Laser Generation of Narrow Band Ultrasound

Laser based sensor systems to replace conventional piezoelectric contact transducers for ultrasonic testing continue under development for applications where contact with the specimen surface is undesirable or impossible. To date, such systems are considerably less sensitive than their piezoelectric counterparts. As a result, a great deal of effort has contributed to the development of a number of interferoroetric transducer systems to detect ultrasound. Increasingly, however, researchers have begun looking at laser ultrasonic sources to see what improvements might be made to enhance overall system sensitivity for laser generation and detection of ultrasound

Activation of inflammatory responses in human U937 macrophages by particulate matter collected from dairy farms: an in vitro expression analysis of pro-inflammatory markers

Abstract Background The purpose of the present study was to investigate activation of inflammatory markers in human macrophages derived from the U937 cell line after exposure to particulate matter (PM) collected on dairy farms in California and to identify the most potent components of the PM. Methods PM from different dairies were collected and tested to induce an inflammatory response determined by the expression of various pro-inflammatory genes, such as Interleukin (IL)-8, in U937 derived macrophages. Gel shift and luciferase reporter assays were performed to examine the activation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and Toll-like-receptor 4 (TLR4). Results Macrophage exposure to PM derived from dairy farms significantly activated expression of pro-inflammatory genes, including IL-8, cyclooxygenase 2 and Tumor necrosis factor-alpha, which are hallmarks of inflammation. Acute phase proteins, such as serum amyloid A and IL-6, were also significantly upregulated in macrophages treated with PM from dairies. Coarse PM fractions demonstrated more pro-inflammatory activity on an equal-dose basis than fine PM. Urban PM collected from the same region as the dairy farms was associated with a lower concentration of endotoxin and produced significantly less IL-8 expression compared to PM collected on the dairy farms. Conclusion The present study provides evidence that the endotoxin components of the particles collected on dairies play a major role in mediating an inflammatory response through activation of TLR4 and NF-κB signaling

Individual differences in explicit and implicit visuomotor learning and working memory capacity

The theoretical basis for the association between high working memory capacity (WMC) and enhanced visuomotor adaptation is unknown. Visuomotor adaptation involves interplay between explicit and implicit systems. We examined whether the positive association between adaptation and WMC is specific to the explicit component of adaptation. Experiment 1 replicated the positive correlation between WMC and adaptation, but revealed this was specific to the explicit component of adaptation, and apparently driven by a sub-group of participants who did not show any explicit adaptation in the correct direction. A negative correlation was observed between WMC and implicit learning. Experiments 2 and 3 showed that when the task restricted the development of an explicit strategy, high WMC was no longer associated with enhanced adaptation. This work reveals that the benefit of high WMC is specifically linked to an individual’s capacity to use an explicit strategy. It also reveals an important contribution of individual differences in determining how adaptation is performed

Catalytic Supercritical Water Gasification of Refuse Derived Fuel for High Energy Content Fuel Gas

Refuse derived fuel (RDF) was processed using hydrothermal gasification at high temperature to obtain a high energy content fuel gas. Supercritical water gasification of RDF was conducted at a temperature of 500 °C and 29 MPa pressure and also in the presence of a solid RuO2/γ-Al2O3 catalyst. The effect of residence time (0, 30 and 60 min) and different ruthenium loadings (5, 10, 20 wt% RuO2/γ-Al2O3) were investigated. Up to 93 % carbon gasification efficiency was achieved in the presence of 20 wt% RuO2/γ-Al2O3 catalyst. The fuel gas with the highest energy value of 22.5 MJ Nm−3 was produced with the 5 wt% RuO2/γ-Al2O3 catalyst after 30 min reaction time. The results were compared with the use of NaOH as a homogeneous catalyst. When NaOH was used, the maximum gross calorific value of the product gas was 32.4 MJ Nm−3 at 60 min reaction time as a result of CO2 fixation. High yields of H2 and CH4 were obtained in the presence of both the NaOH and RuO2/γ-Al2O3 catalysts

Scallop swimming kinematics and muscle performance: modelling the effects of "within-animal" variation in temperature sensitivity

Escape behaviour was investigated in Queen scallops (Aequipecten opercularis) acclimated to 5, 10 or 15 degrees C and tested at their acclimation temperature. Scallops are active molluscs, able to escape from predators by jet-propelled swimming using a striated muscle working in opposition to an elastic hinge ligament. The first cycle of the escape response was recorded using high-speed video ( 250 Hz) and whole-animal velocity and acceleration determined. Muscle shortening velocity, force and power output were calculated using measurements of valve movement and jet area, and a simple biomechanical model. The average shortening speed of the adductor muscle had a Q(10) of 2.04, significantly reducing the duration of the jetting phase of the cycle with increased temperature. Muscle lengthening velocity and the overall duration of the clap cycle were changed little over the range 5 - 15 degrees C, as these parameters were controlled by the relatively temperature-insensitive, hinge ligament. Improvements in the average power output of the adductor muscle over the first clap cycle ( 222 vs. 139 W kg(-1) wet mass at 15 and 5 degrees C respectively) were not translated into proportional increases in overall swimming velocity, which was only 32% higher at 15 degrees C ( 0.37m s(-1)) than 5 degrees C (0.28 m s(-1))

A viscoelastic deadly fluid in carnivorous pitcher plants

Background : The carnivorous plants of the genus Nepenthes, widely distributed in the Asian tropics, rely mostly on nutrients derived from arthropods trapped in their pitcher-shaped leaves and digested by their enzymatic fluid. The genus exhibits a great diversity of prey and pitcher forms and its mechanism of trapping has long intrigued scientists. The slippery inner surfaces of the pitchers, which can be waxy or highly wettable, have so far been considered as the key trapping devices. However, the occurrence of species lacking such epidermal specializations but still effective at trapping insects suggests the possible implication of other mechanisms. Methodology/Principal Findings : Using a combination of insect bioassays, high-speed video and rheological measurements, we show that the digestive fluid of Nepenthes rafflesiana is highly viscoelastic and that this physical property is crucial for the retention of insects in its traps. Trapping efficiency is shown to remain strong even when the fluid is highly diluted by water, as long as the elastic relaxation time of the fluid is higher than the typical time scale of insect movements. Conclusions/Significance : This finding challenges the common classification of Nepenthes pitchers as simple passive traps and is of great adaptive significance for these tropical plants, which are often submitted to high rainfalls and variations in fluid concentration. The viscoelastic trap constitutes a cryptic but potentially widespread adaptation of Nepenthes species and could be a homologous trait shared through common ancestry with the sundew (Drosera) flypaper plants. Such large production of a highly viscoelastic biopolymer fluid in permanent pools is nevertheless unique in the plant kingdom and suggests novel applications for pest control

Mitochondrial simple sequenze repeats and 12s – rRNA gene reveal two distinct lineages of Crocidura russula (Mammalia, Sorcidae)

A short segment (135 bp) of the control region and a partial sequence (394 bp) of the 12S-rRNA gene in the mitochondrial DNA of Crocidura russula were analyzed in order to test a previous hypothesis regarding the presence of a gene flow disruption in northern Africa. This breakpoint would have separated northeast-African C. russula populations from the European (plus the northwest-African) populations. The analysis was carried out on specimens from Tunisia (C. r. cf agilis), Sardinia (C. r. ichnusae), and Pantelleria (C. r. cossyrensis), and on C. r. russula from Spain and Belgium. Two C. russula lineages were identified; they both shared R2 tandem repeated motifs of the same length (12 bp), but not the same primary structure. These simple sequence repeats were present in 12–23 copies in the right domain of the control region. Within the northeast-African populations, a polymorphism of repeat variants, not yet found in Europe, was recorded. A neighbor-join tree, which was built by sequences of the conserved 12S-rRNA gene, separated the two sister groups; it permitted us to date a divergence time of 0.5Myr. Our data discriminated two different mitochondrial lineages in accordance with the previous morphological and karyological data. Ecoclimatic barriers formed during the Middle Pleistocene broke the range of ancestral species in the Eastern Algeria (Kabile Mountains), leading to two genetically separate and modern lineages. The northeast-African lineage can today be located in Tunisia, Pantelleria, and Sardinia. The northwest- African lineage (Morocco and West Algeria), reaching Spain by anthropogenic introduction, spread over north Europe in modern times. The Palaearctic C. russula species is monophyletic, but a taxonomical revision (ie, to provide a full species rank for the northeast taxa and to put in synonymy some insular taxa) is required

Electric-field-induced coherent coupling of the exciton states in a single quantum dot

The signature of coherent coupling between two quantum states is an anticrossing in their energies as one is swept through the other. In single semiconductor quantum dots containing an electron-hole pair the eigenstates form a two-level system that can be used to demonstrate quantum effects in the solid state, but in all previous work these states were independent. Here we describe a technique to control the energetic splitting of these states using a vertical electric field, facilitating the observation of coherent coupling between them. Near the minimum splitting the eigenstates rotate in the plane of the sample, being orientated at 45{\deg} when the splitting is smallest. Using this system we show direct control over the exciton states in one quantum dot, leading to the generation of entangled photon pairs

Contribution to the understanding of tribological properties of graphite intercalation compounds with metal chloride

Intrinsic tribological properties of lamellar compounds are usually attributed to the presence of van der Waals gaps in their structure through which interlayer interactions are weak. The controlled variation of the distances and interactions between graphene layers by intercalation of electrophilic species in graphite is used in order to explore more deeply the friction reduction properties of low-dimensional compounds. Three graphite intercalation compounds with antimony pentachloride, iron trichloride and aluminium trichloride are studied. Their tribological properties are correlated to their structural parameters, and the interlayer interactions are deduced from ab initio bands structure calculations

Distinct Binding and Immunogenic Properties of the Gonococcal Homologue of Meningococcal Factor H Binding Protein

Neisseria meningitidis is a leading cause of sepsis and meningitis. The bacterium recruits factor H (fH), a negative regulator of the complement system, to its surface via fH binding protein (fHbp), providing a mechanism to avoid complement-mediated killing. fHbp is an important antigen that elicits protective immunity against the meningococcus and has been divided into three different variant groups, V1, V2 and V3, or families A and B. However, immunisation with fHbp V1 does not result in cross-protection against V2 and V3 and vice versa. Furthermore, high affinity binding of fH could impair immune responses against fHbp. Here, we investigate a homologue of fHbp in Neisseria gonorrhoeae, designated as Gonococcal homologue of fHbp (Ghfp) which we show is a promising vaccine candidate for N. meningitidis. We demonstrate that Gfhp is not expressed on the surface of the gonococcus and, despite its high level of identity with fHbp, does not bind fH. Substitution of only two amino acids in Ghfp is sufficient to confer fH binding, while the corresponding residues in V3 fHbp are essential for high affinity fH binding. Furthermore, immune responses against Ghfp recognise V1, V2 and V3 fHbps expressed by a range of clinical isolates, and have serum bactericidal activity against N. meningitidis expressing fHbps from all variant groups