Determination of trace amounts of Brown HT as a food dye by a CPE-scanometry method

AbstractIn this study, trace amounts of Brown HT were extracted, pre-concentrated and determined by cloud point extraction-scanometry (CPE-scanometry) as a simple, fast and inexpensive method. The procedure is based on CPE of Brown HT from an aqueous solution, diluting the extracted surfactant-rich phase with ethanol to 500μL, transferring the appropriate volume to Plexiglas® cells and scanning the cells. Then, the colour of each cell was analyzed by software written in visual basic (VB 6) into red, green and blue values. Effective parameters for the extraction efficiency, such as the pH of the system, the concentration of surfactant, the equilibration temperature and equilibration time, were investigated and optimized. Under optimal conditions, the calibration curve was linear in the range of 0.06–2.60mgL−1. The detection limit of the proposed method was 0.04mgL−1. In addition, the effects of some foreign species, including cations, anions and dyes, were investigated. The method was applied successfully for the determination of Brown HT in some water samples

Online Coding for Reliable Data Transfer in Lossy Wireless Sensor Networks

Abstract. Bulk transport underlies data exfiltration and code update facilities in WSNs, but existing approaches are not designed for highly lossy and variable-quality links. We observe that Maymounkov’s rateless online codes are asymptotically more efficient, but can perform poorly in the WSN operating region. We analyze and optimize coding parameters and present the design and evaluation of RTOC, a protocol for bulk transport that recovered over 95 % of application data despite up to 84% packet loss in a MicaZ network.

Network coding as a coloring problem (Invited paper)

We consider a multicast configuration with two sources, and translate the network code design problem to vertex coloring of an appropriately defined graph. This observation enables to derive code design algorithms and alphabet size bounds, as well as establish a connection with a number of well-known results from discrete mathematics that increase our insight in the different trade-offs possible for network coding

Long Distance Continuous-Variable Quantum Key Distribution with a Gaussian Modulation

We designed high-efficiency error correcting codes allowing to extract an errorless secret key in a continuous-variable quantum key distribution protocol using a Gaussian modulation of coherent states and a homodyne detection. These codes are available for a wide range of signal-to-noise ratios on an AWGN channel with a binary modulation and can be combined with a multidimensional reconciliation method proven secure against arbitrary collective attacks. This improved reconciliation procedure considerably extends the secure range of a continuous-variable quantum key distribution with a Gaussian modulation, giving a secret key rate of about 10^{-3} bit per pulse at a distance of 120 km for reasonable physical parameters.Comment: 8 pages, 5 figures, 5 table

Irregular behaviour of class numbers and Euler-Kronecker constants of cyclotomic fields: the log log log devil at play

Kummer (1851) and, many years later, Ihara (2005) both posed conjectures on invariants related to the cyclotomic field $\mathbb Q(\zeta_q)$ with $q$ a prime. Kummer's conjecture concerns the asymptotic behaviour of the first factor of the class number of $\mathbb Q(\zeta_q)$ and Ihara's the positivity of the Euler-Kronecker constant of $\mathbb Q(\zeta_q)$ (the ratio of the constant and the residue of the Laurent series of the Dedekind zeta function $\zeta_{\mathbb Q(\zeta_q)}(s)$ at $s=1$). If certain standard conjectures in analytic number theory hold true, then one can show that both conjectures are true for a set of primes of natural density 1, but false in general. Responsible for this are irregularities in the distribution of the primes. With this survey we hope to convince the reader that the apparently dissimilar mathematical objects studied by Kummer and Ihara actually display a very similar behaviour.Comment: 20 pages, 1 figure, survey, to appear in `Irregularities in the Distribution of Prime Numbers - Research Inspired by Maier's Matrix Method', Eds. J. Pintz and M. Th. Rassia

Photodynamic antimicrobial chemotherapy coupled with the use of the photosensitizers methylene blue and temoporfin as a potential novel treatment for Staphylococcus aureus in burn infections

Photodynamic antimicrobial chemotherapy (PACT) is a novel alternative antimicrobial therapy that elicits a broad mechanism of action and therefore has a low probability of generating resistance. Such properties make PACT ideally suited for utilization in localized applications such as burn wounds. The aim of this study was to determine the antimicrobial activity of MB and temoporfin against both a S. aureus isolate and a P. aeruginosa isolate in light (640 nm) and dark conditions at a range of time points (0–20 min). A Staphylococcus aureus isolate and a Pseudomonas aeruginosa isolate were treated in vitro with methylene blue (MB) and temoporfin under different conditions following exposure to light at 640 nm and in no-light (dark) conditions. Bacterial cell viability [colony-forming units (c.f.u.) ml−1] was then calculated. Against P. aeruginosa , when MB was used as the photosensitizer, no phototoxic effect was observed in either light or dark conditions. After treatment with temoporfin, a reduction of less than one log (7.00×107 c.f.u. ml−1) was observed in the light after 20 min of exposure. However, temoporfin completely eradicated S. aureus in both light and dark conditions after 1 min (where a seven log reduction in c.f.u. ml−1 was observed). Methylene blue resulted in a loss of S. aureus viability, with a two log reduction in bacterial viability (c.f.u. ml−1) reported in both light and dark conditions after 20 min exposure time. Temoporfin demonstrated greater antimicrobial efficacy than MB against both the S. aureus and P. aeruginosa isolates tested. At 12.5 µM temoporfin resulted in complete eradication of S. aureus . In light of this study, further research into the validity of PACT, coupled with the photosensitizers (such as temoporfin), should be conducted in order to potentially develop alternative antimicrobial treatment regimes for burn wounds.</jats:p

Statistical Mechanics Analysis of LDPC Coding in MIMO Gaussian Channels

Using analytical methods of statistical mechanics, we analyse the typical behaviour of a multiple-input multiple-output (MIMO) Gaussian channel with binary inputs under LDPC network coding and joint decoding. The saddle point equations for the replica symmetric solution are found in particular realizations of this channel, including a small and large number of transmitters and receivers. In particular, we examine the cases of a single transmitter, a single receiver and the symmetric and asymmetric interference channels. Both dynamical and thermodynamical transitions from the ferromagnetic solution of perfect decoding to a non-ferromagnetic solution are identified for the cases considered, marking the practical and theoretical limits of the system under the current coding scheme. Numerical results are provided, showing the typical level of improvement/deterioration achieved with respect to the single transmitter/receiver result, for the various cases.Comment: 25 pages, 7 figure

Shared and unique features of predator-associated morphological divergence in three livebearing fishes

Divergent natural selection (fitness trade-offs) between environments often drives intraspecific diversification. When multiple species face a common environmental gradient their patterns of divergence might exhibit both shared and unique elements. We investigated shared and unique elements of diversification for three species of livebearing fishes (Poeciliidae) across a predator gradient (piscivorous fish vs. no piscivorous fish). All species (Gambuia affinis from the United States, G. hubbsi from the Bahamas and P. reticulata from Trinidad) exhibited a posterior shift in body allocation and more elongate bodies in predator populations. This morphological shift applied not only across species, but across age/gender classes, particular predator species and gross habitat types. Each species also had unique features of divergence, which may reflect peculiarities unique to their natal environments. We hypothesize much of the predator-associated morphology enhances fitness in the presence of predators but decreases fitness in the absence of predators. Preliminary evidence supports this hypothesis. We additionally found gonopodium size divergence in both Gambusia species that was opposite a trend previously found in P. reticulata. Partitioning phenotypic variation for multiple species into shared and unique responses across environmental gradients is a useful tool for elucidating general and localized mechanisms of diversification. Divergent natural selection (DNS) is a powerful mechanism that generates and maintains phenotypic diversity (Rice and Hostert 1993; Orr and Smith 1998; Schluter 2000b). DNS is created by functional trade-offs between alternative environments (Robinson and Wilson 1994; Robinson et al. 1996; Schluter 2000b). Depending on how environments vary (e.g. fine- or coarse-grained variation; sensu Levins 1968), DNS can lead to evolution of either canalized genetic differences between populations or phenotypic plasticity (West-Eberhard 1989; Robinson and Wilson 1994; Orr and Smith 1998; Schluter 2000b). DNS results in population differentiation through either of these mechanisms. That is, populations may differ from each other because of fixed genetic differences or because each is similarly plastic but their current environments differ. Environmental differences that typically produce population divergence include predation, competition, or abiotic stresses (Magurran and May 1999; Schluter 2000b). Consider the case where the sign of selection on focal traits differs across environments. Consider also that several species are evolving adaptive solutions in these environments. Some elements of evolutionary response will be similar across species. For example, species A and B may largely respond in a similar manner. Yet other aspects of response to DNS will be speciesspecific (A responds one way; B responds differently). In theory, after accounting for gross differences between species, the unique and shared elements of response to DNS can be identified. This approach allows one to integrate the study of phenotypic variation across selective environments, populations and species. Empirical studies of diversification in vertebrates has focused on resource competition and niche partitioning (Robinson and Wilson 1994; Van Valkenburgh and Wayne 1994; Smith and Skulason 1996; Schluter 2000a). However, predation is among the most important factors structuring natural populations (Sih et al. 1985; Kerfoot and Sih 1987; Jackson et al. 2001). Predators should not only change the distribution and abundance of species (via lethal and behavioral impacts on prey), but should also produce diversification—changes in the distribution and abundance of phenotypes within species (Endler 1995; DeWitt et al. 2000; Trussell 2000; Van Buskirk and Schmidt 2000). Although predation is often thought responsible for the evolution of inducible defenses among invertebrates (Harvell 1986; Havel 1987; Tollrian and Harvell 1999), studies investigating the importance of predation in vertebrate diversification are less common. Most studies of vertebrate evolutionary responses to predation center on life history changes (e.g. Skelly and Werner 1990; Rodd and Reznick 1997; Belk 1998; Johnson and Belk 2001; Reznick et al. 2001). Investigation of morphological divergence between alternative predator environments in vertebrates is less common (Brönmark and Miner 1992; Van Buskirk et al. 1997; Walker 1997; Lardner 2000; Relyea 2001). In this study, we examined body shape divergence in three species of livebearing fishes across alternative predator regimes. Furthermore we evaluate trends within and between species to identify both unique and shared aspects of diversification among prey species

Ten-Year Analysis of Bacterial Colonisation and Outcomes of Major Burn Patients with a Focus on Pseudomonas aeruginosa

A retrospective descriptive study included patients admitted with severe burns over the course of 10 years (2008–2018). Across all patients, there were 39 different species of bacteria, with 23 species being Gram-negative and 16 being Gram-positive bacteria, with also five different species of fungi cultured. Pseudomonas aeruginosa was the most commonly isolated organism, with 57.45% of patients having a positive culture. There was a significant difference in the number of P. aeruginosa isolated from patients that acquired their burns at work, in a garden, inside a vehicle, in a garage or in a public place. In patients that were positive for P. aeruginosa, the number of operations was higher (2.4) and the length of stay was significantly increased (80.1 days). Patients that suffered from substance abuse demonstrated significantly higher numbers of isolated P. aeruginosa (14.8%). Patients that suffered from both mental health illness and substance abuse demonstrated significantly higher numbers of P. aeruginosa isolated (18.5%). In the P. aeruginosa-negative group, there were significantly fewer patients that had been involved in a clothing fire. Furthermore, in the P. aeruginosa-negative patient cohort, the mortality rate was significantly higher (p = 0.002). Since the incidence of P. aeruginosa was also associated with a decreased mortality rate, it may be that patients admitted to hospital for shorter periods of time were less likely to be colonised with P. aeruginosa. This study demonstrates novel factors that may increase the incidence of P. aeruginosa isolated from burn patients