MIMO Underwater Visible Light Communications: Comprehensive Channel Study, Performance Analysis, and Multiple-Symbol Detection

In this paper, we analytically study the bit error rate (BER) performance of underwater visible light communication (UVLC) systems with binary pulse position modulation (BPPM). We simulate the channel fading-free impulse response (FFIR) based on Monte Carlo numerical method to take into account the absorption and scattering effects. Additionally, to characterize turbulence effects, we multiply the aforementioned FFIR by a fading coefficient which for weak oceanic turbulence can be modeled as a lognormal random variable (RV). Moreover, to mitigate turbulence effects, we employ multiple transmitters and/or receivers, i.e., spatial diversity technique over UVLC links. Closed-form expressions for the system BER are provided, when equal gain combiner (EGC) is employed at the receiver side, thanks to Gauss-Hermite quadrature formula and approximation to the sum of lognormal RVs. We further apply saddle-point approximation, an accurate photon-counting-based method, to evaluate the system BER in the presence of shot noise. Both laser-based collimated and light emitting diode (LED)-based diffusive links are investigated. Since multiple-scattering effect of UVLC channels on the propagating photons causes considerable inter-symbol interference (ISI), especially for diffusive channels, we also obtain the optimum multiple-symbol detection (MSD) algorithm to significantly alleviate ISI effects and improve the system performance. Our numerical analysis indicates good matches between the analytical and photon-counting results implying the negligibility of signal-dependent shot noise, and also between analytical results and numerical simulations confirming the accuracy of our derived closed-form expressions for the system BER. Besides, our results show that spatial diversity significantly mitigates fading impairments while MSD considerably alleviates ISI deteriorations

Is inflammation a consequence of extracellular hyperosmolarity?

<p>Abstract</p> <p>Background</p> <p>There are several reports suggesting that hyperosmolarity induces inflammation. We recently showed that Dextran Sodium Sulfate causes inflammatory bowel disease due to hyperosmolarity. The aim of this study was to confirm the link between hyperosmolarity and inflammation by assessing osmolarity values in vivo during inflammation, compare the inflammatory potential of different osmotic agents and finally study the long-term consequences of hyperosmolarity on cell fate.</p> <p>Methods</p> <p>Osmotic pressures were measured in inflammatory liquids withdrawn from mice subjected to inflammation caused either by subcutaneous injection of Bacille Calmette-Guérin (BCG) or Freund adjuvant. Three epithelial cell lines (HT29, T24 and A549) were exposed up to 48 hours to increasing osmolarities (300, 600, 900 mOsm) of chemically inert molecules such as Mannitol, Propylene Glycol, and Glycerol and inflammatory response was assessed by Enzyme Linked ImmunoSorbent Assay (ELISA) and RNA Protection Assay (RPA). Finally, normal mouse macrophages were exposed to hyperosmotic conditions for long-term culture.</p> <p>Results</p> <p>The inflammation caused either by BCG or Freund adjuvant is correlated to hyperosmolarity in inflammatory liquids. The exposure of cells to the different compounds, whatever their molecular weight, has no effect on the secretion of cytokines as long as the osmolarity is below a threshold of 300 mOsm. Higher osmolarities result in the secretion of proinflammatory cytokines (Interleukin-8, Interleukin-6, Interleukin-1β and Tumor Necrosis factor-α). Long-term hyperosmotic culture extends normal macrophage half-life, from 44 days to 102 days, and alters the expression of p53, Bcl-2 and Bax.</p> <p>Conclusion</p> <p>The present study further suggests inflammation and hyperosmolarity are closely related phenomena if not synonymous.</p

Online Rotating PI Controller for NCS Over Communication Constraints

A new method for controlling the plant in networked control systems (NCSs) is proposed. Network time delay and packet loss are two major drawbacks in data communication networks which make NCSs unstable. Unlike previous related research works, this new proposed rotating PI controller based method has the advantage of considering time delay and packet loss effects simultaneously. Time delay is estimated online and then used for tuning the PI controller by rotating the phase plane, while packet loss sequences are modeled by Markov chain. This novel method improves the performance compared to other methods, especially when packets are dropped consecutively and network time delays are large. In fact, the results show that with the network time delay as large as 600 ms, and packet loss occurring evenly, the index of the rotating PI controller performance will be improved by approximately two and a half times compared to the performance index of classical Smith predictor. This ratio will be improved by approximately eight and a half times compared to the performance index of PI controller. Furthermore, in the case that the packet loss occurs consecutively, the results show a ratio improvement of approximately three and ten for our suggested method in comparison to Smith predictor and PI controller, respectively

Black-Box Uselessness: Composing Separations in Cryptography

Black-box separations have been successfully used to identify the limits of a powerful set of tools in cryptography, namely those of black-box reductions. They allow proving that a large set of techniques are not capable of basing one primitive ? on another ?. Such separations, however, do not say anything about the power of the combination of primitives ??,?? for constructing ?, even if ? cannot be based on ?? or ?? alone. By introducing and formalizing the notion of black-box uselessness, we develop a framework that allows us to make such conclusions. At an informal level, we call primitive ? black-box useless (BBU) for ? if ? cannot help constructing ? in a black-box way, even in the presence of another primitive ?. This is formalized by saying that ? is BBU for ? if for any auxiliary primitive ?, whenever there exists a black-box construction of ? from (?,?), then there must already also exist a black-box construction of ? from ? alone. We also formalize various other notions of black-box uselessness, and consider in particular the setting of efficient black-box constructions when the number of queries to ? is below a threshold. Impagliazzo and Rudich (STOC\u2789) initiated the study of black-box separations by separating key agreement from one-way functions. We prove a number of initial results in this direction, which indicate that one-way functions are perhaps also black-box useless for key agreement. In particular, we show that OWFs are black-box useless in any construction of key agreement in either of the following settings: (1) the key agreement has perfect correctness and one of the parties calls the OWF a constant number of times; (2) the key agreement consists of a single round of interaction (as in Merkle-type protocols). We conjecture that OWFs are indeed black-box useless for general key agreement. We also show that certain techniques for proving black-box separations can be lifted to the uselessness regime. In particular, we show that the lower bounds of Canetti, Kalai, and Paneth (TCC\u2715) as well as Garg, Mahmoody, and Mohammed (Crypto\u2717 & TCC\u2717) for assumptions behind indistinguishability obfuscation (IO) can be extended to derive black-box uselessness of a variety of primitives for obtaining (approximately correct) IO. These results follow the so-called "compiling out" technique, which we prove to imply black-box uselessness. Eventually, we study the complementary landscape of black-box uselessness, namely black-box helpfulness. We put forth the conjecture that one-way functions are black-box helpful for building collision-resistant hash functions. We define two natural relaxations of this conjecture, and prove that both of these conjectures are implied by a natural conjecture regarding random permutations equipped with a collision finder oracle, as defined by Simon (Eurocrypt\u2798). This conjecture may also be of interest in other contexts, such as amplification of hardness

Knowledge and Attitude Towards Epilepsy Among Biology Teachers in Fars Province, Iran

How to Cite this Article: Asadi-Pooya AA, Torabi-Nami M. Knowledge and Attitude Towards Epilepsy Among Biology Teachers in Fars Province, Iran. IranianJournal of Child Neurology 2012;6(1):13-18.ObjectiveThis study investigates the awareness and perception on “epilepsy” amongst biology teachers in Fars province, Iran.Materials &amp; MethodsA sample of high school biology teachers in Fars province, Iran, filled out an investigator designed questionnaire including questions about their knowledge and attitude concerning “epilepsy”. There were 17 questions in the questionnaire. Nine questions addressed the knowledge and the rest were about attitude and perception.ResultsForty two teachers completed the questionnaires. More than two-thirds of the participants had a fairly desirable awareness about the definition; whereas, only approximately 40% knew something about the etiology and treatment of epilepsy. More than two-thirds of the participants had a positive attitude towards epilepsy; however, misconceptions and negative attitudes were observed.ConclusionEducational programs for biology teachers and also other teachers are necessary to improve their knowledge, attitude and perception about epilepsy.References Sander JW, Shorvon SD. Incidence and prevalence studies in epilepsy and their methodological problems: a review. J Neurol Neurosurg Psychiatry 1987;50:829-39. Saraceno B. The WHO world health report 2001 on mental health. Epidemiol Psychiatr Soc 2002;11(2):83-7. Kim MK, Cho KH, Shin J, Kim SJ. A study of public attitudes towards epilepsy in Kwang-Juarea. J Kor Neurol Assoc 1994;12:410-27. DiIorio C, Shafer PO, Letz R, Henry T, Schomer DL, Yeager K, etal. The association of stigma with self-management and perception of health care among adults with epilepsy. Epilepsy Behav 2003;4(3):259-67. Aziz H, Akhtar SW, Hasan KZ. Epilepsy in Pakistan: stigma and psychological problems: a population-based epidemiologic study. Epilepsia 1997;38:1069-73. Ablon. The nature of stigma and medical conditions. Epilepsy Behav 2002;3:2-9. Jacoby A. Stigma, epilepsy and quality of life. Epilepsy Behav 2002;3:10-20. McLin WM, de Boer HM. Public perceptions about epilepsy. Epilepsia 1995;36:957-9. Daoud A, Al-Safi S, Otoom S, Wahba L, Alkofahi A. Public knowledge and attitudes towards epilepsy in Jordan. Seizure 2007;16:521-6. Ndour D, Diop AG, Ndiaye M, Niang C, Sarr MM, Ndiaye IP. A survey of school teachers’ knowledge and behaviour about epilepsy, in a developing country such as Senegal. [Article in French]. Aert Rev Neurol 2004;160(3):338-41. Millogo A, Siranyan AS. Knowledge of epilepsy and attitudes towards the condition among school-teachers in Bobo-Dioulasso (Burkina Faso). Epileptic Disord 2004;6(1):21-6. Masoudnia E. Awareness, understanding and attitudes towards epilepsy among Iranian ethnic groups. Seizure 2009;18(5):369-73. Fernandes PT, Noronha AL, Araújo U, Cabral P, Pataro R, de Boer HM, Prilipko L, Sander JW, Li LM. Teachers’ perception about epilepsy. Arq Neuropsiquiatr 2007;65(1):28-34. Aydin K, Yildiz H.Teacher’s perceptions in central turkey concerning epilepsy and asthma and short term effect of a brief education on the perception of epilepsy. Epilepsy Behav 2007;10:280-90. Caixeta J, Frenandes PT, Bell GS, Sander JW, Li LM. Epilepsy perception amongst university students. A survey. Arq Neuropsiquiatr 2007;65 (suppl 1):43-8

Research Paper: Effectiveness of Corticosteroid Therapy for Caustic Esophageal Injury

Background: Delayed caustic injury complications are common, especially in developing countries, and several treatments have been proposed to prevent the resulting esophageal strictures so far. Although inflammatory nature of caustic injury makes the anti-inflammatory agents a viable option, few studies have investigated these agents. High-dose corticosteroids therapy for reduction of stricture formation in the esophagus after the ingestion of caustic material is still a controversial topic. In this regard, this study aimed to determine the impact of high doses of methylprednisolone in preventing esophageal stricture.Methods: A total of 112 patients with grade II esophageal caustic injury, diagnosed by esophagogastroscopy within 24 hours of injury, were enrolled in our study. The treatment group (n=44) received methylprednisolone (1 g/d for 3 days), pantoprazole, ceftriaxone, and metronidazole and the control group (n=58) received the same regimen excluding methylprednisolone. Endoscopic and radiologic findings were used to compare the severity of the damage to the esophagus and stomach between the two groups.Results: After 8 months of follow-up, stricture development was observed in 3 (5.6%) patients in the treatment group and in 11 (19%) patients in the control group. The difference was statistically significant (P=0.038). The gastric outlet obstruction was observed in 4 (7.4%) patients in the treatment group and in 19 (32.7%) patients in the control group. Again, the difference was statistically significant (P&lt;0.05). There were not any side effects due to the high doses of methylprednisolone in the study group.Conclusion: High doses of methylprednisolone can prevent the development of esophageal stricture in grade II of caustic injury

Cloud-Aided Interference Management with Cache-Enabled Edge Nodes and Users

This paper considers a cloud-RAN architecture with cache-enabled multi-antenna Edge Nodes (ENs) that deliver content to cache-enabled end-users. The ENs are connected to a central server via limited-capacity fronthaul links, and, based on the information received from the central server and the cached contents, they transmit on the shared wireless medium to satisfy users' requests. By leveraging cooperative transmission as enabled by ENs' caches and fronthaul links, as well as multicasting opportunities provided by users' caches, a close-to-optimal caching and delivery scheme is proposed. As a result, the minimum Normalized Delivery Time (NDT), a high-SNR measure of delivery latency, is characterized to within a multiplicative constant gap of $3/2$ under the assumption of uncoded caching and fronthaul transmission, and of one-shot linear precoding. This result demonstrates the interplay among fronthaul links capacity, ENs' caches, and end-users' caches in minimizing the content delivery time.Comment: 9 pages, 3 figures, submitte

Geometric Spanners for Points Inside a Polygonal Domain

Let P be a set of n points inside a polygonal domain D. A polygonal domain with h holes (or obstacles) consists of h disjoint polygonal obstacles surrounded by a simple polygon which itself acts as an obstacle. We first study t-spanners for the set P with respect to the geodesic distance function d where for any two points p and q, d(p,q) is equal to the Euclidean length of the shortest path from p to q that avoids the obstacles interiors. For a case where the polygonal domain is a simple polygon (i.e., h=0), we construct a (sqrt(10)+eps)-spanner that has O(n log^2 n) edges where eps is the a given positive real number. For a case where there are h holes, our construction gives a (5+eps)-spanner with the size of O(sqrt(h) n log^2 n). Moreover, we study t-spanners for the visibility graph of P (VG(P), for short) with respect to a hole-free polygonal domain D. The graph VG(P) is not necessarily a complete graph or even connected. In this case, we propose an algorithm that constructs a (3+eps)-spanner of size almost O(n^{4/3}). In addition, we show that there is a set P of n points such that any (3-eps)-spanner of VG(P) must contain almost n^2 edges