2,332 research outputs found

    Planning and adaptation measures for urban slum communities in West Africa : stochastic rainfall modeling applied to domestic rainwater harvesting and climate change adaptation

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    Over half of the world’s population is living in urban settlements, and most urban growth is occurring in developing countries. These countries’ economies are often unable to accommodate these rural-urban immigrations, resulting in millions of people settling in insecure communities known as urban slums. Current efforts to prevent urban slums include UN-HABITAT strategies to upgrade slums and stimulate urban/regional development. Urban metabolism analysis, which studies material and energy flows/stocks through urban processes, help decision-makers better understand their urban system. Nine lessons from past urban metabolism studies are presented to assist in finding answers on how to best solve urban slum challenges. Worldwide, improved water access rates are lowest for Sub-Saharan Africa and these low rates have important implications on the health and economy of the region. Domestic rainwater harvesting (DRWH) is proposed as a potential mechanism for water supply enhancement, especially for the poor urban households in the region, which is essential for development planning and poverty alleviation initiatives. Several parsimonious stochastic rainfall models are developed and compared for application to DRWH assessment in West Africa. A first-order Markov occurrence model with a mixed exponential amount model is selected as the best option for unconditioned Markov models. However, there is no clear advantage in selecting Markov models over spelllength models for DRWH, with each model having distinct strengths and weaknesses. It is clear DRWH can be successfully used as a water enhancement mechanism in West Africa for significant portions of the year. Climate model output is used to determine climate change impacts to DRWH and to assess the technology as an adaptation measure to climate change. Several statistical downscaling methods are used to downscale multiple climate models to the local level. Climate change is expected to have little impact on DRWH reliability in West Africa by the mid-21st century, with only slight temporal shifts in rainfall. Developing communities in this region can invest with confidence in DRWH systems for drinking water enhancement. Study results also suggest that community improvements toward implementing DRWH systems should be focused on increasing water storage, due to storm size frequency changes

    Perfectionism and motivation in sport: The mediating role of mental toughness

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    An extensive body of research has investigated links between perfectionism and 2 motivation, yet the underlying mechanisms linking these psychological characteristics 3 have been underexplored. In this study, we used an integrative modelling approach to 4 examine associations between dimensions of perfectionism (i.e., personal standards 5 [PSP] and concerns over mistakes [CMP]), mental toughness (MT), and motivational 6 orientations (i.e., self- [SDM] and non-self-determined motivation [NSDM]). Based on a 7 sample of 318 male (n = 218) and female (n = 100) tennis players (Mage = 17.61, SD = 8 2.41), fit indices derived from structural equation modelling supported a partially 9 mediated model. Residual PSP associated positively with MT (β = .74) and SDM (β = 10 .40), and negatively with NSDM (β = -.22). Conversely, residual CMP associated 11 negatively with MT (β = .14) and SDM (β = -.19), and positively with NSDM (β = .73). 12 Mental toughness was positively associated with SDM (β = .28), but was unrelated to 13 NSDM (β = .07). The relationship between residual PSP and SDM was partially 14 mediated by MT (standardized indirect effect: 95% CI = .19, .46). The findings of this 15 study support research linking dimensions of perfectionism with motivational 16 orientations and offers preliminary evidence on the mediating role of MT in the 17 association between these psychological constructs. With emerging research 18 supporting the capacity to develop MT through targeted interventions, the findings are 19 discussed alongside salient implications

    Development of Low-Cost Micromanipulation Systems for Small Extraterrestrial Samples

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    The analysis of microscale to mm-scale astromaterials often involves the transfer of samples from storage or collection substrates to analytical substrates. These transfers are accomplished by hand (via tweezers or fine-tipped needles) or by utilizing micromanipulation instruments. Freehand manipulation of small particles is extremely challenging due to involuntary hand tremors on the order of 100m and due to the triboelectric charging induced by frequent contact between the manipulation tool and the support substrate. Months or years of practice may be required before an investigator develops the necessary experience to confidently transfer a 10-20m particle in this manner. Handling even mm-sized particles with fine-tipped tweezers can be challenging, due to the inability to precisely control the force with which grains are being held. Mechanical, hydraulic, and motorized/electrical micromanipulators enable the precise handling of microscale samples and are often utilized in laboratories where frequent small sample preparation is required. However, the price of such instruments (~ 10,000to10,000 to 100,000) makes them cost-prohibitive for some institutions. Graduate students or early-career scientists interested in conducting research on interplanetary dust particles, Itokawa particles returned by Hayabusa, or future samples returned by OSIRIS-REx or Hayabusa2 may experience difficulty in justifying the expense of a micromanipulator to their advisors or principle investigators. Johnson Space Centers Astromaterials Acquisition and Curation Office and the Lunar and Planetary Institute conduct annual training for early career scientists and for investigators that require experience with handling of small extraterrestrial samples. In support of this training, we have been developing low-cost mechanical alternatives to expensive micromanipulators that training participants can implement in their respective facilities

    Localization of Angiotensin Converting Enzyme in Rabbit Cornea and Its Role in Controlling Corneal Angiogenesis \u3cem\u3ein vivo\u3c/em\u3e

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    Purpose: The renin angiotensin system (RAS) has been shown to modulate vascular endothelial growth factor and angiogenesis. In this study we investigated (i) the existence of the RAS components angiotensin converting enzyme (ACE) and angiotensin II receptors (AT1 and AT2) in the rabbit cornea using in vitro and ex vivo models and (ii) the effect of enalapril, an ACE inhibitor, to inhibit angiogenesis in rabbit cornea in vivo. Methods: New Zealand White rabbits were used. Cultured corneal fibroblasts and corneal epithelial cells were used for RNA isolation and cDNA preparation using standard molecular biology techniques. PCR was performed to detect the presence of ACE, AT1, and AT2 gene expression. A corneal micropocket assay to implant a vascular endothelial growth factor (VEGF) pellet in the rabbit cornea was used to induce corneal angiogenesis. Rabbits of the control group received sterile water, and the treated group received 3 mg/kg enalapril intramuscularly once daily for 14 days starting from day 1 of pellet implantation. The clinical eye examination was performed by slit-lamp biomicroscopy. We monitored the level of corneal angiogenesis in live animals by stereomicroscopy at days 4, 9, and 14 after VEGF pellet implantation. Collagen type IV and lectin immunohistochemistry and fluorescent microscopy were used to measure corneal angiogenesis in tissue sections of control and enalapril-treated corneas of the rabbits. Image J software was used to quantify corneal angiogenesis in the rabbit eye in situ. Results: Our data demonstrated the presence of ACE, AT1, and AT2 expression in corneal fibroblasts. Cells of corneal epithelium expressed AT1 and AT2 but did not show ACE expression. Slit-lamp examination did not show any significant difference between the degree of edema or cellular infiltration between the corneas of control and enalapril-treated rabbits. VEGF pellet implantation caused corneal angiogenesis in the eyes of vehicle-treated control rabbits, and the mean area of corneal neovascularization was 1.8, 2.8, and 3.2 mm2 on days 4, 9, and 14, respectively. Enalapril treatment caused a notable decrease in corneal neovascularization of 44% (1 mm2), 28% (2.1 mm2), and 31% (2.2 mm2) on the three tested time points, respectively. The immunostaining of corneal tissue sections with collagen type IV and lectin confirmed the presence of blood vessels, with enalapril-treated rabbit corneas showing a lesser degree of blood vessel staining. Conclusions: Corneal cells show expression of tissue RAS components, such as ACE, AT1, and AT2. Treatment with ACE inhibitor enalapril markedly decreased corneal angiogenesis in a rabbit model of VEGF-induced corneal neovascularization, suggesting that ACE inhibitors may represent a novel therapeutic strategy to treat corneal angiogenesis

    Trichostatin A Inhibits Corneal Haze \u3cem\u3ein vitro\u3c/em\u3e and \u3cem\u3ein vivo\u3c/em\u3e

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    PURPOSE. Trichostatin A (TSA), a histone deacetylase inhibitor, has been shown to suppress TGF- –induced fibrogenesis in many nonocular tissues. The authors evaluated TSA cytotoxicity and its antifibrogenic activity on TGF- –driven fibrosis in the cornea with the use of in vitro and in vivo models. METHODS. Human corneal fibroblasts (HSFs) were used for in vitro studies, and New Zealand White rabbits were used for in vivo studies. Haze in the rabbit cornea was produced with photorefractive keratectomy (PRK) using excimer laser. Trypan blue exclusion and MTT assays evaluated TSA cytotoxicity to the cornea. Density of haze in the rabbit eye was graded with slit lamp biomicroscopy. Real-time PCR, immunoblotting, or immunocytochemistry was used to measure -smooth muscle actin (SMA), fibronectin, and collagen type IV mRNA or protein levels. TUNEL assay was used to detect cell death. RESULTS. TSA concentrations of 250 nM or less were noncytotoxic and did not alter normal HSF morphology or proliferation. TGF- 1 treatment of HSF significantly increased mRNA and protein levels of SMA (9-fold), fibronectin (2.5-fold), and collagen type IV (2-fold). TSA treatment showed 60% to 75% decreases in TGF- 1–induced SMA and fibronectin mRNA levels and 1.5- to 3.0-fold decreases in protein levels but had no effect on collagen type IV mRNA or protein levels in vitro. Two-minute topical treatment of TSA on rabbit corneas subjected to 9 D PRK significantly decreased corneal haze in vivo. CONCLUSIONS. TSA inhibits TGF- 1–induced accumulation of extracellular matrix and myofibroblast formation in the human cornea in vitro and markedly decreases haze in rabbit cornea in vivo

    Investigating Astromaterials Curation Applications for Dexterous Robotic Arms

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    The Astromaterials Acquisition and Curation office at NASA Johnson Space Center is currently investigating tools and methods that will enable the curation of future astromaterials collections. Size and temperature constraints for astromaterials to be collected by current and future proposed missions will require the development of new robotic sample and tool handling capabilities. NASA Curation has investigated the application of robot arms in the past, and robotic 3-axis micromanipulators are currently in use for small particle curation in the Stardust and Cosmic Dust laboratories. While 3-axis micromanipulators have been extremely successful for activities involving the transfer of isolated particles in the 5-20 micron range (e.g. from microscope slide to epoxy bullet tip, beryllium SEM disk), their limited ranges of motion and lack of yaw, pitch, and roll degrees of freedom restrict their utility in other applications. For instance, curators removing particles from cosmic dust collectors by hand often employ scooping and rotating motions to successfully free trapped particles from the silicone oil coatings. Similar scooping and rotating motions are also employed when isolating a specific particle of interest from an aliquot of crushed meteorite. While cosmic dust curators have been remarkably successful with these kinds of particle manipulations using handheld tools, operator fatigue limits the number of particles that can be removed during a given extraction session. The challenges for curation of small particles will be exacerbated by mission requirements that samples be processed in N2 sample cabinets (i.e. gloveboxes). We have been investigating the use of compact robot arms to facilitate sample handling within gloveboxes. Six-axis robot arms potentially have applications beyond small particle manipulation. For instance, future sample return missions may involve biologically sensitive astromaterials that can be easily compromised by physical interaction with a curator; other potential future returned samples may require cryogenic curation. Robot arms may be combined with high resolution cameras within a sample cabinet and controlled remotely by curator. Sophisticated robot arm and hand combination systems can be programmed to mimic the movements of a curator wearing a data glove; successful implementation of such a system may ultimately allow a curator to virtually operate in a nitrogen, cryogenic, or biologically sensitive environment with dexterity comparable to that of a curator physically handling samples in a glove box

    Meca500 Robotic Arm Developments Towards Astromaterials Curation Applications

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    As a part of the ongoing efforts to develop new curation tools and techniques for astromaterials within the Astromaterials Acquisition and Curation office at NASAs Johnson Space Center, we are developing a variety of manually and electrically controlled micromanipulation systems. Most current techniques require manual manipulation, and in some cases the manipulation task is being done entirely freehand. The motorized systems avail-able are restricted to three degrees of freedom and use proprietary control systems. For example, the MicroSupport AxisPro manipulation system currently used in microscale particle experiments is limited in its range of motion, as it can only move the manipulators in a three axis Cartesian range over a predetermined area above microscope slides. While having an efficient user interface, the control system is proprietary and prevents custom development and optimization to extend the viable applications of the system. In order to address some of these limitations, we have been testing robotic designs with multiple degrees of freedom and of a variety of designs. We are currently investigating the Meca500 robotic arm by Mecademic as a potential manipulation system to overcome some of these obstacles

    Some effects of ultrasonic radiation on normal tissues

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    Lesions can be produced in many different tissues with ultrasonic irradiation at intensities varying from 1 to 3 watts/sq cm for periods of 1 to 15 minutes. The higher the intensity and the longer the duration of treatment, the more severe were the lesions. Focused ultrasound waves of 37.5 total watts for 5 to 15 minutes produced localized areas of necrosis in liver.Other histologic lesions produced by various intensities and durations of treatment included necrosis, inflammation and edema of skin, subcutaneum, and muscle; degeneration, necrosis and giant cell reaction in testis; necrosis, ulcers, inflammation and hemorrhage in the intestines; and necrosis of bone and hyaline droplet change in renal tubular epithelium.Cavitation, probably due to the accumulation of bubbles of gas, was not observed in livers or other tissues of living animals that were treated. The change was produced in the livers of animals treated in situ after death and in livers removed from the body and treated.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32204/1/0000263.pd
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