Frequency-aware rate adaptation and MAC protocol

There has been burgeoning interest in wireless technologies that can use wider frequency spectrum. Technology advances, such as 802.11n and ultra-wideband (UWB), are pushing toward wider frequency bands. The analog-to-digital TV transition has made 100-250 MHz of digital whitespace bandwidth available for unlicensed access. Also, recent work on WiFi networks has advocated discarding the notion of channelization and allowing all nodes to access the wide 802.11 spectrum in order to improve load balancing. This shift towards wider bands presents an opportunity to exploit frequency diversity. Specifically, frequencies that are far from each other in the spectrum have significantly different SNRs, and good frequencies differ across sender-receiver pairs. This paper presents FARA, a combined frequency-aware rate adaptation and MAC protocol. FARA makes three departures from conventional wireless network design: First, it presents a scheme to robustly compute per-frequency SNRs using normal data transmissions. Second, instead of using one bit rate per link, it enables a sender to adapt the bitrate independently across frequencies based on these per-frequency SNRs. Third, in contrast to traditional frequency-oblivious MAC protocols, it introduces a MAC protocol that allocates to a sender-receiver pair the frequencies that work best for that pair. We have implemented FARA in FPGA on a wideband 802.11-compatible radio platform. Our experiments reveal that FARA provides a 3.1x throughput improvement in comparison to frequency-oblivious systems that occupy the same spectrum.Industrial Technology Research InstituteNational Science Foundation (U.S.)

Omics-based molecular techniques in oral pathology centred cancer: Prospect and challenges in Africa

: The completion of the human genome project and the accomplished milestones in the human proteome project; as well as the progress made so far in computational bioinformatics and “big data” processing have contributed immensely to individualized/personalized medicine in the developed world.At the dawn of precision medicine, various omics-based therapies and bioengineering can now be applied accurately for the diagnosis, prognosis, treatment, and risk stratifcation of cancer in a manner that was hitherto not thought possible. The widespread introduction of genomics and other omics-based approaches into the postgraduate training curriculum of diverse medical and dental specialties, including pathology has improved the profciency of practitioners in the use of novel molecular signatures in patient management. In addition, intricate details about disease disparity among diferent human populations are beginning to emerge. This would facilitate the use of tailor-made novel theranostic methods based on emerging molecular evidences

Increased extracellular free-water in adult male rats following in utero exposure to maternal immune activation

BACKGROUND: In previous work, we applied novel in vivo imaging methods to reveal that white matter pathology in patients with first-episode psychosis (FEP) is mainly characterized by excessive extracellular free-water, and to a lesser extent by cellular processes, such as demyelination. Here, we apply a back-translational approach to evaluate whether or not a rodent model of maternal immune activation (MIA) induces patterns of white matter pathology that we observed in patients with FEP. To this end, we examined free-water and tissue-specific white matter alterations in rats born to mothers exposed to the viral mimic polyriboinosinic-polyribocytidylic acid (Poly-I:C) in pregnancy, which is widely used to produce alterations relevant to schizophrenia and is characterized by a robust neuroinflammatory response. METHOD: Pregnant dams were injected on gestational day 15 with the viral mimic Poly-I:C (4 mg/kg) or saline. Diffusion-weighted magnetic resonance images were acquired from 17 male offspring (9 Poly-I:C and 8 saline) on postnatal day 90, after the emergence of brain structural and behavioral abnormalities. The free-water fraction (FW) and tissue-specific fractional anisotropy (FAT), as well as conventional fractional anisotropy (FA) were computed across voxels traversing a white matter skeleton. Voxel-wise and whole-brain averaged white matter were tested for significant microstructural alterations in immune-challenged, relative to saline-exposed offspring. RESULTS: Compared to saline-exposed offspring, those exposed to maternal Poly-I:C displayed increased extracellular FW averaged across voxels comprising a white matter skeleton (t(15) = 2.74; p = 0.01). Voxel-wise analysis ascribed these changes to white matter within the corpus callosum, external capsule and the striatum. In contrast, no significant between-group differences emerged for FAT or for conventional FA, measured across average and voxel-wise white matter. CONCLUSION: We identified excess FW across frontal white matter fibers of rats exposed to prenatal immune activation, analogous to our "bedside" observation in FEP patients. Findings from this initial experiment promote use of the MIA model to examine pathological pathways underlying FW alterations observed in patients with schizophrenia. Establishing these mechanisms has important implications for clinical studies, as free-water imaging reflects a feasible biomarker that has so far yielded consistent findings in the early stages of schizophrenia

How many papillae in conventional papillary carcinoma? A clinical evidence-based pathology study of 235 unifocal encapsulated papillary thyroid carcinomas, with emphasis on the diagnosis of noninvasive follicular thyroid neoplasm with papillary-like nuclear features

Background: The percentage of papillae is a crucial criterion in differentiating noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) from papillary thyroid carcinomas (PTCs) and in sub-classifying PTC into classic and follicular variant. Since the description of NIFTP, three studies have shown that the presence of any papillae may be associated with nodal metastasis, which led to modification of the NIFTP criterion from <1% papillae to no true papillae allowed. We aim at providing clinical evidence-based data on the impact that papillary growth has on nodal spread and tumor genotype in tumors previously diagnosed as encapsulated unifocal PTC. Methods: A meticulous histopathologic examination was performed on 235 cases previously diagnosed as unifocal encapsulated PTC (U-EPTC). One hundred of these cases were subjected to BRAFV600E and NRASQ61R immunohistochemistry. Results: In our cohort, 27 patients (12%) had lymph node metastasis (N1) at the time of initial resection. Overall, 89% of the tumors in the N1 group contained 6550% papillae, compared with 13% in the N0/Nx group. Nodal metastases were only present in tumors with 651% papillae. In noninvasive U-EPTC (n = 161), N1 disease was seen only in tumors with 6510% papillae. A higher percentage of papillae within the tumor also correlated with an increased frequency of BRAFV600E and decreased rate of NRASQ61R. None of the 26 NRAS-positive cases had nodal disease, including the invasive tumors. Among 216 patients with follow-up (median: 5.2 years), 3 patients (1.5%) had distant metastases, all detected at the initial presentation. All three tumors displayed 100% follicular growth, and capsular or vascular invasion. There was no locoregional recurrence in the entire cohort. Conclusion: In U-EPTC, there is a strong correlation between high percentage of papillary growth, presence of nodal metastasis, and BRAF+/RAS- genotype regardless of invasive status. Nodal metastases were not seen in tumors with <1% papillae irrespective of invasive status. These findings indicate that the initial criterion of <1% papillae is still valid for the diagnosis of NIFTP. Reinstituting this criterion will spare a carcinoma diagnosis and unnecessary therapy with its side effects on patients who have negligible clinical risk

Cyclic-AMP induction of gap junctional intercellular communication increases bystander effect in suicide gene therapy

1. The journal Cinical Cancer Research is the original source of the material.2. This article is hosted on a website external to the CBCRA Open Access Archive. Selecting “View/Open” below will launch the full-text article in another browser window

Radio-frequency ablation of hepatocellular carcinoma before liver transplantation: a histologic and 'TUNEL' study

Radio-frequency ablation (RFA) is an increasingly used treatment modality for hepatocellular carcinoma (HCC) in patients awaiting liver transplantation (OLTX). The current study evaluates the effectiveness of RFA in this setting based on evaluation of total cell death in explanted native livers. We evaluated 36 tumors from 35 patients with RFA-treated HCC who underwent OLTX at our center between 1998 and 2002. Native livers from OLTX were extensively sampled for histologic evaluation. For each HCC, an estimate ratio of necrotic tumor areas was calculated based on hematoxylin and eosin (H&E) sections. In tumors with 10% or more residual viable areas, Tdt-mediated UTP nick-end labeling (TUNEL) was further performed to assess apoptosis in the morphologically 'viable' areas. A final 'tumor cell death' (TCD) ratio was recalculated for each HCC to include areas of apoptosis identified by TUNEL. Based on H&E evaluation, 22/36 (61.1%) HCC revealed > or = 90% necrosis including 12/36 HCC (33.3%) showing no evidence of residual viable tumor. The overall median tumor necrosis was 79%. When TUNEL findings were added, 26/36 (72.2%) HCC revealed > or = 90% TCD including 14/36 HCC (38.8%) showing complete TCD (median TCD of 88.4%). None of our patients died of HCC while awaiting OLTX. Longer RFA-to-transplant time appears to be associated with a higher TCD rate (median of 154.5 days in patients with less than 90% TCD vs 326 days for patients with > or = 90% TCD; P = 0.019). There was no significant correlation between tumor grade or pre-RFA size of the tumors and TCD rate in RFA-treated HCC (P = 0.11). Extensive TCD (88.4% median) can be obtained using RFA for HCC in patients awaiting OLTX. Our TUNEL findings suggest that RFA-induced cell injury could be associated with apoptosis