1,043 research outputs found

    Mission Control Center - Houston

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    The Mission Control Center - Houston (MCC-H) was designed to control all NASA manned space flights from the first Gemini rendezvous through the Apollo program. The MCC-H is a three-story building which contains 112,000 square feet, and which required 30 months to implement. It has a capability to control a live mission and a simulation simultaneously, or two simulations simultaneously. This capability was provided by locating duplicate operational areas on separate floors. The facility layout is shown in Figures 1, 2, and 3. The MCC-H is comprised of five basic systems: the Display/Control System, the Real Time Computer Complex (RTCC), the Communications System, the Command System, and the Simulation, Checkout, and Training System (SCATS). These systems are designed to provide the flight operations team with the necessary real-time data and associated reference data for rapid assessment of mission progress, and for rapid decisions in the event of abnormal or emergency situations. The reference data are the result of the enormous effort that is spent prior to the mission in analyzing every possible contingency situation that may occur, and contains predicted trend data, mission rules and carefully planned, detailed operational procedures for regulating the mission

    Tentacle probes: eliminating false positives without sacrificing sensitivity

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    The majority of efforts to increase specificity or sensitivity in biosensors result in trade-offs with little to no gain in overall accuracy. This is because a biosensor cannot be more accurate than the affinity interaction it is based on. Accordingly, we have developed a new class of reagents based on mathematical principles of cooperativity to enhance the accuracy of the affinity interaction. Tentacle probes (TPs) have a hairpin structure similar to molecular beacons (MBs) for enhanced specificity, but are modified by the addition of a capture probe for increased kinetics and affinity. They produce kinetic rate constants up to 200-fold faster than MB with corresponding stem strengths. Concentration-independent specificity was observed with no false positives at up to 1 mM concentrations of variant analyte. In contrast, MBs were concentration dependent and experienced false positives above 3.88 μM of variant analyte. The fast kinetics of this label-free reagent may prove important for extraction efficiency, hence sensitivity and detection time, in microfluidic assays. The concentration-independent specificity of TPs may prove extremely useful in assays where starting concentrations and purities are unknown as would be the case in bioterror or clinical point of care diagnostics

    Density-functional study of Cu atoms, monolayers, and coadsorbates on polar ZnO surfaces

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    The structure and electronic properties of single Cu atoms, copper monolayers and thin copper films on the polar oxygen and zinc terminated surfaces of ZnO are studied using periodic density-functional calculations. We find that the binding energy of Cu atoms sensitively depends on how charge neutrality of the polar surfaces is achieved. Bonding is very strong if the surfaces are stabilized by an electronic mechanism which leads to partially filled surface bands. As soon as the surface bands are filled (either by partial Cu coverage, by coadsorbates, or by the formation of defects), the binding energy decreases significantly. In this case, values very similar to those found for nonpolar surfaces and for copper on finite ZnO clusters are obtained. Possible implications of these observations concerning the growth mode of copper on polar ZnO surfaces and their importance in catalysis are discussed.Comment: 6 pages with 2 postscript figures embedded. Uses REVTEX and epsf macro

    Conflict resolution in six United Methodist colleges in North Carolina : a plan

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    This study was undertaken to explore conflict and conflict resolution in organizations in general, and United Methodist institutions of higher education in North Carolina in particular. Further, the study was an effort to develop a useful plan for conflict resolution for these institutions. The basic research method used was the survey of literature, with attention to the literature of organizational conflict and conflict resolution, the literature of private institutions of higher education in North Carolina, and the literature of existing, and proven effective, experiences used in conflict resolution

    Inelastic neutron scattering studies of methyl chloride synthesis over alumina

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    Not only is alumina the most widely used catalyst support material in the world, it is also an important catalyst in its own right. One major chemical process that uses alumina in this respect is the industrial production of methyl chloride. This is a large scale process (650 000 metric tons in 2010 in the United States), and a key feedstock in the production of silicones that are widely used as household sealants. In this Account, we show how, in partnership with conventional spectroscopic and reaction testing methods, inelastic neutron scattering (INS) spectroscopy can provide additional insight into the active sites present on the catalyst, as well as the intermediates present on the catalyst surface.<p></p> INS spectroscopy is a form of vibrational spectroscopy, where the spectral features are dominated by modes involving hydrogen. Because of this, most materials including alumina are largely transparent to neutrons. Advantageously, in this technique, the entire “mid-infrared”, 0–4000 cm<sup>–1</sup>, range is accessible; there is no cut-off at 1400 cm<sup>–1</sup> as in infrared spectroscopy. It is also straightforward to distinguish fundamental modes from overtones and combinations. <p></p> A key parameter in the catalyst’s activity is the surface acidity. In infrared spectroscopy of adsorbed pyridine, the shifts in the ring stretching modes are dependent on the strength of the acid site. However, there is a very limited spectral range available. We discuss how we can observe the low energy ring deformation modes of adsorbed pyridine by INS spectroscopy. These modes can undergo shifts that are as large as those seen with infrared inspectroscopy, potentially enabling finer discrimination between acid sites. <p></p> Surface hydroxyls play a key role in alumina catalysis, but in infrared spectroscopy, the presence of electrical anharmonicity complicates the interpretation of the O–H stretch region. In addition, the deformations lie below the infrared cut-off. Both of these limitations are irrelevant to INS spectroscopy, and all the modes are readily observable. When we add HCl to the catalyst surface, the acid causes changes in the spectra. We can then deduce both that the surface chlorination leads to enhanced Lewis acidity and that the hydroxyl group must be threefold coordinated. <p></p> When we react η-alumina with methanol, the catalyst forms a chemisorbed methoxy species. Infrared spectroscopy clearly shows its presence but also indicates the possible coexistence of a second species. Because of INS spectroscopy’s ability to discriminate between fundamental modes and combinations, we were able to unambiguously show that there is a single intermediate present on the surface of the active catalyst. This work represents a clear example where an understanding of the chemistry at the molecular level can help rationalize improvements in a large scale industrial process with both financial and environmental benefits. <p></p&gt

    Project proposal on funding for parks

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    This study will look at state and county level parks and see what and if there are alternative funding solutions for these parks. We will interview officials and administrators of two parks, while using surveys to gather information about visitors of the parks. The interviews that we will use for the park officials and administrators will be semi-structured. When it comes to analyzing the data we receive from the interviews, we will use three techniques: member checking, qualitative coding, and developing themes. The second method we plan on using is surveys of park visitors. We want to conduct exit surveys with visitors of two different parks, one local and one state. Approximately 200 surveys will be collected from those visiting Table Rock State Park and Nettles Park in Clemson. This will give us a good summary of what people would like and not like. From these results we would be able to make inferences about the population of park visitors, and would we be able to advise parks which funding alternatives would be successful and unsuccessful

    Tentacle probe sandwich assay in porous polymer monolith improves specificity, sensitivity and kinetics

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    Nucleic acid sandwich assays improve low-density array analysis through the addition of a capture probe and a specific label, increasing specificity and sensitivity. Here, we employ photo-initiated porous polymer monolith (PPM) as a high-surface area substrate for sandwich assay analysis. PPMs are shown to enhance extraction efficiency by 20-fold from 2 μl of sample. We further compare the performance of labeled linear probes, quantum dot labeled probes, molecular beacons (MBs) and tentacle probes (TPs). Each probe technology was compared and contrasted with traditional hybridization methods using labeled sample. All probes demonstrated similar sensitivity and greater specificity than traditional hybridization techniques. MBs and TPs were able to bypass a wash step due to their ‘on–off’ signaling mechanism. TPs demonstrated reaction kinetics 37.6 times faster than MBs, resulting in the fastest assay time of 5 min. Our data further indicate TPs had the most sensitive detection limit (<1 nM) as well as the highest specificity (>1 × 104 improvement) among all tested probes in these experiments. By matching the enhanced extraction efficiencies of PPM with the selectivity of TPs, we have created a format for improved sandwich assays

    The contribution of condensation-corrosion in the morphological evolution of caves in semi-arid regions: preliminary investigations in the Kyrenia Range, Cyprus

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    The condensation-corrosion process occurs when airflow cools at the contact with colder cave walls. Condensed water becomes aggressive for soluble rocks and corrodes the walls. This process is particularly active close to cave entrances in high thermal gradient zones where external air enters caves. Condensation appears to be important where bat colonies are also present. Bat metabolism and guano decomposition release heat, vapour, and acids. Hence, bat colonies contribute to the increase of condensation- corrosion, especially by providing permanent moisture and chemical aggressiveness. Corrosive air convections produce rounded morphologies, such as ceiling channels, cupolas, and corroded older flowstones. This process has been overlooked in previous research, since related morphologies were often confused with those produced by early phreatic flow. Kyrenia Range in Cyprus has a semi-arid climate. All the studied caves developed along open-fractures. They are located both in recrystallized carbonates (limestone and dolostone, such as Smoky and Pigeons Caves), or in gypsum (First Day and Angry Bat Caves). We also studied a maze cave that acted as a spring in gypsum that initially developed under phreatic conditions, followed by an epiphreatic phase that allowed the development of notches (Fig Tree Cave, also named İncirli Show Cave). Due to the semi-arid climate, external air is very dry in summer, thus condensation seems to occur mainly in winter, when cave atmosphere instability allows large air exchanges between caves and surface atmosphere. In summer, evaporation prevails, allowing the development of popcorn lines in carbonate caves and massive gypsum crusts, stalagmites, and sidewalk rims in gypsum caves. However, the presence of a bat colony in a semi-confined chamber in Smoky Cave is probably the origin of the permanent moisture, also during the dry season, leading to a strong development of condensation-corrosion features such as ceiling cupolas, and possibly to the permanent activity of flowstones. In addition, we detected high concentrations of sulphur dioxide (SO2) and radon (Rn) in Fig Tree Cave, possibly related to the activity of the neighbouring overthrust. Based on the five studied caves in the Kyrenia Range and surroundings, the open-fracture caves in carbonates and gypsum have not undergone the typical initial phreatic stage, but have formed in a short time during Pleistocene as a result of the fast uplift of the range and were later reshaped by condensation-corrosion morphologies. Some gypsum caves may have formed entirely by this latter process, after initial minor fracture development. Cyprus is an outstanding area for studying the condensation-corrosion in caves, since a phreatic origin can be ruled out for most of the rounded morphologies. Prispevek kondenzacijske korozije pri razvoju jam v polsuhih območjih: predhodni rezultati v jamah Kirenijskega gorovja, CiperKondenzacijska korozija se pojavi ob stiku vlažnega zračnega toka s hladnimi jamskimi stenami. Pri tem na jamsko steno iz zraka kondenzira film vode, ki kemično korodira vodotopno kamnino. Proces je najbolj izrazit v bližini jamskih vhodov, kjer ob visokem temperaturnem gradientu zunanji zrak vstopa v jamo. Kondenzacijo in kondenzacijsko korozijo lahko pomembno povečajo kolonije netopirjev. Metabolizem netopirjev in razpadanje gvana sproščata toploto, vlago in kisline. Kondenzacijska korozija iz konvekcijskih tokov vlažnega zraka ustvarja zaobljene skalne oblike, kot so kupole, stropni kanali in korodirana siga. Kirenijsko gorovje na Cipru ima polsuho podnebje. Večina jam v tej raziskavi so odprte razpoke v prekristaljenem karbonatu (apnenec in dolomit) ali v sadri. Poleg teh obravnavamo tudi blodnjake v sadri, ki so se oblikovali v freatični coni in so v preteklosti delovali kot izviri. V njih najdemo stenske zajede, ki so nastale v epifreatični fazi. Ker je zrak poleti zelo suh, je kondenzacija omejena na zimski čas, ko se intenzivno izmenjuje zrak med jamsko in zunanjo atmosfero. Poleti prevladuje izhlapevanje, kar omogoča razvoj cvetačastih oblik v karbonatnih jamah ter sadrinih skorij, stalagmitov in stranskih obrob v jamah v sadri. Kolonija netopirjev v eni od polzaprtih dvoran v jami Smoky Cave verjetno vzdržuje visoko vlago tudi poleti. Posledica so močno izražene oblike kondenzacijske korozije (kupole) in stalna aktivna rast sige. V eni od jam smo izmerili visoko vsebnost SO2 in radona, ki je verjetno povezana z aktivno narivno tektoniko. Pet obravnavanih jam je tektonskega izvora in so verjetno nastale v kratkem obdobju hitrega dvigovanja v pleistocenu ter bile kasneje preoblikovane s kondenzacijsko korozijo. Nekatere jame v sadri so nastale skoraj izključno s kondenzacijsko korozijo, ki je preoblikovala prvotne majhne razpoke. Ciper je izjemno območje za podobne študije, saj lahko zaradi odsotnosti freatične faze večino zaobljenih jamskih oblik pripišemo kondenzacijski koroziji.Ključne besede: Vzhodno Sredozemlje, kondenzacijska korozija, gvano, Kirenijsko gorovje, jame v odprtih razpokah, hitri tektonski dvig, sadra, jamska mikroklima, pleistocen
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