Distributed closed-loop spatial multiplexing for uplink multiuser systems

Focusing on the uplink, where mobile users (each with a single transmit antenna) communicate with a base station with multiple antennas, we treat multiple users as antennas to enable spatial multiplexing across users. Introducing distributed closed-loop spatial multiplexing with threshold-based user selection, we propose two uplink channel-assigning strategies with limited feedback. We prove that the proposed system also outperforms the standard greedy scheme with respect to the degree of fairness, measured by the variance of the time averaged throughput. For uplink multi-antenna systems, we show that the proposed scheduling is a better choice than the greedy scheme in terms of the average BER, feedback complexity, and fairness. The numerical results corroborate our findings

Threshold-based substream selection for closed-loop spatial multiplexing

We propose a low-complexity closed-loop spatial multiplexing method with limited feedback over multi-input-multi-output (MIMO) fading channels. The transmit adaptation is simply performed by selecting transmit antennas (or substreams) by comparing their signal-to-noise ratios to a given threshold with a fixed nonadaptive constellation and fixed transmit power per substream. We analyze the performance of the proposed system by deriving closed-form expressions for spectral efficiency, average transmit power, and bit error rate (BER). Depending on practical system design constraints, the threshold is chosen to maximize the spectral efficiency (or minimize the average BER) subject to average transmit power and average BER (or spectral efficiency) constraints, respectively. We present numerical and Monte Carlo simulation results that validate our analysis. Compared to open-loop spatial multiplexing and other approaches that select the best antenna subset in spatial multiplexing, the numerical results illustrate that the proposed technique obtains significant power gains for the same BER and spectral efficiency. We also provide numerical results that show improvement over rate-adaptive orthogonal space-time block coding, which requires highly complex constellation adaptation. We analyze the impact of feedback delay using analytical and Monte Carlo approaches. The proposed approach is arguably the simplest possible adaptive spatial multiplexing system from an implementation point of view. However, our approach and analysis can be extended to other systems using multiple constellations and power levels.

Induction of alloxan/streptozotocin diabetes in dogs: a revised experimental technique

The diabetic dog represents an excellent model for use in many aspects of diabetic research. The present paper describes, in detail, a reproducible experimental protocol for the successful induction of chemical diabetes in beagles using a combination of the 2 pancreatic beta-cell cytoxic agents alloxan and streptozotocin.

Incubation or Induction? Gendered Identity Work in the Context of Technology Business Incubation

While there is a substantial body of literature exploring the influence of business incubation upon early stage firms, this debate remains almost entirely gender blind. This article challenges this assumption by adopting a feminist perspective to reveal business incubation as a gendered process shaping the identity work undertaken by women seeking legitimacy as technology venturers. In so doing, we critically evaluate prevailing normative analyses of the business incubation process and entrepreneurial legitimation. To illustrate this argument, we draw upon empirical evidence which reveals technology incubation as a legitimating induction process encouraging women to reproduce masculinized representations of the normative technology entrepreneur.

Induction of signalling in non-erythroid cells by pharmacological levels of erythropoietin

Erythropoiesis is maintained by the hormone erythropoietin (Epo) binding to its cognate receptor (EpoR) on erythroid progenitor cells. The Epo-EpoR interaction initiates a signal transduction process that regulates the survival, growth and differentiation of these cells. Originally perceived as highly lineage-restricted, Epo is now recognised to have pleiotropic effects extending beyond the maintenance of red cell mass. Functional interactions between Epo and EpoR have been demonstrated in numerous cells and tissues. EpoR expression on neoplastic cells leads to concern that recombinant human erythropoietin, used to treat anaemia in cancer patients, may augment tumour growth. Here we demonstrate that EPO, at pharmacological concentrations, can activate three major signalling cascades, viz. the Jak2/STAT5, Ras/ERK and PI3K/Akt pathways in non-small cell lung carcinoma (NSCLC) cell lines. EpoR synthesis is normally under the control of GATA-1, but NSCLC cells exhibit decreased GATA-1 levels compared to GATA-2, -3 and -6, suggesting that GATA-1 is not essential for EpoR production. The increased Epo-induced signalling was not associated with a growth advantage for the NSCLC cells.

TRACE observations of driven loop oscillations

Aims: On 13 June 1998, the TRACE satellite was fortuitously well placed to observe the effects of a flare-induced EIT wave in the corona, and its subsequent interaction with coronal magnetic loops. In this study, we use these TRACE observations to corroborate previous theoretical work, which determined the response of a coronal loop to a harmonic driver in the context of ideal magnetohydrodynamics, as well as estimate the magnetic field strength and the degree of longitudinal inhomogeneity. Methods: Loop edges are tracked, both spatially and temporally, using wavelet modulus maxima algorithms, with corresponding loop displacements from its quiescent state analysed by fitting scaled sinusoidal functions. The physical parameters of the coronal loop are subsequently determined using seismological techniques. Results: The studied coronal loop is found to oscillate with two distinct periods, 501 ± 5 s and 274 ± 7 s, which could be interpreted as belonging to the fundamental kink mode and first harmonic, or could reflect the stage of an overdriven loop. Additional scenarios for explaining the two periods are listed, each resulting in a different value of the magnetic field and the intrinsic and sub-resolution properties of the coronal loop. When assuming the periods belong to the fundamental kink mode and its first harmonic, we obtain a magnetic field strength inside the oscillating coronal loop of 2.0 ± 0.7 G. In contrast, interpreting the oscillations as a combination of the loop's natural kink frequency and a harmonic EIT wave provides a magnetic field strength of 5.8 ± 1.5 G. Using the ratio of the two periods, we find that the gravitational scale height in the loop is 73 ± 3 Mm. Conclusions: We show that the observation of two distinct periods in a coronal loop does not necessarily lead to a unique conclusion. Multiple plausible scenarios exist, suggesting that both the derived strength of the magnetic field and the sub-resolution properties of the coronal loop depend entirely on which interpretation is chosen. The interpretation of the observations in terms of a combination of the natural kink mode of the coronal loop, driven by a harmonic EIT wave seems to result in values of the magnetic field consistent with previous findings. Other interpretations, which are realistic, such as kink fundamental mode/first harmonic and the oscillations of two sub-resolution threads result in magnetic field strengths that are below the average values found before.

Efficient Drug Delivery and Induction of Apoptosis in Colorectal Tumors Using a Death Receptor 5-Targeted Nanomedicine

Death Receptor 5 (DR5) is a pro-apoptotic cell-surface receptor that is a potential therapeutic target in cancer. Despite the potency of DR5-targeting agents in preclinical models, the translation of these effects into the clinic remains disappointing. Herein, we report an alternative approach to exploiting DR5 tumor expression using antibody-targeted, chemotherapy-loaded nanoparticles. We describe the development of an optimized polymer-based nanotherapeutic incorporating both a functionalized polyethylene glycol (PEG) layer and targeting antibodies to limit premature phagocytic clearance whilst enabling targeting of DR5-expressing tumor cells. Using the HCT116 colorectal cancer model, we show that following binding to DR5, the nanoparticles activate caspase 8, enhancing the anti-tumor activity of the camptothecin payload both in vitro and in vivo. Importantly, the combination of nanoparticle-induced DR5 clustering with camptothecin delivery overcomes resistance to DR5-induced apoptosis caused by loss of BAX or overexpression of anti-apoptotic FLIP. This novel approach may improve the clinical activity of DR5-targeted therapeutics while increasing tumor-specific delivery of systemically toxic chemotherapeutics.Molecular Therapy (2014); doi:10.1038/mt.2014.137.

Biogas reforming using renewable wind energy and induction heating

While the benefits of renewable energy are well known and used to influence government policy there are a number of problems which arise from having significant quantities of renewable energies on an electricity grid. The most notable problem stems from their intermittent nature which is often out of phase with the demands of the end users. This requires the development of either efficient energy storage systems, e.g. battery technology, compressed air storage etc. or through the creation of demand side management units which can utilise power quickly for manufacturing operations. Herein a system performing the conversion of synthetic biogas to synthesis gas using wind power and an induction heating system is shown. This approach demonstrates the feasibility of such techniques for stabilising the electricity grid while also providing a robust means of energy storage. This exemplar is also applicable to the production of hydrogen from the steam reforming of natural gas.

VDR and MEK-ERK dependent induction of the antimicrobial peptide cathelicidin in keratinocytes by lithocholic acid

Cathelicidin is an antimicrobial peptide (AMP) and signaling molecule in innate immunity and a direct target of 1,25-dihydroxyvitamin D3 (1,25D3) in primary human keratinocytes (NHEK). The expression of cathelicidin is dysregulated in various skin diseases and its regulation differs depending on the epithelial cell type. The secondary bile acid lithocholic acid (LCA) is a ligand of the vitamin D receptor (VDR) and can carry out in vivo functions of vitamin D3. Therefore we analyzed cathelicidin mRNA- and peptide expression levels in NHEK and colonic epithelial cells (Caco-2) after stimulation with LCA. We found increased expression of cathelicidin mRNA and peptide in NHEK, in Caco-2 colon cells no effect was observed after LCA stimulation. The VDR as well as MEK-ERK signaled the upregulation of cathelicidin in NHEK induced by LCA. Collectively, our data indicate that cathelicidin induction upon LCA treatment differs in keratinocytes and colonic epithelial cells. Based on these observations LCA-like molecules targeting cathelicidin could be designed for the treatment of cutaneous diseases that are characterized by disturbed cathelicidin expression.