DTD crosslinking occurs whereas at pH values of 7.4 and below metabolite formation, preservation of catalytic activity of DTD and sequence-selective DNA crosslinking occurs. Bioactivation of mitomycin C by DTD and the cytotoxicity of this drug in DTD-rich cell lines is oxygen-independent. Mitomycin C induces greater DNA crosslinking, even after chemical reduction, at lower pH values. This suggests that if mitomycin C is used in tumors with elevated DTD activity, greater therapeutic activity may be obtained by lowering intratumoral pH. Human NSCLC has elevated DTD activity relative to SCLC and normal lung and may be a target for the development of drugs which can be efficiently bioactivated by DTD. Because of the pH-dependent inactivation of DTD by mitomycin C, however, other drugs which are efficiently metabolized and bioactivated by DTD may be better candidates for the therapy of tumors high in DTD such as NSCLC.

Insulin resistance is an important feature of type 2 diabetes and obesity. The underlying mechanisms of insulin resistance are still unclear and may involve pathological changes in multiple tissues. Mitochondrial dysfunction, including mitochondrial loss and over-production of oxidants, has been suggested to be involved in the development of insulin resistance. Increasing evidence suggests that targeting mitochondria to protect mitochondrial function as a unique measure, i.e. mitochondrial medicine, could prevent and ameliorate various diseases associated with mitochondrial dysfunction. In this review, we have summarized recent progress in pharmaceutical and nutritional studies of drugs and nutrients to targeting mitochondria by stimulating mitochondrial metabolism (biogenesis and degradation) to improve mitochondrial function and decrease oxidative stress for preventing and ameliorating insulin resistance. We have focused on nutrients from natural sources to stimulating mitochondrial biogenesis in cellular systems and in animal models. The in vitro and in vivo studies, especially our own work on the effects and mechanisms of mitochondrial targeting nutrients or their combinations, may help us to understand the importance and mechanisms of mitochondrial biogenesis in insulin resistance, and provide hope for developing mitochondria-targeting agents for preventing and treating insulin resistance in type 2 diabetes and obesity.

The outage probability of maximal ratio combining diversity with an arbitrary number of antennas in the presence of an arbitrary number of cochannel interferers and thermal noise is derived when the branch gains of the desired user signal and interfering signals experience Rayleigh fading and have the same correlation matrix. Two special cases, when the correlation matrix is equicorrelated and when the correlation matrix has different eigenvalues, are considered for both the equal-power cochannel interference case and the unequal-power cochannel interference case. Further, the average bit-error rate of a coherent binary phase-shift keying (BPSK)-modulated cellular system using maximal ratio combining diversity in cochannel interference and correlated Rayleigh fading is derived. The effects of the average signal-to-noise ratio (SNR) and the average signal-power-to-interference-power ratio on the system performance are examined.

Alterations in the antioxidant cellular system have often been proposed as biomarkers of pollutant-mediated toxicity. This study evaluated the effects of mercury on oxidative stress biomarkers and bioaccumulation in the liver, gills, white muscle and heart of the freshwater fish matrinxã, Brycon amazonicus, exposed to a nominal and sub-lethal concentration (~20% of 96 h-LC50) of 0.15 mg L−1 of mercury chloride (HgCl2) for 96 h in a static system. Increases in superoxide dismutase, catalase, glutathione peroxidase (GPx), glutathione S-transferase (GST) and glutathione reductase (GR) were observed in all tissues after HgCl2 exposure, except for white muscle GR activity and hepatic GPx. In the liver and gills, the exposure to HgCl2 also induced significant increases in reduced glutathione (GSH). Conversely, exposure to HgCl2 caused a significant decrease in the GSH levels and an increase in the oxidized glutathione (GSSG) content in the white muscle, while both GSH and GSSG levels increased significantly in the heart muscle. Metallothionein concentrations were significantly high after HgCl2 exposure in the liver, gills and heart, but remained at control values in the white muscle. HgCl2 exposure induced oxidative damage, increasing the lipid peroxidation and protein carbonyl content in all tissues. Mercury accumulated significantly in all the fish tissue. The pattern of accumulation follows the order gills > liver ≫ heart > white muscle. In conclusion, these data suggest that oxidative stress in response to inorganic mercury exposure could be the main pathway of toxicity induced by this metal in fish.

We propose a new approach to fault detection and diagnosis in third-generation (3G) cellular networks using competitive neural algorithms. For density estimation purposes, a given neural model is trained with data vectors representing normal behavior of a CDMA2000 cellular system. After training, a normality profile is built from the sample distribution of the quantization errors of the training vectors. Then, we find empirical confidence intervals for testing hypotheses of normal/abnormal functioning of the cellular network. The trained network is also used to generate inference rules that identify the causes of the faults. We compare the performance of four neural algorithms and the results suggest that the proposed approaches outperform current methods.

The dispersal units of plants are seeds but pollen is also dispersed and there are many similarities to be found between these two types of diaspores, especially in their environmental interactions. The economy of natural processes suggests that Nature would not “re-invent the wheel” and indeed there are many similarities, if not identical types of mechanisms, in the metabolic activities

We introduce the concept of the double-directional mobile radio channel. It is called this because it includes angular information at both link ends, e.g., at the base station and at the mobile station. We show that this angular information can be obtained with synchronized antenna arrays at both link ends. In wideband high-resolution measurements, we used a switched linear array at the receiver and a virtual-cross array at the transmitter. We evaluated the raw measurement data with a technique that alternately used estimation and beamforming, and that relied on ESPRIT (Estimation of Signal Parameters via Rotational Invariance Techniques) to obtain isuperresolution in both angular domains and in the delay domain. In sample microcellular scenarios (open and closed courtyard, line-of-sight and obstructed line-of-sight), up to 50 individual propagation paths were determined. The major multipath components could be matched precisely to the physical environment by geometrical considerations. Up to three reflectionlscattering points per .propagation path were identified and localized, lending insight into the multipath spreading properties in a microcell. The extracted multipath parameters allow unambiguous scatterer identification and channel characterization, independently of a specific antenna, its configuration (single/array), and its pattern. The measurement results demonstrated a considerable amount of power being carried via multiply reflected components, thus suggesting revisiting the popular single-bounce propagation models. It turned out that the wideband double-directional evaluation is a most complete method for separating multipath components. Due to its excellent spatial resolution, the double-directional concept provides accurate estimates of the channel's multipath-richness, which is the important parameter for the capacity of multiple-input multiple-output (MIMO) channels.

Background Obtaining reliable and reproducible two-color microarray gene expression data is critically important for understanding the biological significance of perturbations made on a cellular system. Microarray design, RNA preparation and labeling, hybridization conditions and data acquisition and analysis are variables difficult to simultaneously control. A useful tool for monitoring and controlling intra- and inter-experimental variation is Universal Reference RNA (URR), developed with the goal of providing hybridization signal at each microarray probe location (spot). Measuring signal at each spot as the ratio of experimental RNA to reference RNA targets, rather than relying on absolute signal intensity, decreases variability by normalizing signal output in any two-color hybridization experiment. Results Human, mouse and rat URR (UHRR, UMRR and URRR, respectively) were prepared from pools of RNA derived from individual cell lines representing different tissues. A variety of microarrays were used to determine percentage of spots hybridizing with URR and producing signal above a user defined threshold (microarray coverage). Microarray coverage was consistently greater than 80% for all arrays tested. We confirmed that individual cell lines contribute their own unique set of genes to URR, arguing for a pool of RNA from several cell lines as a better configuration for URR as opposed to a single cell line source for URR. Microarray coverage comparing two separately prepared batches each of UHRR, UMRR and URRR were highly correlated (Pearson's correlation coefficients of 0.97). Conclusion Results of this study demonstrate that large quantities of pooled RNA from individual cell lines are reproducibly prepared and possess diverse gene representation. This type of reference provides a standard for reducing variation in microarray experiments and allows more reliable comparison of gene expression data within and between experiments and laboratories.

This paper addresses the performance of Spatial Division Multiplexing (SDM) Multiple-input Multiple-output (MIMO) techniques together with Frequency Domain Packet Scheduling (FDPS) in both theory and practice. We start with a theoretical analysis under some ideal assumptions to derive the performance bounds of SDM-FDPS. To facilitate the analysis, a unified SINR concept is utilized to make a fair comparison of MIMO schemes with different number of spatial streams. The effect of packet scheduling is included in the post-scheduling SINR distribution using an analytical model. Based on that, the performance bounds are obtained with a more realistic SINR to throughput mapping metric. The system-level performance of SDM-FDPS has been evaluated under practical constraints using detailed simulations based on the UTRAN Long Term Evolution (LTE) downlink cellular system framework. The purpose is to investigate the impact of realistic factors on performance. Results confirm that the combination of SDM and FDPS can increase the spectral efficiency significantly, particularly in a micro-cell scenario, and up to 30%-60% gain is observed over 1x2 with FDPS depending on the traffic models considered. Finally, the more practical simulation results are compared against the theoretical performance bounds. A performance loss is seen in the simulations due to realistic coding/modulation, impact of frequency selectivity, signalling constraints, imperfect channel quality indicator (CQI), etc.

Wireless access to Internet services will become typical, rather than the exception as it is today. Such a vision presents great demands on mobile networks. Mobile IP represents a simple and scalable global mobility solution but lacks the support for fast handoff control and paging found in cellular telephony networks. In contrast, second-and third-generation cellular systems offer seamless mobility support but are built on complex and costly connection-oriented networking infrastructure that lacks the inherent flexibility, robustness, and scalability found in IP networks. In this article we present Cellular IP, a micro-mobility protocol that provides seamless mobility support in limited geographical areas. Cellular IP, which incorporates a number of important cellular system design principles such as paging in support of passive connectivity, is built on a foundation of IP forwarding, minimal signaling, and soft-state location management. We discuss the design, implementation, and evaluation of a Cellular IP testbed developed at Columbia University over the past several years. Built on a simple, low-cost, plug-and-play systems paradigm, Cellular IP software enables the construction of arbitrary-sized access networks scaling from picocellular to metropolitan area networks. The source code for Cellular IP is freely available from the Web (comet.columbia.edu/cellularip).

Cellular systems are generally robust against fluctuations of intracellular parameters such as gene expression level. However, little is known about expression limits of genes required to halt cellular systems. In this study, using the fission yeast Schizosaccharomyces pombe, we developed a genetic 'tug-of-war' (gTOW) method to assess the overexpression limit of certain genes. Using gTOW, we determined copy number limits for 31 cell-cycle regulators; the limits varied from 1 to 4100. Comparison with orthologs of the budding yeast Saccharomyces cerevisiae suggested the presence of a conserved fragile core in the eukaryotic cell cycle. Robustness profiles of networks regulating cytokinesis in both yeasts (septation-initiation network (SIN) and mitotic exit network (MEN)) were quite different, probably reflecting differences in their physiologic functions. Fragility in the regulation of GTPase spg1 was due to dosage imbalance against GTPase-activating protein (GAP) byr4. Using the gTOW data, we modified a mathematical model and successfully reproduced the robustness of the S. pombe cell cycle with the model.

We study a cellular system scenario where multiple data streams originating from a base station (BS) targeted to multiple cell-edge mobile stations (MSs) are transmitted via preinstalled cooperative relay stations (RSs) with multiple antennas. Our objective is to guarantee quality-of-service (QoS) in terms of predefined signal-to-noise ratio at such users within the transmit power budgets at BS and RSs while minimizing total transmit power. We propose a novel precoder design method for power allocation between multiple data streams at BS and RS by using joint zero-forcing strategy in order to avoid multiuser interference (MUI) in the signal received by MSs via both the direct and relay links. We also propose low-complexity suboptimal power allocation algorithm. We focus on analyzing the significance of direct link transmission in providing QoS to celledge MSs specially when RS is not situated directly between BS and MSs. Simulation results show that considering direct link and using the proposed scheme in such case significantly improves system outage performance compared to existing schemes in the literature which do not consider direct link.

Heat shock proteins (Hsp) form the most ancient defense system in all living organisms on earth. These proteins act as molecular chaperones by helping in the refolding of misfolded proteins and assisting in their elimination if they become irreversibly damaged. Hsp interact with a number of cellular systems and form efficient cytoprotective mechanisms. However, in some cases, wherein it is better if the cell dies, there is no reason for any further defense. Programmed cell death is a widely conserved general phenomenon helping in many processes involving the reconstruction of multicellular organisms, as well as in the elimination of old or damaged cells. Here, we review some novel elements of the apoptotic process, such as its interrelationship with cellular senescence and necrosis, as well as bacterial apoptosis. We also give a survey of the most important elements of the apoptotic machinery and show the various modes of how Hsp interact with the apoptotic events in detail. We revi...

Ph: 9 1-80-309-2658, Fax: 9 1-80-360-099 1 [email protected] Abstruct-Dynamic Channel allocation in Cellular Networks have become very popular off late due to the flexibility obtained by using any of the available channels in any cell as long as the Interference level is below a given threshold.

We demonstrate how virtual MIMO techniques can be implemented in a next-generation mobile communication system. In order to test basic principles, joint spatiotemporal processing of two users has been implemented in an uplink scenario. A prerequisite of virtual MIMO is accurate synchronization. It is shown that the carrier frequency offset can be reduced to a few Hz only at small signal-to-noise ratios. Based on remote synchronization via the downlink, a technique called frequency advance is applied ...

The integrated cellular ad hoc relaying (iCAR) system is a representative heterogeneous wireless system, proposed to address the congestion problem in the wireless networks. In this paper, we present an analytic model based on Markov chains for the queuing delay performance of iCAR. Our results show that the new call requests in iCAR have a significantly lower queuing delay than

Neo-Darwinists have long held that random mutations produce genetic differences among individuals, and selection increases the frequency of advantageous alleles. 1 In 1988, Cairns et al. claimed that an environmental pressure can cause advantageous mutations to occur in specific genes to alleviate that particular pressure. Directed mutation, as proposed by Cairns, has been all but eradicated from evolutionary thinking. However, more than a decade of research spurred by the Cairns et al. paper has cast doubt on three neo-Darwinian principles: (1) mutations occur independently of the environment, (2) mutations are due to replication errors, and (3) mutation rates are constant. This mini-review explores the history of the controversy and the decade of research that followed so as to place it in an evolutionary context. Several of the cellular mechanisms and models that explain the increased genetic diversity in populations experiencing adverse environmental pressure are described. In most cases it is clear that the increased genetic diversity is due to breakdowns of cellular machinery or alleles evolved for a purpose other than increasing genetic diversity, rather than to cellular systems that have been evolutionarily selected to increase the genetic diversity in times of stress.