Nest‐Site Limitation In Coffee Agroecosystems: Artificial Nests Maintain Diversity Of Arboreal Ants

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/116925/1/eap20051541478.pd

Real-time observation of epitaxial graphene domain reorientation.

Graphene films grown by vapour deposition tend to be polycrystalline due to the nucleation and growth of islands with different in-plane orientations. Here, using low-energy electron microscopy, we find that micron-sized graphene islands on Ir(111) rotate to a preferred orientation during thermal annealing. We observe three alignment mechanisms: the simultaneous growth of aligned domains and dissolution of rotated domains, that is, 'ripening'; domain boundary motion within islands; and continuous lattice rotation of entire domains. By measuring the relative growth velocity of domains during ripening, we estimate that the driving force for alignment is on the order of 0.1 meV per C atom and increases with rotation angle. A simple model of the orientation-dependent energy associated with the moiré corrugation of the graphene sheet due to local variations in the graphene-substrate interaction reproduces the results. This work suggests new strategies for improving the van der Waals epitaxy of 2D materials

Heat stress: A major contributor to poor animal welfare associated with long-haul live export voyages

Recent investigations by the Australian Department of Agriculture, Fisheries and Forestry into high mortalities on live export voyages from Australia to the Middle East during the Northern hemisphere summer suggest that animal welfare may be compromised by heat stress. The live export industry has generated a computer model that aims to assess the risk of heat stress and to contain mortality levels on live export ships below certain arbitrary limits. Although the model must be complied with under Australian law, it is not currently available for independent scientific scrutiny, and there is concern that model and the mandated space allowances are inadequate. This review appraises the relevant literature on heat stress in sheep and cattle, including laboratory studies aimed at mimicking the ambient temperatures and humidity levels likely to be encountered on live export voyages. Animal welfare is likely to be very poor as a result of heat stress in some shipments

Molecular Acoustic Angiography: A New Technique for High-resolution Superharmonic Ultrasound Molecular Imaging

Ultrasound molecular imaging utilizes targeted microbubbles to bind to vascular targets such as integrins, selectins, and other extracellular binding domains. After binding, these microbubbles are typically imaged using low pressures and multi-pulse imaging sequences. In this article, we present an alternative approach for molecular imaging using ultrasound which relies on superharmonic signals produced by microbubble contrast agents. Bound bubbles were insonified near resonance using a low frequency (4 MHz) and superharmonic echoes were received at high frequencies (25–30 MHz). While this approach was observed to produce declining image intensity during repeated imaging in both in vitro and in vivo experiments due to bubble destruction, the feasibility of superharmonic molecular imaging was demonstrated for transmit pressures which are sufficiently high to induce shell disruption in bound microbubbles. This approach was validated using microbubbles targeted to the αvβ3 integrin in a rat fibrosarcoma model (n=5), and combined with superharmonic images of free microbubbles to produce high contrast, high resolution 3D volumes of both microvascular anatomy and molecular targeting. Image intensity over repeated scans and the effect of microbubble diameter were also assessed in vivo, indicating that larger microbubbles yield increased persistence in image intensity. Using ultrasound-based acoustic angiography images rather than conventional B-mode ultrasound to provide the underlying anatomical information facilitates anatomical localization of molecular markers. Quantitative analysis of relationships between microvasculature and targeting information indicated that most targeting occurred within 50 µm of a resolvable vessel (>100 µm diameter). The combined information provided by these scans may present new opportunities for analyzing relationships between microvascular anatomy and vascular targets, subject only to limitations of the current mechanically-scanned system and microbubble persistence to repeated imaging at moderate mechanical indices

Nef functions in BLT mice to enhance HIV-1 replication and deplete CD4+CD8+ thymocytes

Background: The outcome of untreated HIV-1 infection is progression to AIDS and death in nearly all cases. Some important exceptions are the small number of patients infected with HIV-1 deleted for the accessory gene, nef. With these infections, disease progression is entirely suppressed or greatly delayed. Whether Nef is critical for high levels of replication or is directly cytotoxic remains controversial. The major problem in determining the role of Nef in HIV/AIDS has been the lack of tractable in vivo models where Nef’s complex pathogenic phenotype can be recapitulated. Results: Intravenous inoculation (3000 to 600,000 TCIU) of BLT humanized mice with HIV-1LAI reproducibly establishes a systemic infection. HIV-1LAI (LAI) replicates to high levels (peak viral load in blood 8,200,000 ± 1,800,000 copies of viral RNA/ml, range 3,600,000 to 20,400,000; n = 9) and exhaustively depletes CD4+ T cells in blood and tissues. CD4+CD8+ thymocytes were also efficiently depleted but CD4+CD8- thymocytes were partially resistant to cell killing by LAI. Infection with a nef-deleted LAI (LAINefdd) gave lower peak viral loads (1,220,000 ± 330,000, range 27,000 to 4,240,000; n = 17). For fourteen of seventeen LAINefdd-infected mice, there was little to no loss of either CD4+ T cells or thymocytes. Both LAIand LAINefdd-infected mice had about 8% of total peripheral blood CD8+ T cells that were CD38+HLA-DR+ compared \u3c1% for uninfected mice. Three exceptional LAINefdd-infected mice that lost CD4+ T cells received 600,000 TCIU. All three exhibited peak viral loads over 3,000,000 copies of LAINefdd RNA/ml. Over an extended time course, substantial systemic CD4+ T cell loss was observed for the three mice, but there was no loss of CD4+CD8+ or CD4+CD8- thymocytes. Conclusion: We conclude Nef is necessary for elevated viral replication and as a result indirectly contributes to CD4+ T cell killing. Further, Nef was not necessary for the activation of peripheral blood CD8+ T cells following infection. However, CD4+CD8+ thymocyte killing was dependent on Nef even in cases of elevated LAINefdd replication and T cell loss. This depletion of thymic T cell precursors may be a significant factor in the elevated pathogenicity of CXCR4 trophic HIV-1

Theory of ac electrokinetic behavior of spheroidal cell suspensions with an intrinsic dispersion

The dielectric dispersion, dielectrophoretic (DEP) and electrorotational (ER) spectra of spheroidal biological cell suspensions with an intrinsic dispersion in the constituent dielectric constants are investigated. By means of the spectral representation method, we express analytically the characteristic frequencies and dispersion strengths both for the effective dielectric constant and the Clausius-Mossotti factor (CMF). We identify four and six characteristic frequencies for the effective dielectric spectra and CMF respectively, all of them being dependent on the depolarization factor (or the cell shape). The analytical results allow us to examine the effects of the cell shape, the dispersion strength and the intrinsic frequency on the dielectric dispersion, DEP and ER spectra. Furthermore, we include the local-field effects due to the mutual interactions between cells in a dense suspension, and study the dependence of co-field or anti-field dispersion peaks on the volume fractions.Comment: accepted by Phys. Rev.

Can future physical assessment continue without support from computer science?

Purpose: Public health research requires data-intense studies over extended periods. With the advent of new technologies, there has been a resulting explosion in the amount of data generated by wearable sensors that can be used in physical activity research. Unfortunately the advances in hardware (e.g. device size), have not been matched by software to help manage, organise and analyse this data deluge. Public health research will require cross-disciplinary interactions with the computer science community in working towards solutions to automatically recognise human activities from wearable sensor data. Methods: We conducted a meta-review of contemporary computing science and information retrieval approaches such as: 1) the management and indexing of data from wearable accelerometer and image capturing devices; 2) the synchronisation and fusion of data from multiple devices (e.g. GPS, accelerometer, & SenseCam data); and 3) the representation of the meaning of image data Results: We identified: 1) Relational databases offer the most flexible solution for managing, indexing, and querying wearable sensor data information. 2) Advanced analysis of the signature of streams of data from separate devices may allow their data to be synchronised, but requires further advances. 3) The optimum method of pattern recognition in automatically annotating wearable image data is through the use of Support Vector Machine classifiers. Conclusions: Close interdisciplinary research between public health and computing science can help further our understanding of human activities. A first step may be the use of sensor web technologies to recognise a well-defined subset of activities that individuals are engaged in

Meta-heuristically seeded genetic algorithm for independent job scheduling in grid computing

Grid computing is an infrastructure which connects geographically distributed computers owned by various organizations allowing their resources, such as computational power and storage capabilities, to be shared, selected, and aggregated. Job scheduling problem is one of the most difficult tasks in grid computing systems. To solve this problem efficiently, new methods are required. In this paper, a seeded genetic algorithm is proposed which uses a meta-heuristic algorithm to generate its initial population. To evaluate the performance of the proposed method in terms of minimizing the makespan, the Expected Time to Compute (ETC) simulation model is used to carry out a number of experiments. The results show that the proposed algorithm performs better than other selected techniques

Early-life viral infection and allergen exposure interact to induce an asthmatic phenotype in mice

<p>Abstract</p> <p>Background</p> <p>Early-life respiratory viral infections, notably with respiratory syncytial virus (RSV), increase the risk of subsequent development of childhood asthma. The purpose of this study was to assess whether early-life infection with a species-specific model of RSV and subsequent allergen exposure predisposed to the development of features of asthma.</p> <p>Methods</p> <p>We employed a unique combination of animal models in which BALB/c mice were neonatally infected with pneumonia virus of mice (PVM, which replicates severe RSV disease in human infants) and following recovery, were intranasally sensitised with ovalbumin. Animals received low-level challenge with aerosolised antigen for 4 weeks to elicit changes of chronic asthma, followed by a single moderate-level challenge to induce an exacerbation of inflammation. We then assessed airway inflammation, epithelial changes characteristic of remodelling, airway hyperresponsiveness (AHR) and host immunological responses.</p> <p>Results</p> <p>Allergic airway inflammation, including recruitment of eosinophils, was prominent only in animals that had recovered from neonatal infection with PVM and then been sensitised and chronically challenged with antigen. Furthermore, only these mice exhibited an augmented Th2-biased immune response, including elevated serum levels of anti-ovalbumin IgE and IgG₁as well as increased relative expression of Th2-associated cytokines IL-4, IL-5 and IL-13. By comparison, development of AHR and mucous cell change were associated with recovery from PVM infection, regardless of subsequent allergen challenge. Increased expression of IL-25, which could contribute to induction of a Th2 response, was demonstrable in the lung following PVM infection. Signalling via the IL-4 receptor α chain was crucial to the development of allergic inflammation, mucous cell change and AHR, because all of these were absent in receptor-deficient mice. In contrast, changes of remodelling were evident in mice that received chronic allergen challenge, regardless of neonatal PVM infection, and were not dependent on signalling via the IL-4 receptor.</p> <p>Conclusion</p> <p>In this mouse model, interaction between early-life viral infection and allergen sensitisation/challenge is essential for development of the characteristic features of childhood asthma, including allergic inflammation and a Th2-biased immune response.</p