465 research outputs found
Recognition of Social Identity in Ants
Recognizing the identity of others, from the individual to the group level, is a hallmark of society. Ants, and other social insects, have evolved advanced societies characterized by efficient social recognition systems. Colony identity is mediated by colony specific signature mixtures, a blend of hydrocarbons present on the cuticle of every individual (the âlabelâ). Recognition occurs when an ant encounters another individual, and compares the label it perceives to an internal representation of its own colony odor (the âtemplateâ). A mismatch between label and template leads to rejection of the encountered individual. Although advances have been made in our understanding of how the label is produced and acquired, contradictory evidence exists about information processing of recognition cues. Here, we review the literature on template acquisition in ants and address how and when the template is formed, where in the nervous system it is localized, and the possible role of learning. We combine seemingly contradictory evidence in to a novel, parsimonious theory for the information processing of nestmate recognition cues
Dinomyrmex gigas (Latreille, 1802): a potential icon for Taman Negara Johor Endau Rompin
Dinomyrmex gigas (Latreille, 1802) is one of the largest ants in the world and the
largest in Southeast Asia. It is also more commonly known as the giant forest ant. This large
charismatic ant can be found in the forests of Southeast Asia, however it is not often sighted by
the public due to its predominant nocturnal nature. Despite being considerably well studied
compared to its smaller counterparts, most people know little about the giant forest ant beyond
its large size. Most studies on this species focus on the populations found in Malaysia and Brunei
characterizing many aspects of the natural history and biology of this species including its
foraging behaviour, diet, territoriality, reproduction and colony structure. While much is known
about the biology of this species, fragmented forest habitats may have an impact on the viability
and behaviour of this majestic giant ant of the forest. This study involved insectsâ viability
observation and sampling of ant specimens. The results of observations showed that D. gigas is
viable in Endau Rompin Johor National Park (TNJER). Then, various ecological aspects of D.
gigas was investigated through field studies and secondary information. Due to its size and
uniqueness this species has a potential to be developed into a nature tourism product for
Malaysia. The present study elaborated to further discover its daily activity, nesting and defence
behaviour which could be useful in developing it into a nature tourism product. As the species is
also limited in distribution to undisturbed forest, the issue of its survival is discussed with relation
to conservation of the tropical rainforest
Type I/II interferon in HIV-1-infected patients: expression in gut mucosa and in peripheral blood mononuclear cells and its modification upon probiotic supplementation
Expression of type I and II interferon (IFN) was evaluated in gut-associated lymphoid tissue (GALT) and peripheral blood mononuclear cells (PBMCs) of HIV-1-positive patients on long-term, suppressive, antiretroviral therapy before and after probiotic supplementation. IFNα subtypes and IFNÎČ were expressed at higher levels in GALT compared to PBMC, whereas an opposite trend of expression was recorded for IFNÎł. An increase of IFNα6, IFNα10, IFNα14, IFNα17, and IFNα21 and a decrease of IFNÎł were observed in both anatomical sites after probiotic supplementation
Right to Occupational Safety: Prevalence of Latent Tuberculosis Infection in Healthcare Workers. A 1-Year Retrospective Survey Carried out at Hospital of Lecce (Italy)
Prevention of latent tuberculosis infection (LTBI) in healthcare workers (HCWs) to ensure the âRight to Occupational Safetyâ is a special challenge globally, as HCWs have a higher risk of acquiring the infection in hospital settings because of frequent close exposure to patients suffering from tuberculosis (TB). Methods: Aretrospective study was performed with the aim of assessing the prevalence of LTBI related to demographical and occupational risk factors among HCWs employed in a large hospital in Italy. The study involved 1461 HCWs screened for LTBI by Mantoux tuberculin skin test (TST) and then confirmed with Interferon Gamma Release Assay (IGRA) test in case of positivity. Immunosuppressed and BGC-vaccinated workers were tested directly with IGRA. Results: LTBI was diagnosed in 4.1% of the HCWs and the prevalence resulted lower than other studies conducted in low TB incidence countries. The variables significantly linked with higher frequency of the infection were: age â„40 years (OR = 3.14; 95% CI: 1.13â8.74; p < 0.05), length of service â„15 years (OR = 4.11; 95% CI: 1.48â11.43; p < 0.05) and not being trained on TB prevention (OR = 3.46; 95% CI: 1.85â6.46; p < 0.05). Not trained HCWs presented a higher risk of LTBI also after adjustment for age and length of service, compared to trained HCWs. Conclusions: screening of HCWs for LTBI should be always considered in routinely occupational surveillance in order to early diagnose the infection and prevent its progression. Safety policies in hospital settings centered on workersâ training on TB prevention is crucial to minimize LTBI occurrence in HCWs
Crozierâs paradox revisited: maintenance of genetic recognition systems by disassortative mating
BackgroundOrganisms are predicted to behave more favourably towards relatives, and kin-biased cooperation has been found in all domains of life from bacteria to vertebrates. Cooperation based on genetic recognition cues is paradoxical because it disproportionately benefits individuals with common phenotypes, which should erode the required cue polymorphism. Theoretical models suggest that many recognition loci likely have some secondary function that is subject to diversifying selection, keeping them variable.ResultsHere, we use individual-based simulations to investigate the hypothesis that the dual use of recognition cues to facilitate social behaviour and disassortative mating (e.g. for inbreeding avoidance) can maintain cue diversity over evolutionary time. Our model shows that when organisms mate disassortatively with respect to their recognition cues, cooperation and recognition locus diversity can persist at high values, especially when outcrossed matings produce more surviving offspring. Mating system affects cue diversity via at least four distinct mechanisms, and its effects interact with other parameters such as population structure. Also, the attrition of cue diversity is less rapid when cooperation does not require an exact cue match. Using a literature review, we show that there is abundant empirical evidence that heritable recognition cues are simultaneously used in social and sexual behaviour.ConclusionsOur models show that mate choice is one possible resolution of the paradox of genetic kin recognition, and the literature review suggests that genetic recognition cues simultaneously inform assortative cooperation and disassortative mating in a large range of taxa. However, direct evidence is scant and there is substantial scope for future work
Unexpected increase of myocardial extracellular volume fraction in low cardiovascular risk HIV patients
Background
People living with HIV (PLWH) are prone to develop sub-clinical Cardiovascular (CV) disease, despite the effectiveness of combined Antiretroviral Therapy (cART). Algorithms developed to predict CV risk in the general population could be inaccurate when applied to PLWH. Myocardial Extra-Cellular Matrix (ECM) expansion, measured by computed tomography, has been associated with an increased CV vulnerability in HIV-negative population. Measurement of Myocardial Extra-Cellular Volume (ECV) by computed tomography or magnetic resonance, is considered a useful surrogate for clinical evaluation of ECM expansion. In the present study, we aimed to determine the extent of cardiovascular involvement in asymptomatic HIV-infected patients with the use of a comprehensive cardiac computed tomography (CCT) approach.
Materials and methods
In the present study, ECV in low atherosclerotic CV risk PLWH was compared with ECV of age and gender matched HIV- individuals. 53 asymptomatic HIVâ+âindividuals (45 males, age 48 (42.5â48) years) on effective cART (CD4â+âcell count: 450 cells/”L (IQR: 328â750); plasma HIV RNA: <37 copies/ml in all subjects) and 18 age and gender matched controls (14 males, age 55 (44.5â56) years) were retrospectively enrolled. All participants underwent CCT protocol to obtain native and postcontrast Hounsfield unit values of blood and myocardium, ECM was calculated accordingly.
Results
The ECV was significantly higher in HIVâ+âpatients than in the control group (ECV: 31% (IQR: 28%-31%) vs. 27.4% (IQR: 25%-28%), pâ<â0.001). The duration of cART (standardized ÎČâ=â0.56 (0.33â0.95), pâ=â0.014) and the years of exposure to HIV infection (standardized ÎČâ=â0.53 (0.4â0.92), pâ<â0.001), were positively and strongly associated with ECV values. Differences in ECV (pâ<â0.001) were also observed regarding the duration of cART exposure (<â5 years, 5â10 years and >â10 years). Moreover, ECV was independently associated with age of participants (standardized ÎČâ=â0.42 (0.33â0.89), pâ=â0.084).
Conclusions
HIV infection and exposure to antiretrovirals play a detrimental role on ECV expansion. An increase in ECV indicates ECM expansion, which has been associated to a higher CV risk in the general population. The non-invasive evaluation of ECM trough ECV could represent an important tool to further understand the relationship between HIV infection, cardiac pathophysiology and the increased CV risk observed in PLWH
LOW DROSS GENERATION WITH OXY-FUEL SYSTEM
Yield increase in aluminum melting operation is the most challenging goal to achieve. It has been proven that conventional oxy-fuel system can promote significant productivity increase and reduction in specific energy consumption. However, dross formation has been always a concern not only with oxy-fuel burner but also with airfuel burners. Praxair developed two new generation oxy-fuel burners for the aluminum industry, the Circular Motion Flame Burner and the Variable Oxidant Burner. The burners developed each one for specific furnace method of operation achieved reduction in dross formation by more than 25%, reduction in specific fuel consumption by up to 50%, 30% higher specific melt rate compared to traditional oxy-fuel process, increase in specific melt rate by a factor of two, and quality improvement. The Circular Motion Flame Burner, suitable for short heat cycles and continuous furnaces, promotes a nonstationary flame and very uniform heat transfer pattern to the process. The Variable Oxidant Burner suitable for short melting cycles and long holding cycles can be operated at the minimized fuel consumption by varying the oxygen concentration in the oxidant according to the phase throughout the heat cycle. Both burners designed for deep staging promote low peak flame temperature and consequently ultra low NOx emission rate
Measurement of the cosmic ray hadron spectrum up to 30 TeV at mountain altitude: the primary proton spectrum
The flux of cosmic ray hadrons at the atmospheric depth of 820 g/cm^2 has
been measured by means of the EAS-TOP hadron calorimeter (Campo Imperatore,
National Gran Sasso Laboratories, 2005 m a.s.l.). The hadron spectrum is well
described by a single power law : S(E_h) = (2.25 +- 0.21 +- 0.34(sys))
10^(-7)(E_h/1000)^(-2.79 +- 0.05) m^(-2) s^(-1) sr^(-1) GeV^(-1) over the
energy range 30 GeV-30 TeV. The procedure and the accuracy of the measurement
are discussed. The primary proton spectrum is derived from the data by using
the CORSIKA/QGSJET code to compute the local hadron flux as a function of the
primary proton spectrum and to calculate and subtract the heavy nuclei
contribution (basing on direct measurements). Over a wide energy range E_0 =
0.5-50 TeV its best fit is given by a single power law : S(E_0) = (9.8 +- 1.1
+- 1.6(sys)) 10^(-5) (E_0/1000)^(-2.80 +- 0.06) m^(-2) s^(-1) sr^(-1) GeV^(-1).
The validity of the CORSIKA/QGSJET code for such application has been checked
using the EAS-TOP and KASCADE experimental data by reproducing the ratio of the
measured hadron fluxes at the two experimental depths (820 and 1030 g/cm^2
respectively) at better than 10% in the considered energy range.Comment: 16 pages, 9 figures, accepted for publication in Astroparticle
Physic
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