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Sample records for african humid period

  1. Model, Proxy and Isotopic Perspectives on the East African Humid Period

    NASA Technical Reports Server (NTRS)

    Tierney, Jessica E.; Lewis, Sophie C.; Cook, Benjamin I.; LeGrande, Allegra N.; Schmidt, Gavin A.

    2011-01-01

    Both North and East Africa experienced more humid conditions during the early and mid-Holocene epoch (11,000-5000yr BP; 11-5 ka) relative to today. The North African Humid Period has been a major focus of paleoclimatic study, and represents a response of the hydrological cycle to the increase in boreal summer insolation and associated ocean, atmosphere and land surface feedbacks. Meanwhile, the mechanisms that caused the coeval East African Humid Period are poorly understood. Here, we use results from isotopeenabled coupled climate modeling experiments to investigate the cause of the East African Humid Period. The modeling results are interpreted alongside proxy records of both water balance and the isotopic composition of rainfall. Our simulations show that the orbitally-induced increase in dry season precipitation and the subsequent reduction in precipitation seasonality can explain the East African Humid Period, and this scenario agrees well with regional lake level and pollen paleoclimate data. Changes in zonal moisture flux from both the Atlantic and Indian Ocean account for the simulated increase in precipitation from June through November. Isotopic paleoclimate data and simulated changes in moisture source demonstrate that the western East African Rift Valley in particular experienced more humid conditions due to the influx of Atlantic moisture and enhanced convergence along the Congo Air Boundary. Our study demonstrates that zonal changes in moisture advection are an important determinant of climate variability in the East African region.

  2. African humid periods triggered the reactivation of a large river system in Western Sahara.

    PubMed

    Skonieczny, C; Paillou, P; Bory, A; Bayon, G; Biscara, L; Crosta, X; Eynaud, F; Malaizé, B; Revel, M; Aleman, N; Barusseau, J-P; Vernet, R; Lopez, S; Grousset, F

    2015-01-01

    The Sahara experienced several humid episodes during the late Quaternary, associated with the development of vast fluvial networks and enhanced freshwater delivery to the surrounding ocean margins. In particular, marine sediment records off Western Sahara indicate deposition of river-borne material at those times, implying sustained fluvial discharges along the West African margin. Today, however, no major river exists in this area; therefore, the origin of these sediments remains unclear. Here, using orbital radar satellite imagery, we present geomorphological data that reveal the existence of a large buried paleodrainage network on the Mauritanian coast. On the basis of evidence from the literature, we propose that reactivation of this major paleoriver during past humid periods contributed to the delivery of sediments to the Tropical Atlantic margin. This finding provides new insights for the interpretation of terrigenous sediment records off Western Africa, with important implications for our understanding of the paleohydrological history of the Sahara. PMID:26556052

  3. African humid periods triggered the reactivation of a large river system in Western Sahara

    PubMed Central

    Skonieczny, C.; Paillou, P.; Bory, A.; Bayon, G.; Biscara, L.; Crosta, X.; Eynaud, F.; Malaizé, B.; Revel, M.; Aleman, N.; Barusseau, J. -P.; Vernet, R.; Lopez, S.; Grousset, F.

    2015-01-01

    The Sahara experienced several humid episodes during the late Quaternary, associated with the development of vast fluvial networks and enhanced freshwater delivery to the surrounding ocean margins. In particular, marine sediment records off Western Sahara indicate deposition of river-borne material at those times, implying sustained fluvial discharges along the West African margin. Today, however, no major river exists in this area; therefore, the origin of these sediments remains unclear. Here, using orbital radar satellite imagery, we present geomorphological data that reveal the existence of a large buried paleodrainage network on the Mauritanian coast. On the basis of evidence from the literature, we propose that reactivation of this major paleoriver during past humid periods contributed to the delivery of sediments to the Tropical Atlantic margin. This finding provides new insights for the interpretation of terrigenous sediment records off Western Africa, with important implications for our understanding of the paleohydrological history of the Sahara. PMID:26556052

  4. The role of fall season tropical plumes in enhancing Saharan rainfall during the African Humid Period

    NASA Astrophysics Data System (ADS)

    Skinner, Christopher B.; Poulsen, Christopher J.

    2016-01-01

    The early Holocene to mid-Holocene African Humid Period (AHP) is marked by widespread rainfall throughout the present-day arid Sahara. Here we simulate early Holocene and mid-Holocene climate with the Community Atmosphere Model version 5 to explore the role of fall season dynamics in driving Saharan rainfall during the AHP. An enhanced summer monsoon during the AHP results in abundant fall season moisture throughout tropical Africa, particularly during the mid-Holocene. During the fall, extratropical troughs advect tropical moisture toward the Sahara in the form of concentrated plumes of water vapor and extend the Saharan rainy season into October. Fall season tropical plumes contribute up to 30% of annual Saharan rainfall during the mid-Holocene. Our results suggest that tropical plumes serve as an important mechanism for enhancing Saharan rainfall during the late AHP and that further understanding of changes in tropical plumes through time may provide valuable insights into past African hydroclimate change.

  5. A Spatiotemporal View of the African Humid Period from Leaf Wax Isotopes

    NASA Astrophysics Data System (ADS)

    Tierney, J. E.; deMenocal, P. B.

    2014-12-01

    The timing and abruptness of both the onset and termination of the African Humid Period (AHP) across the Sahara have been a subject of controversy, with some paleoclimate records indicating abrupt transitions, and others, gradual ones. Records of the hydrogen isotopic composition of leaf waxes (dDwax) spanning the AHP have proven to be key players in the debate, as dDwax appears to be a reliable proxy for aridity across semi-arid Africa. We present here four new dDwax chronologies from a latitudinal transect of marine sediment core sites offshore from the Sahara. Synthesizing these data with existing dDwax chronologies, we arrive at a new and detailed spatiotemporal picture of the AHP that reveals spatial patterns in both the timing and abruptness of the AHP termination.

  6. A mid-Holocene thermal maximum at the end of the African Humid Period

    NASA Astrophysics Data System (ADS)

    Berke, Melissa A.; Johnson, Thomas C.; Werne, Josef P.; Schouten, Stefan; Sinninghe Damsté, Jaap S.

    2012-10-01

    The termination of the African Humid Period (AHP) about 5 thousand years ago (ka) was the most dramatic climate shift in northern and equatorial Africa since the end of the Pleistocene. Based on TEX86 paleotemperature data from Lake Turkana, Kenya, we show that a temperature shift of 2-4 °C occurred over the two millennia spanning the end of the AHP, with the warmest conditions occurring at ˜5 ka. We note a similar shift, though of a smaller magnitude, in other East African temperature records from Lakes Malawi and Tanganyika, as well as Mt. Kilimanjaro. Additionally, we document the temperature history for the last 220 years from Lake Turkana that indicates the thermal anomaly at 5 ka was warmer than the present day Lake Turkana temperatures and on par with modern temperatures of Lakes Tanganyika and Malawi. We suggest that the thermal response at the end of the AHP may be linked to local insolation during September-November, when local air temperature rises to an annual maximum over Lakes Malawi and Tanganyika and a secondary maximum over Lake Turkana and Mt. Kilimanjaro. September-November insolation peaked at ˜5 ka and likely caused air and water temperatures in the region to rise to maxima at that time.

  7. « Younger-Dryas / African Humid Period »: a notable climatic transition over West Africa

    NASA Astrophysics Data System (ADS)

    Skonieczny, C.; Bory, A. J.; Bout-Roumazeilles, V.; Malaizé, B.; Grousset, F. E.; Abouchami, W.; Galer, S. J.; Francois, R. H.

    2013-05-01

    Every year, several hundreds teragrams of dust are emitted from the Sahara and Sahel regions. These mineral particles sensitively track variations in atmospheric circulation and continental aridity. Sediments of the Northeastern Atlantic Tropical Ocean (NEATO) are fed by this intense dust supply and comprise unique long-term archives of past dust emissions. Past modifications of dust characteristics in these sedimentary archives can provide precious information on changes in environmental conditions in source areas (aridity, weathering), as well as on changes in the characteristics of their atmospheric transport (pathways and strength). Over Africa, gradual increases in local insolation due to changes in the Earth's orbit are accompanied by a migration of the precipitation monsoon-system (associated with the InterTropical Convergence Zone, ITCZ) toward the North. This displacement leads to decrease in West African mineral dust emission. Consequently, Saharan and Sahelian dust deposited in the NEATO sedimentary archives represent an exceptional opportunity to document the environmental and climatic changes that have taken place in West Africa throughout the Quaternary and beyond (Rea, 1994). Here we document changes in the terrigenous supplies to the NETAO throughout the last deglaciation using the marine sediment core MD03-2705 located off Mauritania (18°05N; 21°09W; 3085m water depth) and retrieved from a bathymetric dome, 300 meters above the surrounding seafloor. Considering this particular environmental setting, the terrigenous fraction in this record is assumed to be predominantly of aeolian origin. Multi-proxy analyses of the carbonate-free fraction of the sediment were carried-out, including dust fluxes, grain-size, clay mineralogy and geochemical measurements (major and trace elements as well as Sr & Nd isotopes). We will discuss the most significant changes recorded over the studied period: levels dated from the Younger Dryas and the subsequent African

  8. Arctic climate response to the termination of the African Humid Period

    NASA Astrophysics Data System (ADS)

    Muschitiello, Francesco; Zhang, Qiong; Sundqvist, Hanna S.; Davies, Frazer J.; Renssen, Hans

    2015-10-01

    The Earth's climate response to the rapid vegetation collapse at the termination of the African Humid Period (AHP) (5.5-5.0 kyr BP) is still lacking a comprehensive investigation. Here we discuss the sensitivity of mid-Holocene Arctic climate to changes in albedo brought by a rapid desertification of the Sahara. By comparing a network of surface temperature reconstructions with output from a coupled global climate model, we find that, through a system of land-atmosphere feedbacks, the end of the AHP reduced the atmospheric and oceanic poleward heat transport from tropical to high northern latitudes. This entails a general weakening of the mid-latitude Westerlies, which results in a shift towards cooling over the Arctic and North Atlantic regions, and a change from positive to negative Arctic Oscillation-like conditions. This mechanism would explain the sign of rapid hydro-climatic perturbations recorded in several reconstructions from high northern latitudes at 5.5-5.0 kyr BP, suggesting that these regions are sensitive to changes in Saharan land cover during the present interglacial. This is central in the debate surrounding Arctic climate amplification and future projections for subtropical precipitation changes.

  9. Water level changes for Lake Turkana and climate variability during the African Humid Period

    NASA Astrophysics Data System (ADS)

    Bloszies, C.; Forman, S. L.; Wright, D. K.

    2013-12-01

    The chronology of East African paleoclimate suggests the transition through the African Humid Period (AHP) at ca. 15 to 5 ka was a binary shift from wet conditions in the Late Pleistocene to current aridity. Previous studies indicate that water levels for Lake Turkana for the AHP were stable at ~88 to 98 m above current level with outflow into the White Nile Basin. This study of relict beaches around Lake Turkana indicates surprisingly >50 m variability in water level between 14 and 4 ka. The elevation of past water level is constrained by barometric and GPS-based altimetry of relict beaches and age control by 14C dating of associated mollusks and OSL dating of quartz grains from surrounding littoral and sublittoral deposits. We also include well provenanced lake level data from prior studies to constrain more fully the timing and height of water level fluctuations in the Late Quaternary. Additionally, previous studies indicate that peak water levels may be regionally amplified by increased precipitation causing overflow into the Lake Turkana Basin from the adjacent Suguta and Chew Bahir basins, particularly during high stands at ca. >8.5 ka and at 6.3 ka. Our analysis of the Lake Turkana strandplain reveals that water level may have varied by × 60 m, potentially reaching the outlet elevation at ca.11.3, 10.3, 9.0, 6.3 and 5.1 ka. There are other possible high stands at ca. 13.0, 8.4, 7.8 and 7.0 ka with limited elevational and age constraints; it is unknown if these lake stands reached the outlet elevation. Evidence from relict strand plains indicate that lake level was probably below 20 m since ca. 4.5 ka, though there were two noticeable high stands up to >12 to 18 m at ca. 830 years ago and <100 years, the latter consistent with the historic record of lake levels. Inferences on the source of moisture to sustain these many high stands are based on the isotopic data on leaf wax (δDwax) from lakes Tanganika and Victoria and associated sea surface temperature

  10. Paleohydrological change in the Turkana Basin at the termination of the African Humid Period

    NASA Astrophysics Data System (ADS)

    Vonhof, Hubert; van der Lubbe, Jeroen; Joordens, Josephine; Feibel, Craig; Junginger, Annett; Garcin, Yannick; Krause-Nehring, Jacqueline; Beck, Catherine; Johnson, Thomas

    2016-04-01

    One of the most significant features of Holocene climate change in East Africa is the termination of the African Humid Period (AHP), which occurred at ~ 5 ka. Many lakes in the East African Rift System (EARS) were strongly affected by these climatic changes, generally exhibiting much higher lake levels before the termination of the AHP than after. One of the larger lakes in the EARS, is Lake Turkana which was filled to overflow level for much of the early Holocene and experienced a dramatic ~70 meter lake level drop at ~5 ka, turning it into the terminal lake system as it still is today. The precise hydrological response of Lake Turkana to climate change at the termination of the AHP is potentially complex, because it is situated at the cross roads of two large atmospheric convection systems; the Intertropical Convergence Zone (ITCZ) and the Congo Air Boundary (CAB). Shifting of these atmospheric systems at the end of the AHP dramatically re-organised spatial rainfall patterns over the Turkana Basin catchment, causing a shift in runoff contributions from the different sub-catchments of the Turkana Basin. Here, we present a Holocene Turkana lake water Sr isotope reconstruction based on the analysis of well-dated lacustrine ostracods and shells, which reveals consistently high Sr isotope values for the early Holocene, followed by a significant, but gradual drop in Sr isotope ratios across the AHP termination. Since lacustrine Sr isotope ratios are a runoff provenance indicator in this setting, such dramatic lacustrine Sr isotope change points towards a significant (climate-driven) reorganisation of runoff contributions from different sub-catchments to Lake Turkana. In more detail, the Sr isotope reconstruction strongly suggests that changes in runoff patterns at the termination of the AHP in the Turkana Basin were gradual. The higher Sr isotope ratios during the Early Holocene indicate significant runoff contribution from a more radiogenic sub-catchment at that time

  11. Dynamics of Late Quaternary North African humid periods documented in the clay mineral record of central Aegean Sea sediments

    NASA Astrophysics Data System (ADS)

    Ehrmann, Werner; Seidel, Martin; Schmiedl, Gerhard

    2013-08-01

    The ratio between the clay minerals kaolinite and chlorite has been investigated in high resolution in a late Quaternary sediment core from the central Aegean Sea. The record spans the last ca. 105 ka. The kaolinite/chlorite ratio was used to reconstruct the fine-grained aeolian dust influx from the North African deserts, mainly derived from desiccated lake depressions. It therewith can be used as a proxy for wind activity, aridity and vegetation cover in the source area. The data document three major humid phases in North Africa bracketing the formation of sapropel layers S4, S3 and S1. They occur at > 105-95 ka, 83.5-72 ka and 14-2 ka. The first two phases are characterised by relatively abrupt lower and upper boundaries suggesting a non-linear response of vegetation to precipitation, with critical hydrological thresholds. In contrast, the onset and termination of the last humid period were more gradual. Highest kaolinite/chlorite ratios indicating strongest aeolian transport and aridity occur during Marine Isotope Stage (MIS) 5b, at ca. 95-84 ka. The long-term decrease in kaolinite/chlorite ratios during the last glacial period indicates a gradual decline of deflatable lake sediments in the source areas.

  12. Central southern Africa at the time of the African Humid Period: A new analysis of Holocene palaeoenvironmental and palaeoclimate data.

    NASA Astrophysics Data System (ADS)

    Burrough, Sallie; Thomas, David

    2014-05-01

    The Holocene African Humid Period (c 14.8-5.5 ka) is now recognised in high-resolution records from western Africa as well as in tropical Africa north of the equator. Establishing a clear picture of Holocene environmental changes from palaeodata in central southern Africa is, however, proving both difficult and contentious. This is because in dryland systems in particular it can be difficult to distinguish the effects of sub-millennial scale regional climatic variability from those of major externally-forced global climate changes. We analyse and review existing records for central southern Africa, and neighbouring areas affected by the same climate systems, to attempt to build a clearer spatial picture of regional hydrological system responses during the Holocene. We suggest palaeodata, including new data from Makgadikgadi basin barchan dunes indicate mid-late Holocene aridity following a period of marked hydrological dynamism extending from the early Holocene. We propose that present-day conditions in central southern Africa are relatively stable compared to the early and mid-Holocene and infer that this period of relative stability in the landscape has occurred since ca. 2 ka. We explain Holocene hydrological changes through analysis of changing zonal climatic influences linked to Congo Air Boundary (CAB) and Intertropical Convergence Zone (ITCZ) dynamics, the effects of which filter into the region via complex drainage basin dynamics. It is proposed that, sensu stricto, the AHP was not a spatially uniform feature of early Holocene central southern Africa.

  13. Hydrogen isotopes of leaf lipids indicate gradual hydrologic transition at the end of the African Humid Period

    NASA Astrophysics Data System (ADS)

    Beckmann, Britta; Haese, Barbara; Werner, Martin; Schefuß, Enno

    2013-04-01

    The hydrologic evolution of the NW African monsoon system over the Holocene, in particular during abrupt climate changes like the end of the African Humid Period (AHP) is not yet fully understood. The dust record at ODP Site 658C (DeMenocal et al., 2000) for example suggests an abrupt end of the AHP with a sudden desertification in the mid-Holocene. Contrastingly, a gradual transition to drier conditions at the end of the AHP has been detected in pollen records from lake sedimentary archives from northern Chad (Kröpelin et al., 2008) and northeastern Nigeria (Salzmann et al., 2002). However, neither dust nor pollen data can serve as immediate proxy for aridity itself, but rather reflect responses to changes in the hydrological regime. To test the abruptness of the end of the AHP and unravel late Holocene hydrologic change, we combine compound-specific carbon and hydrogen isotope analyses (δ13C, δD) of plant lipids covering the past 14ka with simulations of water isotope composition in an Earth System Model. We extracted terrestrial biomarkers (long-chain n-alkanes) from the high resolution marine sedimentary core GeoB7920-2 taken in immediate proximity to ODP Site 658C off the Sahara-Sahel transition in NW Africa. Because plants use environmental water (in the Sahel mainly from precipitation) as hydrogen source, changes in the δD signature of the plant-derived biomarkers can be attributed to isotopic changes in rainfall and ultimately to changes in the hydrological cycle on the continent. The n-alkanes show typical terrestrial plant signatures; δ13C values indicate predominance (60-100%) of C4-type plants, i.e., warm-season grasses. δD values of the most abundant n-C31 alkane, vary between -140‰ and -165‰ VSMOW. Generally, the AHP is characterized by lower δD values, indicating more rainfall and humid conditions in NW Africa. Compound-specific plant-wax isotope data from GeoB 7920-2 suggest a gradual transition in continental hydrology at the end of the

  14. Central southern Africa at the time of the African Humid Period: a new analysis of Holocene palaeoenvironmental and palaeoclimate data

    NASA Astrophysics Data System (ADS)

    Burrough, S. L.; Thomas, D. S. G.

    2013-11-01

    The Holocene African Humid Period (c 14.8-5.5 ka) is now recognised in high-resolution records from western Africa as well as in tropical Africa north of the equator. Establishing a clear picture of Late Quaternary, including Holocene, environmental changes in central southern Africa is proving both difficult and contentious. This is because in dryland systems in particular it can be difficult to distinguish the effects of sub-millennial scale regional climatic variability from those of major externally-forced global climate changes, and because it is essential to distinguish records of environmental drivers from those of environmental responses. We analyse and review existing records for central southern Africa, and neighbouring areas affected by the same climate systems, to understand the primary controls of regional hydrological systems during the Holocene. We then present new data from Makgadikgadi basin barchan dunes that indicate mid-late Holocene aridity following a period of marked hydrological dynamism extending from the early Holocene. We suggest that present-day conditions in central southern Africa are relatively stable compared to the early and mid-Holocene and infer that this period of relative stability in the landscape has occurred since ca 2 ka. We explain Holocene hydrological changes through analysis of changing zonal climatic influences linked to Congo Air Boundary (CAB) and Intertropical Convergence Zone (ITCZ) dynamics, the effects of which filter into the region via complex drainage basin dynamics. It is proposed that, sensu stricto, the AHP was not a spatially uniform feature of early Holocene central southern Africa.

  15. Palynological evidence for gradual vegetation and climate changes during the African Humid Period termination at 13°N from a Mega-Lake Chad sedimentary sequence

    NASA Astrophysics Data System (ADS)

    Amaral, P. G. C.; Vincens, A.; Guiot, J.; Buchet, G.; Deschamps, P.; Doumnang, J.-C.; Sylvestre, F.

    2013-01-01

    Located at the transition between the Saharan and Sahelian zones, at the center of one of the largest endorheic basins, Lake Chad is ideally located to record regional environmental changes that occurred in the past. However, until now, no Holocene archive was directly cored in this lake. In this paper, we present pollen data from the first sedimentary sequence collected in Lake Chad (13° N; 14° E; Sahel region). Dated between ca. 6700 and ca. 5000 cal yr BP, this record is continuous and encompasses part of the termination of the African Humid Period (AHP). Vegetation reconstructions are based on standard analyses of pollen diagrams and are strengthened by quantitative approaches. Potential biomes are reconstructed using the biomization method and mean annual precipitation (Pann) is estimated using the modern analogues technique. Results show that, between ca. 6700 and ca. 6050 cal yr BP, a vegetation close to humid woodland or humid savanna, including elements currently found further southward, thrived in the vicinity of the Mega-Lake Chad in place of the modern dry woodland, steppe and desert vegetation. At the same time, montane forest populations extended further southward on the Adamawa Plateau. The high abundance of lowland humid pollen taxa, particularly of Uapaca, is interpreted as the result of a northward migration of the corresponding plants during the AHP. This preferential zonal occurrence of these taxa in Lake Chad Basin (LCB) (rather than extrazonal) is driven by more humid local and regional climate conditions at this latitude, as shown by mean Pann estimated values of ca. 800 (-400/+700) mm during this period. However, we cannot rule out that an increase of the Chari-Logone inputs into the Mega-Lake Chad might have also contributed to control the abundance of these taxa. Changes in the structure and floristic composition of the vegetation towards more open and drier formations occurred after ca. 6050 cal yr BP, following a decrease in mean Pann

  16. Palynological evidence for gradual vegetation and climate changes during the "African Humid Period" termination at 13° N from a Mega-Lake Chad sedimentary sequence

    NASA Astrophysics Data System (ADS)

    Amaral, P. G. C.; Vincens, A.; Guiot, J.; Buchet, G.; Deschamps, P.; Doumnang, J.-C.; Sylvestre, F.

    2012-06-01

    Located at the transition between the Saharian and Sahelian zones, at the center of one of the largest endoreic basins, the Lake Chad is ideally located to record regional environmental changes that occurred in the past. However, until now, no continuous archive from Lake Chad covering the Holocene has been studied. In this paper, we present pollen data from the first Holocene sedimentary sequence collected in Lake Chad (13° N; 14° E; Sahel region). Dated between ca. 6700 and ca. 5000 cal yr BP, this record encompasses the termination of the African Humid Period (AHP). Vegetational reconstructions are based on standard analyses of the pollen diagrams and are strengthened by quantitative approaches. Potential biomes that occurred at that time around Mega-Lake Chad are reconstructed using the biomization method and mean annual precipitation is estimated using the modern analogues technique. Results show that between ca. 6700 and ca. 6050 cal yr BP, a vegetation close to humid woodland or humid savanna, including elements currently found much further southward, thrived in the vicinity and/or the extra-local environment of the Mega-Lake Chad in place of the modern steppe, dry woodland and desert vegetation observed today. At the same time, montane forest populations extended further southward on the Adamawa plateau. This vegetation distribution is supported by biome reconstructions as well as by mean annual precipitation estimates of ca. 800 (-400/+700) mm for the period. The high abundance of lowland humid pollen taxa is interpreted as the result of a northward migration of the corresponding plants during the AHP driven by more favorable climatic conditions. Our interpretation in favor of a regional vegetation response to climatic changes is supported by other pollen data from several Northwestern African records. However, we cannot rule out that an increase of Chari-Logone inputs into the Mega-Lake Chad due to variations in hydrological regime might have

  17. Variations in water level for Lake Turkana in the past 8500 years near Mt. Porr, Kenya and the transition from the African Humid Period to Holocene aridity

    NASA Astrophysics Data System (ADS)

    Forman, Steven L.; Wright, David K.; Bloszies, Christopher

    2014-08-01

    A stratigraphic and geomorphic study of relict beaches up to 80 m above current water level of Lake Turkana reveal four major lake level fluctuations of >50 m between ca 8.5 and 4.5 ka during the transition from the African Humid Period to Holocene aridity. We hypothesize that high stands of Lake Turkana reflect complex hydrological processes with variability in Atlantic and Indian Ocean-derived moisture into East Africa, ultimately linked to changes in sea surface temperatures (SSTs). Lake level rise was also amplified regionally by increased precipitation causing overflow from the adjacent Suguta and Chew Bahir basins, particularly during high stands at ca >8.5 ka and at 6.4 ka. The timing of transgressive and regressive events is constrained by 14C dating of carefully selected lacustrine mollusks, incorporation of previous shell ages with sufficient elevational control, and OSL dating of quartz grains from littoral and sublittoral deposits by a multiple aliquot regeneration (MAR) approach. There was a high water level up to at least 70 m at >8.5 ka that probably reached the spillover limit ˜100 m. A brief (<500 yr) high stand up to at least 50 m at ca 7 ka appears to be coincident with warm postglacial SSTs in the western Indian Ocean and thus may reflect a strengthened East African Monsoon, though some precipitation was probably derived from Atlantic sources as well. A pronounced high stand inferred at ca 6.4 ka, possibly up to 100 m, is associated with warming across the Indian Ocean and equatorward compression of the ITCZ, thus reflecting a strengthened East African Monsoon. A high stand occurred at ca 5.5-5.0 ka up to at least 80 m, with a precipitous drop in lake level by 4.6 ka. Evidence from relict Porr strand plain indicate that lake level was probably below 20 m since ca 4.5 ka, though there were two noticeable high stands up to 12-20 m at ca 830 years ago and <100 years, the latter age is consistent with the historic record.

  18. Coherent monsoonal changes in the northern tropics revealed by Chadian lakes (L. Chad and Yoa) sedimentary archives during the African Humid Period

    NASA Astrophysics Data System (ADS)

    Sylvestre, Florence; Kroepelin, Stefan; Pierre, Deschamps; Christine, Cocquyt; Nicolas, Waldmann; Kazuyo, Tachikawa; Amaral Paula, Do; Doriane, Delanghe; Guillaume, Jouve; Edouard, Bard; Camille, Bouchez; Jean-Claude, Doumnang; Jean-Charles, Mazur; Martin, Melles; Guillemette, Menot; Frauke, Rostek; Nicolas, Thouveny; Volkner, Wennrich

    2016-04-01

    In northern African tropics, it is now well established that the Last Glacial Maximum (LGM) was extremely dry followed by a wetter Holocene. Numerous palaeolake records reveal a fairly consistent pattern of a moister early Holocene resulting in a green Sahara followed by the onset of aridification about 4000 years ago. These palaeoenvironmental conditions are deciphered from several continental records distributed over the sub-Saharan zone and including diverse environments. However, pronounced differences in the timing and amplitude of these moisture changes inferred from sedimentary records point to both regional climatic variability change and site-specific influences of local topographic-hydrogeological factors which biased the evolution of water balance reconstructed from individual lacustrine archives. Here we present hydrological reconstructions from Chadian lakes, i.e. Lake Chad (c. 13°N) and Lake Yoa (19°N). Because of their location, both records allow to reconstruct lake level fluctuations and environmental changes according to a gradient from Sahelian to Saharan latitudes. Whereas Lake Chad is considered as a good sensor of climatic changes because of its large drainage basin covering 610,000 km2 in the Sudanian belt, Lake Yoa logs the northern precipitation changes in the Sahara. Combining sedimentological (laser diffraction grain size) and geochemical (XRF analysis) data associated with bio-indicators proxies (diatoms, pollen), we compare lake-level fluctuations and environmental changes during the last 12,000 years. After the hyperarid Last Glacial Maximum period during which dunes covered the Lake Chad basin, both lake records indicate an onset of more humid conditions between 12.5-11 ka cal BP. These resulted in lacustrine transgressions approaching their maximum extension at c. 10.5 ka cal BP. The lacustrine phase was probably interrupted by a relatively short drying event occurring around 8.2 ka cal BP which is well-defined in Lake Yoa by

  19. Response of African humid tropical forests to recent rainfall anomalies

    PubMed Central

    Asefi-Najafabady, Salvi; Saatchi, Sassan

    2013-01-01

    During the last decade, strong negative rainfall anomalies resulting from increased sea surface temperature in the tropical Atlantic have caused extensive droughts in rainforests of western Amazonia, exerting persistent effects on the forest canopy. In contrast, there have been no significant impacts on rainforests of West and Central Africa during the same period, despite large-scale droughts and rainfall anomalies during the same period. Using a combination of rainfall observations from meteorological stations from the Climate Research Unit (CRU; 1950–2009) and satellite observations of the Tropical Rainfall Measuring Mission (TRMM; 1998–2010), we show that West and Central Africa experienced strong negative water deficit (WD) anomalies over the last decade, particularly in 2005, 2006 and 2007. These anomalies were a continuation of an increasing drying trend in the region that started in the 1970s. We monitored the response of forests to extreme rainfall anomalies of the past decade by analysing the microwave scatterometer data from QuickSCAT (1999–2009) sensitive to variations in canopy water content and structure. Unlike in Amazonia, we found no significant impacts of extreme WD events on forests of Central Africa, suggesting potential adaptability of these forests to short-term severe droughts. Only forests near the savanna boundary in West Africa and in fragmented landscapes of the northern Congo Basin responded to extreme droughts with widespread canopy disturbance that lasted only during the period of WD. Time-series analyses of CRU and TRMM data show most regions in Central and West Africa experience seasonal or decadal extreme WDs (less than −600 mm). We hypothesize that the long-term historical extreme WDs with gradual drying trends in the 1970s have increased the adaptability of humid tropical forests in Africa to droughts. PMID:23878335

  20. Palaeohydrology of the Fazzan Basin, Libyan Sahara: Evidence for multiple phases of North African humidity.

    NASA Astrophysics Data System (ADS)

    Armitage, S. J.; White, K.; Drake, N.

    2008-12-01

    The Fazzan is a large closed basin with an area of 450,000 km2, located in south-western Libya. The present-day climate is hyper-arid. Modern human occupation is restricted to oases, notably at the foot of the Messak Sattafat, a Nubian Sandstone escarpment which divides the Fazzan into two sub-basins. However widespread lithic scatters with varying inferred ages, and numerous Holocene hearth fields, indicate that the Fazzan has a long history of human occupation. In addition, regionally extensive lake deposits attest to the presence of a large palaeolake, here termed Lake Mega-Fazzan, at various periods in the past. Although the Sahara contains evidence for several other large palaeolakes, Lake Mega-Fazzan is the only one fed exclusively by rivers draining the Sahara proper. Thus, the Lake Mega-Fazzan sediments and archaeological remains provide an important resource for advancing our understanding of climate change in this part of the Sahara. Optically stimulated luminescence (OSL) dating techniques have been applied to a range of lacustrine deposits, and more experimentally to the Holocene hearth fields, to provide an internally consistent chronology for the Fazzan record. Results indicate that sediments within the Fazzan Basin record a very long history of palaeohydrological change. The oldest lacustrine sediments are beyond the range of conventional OSL dating techniques, but younger humid periods during oxygen isotope stages 11, 5 and 1 are recognised. Initial results from one hearth field also indicate that OSL has the potential to reveal human responses to changes in hydrology during the Holocene. These results, when compared with similar studies of adjacent closed basins, indicate that the Sahara may not always have provided as formidable a barrier to faunal migration as it does at present. The implications of this finding for our understanding of North African palaeoclimate and biogeography will be discussed.

  1. Spatial analysis of relative humidity during ungauged periods in a mountainous region

    NASA Astrophysics Data System (ADS)

    Um, Myoung-Jin; Kim, Yeonjoo

    2016-06-01

    Although atmospheric humidity influences environmental and agricultural conditions, thereby influencing plant growth, human health, and air pollution, efforts to develop spatial maps of atmospheric humidity using statistical approaches have thus far been limited. This study therefore aims to develop statistical approaches for inferring the spatial distribution of relative humidity (RH) for a mountainous island, for which data are not uniformly available across the region. A multiple regression analysis based on various mathematical models was used to identify the optimal model for estimating monthly RH by incorporating not only temperature but also location and elevation. Based on the regression analysis, we extended the monthly RH data from weather stations to cover the ungauged periods when no RH observations were available. Then, two different types of station-based data, the observational data and the data extended via the regression model, were used to form grid-based data with a resolution of 100 m. The grid-based data that used the extended station-based data captured the increasing RH trend along an elevation gradient. Furthermore, annual RH values averaged over the regions were examined. Decreasing temporal trends were found in most cases, with magnitudes varying based on the season and region.

  2. Correction of humidity bias for Vaisala RS80-A and MODEM sondes during AMMA 2006 observing period

    NASA Astrophysics Data System (ADS)

    Nuret, M.; Lafore, J. P.; Bock, O.; Guichard, F.

    2009-04-01

    During the African Monsoon Multidisciplinary Analyses (AMMA) program whose Special Observing Period took place over West Africa in 2006, a major effort has been devoted to monitor the atmosphere and its water cycle. The radiosoundings network has been upgraded and enhanced, and GPS receivers deployed. The various sondes used in the campaign exhibit a significant humidity bias: • dry bias for Vaisala RS80-A at daytime and nighttime, for RS92 and MODEM M2K2 at daytime only • moist bias for MODEM M2K2 and Vaisala RS92 at nighttime This presentation makes use of a simple but robust statistical approach to correct the bias. Validation against independent GPS data shows that a first correction (to be implemented in the database in early 2009), removes the night bias for MODEM and Vaisala RS-80A, and strongly reduces it for daytime RS80-A launches. The correction dramatically modifies the CAPE, which becomes much more in line with expected values over the region. A second correction (under development) will address the remaining daytime bias, thanks to an inter-comparison exercise performed in Niamey in September 2008.

  3. [Thyrotoxic hypokalemic periodic paralysis in patients of African descent].

    PubMed

    Maia, Morgana Lima e; Trevisam, Paula Grasiele Carvalho; Minicucci, Marcos; Mazeto, Glaucia M F S; Azevedo, Paula S

    2014-10-01

    Thyrotoxic hypokalemic periodic paralysis (THPP) is an endocrine emergency marked by recurrent attacks of muscle weakness associated with hypokalemia and thyrotoxicosis. Asiatic male patients are most often affected. On the other hand, African descents rarely present this disease. The case described shows an afrodescendant patient with hypokalemia and tetraparesis, whose diagnosis of hyperthyroidism was considered during this crisis. The THPP, although rare, is potentially lethal. Therefore, in cases of flaccid paresis crisis this diagnosis should always be considered, especially if associated with hypokalemia. In this situation, if no previous diagnosis of hyperthyroidism, this should also be regarded. PMID:25372590

  4. Reanalysis of upper tropospheric humidity data of the MOZAIC programme for the period 1994 to 2009

    NASA Astrophysics Data System (ADS)

    Petzold, Andreas; Smit, Herman; Rohs, Susanne; Neis, Patrick; Thomas, Karin; Thouret, Valerie; Nedelec, Philippe; Boulanger, Damien

    2014-05-01

    Water vapour plays a dominant role in the atmospheric energy budget and greenhouse effect. It is one of the key drivers for atmospheric transport and has a strong influence on the oxidative capacity of the atmosphere. Therefore, it takes a key position in the description of climate, chemistry and their interactions. Due to a range of small-scale dynamical and microphysical processes, the abundance of upper tropospheric humidity (UTH) is highly variable on spatial and temporal scales that cannot be resolved, neither by the global radiosondes network nor by satellites. Data with high spatial and temporal resolution for relative humidity are provided by the in-situ measurements aboard civil passenger aircraft from the MOZAIC/IAGOS-project (www.iagos.org) since 1994. The data set emerging from this long-term observation programme builds the backbone of climatologies and trend analyses of UTH. First analyses of MOZAIC measurements for the period 1994 to 1999 showed that the upper troposphere (9 to 13 km altitude, which corresponds to the aircraft cruise level) is much wetter than reflected in the model analyses of the ECMWF (European Centre for Medium Range Weather Forecast). The MOZAIC data has also demonstrated that ice supersaturation is often large enough to let contrails develop into cirrus but not large enough to let cirrus clouds form naturally. In our study, the MOZAIC data set on relative humidity (RH) was reanalysed for the period 1994 to 2009. Previous analyses of probability distribution functions (PDF) of UTH data from MOZAIC observations from the year 2000 and later indicated a bias towards higher RH values. As a result, the PDF of UTH exhibits a maximum at RH over ice (RH_ice) of approx. 130% instead of the maximum at 100% RH_ice observed in the period 1994 to 1999. Since this bias towards higher RH_ice values is in contradiction to physical understanding and to observations made inside equilibrated cirrus clouds, an in-depth reanalysis of the MOZAIC data

  5. Records of human activity during the late-Holocene in the soils of the African dense humid forest

    NASA Astrophysics Data System (ADS)

    Morin-Rivat, Julie; Bentaleb, Ilham; Biwolé, Achille; Bourland, Nils; Bremond, Laurent; Daïnou, Kasso; Fayolle, Adeline; Gillet, Jean-François; Gorel, Anaïs; Gourlet-Fleury, Sylvie; Hardy, Olivier; Livingstone Smith, Alexandre; Oslisly, Richard; Vleminckx, Jason; Beeckman, Hans; Doucet, Jean-Louis

    2014-05-01

    Recently, several authors gathered data about the presence of past human populations in tropical regions covered by dense forest nowadays. In Central Africa, there is a growing body of evidence for past human settlements along the Atlantic coast, but very little information is available further inland. In the perspective, soil records seem to be the most appropriated so as to appraise the spatial and temporal extent of human activity in the African dense humid forest. In this paper, we thus aimed to present a synthesis of the archaeological and archaeobotanical data obtained during several fieldwork campaigns in an archaeologically unexplored area of 200,000 km² located in southern Cameroon and the northern Republic of Congo. A total of 275 test pits, among them 30 pedological pits up to 150 cm deep, were excavated in the study area. So as to get a long temporal scale as well as a fine resolution spatial scale, we quantified wood charcoal and charred endocarps in soil samples by layers of 10 cm taken for 100 pits located along transects of systematic sampling. Spatial projections were performed using statistics together with multivariate analyses. AMS radiocarbon dating allowed interpreting the temporal framework. Evidence of past human activities through either artifacts or charred botanical remains was observed in all pits, in particular with the ubiquitous presence of charcoal at each site. Main charcoal peaks were interpreted as fields (slash-and-burn agriculture) in the vicinity of ancient villages, the later marked by the presence of both potsherds and oil palm endocarps. The dichotomy of these kinds of activities may have impacted differentially the environment during the past. The set of 73 radiocarbon dates extending from 15,000 BP to the present time provided more dates in the late-Holocene showing a bimodal distribution which was interpreted as two phases of human expansion with an intermediate phase of population crash. The 2300-1300 BP phase is

  6. Humidity Sensing Using Gelatin and Cobalt Chloride Coating on Indium Tin Oxide-Coated Long-Period Grating

    NASA Astrophysics Data System (ADS)

    Nidhi; Kaler, R. S.; Kapur, Pawan

    2014-01-01

    In this article, humidity sensing using gelatin and cobalt chloride on indium tin oxide coated long-period gratings was proposed and demonstrated. First, a thin overlay of indium tin oxide was deposited on a long-period grating by using a simple dip coating methodology. Similarly, a combination of gelatin and cobalt chloride was deposited onto the indium tin oxide layer. A field emission scanning electron microscope provided detailed evidence of the attachment of amalgamation on long-period gratings. The designed sensor showed a significant shift in the resonance wavelength when the relative humidity varied from 40% to 95%, with a sensitivity of 0.12 nm/% relative humidity and an accuracy of 98.45%.

  7. A review of groundwater recharge estimation in humid and semi-arid African regions

    NASA Astrophysics Data System (ADS)

    Chung, Il-Moon; Kim, Nam Won

    2016-04-01

    For the review of African recharge estimation, the distinct methods such as the geochemical approach, a method using groundwater level data, the streamflow method, and the water balance methods were first outlined. The major challenge of an African recharge study is the lack of basic data. Thus, this work suggests how to deal with this limitation and from future perspective using recently developed technologies such as RS, GIS, etc. With the rapid growth of information technology, more and more data, in terms of both volume and variety, are expected to be made available on the internet in the near future. RS technology has a great potential to revolutionize the groundwater development and management in the future by providing unique and completely new hydrological and hydrogeological data. However, at present, the RS data should be considered along with the conventional field data. In spite of the weaknesses of water balance methods in semi-arid areas, recently developed water balance methods combined with GIS technology are powerful tools for estimating groundwater re-charge, when spatial-temporal variability of components in water balance is taken into account (Lerner et al., 1990; De Vries and Simmers, 2002; Eilers et al., 2007).When enough data sets are available, integrated surface-groundwater modeling is recommended for more accurate estimation of groundwater recharge and discharge. Acknowledgements This work was supported by a grant(14RDRP-B076275-01-000000) from Infrastructure and transportation technology promotion research Program funded by the Ministry of Land, Infrastructure and Transport of Korean government.

  8. Technical Note: Reanalysis of upper troposphere humidity data from the MOZAIC programme for the period 1994 to 2009

    NASA Astrophysics Data System (ADS)

    Smit, H. G. J.; Rohs, S.; Neis, P.; Boulanger, D.; Krämer, M.; Wahner, A.; Petzold, A.

    2014-12-01

    In situ observational data on the relative humidity (RH) in the upper troposphere and lowermost stratosphere (UT/LS), or tropopause region, collected aboard civil passenger aircraft in the MOZAIC (Measurements of OZone, water vapour, carbon monoxide and nitrogen oxides by in-service AIrbus airCraft) programme were reanalysed for the period 2000 to 2009. Previous analyses of probability distribution functions (PDFs) of upper troposphere humidity (UTH) data from MOZAIC observations from year 2000 and later indicated a bias of UTH data towards higher RH values compared to data of the period 1994 to 1999. As a result, the PDF of UTH data show a substantial fraction of observations above 100% relative humidity with respect to liquid water. Such supersaturations, however, do not occur in the atmosphere because there is always a sufficient number of condensation nuclei available, that trigger condensation as soon as liquid saturation is slightly exceeded. An in-depth reanalysis of the data set identified a coding error in the calibration procedure from year 2000 on. The error did not affect earlier data from 1994 to 1999. The full data set for 2000-2009 was reanalysed applying the corrected calibration procedure. Applied correction schemes and a revised error analysis are presented along with the reanalysed PDF of relative humidity with respect to liquid water (RHliquid) and ice (RHice).

  9. Analysis of beam interference reflected from atomic force microscope tip and periodic silicon surface under various humidity conditions

    NASA Astrophysics Data System (ADS)

    Banerjee, Hans P.; Weerasinghe, Asanka T.; Lyuksyutov, Sergei F.

    2012-10-01

    Dynamical sensing based on combination of classical optical effects and atomic force microscopy (AFM) presents challenge for analysis of the forces at the nanoscale and beyond. An interference effect between light reflected from an AFM cantilever and highly reflective silicon surface of the calibration grating was studied for relative humidity (RH) varied between 9 and 60%. Force-distance analysis indicates on separation of capillary, van der Waals, adhesion, and electrostatic forces. The measurements performed in contact AFM mode suggest that the period of interference pattern observed in displacement curves is a function of humidity and varies between 293 nm at RH = 9% and 335 nm at RH > 50% with standard deviation less than 8 nm. Clear change of the interference period suggests that other than hardwarerelated factors may be involved in the formation of the interference in force-distance curves.

  10. Technical Note: Reanalysis of upper troposphere humidity data from the MOZAIC programme for the period 1994 to 2009

    NASA Astrophysics Data System (ADS)

    Smit, H. G. J.; Rohs, S.; Neis, P.; Boulanger, D.; Krämer, M.; Wahner, A.; Petzold, A.

    2014-07-01

    In-situ observational data on the relative humidity (RH) in the upper troposphere and lowermost stratosphere (UT/LS), or tropopause region, respectively, collected aboard civil passenger aircraft in the MOZAIC (Measurements of OZone, water vapour, carbon monoxide and nitrogen oxides by in-service AIrbus airCraft) programme were reanalysed for the period 2000 to 2009. Previous analyses of probability distribution functions (PDF) of upper troposphere humidity (UTH) data from MOZAIC observations from year 2000 and later indicated a bias of UTH data towards higher RH values compared to data of the period 1994 to 1999. As a result, PDF of UTH data show a substantial fraction of observations above 100% relative humidity with respect to liquid water (RHliquid), which is not possible from thermodynamical principles. An in-depth reanalysis of the data set recovered a calibration artefact from year 2000 on, while data of the previous period from 1994 to 1999 were found to be correct. The full data set for 2000-2009 was reanalysed applying the adjusted calibration procedure. Applied correction schemes and a revised error analysis are presented along with the reanalysed PDF of RHliquid and RHice.

  11. Air temperature and humidity diversity in the Hornsund fjord area (Spitsbergen) in the period 1 July 2014 - 30 June 2015

    NASA Astrophysics Data System (ADS)

    Przybylak, Rajmund; Araźny, Andrzej; Wyszyński, Przemysław; Budzik, Tomasz; Wawrzyniak, Tomasz

    2016-04-01

    The article presents preliminary results of studies into the spatial diversity of air temperature and relative humidity (overground layer, 2 m a.g.l.) in the area of the Hornsund fjord (S Spitsbergen, approx. 77°N), based on data collected between 1 July 2014 and 30 June 2015. The Hornsund fjord runs latitudinal along approx. 40 km and its average width is about 10 km. Numerous glaciers flow into the fjord and the mountain ridges around it often exceed 700 m a.s.l. Data series obtained from 11 sites equipped with automatic weather stations (Vaisala, Campbell, Davis) or HOBO temperature and humidity sensors were used. Two sites (Hornsund HOR and the Hans Glacier HG4) have been operating for years, whereas 9 new ones (Bogstranda BOG, Fugleberget FUG, Gnålodden GNA, Gåshamnoyra GAS, Hyttevika HYT, Lisbetdalen LIS, Ostrogradskijfjella OST, Treskelodden TRE and Wilczekodden WIL) were established within the Polish-Norwegian AWAKE-2 project. Three of the sites (BOG, GAS and OST) were damaged by polar bears, hence their measurement series are shorter. A substantial spatial diversity was found in the air temperature and relative humidity in the area, mostly influenced by elevation, type of surface and distance from the Greenland Sea's open water. During the year (July 2014 - June 2015), the areas of HYT (-1.1°C) and WIL (-1.9°C) were the warmest. Both sites are located on the west coast of the fjord. The HYT demonstrates the most favourable temperature conditions, being orographically sheltered from the east and its cold and dry air masses. The coldest sites were the mountain-top site of FUG (-5.9°C) and the glacier-located HG4 (-4.3°C). The low temperature at FUG resulted from its elevation (568 m a.s.l.), whereas at HG4 (184 m a.s.l) the glaciated surface also added up to the result. In the analysed period, the annual course of air temperature in the area had a clear minimum in February, when the lowest mean monthly values ranged from -9.4°C at HYT to -15.1°C at

  12. Post Civil War African American History: Brief Periods of Triumph, and Then Despair.

    PubMed

    Graff, Gilda

    2016-01-01

    During Reconstruction, which is often called the most progressive period in American history, African Americans made great strides. By 1868 African American men constituted a majority of registered voters in South Carolina and Mississippi, and by 1870 eighty-five percent of Mississippi's black jurors could read and write. However, Reconstruction was followed by approximately one hundred years of Jim Crow laws, lynching, disenfranchisement, sharecropping, unequal educational resources, terrorism, racial caricatures, and convict leasing. The Civil Rights Revolution finally ended that period of despair, but the era of mass incarceration can be understood as a reaction to the Civil Rights Movement. This article attempts to understand the persistence of racism in the United States from slavery's end until the present. PMID:27108470

  13. Forecast Change in Dry and Humid Periods in South America, Using the CORDEX RCM-SMHI with Bias Correction

    NASA Astrophysics Data System (ADS)

    Giraldo Osorio, J. D.

    2015-12-01

    Extreme precipitation events will be more common in the future due to climate change. In this work, precipitation deviations were computed using the Standardized Precipitation Index (SPI), which is broadly recognized because its simplicity. The SPI associates the precipitation data with standardized deviations, so long series are required to fit the distribution, then transformed into a standard normal variable. The SPI positive values point out precipitation surpluses, while negative values show precipitation deficits. Monthly precipitation data from Delaware University (UDATP), and the Swedish Meteorological and Hydrological Institute Regional Climate Model (SMHI-RCM), were used. Both databases cover South America with 0.5° spatial resolution, and they have a shared temporary window between 1951-2005. The forecast time window of SMHI-RCM spans between 2006-2100, and the chosen Representative Concentration Pathway is the RCP-4.5. Prior to calculation of SPI12 (12 months-SPI), a bias correction of RCM precipitation data was done, using the period 1961-1990 as reference. The same period was used as reference for the SPI12; in this way, the forecasted values of SPI12 were compared with those computed between 1961-1990. The appended figure shows the predicted changes in dry and humid spells in South America. The computed values in the reference period 1961-1990, the forecast period 2071-2100, and the change between them are presented for a) yearly average precipitation, b) number of months with SPI12<-1, and c) number of months with SPI12<+1. According to forecast, a rise of the number of dry periods are expected in Chile, the Gran Chaco region, the Andean mountain range in Peru, Ecuador and Colombia, and the Amazonian forest between Peru and Colombia. On the other hand, a rise of the number of surplus periods are expected in northeast Brazil, and the Caribbean Sea coast of the continent. This analysis is concordant with the RCM-SMHI forecast of precipitation trends.

  14. Consensus Sequence of 27 African Horse Sickness Virus Genomes from Viruses Collected over a 76-Year Period (1933 to 2009)

    PubMed Central

    Wright, Isabella M.; van Dijk, Alberdina A.

    2015-01-01

    We announce the complete consensus genome sequence of 27 African horse sickness viruses, representing all nine African horse sickness virus (AHSV) serotypes from historical and recent isolates collected over a 76-year period (1933 to 2009). The data set includes the sequence of the virulent Office International des Epizooties AHSV reference strains which are not adapted to cell culture. PMID:26358586

  15. Multiple Criteria and Multiple Periods Performance Analysis: The Comparison of North African Railways

    NASA Astrophysics Data System (ADS)

    Sabri, Karim; Colson, Gérard E.; Mbangala, Augustin M.

    2008-10-01

    Multi-period differences of technical and financial performances are analysed by comparing five North African railways over the period (1990-2004). A first approach is based on the Malmquist DEA TFP index for measuring the total factors productivity change, decomposed into technical efficiency change and technological changes. A multiple criteria analysis is also performed using the PROMETHEE II method and the software ARGOS. These methods provide complementary detailed information, especially by discriminating the technological and management progresses by Malmquist and the two dimensions of performance by Promethee: that are the service to the community and the enterprises performances, often in conflict.

  16. Germination of Fusarium graminearum Ascospores and Wheat Infection are Affected by Dry Periods and by Temperature and Humidity During Dry Periods.

    PubMed

    Manstretta, V; Morcia, C; Terzi, V; Rossi, V

    2016-03-01

    The effects of temperature and relative humidity (RH) on germination of Fusarium graminearum ascospores, and of dry periods (DP) of different lengths and of temperature and RH during DP on ascospore survival were studied both in vitro and in planta. Optimal temperatures for ascospore germination at 100% RH were 20 and 25°C; germination was ≤5% when ascospores were incubated at 20°C and RH ≤ 93.5%. Viable ascospores were found at all tested combinations of DP duration (0 to 48 h) × temperature (5 to 40°C) or RH (32.5 to 100% RH). Germination declined as DP duration and temperature increased. Germination was lower for ascospores kept at 65.5% RH during the DP than at 76.0, 32.5, or 93.5% RH. Equations were developed describing the relationships between ascospore germination, DP duration and temperature or RH during DP. Durum wheat spikes were inoculated with ascospores and kept dry for 0 to 48 h at approximately 15°C and 65% RH; plants were then kept in saturated atmosphere for 48 h to favor infection. Fungal biomass, measured as F. graminearum DNA by quantitative polymerase chain reaction, declined as DP increased to 24 and 48 h at 3 and 9 days postinfection but not in spikes at maturity. PMID:26623994

  17. Timing of vegetation changes at the end of the Holocene Humid Period in desert areas at the northern edge of the Atlantic and Indian monsoon systems

    NASA Astrophysics Data System (ADS)

    Lézine, Anne-Marie

    2009-08-01

    This article aims at discussing the ecological response of the terrestrial and fresh water dependant environments to the installation of arid conditions at the end of the Holocene Humid Period in the Atlantic and Indian monsoon domains. It is mainly focused on dry environments from Chad, Oman and Pakistan where new, high-resolution pollen sequences have been provided. Pollen data show that local hydrological conditions have played a major role in the destruction or survival of tropical tree populations at the end of the Holocene Humid Period, as well as partly explaining the asynchronous pattern of recorded environmental changes in most tropical regions. In desert areas, the response of the fresh water dependant systems to the shift from humid to arid climate conditions appears to have followed a threshold-like pattern. In contrast, terrestrial ecosystems have gradually adapted to increased drought, as shown by the progressive decrease of tropical tree species at Yoa or the gradual expansion in dry plant types in Oman and Pakistan from 6000 cal yrs BP to the present. A remarkable synchroneity in environmental change is recorded at the northern edge of the Atlantic and Indian monsoon systems, with the extreme end of the Holocene Humid Period corresponding to the last occurrence of tropical trees in the desert and the last record of prolonged SW monsoon rainfall over north-western Asia around 4700-4500 cal yrs BP.

  18. Comparison of Abuse Experiences of Rural and Urban African American Women During Perinatal Period

    PubMed Central

    Bhandari, Shreya; Bullock, Linda F. C.; Richardson, Jeanita W.; Kimeto, Pamela; Campbell, Jacquelyn C.; Sharps, Phyllis W.

    2015-01-01

    A subsample of 12 African American women (6 urban and 6 rural) were selected from a larger longitudinal, randomized control trial, Domestic Violence Enhanced Home Visitation (DOVE-R01 900903 National Institute of Nursing Research [NINR]/National Institutes of Health [NIH]). All African American women were chosen to control for any racial- and/or race-related cultural differences that may exist among women across geographical areas. The experiences of abuse during the perinatal period are drawn from in-depth interviews conducted at five points in time during pregnancy and the post-partum period. The analysis describes three major themes that highlight the similarities and differences among rural and urban women. The main themes found were (1) types of abuse, (2) location of abuse, and (3) response to abuse. In addition, two sub-themes (a) defiance and compliance and (b) role of children were also identified. Implications for universal screening for women of reproductive age, safer gun laws, and the need for further research are discussed. PMID:25315478

  19. Comparison of abuse experiences of rural and urban African American women during perinatal period.

    PubMed

    Bhandari, Shreya; Bullock, Linda F C; Richardson, Jeanita W; Kimeto, Pamela; Campbell, Jacquelyn C; Sharps, Phyllis W

    2015-07-01

    A subsample of 12 African American women (6 urban and 6 rural) were selected from a larger longitudinal, randomized control trial, Domestic Violence Enhanced Home Visitation (DOVE-R01 900903 National Institute of Nursing Research [NINR]/National Institutes of Health [NIH]). All African American women were chosen to control for any racial- and/or race-related cultural differences that may exist among women across geographical areas. The experiences of abuse during the perinatal period are drawn from in-depth interviews conducted at five points in time during pregnancy and the post-partum period. The analysis describes three major themes that highlight the similarities and differences among rural and urban women. The main themes found were (1) types of abuse, (2) location of abuse, and (3) response to abuse. In addition, two sub-themes (a) defiance and compliance and (b) role of children were also identified. Implications for universal screening for women of reproductive age, safer gun laws, and the need for further research are discussed. PMID:25315478

  20. South Africans' experiences of being old and of care and caring in a transitional period.

    PubMed

    Bohman, Doris M; van Wyk, Neltjie C; Ekman, Sirkka-Liisa

    2011-09-01

    This focused ethnographic study aimed to illuminate a group of South Africans' experiences of being old and of care and caring in a transitional period. With a growing number of older people in Africa, studies on the individual experiences may help to develop care which is more sensitively based on the needs for older people in a changing Southern Africa context. Data were collected through group and individual in-depth interviews and participant observations which involved 16 individuals, aged 52-76. Data were analysed using a qualitative content analysis. The study showed two interrelated themes reflections on life and ubuntu - an orientation towards others. Findings were discussed from the viewpoint of the theory of gerotranscendence, showing similarities as well as differences, possibly due to societal and cultural differences. Shortage of formal care for older people living in poor conditions in Southern Africa, gave rise to the discussion for the need of a contextualized development of gerontological care. To enhance knowledge on the theory of gerotranscendence and develop guidelines for nursing in home-based care/community-based care in a South African context may be a first step to support older people in their process towards gerotranscendence. PMID:21631870

  1. High-sensitivity metal oxides-coated long-period fiber grating sensors for humidity monitoring in high-energy physics applications

    NASA Astrophysics Data System (ADS)

    Berruti, G.; Consales, M.; Borriello, Anna; Giordano, M.; Buontempo, S.; Breglio, Giovanni; Makovec, A.; Petagna, Paolo; Cusano, A.

    2014-05-01

    This contribution deals with a feasibility analysis for the development of radiation tolerant fiber optic humidity sensors based on long period grating (LPG) technology to be applied in high-energy physics (HEP) experiments currently running at the European Organization for Nuclear Research (CERN). In particular, here we propose a high-sensitivity LPG sensor coated with a finely tuned titanium dioxide (TiO2) thin layer (~100 nm thick) through the sol gel deposition method. The sensor characterization in the relative humidity (RH) range [0-75] % at four different temperatures (in the range -10°C - 25°C) was carried out to assess sensor performances in real operative conditions required in typical experiments running at CERN. Experimental results demonstrate the very high RH sensitivities of the proposed device (up to 1.4 nm/%RH in correspondence of very low humidity levels), which turned out to be from one to three orders of magnitudes higher than those exhibited by fiber Bragg grating (FBG) sensors coated with micrometer thin polyimide overlays. The radiation tolerance capability of the TiO2-coated LPG sensor is also investigated by comparing the sensing performances before and after its exposure to 1Mrad dose of γ-ionizing radiation. Collected results demonstrate the strong potentialities of the proposed technology in light of its future exploitation in HEP applications as robust and valid alternative to currently used commercial hygrometers.

  2. The palaeoclimatic significance of Eurasian Giant Salamanders (Cryptobranchidae: Zaissanurus, Andrias) - indications for elevated humidity in Central Asia during global warm periods (Eocene, late Oligocene warming, Miocene Climate Optimum)

    NASA Astrophysics Data System (ADS)

    Vasilyan, Davit; Böhme, Madelaine; Winklhofer, Michael

    2010-05-01

    Cryptobranchids represent a group of large sized (up to 1.8 m) tailed amphibians known since the Middle Jurassic (Gao & Shubin 2003). Two species are living today in eastern Eurasia: Andrias davidianus (China) and A. japonicus (Japan). Cenozoic Eurasian fossil giant salamanders are known with two genera and two or three species from over 30 localities, ranging from the Late Eocene to the Early Pliocene (Böhme & Ilg 2003). The Late Eocene species Zaissanurus beliajevae is restricted to the Central Asian Zaissan Basin (SE-Kazakhstan, 50°N, 85°E), whereas the Late Oligocene to Early Pliocene species Andrias scheuchzeri is distributed from Central Europe to the Zaissan Basin. In the latter basin the species occur during two periods; the latest Oligocene and the late Early to early Middle Miocene (Chkhikvadse 1982). Andrias scheuchzeri is osteological indistinguishable from both recent species, indicating a similar ecology (Westfahl 1958). To investigate the palaeoclimatic significance of giant salamanders we analyzed the climate within the present-day distribution area and at selected fossil localities with independent palaeoclimate record. Our results indicate that fossil and recent Andrias species occur in humid areas where the mean annual precipitation reach over 900 mm (900 - 1.300 mm). As a working hypothesis (assuming a similar ecology of Andrias and Zaissanurus) we interpret occurrences of both fossil Eurasian giant salamanders as indicative for humid palaeoclimatic conditions. Based on this assumption the Late Eocene, the latest Oligocene (late Oligocene warming) and the late Early to early Middle Miocene (Miocene Climatic Optimum) of Central Asia (Zaissan Basin) are periods of elevated humidity, suggesting a direct (positive) relationship between global climate and Central Asian humidity evolution. Böhme M., Ilg A. 2003: fosFARbase, www.wahre-staerke.com/ Chkhikvadze V.M. 1982. On the finding of fossil Cryptobranchidae in the USSR and Mongolia. Vertebrata

  3. Circadian rhythm phase shifts and endogenous free-running circadian period differ between African-Americans and European-Americans

    PubMed Central

    Eastman, Charmane I.; Suh, Christina; Tomaka, Victoria A.; Crowley, Stephanie J.

    2015-01-01

    Successful adaptation to modern civilization requires the internal circadian clock to make large phase shifts in response to circumstances (e.g., jet travel and shift work) that were not encountered during most of our evolution. We found that the magnitude and direction of the circadian clock's phase shift after the light/dark and sleep/wake/meal schedule was phase-advanced (made earlier) by 9 hours differed in European-Americans compared to African-Americans. European-Americans had larger phase shifts, but were more likely to phase-delay after the 9-hour advance (to phase shift in the wrong direction). The magnitude and direction of the phase shift was related to the free-running circadian period, and European-Americans had a longer circadian period than African-Americans. Circadian period was related to the percent Sub-Saharan African and European ancestry from DNA samples. We speculate that a short circadian period was advantageous during our evolution in Africa and lengthened with northern migrations out of Africa. The differences in circadian rhythms remaining today are relevant for understanding and treating the modern circadian-rhythm-based disorders which are due to a misalignment between the internal circadian rhythms and the times for sleep, work, school and meals. PMID:25670162

  4. Nanofilm-coated long-period fiber grating humidity sensors for corrosion detection in structural health monitoring

    NASA Astrophysics Data System (ADS)

    Zheng, Shijie; Zhu, Yinian; Krishnaswamy, Sridhar

    2011-04-01

    Long-period gratings (LPGs) have shown their significant promising applications in sensors owing to the attractive features that they posses such as small size, immunity for electromagnetic interference, geometric versatility, multiplexing capability, and resistance to corrosive and hazardous environments. Recent researches have revealed that LPGs written on the standard optical fibers could be used as a powerful sensing platform for structural health monitoring. In this work, we inscribe LPGs into SMF-28 optical fiber by focused-beam CO2 laser, demonstrating as a refractive index sensor for nondestructive chemical detections in the civil infrastructures. Although evanescent-field based LPG sensors have been applied in quantitatively monitoring chemical analytes including moisture, chloride, and corrosion by-product, etc., the sensitivity, selectivity, and response time as well as thermo-stability of such sensors are still the issues for some special purposes. In order to improve those characteristics of the sensors, we propose two types of nano-film to be coated in grating region by electrostatic self-assembly (ESA) deposition processing. The primary coating does not affect on LPG transmission parameters such as resonance wavelength and its intensity that can be used for sensing, but it increases the sensitivity to refractive index change of surrounding material. The secondary coating is for selectively absorption of analyte molecule of interest. Response time of the nanofilm-coated LPG sensor is dependent on the analyte absorption and de-absorption rates as well as the thicknesses of the coating materials, which is also investigated. Multi-channel sensor system is being designed to monitor different analytes simultaneously, which is continuing to further explore the monitoring of structural health conditions through in situ measurements of corrosion in the concrete structures.

  5. EDITORIAL: Humidity sensors Humidity sensors

    NASA Astrophysics Data System (ADS)

    Regtien, Paul P. L.

    2012-01-01

    All matter is more or less hygroscopic. The moisture content varies with vapour concentration of the surrounding air and, as a consequence, most material properties change with humidity. Mechanical and thermal properties of many materials, such as the tensile strength of adhesives, stiffness of plastics, stoutness of building and packaging materials or the thermal resistivity of isolation materials, all decrease with increasing environmental humidity or cyclic humidity changes. The presence of water vapour may have a detrimental influence on many electrical constructions and systems exposed to humid air, from high-power systems to microcircuits. Water vapour penetrates through coatings, cable insulations and integrated-circuit packages, exerting a fatal influence on the performance of the enclosed systems. For these and many other applications, knowledge of the relationship between moisture content or humidity and material properties or system behaviour is indispensable. This requires hygrometers for process control or test and calibration chambers with high accuracy in the appropriate temperature and humidity range. Humidity measurement methods can roughly be categorized into four groups: water vapour removal (the mass before and after removal is measured); saturation (the air is brought to saturation and the `effort' to reach that state is measured); humidity-dependent parameters (measurement of properties of humid air with a known relation between a specific property and the vapour content, for instance the refractive index, electromagnetic spectrum and acoustic velocity); and absorption (based on the known relation between characteristic properties of non-hydrophobic materials and the amount of absorbed water from the gas to which these materials are exposed). The many basic principles to measure air humidity are described in, for instance, the extensive compilations by Wexler [1] and Sonntag [2]. Absorption-type hygrometers have small dimensions and can be

  6. The early Holocene humid period in the Tayma palaeolake, NW Arabian Peninsula -- A high-resolution micro-facies and geochemical approach

    NASA Astrophysics Data System (ADS)

    Neugebauer, Ina; Plessen, Birgit; Dinies, Michèle; Engel, Max; Tjallingii, Rik; Brauer, Achim

    2016-04-01

    The Tayma palaeolake is a rare archive of the early Holocene humid period in northern Arabia (Dinies et al. 2015; Engel et al. 2012). Here we present a ca. 1 m thick and 500 years spanning annually laminated sediment section that was deposited in the centre of the former lake from ca. 8500 to 8000 calibrated years (cal. yrs) BP, as determined by AMS 14C dating of pollen concentrates (Dinies et al. 2015). High-resolution micro-facies analyses based on thin section microscopy, μXRF element scanning, δ18Ocarb and δ13Ccarb measurements on single carbonate laminae, as well as geochemical measurements on bulk samples for TOC, CaCO3, C/N ratio, δ18Ocarb, δ13Ccarb, δ13Corg and δ15N determination were performed in order to investigate the sedimentological and geochemical changes along the varved sequence in great detail. The finely laminated marl sediments are mainly composed of sub-mm thick laminae of endogenic aragonite, organic matter and diatoms, as well as occasional, often graded silt-clay layers. Following an early lake phase from ca. 8700 to 8500 cal. yrs BP characterized by coarsely laminated, presumably non-annual marl sediments that are rich in ostracods, three main varved phases can be distinguished within the investigated section: (1) aragonitic-organic varves from ca. 8500 to 8300 cal. yrs BP, (2) diatom-organic varves from ca. 8300 to 8100 cal. yrs BP that frequently include aragonite laminae and occasionally gastropod and ostracod shells, and (3) organic varves from ca. 8100 to 8000 cal. yrs BP with decreasing diatom and aragonite laminae and an increasing frequency of gypsum layers. After this period, gypsum becomes abundant and fine lamination appears only sporadically. In addition, we observe increasing trends of TOC, C/N and δ13Ccarb and decreasing δ18Ocarb during phase 1 and excess δ18Ocarb, δ13Ccarb and TOC values during phase 2, pointing towards the maximum lake productivity and increased seasonal precipitation. We interpret this

  7. Identification of a Pertinent Referential Period for Drought Definition in the West African Soudano-Sahelian Zone from Precipitation

    NASA Astrophysics Data System (ADS)

    Ibrahim, B.; Wisser, D.; Barry, B.

    2014-12-01

    Many studies have been undertaken on climate variability analysis in West Africa since the drastic drought recorded at the beginning of the 1970s. The variability highlighted by these studies relies in many cases on different baseline periods chosen with regard to the data available or to the reference periods defined by the World Meteorological Organization (WMO). However, the significance of the change in a time series for a given period is determined from some statistical tests. We develop in this study a statistical method to identify a pertinent reference period for rainfall and temperature variability analysis in the West African Soudano-Sahelian zone. The method is based on an application of three tests of homogeneity in time series and three tests of shift detection in time series. The pertinent reference period is defined as a period of more than 20 years and homogeneous with regard to the main climate parameters (rainfall and temperature). The application of the method on four different gridded climate data from 1901 to 2012 shows that the 1945-1970 period is the longest homogeneous period with regard to the annual rainfall amount. An assessment of the significance of the difference between the confidence interval at the level of 95% around the average during this period and the annual rainfall amounts time series shows that the normal amount is between -10% and +10% of that average. Thus, with regard to that referential period, a wet (dry) year is defined with a surplus (gap) of 10% in the annual rainfall amount above (below) this average. The decadal proportions of wet and dry years reveal that the 1971-1980 period presents the most important number of significant dry years with 1984 as the driest year over the whole 1901-2012 period. The drought periods recorded in the region are mainly characterized by segments of consecutive dry years that had severe impacts on crop production and livestock. Key words: climate variability; climate change; drought

  8. Impacts of dust reduction on the northward expansion of the African monsoon during the Green Sahara period

    NASA Astrophysics Data System (ADS)

    Pausata, Francesco S. R.; Messori, Gabriele; Zhang, Qiong

    2016-01-01

    The West African Monsoon (WAM) is crucial for the socio-economic stability of millions of people living in the Sahel. Severe droughts have ravaged the region in the last three decades of the 20th century, highlighting the need for a better understanding of the WAM dynamics. One of the most dramatic changes in the West African Monsoon (WAM) occurred between 15000-5000 yr BP, when increased summer rainfall led to the so-called "Green Sahara" and to a reduction in dust emissions from the region. However, model experiments are unable to fully reproduce the intensification and geographical expansion of the WAM during this period, even when vegetation over the Sahara is considered. Here, we use a fully coupled simulation for 6000 yr BP (Mid-Holocene) in which prescribed Saharan vegetation and dust concentrations are changed in turn. A closer agreement with proxy records is obtained only when both the Saharan vegetation changes and dust decrease are taken into account. The dust reduction strengthens the vegetation-albedo feedback, extending the monsoon's northern limit approximately 500 km further than the vegetation-change case only. We therefore conclude that accounting for changes in Saharan dust loadings is essential for improving model simulations of the WAM during the Mid-Holocene.

  9. Lightning fatalities on the South African Highveld: a retrospective descriptive study for the period 1997 to 2000.

    PubMed

    Blumenthal, Ryan

    2005-03-01

    A review of the Southern Africa medical literature shows a paucity of published data regarding lightning fatalities. The South African Highveld has a lightning ground flash density of 6 to 9 flashes/km/year, with a high incidence of thunderstorm days per year (some 40-70). The Highveld has a largely urban population, many of whom have low socioeconomic status and poor education, housing, and other infrastructures and hence (possibly) are at greater exposure risk. Thirty-eight victims of lightning-related death were identified from the records of the 6 large medicolegal mortuaries on the South African Highveld, serving a population of approximately 7 million, for the period 1997 to 2000. Analysis of the records revealed that 95% of all victims were black, 79% were male, and the average age was 36 years. Lightning strikes occurred from September through to April (normal summer rainfall period), and the most strikes took place in the late afternoon (3:00 pm to 6:00 pm). All except 1 case occurred outdoors. In the autopsy reports, mention was made of singeing of hair in 68% of cases, and mention of damage to clothing was made in 26% of cases. Cutaneous thermal injuries were noted in 34 of the 38 cases, with apparent electrothermal injuries of the feet noted in 4 cases. Fifty-two percent of victims sustained some form of associated blunt-force injury (including abrasions, contusions, etc). Specific keraunopathologic injuries were described in only 2 of the cases. Twenty-one cases had some form of internal organ injury. This study serves to illustrate the relatively high incidence of lightning strikes in the region and calls for a more systematic and detailed investigative protocol in lightning-related deaths. PMID:15725779

  10. Overview of the Dust and Biomass-burning Experiment and African Monsoon Multidisciplinary Analysis Special Observing Period-0

    NASA Astrophysics Data System (ADS)

    Haywood, J. M.; Pelon, J.; Formenti, P.; Bharmal, N.; Brooks, M.; Capes, G.; Chazette, P.; Chou, C.; Christopher, S.; Coe, H.; Cuesta, J.; Derimian, Y.; Desboeufs, K.; Greed, G.; Harrison, M.; Heese, B.; Highwood, E. J.; Johnson, B.; Mallet, M.; Marticorena, B.; Marsham, J.; Milton, S.; Myhre, G.; Osborne, S. R.; Parker, D. J.; Rajot, J.-L.; Schulz, M.; Slingo, A.; Tanré, D.; Tulet, P.

    2008-12-01

    The African Monsoon Multidisciplinary Analysis (AMMA) is a major international campaign investigating far-reaching aspects of the African monsoon, climate and the hydrological cycle. A special observing period was established for the dry season (SOP0) with a focus on aerosol and radiation measurements. SOP0 took place during January and February 2006 and involved several ground-based measurement sites across west Africa. These were augmented by aircraft measurements made by the Facility for Airborne Atmospheric Measurements (FAAM) aircraft during the Dust and Biomass-burning Experiment (DABEX), measurements from an ultralight aircraft, and dedicated modeling efforts. We provide an overview of these measurement and modeling studies together with an analysis of the meteorological conditions that determined the aerosol transport and link the results together to provide a balanced synthesis. The biomass burning aerosol was significantly more absorbing than that measured in other areas and, unlike industrial areas, the ratio of excess carbon monoxide to organic carbon was invariant, which may be owing to interaction between the organic carbon and mineral dust aerosol. The mineral dust aerosol in situ filter measurements close to Niamey reveals very little absorption, while other measurements and remote sensing inversions suggest significantly more absorption. The influence of both mineral dust and biomass burning aerosol on the radiation budget is significant throughout the period, implying that meteorological models should include their radiative effects for accurate weather forecasts and climate simulations. Generally, the operational meteorological models that simulate the production and transport of mineral dust show skill at lead times of 5 days or more. Climate models that need to accurately simulate the vertical profiles of both anthropogenic and natural aerosols to accurately represent the direct and indirect effects of aerosols appear to do a reasonable job

  11. African Monsoon Multidisciplinary Analysis (AMMA) : The Special Observing Period of 2006

    NASA Astrophysics Data System (ADS)

    Polcher, J.; Cairo, F.; Fierli, F.; Höller, H.; Law, K.; Mari, C.; Reeves, C.; Schlager, H.

    2006-12-01

    The AMMA project aims at enhancing our understanding of the West African monsoon and its underlying physical, chemical and biological processes. This enhanced knowledge of the processes involved in the establishment and variability of the monsoon will be used to improve our capacity to predict it and evaluate the impacts on land-productivity, management of water resources and public health. The objective is to provide societies in Africa with improved tools to manage their dependence on environmental conditions. In the framework of AMMA a dense observational network has been established both as routine and campaign- based facilities. The aim is to provide a complete picture of the physical, chemical and biological processes over the ocean, the continent and in the atmosphere. The base network has been established over the last few year and covers surface states and surface flux monitoring in a number catchments over the climatic gradient of the region. The upper-air sounding network was upgraded and enhanced to improve the data available for operational weather forecasting. During 2006 AMMA supported a large field campaign to cover the dry season (SOP0), the monsoon onset (SOP1) and the wet season (SOP2). The enhancement to the observing system in 2006 included balloon borne instruments, a lightning network over northern Benin, 3 research vessels and 5 research aircraft stationed in the Niamey and Ouagadougou. Most of SOP2 observations were dedicated to the intense mesoscale convective systems which are generated in the region and travel to the West. Their impact on the circulation in the troposphere and lower stratosphere, the water cycle in the region and the transport of trace gases and aerosols have been observed at different stages of the life cycle of these systems. This talk will provide a overview of the AMMA project and the observations carried out in 2006, focusing on the most relevant events.

  12. Prevalence and rates of intimate partner violence among South African women during pregnancy and the postpartum period

    PubMed Central

    Groves, Allison K.; Moodley, Dhayendre; McNaughton-Reyes, Luz; Martin, Sandra L.; Foshee, Vangie; Maman, Suzanne

    2014-01-01

    Objectives Intimate partner violence (IPV) is a significant public health problem in South Africa. However, limited research exists on IPV during pregnancy and the postpartum period in South Africa. The purpose of this study is to describe the prevalence, rates and correlates of IPV among South African women during pregnancy and the first nine months postpartum. Methods Data are from a longitudinal study with women recruited during pregnancy between 2008 and 2010 at a public clinic in Durban. We used a modified version of the World Health Organization’s IPV scale to estimate prevalence and rates of IPV during pregnancy, at four months postpartum and nine months postpartum and we used logistic regression to assess the correlates of IPV during this time. Results More than 20% of all women experienced at least one act of physical, psychological or sexual IPV during pregnancy. Nearly one-quarter of all women experienced at least one act of physical, psychological or sexual IPV during the first nine months postpartum. Psychological IPV was the most prevalent type of IPV during pregnancy and the first four months postpartum. Age and previous violence within the relationship were associated with IPV during pregnancy and IPV during the postpartum period. Conclusions The high levels of IPV during pregnancy and the postpartum period highlight the need to develop screening and intervention strategies specifically for this time. Further, women should be screened not only for physical violence but also psychological violence given that psychological violence may result in distinct negative consequences. PMID:24889116

  13. Traveling ionospheric disturbances observed at South African midlatitudes during the 29-31 October 2003 geomagnetically disturbed period

    NASA Astrophysics Data System (ADS)

    Katamzi, Zama T.; Habarulema, John Bosco

    2014-01-01

    This paper presents traveling ionospheric disturbances (TIDs) observations from GPS measurements over the South African region during the geomagnetically disturbed period of 29-31 October 2003. Two receiver arrays, which were along two distinct longitudinal sectors of about 18°-20° and 27°-28° were used in order to investigate the amplitude, periods and virtual propagation characteristics of the storm induced ionospheric disturbances. The study revealed a large sudden TEC increase on 28 October 2003, the day before the first of the two major storms studied here, that was recorded simultaneously by all the receivers used. This pre-storm enhancement was linked to an X-class solar flare, auroral/magnetospheric activities and vertical plasma drift, based on the behaviour of the geomagnetic storm and auroral indices as well as strong equatorial electrojet. Diurnal trends of the TEC and foF2 measurements revealed that the geomagnetic storm caused a negative ionospheric storm; these parameters were depleted between 29 and 31 October 2003. Large scale traveling ionospheric disturbances were observed on the days of the geomagnetic storms (29 and 31 October 2003), using line-of-sight vertical TEC (vTEC) measurements from individual satellites. Amplitude and dominant periods of these structures varied between 0.08-2.16 TECU, and 1.07-2.13 h respectively. The wave structures were observed to propagate towards the equator with velocities between 587.04 and 1635.09 m/s.

  14. Thyrotoxic hypokalemic periodic paralysis in an African male: a case report.

    PubMed

    Belayneh, Dereje K; Kellerth, Thomas

    2015-02-01

    Thyrotoxic hypokalemic periodic paralysis is a rare manifestation of thyrotoxicosis and is rarely reported in non-Asian populations. A 26-year-old Ethiopian male who presented with recurrent flaccid tetraparesis, hypokalemia, and hyperthyroidism is reported here. Thyroid function should be routinely checked in patients with acute or recurrent hypokalemic paralysis. PMID:25767707

  15. Volcanic Centers in the East African Rift: Imaging Volcanic Processes with Long-Period Event Identification and Ambient Noise Tomography

    NASA Astrophysics Data System (ADS)

    Patlan, E.; Wamalwa, A. M.; Hardy, S.; Kaip, G.; Velasco, A. A.

    2014-12-01

    Kenya actively seeks to produce geothermal energy, and the country lies within the East African Rift System (EARS). The EARS, an active continental rift zone, appears to be a developing tectonic plate boundary and thus, has a number of active as well as dormant volcanoes through its extent. These volcanic centers can be used as potential sources for geothermal energy. The University of Texas at El Paso (UTEP) and the Geothermal Development Company (GDC) began collaborating to monitor several volcanic centers, which have included passive seismic sensor deployments experiment. A number of seismological techniques will be applied to the data being collected at the four volcanic centers: Menengai, Silali, and Paka, and Korosi. In particular, we will identify long-period signals and tremor local using a time-reversal approach. Low-frequency earthquakes are interpreted as magma passing through conduits of the magma chamber and/or fluid being transported as a function of magma movement or hydrothermal activity. The time-reversal locations will help identify the margin of the volcano and caldera, and faults that could form conduits for fluids. We will also perform ambient noise tomography to image the magma chamber and the conduit feeding the volcanoes. The combination of the velocity snapshots of the magma chamber, low-frequency events, and long period events will help us interpret the activity of the calderas and volcanoes. Overall, all these techniques will help us understand magma movement and volcanic processes in the region.

  16. Humidity profiles over the ocean

    NASA Technical Reports Server (NTRS)

    Liu, W. T.; Tang, Wenqing; Niiler, Pearn P.

    1991-01-01

    The variabilities of atmospheric humidity profile over oceans from daily to interannual time scales were examined using 9 years of daily and semidaily radiosonde soundings at island stations extending from the Arctic to the South Pacific. The relative humidity profiles were found to have considerable temporal and geographic variabilities, contrary to the prevalent assumption. Principal component analysis on the profiles of specific humidity were used to examine the applicability of a relation between the surface-level humidity and the integrated water vapor; this relation has been used to estimate large-scale evaporation from satellite data. The first principal component was found to correlate almost perfectly with the integrated water vapor. The fractional variance represented by this mode increases with increasing period. It reaches approximately 90 percent at two weeks and decreases sharply, below one week, down to approximately 60 percent at the daily period. At low frequencies, the integrated water vapor appeared to be an adequate estimator of the humidity profile and the surface-level humidity. At periods shorter than a week, more than one independent estimator is needed.

  17. Functional anatomy of the lacrimal gland in African black ostrich Struthio camelus domesticus in the embryonic and postnatal period.

    PubMed

    Klećkowska-Nawrot, Joanna; Goździewska-Harłajczuk, Karolina; Nowaczyk, Renata; Krasucki, Krzysztof

    2015-01-01

    The aim of the present study was morphological and histochemical analysis of the lacrimalgland (LG) in African black ostrich Struthio camelus domesticus in the embryonic and postnatalperiod. Studies were conducted on 50 ostriches aged between the 28th day of incubation until7 months old. Tissue sections were stained with haematoxylin and eosin, Azan trichrome,periodic acid-Schiff, Alcian blue pH 2.5, aldehyde fuchsin and Hale's dialysed iron. The LGin ostrich was classified as a tubulo-acinar type. The primordia of the lobes were determinedin the LG structure on the 28th day of incubation, whilst the weakly visible lobes with aciniand tubules were observed on the 40th day of incubation. Morphometric studies of the LGshowed steady growth, characterised by an increase in both length and width. Histometricmeasurements of lobe size showed little difference between the first, second and third agegroups, whilst in the fourth age group a marked increase in size of lobes was observed.The study showed that, apart from morphological changes, during the growth of the LGthe character of acid mucopolysaccharides changed. Sulphated acid mucopolysaccharideswere indicated, particularly with aldehyde fuchsin (AF) staining in the fourth age group.The Hale's dialysed iron (HDI) staining showed a low concentration of carboxylated acidmucopolysaccharides in the first and second age groups and a higher concentration in thethird and fourth age groups. Periodic acid-Schiff staining (PAS)-positive cells were observedin each age group, but only a small number of cells with a weakly PAS-positive reaction weredemonstrated in the first age group. PMID:26017903

  18. Astronomically forced variations in western African rainfall (21°N-20°S) during the Last Interglacial period

    NASA Astrophysics Data System (ADS)

    Govin, Aline; Varma, Vidya; Prange, Matthias

    2014-03-01

    This study documents the long-term evolution of western African precipitation during the Last Interglacial (LIG). We compare geochemical records obtained on nine sediment cores from the western African margin to a transient simulation (130-115 ka) performed with an ocean-atmosphere general circulation model and insolation as sole forcing. Good agreement between proxy records and model outputs indicates that long-term changes in western African precipitation largely responded to insolation variations during most of the LIG. After an early LIG dry phase (related to high-latitude iceberg melting or dating uncertainties), boreal summer insolation controlled the intensification of the North African monsoon between 127 and 122 ka, perhaps facilitating human migrations out of Africa. Equatorial African rainfall slightly increased throughout the LIG in response to increasing annual insolation. East-west contrasting rainfall evolutions at 10-20°S illustrate the complex southern African response, in contrast to more direct responses of North and equatorial western Africa, to insolation forcing.

  19. Dwarf nova oscillations and quasi-periodic oscillations in cataclysmic variables - VIII. VW Hyi in outburst observed with the Southern African Large Telescope

    NASA Astrophysics Data System (ADS)

    Woudt, P. A.; Warner, B.; O'Donoghue, D.; Buckley, D. A. H.; Still, M.; Romero-Colemero, E.; Väisänen, P.

    2010-01-01

    We analyse four light curves obtained at high time resolution (~0.1s) with the 11-m Southern African Large Telescope, at the ends of two normal outbursts and one superoutburst of the dwarf nova VW Hyi. All of these contain at least some Dwarf Nova Oscillations (DNOs), which, when at their highest amplitudes, are seen in unprecedented detail. In addition to the expected DNOs with periods >20 s, we find a previously unknown modulation at 13.39s, but none at shorter periods. The various DNOs and their interaction with the longer period quasi-periodic oscillations are interpreted in terms of the model of magnetically controlled flow from an accretion disc proposed earlier in this series of papers. Our observations include rare DNOs very late in outburst; we find that the fundamental period does not increase beyond ~90 s, which is the same value that the independent `longer period DNOs' converge on. Based on observations made with the Southern African Large Telescope (SALT). E-mail: Patrick.Woudt@uct.ac.za

  20. Selection of pea genotypes with partial resistance to Sclerotinia sclerotiorum across a wide range of temperatures and periods of high relative humidity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pea genotypes from the Pisum Core Collection with potential partial resistance to Sclerotinia sclerotiorum based on lesion expansion, nodal resistance and non-infection period (NIP) were assessed in growth chambers when plants were inoculated with S. sclerotiorum and incubated at five temperatures (...

  1. Measuring Relative Humidity.

    ERIC Educational Resources Information Center

    Pinkham, Chester A.; Barrett, Kristin Burrows

    1992-01-01

    Describes four experiments that enable students to explore the phenomena of evaporation and condensation and determine the relative humidity by measuring air temperature and dew point on warm September days. Provides tables to calculate saturation points and relative humidity. (MDH)

  2. [Alchemists' humid radical].

    PubMed

    Lafont, Olivier

    2007-01-01

    The term radical has been used by chemists since the beginnings and even when they still were alchemists. The term "humid radical" is present in numerous alchemists' texts. It was used to represent a kind of "humid", which was considered as different from what is nowadays called "humid", but was a sort of principle necessary for life. PMID:17575839

  3. Photogated humidity-driven motility

    NASA Astrophysics Data System (ADS)

    Zhang, Lidong; Liang, Haoran; Jacob, Jolly; Naumov, Panče

    2015-06-01

    Hygroinduced motion is a fundamental process of energy conversion that is essential for applications that require contactless actuation in response to the day-night rhythm of atmospheric humidity. Here we demonstrate that mechanical bistability caused by rapid and anisotropic adsorption and desorption of water vapour by a flexible dynamic element that harnesses the chemical potential across very small humidity gradients for perpetual motion can be effectively modulated with light. A mechanically robust material capable of rapid exchange of water with the surroundings is prepared that undergoes swift locomotion in effect to periodic shape reconfiguration with turnover frequency of <150 min-1. The element can lift objects ~85 times heavier and can transport cargos ~20 times heavier than itself. Having an azobenzene-containing conjugate as a photoactive dopant, this entirely humidity-driven self-actuation can be controlled remotely with ultraviolet light, thus setting a platform for next-generation smart biomimetic hybrids.

  4. Photogated humidity-driven motility

    PubMed Central

    Zhang, Lidong; Liang, Haoran; Jacob, Jolly; Naumov, Panče

    2015-01-01

    Hygroinduced motion is a fundamental process of energy conversion that is essential for applications that require contactless actuation in response to the day–night rhythm of atmospheric humidity. Here we demonstrate that mechanical bistability caused by rapid and anisotropic adsorption and desorption of water vapour by a flexible dynamic element that harnesses the chemical potential across very small humidity gradients for perpetual motion can be effectively modulated with light. A mechanically robust material capable of rapid exchange of water with the surroundings is prepared that undergoes swift locomotion in effect to periodic shape reconfiguration with turnover frequency of <150 min−1. The element can lift objects ∼85 times heavier and can transport cargos ∼20 times heavier than itself. Having an azobenzene-containing conjugate as a photoactive dopant, this entirely humidity-driven self-actuation can be controlled remotely with ultraviolet light, thus setting a platform for next-generation smart biomimetic hybrids. PMID:26067649

  5. African Easterly Waves in 30-day High-Resolution Global Simulations: A Case Study During the 2006 NAMMA Period

    NASA Technical Reports Server (NTRS)

    Shen, Bo-Wen; Tao, Wei-Kuo; Wu, Man-Li C.

    2010-01-01

    In this study, extended -range (30 -day) high-resolution simulations with the NASA global mesoscale model are conducted to simulate the initiation and propagation of six consecutive African easterly waves (AEWs) from late August to September 2006 and their association with hurricane formation. It is shown that the statistical characteristics of individual AEWs are realistically simulated with larger errors in the 5th and 6th AEWs. Remarkable simulations of a mean African easterly jet (AEJ) are also obtained. Nine additional 30 -day experiments suggest that although land surface processes might contribute to the predictability of the AEJ and AEWs, the initiation and detailed evolution of AEWs still depend on the accurate representation of dynamic and land surface initial conditions and their time -varying nonlinear interactions. Of interest is the potential to extend the lead time for predicting hurricane formation (e.g., a lead time of up to 22 days) as the 4th AEW is realistically simulated.

  6. The role of the South African Veterinary Council, with special reference to the period 1982-2011.

    PubMed

    Ardington, Peter C; Bigalke, Rudolph D

    2014-01-01

    The current South African Veterinary Council (SAVC) has a long and laborious history associated with the legislation responsible for its establishment. The forerunner of the SAVC, the South African Veterinary Board, was established in terms of the Veterinary Act 1933 (Act No. 16 of 1933), which was launched through Parliament as a private motion by Dr Hjalmar Reitz M.P. After several amendments, the Act was replaced with the Veterinary and Para-veterinary Professions Act 1982 (Act No. 19 of 1982), superseding the existing Board with the SAVC. One of the reasons for replacing this Act was to comply with Government policy for professional statutory bodies to become self-funding, with fees paid by registered professionals, and to constitute councils that were more representative of the profession. Apart from providing some background information, this article was virtually entirely confined to some historic aspects of the SAVC, using, as its basis, the main developments that occurred during the terms of office of its various presidents, serving from 1982 to 2011. The presidents concerned are: Prof. B.C. Jansen (28 March 1983 - 28 March 1986), Dr G.E. Frost (14 April 1986 - 31 March 1992), Prof. R.I. Coubrough (07 April 1992 - 21 March 1994), Dr P.C. Ardington (21 March 1994 - 31 March 1998), Prof H.M. Terblanche (31 March 1998 - 31 March 2004), Prof. S.S. van den Berg (01 April 2004 - 30 July 2007) and Dr R. Moerane (06 August 2007 - 31 July 2013). PMID:25686157

  7. West African monsoon dynamics inferred from abrupt fluctuations of Lake Mega-Chad

    PubMed Central

    Armitage, Simon J.; Bristow, Charlie S.; Drake, Nick A.

    2015-01-01

    From the deglacial period to the mid-Holocene, North Africa was characterized by much wetter conditions than today. The broad timing of this period, termed the African Humid Period, is well known. However, the rapidity of the onset and termination of the African Humid Period are contested, with strong evidence for both abrupt and gradual change. We use optically stimulated luminescence dating of dunes, shorelines, and fluviolacustrine deposits to reconstruct the fluctuations of Lake Mega-Chad, which was the largest pluvial lake in Africa. Humid conditions first occur at ∼15 ka, and by 11.5 ka, Lake Mega-Chad had reached a highstand, which persisted until 5.0 ka. Lake levels fell rapidly at ∼5 ka, indicating abrupt aridification across the entire Lake Mega-Chad Basin. This record provides strong terrestrial evidence that the African Humid Period ended abruptly, supporting the hypothesis that the African monsoon responds to insolation forcing in a markedly nonlinear manner. In addition, Lake Mega-Chad exerts strong control on global biogeochemical cycles because the northern (Bodélé) basin is currently the world’s greatest single dust source and possibly an important source of limiting nutrients for both the Amazon Basin and equatorial Atlantic. However, we demonstrate that the final desiccation of the Bodélé Basin occurred around 1 ka. Consequently, the present-day mode and scale of dust production from the Bodélé Basin cannot have occurred before 1 ka, suggesting that its role in fertilizing marine and terrestrial ecosystems is either overstated or geologically recent. PMID:26124133

  8. West African monsoon dynamics inferred from abrupt fluctuations of Lake Mega-Chad.

    PubMed

    Armitage, Simon J; Bristow, Charlie S; Drake, Nick A

    2015-07-14

    From the deglacial period to the mid-Holocene, North Africa was characterized by much wetter conditions than today. The broad timing of this period, termed the African Humid Period, is well known. However, the rapidity of the onset and termination of the African Humid Period are contested, with strong evidence for both abrupt and gradual change. We use optically stimulated luminescence dating of dunes, shorelines, and fluviolacustrine deposits to reconstruct the fluctuations of Lake Mega-Chad, which was the largest pluvial lake in Africa. Humid conditions first occur at ∼ 15 ka, and by 11.5 ka, Lake Mega-Chad had reached a highstand, which persisted until 5.0 ka. Lake levels fell rapidly at ∼ 5 ka, indicating abrupt aridification across the entire Lake Mega-Chad Basin. This record provides strong terrestrial evidence that the African Humid Period ended abruptly, supporting the hypothesis that the African monsoon responds to insolation forcing in a markedly nonlinear manner. In addition, Lake Mega-Chad exerts strong control on global biogeochemical cycles because the northern (Bodélé) basin is currently the world's greatest single dust source and possibly an important source of limiting nutrients for both the Amazon Basin and equatorial Atlantic. However, we demonstrate that the final desiccation of the Bodélé Basin occurred around 1 ka. Consequently, the present-day mode and scale of dust production from the Bodélé Basin cannot have occurred before 1 ka, suggesting that its role in fertilizing marine and terrestrial ecosystems is either overstated or geologically recent. PMID:26124133

  9. Lake Mega-Chad, a West African Monsoon indicator and tipping element

    NASA Astrophysics Data System (ADS)

    Armitage, Simon; Bristow, Charlie; Drake, Nick

    2015-04-01

    From the deglacial period to the mid-Holocene, North Africa was characterised by much wetter conditions than today. The broad timing of this period, termed the African Humid Period, is well known. However, the rapidity of the onset and termination of the African Humid Period are contested, with strong evidence for both abrupt and gradual change. We use optically stimulated luminescence dating of dunes, shorelines and fluvio-lacustrine deposits to reconstruct the fluctuations of Lake Mega-Chad, which was the largest pluvial lake in Africa. Humid conditions first occur at ~15 ka, followed by a return to relatively arid conditions. By 11.5 ka Lake Mega-Chad had reached a highstand, which persisted until 5.0 ka. Lake levels fell rapidly at 5 ka, indicating abrupt aridification across the entire Lake Mega-Chad Basin. This record provides strong terrestrial evidence that the African Humid Period ended abruptly, supporting the hypothesis that the African monsoon responds to insolation forcing in a markedly non-linear manner. In addition, Lake Mega-Chad exerts strong control on global biogeochemical cycles since the northern (Bodélé) basin is currently the World's greatest single dust source, and possibly an important source of limiting nutrients for both the Amazon basin and equatorial Atlantic. However, we demonstrate that the final desiccation of the Bodélé Basin occurred around 1 ka. Consequently, the present-day mode and scale of dust production from Bodélé Basin cannot have occurred prior to 1 ka, suggesting that its role in fertilizing marine and terrestrial ecosystems is either overstated or geologically recent.

  10. Academics explore humidity's benefits.

    PubMed

    Mortimer, Dave

    2008-11-01

    The effects of humidification on hospital superbugs are being explored by some of the UK's top academics, in what Dave Mortimer, national sales manager for Vapac Humidity Control, explains are the UK's first such studies. PMID:19044148

  11. Humidity without Mystification

    ERIC Educational Resources Information Center

    Staver, Allen E.

    1977-01-01

    Demonstrates how a simple graph can be effectively used in teaching the concept, measurement, and use of humidity. Science activities for upper elementary, secondary, and higher education students are suggested and definitions of terms are presented. (Author/DB)

  12. Acoustic Humidity Sensor

    NASA Technical Reports Server (NTRS)

    Shakkottai, Parthasarathy; Kwack, Eug Y.; Venkateshan, Shakkottai

    1990-01-01

    Industrial humidity sensor measures volume fraction of water in air via its effect on speed of sound. Only portion of sensor exposed to sensed atmosphere is pair of stainless-steel tubes, one containing dry air and other containing moist air. Counters measure intervals between reflected pulses. Sensor rugged enough for use in harsh environments like those used to control drying of paper in paper mills, where most humidity sensors do not survive.

  13. Relationship Factors and Trajectories of Intimate Partner Violence among South African Women during Pregnancy and the Postpartum Period

    PubMed Central

    Groves, Allison K.; McNaughton-Reyes, H. Luz; Foshee, Vangie A.; Moodley, Dhayendre; Maman, Suzanne

    2014-01-01

    Intimate partner violence (IPV) is a significant public health problem in South Africa. However, there is limited research on whether and how IPV changes during pregnancy and the postpartum period and on the factors that might affect women's risk during this time. In this study, we describe the mean trajectories of physical and psychological IPV during pregnancy and the postpartum period and examine whether relationship power, partner social support, and relationship stress are associated with women's trajectories of IPV. Data come from a longitudinal study with 1,480 women recruited during pregnancy between May 2008 and June 2010 at a public clinic in Durban. Women completed behavioral assessments at their first antenatal visit, at fourteen weeks and at nine months postpartum. Women's experiences of IPV were measured at all three time points and relationship power, partner social support and relationship stress were each measured at the baseline assessment. We used multilevel random coefficients growth modeling to build our models. The mean trajectory for both types of IPV was flat which means that, on average, there was not significant change in levels of IPV over pregnancy and the postpartum period. However, there was significant individual variability in trajectories of IPV over the study period. Women who had higher relationship power had lower levels of physical and psychological IPV over time than women with lower relationship power. Additionally, women with higher relationship stress and lower partner support had higher levels of psychological IPV at pregnancy. Interventions that maximize women's relationship power and partner social support and minimize relationship stress during this transformative time are needed. PMID:25268363

  14. Experimental climate warming enforces seed dormancy in South African Proteaceae but seedling drought resilience exceeds summer drought periods.

    PubMed

    Arnolds, Judith L; Musil, Charles F; Rebelo, Anthony G; Krüger, Gert H J

    2015-04-01

    Two hypotheses-that elevated night-time temperatures due to climate warming would enforce post-fire dormancy of Proteaceae seed due to low moisture, and that periods without rain during summer would exceed desiccation periods tolerated by Proteaceae seedlings-were tested empirically. Enforced dormancy, i.e., the inability to germinate due to an environmental restraint, was tested by measuring seed germination in 11 Proteaceae species in experimental mesocosms whose soils were artificially elevated by 1.4 and 3.5 °C above ambient by far-red wavelength filtered infrared lamps. Diminished totality of germination and velocities were observed in 91 and 64%, respectively, of the Proteaceae species tested. Drought resilience was tested in one-year-old seedlings of 16 Proteaceae species by withholding water from potted plants during summer in a greenhouse. The most drought-resilient Proteaceae species displayed the lowest initial transpiration rates at field capacity, the smallest declines in transpiration rate with decreasing soil water content, and the lowest water losses by transpiration. Projected drought periods leading to the complete cessation of transpiration in all Proteaceae species greatly exceeded the number of days without rain per month during summer in the current distribution ranges of those species. It was therefore concluded that enforced seed dormancy induced by elevated night-time temperatures is the post-fire recruitment stage of Proteaceae that is most sensitive to climate warming. PMID:25502439

  15. Hygienic Behavior of Africanized Honey Bees Apis mellifera Directed towards Brood in Old and New Combs during Diurnal and Nocturnal Periods

    PubMed Central

    Pereira, Rogério A.; Morais, Michelle M.; Francoy, Tiago M.; Gonçalves, Lionel S.

    2013-01-01

    Hygienic behavior in honey bees, Apis mellifera, is measured by determining the rate at which the bees uncap and remove dead sealed brood. We analyzed individual behavior of house-cleaning Africanized honey bees in order to focus on some poorly understood aspects of hygienic behavior. Two observation hives, each with approximately 3,000 individually marked bees, were used in this study. The efficiency of hygienic behavior was evaluated in hygienic and non-hygienic strains of bees using two types of combs (new and old), as well as at different periods of the day (night and day). We also recorded the age of workers that performed this task of removing dead brood. In both strains, the workers that performed tasks related to hygienic behavior were within the same age cohort; we found no influence of age on the amount of time dedicated to the task, independent of the type of comb or period of the day. The total time from perforation of the cell capping until the dead brood had been completely removed, and was significantly shorter during daytime than at night. Hygienic behavior directed towards dead brood in new combs was also significantly more efficient (faster) than for brood in old combs. The type of comb had significantly more effect than did the time of day. We conclude that the type of comb and time of day should be taken into consideration when evaluating hygienic behavior in honey bees. PMID:26462521

  16. Disappearance of some human African trypanosomiasis transmission foci in Zambia in the absence of a tsetse fly and trypanosomiasis control program over a period of forty years.

    PubMed

    Mwanakasale, Victor; Songolo, Peter

    2011-03-01

    We conducted a situation analysis of human African trypanosomiasis (HAT) in Zambia from January 2000 to April 2007. The aim of this survey was to identify districts in Zambia that were still recording cases of HAT. Three districts namely, Mpika, Chama, and Chipata were found to be still reporting cases of HAT and thus lay in HAT transmission foci in North Eastern Zambia. During the period under review, 24 cases of HAT were reported from these three districts. We thereafter reviewed literature on the occurrence of HAT in Zambia from the early 1960s to mid 1990s. This revealed that HAT transmission foci were widespread in Western, North Western, Lusaka, Eastern, Luapula, and Northern Provinces of Zambia during this period. In this article we have tried to give possible reasons as to why the distribution of HAT transmission foci is so different between before and after 2000 when there has been no active national tsetse fly and trypanosomiasis control program in Zambia. PMID:21276598

  17. Aging in humid granular media.

    PubMed

    Restagno, Frédéric; Ursini, Cécile; Gayvallet, Hervé; Charlaix, Elisabeth

    2002-08-01

    Aging behavior is an important effect in the friction properties of solid surfaces. In this paper we investigate the temporal evolution of the static properties of a granular medium by studying the aging over time of the maximum stability angle of submillimetric glass beads. We report the effect of several parameters on these aging properties, such as the wear on the beads, the stress during the resting period, and the humidity content of the atmosphere. Aging effects in an ethanol atmosphere are also studied. These experimental results are discussed at the end of the paper. PMID:12241167

  18. Optical humidity sensor

    DOEpatents

    Tarvin, J.A.

    1987-02-10

    An optical dielectric humidity sensor is disclosed which includes a dielectric mirror having multiple alternating layers of two porous water-adsorbent dielectric materials with differing indices of refraction carried by a translucent substrate. A narrow-band polarized light source is positioned to direct light energy onto the mirror, and detectors are positioned to receive light energy transmitted through and reflected by the mirror. A ratiometer indicates humidity in the atmosphere which surrounds the dielectric mirror as a function of a ratio of light energies incident on the detectors. 2 figs.

  19. Optical humidity sensor

    DOEpatents

    Tarvin, Jeffrey A.

    1987-01-01

    An optical dielectric humidity sensor which includes a dielectric mirror having multiple alternating layers of two porous water-adsorbent dielectric materials with differing indices of refraction carried by a translucent substrate. A narrow-band polarized light source is positioned to direct light energy onto the mirror, and detectors are positioned to receive light energy transmitted through and reflected by the mirror. A ratiometer indicates humidity in the atmosphere which surrounds the dielectric mirror as a function of a ratio of light energies incident on the detectors.

  20. Sensitivity of honeybee hygroreceptors to slow humidity changes and temporal humidity variation detected in high resolution by mobile measurements.

    PubMed

    Tichy, Harald; Kallina, Wolfgang

    2014-01-01

    The moist cell and the dry cell on the antenna of the male honeybee were exposed to humidities slowly rising and falling at rates between -1.5%/s and +1.5%/s and at varying amplitudes in the 10 to 90% humidity range. The two cells respond to these slow humidity oscillations with oscillations in impulse frequency which depend not only on instantaneous humidity but also on the rate with which humidity changes. The impulse frequency of each cell was plotted as a function of these two parameters and regression planes were fitted to the data points of single oscillation periods. The regression slopes, which estimate sensitivity, rose with the amplitude of humidity oscillations. During large-amplitude oscillations, moist and dry cell sensitivity for instantaneous humidity and its rate of change was high. During small-amplitude oscillations, their sensitivity for both parameters was low, less exactly reflecting humidity fluctuations. Nothing is known about the spatial and temporal humidity variations a honeybee may encounter when flying through natural environments. Microclimatic parameters (absolute humidity, temperature, wind speed) were measured from an automobile traveling through different landscapes of Lower Austria. Landscape type affected extremes and mean values of humidity. Differences between peaks and troughs of humidity fluctuations were generally smaller in open grassy fields or deciduous forests than in edge habitats or forest openings. Overall, fluctuation amplitudes were small. In this part of the stimulus range, hygroreceptor sensitivity is not optimal for encoding instantaneous humidity and the rate of humidity change. It seems that honeybee's hygroreceptors are specialized for detecting large-amplitude fluctuations that are relevant for a specific behavior, namely, maintaining a sufficiently stable state of water balance. The results suggest that optimal sensitivity of both hygroreceptors is shaped not only by humidity oscillation amplitudes but also

  1. Sensitivity of Honeybee Hygroreceptors to Slow Humidity Changes and Temporal Humidity Variation Detected in High Resolution by Mobile Measurements

    PubMed Central

    Tichy, Harald; Kallina, Wolfgang

    2014-01-01

    The moist cell and the dry cell on the antenna of the male honeybee were exposed to humidities slowly rising and falling at rates between –1.5%/s and +1.5%/s and at varying amplitudes in the 10 to 90% humidity range. The two cells respond to these slow humidity oscillations with oscillations in impulse frequency which depend not only on instantaneous humidity but also on the rate with which humidity changes. The impulse frequency of each cell was plotted as a function of these two parameters and regression planes were fitted to the data points of single oscillation periods. The regression slopes, which estimate sensitivity, rose with the amplitude of humidity oscillations. During large-amplitude oscillations, moist and dry cell sensitivity for instantaneous humidity and its rate of change was high. During small-amplitude oscillations, their sensitivity for both parameters was low, less exactly reflecting humidity fluctuations. Nothing is known about the spatial and temporal humidity variations a honeybee may encounter when flying through natural environments. Microclimatic parameters (absolute humidity, temperature, wind speed) were measured from an automobile traveling through different landscapes of Lower Austria. Landscape type affected extremes and mean values of humidity. Differences between peaks and troughs of humidity fluctuations were generally smaller in open grassy fields or deciduous forests than in edge habitats or forest openings. Overall, fluctuation amplitudes were small. In this part of the stimulus range, hygroreceptor sensitivity is not optimal for encoding instantaneous humidity and the rate of humidity change. It seems that honeybee's hygroreceptors are specialized for detecting large-amplitude fluctuations that are relevant for a specific behavior, namely, maintaining a sufficiently stable state of water balance. The results suggest that optimal sensitivity of both hygroreceptors is shaped not only by humidity oscillation amplitudes but also

  2. Hands-on Humidity.

    ERIC Educational Resources Information Center

    Pankiewicz, Philip R.

    1992-01-01

    Presents five hands-on activities that allow students to detect, measure, reduce, and eliminate moisture. Students make a humidity detector and a hygrometer, examine the effects of moisture on different substances, calculate the percent of water in a given food, and examine the absorption potential of different desiccants. (MDH)

  3. Desiccant humidity control system

    NASA Technical Reports Server (NTRS)

    Amazeen, J. (Editor)

    1973-01-01

    A regenerable sorbent system was investigated for controlling the humidity and carbon dioxide concentration of the space shuttle cabin atmosphere. The sorbents considered for water and carbon dioxide removal were silica gel and molecular sieves. Bed optimization and preliminary system design are discussed along with system optimization studies and weight penalites.

  4. Why HVAC commissioning procedures do not work in humid climates

    SciTech Connect

    DuBose, G.H.; Odom, J.D. III; Fairey, P.W.

    1993-12-01

    This article discusses ways to avoid moisture damage to buildings caused by improper commissioning of HVAC systems during periods of high humidity. The topics of the article include moisture control strategies, air leakage in hot, humid climates, commissioning HVAC systems, and case studies covering central exhaust systems, building chases being used as air distribution systems, and leakage at guest room fan coil units.

  5. VAB Temperature and Humidity Study

    NASA Technical Reports Server (NTRS)

    Lane, John E.; Youngquist, Robert C.; Muktarian, Edward; Nurge, Mark A.

    2014-01-01

    In 2012, 17 data loggers were placed in the VAB to measure temperature and humidity at 10-minute intervals over a one-year period. In 2013, the data loggers were replaced with an upgraded model and slight adjustments to their locations were made to reduce direct solar heating effects. The data acquired by the data loggers was compared to temperature data provided by three wind towers located around the building. It was found that the VAB acts as a large thermal filter, delaying and reducing the thermal oscillations occurring outside of the building. This filtering is typically more pronounced at higher locations in the building, probably because these locations have less thermal connection with the outside. We surmise that the lower elevations respond more to outside temperature variations because of air flow through the doors. Temperatures inside the VAB rarely exceed outdoor temperatures, only doing so when measurements are made directly on a surface with connection to the outside (such as a door or wall) or when solar radiation falls directly on the sensor. A thermal model is presented to yield approximate filter response times for various locations in the building. Appendix A contains historical thermal and humidity data from 1994 to 2009.

  6. All-Optical Graphene Oxide Humidity Sensors

    PubMed Central

    Lim, Weng Hong; Yap, Yuen Kiat; Chong, Wu Yi; Ahmad, Harith

    2014-01-01

    The optical characteristics of graphene oxide (GO) were explored to design and fabricate a GO-based optical humidity sensor. GO film was coated onto a SU8 polymer channel waveguide using the drop-casting technique. The proposed sensor shows a high TE-mode absorption at 1550 nm. Due to the dependence of the dielectric properties of the GO film on water content, this high TE-mode absorption decreases when the ambient relative humidity increases. The proposed sensor shows a rapid response (<1 s) to periodically interrupted humid air flow. The transmission of the proposed sensor shows a linear response of 0.553 dB/% RH in the range of 60% to 100% RH. PMID:25526358

  7. A distal 140 kyr sediment record of Nile discharge and East African monsoon variability

    NASA Astrophysics Data System (ADS)

    Ehrmann, Werner; Schmiedl, Gerhard; Seidel, Martin; Krüger, Stefan; Schulz, Hartmut

    2016-03-01

    Clay mineral assemblages in a sediment core from the distal Nile discharge plume off Israel have been used to reconstruct the late Quaternary Nile sediment discharge into the eastern Mediterranean Sea (EMS). The record spans the last ca. 140 kyr. Smectite abundances indicate the influence of the Blue Nile and the Atbara River that have their headwaters in the volcanic rocks of the Ethiopian Highlands. Kaolinite abundances indicate the influence of wadis, which contribute periodically to the suspension load of the Nile. Due to the geographical position, the climate and the sedimentary framework of the EMS is controlled by two climate systems. The long-term climate regime was governed by the African monsoon that caused major African humid periods (AHPs) with enhanced sediment discharge at 132 to < 126 (AHP 5), 116 to 99 (AHP4), and 89 to 77 ka (AHP3). They lasted much longer than the formation of the related sapropel layers S5 (> 2 kyr), S4 (3.5 kyr), and S3 (5 kyr). During the last glacial period (Marine Isotope Stages (MISs) 4-2), the long-term changes in the monsoonal system were superimposed by millennial-scale changes in an intensified midlatitude glacial system. This climate regime caused short but pronounced drought periods in the Nile catchment, which are linked to Heinrich events and alternate with more humid interstadials. The clay mineral record further implies that feedback mechanisms between vegetation cover and sediment discharge of the Nile are detectable but of minor importance for the sedimentary record in the southeastern Mediterranean Sea during the investigated African humid periods.

  8. Genome-wide identification of signatures of positive selection in African admixed zebu cattle

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The introduction of humped zebu to the African continent has led to genetic introgression with the local African humpless taurine. A mosaic of zebu x taurine cattle populations adapted to the local environments (e.g., semi-dry desert, humid and sub-humid forested areas) has arisen as a result of thi...

  9. Heat or humidity, which triggers tree phenology?

    NASA Astrophysics Data System (ADS)

    Laube, Julia; Sparks, Tim H.; Estrella, Nicole; Menzel, Annette

    2014-05-01

    An overwhelming number of studies confirm that temperature is the main driver for phenological events such as leafing, flowering or fruit ripening, which was first discovered by Réaumur in 1735. Since then, several additional factors which influence onset dates have been identified, such as length of the chilling period, photoperiod, temperature of the previous autumn, nutrient availability, precipitation, sunshine and genetics (local adaptations). Those are supposed to capture some of the remaining, unexplained variance. But our ability to predict onset dates remains imprecise, and our understanding of how plants sense temperature is vague. From a climate chamber experiment on cuttings of 9 tree species we present evidence that air humidity is an important, but previously overlooked, factor influencing the spring phenology of trees. The date of median leaf unfolding was 7 days earlier at 90% relative humidity compared to 40% relative humidity. A second experiment with cuttings shows that water uptake by above-ground tissue might be involved in the phenological development of trees. A third climate chamber experiment suggests that winter dormancy and chilling might be linked to dehydration processes. Analysis of climate data from several meteorological stations across Germany proves that the increase in air humidity after winter is a reliable signal of spring, i.e. less variable or susceptible to reversal compared to temperature. Finally, an analysis of long-term phenology data reveals that absolute air humidity can even be used as a reliable predictor of leafing dates. Current experimental work tries to elucidate the involved foliar uptake processes by using deuterium oxide marked water and Raman spectroscopy. We propose a new framework, wherein plants' chilling requirements and frost tolerance might be attributed to desiccation processes, while spring development is linked to re-humidification of plant tissue. The influence of air humidity on the spring

  10. Economic Aspects of Agricultural Development in Africa. A Selective Annotated Reading List of Reports and Studies Concerning 40 African Countries During the Period 1960 - 1969.

    ERIC Educational Resources Information Center

    Neville-Rolfe, Edmund, Comp.

    Some 1394 research studies from various African countries are annotated in this bibliography, which is divided into 37 country sections with a separate section (Africa General) for studies dealing with the continent as a whole, with geographical regions, or with groups of countries. The publications listed and summarized were published primarily…

  11. Crystal Microbalance Monitors Relative Humidity

    NASA Technical Reports Server (NTRS)

    Yang, L. C.

    1984-01-01

    Sensor monitors water evaporation in industrial drying processes. Measured adsorption isotherm for instrument essentially linear over entire range of relative humidity. Testing at each temperature setting less than half hour for full relative-humidity range, with estimated frequency response time less than 10 seconds. Used to measure relative humidity of ambient atmosphere near drying paper, food textile fabrics and pulp to optimize water-drying portion of processing cycle.

  12. Improving irrigation management for humid and sub-humid climates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This project includes studies led by both USDA-ARS and University of Missouri scientists, with a goal to develop solutions to broad water management problems with application to humid and sub-humid areas in the USA and the world. Our interdisciplinary team optimizes production systems for irrigated ...

  13. Improving irrigation management for humid and sub-humid climates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This project includes studies led by both USDA-ARS and University of Missouri scientists, with a goal to develop solutions to broad water management problems with application to humid and sub-humid areas in the USA and the world. Our interdisciplinary team evaluates and optimizes production systems ...

  14. Upper tropospheric humidity changes under constant relative humidity

    NASA Astrophysics Data System (ADS)

    Gierens, Klaus; Eleftheratos, Kostas

    2016-03-01

    Theoretical derivations are given on the change of upper tropospheric humidity (UTH) in a warming climate. The considered view is that the atmosphere, which is getting moister with increasing temperatures, will retain a constant relative humidity. In the present study, we show that the upper tropospheric humidity, a weighted mean over a relative humidity profile, will change in spite of constant relative humidity. The simple reason for this is that the weighting function that defines UTH changes in a moister atmosphere. Through analytical calculations using observations and through radiative transfer calculations, we demonstrate that two quantities that define the weighting function of UTH can change: the water vapour scale height and the peak emission altitude. Applying these changes to real profiles of relative humidity shows that absolute UTH changes typically do not exceed 1 %. If larger changes would be observed they would be an indication of climatological changes of relative humidity. As such, an increase in UTH between 1980 and 2009 in the northern midlatitudes, as shown by earlier studies using the High-resolution Infrared Radiation Sounder (HIRS) data, may be an indication of an increase in relative humidity as well.

  15. Upper-tropospheric humidity changes under constant relative humidity

    NASA Astrophysics Data System (ADS)

    Gierens, K.; Eleftheratos, K.

    2015-10-01

    Theoretical derivations are given on the change of upper-tropospheric humidity (UTH) in a warming climate. Considered view is that the atmosphere, getting moister with increasing temperatures, will retain a constant relative humidity. In the present study we show that the upper-tropospheric humidity, a weighted mean over a relative humidity profile, will change in spite of constant relative humidity. The simple reason for this is that the weighting function, that defines UTH, changes in a moister atmosphere. Through analytical calculations using observations and through radiative transfer calculations we demonstrate that two quantities that define the weighting function of UTH can change: the water vapour scale height and the peak emission altitude. Applying these changes to real profiles of relative humidity shows that absolute UTH changes typically do not exceed 1 %. If larger changes would be observed they would be an indication of climatological changes of relative humidity. As such, an increase in UTH between 1980 and 2009 in the northern midlatitudes as shown by earlier studies using HIRS data, may be an indication of an increase in relative humidity as well.

  16. Report Card on Humidity Control.

    ERIC Educational Resources Information Center

    Fischer, John C.; Bayer, Charlene

    2003-01-01

    Reports on an investigation of the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Standard 62-1999 on outdoor ventilation rates and space humidity levels for schools. Examined conventional cooling versus desiccant-based systems designed to control indoor humidity levels. Discusses the effectiveness of systems…

  17. Humidity Graphs for All Seasons.

    ERIC Educational Resources Information Center

    Esmael, F.

    1982-01-01

    In a previous article in this journal (Vol. 17, p358, 1979), a wet-bulb depression table was recommended for two simple experiments to determine relative humidity. However, the use of a graph is suggested because it gives the relative humidity directly from the wet and dry bulb readings. (JN)

  18. Humidity assay for studying plant-pathogen interactions in miniature controlled discrete humidity environments with good throughput.

    PubMed

    Xu, Zhen; Jiang, Huawei; Sahu, Binod Bihari; Kambakam, Sekhar; Singh, Prashant; Wang, Xinran; Wang, Qiugu; Bhattacharyya, Madan K; Dong, Liang

    2016-05-01

    This paper reports a highly economical and accessible approach to generate different discrete relative humidity conditions in spatially separated wells of a modified multi-well plate for humidity assay of plant-pathogen interactions with good throughput. We demonstrated that a discrete humidity gradient could be formed within a few minutes and maintained over a period of a few days inside the device. The device consisted of a freeway channel in the top layer, multiple compartmented wells in the bottom layer, a water source, and a drying agent source. The combinational effects of evaporation, diffusion, and convection were synergized to establish the stable discrete humidity gradient. The device was employed to study visible and molecular disease phenotypes of soybean in responses to infection by Phytophthora sojae, an oomycete pathogen, under a set of humidity conditions, with two near-isogenic soybean lines, Williams and Williams 82, that differ for a Phytophthora resistance gene (Rps1-k). Our result showed that at 63% relative humidity, the transcript level of the defense gene GmPR1 was at minimum in the susceptible soybean line Williams and at maximal level in the resistant line Williams 82 following P. sojae CC5C infection. In addition, we investigated the effects of environmental temperature, dimensional and geometrical parameters, and other configurational factors on the ability of the device to generate miniature humidity environments. This work represents an exploratory effort to economically and efficiently manipulate humidity environments in a space-limited device and shows a great potential to facilitate humidity assay of plant seed germination and development, pathogen growth, and plant-pathogen interactions. Since the proposed device can be easily made, modified, and operated, it is believed that this present humidity manipulation technology will benefit many laboratories in the area of seed science, plant pathology, and plant-microbe biology, where

  19. Measure Guideline: Supplemental Dehumidification in Warm-Humid Climates

    SciTech Connect

    Rudd, Armin

    2014-10-01

    This document covers a description of the need and applied solutions for supplemental dehumidification in warm-humid climates, especially for energy efficient homes where the sensible cooling load has been dramatically reduced. Cooling loads are typically high and cooling equipment runs a lot to cool the air in older homes in warm-humid climates. The cooling process also removes indoor moisture, reducing indoor relative humidity. However, at current residential code levels, and especially for above-code programs, sensible cooling loads have been so dramatically reduced that the cooling system does not run a lot to cool the air, resulting in much less moisture being removed. In these new homes, cooling equipment is off for much longer periods of time especially during spring/fall seasons, summer shoulder months, rainy periods, some summer nights, and winter days. In warm-humid climates, those long-off periods allow indoor humidity to become elevated due to internally generated moisture and ventilation air change. Elevated indoor relative humidity impacts comfort, indoor air quality, and building material durability. Industry is responding with supplemental dehumidification options, but that effort is really in its infancy regarding year-round humidity control in low-energy homes. Available supplemental humidity control options are discussed. Some options are less expensive but may not control indoor humidity as well as more expensive and comprehensive options. The best performing option is one that avoids overcooling and adding unnecessary heat to the space by using waste heat from the cooling system to reheat the cooled and dehumidified air to room-neutral temperature.

  20. Measure Guideline: Supplemental Dehumidification in Warm-Humid Climates

    SciTech Connect

    Rudd, A.

    2014-10-01

    This document covers a description of the need and applied solutions for supplemental dehumidification in warm-humid climates, especially for energy efficient homes where the sensible cooling load has been dramatically reduced. In older homes in warm-humid climates, cooling loads are typically high and cooling equipment runs a lot to cool the air. The cooling process also removes indoor moisture, reducing indoor relative humidity. However, at current residential code levels, and especially for above-code programs, sensible cooling loads have been so dramatically reduced that the cooling system does not run a lot to cool the air, resulting in much less moisture being removed. In these new homes, cooling equipment is off for much longer periods of time especially during spring/fall seasons, summer shoulder months, rainy periods, some summer nights, and some winter days. In warm-humid climates, those long off periods allow indoor humidity to become elevated due to internally generated moisture and ventilation air change. Elevated indoor relative humidity impacts comfort, indoor air quality, and building material durability. Industry is responding with supplemental dehumidification options, but that effort is really in its infancy regarding year-round humidity control in low-energy homes. Available supplemental humidity control options are discussed. Some options are less expensive but may not control indoor humidity as well as more expensive and comprehensive options. The best performing option is one that avoids overcooling and avoids adding unnecessary heat to the space by using waste heat from the cooling system to reheat the cooled and dehumidified air to room-neutral temperature.

  1. Gas and humidity sensing element

    SciTech Connect

    Komine, Y.; Sawada, T.

    1984-06-26

    A gas and humidity sensing element in a single integral structure made of a base plate of apatite ceramics, on which a particular metal oxide such as tin oxide, zinc oxide, or composite oxide of titanium and niobium is provided. The sensing element has a function of sensing gas and humidity with outstanding sensitivity to bad smell gas and alcoholic gas, in which the humidity is sensed and measured by variations in electrical resistance of the apatite ceramic base plate and the bad smell gas such as hydrogen sulfide, methyl mercaptan, etc. is sensed and measured by variations in electrical resistance of the metal oxide.

  2. Temperature, Humidity, And Polymer Aging

    NASA Technical Reports Server (NTRS)

    Cuddihy, Edward F.

    1988-01-01

    Report presents analysis of experimental data on electrical resistivity of polymer (polyvinyl butyral) as function of temperature and relative humidity. Resulting theoretical expression for electrical resistivity resembles generally accepted empirical law for the corrosion rate.

  3. Humidity testing of bleached holograms.

    PubMed

    Chenoweth, A J

    1971-04-01

    One of the proposed storage media for semipermanent optical stores is an array of bleached holograms fabricated on photographic plates. If a store utilizing this medium is to be operated in a field environment, the effect of humidity variation requires consideration. In this study holograms were made using either Burckhardt's potassium ferricyanide or Russo and Sottini's modified R-10 type bleach on Kodak 649F and Agfa 10E70 plates. Diffraction efficiency was measured as a function of relative humidity over the range 30-98%. For holograms fabricated and tested as described above it was found that relative humidity values above 75% caused a permanent loss in diffraction efficiency for potassium ferricyanide bleached plates; humidity above 90% produced a temporary loss in R-10 bleached plates. PMID:20094561

  4. Humidity sensing with doped polyaniline

    NASA Astrophysics Data System (ADS)

    Jain, Shilpa; Chakane, Sanjay D. S.; Bhoraskar, S. V.; Samui, A. B.; Krishnamurthy, V. N.

    2001-03-01

    Polyaniline (PANI) was doped with different dopants like camphosulphoric acid (CSA), diphenyl phosphate (DPPH), Sulphonic acid (S) and Maleic acid (MAC) by chemical method. The samples were prepared in the form of pellets as well as films. Polyaniline doped with Maleic acid was found to be mechanically and chemically stable as compared to other dopants and therefore the effect of humidity on conductivity was further investigated. Films prepared out of styrene buryl acrylate copolymer with different concentrations of PANI Maleic acid were used for sensing humidity ranging between 20% to 90% relative humidity. A maximum change in the conductivity of three to four orders of magnitude was obtained for the Maleic acid doped polyaniline pellet while two orders of magnitude change was obtained for the film samples over the range of humidity measured.

  5. A distal 145 ka sediment record of Nile discharge and East African monsoon variability

    NASA Astrophysics Data System (ADS)

    Ehrmann, W.; Schmiedl, G.; Seidel, M.; Krüger, S.; Schulz, H.

    2015-09-01

    Clay mineral assemblages in a sediment core from the distal Nile discharge plume off Israel have been used to reconstruct the late Quaternary Nile sediment discharge into the Eastern Mediterranean Sea (EMS). The record spans the last ca. 145 ka. Smectite abundances indicate the influence of the Blue Nile and Atbara that have their headwaters in the volcanic rocks of the Ethiopian highlands. Kaolinite abundances indicate the influence of wadis, which contribute periodically to the suspension load of the Nile. Due to the geographical position, the climate and the sedimentary framework of the EMS is controlled by two climate systems. The long-term climate regime was governed by the African monsoon that caused major humid periods with enhanced sediment discharge at 132 to < 122 ka (AHP 5), 113 to 104 ka (AHP 4), and 86 to 74 ka (AHP 3). They lasted much longer than the formation of the related sapropel layers S5, S4 and S3. During the last glacial period (MIS 4-2) the long-term changes of the monsoonal system were superimposed by millennial-scale changes of an intensified mid-latitude glacial system. This climate regime caused short but pronounced drought periods in the Nile catchment, which are linked to Heinrich Events and alternate with more humid interstadials. The clay mineral record further implies that feedback mechanisms between vegetation cover and sediment discharge of the Nile are detectable but of minor importance for the sedimentary record in the southeastern Mediterranean Sea during the investigated African Humid Periods.

  6. Changes in opal fluxes along the northwest African margin during the last glacial period; linking high and low latitude patterns of productivity

    NASA Astrophysics Data System (ADS)

    Bradtmiller, L. I.; Galgay, M.; McGee, D.; Kinsley, C. W.; Anderson, R. F.

    2014-12-01

    Recent studies have proposed competing hypotheses to explain increased opal fluxes in high and low latitudes during the most recent deglaciation. Anderson et al. (2009) rely on increased wind-driven upwelling in the Southern Ocean to explain the increased availability of Si in both the Southern Ocean and tropical thermoclines, leading to increased opal fluxes in both regions coincident with the deglacial rise in CO2. Meckler et al. (2013) suggest that a decrease in the presence of North Atlantic intermediate water (GNAIW) during the deglaciation allowed Si-rich southern-sourced waters to fill the tropical Atlantic leading to increased opal burial. We attempt to distinguish between these two mechanisms by reconstructing opal fluxes and fluxes of windblown dust over the past ~65ka at four sites along the northwest African margin. The records include the deglaciation, including Heinrich Event 1 (H1) and the Younger Dryas (YD), as well as several earlier Heinrich events. We find that opal and dust fluxes increase simultaneously during the deglaciation, and more highly resolved cores record H1 and the YD as distinct peaks within the deglaciation. Furthermore, opal and dust fluxes scale approximately linearly with one another during these events. We observe opal peaks associated with most Heinrich Events through H6. Finally, we observe a strong similarity between patterns of opal flux in the Southern Ocean and along the African Margin. This suggests that the pattern of diatom productivity and opal flux along the African Margin reflects a combination of changes in wind strength due to shifting temperature gradients, and changes in the export of silica-rich water from the Southern Ocean, both as a result of the global scale climate changes associated with Heinrich Events. Anderson, R. F., S. Ali, L. I. Bradtmiller, S. H. H. Nielsen, M. Q. Fleisher, B. E. Anderson and L. H. Burckle. Wind-Driven Upwelling in the Southern Ocean and the Deglacial Rise in Atmospheric CO2

  7. Single time point isothermal drug stability experiments at constant humidity.

    PubMed

    Tao, Jian-Lin; Zhan, Xian-Cheng; Li, Lin-Li; Lin, Bing; Jiang, Lu

    2009-03-01

    A single time point isothermal drug stability experiments at constant humidity is introduced. In the new method, kinetic parameters related to both moisture and temperature were obtained by a single pair of experiments: these related to moisture by one with a group of testing humidities and a fixed temperature, those related to temperature by the other with a group of testing temperatures and a constant humidity. By a simulation, the estimates for the kinetic parameters (E(a), m, A) obtained by the proposed method and the reported programmed humidifying and heating method were statistically evaluated and were compared with those obtained by the isothermal measurements at constant humidity. Results indicated that under the same experimental conditions, the estimates obtained by the proposed method were significantly more precise than those obtained by the reported programmed humidifying and heating method. The estimates obtained by the isothermal method at constant humidity were somewhat more precise than those obtained by the proposed method. However, the experimental period needed by the isothermal method at constant humidity was greatly longer than that needed by the proposed method. The stability of dicloxacillin sodium, as a solid state model, was investigated by the single time point isothermal drug stability experiments at constant humidity. The results indicated that the kinetic parameters obtained by the proposed method were comparable to those from the reported. PMID:19252391

  8. Fiberboard Humidity Data for 9975 Shipping Packages

    SciTech Connect

    Daugherty, W.

    2015-07-31

    The 9975 surveillance program is identifying a technical basis to support extending the storage period of 9975 packages in KAC beyond the currently approved 15 years. A key element of this effort is developing a better understanding of degradation of the fiberboard assembly under storage conditions. This degradation is influenced greatly by the moisture content of the fiberboard, which is not well characterized on an individual package basis. Two efforts have been undertaken to better understand the levels and behavior of moisture within the fiberboard assemblies of the 9975 shipping package. In the first effort, an initial survey of humidity and temperature in the upper air space of 26 packages stored in KAC was made. The data collected within this first effort help to illustrate how the upper air space humidity varies with the local ambient temperature and package heat load. In the second effort, direct measurements of two test packages are providing a correlation between humidity and fiberboard moisture levels within the package, and variations in moisture throughout the fiberboard assembly. This effort has examined packages with cane fiberboard and internal heat levels of 5 and 10W to date. Additional testing is expected to include 15 and 19W heat levels, and then repeat the same four heat levels with softwood fiberboard assemblies. This report documents the data collected to date within these two efforts

  9. Fiberboard humidity data for 9975 shipping packages

    SciTech Connect

    Daugherty, W. L.

    2015-07-31

    The 9975 surveillance program is identifying a technical basis to support extending the storage period of 9975 packages in KAC beyond the currently approved 15 years. A key element of this effort is developing a better understanding of degradation of the fiberboard assembly under storage conditions. This degradation is influenced greatly by the moisture content of the fiberboard, which is not well characterized on an individual package basis.Two efforts have been undertaken to better understand the levels and behavior of moisture within the fiberboard assemblies of the 9975 shipping package. In the first effort, an initial survey of humidity and temperature in the upper air space of 26 packages stored in KAC was made. The data collected within this first effort help to illustrate how the upper air space humidity varies with the local ambient temperature and package heat load. In the second effort, direct measurements of two test packages are providing a correlation between humidity and fiberboard moisture levels within the package, and variations in moisture throughout the fiberboard assembly. This effort has examined packages with cane fiberboard and internal heat levels of 5 and 10W to date. Additional testing is expected to include 15 and 19W heat levels, and then repeat the same four heat levels with softwood fiberboard assemblies. This report documents the data collected to date within these two efforts.

  10. Coherent changes of southeastern equatorial and northern African rainfall during the last deglaciation.

    PubMed

    Otto-Bliesner, Bette L; Russell, James M; Clark, Peter U; Liu, Zhengyu; Overpeck, Jonathan T; Konecky, Bronwen; deMenocal, Peter; Nicholson, Sharon E; He, Feng; Lu, Zhengyao

    2014-12-01

    During the last deglaciation, wetter conditions developed abruptly ~14,700 years ago in southeastern equatorial and northern Africa and continued into the Holocene. Explaining the abrupt onset and hemispheric coherence of this early African Humid Period is challenging due to opposing seasonal insolation patterns. In this work, we use a transient simulation with a climate model that provides a mechanistic understanding of deglacial tropical African precipitation changes. Our results show that meltwater-induced reduction in the Atlantic meridional overturning circulation (AMOC) during the early deglaciation suppressed precipitation in both regions. Once the AMOC reestablished, wetter conditions developed north of the equator in response to high summer insolation and increasing greenhouse gas (GHG) concentrations, whereas wetter conditions south of the equator were a response primarily to the GHG increase. PMID:25477460

  11. Determinants of the risk of dying of HIV/AIDS in a rural South African community over the period of the decentralised roll-out of antiretroviral therapy: a longitudinal study

    PubMed Central

    Mee, Paul; Collinson, Mark A.; Madhavan, Sangeetha; Kabudula, Chodziwadziwa; Gómez-Olivé, Francesc Xavier; Kahn, Kathleen; Tollman, Stephen M.; Hargreaves, James; Byass, Peter

    2014-01-01

    Background Antiretroviral treatment (ART) has significantly reduced HIV mortality in South Africa. The benefits have not been experienced by all groups. Here we investigate the factors associated with these inequities. Design This study was located in a rural South African setting and used data collected from 2007 to 2010, the period when decentralised ART became available. Approximately one-third of the population were of Mozambican origin. There was a pattern of repeated circular migration between urban areas and this community. Survival analysis models were developed to identify demographic, socioeconomic, and spatial risk factors for HIV mortality. Results Among the study population of 105,149 individuals, there were 2,890 deaths. The HIV/TB mortality rate decreased by 27% between 2007–2008 and 2009–2010. For other causes of death, the reduction was 10%. Bivariate analysis found that the HIV/TB mortality risk was lower for: those living within 5 km of the Bhubezi Community Health Centre; women; young adults; in-migrants with a longer period of residence; permanent residents; and members of households owning motorised transport, holding higher socioeconomic positions, and with higher levels of education. Multivariate modelling showed, in addition, that those with South Africa as their country of origin had an increased risk of HIV/TB mortality compared to those with Mozambican origins. For males, those of South African origin, and recent in-migrants, the risk of death associated with HIV/TB was significantly greater than that due to other causes. Conclusions In this community, a combination of factors was associated with an increased risk of dying of HIV/TB over the period of the roll-out of ART. There is evidence for the presence of barriers to successful treatment for particular sub-groups in the population, which must be addressed if the recent improvements in population-level mortality are to be maintained. PMID:25416322

  12. Evidence for a late Holocene warm and humid climate period and environmental characteristics in the arid zones of northwest China during 2.2 ˜ 1.8 kyr B.P.

    NASA Astrophysics Data System (ADS)

    Bao, Yang; Braeuning, Achim; Yafeng, Shi; Fahu, Chen

    2004-01-01

    Natural archives like ice cores, tree rings, river and lake sediments, lake terraces, and paleosols and also historical documents witness aspects of climate change in northwestern China during the Western and Eastern Han Dynasties (206 B.C.-220 A.D.). Reconstructions of decadal averages of annual mean temperature and precipitation fluctuations were derived from variations of δ18O and net accumulation rates in the Guliya ice core. They revealed a period of higher temperatures and higher precipitation than today, which affected vast areas of northwestern China during the period of interest until the fifth century A.D. These conditions resulted in a marked increase in the discharge of big endorheic river systems, such as the Tarim, the Keriya and the Manas rivers. As a consequence, water levels in appendant terminal lakes rose, e.g., at Lop Nor, Manas Lake, and Baijian Hu. Lake surface areas expanded, and lake desalting occurred also at lakes in intermontane basins, such as Balikun Hu and Qinghai Lake. The warm and moist conditions during the Western and Eastern Han Dynasties might have been responsible for the large-scale agricultural production and the local socioeconomic boom that is documented by the occurrence of the famous ruin groups of Loulan, Niya, and Keriya. The following desiccation phase led to a deterioration of water resources, and most oases tended to dry out and were finally abandoned. The appearance, development, flourishing, and final abandonment of each great ruin group are closely associated with regional climate change at that time.

  13. Western Africa to c/1860 A.D.: A Provisional Historical Schema Based on Climate Periods. Indiana University African Studies Program Working Papers Series, No. 1.

    ERIC Educational Resources Information Center

    Brooks, George E.

    An examination of historical developments in western Africa during six climate periods extending over two millennia, this study demonstrates that numerous historical developments correlate with climate periods and/or were influenced by changes in rainfall patterns and ecological conditions. These include such diverse topics as the diffusion of…

  14. Ultrahigh humidity sensitivity of graphene oxide

    PubMed Central

    Bi, Hengchang; Yin, Kuibo; Xie, Xiao; Ji, Jing; Wan, Shu; Sun, Litao; Terrones, Mauricio; Dresselhaus, Mildred S.

    2013-01-01

    Humidity sensors have been extensively used in various fields, and numerous problems are encountered when using humidity sensors, including low sensitivity, long response and recovery times, and narrow humidity detection ranges. Using graphene oxide (G-O) films as humidity sensing materials, we fabricate here a microscale capacitive humidity sensor. Compared with conventional capacitive humidity sensors, the G-O based humidity sensor has a sensitivity of up to 37800% which is more than 10 times higher than that of the best one among conventional sensors at 15%–95% relative humidity. Moreover, our humidity sensor shows a fast response time (less than 1/4 of that of the conventional one) and recovery time (less than 1/2 of that of the conventional one). Therefore, G-O appears to be an ideal material for constructing humidity sensors with ultrahigh sensitivity for widespread applications. PMID:24048093

  15. Ultrafast graphene oxide humidity sensors.

    PubMed

    Borini, Stefano; White, Richard; Wei, Di; Astley, Michael; Haque, Samiul; Spigone, Elisabetta; Harris, Nadine; Kivioja, Jani; Ryhänen, Tapani

    2013-12-23

    Sensors allow an electronic device to become a gateway between the digital and physical worlds, and sensor materials with unprecedented performance can create new applications and new avenues for user interaction. Graphene oxide can be exploited in humidity and temperature sensors with a number of convenient features such as flexibility, transparency and suitability for large-scale manufacturing. Here we show that the two-dimensional nature of graphene oxide and its superpermeability to water combine to enable humidity sensors with unprecedented response speed (∼30 ms response and recovery times). This opens the door to various applications, such as touchless user interfaces, which we demonstrate with a 'whistling' recognition analysis. PMID:24206232

  16. Doing hydrology backwards in tropical humid catchments

    NASA Astrophysics Data System (ADS)

    Real Rangel, R.; Brena-Naranjo, J. A.; Pedrozo-Acuña, A.

    2015-12-01

    Top-down approaches in hydrology offer the possibility to predict water fluxes at the catchment scale based on the interpretation of the observed hydrological response at the catchment itself. Doing hydrology backwards (inferring precipitation and evapotranspiration rates at the catchment scale from streamflow measurements, see Kirchner (2009)) can be a useful methodology for estimating water fluxes at the catchment and regional scales. Previous studies using this inverse modeling approach have been performed in regions (UK, Switzerland, France, Eastern US) where energy-limited (in winter and early spring) and water-limited conditions (in summer) prevail during a large period of the year. However, such approach has not been tested in regions characterized by a quasi-constant supply of water and energy (e.g. humid tropics). The objective of this work is to infer annual rates of precipitation and evapotranspiration over the last decade in 10 catchments located in Mexico's tropical humid regions. Hourly discharge measurements during recession periods were analyzed and parameters for the nonlinear storage-discharge relationship of each catchment were derived. Results showed large variability in both catchment-scale precipitation and evapotranspiration rates among the selected study sites. Finally, a comparison was done between such estimates and those obtained from remotely-sensed data (TRMM for precipitation and MOD16 for evapotranspiration).

  17. Relative humidity from psychrometric data

    NASA Technical Reports Server (NTRS)

    Putnam, T. W.

    1976-01-01

    Analytical equation for computing relative humidity as function of wet bulb temperature, dry bulb temperature, and atmospheric pressure is suitable for use with calculator or computer. Analytical expressions may be useful for chemical process control systems and building environmental control systems.

  18. Comparing the effect of modeled climatic variables on the distribution of African horse sickness in South Africa and Namibia.

    PubMed

    Liebenberg, Danica; van Hamburg, Huib; Piketh, Stuart; Burger, Roelof

    2015-12-01

    Africa horse sickness (AHS) is a lethal disease of horses with a seasonal occurrence that is influenced by environmental conditions that favor the development of Culicoides midges (Diptera: Ceratopogonidae). This study compared and evaluated the relationship of various modeled climatic variables with the distribution and abundance of AHS in South Africa and Namibia. A comprehensive literature review of the historical AHS reported data collected from the Windhoek archives as well as annual reports from the Directorate of Veterinary services in Namibia were conducted. South African AHS reported data were collected from the South African Department of Agriculture, Forestry, and Fisheries. Daily climatic data were extracted for the time period 1993-2011 from the ERA-interim re-analysis dataset. The principal component analysis of the complete dataset indicated a significant statistical difference between Namibia and South Africa for the various climate variables and the outbreaks of AHS. The most influential parameters in the distribution of AHS included humidity, precipitation, evaporation, and minimum temperature. In South Africa, temperature had the most significant effect on the outbreaks of AHS, whereas in Namibia, humidity and precipitation were the main drivers. The maximum AHS cases in South Africa occurred at temperatures of 20-22° C and relative humidity between 50-70%. Furthermore, anthropogenic effects must be taken into account when trying to understand the distribution of AHS. PMID:26611969

  19. Homogenisation of relative humidity necessary and possible?

    NASA Astrophysics Data System (ADS)

    Chimani, Barbara; Andre, Konrad; Lexer, Annemarie; Nemec, Johanna; Auer, Ingeborg; Venema, Victor

    2015-04-01

    Data homogenisation is an essential part of reliable climate data analyses for example concerning trend analyses. Up to now mainly methods for homogenising monthly data have been developed. For daily data homogenization tests especially for temperature and precipitation have been worked out as those are of main interest concerning climate change. But more sophisticated attempts of analyses need additional climate parameters as well. Therefore the existing homogenisation methods are applied on relative humidity. In order to have a possibility to estimate performance of the different methods those tests have been applied on a so-called surrogate dataset, resembling the statistical properties of the measured time series. Artificial inhomogenities were introduced to this dataset in three steps: (1) deterministic change points: within one homogeneous sub-period (HSP) a constant perturbation is added to each relative humidity values, (2) deterministic + random changes: random changes do not change the mean of the HSP but can affect the distribution of the parameter, (3) deterministic + random changes + a clear trend signals. The methods MASH (Szentimrey, 1999), ACMANT (Domonkos, 2011), PRODIGE (Caussinus and Mestre, 2004), SNHT (Alexandersson, 1986), Vincent (Vincent, 1998), E-P method (Easterling and Peterson, 1995) and Bivariate test (Maronna and Yohai, 1978) were selected for break detection. Break detection is in all methods restricted to monthly data. Since we are dealing with daily relative humidity data, the amount of methods for break correction is reduced to MASH, ACMANT, Vincent, SPLIDHOM (Mestre et al., 2011), Percentile method (Stepanek, 2009). Information on the surrogate dataset will be given and the results in break detection and break correction in 2 different datasets (deterministic and deterministic + random changes + trend signals) are shown and discussed.

  20. The effect of relative humidity on germination of Sporangia of Phytophthora ramorum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sporangia of three isolates of P. ramorum representing three different clonal lineages were subjected to relative humidity (RH) levels between 80 and 100% for exposure periods ranging from 1 to 24 h at 20°C in darkness. Airtight snap-lid plastic containers (21.5 x 14.5 x 5 cm) were used as humidity ...

  1. Humidity sensing by carbon nanocones.

    PubMed

    Svåsand, Eldrid; Häberle, Patricio

    2014-05-01

    Carbon nano-structures, mainly nanotubes, have been explored in the past as sensing devices. In this report we have considered cones and discs (CNCs) subjected to acid treatment, dry oxidation and high temperature annealing, to study the modifications induced as they are used as sensing elements of varying relative humidity (RH). The relative humidity was varied in cycles of 30 min between 36% and 75%. Not strangely, the acid treated films displayed a much larger variation in resistance for the same difference in RH (16%). In the as-grown material, very small variations were detected among cycles under similar conditions. The changes induced in the sensors structures by the different preparation procedures were characterized by transmission electron microscopy (TEM) and Raman reflexion. These results were used to model their behaviour as RH sensors. PMID:24734591

  2. Short term change in relative humidity during the festival of Diwali in India

    NASA Astrophysics Data System (ADS)

    Ganguly, Nandita D.

    2015-07-01

    The changes in humidity levels during the Diwali festivities have been examined over a period of 13 years at three Indian metro cities: Ahmedabad, New Delhi and Kolkata. A small short term increase in relative humidity even in the absence of transport of humid air from Arabian Sea and Bay of Bengal has been observed. The relative humidity levels were found to be exceeding the ambient levels during night and lying below the ambient levels during morning hours, indicating an increase in the survival rates of viruses responsible for the transmission of viral infections, as well as triggering immune-mediated illnesses such as asthma during Diwali.

  3. Influence of fine water droplets to temperature and humidity

    NASA Astrophysics Data System (ADS)

    Hafidzal, M. H. M.; Hamzah, A.; Manaf, M. Z. A.; Saadun, M. N. A.; Zakaria, M. S.; Roslizar, A.; Jumaidin, R.

    2015-05-01

    Excessively dry air can cause dry skin, dry eyes and exacerbation of medical conditions. Therefore, many researches have been done in order to increase humidity in our environment. One of the ways is by using water droplets. Nowadays, it is well known in market stand fan equipped with water mister in order to increase the humidity of certain area. In this study, the same concept is applied to the ceiling fan. This study uses a model that combines a humidifier which functions as cooler, ceiling fan and scaled down model of house. The objective of this study is to analyze the influence of ceiling fan humidifier to the temperature and humidity in a house. The mechanism of this small model uses batteries as the power source, connected to the fan and the humidifier. The small water tank's function is to store and supply water to the humidifier. The humidifier is used to cool the room by changing water phase to fine water droplets. Fine water droplets are created from mechanism of the humidifier, which is by increasing the kinetic energy of water molecule using high frequency vibration that overcome the holding force between water molecules. Thus, the molecule of water will change to state of gas or mist. The fan is used to spread out the mist of water to surrounding of the room in order to enhance the humidity. Thermocouple and humidity meter are used to measure temperature and humidity in some period of times. The result shows that humidity increases and temperature decreases with time. This application of water droplet can be applied in the vehicles and engine in order to decrease the temperature.

  4. Humidity and Buildings. Technical Paper No. 188.

    ERIC Educational Resources Information Center

    Hutcheon, N. B.

    Modified and controlled relative humidity in buildings for certain occupancies is discussed. New criteria are used in determining the needs, desirability and problems associated with humidities in a building. Severe winter climate requires that special attention be given to the problems associated with increased indoor humidities during cold…

  5. Child mortality in a West African population protected with insecticide-treated curtains for a period of up to 6 years.

    PubMed Central

    Diallo, D. A.; Cousens, S. N.; Cuzin-Ouattara, N.; Nebié, I.; Ilboudo-Sanogo, E.; Esposito, F.

    2004-01-01

    OBJECTIVES: To determine the impact of insecticide-treated curtains (ITC) on all-cause child mortality (6-59 months) over a period of six years. To determine whether initial reductions in child mortality following the implementation of ITC are sustained over the longer term or whether "delayed" mortality occurs. METHODS: A rural population of ca 100 000 living in an area with high, seasonal Plasmodium falciparum transmission was studied in Burkina Faso. Annual censuses were conducted from 1993 to 2000 to measure child mortality. ITC to cover doors, windows, and eaves were provided to half the population in 1994 with the remainder receiving ITC in 1996. Curtains were re-treated or, if necessary, replaced annually. FINDINGS: Over six years of implementation of ITC, no evidence of the shift in child mortality from younger to older children was observed. Estimates of the reduction in child mortality associated with ITC ranged from 19% to 24%. CONCLUSIONS: In our population there was no evidence to suggest that initial reduction in child mortality associated with the introduction of insecticide-treated materials was subsequently compromised by a shift in child mortality to older-aged children. Estimates of the impact of ITC on child mortality in this population range from 19% to 24%. PMID:15042229

  6. West Indian Ocean variability and East African fish catch.

    PubMed

    Jury, M; McClanahan, T; Maina, J

    2010-08-01

    We describe marine climate variability off the east coast of Africa in the context of fish catch statistics for Tanzania and Kenya. The time series exhibits quasi-decadal cycles over the period 1964-2007. Fish catch is up when sea surface temperature (SST) and atmospheric humidity are below normal in the tropical West Indian Ocean. This pattern relates to an ocean Rossby wave in one phase of its east-west oscillation. Coastal-scale analyses indicate that northward currents and uplift on the shelf edge enhance productivity of East African shelf waters. Some of the changes are regulated by the south equatorial current that swings northward from Madagascar. The weather is drier and a salty layer develops in high catch years. While the large-scale West Indian Ocean has some impact on East African fish catch, coastal dynamics play a more significant role. Climatic changes are reviewed using 200 years of past and projected data. The observed warming trend continues to increase such that predicted SST may reach 30 degrees C by 2100 while SW monsoon winds gradually increase, according to a coupled general circulation model simulation with a gradual doubling of CO(2). PMID:20471674

  7. Studies of African wave disturbances with the GISS GCM

    NASA Technical Reports Server (NTRS)

    Druyan, Leonard M.; Hall, Timothy M.

    1994-01-01

    Simulations made with the general circulation model of the NASA/Goddard Institute for Space Studies (GISS GCM) run at 4 deg latitude by 5 deg longitude horizontal resolution are analyzed to determine the model's representation of African wave disturbances. Waves detected in the model's lower troposphere over northern Africa during the summer monsoon season exhibit realistic wavelengths of about 2200 km. However, power spectra of the meridional wind show that the waves propagate westward too slowly, with periods of 5-10 days, about twice the observed values. This sluggishness is most pronounced during August, consistent with simulated 600-mb zonal winds that are only about half the observed speeds of the midtropospheric jet. The modeled wave amplitudes are strongest over West Africa during the first half of the summer but decrease dramatically by September, contrary to observational evidence. Maximum amplitudes occur at realistic latitudes, 12 deg - 20 deg N, but not as observed near the Atlantic coast. Spectral analyses suggest some wave modulation of precipitation in the 5-8 day band, and compositing shows that precipitation is slightly enhanced east of the wave trough, coincident with southerly winds. Extrema of low-level convergence west of the wave troughs, coinciding with northerly winds, were not preferred areas for simulated precipitation, probably because of the drying effect of this advection, as waves were generally north of the humid zone. The documentation of African wave disturbances in the GISS GCM is a first step toward considering wave influences in future GCM studies of Sahel drought.

  8. Comparison of GPS-TEC with IRI-2012 TEC over African equatorial and low latitude regions during the period of 2012-2013

    NASA Astrophysics Data System (ADS)

    Tariku, Yekoye Asmare

    2015-10-01

    This paper presents the performance of the latest version of the International Reference Ionosphere (IRI-2012) model in estimating the Vertical Total Electron Content (VTEC) variation over equatorial and low latitude East Africa regions during the period of 2012-2013. This has been conducted by comparing the ground-based Global Positioning System (GPS) VTEC inferred from nine dual frequency GPS receivers installed at different regions in the continent. In this work, the diurnal, monthly and seasonal variation in the measured VTEC have been analyzed and compared with the VTEC obtained from IRI-2012 model. It is depicted that the lowest diurnal peaks of the modeled and measured VTEC values are observed in the June solstice months, whereas the highest values are observed in the equinoctial months. The variability of the diurnal GPS-VTEC is also found to be minimal nearly at 03:00 UT and maximal mostly between 09:00 and 14:00 UT. Moreover, the maximum and minimum monthly mean hourly measured VTEC values inferred from both the Arba Minch and Entebbe stations are observed in October and July, respectively. Similarly, the highest and the lowest seasonal mean hourly measured VTEC values are observed in the September equinox and in the June solstice, respectively. The model predictions generally follow the diurnal variations of the measured VTEC, with minimum value at predawn hours and maximum at noontime hours (10:00-13:00 UT). It has been shown that the model better estimates the diurnal VTEC values mostly just after midnight hours (00:00-03:00 UT). Good agreements between the modeled and measured monthly and seasonal mean hourly VTEC values obtained from Arba Minch station are also observed in the equinoctial months. But, for the Entebbe station, the modeled monthly and seasonal VTEC values are larger than the corresponding measured VTEC values by about 75% and 60%, respectively. In addition, there are large discrepancies observed between the diurnal measured and modeled

  9. African Aesthetics

    ERIC Educational Resources Information Center

    Abiodun, Rowland

    2001-01-01

    No single traditional discipline can adequately supply answers to the many unresolved questions in African art history. Because of the aesthetic, cultural, historical, and, not infrequently, political biases, already built into the conception and development of Western art history, the discipline of art history as defined and practiced in the West…

  10. Changes in northeast African hydrology and vegetation associated with Pliocene-Pleistocene sapropel cycles.

    PubMed

    Rose, Cassaundra; Polissar, Pratigya J; Tierney, Jessica E; Filley, Timothy; deMenocal, Peter B

    2016-07-01

    East African climate change since the Late Miocene consisted of persistent shorter-term, orbital-scale wet-dry cycles superimposed upon a long-term trend towards more open, grassy landscapes. Either or both of these modes of palaeoclimate variability may have influenced East African mammalian evolution, yet the interrelationship between these secular and orbital palaeoclimate signals remains poorly understood. Here, we explore whether the long-term secular climate change was also accompanied by significant changes at the orbital-scale. We develop northeast African hydroclimate and vegetation proxy data for two 100 kyr-duration windows near 3.05 and 1.75 Ma at ODP Site 967 in the eastern Mediterranean basin, where sedimentation is dominated by eastern Sahara dust input and Nile River run-off. These two windows were selected because they have comparable orbital configurations and bracket an important increase in East African C4 grasslands. We conducted high-resolution (2.5 kyr sampling) multiproxy biomarker, H- and C-isotopic analyses of plant waxes and lignin phenols to document orbital-scale changes in hydrology, vegetation and woody cover for these two intervals. Both intervals are dominated by large-amplitude, precession-scale (approx. 20 kyr) changes in northeast African vegetation and rainfall/run-off. The δ(13)Cwax values and lignin phenol composition record a variable but consistently C4 grass-dominated ecosystem for both intervals (50-80% C4). Precessional δDwax cycles were approximately 20-30‰ in peak-to-peak amplitude, comparable with other δDwax records of the Early Holocene African Humid Period. There were no significant differences in the means or variances of the δDwax or δ(13)Cwax data for the 3.05 and 1.75 Ma intervals studied, suggesting that the palaeohydrology and palaeovegetation responses to precessional forcing were similar for these two periods. Data for these two windows suggest that the eastern Sahara did not experience the

  11. Kunta Kinte's Struggle to be African

    ERIC Educational Resources Information Center

    Courlander, Harold

    1986-01-01

    This article reveals the differences between the character Kunta Kinte and the historical record concerning African males in the preslavery period. Kunta's non-African behaviors include displays of blind anger and rage, prudishness, and actions unknown in his Mandinka culture. These represent the many misrepresentations and ambiguities in Alex…

  12. Characterization of spacecraft humidity condensate

    NASA Technical Reports Server (NTRS)

    Muckle, Susan; Schultz, John R.; Sauer, Richard L.

    1994-01-01

    When construction of Space Station Freedom reaches the Permanent Manned Capability (PMC) stage, the Water Recovery and Management Subsystem will be fully operational such that (distilled) urine, spent hygiene water, and humidity condensate will be reclaimed to provide water of potable quality. The reclamation technologies currently baselined to process these waste waters include adsorption, ion exchange, catalytic oxidation, and disinfection. To ensure that the baseline technologies will be able to effectively remove those compounds presenting a health risk to the crew, the National Research Council has recommended that additional information be gathered on specific contaminants in waste waters representative of those to be encountered on the Space Station. With the application of new analytical methods and the analysis of waste water samples more representative of the Space Station environment, advances in the identification of the specific contaminants continue to be made. Efforts by the Water and Food Analytical Laboratory at JSC were successful in enlarging the database of contaminants in humidity condensate. These efforts have not only included the chemical characterization of condensate generated during ground-based studies, but most significantly the characterization of cabin and Spacelab condensate generated during Shuttle missions. The analytical results presented in this paper will be used to show how the composition of condensate varies amongst enclosed environments and thus the importance of collecting condensate from an environment close to that of the proposed Space Station. Although advances were made in the characterization of space condensate, complete characterization, particularly of the organics, requires further development of analytical methods.

  13. Association of Temperature and Humidity with Trauma Deaths

    PubMed Central

    Ranandeh Kalankesh, Laleh; Mansouri, Fatemeh; Khanjani, Narges

    2015-01-01

    Background: Few studies worldwide have shown that climate factors such as temperature and humidity may contribute to injuries and sudden death. However, to the best of our knowledge no studies have been conducted on climate and traumatic deaths in Iran. Objectives: The aim of this study was to investigate the relationship between temperature and humidity and trauma deaths in Kerman, Iran. Materials and Materials: In this study, data of all trauma deaths from March 2006 to February 2011 were collected from the Kerman Health Ministry and categorized by causes. Trauma deaths were extracted and matched with data regarding temperature and humidity obtained from the Kerman Meteorology Office during the same time period. Negative binomial regression and Spearman correlation analysis were used to analyze the data using STATA10 and MiniTab16. Results: The findings of this study showed that the overall mortality caused by trauma is higher in the warm season. The highest correlation between mortality and temperature was seen in ages over 60 years (r = 0.301, P = 0.020) in trauma deaths and was statistically significant. An inverse significant correlation was observed between the incidence of trauma deaths and humidity and was highest in the over 60-year age group (r = -0.336, P = 0.009). The regression results also revealed an inverse significant relationship between humidity and trauma deaths in the over 60-year age group. Conclusions: High temperatures and low humidity increased the risk of trauma deaths in our study. However, more studies are needed to document this. PMID:26839859

  14. Relative Humidity Measurement Assurance Program Results

    NASA Technical Reports Server (NTRS)

    Cerezo, Miguel

    1993-01-01

    During the summer of 1992, the National Conference of Standards Laboratories sponsored a relative humidity measurement assurance program (RHMAP) whose purpose was to enable each participating center to assess the quality of relative humidity calibrations being performed by their respective standards laboratories. This paper presents the data which was submitted by the participants during the first round of the program and shows the multi-laboratory comparisons of the 20%, 50%, and 80% relative humidity meaurements performed.

  15. Propagation of biases in humidity in the estimation of global irrigation water

    NASA Astrophysics Data System (ADS)

    Masaki, Y.; Hanasaki, N.; Takahashi, K.; Hijioka, Y.

    2015-07-01

    data, the uncertainty ranges of irrigation water demand across the five GCMs were successfully reduced from 282.9 to 167.0 km3 yr-1 for the present period, and from 381.1 to 214.8 km3 yr-1 for the future period (RCP8.5, 2070-2099). Although different GHMs have different sensitivities to atmospheric humidity because different types of potential evapotranspiration formulae are implemented in them, bias correction of the humidity should be applied to forcing data, particularly for the evaluation of evapotranspiration and irrigation water.

  16. Obesity and African Americans

    MedlinePlus

    ... Data > Minority Population Profiles > Black/African American > Obesity Obesity and African Americans African American women have the ... ss6304.pdf [PDF | 3.38MB] HEALTH IMPACT OF OBESITY More than 80 percent of people with type ...

  17. Trajectory Simulations of Upper Tropospheric Humidity

    NASA Technical Reports Server (NTRS)

    Dessler, A. E.; Schoeberl, M. R.; Sherwood, S. C.

    1999-01-01

    We present comparisons of simulations of upper tropospheric humidity at 215 and 146 hPa with satellite measurements. Our model uses diabatic trajectories to advect water vapor from an initial condition of 100% relative humidity to the final state. The model does not allow parcels' relative humidity to exceed 100%, and in this way crudely incorporates condensation. We find that this simple model does a good job of simulating the observations. Sensitivity studies suggest that one must have realistic wind velocities in order to accurately simulate the humidity distribution; microphysical parameterizations seem to be less important. Comparisions between simulations using UKMO and NCEP horizontal winds will be discussed.

  18. CMOS integration of inkjet-printed graphene for humidity sensing

    NASA Astrophysics Data System (ADS)

    Santra, S.; Hu, G.; Howe, R. C. T.; de Luca, A.; Ali, S. Z.; Udrea, F.; Gardner, J. W.; Ray, S. K.; Guha, P. K.; Hasan, T.

    2015-11-01

    We report on the integration of inkjet-printed graphene with a CMOS micro-electro-mechanical-system (MEMS) microhotplate for humidity sensing. The graphene ink is produced via ultrasonic assisted liquid phase exfoliation in isopropyl alcohol (IPA) using polyvinyl pyrrolidone (PVP) polymer as the stabilizer. We formulate inks with different graphene concentrations, which are then deposited through inkjet printing over predefined interdigitated gold electrodes on a CMOS microhotplate. The graphene flakes form a percolating network to render the resultant graphene-PVP thin film conductive, which varies in presence of humidity due to swelling of the hygroscopic PVP host. When the sensors are exposed to relative humidity ranging from 10-80%, we observe significant changes in resistance with increasing sensitivity from the amount of graphene in the inks. Our sensors show excellent repeatability and stability, over a period of several weeks. The location specific deposition of functional graphene ink onto a low cost CMOS platform has the potential for high volume, economic manufacturing and application as a new generation of miniature, low power humidity sensors for the internet of things.

  19. CMOS integration of inkjet-printed graphene for humidity sensing.

    PubMed

    Santra, S; Hu, G; Howe, R C T; De Luca, A; Ali, S Z; Udrea, F; Gardner, J W; Ray, S K; Guha, P K; Hasan, T

    2015-01-01

    We report on the integration of inkjet-printed graphene with a CMOS micro-electro-mechanical-system (MEMS) microhotplate for humidity sensing. The graphene ink is produced via ultrasonic assisted liquid phase exfoliation in isopropyl alcohol (IPA) using polyvinyl pyrrolidone (PVP) polymer as the stabilizer. We formulate inks with different graphene concentrations, which are then deposited through inkjet printing over predefined interdigitated gold electrodes on a CMOS microhotplate. The graphene flakes form a percolating network to render the resultant graphene-PVP thin film conductive, which varies in presence of humidity due to swelling of the hygroscopic PVP host. When the sensors are exposed to relative humidity ranging from 10-80%, we observe significant changes in resistance with increasing sensitivity from the amount of graphene in the inks. Our sensors show excellent repeatability and stability, over a period of several weeks. The location specific deposition of functional graphene ink onto a low cost CMOS platform has the potential for high volume, economic manufacturing and application as a new generation of miniature, low power humidity sensors for the internet of things. PMID:26616216

  20. CMOS integration of inkjet-printed graphene for humidity sensing

    PubMed Central

    Santra, S.; Hu, G.; Howe, R. C. T.; De Luca, A.; Ali, S. Z.; Udrea, F.; Gardner, J. W.; Ray, S. K.; Guha, P. K.; Hasan, T.

    2015-01-01

    We report on the integration of inkjet-printed graphene with a CMOS micro-electro-mechanical-system (MEMS) microhotplate for humidity sensing. The graphene ink is produced via ultrasonic assisted liquid phase exfoliation in isopropyl alcohol (IPA) using polyvinyl pyrrolidone (PVP) polymer as the stabilizer. We formulate inks with different graphene concentrations, which are then deposited through inkjet printing over predefined interdigitated gold electrodes on a CMOS microhotplate. The graphene flakes form a percolating network to render the resultant graphene-PVP thin film conductive, which varies in presence of humidity due to swelling of the hygroscopic PVP host. When the sensors are exposed to relative humidity ranging from 10–80%, we observe significant changes in resistance with increasing sensitivity from the amount of graphene in the inks. Our sensors show excellent repeatability and stability, over a period of several weeks. The location specific deposition of functional graphene ink onto a low cost CMOS platform has the potential for high volume, economic manufacturing and application as a new generation of miniature, low power humidity sensors for the internet of things. PMID:26616216

  1. Technical Highlight: Evaluation of Humidity Control Options in Hot-Humid Climate Homes

    SciTech Connect

    none,

    2011-12-01

    This technical highlight describes NREL research to analyze the indoor relative humidity in three home types in the hot-humid climate zone, and examine the impacts of various dehumidification equipment and controls.

  2. The Chew Bahir Project, southern Ethiopia: Reconstructing East African palaeoenvironments in the source region of modern man

    NASA Astrophysics Data System (ADS)

    Foerster, V. E.; Chew Bahir Science Team

    2011-12-01

    Chew Bahir is a tectonically bounded basin in the southern part of the Main Ethiopian Rift and in close proximity to the Omo valley, which contains some of the oldest known early modern human sites. As East African palaeoenvironments are highly variable and marked by extreme fluctuations in moisture availability, this in turn bears far reaching implications for the life, evolution and most notably for the expansion of Homo sapiens beyond the limits of the African continent. This study is a prerequisite for the ICDP- Hominin Sites And Paleolakes Drilling Project and part of the CRC-806 "Our way to Europe". The Chew Bahir Project will provide fundamental data to reconstruct late Quaternary East African environments including the timing, amplitude, synchronicity and abruptness of dry-wet-dry cycles and focuses on the interaction between those rapid climate shifts and their influence on the biosphere. This poster presents results from six cores (9-18m depth) from a NW-SE transect across the Chew Bahir basin that have recorded the climatic history of the past 45 ka and therewith can potentially elucidate those highly variable East African palaeoenvironments with emphasis on the last of the wet periods, the African Humid Period (AHP). Based on a series of multi-proxy analyses, comprising geochemical, physical and biological indicators as well as AMS 14C dates, it becomes obvious that the Chew Bahir responds decidedly sensitive towards even minor climatic fluctuations on millennial to even centennial timescales. Therefore, the Chew Bahir represents a unique site to reveal the impact of timing and mechanisms of local, regional and global climate events on the key region for humankind.

  3. Boundaries for Biofilm Formation: Humidity and Temperature

    PubMed Central

    Else, Terry Ann; Pantle, Curtis R.; Amy, Penny S.

    2003-01-01

    Environmental conditions which define boundaries for biofilm production could provide useful ecological information for biofilm models. A practical use of defined conditions could be applied to the high-level nuclear waste repository at Yucca Mountain. Data for temperature and humidity conditions indicate that decreases in relative humidity or increased temperature severely affect biofilm formation on three candidate canister metals. PMID:12902302

  4. Temperature and humidity within the clothing microenvironment.

    PubMed

    Sullivan, P J; Mekjavić, I B

    1992-03-01

    The present study investigates clothing microenvironment conditions that may develop during prolonged exposure of workers to a hot environment. Five subjects were exposed to a linear increase in ambient temperature from 20-40 degrees C over a 90-min period, and then remained at 40 degrees C for an additional 90 min. During the exposures, subjects were clad in four types of helicopter personnel suits (Gore-Tex, Cotton Ventile, Nomex/Insulite, and Nomex/Neoprene), incorporating both dry-suit and wet-suit designs. Continuous assessment was made of skin temperature, rectal temperature, and of microenvironment temperature, relative humidity, and vapor pressure (T mu, RH mu, and VP mu) 8 mm from the surface of the skin. Results indicate that although microenvironment temperatures were similar among suits and slightly lower than that of the environment, the RH mu and VP mu were much greater than those of the ambient air. The Nomex/Insulite and Nomex/Neoprene suits showed the highest VP mu, of which only the Nomex/Insulite resulted in significantly greater increases in rectal temperature, likely due to complete covering of the body with the impermeable insulite component. The present study demonstrates the need to discern between the ambient conditions and the conditions encountered next to the skin when protective clothing is worn. PMID:1567319

  5. Temperature humidity index scenarios in the Mediterranean basin

    NASA Astrophysics Data System (ADS)

    Segnalini, M.; Bernabucci, U.; Vitali, A.; Nardone, A.; Lacetera, N.

    2013-05-01

    The study was undertaken to describe the temperature humidity index (THI) dynamics over the Mediterranean basin for the period 1971-2050. The THI combines temperature and humidity into a single value, and has been widely used to predict the effects of environmental warmth in farm animals. The analysis was based on daily outputs of the temperature and relative humidity from the Max Planck Institute data using the Intergovernmental Panel on Climate Change Special Report Emission Scenario A1B. Data revealed a gradual increase of both annual and seasonal THI during the period under investigation and a strong heterogeneity of the Mediterranean area. In particular, the analysis indicated that Spain, southern France and Italy should be expected to undergo the highest THI increase, which in the last decade under study (2041-2050) will range between 3 and 4 units. However, only during summer months the area presents characteristics indicating risk of thermal (heat) stress for farm animals. In this regard, scenario maps relative to the summer season suggested an enlargement of the areas in the basin where summer THI values will likely cause thermal discomfort in farm animals. In conclusion, the study indicated that the Mediterranean basin is likely to undergo THI changes, which may aggravate the consequences of hot weather on animal welfare, performances, health and survival and may help farmers, nutritionists, veterinarians, and policy-makers to develop appropriate adaptation strategies to limit consequences of climate change for the livestock sector in the Mediterranean countries.

  6. Temperature humidity index scenarios in the Mediterranean basin.

    PubMed

    Segnalini, M; Bernabucci, U; Vitali, A; Nardone, A; Lacetera, N

    2013-05-01

    The study was undertaken to describe the temperature humidity index (THI) dynamics over the Mediterranean basin for the period 1971-2050. The THI combines temperature and humidity into a single value, and has been widely used to predict the effects of environmental warmth in farm animals. The analysis was based on daily outputs of the temperature and relative humidity from the Max Planck Institute data using the Intergovernmental Panel on Climate Change Special Report Emission Scenario A1B. Data revealed a gradual increase of both annual and seasonal THI during the period under investigation and a strong heterogeneity of the Mediterranean area. In particular, the analysis indicated that Spain, southern France and Italy should be expected to undergo the highest THI increase, which in the last decade under study (2041-2050) will range between 3 and 4 units. However, only during summer months the area presents characteristics indicating risk of thermal (heat) stress for farm animals. In this regard, scenario maps relative to the summer season suggested an enlargement of the areas in the basin where summer THI values will likely cause thermal discomfort in farm animals. In conclusion, the study indicated that the Mediterranean basin is likely to undergo THI changes, which may aggravate the consequences of hot weather on animal welfare, performances, health and survival and may help farmers, nutritionists, veterinarians, and policy-makers to develop appropriate adaptation strategies to limit consequences of climate change for the livestock sector in the Mediterranean countries. PMID:22850789

  7. Africans in America.

    ERIC Educational Resources Information Center

    Hart, Ayanna; Spangler, Earl

    This book introduces African-American history and culture to children. The first Africans in America came from many different regions and cultures, but became united in this country by being black, African, and slaves. Once in America, Africans began a long struggle for freedom which still continues. Slavery, the Civil War, emancipation, and the…

  8. African Outreach Workshop 1974.

    ERIC Educational Resources Information Center

    Schmidt, Nancy J.

    This report discusses the 1974 African Outreach Workshop planned and coordinated by the African Studies Program at the University of Illinois at Urbana-Champaign. Its major aim was to assist teachers in developing curriculum units on African using materials available in their local community. A second aim was for the African Studies Program to…

  9. 40 CFR 89.326 - Engine intake air humidity measurement.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 20 2011-07-01 2011-07-01 false Engine intake air humidity measurement... Test Equipment Provisions § 89.326 Engine intake air humidity measurement. (a) Humidity conditioned air supply. Air that has had its absolute humidity altered is considered humidity- conditioned air. For...

  10. 40 CFR 89.326 - Engine intake air humidity measurement.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 21 2012-07-01 2012-07-01 false Engine intake air humidity measurement... Test Equipment Provisions § 89.326 Engine intake air humidity measurement. (a) Humidity conditioned air supply. Air that has had its absolute humidity altered is considered humidity- conditioned air. For...

  11. 40 CFR 89.326 - Engine intake air humidity measurement.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 20 2014-07-01 2013-07-01 true Engine intake air humidity measurement... Test Equipment Provisions § 89.326 Engine intake air humidity measurement. (a) Humidity conditioned air supply. Air that has had its absolute humidity altered is considered humidity- conditioned air. For...

  12. 40 CFR 89.326 - Engine intake air humidity measurement.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 21 2013-07-01 2013-07-01 false Engine intake air humidity measurement... Test Equipment Provisions § 89.326 Engine intake air humidity measurement. (a) Humidity conditioned air supply. Air that has had its absolute humidity altered is considered humidity- conditioned air. For...

  13. 40 CFR 89.326 - Engine intake air humidity measurement.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Engine intake air humidity measurement... Test Equipment Provisions § 89.326 Engine intake air humidity measurement. (a) Humidity conditioned air supply. Air that has had its absolute humidity altered is considered humidity- conditioned air. For...

  14. Toward a New Generation of Photonic Humidity Sensors

    PubMed Central

    Kolpakov, Stanislav A.; Gordon, Neil T.; Mou, Chengbo; Zhou, Kaiming

    2014-01-01

    This review offers new perspectives on the subject and highlights an area in need of further research. It includes an analysis of current scientific literature mainly covering the last decade and examines the trends in the development of electronic, acoustic and optical-fiber humidity sensors over this period. The major findings indicate that a new generation of sensor technology based on optical fibers is emerging. The current trends suggest that electronic humidity sensors could soon be replaced by sensors that are based on photonic structures. Recent scientific advances are expected to allow dedicated systems to avoid the relatively high price of interrogation modules that is currently a major disadvantage of fiber-based sensors. PMID:24577524

  15. Changing rainfall and humidity within Southeast Texas.

    PubMed

    Smith, Robert Kennedy

    2015-01-01

    Southeast Texas houses a precipitation transition zone between drier conditions to the North and West and some of the wettest parts of the continental U.S. to the East. The Region has seen an increase in its reported normal annual precipitation totals in recent decades. In order to determine if the additional rainfall has been influenced by warming temperatures or is within the variability of the State's long-term drought cycles, several analyses were performed on historical climate data. The analyses answered several questions: Have global and regional climate change models predicted precipitation increases in Southeast Texas and are future increases expected? Do historical monthly precipitation totals at various sites in the region provide clear trends of wetter conditions that can be discerned from long-term drought cycles? Are rainfall patterns changing with less frequent, heavier rain events? Do the reported increases in annual rainfall actually lead to wetter conditions in the region? Climate models have not predicted larger annual average precipitation totals nor do they forecast increases for Southeast Texas. While recent decades may have seen more rain relative to earlier periods, a combined analysis of observation stations across different parts of the Region shows that long-term trends are dependent on when the data is selected relative to a drought cycle. While some stations show larger amounts of rain falling during fewer days, these trends do not hold across all periods. An examination of hourly data does not show an increase in extreme rainfall events or a decrease in the number of hours during which rain has fallen. Even though rainfall has not decreased, average relative humidity has fallen. This suggests that the area is drying even with steady or increasing amounts of rain. PMID:26322255

  16. African diatom palaeoecology and biostratigraphy

    NASA Astrophysics Data System (ADS)

    Gasse, F.; Fourtanier, E.

    This paper illustrates the different types of information which can be deduced from African diatoms studies. The first section is devoted to the reconstruction of palaeoenvironments. The accuracy of ecological data (estimates of ecological variables e.g. types of habitats, water chemistry…) depends on the times scale and on the spatial scale considered: short-term environments in a given waterbody, environmental evolution during individual humid episodes considered locally or regionally, long-term changes in diatom flora induced by major climatic tendencies at a regional or continental scale. One then summarizes our present state of knowledge in diatom biostratigraphy in Africa. Several centric taxa, belonging to the genera Aulacoseira, Mesodictyon, Cyclotella, Stephanodiscus and Cyclostephanos appear to have limited stratigraphical ranges and to be good chronological markers.

  17. Synthesis, characterization, and humidity sensing of metallophtalocyanines

    NASA Astrophysics Data System (ADS)

    Chakane, Sanjay D. S.; Jain, Shilpa; Bhoraskar, S. V.

    2001-03-01

    Metallophthalocyanines synthesized for different metals such as Ni, Cr, Ag, Mg, Cu, Cd, Al, etc by chemical methods were characterized with FTIR, UV etc. Sensing of humidity and different gases such as Nox, H2, O2, CO2, N2, ammonia, alcohol vapours etc were checked with 2-probe technique with monitoring change in resistance change. These samples have excellent stability against heat, light, air, and hence it has considerable attention for environmentally stable gas sensor. The electrical property of these samples were investigated at room temperature and at normal atmospheric pressure from low to 98% relative Humidity. It was observed that these samples shows good response and recovery for humidity sensing.

  18. Surface Temperature Humidity Reference System Handbook - November 2005

    SciTech Connect

    MT Ritsche

    2005-11-30

    The Surface Temperature and Humidity Reference (SURTHREF) system is intended to provide accurate reference values of ambient temperature and relative humidity for comparison with radiosonde prelaunch values.

  19. A Record of Early to Middle Holocene Hydroclimate Variability from the West African Sahel

    NASA Astrophysics Data System (ADS)

    McIntosh, R.; Douglas, P. M.; Warren, C.; Meyers, S. R.; Coutros, P.; Park, D. P.

    2011-12-01

    The African Humid Period (ca. 14.8 to 5.5 ka) is an interval of wet climates across northwest Africa, with evidence for widespread lake basins and savannah vegetation in areas that are now desert. There are few high-resolution continental records of hydrologic variability during the African humid period however. In particular, it remains uncertain how periods of north Atlantic climate variability were expressed in northwest Africa. We present results from a 5.4 meter sediment core from Lake Fati in northern Mali (16.29° N, 3.71° W), which represents the first lake sediment core from the western Sahel. The Lake Fati core contains a continuous record of lake mud from 10.43 to 4.66 kyr BP. Centimeter scale XRF scanning indicates strong covariation between iron, calcium, manganese and phosphorous abundance due to enrichment of these elements during periods of enhanced deposition of authigenic siderite. Preliminary oxygen isotope measurements indicate that authigenic siderite δ18O values are positively correlated with Fe counts, suggesting that siderite deposition increased during drier periods with greater evaporation of lake waters. These drying events occurred on decadal to centennial time scales, with higher-frequency variability during the early Holocene. Peaks in zirconium and titanium abundance coincide with some of the inferred dry periods, suggesting that deposition of aeolian silt coincided with periods of increased evaporation of lake water. A roughly 30 year interval of sand deposition at ~8.33 kyr BP suggests major drying and activation of aeolian sand deposition. This abrupt climate change could be related to the 8.2 ka event in the North Atlantic; further efforts to refine the sediment core age model will constrain the relationship of this rapid drying to abrupt climate change in the North Atlantic. Aluminum and silicon counts co-vary for much of the lake Fati record, and are related to input of terrigenous sediment, primarily during seasonal flooding

  20. How factoring in humidity adds value

    SciTech Connect

    Berlin, G. )

    1994-09-01

    Humidity plays a major role in health, comfort, and production. This article is a brief overview of the technologies available and a detailed explanation of how to calculate humidification loads. The problems caused by dry air vary from one building to another and from one area to another. But basically, there are three major problem types: static electricity, poor moisture stability, health and comfort problems. In today's business offices, static electricity can disrupt operations and increase operating costs. In printing facilities, low humidity causes poor ink registration. Also, sheets of paper stick together and jam machines, wasting time and paper. In computer rooms and data processing areas, dry air leads to static electric discharges that cause circuit board failure, dust buildup on heads, and storage tape breakage. Moisture stability impacts industrial processes and the materials they use. In many cases, product and material deterioration is directly related to moisture fluctuations and lack of humidity control. Books, antiques, paper, wood and wood products, and fruits and vegetables are a few items that can be ruined by low or changing humidity. The health impact of low humidity shows up in dry nasal and thread membranes, dry and itchy skin, and irritated eyes. For employees, this means greater susceptibility to colds and other viral infections. The results is higher absenteeism when humidity is low, which translates into lost productivity and profits.

  1. Apparatus and methods for humidity control

    NASA Technical Reports Server (NTRS)

    Dinauer, William R. (Inventor); Otis, David R. (Inventor); El-Wakil, Mohamed M. (Inventor); Vignali, John C. (Inventor); Macaulay, Philip D. (Inventor)

    1994-01-01

    Apparatus is provided which controls humidity in a gas. The apparatus employs a porous interface that is preferably a manifolded array of stainless steel tubes through whose porous surface water vapor can pass. One side of the porous interface is in contact with water and the opposing side is in contact with gas whose humidity is being controlled. Water vapor is emitted from the porous surface of the tubing into the gas when the gas is being humidified, and water vapor is removed from the gas through the porous surfaces when the gas is being dehumidified. The temperature of the porous interface relative to the gas temperature determines whether humidification or dehumidification is being carried out. The humidity in the gas is sensed and compared to the set point humidity. The water temperature, and consequently the porous interface temperature, are automatically controlled in response to changes in the gas humidity level above or below the set point. Any deviation from the set point humidity is thus corrected.

  2. Effects of Temperature and Humidity on Major League Baseballs

    NASA Astrophysics Data System (ADS)

    Gerstman, Victoria; Raue, Brian

    2003-11-01

    In a study inspired by the famous humidor of the Colorado Rockies of Major League Baseball, we have measured the effects of temperature and humidity on the elasticity of official Major League baseballs. The elasticity, e, also referred to as the coefficient of restitution (COR), of the baseballs was determined by dropping the balls from a fixed height onto a concrete floor and determining the speed of the ball after the initial impact. Corrections for air drag were made to the measured COR. Measurements were done for baseballs stored under a wide variety of conditions that included storage in the freezer compartment of a household refrigerator, storage in an 80^rcC oven with varying humidity conditions, and storage in a crude humidor. The balls were tested over a period of several hours after removal to nominal conditions. Our results show a linear increase of the COR with increasing temperature, as well as a nearly linear decrease in the COR as water mass is increased. Using the results of our measurements, we have determined the effects of temperature and humidity on batted-ball speeds and flight distances at the Rockies' home field.

  3. Corynebacterial pneumonia in an African hedgehog.

    PubMed

    Raymond, J T; Williams, C; Wu, C C

    1998-04-01

    A 3-mo-old, male African hedgehog (Atelerix albiventris) was anorectic and lethargic for a period of 3 days prior to death. Necropys revealed lungs that were diffusely firm, dark red, and dorsally adhered by fibrinous tags to the pericardial sac. Histopathology revealed necrosuppurative bronchopneumonia with pulmonary abscesses and suppurative pericarditis and myocarditis. A Corynebacterium sp. was isolated from the lungs. We believe this is the first reported case of corynebacterial pneumonia in an African hedgehog. PMID:9577794

  4. The timing of alluvial sedimentation and floodplain formation in the lowland humid tropics of Ghana, Sierra Leone and western Kalimantan (Indonesian Borneo)

    NASA Astrophysics Data System (ADS)

    Thorp, Martin; Thomas, Michael

    1992-04-01

    Temporal patterns in floodplain genesis and alluvial sedimentation in lowlands tropical rain forest zones of Ghana, Sierra Leone and western Kalimantan (Indonesian Borneo) based upon 14C age determinations are described. Alluvial low terraces or buried sediments in West Africa yielded ages of 36-21 ka. In west Kalimantan a widespread episode of alluviation has yielded dates of 54-51 ka. The 20-13 ka interval was characterised by channel incision with valley floor erosion and neither region records sedimentation. Holocene alluvial sedimentation and floodplain construction in West Africa occurred during two temporal intervals: 10-7 ka and 4 ka to present and in western Kalimantan in response to early Holocene sea level rise followed by late Holocene regression and coastal outgrowth. The clustering of 14C dates closely corresponds to regional lake level fluctuations and vegetational changes and to global indications of climatic change. We propose that periods of more frequent episodes of accelerated floodplain erosion and reconstitution, channel morpho-sedimentary activity and alluvial accumulation (1) are responses to interstadial and interglacial periods of higher precipitation following intervening periods of cooler and drier conditions; and (2) may be synchronous during the last 60 ka throughout the African and Asian inner humid lowland tropics.

  5. The Russian National Standard of Gases Humidity and Traceability System of Humidity Measurements

    NASA Astrophysics Data System (ADS)

    Dubovikov, N. I.; Podmurnaya, O. A.; Skryabikov, N. P.; Sokov, I. A.; Vinge, A. F.

    2016-05-01

    The Russian national humidity standard of gases has been modernized in order to increase the number of reproducible quantities of humidity (relative humidity, dew/frost-point temperature, mole fraction) and to extend the humidity and operating temperature ranges. The basis of the standard comprises two humidity generators with operating temperature ranges from 5 ^{circ }hbox {C} to 90 ^{circ }hbox {C} and from -60 ^{circ }hbox {C} to 15 ^{circ }hbox {C}. The common working range (from 5 ^{circ }hbox {C} to 15 ^{circ }hbox {C}) allows comparison of the generators. The generators use the two-pressure method to generate humid gas defined in terms of the relative humidity (from 5 %rh to 98 %rh at temperatures from 90 ^{circ }hbox {C} to -60 ^{circ }hbox {C}) and the one-pressure (or phase equilibrium) method to generate humid gas defined in terms of the vapor mole fraction (from 0.6 ppm to 700× 103 ppm) and dew/frost-point temperature (from -79 ^{circ }hbox {C} to 90 ^{circ }hbox {C}). The expanded uncertainty in the relative humidity is no more than 0.2 %rh, no more than 1.2 % in the vapor mole fraction, and no more than 0.12 ^{circ }hbox {C} in the dew/frost-point temperature. The ordinary hygrometers are traceable to the national primary standard in accordance with the state hierarchical chain for measuring means of gas humidity. The state hierarchical chain consists of three branches for means of measurements: (a) mole fraction, (b) dew/frost-point temperature, and (c) relative humidity with each branch represented as the scheme: primary standard-secondary standard-working standard-ordinary hygrometer. Calibration and verification of working standards and ordinary hygrometers, and their traceability to the primary standard use methods of (i) direct measurements, (ii) direct comparison, or (iii) comparison with a comparator.

  6. Black African Traditional Mathematics

    ERIC Educational Resources Information Center

    Zaslavsky, Claudia

    1970-01-01

    Discusses the traditional number systems and the origin of the number names used by several African peoples living south of the Sahara. Also included are limitations in African mathematical development, and possible topics for research. (RP)

  7. Humidity effects on wire insulation breakdown strength.

    SciTech Connect

    Appelhans, Leah

    2013-08-01

    Methods for the testing of the dielectric breakdown strength of insulation on metal wires under variable humidity conditions were developed. Two methods, an ASTM method and the twisted pair method, were compared to determine if the twisted pair method could be used for determination of breakdown strength under variable humidity conditions. It was concluded that, although there were small differences in outcomes between the two testing methods, the non-standard method (twisted pair) would be appropriate to use for further testing of the effects of humidity on breakdown performance. The dielectric breakdown strength of 34G copper wire insulated with double layer Poly-Thermaleze/Polyamide-imide insulation was measured using the twisted pair method under a variety of relative humidity (RH) conditions and exposure times. Humidity at 50% RH and below was not found to affect the dielectric breakdown strength. At 80% RH the dielectric breakdown strength was significantly diminished. No effect for exposure time up to 140 hours was observed at 50 or 80%RH.

  8. 40 CFR 91.310 - Engine intake air humidity measurement.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 21 2012-07-01 2012-07-01 false Engine intake air humidity measurement... Provisions § 91.310 Engine intake air humidity measurement. This section refers to engines which are supplied... air, the ambient testcell humidity measurement may be used. (a) Humidity conditioned air supply....

  9. 40 CFR 91.310 - Engine intake air humidity measurement.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 20 2014-07-01 2013-07-01 true Engine intake air humidity measurement... Provisions § 91.310 Engine intake air humidity measurement. This section refers to engines which are supplied... air, the ambient testcell humidity measurement may be used. (a) Humidity conditioned air supply....

  10. 40 CFR 91.310 - Engine intake air humidity measurement.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Engine intake air humidity measurement... Provisions § 91.310 Engine intake air humidity measurement. This section refers to engines which are supplied... air, the ambient testcell humidity measurement may be used. (a) Humidity conditioned air supply....

  11. 40 CFR 91.310 - Engine intake air humidity measurement.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 20 2011-07-01 2011-07-01 false Engine intake air humidity measurement... Provisions § 91.310 Engine intake air humidity measurement. This section refers to engines which are supplied... air, the ambient testcell humidity measurement may be used. (a) Humidity conditioned air supply....

  12. 40 CFR 91.310 - Engine intake air humidity measurement.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 21 2013-07-01 2013-07-01 false Engine intake air humidity measurement... Provisions § 91.310 Engine intake air humidity measurement. This section refers to engines which are supplied... air, the ambient testcell humidity measurement may be used. (a) Humidity conditioned air supply....

  13. The African Connection

    ERIC Educational Resources Information Center

    Oguntoyinbo, Lekan

    2012-01-01

    From student and faculty exchanges to joint research projects, U.S. universities maintain a broad spectrum of collaborative relationships with African universities. It's unclear how many U.S. colleges and universities have partnerships with African universities. The African Studies Association, an organization of scholars, doesn't keep that kind…

  14. Silver Doped Titanium Dioxide Humidity Sensor

    NASA Astrophysics Data System (ADS)

    Hooshiar Zare, Ali; Mohammadi, Somayye

    2011-02-01

    The effect of silver doping on the sensitivity, dynamic range and the response time of a titanium dioxide-based resistive humidity sensor is studied. Sample pallets were prepared by sintering the dry pressed samples at 900°C in air. Silver was added to the ceramic raw material in the form of AgNO3 which was decomposed during the sintering process. Large area silver electrodes were deposited on the sintered disks by paste printing. The resistance and the response time of the various pallets containing different additive levels were measured at relative humidity range of 4-100%. Silver doping, substantially increased the sensitivity to the ambient humidity. Moreover, it resulted in faster responses; the response time of the silver added pallets were about four times shorter than the pure ones.

  15. Humidity Dependent Extinction of Clay Aerosols

    NASA Astrophysics Data System (ADS)

    Greenslade, M. E.; Attwood, A. R.

    2010-12-01

    Aerosols play an important role in the Earth’s radiative balance by directly scattering and absorbing radiation. The magnitude of aerosol forcing can be altered by changes in relative humidity which cause aerosol size, shape and refractive index to vary. To quantify these effects, a custom cavity ring down instrument operated at 532 nm with two sample channels measures aerosols extinction under dry conditions and at elevated humidity. The optical growth, fRH(ext), is determined as a ratio of the extinction cross section at high relative humidity to that under dry conditions. Three key clay components of mineral dust and mixtures of clay components with ammonium sulfate are investigated using this method. Experimentally obtained optical growth is compared with physical growth factors from the literature and our work determined using several different techniques. Further, Mie theory calculations based on published optical constants are compared with experimental results. Differences between theory and experiment will be discussed.

  16. Lanthanide-halide based humidity indicators

    DOEpatents

    Beitz, James V.; Williams, Clayton W.

    2008-01-01

    The present invention discloses a lanthanide-halide based humidity indicator and method of producing such indicator. The color of the present invention indicates the humidity of an atmosphere to which it is exposed. For example, impregnating an adsorbent support such as silica gel with an aqueous solution of the europium-containing reagent solution described herein, and dehydrating the support to dryness forms a substance with a yellow color. When this substance is exposed to a humid atmosphere the water vapor from the air is adsorbed into the coating on the pore surface of the silica gel. As the water content of the coating increases, the visual color of the coated silica gel changes from yellow to white. The color change is due to the water combining with the lanthanide-halide complex on the pores of the gel.

  17. Using Relative Humidity Forecasts to Manage Meningitis in the Sahel

    NASA Astrophysics Data System (ADS)

    Pandya, R. E.; Adams-Forgor, A.; Akweogno, P.; Awine, T.; Dalaba, M.; Dukic, V.; Dumont, A.; Hayden, M.; Hodgson, A.; Hopson, T. M.; Hugonnet, S.; Yoksas, T. C.

    2012-12-01

    the number cases of meningitis in the Sahel. Using currently available forecast models contributed through the WMO Thorpex-Tigge project, and applying quantile regression to enhance their accuracy, we can forecast the average weekly relative humidity to two weeks in advance which allows us to anticipate the end of an epidemic in a region of the Sahel up to four weeks in advance. This would allow public health officials to deploy vaccines to areas in which the epidemics are likely to persist due to continued dryness and avoid vaccinating in areas where the epidemics will end with higher humidity. Our presentation will conclude by introducing the relative humidity decision-information tool developed for use by public-health officials. We will also summarize the results of a weekly meningitis forecast exercise held during the 2011-2012 dry season with public health decision makers from several African countries and the World Health Organization. Finally, we highlight some results of concurrent socio-economic research that suggests other interventions for managing meningitis and helps quantify the economic impact of the disease in Ghana. Overall, while our research has demonstrated an actionable relationship between weather and disease, this relationship is only one factor in a complex and coupled human-natural system which merits continued investigation.

  18. Low-temperature oxidation of magnetite - a humidity sensitive process?

    NASA Astrophysics Data System (ADS)

    Appel, Erwin; Fang, Xiaomin; Herb, Christian; Hu, Shouyun

    2015-04-01

    carbonate erosion that reflects higher precipitation matches with stronger maghemitization. In the arid Qaidam region we interpret the humidity variation by regional water recycling related to glacial-interglacial periods. In the sub-tropical Heqing region humidity fluctuations may be caused by a changing relative influence of the Indian summer monsoon.

  19. Nanomechanical humidity detection through porous alumina cantilevers

    PubMed Central

    Klimenko, Alexey; Lebedev, Vasiliy; Lukashin, Alexey; Eliseev, Andrey

    2015-01-01

    Summary We present here the behavior of the resonance frequency of porous anodic alumina cantilever arrays during water vapor adsorption and emphasize their possible use in the micromechanical sensing of humidity levels at least in the range of 10–22%. The sensitivity of porous anodic aluminium oxide cantilevers (Δf/Δm) and the humidity sensitivity equal about 56 Hz/pg and about 100 Hz/%, respectively. The approach presented here for the design of anodic alumina cantilever arrays by the combination of anodic oxidation and photolithography enables easy control over porosity, surface area, geometric and mechanical characteristics of the cantilever arrays for micromechanical sensing. PMID:26199836

  20. Problem Periods

    MedlinePlus

    ... gov/ Home Body Getting your period Problem periods Problem periods It’s common to have cramps or feel ... doctor Some common period problems Signs of period problems top One way to know if you may ...

  1. Comparison of Single-Point and Continuous Sampling Methods for Estimating Residential Indoor Temperature and Humidity.

    PubMed

    Johnston, James D; Magnusson, Brianna M; Eggett, Dennis; Collingwood, Scott C; Bernhardt, Scott A

    2015-01-01

    Residential temperature and humidity are associated with multiple health effects. Studies commonly use single-point measures to estimate indoor temperature and humidity exposures, but there is little evidence to support this sampling strategy. This study evaluated the relationship between single-point and continuous monitoring of air temperature, apparent temperature, relative humidity, and absolute humidity over four exposure intervals (5-min, 30-min, 24-hr, and 12-days) in 9 northern Utah homes, from March-June 2012. Three homes were sampled twice, for a total of 12 observation periods. Continuous data-logged sampling was conducted in homes for 2-3 wks, and simultaneous single-point measures (n = 114) were collected using handheld thermo-hygrometers. Time-centered single-point measures were moderately correlated with short-term (30-min) data logger mean air temperature (r = 0.76, β = 0.74), apparent temperature (r = 0.79, β = 0.79), relative humidity (r = 0.70, β = 0.63), and absolute humidity (r = 0.80, β = 0.80). Data logger 12-day means were also moderately correlated with single-point air temperature (r = 0.64, β = 0.43) and apparent temperature (r = 0.64, β = 0.44), but were weakly correlated with single-point relative humidity (r = 0.53, β = 0.35) and absolute humidity (r = 0.52, β = 0.39). Of the single-point RH measures, 59 (51.8%) deviated more than ±5%, 21 (18.4%) deviated more than ±10%, and 6 (5.3%) deviated more than ±15% from data logger 12-day means. Where continuous indoor monitoring is not feasible, single-point sampling strategies should include multiple measures collected at prescribed time points based on local conditions. PMID:26030088

  2. Stalling Out: The Relative Progress of African Americans.

    ERIC Educational Resources Information Center

    Tidwell, Billy J.

    The socioeconomic progress of African Americans appears to be in a stalled state. This study analyzes the progress of African Americans toward parity with Whites over a 15- to 20-year period in the following areas: (1) employment; (2) economic development; (3) education; (4) health; (5) housing; and (6) political empowerment. For individual…

  3. Planation surfaces as a record of medium to large wavelength deformation: the example of the Lake Albert Rift (Uganda) on the East African Dome

    NASA Astrophysics Data System (ADS)

    Brendan, Simon; François, Guillocheau; Cécile, Robin; Jean, Braun; Olivier, Dauteuil; Massimo, Dall'Asta

    2016-04-01

    African relief is characterized by planation surfaces, some of them of continental scale. These surfaces are slightly deformed according to different wavelengths (x10 km; x100 km, x1000 km) which record both mantle dynamics (very long wavelength, x 1000 km) and lithosphere deformation (long wavelength deformation, x 100 km). Different types of these planation surfaces are recognized: - Etchplains capped by iron-duricrust which correspond to erosional nearly flat weathered surfaces resulting from the growth of laterites under warm and humid conditions. - Pediments which define mechanical erosional surfaces with concave or rectilinear profiles delimited by upslope scarps connected upstream with the upper landforms. We here focused on the Lake Albert Rift at the northern termination of the western branch of the East African Rift System of which the two branches are surimposed on the East-African Dome. Different wavelengths of deformation were characterized based on the 3D mapping of stepped planation surfaces: (1) very long wavelength deformations resulting from the uplift of the East African Dome; (2) long wavelength deformations resulting from the opening of the eastern branch and (3) medium wavelength deformations represented by the uplift of rift shoulders like the Rwenzori Mountains. The paleo-landscape reconstruction of Uganda shows the existence of four generations of landforms dated according to their geometrical relationships with volcanic rocks. A four stepped evolution of the Ugandan landforms is proposed: • 70 - 22 Ma: generation of two weathered planation surfaces (etchplain Uw and Iw). The upper one (Uw) records a very humid period culminating at time of the Early Eocene Climatic Optimum (70-45 Ma). It corresponds to the African Surface. A first uplift of the East African Dome generates a second lower planation surface (Iw) connected to the Atlantic Ocean base level; • 17-2.7 Ma: planation of large pediplains connected to the local base level induced

  4. Group 3: Humidity, Temperature and Voltage (Presentation)

    SciTech Connect

    Wohlgemuth, J.

    2013-09-01

    This is a summary of the work of Group 3 of the International PV QA Task Force. Group 3 is chartered to develop accelerated stress tests that can be used as comparative predictors of module lifetime versus stresses associated with humidity, temperature and voltage.

  5. The Temperature Humidity Infrared Radiometer (THIR) subsystem

    NASA Technical Reports Server (NTRS)

    Cherrix, G. T.

    1978-01-01

    The infrared radiation from the earth in two spectral bands during both day and night portions of the orbit is measured. Pictures of cloud cover, three dimensional mappings of cloud cover, temperature mappings of clouds, land, and ocean surface, cirrus cloud content, atmospheric contamination, and relative humidity are provided.

  6. Ambient humidity and the skin: the impact of air humidity in healthy and diseased states.

    PubMed

    Goad, N; Gawkrodger, D J

    2016-08-01

    Humidity, along with other climatic factors such as temperature and ultraviolet radiation, can have an important impact on the skin. Limited data suggest that external humidity influences the water content of the stratum corneum. An online literature search was conducted through Pub-Med using combinations of the following keywords: skin, skin disease, humidity, dermatoses, dermatitis, eczema, and mist. Publications included in this review were limited to (i) studies in humans or animals, (ii) publications showing relevance to the field of dermatology, (iii) studies published in English and (iv) publications discussing humidity as an independent influence on skin function. Studies examining environmental factors as composite influences on skin health are only included where the impact of humidity on the skin is also explored in isolation of other environmental factors. A formal systematic review was not feasible for this topic due to the heterogeneity of the available research. Epidemiological studies indicated an increase in eczema with low internal (indoors) humidity and an increase in eczema with external high humidity. Other studies suggest that symptoms of dry skin appear with low humidity internal air-conditioned environments. Murine studies determined that low humidity caused a number of changes in the skin, including the impairment of the desquamation process. Studies in humans demonstrated a reduction in transepidermal water loss (TEWL) (a measure of the integrity of the skin's barrier function) with low humidity, alterations in the water content in the stratum corneum, decreased skin elasticity and increased roughness. Intervention with a humidifying mist increased the water content of the stratum corneum. Conversely, there is some evidence that low humidity conditions can actually improve the barrier function of the skin. Ambient relative humidity has an impact on a range of parameters involved in skin health but the literature is inconclusive. Further

  7. Data Center Economizer Contamination and Humidity Study

    SciTech Connect

    Shehabi, Arman; Tschudi, William; Gadgil, Ashok

    2007-03-06

    Data centers require continuous air conditioning to address high internal heat loads (heat release from equipment) and maintain indoor temperatures within recommended operating levels for computers. Air economizer cycles, which bring in large amounts of outside air to cool internal loads when weather conditions are favorable, could save cooling energy. There is reluctance from many data center owners to use this common cooling technique, however, due to fear of introducing pollutants and potential loss of humidity control. Concerns about equipment failure from airborne pollutants lead to specifying as little outside air as permissible for human occupants. To investigate contamination levels, particle monitoring was conducted at 8 data centers in Northern California. Particle counters were placed at 3 to 4 different locations within and outside of each data center evaluated in this study. Humidity was also monitored at many of the sites to determine how economizers affect humidity control. Results from this study indicate that economizers do increase the outdoor concentration in data centers, but this concentration, when averaged annually, is still below current particle concentration limits. Study results are summarized below: (1) The average particle concentrations measured at each location, both outside and at the servers, are shown in Table 1. Measurements show low particle concentrations at all data centers without economizers, regardless of outdoor particle concentrations. Particle concentrations were typically an order of magnitude below both outside particle concentrations and recently published ASHRAE standards. (2) Economizer use caused sharp increases in particle concentrations when the economizer vents were open. The particle concentration in the data centers, however, quickly dropped back to pre-economizer levels when the vents closed. Since economizers only allow outside air part of the time, the annual average concentrations still met the ASHRAE

  8. Highly sensitive humidity sensing properties of carbon quantum dots films

    SciTech Connect

    Zhang, Xing; Ming, Hai; Liu, Ruihua; Han, Xiao; Kang, Zhenhui; Liu, Yang; Zhang, Yonglai

    2013-02-15

    Graphical abstract: Display Omitted Highlights: ► A humidity sensing device was fabricated based on carbon quantum dots (CQDs) films. ► The conductivity of the CQDs films shows a linear and rapid response to atmosphere humidity. ► The humidity sensing property was due to the hydrogen bonds between the functional groups on CQDs. -- Abstract: We reported the fabrication of a humidity sensing device based on carbon quantum dots (CQDs) film. The conductivity of the CQDs film has a linear and rapid response to relative humidity, providing the opportunity for the fabrication of humidity sensing devices. The mechanism of our humidity sensor was proposed to be the formation of hydrogen bonds between carbon quantum dots and water molecules in the humidity environment, which significantly promote the electrons migration. In a control experiment, this hypothesis was confirmed by comparing the humidity sensitivity of candle soot (i.e. carbon nanoparticles) with and without oxygen containing groups on the surfaces.

  9. Nuances of Error: Considerations Relevant to African American Vernacular English and Learning to Read

    ERIC Educational Resources Information Center

    Compton-Lilly, Catherine

    2005-01-01

    This paper explores the presence of African American Vernacular English patterns in the reading of one child over a 20-week period. In this paper, I present insights from linguists about African American Vernacular English, list linguistic patterns characteristic of African American Vernacular English speakers, examine the relationship between the…

  10. KZai 02 pollen record, an insight into West African monsoon fluctuations during the Last Climatic Cycle

    NASA Astrophysics Data System (ADS)

    Dalibard, M.; Popescu, S.; Maley, J.; Suc, J.

    2012-12-01

    Climate of the circum-Atlantic intertropical zone is driven by the ocean/atmosphere dynamics in response to variations of yearly insolation. These latitudes correspond to the convergence of the Hadley cells expressed on earth surface by intense trade winds and in lower troposphere by the African easterly jet making the edges of the intertropical zone relatively dry, while humidity is concentrated near the Equator. This phenomenon generates a precipitation front, known as the InterTropical Convergence Zone (ITCZ), the oscillations of which regulate the latitudinal vegetation distribution. Pollen record of core KZai 02 (Guinea Gulf) allows high resolution reconstruction of variations of past ecosystems over Central Africa during the Last Climatic Cycle. Plant taxa recorded in pollen analyses have been clustered according to their ecological requirements and African phytogeography. Fluctuations of these groups inform on precipitation intensity and their distribution during the last 130 ka. During Glacials, an open vegetation made of Cyperaceae marshes developed in the central Zaire/Congo Basin, surrounded by savannah on borders and afromontane forests on reliefs. Composition and distribution of vegetation indicate a decrease in monsoon activity and the strengthening of the precipitation front in the center of the basin. Interglacial phases are characterized by rain forest expansion over Central Africa in response to a precipitation enhancement associated with a northward shift of the rainfall front. Replacement of afromontane forest and marsh ecosystems by savannah then lowland pioneering, warm-temperate and rain forests characterized glacial/interglacial transitions. This succession suggests the increasing influence of at least two climatic parameters: the water availability and temperature and/or CO2 fluctuation. Spectral analysis applied to vegetation groups evidences the forcing of insolation, mainly driven by precession, on the West African monsoon system. Sub

  11. Evaluation of Humidity Control Options in Hot-Humid Climate Homes (Fact Sheet)

    SciTech Connect

    Not Available

    2011-12-01

    This technical highlight describes NREL research to analyze the indoor relative humidity in three home types in the hot-humid climate zone, and examine the impacts of various dehumidification equipment and controls. As the Building America program researches construction of homes that achieve greater source energy savings over typical mid-1990s construction, proper modeling of whole-house latent loads and operation of humidity control equipment has become a high priority. Long-term high relative humidity can cause health and durability problems in homes, particularly in a hot-humid climate. In this study, researchers at the National Renewable Energy Laboratory (NREL) used the latest EnergyPlus tool equipped with the moisture capacitance model to analyze the indoor relative humidity in three home types: a Building America high-performance home; a mid-1990s reference home; and a 2006 International Energy Conservation Code (IECC)-compliant home in hot-humid climate zones. They examined the impacts of various dehumidification equipment and controls on the high-performance home where the dehumidification equipment energy use can become a much larger portion of whole-house energy consumption. The research included a number of simulated cases: thermostat reset, A/C with energy recovery ventilator, heat exchanger assisted A/C, A/C with condenser reheat, A/C with desiccant wheel dehumidifier, A/C with DX dehumidifier, A/C with energy recovery ventilator, and DX dehumidifier. Space relative humidity, thermal comfort, and whole-house source energy consumption were compared for indoor relative humidity set points of 50%, 55%, and 60%. The study revealed why similar trends of high humidity were observed in all three homes regardless of energy efficiency, and why humidity problems are not necessarily unique in the high-performance home. Thermal comfort analysis indicated that occupants are unlikely to notice indoor humidity problems. The study confirmed that supplemental

  12. Latitudinal Hydrologic Variability Along the East African Rift, Over the Past 200 Kyr

    NASA Astrophysics Data System (ADS)

    Scholz, C. A.

    2014-12-01

    Within the deep sediments of the large lakes of Africa's Great Rift Valley are continuous environmental records of remarkable antiquity and fidelity. Not only do stratigraphic sections from these basins extend back millions of years, many of the intervals represented contain high-resolution material of decadal resolution or better. East African lake basins remain sparsely sampled however, with only a few long and continuous records available. Our ability to image the lakes using seismic reflection methods greatly exceeds our opportunities for coring and drilling however; assessing stratal relationships observed in the geophysical data permits powerful inferences about past hydrologic changes. With intensive hydrocarbon exploration work underway in East Africa, industry well data can also help constrain and ground truth basin histories. Substantial spatio-temporal hydrologic variability is observed in East African basins over the past 200 kyr. Paleohydrological changes in the late Pleistocene and early Holocene are now well constrained in the northern hemisphere East African topics, with widespread aridity and in some cases lake desiccation observed during Heinrich Event 1. A climate recovery followed in the northern hemisphere East African tropics, with the early Holocene African Humid Period a time of positive water balance across most of the rift valley. The paleohydrology of southern hemisphere tropical East Africa is more equivocal, for instance with negligible draw-down of Lake Malawi at HE1. Whereas these late Pleistocene events represent substantial climate reorganizations, severe droughts during the middle-late Pleistocene (150-65 kyr BP) were far more intense, and produced much more severe drawdowns of Lakes Malawi and Tanganyika. Scientific drill cores, kullenberg cores, and extensive seismic reflection data sets from Lakes Malawi and Tanganyika provide indisputable evidence for lowstands of -500m and -600 m respectively. Climate changes that lowered the

  13. African and non-African admixture components in African Americans and an African Caribbean population.

    PubMed

    Murray, Tanda; Beaty, Terri H; Mathias, Rasika A; Rafaels, Nicholas; Grant, Audrey Virginia; Faruque, Mezbah U; Watson, Harold R; Ruczinski, Ingo; Dunston, Georgia M; Barnes, Kathleen C

    2010-09-01

    Admixture is a potential source of confounding in genetic association studies, so it becomes important to detect and estimate admixture in a sample of unrelated individuals. Populations of African descent in the US and the Caribbean share similar historical backgrounds but the distributions of African admixture may differ. We selected 416 ancestry informative markers (AIMs) to estimate and compare admixture proportions using STRUCTURE in 906 unrelated African Americans (AAs) and 294 Barbadians (ACs) from a study of asthma. This analysis showed AAs on average were 72.5% African, 19.6% European and 8% Asian, while ACs were 77.4% African, 15.9% European, and 6.7% Asian which were significantly different. A principal components analysis based on these AIMs yielded one primary eigenvector that explained 54.04% of the variation and captured a gradient from West African to European admixture. This principal component was highly correlated with African vs. European ancestry as estimated by STRUCTURE (r(2)=0.992, r(2)=0.912, respectively). To investigate other African contributions to African American and Barbadian admixture, we performed PCA on approximately 14,000 (14k) genome-wide SNPs in AAs, ACs, Yorubans, Luhya and Maasai African groups, and estimated genetic distances (F(ST)). We found AAs and ACs were closest genetically (F(ST)=0.008), and both were closer to the Yorubans than the other East African populations. In our sample of individuals of African descent, approximately 400 well-defined AIMs were just as good for detecting substructure as approximately 14,000 random SNPs drawn from a genome-wide panel of markers. PMID:20717976

  14. The African superswell

    NASA Technical Reports Server (NTRS)

    Nyblade, Andrew A.; Robinson, Scott W.

    1994-01-01

    Maps of residual bathymetry in the ocean basins around the African continent reveal a broad bathymetric swell in the southeastern Atlantic Ocean with an amplitude of about 500 m. We propose that this region of anomalously shallow bathymetry, together with the contiguous eastern and southern African plateaus, form a superswell which we refer to as the African superswell. The origin of the African superswell is uncertain. However, rifting and volcanism in eastern Africa, as well as heat flow measurements in southern Africa and the southeastern Atlantic Ocean, suggest that the superswell may be attributed, at least in part, to heating of the lithosphere.

  15. Formaldehyde emissions from ventilation filters under different relative humidity conditions.

    PubMed

    Sidheswaran, Meera; Chen, Wenhao; Chang, Agatha; Miller, Robert; Cohn, Sebastian; Sullivan, Douglas; Fisk, William J; Kumagai, Kazukiyo; Destaillats, Hugo

    2013-05-21

    Formaldehyde emissions from fiberglass and polyester filters used in building heating, ventilation, and air conditioning (HVAC) systems were measured in bench-scale tests using 10 and 17 cm(2) coupons over 24 to 720 h periods. Experiments were performed at room temperature and four different relative humidity settings (20, 50, 65, and 80% RH). Two different air flow velocities across the filters were explored: 0.013 and 0.5 m/s. Fiberglass filters emitted between 20 and 1000 times more formaldehyde than polyester filters under similar RH and airflow conditions. Emissions increased markedly with increasing humidity, up to 10 mg/h-m(2) at 80% RH. Formaldehyde emissions from fiberglass filters coated with tackifiers (impaction oils) were lower than those from uncoated fiberglass media, suggesting that hydrolysis of other polymeric constituents of the filter matrix, such as adhesives or binders was likely the main formaldehyde source. These laboratory results were further validated by performing a small field study in an unoccupied office. At 80% RH, indoor formaldehyde concentrations increased by 48-64%, from 9-12 μg/m(3) to 12-20 μg/m(3), when synthetic filters were replaced with fiberglass filtration media in the HVAC units. Better understanding of the reaction mechanisms and assessing their overall contributions to indoor formaldehyde levels will allow for efficient control of this pollution source. PMID:23597095

  16. Biphilic Surfaces for Enhanced Water Collection from Humid Air

    NASA Astrophysics Data System (ADS)

    Benkoski, Jason; Gerasopoulos, Konstantinos; Luedeman, William

    Surface wettability plays an important role in water recovery, distillation, dehumidification, and heat transfer. The efficiency of each process depends on the rate of droplet nucleation, droplet growth, and mass transfer. Unfortunately, hydrophilic surfaces are good at nucleation but poor at shedding. Hydrophobic surfaces are the reverse. Many plants and animals overcome this tradeoff through biphilic surfaces with patterned wettability. For example, the Stenocara beetle uses hydrophilic patches on a superhydrophobic background to collect fog from air. Cribellate spiders similarly collect fog on their webs through periodic spindle-knot structures. In this study, we investigate the effects of wettability patterns on the rate of water collection from humid air. The steady state rate of water collection per unit area is measured as a function of undercooling, angle of inclination, water contact angle, hydrophilic patch size, patch spacing, area fraction, and patch height relative to the hydrophobic background. We then model each pattern by comparing the potential and kinetic energy of a droplet as it rolls downwards at a fixed angle. The results indicate that the design rules for collecting fog differ from those for condensation from humid air. The authors gratefully acknowledge the Office of Naval Research for financial support through Grant Number N00014-15-1-2107.

  17. Effect of Relative Humidity on Formaldehyde Decontamination

    PubMed Central

    Spiner, David R.; Hoffman, Robert K.

    1971-01-01

    Death rate studies were conducted to determine the effect of varying the concentration, humidity, and type of surface on the sporicidal activity of formaldehyde gas. Washed and unwashed spores were similarly exposed to detect the influence of residual nutrient growth medium upon the rate of kill. The results indicated that the sporicidal activity of formaldehyde gas varies directly with its concentration. Relative humidities (RH) over 50% proved essential for sterility. Spores on a porous surface (cotton cloth) were more readily killed at lower RH than those on a nonporous surface (glass). The reverse occurred at very high RH. At 75% RH, the unwashed spores on glass were killed faster than the washed spores. Images PMID:5002898

  18. Wireless sensor for temperature and humidity measurement

    NASA Astrophysics Data System (ADS)

    Drumea, Andrei; Svasta, Paul

    2010-11-01

    Temperature and humidity sensors have a broad range of applications, from heating and ventilation of houses to controlled drying of fruits, vegetables or meat in food industry. Modern sensors are integrated devices, usually MEMS, factory-calibrated and with digital output of measured parameters. They can have power down modes for reduced energy consumption. Such an integrated device allows the implementation of a battery powered wireless sensor when coupled with a low power microcontroller and a radio subsystem. A radio sensor can work independently or together with others in a radio network. Presented paper focuses mainly on measurement and construction aspects of sensors for temperature and humidity designed and implemented by authors; network aspects (communication between two or more sensors) are not analyzed.

  19. Residential Dehumidification Systems Research for Hot-Humid Climates

    SciTech Connect

    2005-02-01

    Twenty homes were tested and monitored in the hot-humid climate of Houston, Texas, to evaluate the humidity control performance and operating cost of six integrated dehumidification and ventilation systems.

  20. Potato growth in response to relative humidity

    NASA Technical Reports Server (NTRS)

    Wheeler, R. M.; Tibbitts, T. W.; Fitzpatrick, A. H.

    1989-01-01

    Potato plants (Solanum tuberosum L. cvs. Russet Burbank, Norland, and Denali) were grown for 56 days in controlled-environment rooms under continuous light at 20C and 50% or 85% RH. No significant differences in total plant dry weight were measured between the humidity treatments, but plants grown under 85% RH produced higher tuber yields. Leaf areas were greater under 50% RH and leaves tended to be larger and darker green than at 85% RH.

  1. Humidity local measurements in the middle atmosphere

    NASA Astrophysics Data System (ADS)

    Ovarlez, J.; Capus, J.; Forichon, M.; Ovarlez, H.

    1989-06-01

    The development of a hydrometer, to be applied in stratospheric balloons for humidity measurements, is described. The device is also designed for satellite data validation. Data from the experiment carried out in the Southern Hemisphere, in November and December 1988, is discussed. The measurements between 20 and 70 hPa showed a volume mixture ratio from 3 to 6. The mechanism of the equatorial stratosphere drying is considered.

  2. Color control in reflection holograms by humidity.

    PubMed

    Wuest, D R; Lakes, R S

    1991-06-10

    A method is presented which permits control of the reconstruction wavelength of reflection holograms and holographic optical elements. This approach makes use of developer and bleach which minimize emulsion shrinkage combined with control of ambient humidity to control the emulsion shrinkage during formation and reconstruction. A simple index matching approach to the elimination of the wood grain effect in reflection holograms is also presented. PMID:20700214

  3. Hydrophilic membrane-based humidity control.

    PubMed

    Scovazzo, P; Burgos, J; Hoehn, A; Todd, P

    1998-10-14

    A dehumidification system for low gravity plant growth experiments requires the generation of no free-liquid condensate and the recovery of water for reuse. In the systems discussed in this paper, the membrane is a barrier between the humid air phase and a liquid-coolant water phase. The coolant water temperature combined with a transmembrane pressure differential establishes a water flux from the humid air into the coolant water. Building on the work of others, we directly compared different hydrophilic membranes for humidity control. In a direct comparison of the hydrophilic membranes, hollow fiber cellulose ester membranes were superior to metal and ceramic membranes in the categories of condensation flux per surface area, ease of start-up, and stability. However, cellulose ester membranes were inferior to metal membranes in one significant category, durability. Dehumidification systems using mixed cellulose ester membranes failed after operational times of only hours to days. We propose that the ratio of fluid surface area to membrane material area (approximately = membrane porosity) controls the relative performances among membranes. In addition, we clarified design equations for operational parameters such as the transmembrane pressure differential. This technology has several potential benefits related to earth environmental issues including the minimization of airborne pathogen release and higher energy efficiency in air conditioning equipment. Utilizing these study results, we designed, constructed, and flew on the space shuttle missions a membrane-based dehumidification system for a plant growth chamber. PMID:11543067

  4. Tropical atmospheric circulations with humidity effects

    PubMed Central

    Hsia, Chun-Hsiung; Lin, Chang-Shou; Ma, Tian; Wang, Shouhong

    2015-01-01

    The main objective of this article is to study the effect of the moisture on the planetary scale atmospheric circulation over the tropics. The modelling we adopt is the Boussinesq equations coupled with a diffusive equation of humidity, and the humidity-dependent heat source is modelled by a linear approximation of the humidity. The rigorous mathematical analysis is carried out using the dynamic transition theory. In particular, we obtain mixed transitions, also known as random transitions, as described in Ma & Wang (2010 Discrete Contin. Dyn. Syst. 26, 1399–1417. (doi:10.3934/dcds.2010.26.1399); 2011 Adv. Atmos. Sci. 28, 612–622. (doi:10.1007/s00376-010-9089-0)). The analysis also indicates the need to include turbulent friction terms in the model to obtain correct convection scales for the large-scale tropical atmospheric circulations, leading in particular to the right critical temperature gradient and the length scale for the Walker circulation. In short, the analysis shows that the effect of moisture lowers the magnitude of the critical thermal Rayleigh number and does not change the essential characteristics of dynamical behaviour of the system. PMID:25568615

  5. East African climate pulses and early human evolution

    NASA Astrophysics Data System (ADS)

    Maslin, Mark A.; Brierley, Chris M.; Milner, Alice M.; Shultz, Susanne; Trauth, Martin H.; Wilson, Katy E.

    2014-10-01

    Current evidence suggests that all of the major events in hominin evolution have occurred in East Africa. Over the last two decades, there has been intensive work undertaken to understand African palaeoclimate and tectonics in order to put together a coherent picture of how the environment of East Africa has varied in the past. The landscape of East Africa has altered dramatically over the last 10 million years. It has changed from a relatively flat, homogenous region covered with mixed tropical forest, to a varied and heterogeneous environment, with mountains over 4 km high and vegetation ranging from desert to cloud forest. The progressive rifting of East Africa has also generated numerous lake basins, which are highly sensitive to changes in the local precipitation-evaporation regime. There is now evidence that the presence of precession-driven, ephemeral deep-water lakes in East Africa were concurrent with major events in hominin evolution. It seems the unusual geology and climate of East Africa created periods of highly variable local climate, which, it has been suggested could have driven hominin speciation, encephalisation and dispersal out of Africa. One example is the significant hominin speciation and brain expansion event at ˜1.8 Ma that seems to have been coeval with the occurrence of highly variable, extensive, deep-water lakes. This complex, climatically very variable setting inspired first the variability selection hypothesis, which was then the basis for the pulsed climate variability hypothesis. The newer of the two suggests that the long-term drying trend in East Africa was punctuated by episodes of short, alternating periods of extreme humidity and aridity. Both hypotheses, together with other key theories of climate-evolution linkages, are discussed in this paper. Though useful the actual evolution mechanisms, which led to early hominins are still unclear and continue to be debated. However, it is clear that an understanding of East African

  6. Orbital- versus glacial-mode forcing of tropical African climate: Results of scientific drilling in Lake Malawi, East Africa

    NASA Astrophysics Data System (ADS)

    Scholz, C. A.; Cohen, A. S.; Johnson, T. C.; King, J. W.; Brown, E. T.; Lyons, R. P.; Stone, J. R.; Beuning, K. R.

    2007-12-01

    Lake Malawi extends from 9-14 degrees S within the East African Rift Valley, and at 700 m deep, contains more than 20 percent of the surface water on the African continent. In 2005 the Lake Malawi Scientific Drilling Project drilled 7 holes at two sites in the lake, recovering a continuous sediment record that samples much of the Quaternary. Detailed studies completed to date on sediments deposited during the past 145 ka indicate periods of severe aridity at precessional frequency between 135 and 75 ka, when the lake's water volume was periodically reduced by at least 95 percent. These dramatic drops in lake level (more than 550 m), signifying markedly arid conditions in the catchment, are documented in sediment lithology (decreased organic carbon content and increased authigenic carbonate content during severe lowstands), aquatic microfossils (appearance of a littoral ostracode fauna, and saline/alkaline lake diatom flora during extreme low lake stages), as well as in dramatic reductions in catchment pollen production. These intervals of pronounced tropical African aridity in the early late-Pleistocene were much more severe than the Last Glacial Maximum, and are consistent with sediment records from Lakes Tanganyika (East Africa) and Bosumtwi (West Africa). In all three lakes a major rise in water levels and a shift to more humid conditions is observed after ~70 ka. The transition to wetter, more stable conditions coincides with the relaxation of orbital eccentricity and a reduction in the amplitude of precession. The observed climate mode switch to decreased environmental variability is consistent with terrestrial and marine records from in and around tropical Africa, but these new drill cores provide evidence for dramatically drier conditions prior to 70 ka that have not as yet been detected in marine sediment records. Such climate change may have stimulated the expansion and migrations of early modern human populations.

  7. 7 CFR 28.301 - Measurement: humidity; temperature.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Measurement: humidity; temperature. 28.301 Section 28... for Length of Staple § 28.301 Measurement: humidity; temperature. The length of staple of any cotton... its fibers under a relative humidity of the atmosphere of 65 percent and a temperature of 70° F....

  8. 7 CFR 28.301 - Measurement: humidity; temperature.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Measurement: humidity; temperature. 28.301 Section 28... for Length of Staple § 28.301 Measurement: humidity; temperature. The length of staple of any cotton... its fibers under a relative humidity of the atmosphere of 65 percent and a temperature of 70 °F....

  9. 7 CFR 28.301 - Measurement: humidity; temperature.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Measurement: humidity; temperature. 28.301 Section 28... for Length of Staple § 28.301 Measurement: humidity; temperature. The length of staple of any cotton... its fibers under a relative humidity of the atmosphere of 65 percent and a temperature of 70 °F....

  10. 7 CFR 28.301 - Measurement: humidity; temperature.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Measurement: humidity; temperature. 28.301 Section 28... for Length of Staple § 28.301 Measurement: humidity; temperature. The length of staple of any cotton... its fibers under a relative humidity of the atmosphere of 65 percent and a temperature of 70 °F....

  11. 7 CFR 28.301 - Measurement: humidity; temperature.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Measurement: humidity; temperature. 28.301 Section 28... for Length of Staple § 28.301 Measurement: humidity; temperature. The length of staple of any cotton... its fibers under a relative humidity of the atmosphere of 65 percent and a temperature of 70 °F....

  12. 40 CFR 90.310 - Engine intake air humidity measurement.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 21 2012-07-01 2012-07-01 false Engine intake air humidity measurement... Emission Test Equipment Provisions § 90.310 Engine intake air humidity measurement. This section refers to... for the engine intake air, the ambient test cell humidity measurement may be used. (a)...

  13. 40 CFR 90.310 - Engine intake air humidity measurement.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Engine intake air humidity measurement... Emission Test Equipment Provisions § 90.310 Engine intake air humidity measurement. This section refers to... for the engine intake air, the ambient test cell humidity measurement may be used. (a)...

  14. 40 CFR 90.310 - Engine intake air humidity measurement.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 20 2014-07-01 2013-07-01 true Engine intake air humidity measurement... Emission Test Equipment Provisions § 90.310 Engine intake air humidity measurement. This section refers to... for the engine intake air, the ambient test cell humidity measurement may be used. (a)...

  15. 40 CFR 90.310 - Engine intake air humidity measurement.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 21 2013-07-01 2013-07-01 false Engine intake air humidity measurement... Emission Test Equipment Provisions § 90.310 Engine intake air humidity measurement. This section refers to... for the engine intake air, the ambient test cell humidity measurement may be used. (a)...

  16. 40 CFR 90.310 - Engine intake air humidity measurement.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 20 2011-07-01 2011-07-01 false Engine intake air humidity measurement... Emission Test Equipment Provisions § 90.310 Engine intake air humidity measurement. This section refers to... for the engine intake air, the ambient test cell humidity measurement may be used. (a)...

  17. Elimination of Coffee-Ring Formation by Humidity Cycling: A Numerical Study.

    PubMed

    Eales, Adam D; Routh, Alexander F

    2016-01-19

    Periodically switching between evaporation and condensation, or "humidity cycling", has potential for controlling the film shape that results from volatile droplets containing a nonvolatile material. It does not require adaptation of material properties nor the introduction of an external field to achieve a change in film shape. It was shown experimentally by Doi and coworkers [Kajiya et al. Langmuir 2010, 26, pp 10429-10432] that ring-shaped deposits can be removed through careful selection of the atmospheric conditions. We present a model, based on lubrication theory, that can predict the final film shape resulting from the humidity cycling process. We confirm that the refluidization of gelled regions during condensation and the subsequent inward flow is the mechanism responsible for the improved profiles. Furthermore, we find that an increase in the time spent condensing to that spent evaporating results in flatter films and that an optimal humidity cycling frequency exists. PMID:26694638

  18. 16 Extraordinary African Americans.

    ERIC Educational Resources Information Center

    Lobb, Nancy

    This collection for children tells the stories of 16 African Americans who helped make America what it is today. African Americans can take pride in the heritage of these contributors to society. Biographies are given for the following: (1) Sojourner Truth, preacher and abolitionist; (2) Frederick Douglass, abolitionist; (3) Harriet Tubman, leader…

  19. African Studies Computer Resources.

    ERIC Educational Resources Information Center

    Kuntz, Patricia S.

    African studies computer resources that are readily available in the United States with linkages to Africa are described, highlighting those most directly corresponding to African content. Africanists can use the following four fundamental computer systems: (1) Internet/Bitnet; (2) Fidonet; (3) Usenet; and (4) dial-up bulletin board services. The…

  20. African Literature as Celebration.

    ERIC Educational Resources Information Center

    Achebe, Chinua

    1989-01-01

    Describes the Igbo tradition of "Mbari," a communal creative enterprise that celebrates the world and the life lived in it through art. Contrasts the cooperative, social dimension of pre-colonial African culture with the exclusion and denial of European colonialism, and sees new African literature again celebrating human presence and dignity. (AF)

  1. Educating African American Males

    ERIC Educational Resources Information Center

    Bell, Edward E.

    2010-01-01

    Background: Schools across America spend money, invest in programs, and sponsor workshops, offer teacher incentives, raise accountability standards, and even evoke the name of Obama in efforts to raise the academic achievement of African American males. Incarceration and college retention rates point to a dismal plight for many African American…

  2. Africans Away from Home.

    ERIC Educational Resources Information Center

    Clarke, John Henrik

    Africans who were brought across the Atlantic as slaves never fully adjusted to slavery or accepted its inevitability. Resistance began on board the slave ships, where many jumped overboard or committed suicide. African slaves in South America led the first revolts against tyranny in the New World. The first slave revolt in the Caribbean occurred…

  3. Keeping African Masks Real

    ERIC Educational Resources Information Center

    Waddington, Susan

    2012-01-01

    Art is a good place to learn about our multicultural planet, and African masks are prized throughout the world as powerfully expressive artistic images. Unfortunately, multicultural education, especially for young children, can perpetuate stereotypes. Masks taken out of context lose their meaning and the term "African masks" suggests that there is…

  4. Diabetes in African Americans

    PubMed Central

    Marshall, M

    2005-01-01

    African Americans have a high risk for type 2 diabetes. Genetic traits, the prevalence of obesity, and insulin resistance all contribute to the risk of diabetes in the African American community. African Americans have a high rate of diabetic complications, because of poor glycaemic control and racial disparities in health care in the USA. African Americans with diabetes may have an atypical presentation that simulates type 1 diabetes, but then their subsequent clinical course is typical of type 2 diabetes. Culturally sensitive strategies, structured disease management protocols, and the assistance of nurses, diabetic educators, and other health care professionals are effective in improving the outcome of diabetes in the African American community. PMID:16344294

  5. Dynamics of Green Sahara Periods and Their Role in Hominin Evolution

    PubMed Central

    Larrasoaña, Juan C.; Roberts, Andrew P.; Rohling, Eelco J.

    2013-01-01

    Astronomically forced insolation changes have driven monsoon dynamics and recurrent humid episodes in North Africa, resulting in green Sahara Periods (GSPs) with savannah expansion throughout most of the desert. Despite their potential for expanding the area of prime hominin habitats and favouring out-of-Africa dispersals, GSPs have not been incorporated into the narrative of hominin evolution due to poor knowledge of their timing, dynamics and landscape composition at evolutionary timescales. We present a compilation of continental and marine paleoenvironmental records from within and around North Africa, which enables identification of over 230 GSPs within the last 8 million years. By combining the main climatological determinants of woody cover in tropical Africa with paleoenvironmental and paleoclimatic data for representative (Holocene and Eemian) GSPs, we estimate precipitation regimes and habitat distributions during GSPs. Their chronology is consistent with the ages of Saharan archeological and fossil hominin sites. Each GSP took 2–3 kyr to develop, peaked over 4–8 kyr, biogeographically connected the African tropics to African and Eurasian mid latitudes, and ended within 2–3 kyr, which resulted in rapid habitat fragmentation. We argue that the well-dated succession of GSPs presented here may have played an important role in migration and evolution of hominins. PMID:24146882

  6. Dynamics of green Sahara periods and their role in hominin evolution.

    PubMed

    Larrasoaña, Juan C; Roberts, Andrew P; Rohling, Eelco J

    2013-01-01

    Astronomically forced insolation changes have driven monsoon dynamics and recurrent humid episodes in North Africa, resulting in green Sahara Periods (GSPs) with savannah expansion throughout most of the desert. Despite their potential for expanding the area of prime hominin habitats and favouring out-of-Africa dispersals, GSPs have not been incorporated into the narrative of hominin evolution due to poor knowledge of their timing, dynamics and landscape composition at evolutionary timescales. We present a compilation of continental and marine paleoenvironmental records from within and around North Africa, which enables identification of over 230 GSPs within the last 8 million years. By combining the main climatological determinants of woody cover in tropical Africa with paleoenvironmental and paleoclimatic data for representative (Holocene and Eemian) GSPs, we estimate precipitation regimes and habitat distributions during GSPs. Their chronology is consistent with the ages of Saharan archeological and fossil hominin sites. Each GSP took 2-3 kyr to develop, peaked over 4-8 kyr, biogeographically connected the African tropics to African and Eurasian mid latitudes, and ended within 2-3 kyr, which resulted in rapid habitat fragmentation. We argue that the well-dated succession of GSPs presented here may have played an important role in migration and evolution of hominins. PMID:24146882

  7. Effect of humidity on infection of turkeys with Alcaligenes faecalis.

    PubMed

    Slavik, M F; Skeeles, J K; Beasley, J N; Harris, G C; Roblee, P; Hellwig, D

    1981-01-01

    Turkeys maintained at 75% to 80% relative humidity were more adversely affected by Alcaligenes faecalis infection than turkeys maintained at 20 to 35% relative humidity. Alcaligenes faecalis was reisolated earlier and more often from turkeys maintained at the higher humidity. Clinically, the turkeys maintained at high humidity exhibited both sinusitis and conjunctivitis earlier than the turkeys at low humidity. In both groups, antibody titers as determined by a microagglutination test developed by 2 weeks postinoculation and started to decline after the third week, lymphocytosis was demonstrated at 1 week postinoculation, and a lymphopenia developed at 5 weeks postinoculation. PMID:7337613

  8. Long-distance recording of the humidity over the sea

    NASA Technical Reports Server (NTRS)

    Buklanov, V. V.; Klaptsov, V. M.

    1975-01-01

    A procedure is developed for long distance recording of humidity over the sea that uses humidity detectors of the sorption type, whose electrical properties depend on the relative humidity of the air. The moisture sensitive material of the hygristor is the organic polymer polyacrylonitryl, deposited on silver electrodes and thermally treated. In the measurements of the relative humidity from 60% to 95%, the resistance of the hygristor varies from several hundred kiloohms to a few kiloohms, and is an essentially nonlinear function of the humidity.

  9. African bees to control African elephants

    NASA Astrophysics Data System (ADS)

    Vollrath, Fritz; Douglas-Hamilton, Iain

    2002-11-01

    Numbers of elephants have declined in Africa and Asia over the past 30 years while numbers of humans have increased, both substantially. Friction between these two keystone species is reaching levels which are worryingly high from an ecological as well as a political viewpoint. Ways and means must be found to keep the two apart, at least in areas sensitive to each species' survival. The aggressive African bee might be one such method. Here we demonstrate that African bees deter elephants from damaging the vegetation and trees which house their hives. We argue that bees can be employed profitably to protect not only selected trees, but also selected areas, from elephant damage.

  10. Positive impedance humidity sensors via single-component materials

    PubMed Central

    Qian, Jingwen; Peng, Zhijian; Shen, Zhenguang; Zhao, Zengying; Zhang, Guoliang; Fu, Xiuli

    2016-01-01

    Resistivity-type humidity sensors have been investigated with great interest due to the increasing demands in industry, agriculture and daily life. To date, most of the available humidity sensors have been fabricated based on negative humidity impedance, in which the electrical resistance decreases as the humidity increases, and only several carbon composites have been reported to present positive humidity impedance. However, here we fabricate positive impedance humidity sensors only via single-component WO3−x crystals. The resistance of WO3−x crystal sensors in response to relative humidity could be tuned from a negative to positive one by increasing the compositional x. And it was revealed that the positive humidity impedance was driven by the defects of oxygen vacancy. This result will extend the application field of humidity sensors, because the positive humidity impedance sensors would be more energy-efficient, easier to be miniaturized and electrically safer than their negative counterparts for their lower operation voltages. And we believe that constructing vacancies in semiconducting materials is a universal way to fabricate positive impedance humidity sensors. PMID:27150936

  11. Positive impedance humidity sensors via single-component materials.

    PubMed

    Qian, Jingwen; Peng, Zhijian; Shen, Zhenguang; Zhao, Zengying; Zhang, Guoliang; Fu, Xiuli

    2016-01-01

    Resistivity-type humidity sensors have been investigated with great interest due to the increasing demands in industry, agriculture and daily life. To date, most of the available humidity sensors have been fabricated based on negative humidity impedance, in which the electrical resistance decreases as the humidity increases, and only several carbon composites have been reported to present positive humidity impedance. However, here we fabricate positive impedance humidity sensors only via single-component WO3-x crystals. The resistance of WO3-x crystal sensors in response to relative humidity could be tuned from a negative to positive one by increasing the compositional x. And it was revealed that the positive humidity impedance was driven by the defects of oxygen vacancy. This result will extend the application field of humidity sensors, because the positive humidity impedance sensors would be more energy-efficient, easier to be miniaturized and electrically safer than their negative counterparts for their lower operation voltages. And we believe that constructing vacancies in semiconducting materials is a universal way to fabricate positive impedance humidity sensors. PMID:27150936

  12. Positive impedance humidity sensors via single-component materials

    NASA Astrophysics Data System (ADS)

    Qian, Jingwen; Peng, Zhijian; Shen, Zhenguang; Zhao, Zengying; Zhang, Guoliang; Fu, Xiuli

    2016-05-01

    Resistivity-type humidity sensors have been investigated with great interest due to the increasing demands in industry, agriculture and daily life. To date, most of the available humidity sensors have been fabricated based on negative humidity impedance, in which the electrical resistance decreases as the humidity increases, and only several carbon composites have been reported to present positive humidity impedance. However, here we fabricate positive impedance humidity sensors only via single-component WO3‑x crystals. The resistance of WO3‑x crystal sensors in response to relative humidity could be tuned from a negative to positive one by increasing the compositional x. And it was revealed that the positive humidity impedance was driven by the defects of oxygen vacancy. This result will extend the application field of humidity sensors, because the positive humidity impedance sensors would be more energy-efficient, easier to be miniaturized and electrically safer than their negative counterparts for their lower operation voltages. And we believe that constructing vacancies in semiconducting materials is a universal way to fabricate positive impedance humidity sensors.

  13. Littoral sedimentation of rift lakes: an illustrated overview from the modern to Pliocene Lake Turkana (East African Rift System, Kenya)

    NASA Astrophysics Data System (ADS)

    Schuster, Mathieu; Nutz, Alexis

    2015-04-01

    Existing depositional models for rift lakes can be summarized as clastics transported by axial and lateral rivers, then distributed by fan-deltas and/or deltas into a standing water body which is dominated by settling of fine particles, and experiencing occasional coarser underflows. Even if known from paleolakes and modern lakes, reworking of clastics by alongshore drift, waves and storms are rarely considered in depositional models. However, if we consider the lake Turkana Basin (East African Rift System, Kenya) it is obvious that this vision is incomplete. Three representative time slices are considered here: the modern Lake Turkana, the Megalake Turkana which developed thanks to the African Humid Period (Holocene), and the Plio-Pleistocene highstand episodes of paleolake Turkana (Nachukui, Shungura and Koobi Fora Formations, Omo Group). First, remarkable clastic morphosedimentary structures such as beach ridges, spits, washover fans, lagoons, or wave-dominated deltas are very well developed along the shoreline of modern lake Turkana, suggesting strong hydrodynamics responsible for a major reworking of the fluvial-derived clastics all along the littoral zone (longshore and cross-shore transport) of the lake. Similarly, past hydrodynamics are recorded from prominent raised beach ridges and spits, well-preserved all around the lake, above its present water-level (~360 m asl) and up to ~455 m. These large-scale clastic morphosedimentary structures also record the maximum extent of Megalake Turkana during the African Humid Period, as well as its subsequent regression forced by the end of the Holocene climatic optimum. Several hundreds of meters of fluvial-deltaic-lacustrine deposits spanning the Pliocene-Pleistocene are exposed in the Turkana basin thanks to tectonic faulting. These deposits are world famous for their paleontological and archeological content that documents the very early story of Mankind. They also preserve several paleolake highstand episodes with

  14. Extension of Humidity Standards to Frost Point

    NASA Astrophysics Data System (ADS)

    Choi, B. I.; Lee, S.-W.; Kim, J. C.; Woo, S. B.

    2015-08-01

    The KRISS low frost-point humidity generator which has been operated by the two-temperature method in the frost-point range from to since 2006 is reformed to a two-temperature, two-pressure type, in order to extend the calibration capability to a frost point of . The temperature and pressure of the saturator were controlled to and 1 MPa, respectively. The water-vapor mole ratio generated by the upgraded humidity generator reached . The uncertainty of the generator was estimated by calculations as well as a series of experiments including the stability of the generated frost point, the saturation efficiency with a varied gas flow rate, and the change of water-vapor mole ratio in the tubing line. The standard uncertainty of the generator is less than at the frost point of and is increased to at the frost point of . The increase in uncertainty is mainly due to the water adsorption/desorption on the internal surface of tubing from the saturator to the hygrometer.

  15. Entropy and Mixing : Titan's Humidity Revisited

    NASA Astrophysics Data System (ADS)

    Lorenz, R. D.

    2003-05-01

    Determinations of the relative humidity of methane near Titan's surface range from 40-60 %. The rationale advanced by Lunine in the global ocean hypothesis was that a mixed ethane-methane ocean in thermodynamic equilibrium with the atmosphere would be unsaturated due to methane vapor pressure supression by involatile ethane (much as salt or sugar dissolved in water slows its evaporation). Here I explore a nonequilibrium explanation for the incomplete saturation - the reason why the terrestrial atmosphere is not saturated. Specifically, saturated near-surface air is mixed with downwelling dry air, a mixing driven by vertical convection. The more vigorous the mixing, the dryer the near-surface air should be. Flasar (1983) made a crude empirical evaluation of transport processes : here I adopt a more fundamental thermodynamic approach. In reality both the involatile solute and the mixing mechanisms probably play a part in regulating methane humidity, and the utility of global and annual averages must be compromised by latitudinal and seasonal dependences. Comparison with the Earth - where moist processes play a dominant role in the entropy budget - will be instructive.

  16. Humidity Testing for Human Rated Spacecraft

    NASA Technical Reports Server (NTRS)

    Johnson, Gary B.

    2009-01-01

    Determination that equipment can operate in and survive exposure to the humidity environments unique to human rated spacecraft presents widely varying challenges. Equipment may need to operate in habitable volumes where the atmosphere contains perspiration, exhalation, and residual moisture. Equipment located outside the pressurized volumes may be exposed to repetitive diurnal cycles that may result in moisture absorption and/or condensation. Equipment may be thermally affected by conduction to coldplate or structure, by forced or ambient air convection (hot/cold or wet/dry), or by radiation to space through windows or hatches. The equipment s on/off state also contributes to the equipment s susceptibility to humidity. Like-equipment is sometimes used in more than one location and under varying operational modes. Due to these challenges, developing a test scenario that bounds all physical, environmental and operational modes for both pressurized and unpressurized volumes requires an integrated assessment to determine the "worst-case combined conditions." Such an assessment was performed for the Constellation program, considering all of the aforementioned variables; and a test profile was developed based on approximately 300 variable combinations. The test profile has been vetted by several subject matter experts and partially validated by testing. Final testing to determine the efficacy of the test profile on actual space hardware is in the planning stages. When validation is completed, the test profile will be formally incorporated into NASA document CxP 30036, "Constellation Environmental Qualification and Acceptance Testing Requirements (CEQATR)."

  17. Breadboard CO2 and humidity control system

    NASA Technical Reports Server (NTRS)

    Boehm, A. M.

    1976-01-01

    A regenerable CO2 and humidity control system is being developed for potential use on shuttle as an alternate to the baseline lithium hydroxide (LiOH)/condensing heat exchanger system. The system utilizes a sorbent material, designated HS-C, to adsorb CO2 and water vapor from the cabin atmosphere. The material is regenerated by exposing it to space vacuum. A half-size breadboard system, utilizing a flight representative HS-C canister, was designed, built, and performance tested to shuttle requirements for total CO2 and total humidity removal. The use of a new chemical matrix material allowed significant optimization of the system design by packing the HS-C chemical into the core of a heat exchanger which is manifolded to form two separate and distinct beds. Breadboard system performance was proven by parametric testing and simulated mission testing over the full range of shuttle crew sizes and metabolic loadings. Vacuum desorption testing demonstrated considerable savings in previously projected shuttle vacuum duct sizing.

  18. Black versus Black: The Relationship among African, African American, and African Caribbean Persons.

    ERIC Educational Resources Information Center

    Jackson, Jennifer V.; Cothran, Mary E.

    2003-01-01

    Surveyed people of African descent regarding relationships among African, African-American, and African-Caribbean persons, focusing on contact and friendship, travel to countries of the diaspora, cross-cultural communication, thoughts and stereotypes, and education. Most respondents had contacts with the other groups, but groups had preconceived…

  19. Ultrafast response humidity sensor using supramolecular nanofibre and its application in monitoring breath humidity and flow

    NASA Astrophysics Data System (ADS)

    Mogera, Umesha; Sagade, Abhay A.; George, Subi J.; Kulkarni, Giridhar U.

    2014-02-01

    Measuring humidity in dynamic situations calls for highly sensitive fast response sensors. Here we report, a humidity sensor fabricated using solution processed supramolecular nanofibres as active resistive sensing material. The nanofibres are built via self- assembly of donor and acceptor molecules (coronene tetracarboxylate and dodecyl methyl viologen respectively) involved in charge transfer interactions. The conductivity of the nanofibre varied sensitively over a wide range of relative humidity (RH) with unprecedented fast response and recovery times. Based on UV-vis, XRD and AFM measurements, it is found that the stacking distance in the nanofibre decreases slightly while the charge transfer band intensity increases, all observations implying enhanced charge transfer interaction and hence the conductivity. It is demonstrated to be as a novel breath sensor which can monitor the respiration rate. Using two humidity sensors, a breath flow sensor was made which could simultaneously measure RH and flow rate of exhaled nasal breath. The integrated device was used for monitoring RH in the exhaled breath from volunteers undergoing exercise and alcohol induced dehydration.

  20. Ultrafast response humidity sensor using supramolecular nanofibre and its application in monitoring breath humidity and flow

    PubMed Central

    Mogera, Umesha; Sagade, Abhay A.; George, Subi J.; Kulkarni, Giridhar U.

    2014-01-01

    Measuring humidity in dynamic situations calls for highly sensitive fast response sensors. Here we report, a humidity sensor fabricated using solution processed supramolecular nanofibres as active resistive sensing material. The nanofibres are built via self- assembly of donor and acceptor molecules (coronene tetracarboxylate and dodecyl methyl viologen respectively) involved in charge transfer interactions. The conductivity of the nanofibre varied sensitively over a wide range of relative humidity (RH) with unprecedented fast response and recovery times. Based on UV-vis, XRD and AFM measurements, it is found that the stacking distance in the nanofibre decreases slightly while the charge transfer band intensity increases, all observations implying enhanced charge transfer interaction and hence the conductivity. It is demonstrated to be as a novel breath sensor which can monitor the respiration rate. Using two humidity sensors, a breath flow sensor was made which could simultaneously measure RH and flow rate of exhaled nasal breath. The integrated device was used for monitoring RH in the exhaled breath from volunteers undergoing exercise and alcohol induced dehydration. PMID:24531132

  1. Indirect health effects of relative humidity in indoor environments

    SciTech Connect

    Arundel, A.V.; Sterling, E.M.; Biggin, J.H.; Sterling, T.D.

    1986-03-01

    A review of the health effects of relative humidity in indoor environments suggests that relative humidity can affect the incidence of respiratory infections and allergies. Experimental studies on airborne-transmitted infectious bacteria and viruses have shown that the survival or infectivity of these organisms is minimized by exposure to relative humidities between 40 and 70%. Nine epidemiological studies examined the relationship between the number of respiratory infections or absenteeism and the relative humidity of the office, residence, or school. The incidence of absenteeism or respiratory infections was found to be lower among people working or living in environments with mid-range versus low or high relative humidities. The indoor size of allergenic mite and fungal populations is directly dependent upon the relative humidity. Mite populations are minimized when the relative humidity is below 50% and reach a maximum size at 80% relative humidity. Most species of fungi cannot grow unless the relative humidity exceeds 60%. Relative humidity also affects the rate of offgassing of formaldehyde from indoor building materials, the rate of formation of acids and salts from sulfur and nitrogen dioxide, and the rate of formation of ozone. The influence of relative humidity on the abundance of allergens, pathogens, and noxious chemicals suggests that indoor relative humidity levels should be considered as a factor of indoor air quality. The majority of adverse health effects caused by relative humidity would be minimized by maintaining indoor levels between 40 and 60%. This would require humidification during winter in areas with cold winter climates. Humidification should preferably use evaporative or steam humidifiers, as cool mist humidifiers can disseminate aerosols contaminated with allergens.

  2. Indirect health effects of relative humidity in indoor environments.

    PubMed Central

    Arundel, A V; Sterling, E M; Biggin, J H; Sterling, T D

    1986-01-01

    A review of the health effects of relative humidity in indoor environments suggests that relative humidity can affect the incidence of respiratory infections and allergies. Experimental studies on airborne-transmitted infectious bacteria and viruses have shown that the survival or infectivity of these organisms is minimized by exposure to relative humidities between 40 and 70%. Nine epidemiological studies examined the relationship between the number of respiratory infections or absenteeism and the relative humidity of the office, residence, or school. The incidence of absenteeism or respiratory infections was found to be lower among people working or living in environments with mid-range versus low or high relative humidities. The indoor size of allergenic mite and fungal populations is directly dependent upon the relative humidity. Mite populations are minimized when the relative humidity is below 50% and reach a maximum size at 80% relative humidity. Most species of fungi cannot grow unless the relative humidity exceeds 60%. Relative humidity also affects the rate of offgassing of formaldehyde from indoor building materials, the rate of formation of acids and salts from sulfur and nitrogen dioxide, and the rate of formation of ozone. The influence of relative humidity on the abundance of allergens, pathogens, and noxious chemicals suggests that indoor relative humidity levels should be considered as a factor of indoor air quality. The majority of adverse health effects caused by relative humidity would be minimized by maintaining indoor levels between 40 and 60%. This would require humidification during winter in areas with cold winter climates. Humidification should preferably use evaporative or steam humidifiers, as cool mist humidifiers can disseminate aerosols contaminated with allergens. PMID:3709462

  3. Irregular Periods

    MedlinePlus

    ... number of days after the last one. The Menstrual Cycle Most girls get their first period between the ... to skip periods or to have an irregular menstrual cycle. Illness, rapid weight change, or stress can also ...

  4. NW African hydrology and vegetation during the Last Glacial cycle reflected in plant-wax-specific hydrogen and carbon isotopes

    NASA Astrophysics Data System (ADS)

    Kuechler, R. R.; Schefuß, E.; Beckmann, B.; Dupont, L.; Wefer, G.

    2013-12-01

    We present a hydrologic reconstruction of the Sahara-Sahel transition, covering the complete Last Glacial cycle (130 ka), based on a combination of plant-wax-specific hydrogen (δD) and carbon isotopes (δ13C). The δD and δ13C signatures of long-chain n-alkanes from ODP Site 659 off NW Africa reveal a significant anti-correlation. Complementary to published pollen data, we infer that this plant-wax signal reflects sensitive responses of the vegetation cover to precipitation changes in the Sahel region, as well as varying contributions from biomes north of the Sahara (C3 domain) by North-East Trade Winds (NETW). During arid phases, especially the northern parts of the Sahel likely experienced crucial water stress, which resulted in a pronounced contraction of the vegetation cover, thus reducing the amount of C4 plant waxes from the region. The increase in NETW strength during dry periods further promoted a more pronounced C3-plant-wax signal derived from the North African C3 plant domain. During humid periods, the C4-dominated Sahelian environments spread northward into the Saharan realm, in association with lower NETW inputs of C3 plant waxes. Arid-humid cycles deduced from plant-wax δD are in accordance with concomitant changes in weathering intensity reflected in varying major element distributions. Environmental shifts are generally linked to periods with large fluctuations in Northern Hemisphere summer insolation. During Marine Isotope Stages 2 and 3, when insolation variability was low, coupling of the hydrologic regime to alkenone-based estimates of NE Atlantic sea-surface temperatures becomes apparent.

  5. Astronomy for African development

    NASA Astrophysics Data System (ADS)

    Govender, Kevindran

    2011-06-01

    In recent years there have been a number of efforts across Africa to develop the field of astronomy as well as to reap benefit from astronomy for African people. This presentation will discuss the case of the SALT (Southern African Large Telescope) Collateral Benefits Programme (SCBP) which was set up to ensure societal benefit from astronomy. With African society as the target, the SCBP has embarked on various projects from school level education to public understanding of science to socio-economic development, the latter mainly being felt in the rural communities surrounding the South African Astronomical Observatory (home to SALT). A development plan for ``Astronomy in Africa'' will also be discussed. This plan has been drawn up with input from all over Africa and themed ``Astronomy for Education''. The Africa case stands as a good example for the IYA cornerstone project ``Developing Astronomy Globally'' which focuses on developing regions.

  6. African American Suicide

    MedlinePlus

    ... accounted for 83.8% of Caucasian elderly suicides. • Firearms were the predominant method of suicide among African ... per 100,000 annually. Source: Centers for Disease Control and Prevention. National Vital Statistics System. Mortality Data. ...

  7. Origins of streamflow in a crystalline basement catchment in a sub-humid Sudanian zone: The Donga basin (Benin, West Africa): Inter-annual variability of water budget

    NASA Astrophysics Data System (ADS)

    Séguis, L.; Kamagaté, B.; Favreau, G.; Descloitres, M.; Seidel, J.-L.; Galle, S.; Peugeot, C.; Gosset, M.; Le Barbé, L.; Malinur, F.; Van Exter, S.; Arjounin, M.; Boubkraoui, S.; Wubda, M.

    2011-05-01

    SummaryDuring the last quarter of the 20th century, West Africa underwent a particularly intense and generalized drought. During this period, the biggest drops in streamflow were observed in the Sudanian zone rather than in the Sahelian zone, but the reasons are still poorly understood. In 2000, a meso-scale hydrological observatory was set up in the sub-humid Sudanian zone of the Upper Ouémé Valley (Benin). Three embedded catchments of 12-586 km 2 located on a crystalline bedrock were intensively instrumented to document the different terms of the water budget and to identify the main streamflow generating processes and base-flow mechanisms at different scales. Geophysical, hydrological and geochemical data were collected throughout the catchments from 2002 to 2006. Crossing these data helped define their hydrological functioning. The region has seasonal streamflow, and the permanent groundwater in the weathered mantle does not drain to rivers, instead, seasonal perched groundwaters are the major contributor to annual streamflow. The perched groundwaters are mainly located in seasonally waterlogged sandy layers in the headwater bottom-lands called bas-fonds in French-speaking West Africa of 1st order streams. During the period 2003-2006, regolith groundwater recharge ranged between 10% and 15% of the annual rainfall depth. Depletion of permanent groundwater during the dry season is probably explained by local evapotranspiration which was seen not to be limited to gallery forests. During the 4-year study period, a reduction of 20% in annual rainfall led to a 50% reduction in streamflow. This reduction was observed in the two components of the flow: direct runoff and drainage of perched groundwater. Thanks to the comprehensive dataset obtained, the results obtained for the Donga experimental catchment are now being extrapolated to the whole upper Ouémé valley, which can be considered as representative of sub-humid Sudanian rivers flowing on a crystalline

  8. A CMOS Humidity Sensor for Passive RFID Sensing Applications

    PubMed Central

    Deng, Fangming; He, Yigang; Zhang, Chaolong; Feng, Wei

    2014-01-01

    This paper presents a low-cost low-power CMOS humidity sensor for passive RFID sensing applications. The humidity sensing element is implemented in standard CMOS technology without any further post-processing, which results in low fabrication costs. The interface of this humidity sensor employs a PLL-based architecture transferring sensor signal processing from the voltage domain to the frequency domain. Therefore this architecture allows the use of a fully digital circuit, which can operate on ultra-low supply voltage and thus achieves low-power consumption. The proposed humidity sensor has been fabricated in the TSMC 0.18 μm CMOS process. The measurements show this humidity sensor exhibits excellent linearity and stability within the relative humidity range. The sensor interface circuit consumes only 1.05 μW at 0.5 V supply voltage and reduces it at least by an order of magnitude compared to previous designs. PMID:24841250

  9. A CMOS humidity sensor for passive RFID sensing applications.

    PubMed

    Deng, Fangming; He, Yigang; Zhang, Chaolong; Feng, Wei

    2014-01-01

    This paper presents a low-cost low-power CMOS humidity sensor for passive RFID sensing applications. The humidity sensing element is implemented in standard CMOS technology without any further post-processing, which results in low fabrication costs. The interface of this humidity sensor employs a PLL-based architecture transferring sensor signal processing from the voltage domain to the frequency domain. Therefore this architecture allows the use of a fully digital circuit, which can operate on ultra-low supply voltage and thus achieves low-power consumption. The proposed humidity sensor has been fabricated in the TSMC 0.18 μm CMOS process. The measurements show this humidity sensor exhibits excellent linearity and stability within the relative humidity range. The sensor interface circuit consumes only 1.05 µW at 0.5 V supply voltage and reduces it at least by an order of magnitude compared to previous designs. PMID:24841250

  10. Influence of humidity on hot-wire measurements

    NASA Astrophysics Data System (ADS)

    Durst, Franz; Noppenberger, Stefan; Still, Martin; Venzke, Holger

    1996-10-01

    When applying hot-wire anemometry to velocity measurements in air, it is standard practice to neglect the effect of humidity. In this paper the influence of the thermodynamic and transport properties of humid air on hot-wire measurements is examined on the basis of the correlations for Nusselt number proposed previously by other researchers. Experimental results at controlled levels of relative humidity between 30% and 90% at 0957-0233/7/10/021/img1, 0957-0233/7/10/021/img2 and 0957-0233/7/10/021/img3 are reproduced satisfactorily by the theoretical approaches of two of these equations. A corrective term is defined to expand formulae designed for dry air to work in a humid environment. The error in velocity by omitting the influence of humidity is estimated in terms of temperature and relative humidity.

  11. Increased molecular mobility in humid silk fibers under tensile stress

    NASA Astrophysics Data System (ADS)

    Seydel, Tilo; Knoll, Wiebke; Greving, Imke; Dicko, Cedric; Koza, Michael M.; Krasnov, Igor; Müller, Martin

    2011-01-01

    Silk fibers are semicrystalline nanocomposite protein fibers with an extraordinary mechanical toughness that changes with humidity. Diffusive or overdamped motion on a molecular level is absent in dry silkworm silk, but present in humid silk at ambient temperature. This microscopic diffusion distinctly depends on the externally applied macroscopic tensile force. Quasielastic and inelastic neutron-scattering data as a function of humidity and of tensile strain on humid silk fibers support the model that both the adsorbed water and parts of the amorphous polymers participate in diffusive motion and are affected by the tensile force. It is notable that the quasielastic linewidth of humid silk at 100% relative humidity increases significantly with the applied force. The effect of the tensile force is discussed in terms of an increasing alignment of the polymer chains in the amorphous fraction with increasing tensile stress which changes the geometrical restrictions of the diffusive motions.

  12. Sampling at controlled relative humidity with a cascade impactor

    NASA Astrophysics Data System (ADS)

    Vasiliou, Joseph G.; Sorensen, Diana; McMurry, Peter H.

    The design and function of a device that regulates the relative humidity of an ambient aerosol sample is described. We use this RH controller upstream of MOUDI impactors to permit sampling at relative humidities in the 70-80% range. Humidity control is achieved by allowing the aerosol to approach equilibrium with a saturated salt solution. Benefits to sampling with impactors in this relative humidity range include greatly reduced bounce of fine, hygroscopic particles, minimal flow-induced sizing errors, and minimization of uncertainties in measured size distributions due to diurnal variations in relative humidity during sampling. Data from field measurements in a humid environment (Look Rock, TN) and arid environments (Las Vegas, NV and Meadview, AZ) are discussed.

  13. A Standard CMOS Humidity Sensor without Post-Processing

    PubMed Central

    Nizhnik, Oleg; Higuchi, Kohei; Maenaka, Kazusuke

    2011-01-01

    A 2 μW power dissipation, voltage-output, humidity sensor accurate to 5% relative humidity was developed using the LFoundry 0.15 μm CMOS technology without post-processing. The sensor consists of a woven lateral array of electrodes implemented in CMOS top metal, a Intervia Photodielectric 8023–10 humidity-sensitive layer, and a CMOS capacitance to voltage converter. PMID:22163949

  14. Uplift of the South African Plateau: mantle-scale deformation, long wavelength relief growth and offshore sediment budget

    NASA Astrophysics Data System (ADS)

    Guillocheau, François; Dauteuil, Olivier; Baby, Guillaume; Robin, Cécile

    2013-04-01

    The South African Plateau is one of the largest very long wavelength relief (x1000 km) of the world that could be related to mantle dynamics and the effect of the African superplume. Unfortunately, the timing of the uplift and the different steps of the relief growth are still debated with a Late Cretaceous uplift scenario and an Oligocene one. Whatever model, few attentions were paid to the evolution of the overall geomorphic system, from the upstream erosional system to the downstream depositional system. This study is based, onshore, on the mapping and chronology of all the macroforms (weathering surfaces and associated alterites, pediments and pediplains, incised rivers, wave-cut platforms) dated by intersection with the few preserved sediments and the volcanics (mainly kimberlites pipes) and, offshore, on a more classical dataset of seismic lines and petroleum wells (characterization and dating of forced regression, sediment volume measurement, etc..). The main result of this study is that the South African Plateau is an old Late Cretaceous Plateau reactivated during Paleogene times and fossilized since the Middle Miocene. • During Late Cretaceous, in a semiarid climatic setting, the main uplift occurred from the east (around 95 Ma) to the west (around 75 Ma) and could result from the migration of the African plate over the African superplume: This is the paroxysm of the erosion with the growth of a large delta offshore present-day Orange River mouth (sedimentation rate around 100 000 km3/Ma). • During Paleocene - Mid Eocene times, in more humid conditions and in response to a more subtle long wavelength deformation, pedimentation occurred mainly localised along Cape Fold Belt feeding a large delta offshore western Cape Peninsula. During Mid Eocene times, all those landscapes are fossilized and weathered by laterites. • Late Eocene and Oligocene is the second period of uplift of the Plateau, localised along its Indian Ocean side (Drackensberg Moutains

  15. Leaky nitrogen cycle in pristine African montane rainforest soil

    NASA Astrophysics Data System (ADS)

    Rütting, Tobias; Cizungu Ntaboba, Landry; Roobroeck, Dries; Bauters, Marijn; Huygens, Dries; Boeckx, Pascal

    2015-10-01

    Many pristine humid tropical forests show simultaneously high nitrogen (N) richness and sustained loss of bioavailable N forms. To better understand this apparent upregulation of the N cycle in tropical forests, process-based understanding of soil N transformations, in geographically diverse locations, remains paramount. Field-based evidence is limited and entirely lacking for humid tropical forests on the African continent. This study aimed at filling both knowledge gaps by monitoring N losses and by conducting an in situ 15N labeling experiment in the Nyungwe tropical montane forest in Rwanda. Here we show that this tropical forest shows high nitrate (NO3-) leaching losses, confirming findings from other parts of the world. Gross N transformation rates point to an open soil N cycle with mineralized N nitrified rather than retained via immobilization; gross immobilization of NH4+ and NO3- combined accounted for 37% of gross mineralization, and plant N uptake is dominated by ammonium (NH4+). This study provided new process understanding of soil N cycling in humid tropical forests and added geographically independent evidence that humid tropical forests are characterized by soil N dynamics and N inputs sustaining bioavailable N loss.

  16. Homogenization of global radiosonde humidity data

    NASA Astrophysics Data System (ADS)

    Blaschek, Michael; Haimberger, Leopold

    2016-04-01

    The global radiosonde network is an important source of upper-air measurements and is strongly connected to reanalysis efforts of the 20th century. However, measurements are strongly affected by changes in the observing system and require a homogenization before they can be considered useful in climate studies. In particular humidity measurements are known to show spurious trends and biases induced by many sources, e.g. reporting practices or freezing of the sensor. We propose to detect and correct these biases in an automated way, as has been done with temperature and winds. We detect breakpoints in dew point depression (DPD) time series by employing a standard normal homogeneity test (SNHT) on DPD-departures from ERA-Interim. In a next step, we calculate quantile departures between the latter and the earlier part near the breakpoints of the time series, going back in time. These departures adjust the earlier distribution of DPD to the latter distribution, called quantile matching, thus removing for example a non climatic shift. We employ this approach to the existing radiosonde network. In a first step to verify our approach we compare our results with ERA-Interim data and brightness temperatures of humidity-sensitive channels of microwave measuring radiometers (SSMIS) onboard DMSP F16. The results show that some of the biases can be detected and corrected in an automated way, however large biases that impact the distribution of DPD values originating from known reporting practices (e.g. 30 DPD on US stations) remain. These biases can be removed but not corrected. The comparison of brightness temperatures from satellite and radiosondes proofs to be difficult as large differences result from for example representative errors.

  17. Software Compensates Electronic-Nose Readings for Humidity

    NASA Technical Reports Server (NTRS)

    Zhou, Hanying

    2007-01-01

    A computer program corrects for the effects of humidity on the readouts of an array of chemical sensors (an "electronic nose"). To enable the use of this program, the array must incorporate an independent humidity sensor in addition to sensors designed to detect analytes other than water vapor. The basic principle of the program was described in "Compensating for Effects of Humidity on Electronic Noses" (NPO-30615), NASA Tech Briefs, Vol. 28, No. 6 (June 2004), page 63. To recapitulate: The output of the humidity sensor is used to generate values that are subtracted from the outputs of the other sensors to correct for contributions of humidity to those readings. Hence, in principle, what remains after corrections are the contributions of the analytes only. The outputs of the non-humidity sensors are then deconvolved to obtain the concentrations of the analytes. In addition, the humidity reading is retained as an analyte reading in its own right. This subtraction of the humidity background increases the ability of the software to identify such events as spills in which contaminants may be present in small concentrations and accompanied by large changes in humidity.

  18. Do honeybees, Apis mellifera scutellata, regulate humidity in their nest?

    NASA Astrophysics Data System (ADS)

    Human, Hannelie; Nicolson, Sue W.; Dietemann, Vincent

    2006-08-01

    Honeybees are highly efficient at regulating the biophysical parameters of their hive according to colony needs. Thermoregulation has been the most extensively studied aspect of nest homeostasis. In contrast, little is known about how humidity is regulated in beehives, if at all. Although high humidity is necessary for brood development, regulation of this parameter by honeybee workers has not yet been demonstrated. In the past, humidity was measured too crudely for a regulation mechanism to be identified. We reassess this issue, using miniaturised data loggers that allow humidity measurements in natural situations and at several places in the nest. We present evidence that workers influence humidity in the hive. However, there are constraints on potential regulation mechanisms because humidity optima may vary in different locations of the nest. Humidity could also depend on variable external factors, such as water availability, which further impair the regulation. Moreover, there are trade-offs with the regulation of temperature and respiratory gas exchanges that can disrupt the establishment of optimal humidity levels. As a result, we argue that workers can only adjust humidity within sub-optimal limits.

  19. Climate change, humidity, and mortality in the United States

    PubMed Central

    Barreca, Alan I.

    2014-01-01

    This paper estimates the effects of humidity and temperature on mortality rates in the United States (c. 1973–2002) in order to provide an insight into the potential health impacts of climate change. I find that humidity, like temperature, is an important determinant of mortality. Coupled with Hadley CM3 climate-change predictions, I project that mortality rates are likely to change little on the aggregate for the United States. However, distributional impacts matter: mortality rates are likely to decline in cold and dry areas, but increase in hot and humid areas. Further, accounting for humidity has important implications for evaluating these distributional effects. PMID:25328254

  20. Mesoscale variability of free tropospheric humidity near San Nicolas Island during FIRE

    NASA Technical Reports Server (NTRS)

    White, A. B.; Fairall, C. W.; Thomson, D. W.

    1990-01-01

    Humidity variability at the top of the marine boundary layer (MBL) and in the free troposphere was examined using a variety of measurements taken on and around San Nicolas Island (SNI) during the FIRE IFO in July, 1987. Doppler wind profiler reflectivity recorded at two minute time resolution has provided the most continuous record and detail of small scale humidity fluctuations. Rawinsonde data were available from both an island site and the research vessel Point Sur. The information extractable from these sources is somewhat limited due to the frequency of launches (3 to 4/day at SNI and 6/day on the Point Sur). Some additional data were available from instrumented aircraft although scheduling flights in the neighborhood of the island was difficult due to restrictions on the air space. Other relevant data were collected at SNI near the radar and rawinsonde launch sites. A continuous record of cloud base altitude was logged by a ceilometer. Doppler acoustic sounder (sodar) reflectivity data provided a good record of inversion height. The sodar also monitored turbulent temperature fluctuations in the MBL. A small ground station recorded hourly averages of solar irradiance and downward longwave irradiance. The analysis in progress of the various data sets for two adjacent two day periods from 11 July to 14 July is described. The earlier period was chosen because the marine inversion was unusually high and there was increased frequency of rawinsonde launches at SNI. The later period was chosen because of the significant descent with time of an elevated inversion indicated by the radar data. Throughout the four day period, but especially in the first half, the turbulent humidity structure calculated from Doppler radar reflectivity shows excellent agreement with humidity profiles evaluated from rawinsonde data.

  1. Indoor humidity and human health. Part 1: Literature review of health effects of humidity-influenced indoor pollutants

    SciTech Connect

    Baughman, A.V.; Arens, E.A.

    1996-11-01

    Standards for indoor thermal conditions and ventilation include upper limits for relative humidity (RH) that typically are in the range of 60% to 80% RH. Although the reasons for the limits are often not explicitly stated, it is generally known that they were set out of concern for the health effects that might occur should the humidity become too high. The primary health effects of high humidity are caused by the growth and spread of biotic agents, although humidity interactions with nonbiotic pollutants, such as formaldehyde, may also cause adverse effects. This literature review identifies the most important health issues associated with high humidities and presents humidity requirements, typical contamination sites within buildings, and remediation measures for each pollutant. Part two of the paper addresses the physical causes of moisture-related problems in buildings.

  2. Applications of LPG fiber optical sensors for relative humidity and chemical-warfare-agents monitoring

    NASA Astrophysics Data System (ADS)

    Luo, Shufang; Liu, Yongcheng; Sucheta, Artur; Evans, Mishell K.; Van Tassell, Roger

    2002-09-01

    A long-period grating (LPG) fiber optic sensor has been developed for monitoring the relative humidity levels and toxic chemicals, especially the chemical warfare agents. The principle of operation of this sensor is based on monitoring the refractive index changes exhibited by the reactive coating applied to the surface of the LPG region in response to analytes. Specific interaction of the analyte with the thin film polymer coating produces as the output a wavelength shift that can be correlated with the concentration of the analyte. Thin polymer coating for relative humidity sensor is made of carboxymethylcellulose (CMC) covalently bound to the surface of the fiber. Coating for chemical warfare agent detection employs metal nanoclusters imbedded in polyethylenimine (PEI) for specific reaction. The relative humidity level can be determined from 0% to 95% and the level of toxic chemicals can be determined is at least on the scale of 1 ppm. This small-size and low-cost LPG fiber optic sensor exhibited high sensitivity, rapid response, repeatability and durability. The goal of developing relative humidity sensor is to produce a fiber optic sensor-based health monitoring system for building, while the chemical sensor has found its application in point detection network for chemical warfare agent monitoring.

  3. A microscopy study of hyphal growth of Penicillium rubens on gypsum under dynamic humidity conditions.

    PubMed

    van Laarhoven, Karel A; Huinink, Hendrik P; Adan, Olaf C G

    2016-05-01

    To remediate indoor fungal growth, understanding the moisture relations of common indoor fungi is crucial. Indoor moisture conditions are commonly quantified by the relative humidity (RH). RH is a major determinant of the availability of water in porous indoor surfaces that fungi grow on. The influence of steady-state RH on growth is well understood. Typically, however, the indoor RH constantly changes so that fungi have to endure frequent periods of alternating low and high RH. Knowledge of how common indoor fungi survive and are affected by the low-RH periods is limited. In particular, the specific effects of a drop in RH on the growth of the mycelium remain unclear. In this work, video microscopy was used to monitor hyphal growth of Penicillium rubens on gypsum substrates under controlled dynamic humidity conditions. The effect of a single period of low RH (RH = 50-90%) interrupting favourable conditions (RH = 97%) was tested. It was found that hyphal tips ceased to extend when exposed to any tested decrease in RH. However, new hyphal growth always emerges, seemingly from the old mycelium, suggesting that this indoor fungus does not rely only on conidia to survive the humidity patterns considered. These findings are a fundamental step in unravelling the effect of RH on indoor fungal growth. PMID:26996401

  4. Dark current measurements in humid SF6: influence of electrode roughness, relative humidity and pressure

    NASA Astrophysics Data System (ADS)

    Zavattoni, L.; Hanna, R.; Lesaint, O.; Gallot-Lavallée, O.

    2015-09-01

    The measurement of ‘dark current’ in pressurized SF6 at high electric field is performed using electrodes with a coaxial geometry. To identify the main mechanisms involved in measured currents, the influences of electrode roughness, gas pressure and relative humidity have been investigated. The experimental results reveal that charge injection from the electrode constitute the predominant process responsible for the dark current. The latter is nearly identical in positive and negative polarities, and shows an exponential increase versus the relative humidity and the electric field. The analysis of results shows that under high electric field, the emission of charged water clusters from the water films adsorbed on electrodes probably constitutes the main mechanism of charge emission.

  5. Entheseal changes and sexual division of labor in a North-African population: The case of the pre-Hispanic period of the Gran Canaria Island (11th-15th c. CE).

    PubMed

    Santana-Cabrera, J; Velasco-Vázquez, J; Rodríguez-Rodríguez, A

    2015-04-01

    The aim of this paper is to investigate the relationship between entheseal changes and sexual division of labor in the pre-Hispanic population of Gran Canaria Island (Spain). Ethnohistorical records from the period of contact between Europeans and the Canarian indigenous population provide rich information about the different activities performed by men and women. For this purpose, entheseal changes in a sample of 138 individuals (82 males and 56 females) buried in ten pre-Hispanic cemeteries (11th and 15th centuries cal. CE) were analyzed. Forty-one entheses located in the clavicle, humerus, ulna and radius were analyzed (fibrous and fibro-cartilaginous attachment sites). Entheses were graded using a visual and descriptive standard which summarized the entheseal changes. This method interprets the changes as a sign of robustness on a scale from low to high development and includes enthesopathies. The intra- and inter-observer error of this method was minimal. Sex differences in the degree of robustness, bilateral asymmetry, sexual dimorphism and principal components analyses were tested in this sample. The results indicate significant variance in the entheseal robustness between males and females. They also suggest the impact of certain biomechanical chains (pronosupination, shoulder rotation, etc.) in entheseal changes. These results contribute to an interdisciplinary approach to the study of the sexual division of labor in the pre-Hispanic society of Gran Canaria. PMID:25701082

  6. The relationship between indoor and outdoor temperature, apparent temperature, relative humidity, and absolute humidity.

    PubMed

    Nguyen, J L; Schwartz, J; Dockery, D W

    2014-02-01

    Many studies report an association between outdoor ambient weather and health. Outdoor conditions may be a poor indicator of personal exposure because people spend most of their time indoors. Few studies have examined how indoor conditions relate to outdoor ambient weather. The average indoor temperature, apparent temperature, relative humidity (RH), and absolute humidity (AH) measured in 16 homes in Greater Boston, Massachusetts, from May 2011 to April 2012 was compared to measurements taken at Boston Logan airport. The relationship between indoor and outdoor temperatures is nonlinear. At warmer outdoor temperatures, there is a strong correlation between indoor and outdoor temperature (Pearson correlation coefficient, r = 0.91, slope, β = 0.41), but at cooler temperatures, the association is weak (r = 0.40, β = 0.04). Results were similar for outdoor apparent temperature. The relationships were linear for RH and AH. The correlation for RH was modest (r = 0.55, β = 0.39). Absolute humidity exhibited the strongest indoor-to-outdoor correlation (r = 0.96, β = 0.69). Indoor and outdoor temperatures correlate well only at warmer outdoor temperatures. Outdoor RH is a poor indicator of indoor RH, while indoor AH has a strong correlation with outdoor AH year-round. PMID:23710826

  7. Low-frequency variations in surface atmospheric humidity, temperature, and precipitation: Inferences from reanalyses and monthly gridded observational data sets

    NASA Astrophysics Data System (ADS)

    Simmons, A. J.; Willett, K. M.; Jones, P. D.; Thorne, P. W.; Dee, D. P.

    2010-01-01

    Evidence is presented of a reduction in relative humidity over low-latitude and midlatitude land areas over a period of about 10 years leading up to 2008, based on monthly anomalies in surface air temperature and humidity from comprehensive European Centre for Medium-Range Weather Forecasts reanalyses (ERA-40 and ERA-Interim) and from Climatic Research Unit and Hadley Centre analyses of monthly station temperature data (CRUTEM3) and synoptic humidity observations (HadCRUH). The data sets agree well for both temperature and humidity variations for periods and places of overlap, although the average warming over land is larger for the fully sampled ERA data than for the spatially and temporally incomplete CRUTEM3 data. Near-surface specific humidity varies similarly over land and sea, suggesting that the recent reduction in relative humidity over land may be due to limited moisture supply from the oceans, where evaporation has been limited by sea surface temperatures that have not risen in concert with temperatures over land. Continental precipitation from the reanalyses is compared with a new gauge-based Global Precipitation Climatology Centre (GPCC) data set, with the combined gauge and satellite products of the Global Precipitation Climatology Project (GPCP) and the Climate Prediction Center (CPC), Merged Analysis of Precipitation (CMAP), and with CPC's independent gauge analysis of precipitation over land (PREC/L). The reanalyses agree best with the new GPCC and latest GPCP data sets, with ERA-Interim significantly better than ERA-40 at capturing monthly variability. Shifts over time in the differences among the precipitation data sets make it difficult to assess their longer-term variations and any link with longer-term variations in humidity.

  8. African-Americans and Alzheimer's

    MedlinePlus

    ... Share Plus on Google Plus African-Americans and Alzheimer's alz.org | IHaveAlz Introduction 10 Warning Signs Brain ... African-Americans are at a higher risk for Alzheimer's disease. Many Americans dismiss the warning signs of ...

  9. Measuring Humidity in Sealed Glass Encasements

    NASA Technical Reports Server (NTRS)

    West, James W.; Burkett, Cecil G.; Levine, Joel S.

    2005-01-01

    A technique has been devised for measuring the relative humidity levels in the protective helium/water vapor atmosphere in which the Declaration of Independence, the United States Constitution, and the Bill of Rights are encased behind glass panels on display at the National Archives in Washington, DC. The technique is noninvasive: it does not involve penetrating the encasements (thereby risking contamination or damage to the priceless documents) to acquire samples of the atmosphere. The technique could also be applied to similar glass encasements used to protect and display important documents and other precious objects in museums. The basic principle of the technique is straightforward: An encasement is maintained at its normal display or operating temperature (e.g., room temperature) while a portion of its glass front panel is chilled (see Figure 1) until condensed water droplets become visible on the inside of the panel. The relative humidity of the enclosed atmosphere can then be determined as a known function of the dew point, the temperature below which the droplets condense. Notwithstanding the straightforwardness of the basic principle, careful attention to detail is necessary to enable accurate determination of the dew point. In the initial application, the affected portion of the glass panel was cooled by contact with an aluminum plate that was cooled by a thermoelectric module, the exhaust heat of which was dissipated by a heat sink cooled by a fan. A thermocouple was used to measure the interior temperature of the aluminum plate, and six other thermocouples were used to measure the temperatures at six locations on the cooled outer surface of the glass panel (see Figure 2). Thermal grease was applied to the aluminum plate and the thermocouples to ensure close thermal contact. Power was supplied to the thermoelectric module in small increments, based on previous laboratory tests. A small flashlight and a magnifying glass were used to look for water

  10. Effect of relative humidity on fungal colonization of fiberglass insulation.

    PubMed Central

    Ezeonu, I M; Noble, J A; Simmons, R B; Price, D L; Crow, S A; Ahearn, D G

    1994-01-01

    Fiberglass duct liners and fiberglass duct boards from eight buildings whose occupants complained of unacceptable or moldy odors in the air were found to be heavily colonized by fungi, particularly by Aspergillus versicolor. Unused fiberglass was found to be susceptible to fungal colonization in environmental chambers dependent upon relative humidity. No colonization was observed at relative humidities below 50%. Images PMID:8031101

  11. Humidity-responsive starch-poly (methyl acrylate) films.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Blown films prepared from starch-poly(methyl acrylate) graft copolymers plasticized with urea and water display shrinkage at relative humidities greater than 50%. Shrinkage at relative humidities below approximately 75% is strongly correlated with the urea/starch weight ratio, which controls the eq...

  12. Temperature and humidity control of simulated human breath

    NASA Technical Reports Server (NTRS)

    Bartlett, R. G.; Hendricks, C. M.

    1972-01-01

    Subsystem was developed for breathing metabolic simulator which adjusts temperature and humidity of air to levels of human exhaled breath. Temperature-humidity subsystem is described, consisting of aluminum enclosure with 400 watt heat sheet glued to bottom, vertical separators, inlet connection, and check valve.

  13. Absolute Humidity and the Seasonality of Influenza (Invited)

    NASA Astrophysics Data System (ADS)

    Shaman, J. L.; Pitzer, V.; Viboud, C.; Grenfell, B.; Goldstein, E.; Lipsitch, M.

    2010-12-01

    Much of the observed wintertime increase of mortality in temperate regions is attributed to seasonal influenza. A recent re-analysis of laboratory experiments indicates that absolute humidity strongly modulates the airborne survival and transmission of the influenza virus. Here we show that the onset of increased wintertime influenza-related mortality in the United States is associated with anomalously low absolute humidity levels during the prior weeks. We then use an epidemiological model, in which observed absolute humidity conditions temper influenza transmission rates, to successfully simulate the seasonal cycle of observed influenza-related mortality. The model results indicate that direct modulation of influenza transmissibility by absolute humidity alone is sufficient to produce this observed seasonality. These findings provide epidemiological support for the hypothesis that absolute humidity drives seasonal variations of influenza transmission in temperate regions. In addition, we show that variations of the basic and effective reproductive numbers for influenza, caused by seasonal changes in absolute humidity, are consistent with the general timing of pandemic influenza outbreaks observed for 2009 A/H1N1 in temperate regions. Indeed, absolute humidity conditions correctly identify the region of the United States vulnerable to a third, wintertime wave of pandemic influenza. These findings suggest that the timing of pandemic influenza outbreaks is controlled by a combination of absolute humidity conditions, levels of susceptibility and changes in population mixing and contact rates.

  14. Acoustic method for measuring air temperature and humidity in rooms

    NASA Astrophysics Data System (ADS)

    Kanev, N. G.

    2014-05-01

    A method is proposed to determine air temperature and humidity in rooms with a system of sound sources and receivers, making it possible to find the sound velocity and reverberation time. Nomograms for determining the air temperature and relative air humidity are constructed from the found sound velocity and time reverberation values. The required accuracy of measuring these parameters is estimated.

  15. 40 CFR 86.344-79 - Humidity calculations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 18 2010-07-01 2010-07-01 false Humidity calculations. 86.344-79 Section 86.344-79 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS... Humidity calculations. (a) The following abbreviations (and units) are used in this section:...

  16. Effect of temperature and humidity on gestation length

    Technology Transfer Automated Retrieval System (TEKTRAN)

    High temperature and humidity have been shown to suppress daily milk and component yields of dairy cows, but their effects on most other performance traits have not been investigated. To determine if monthly differences in GL are caused by temperature and humidity, meteorological data since 1997 rec...

  17. Mars Science Laboratory (MSL) - First Results of Relative Humidity Observations

    NASA Astrophysics Data System (ADS)

    Genzer, Maria; Harri, Ari-Matti; Kemppinen, Osku; Gómez-Elvira, Javier; Renno, Nilton; Savijärvi, Hannu; Schmidt, Walter; Polkko, Jouni; Rodríquez-Manfredi, Jose Antonio; de la Torre Juárez, Manuel; Mischna, Michael; Martín-Torres, Javier; Haukka, Harri; Paz Zorzano-Mier, Maria; Rafkin, Scott; Paton, Mark; MSL Science Team

    2013-04-01

    The Mars Science laboratory (MSL) called Curiosity made a successful landing at Gale crater early August 2012. MSL has an environmental instrument package called the Rover Environmental Monitoring Station (REMS) as a part of its scientific payload. REMS comprises instrumentation for the observation of atmospheric pressure, temperature of the air, ground temperature, wind speed and direction, relative humidity, and UV measurements. The REMS instrument suite is described at length in [1]. We concentrate on describing the first results from the REMS relative humidity observations and comparison of the measurements with modeling results. The REMS humidity device is provided by the Finnish Meteorological Institute. It is based on polymeric capacitive humidity sensors developed by Vaisala Inc. The humidity device makes use of one transducer electronics section placed in the vicinity of the three (3) humidity sensor heads. The humidity device is mounted on the REMS boom 2 providing ventilation with the ambient atmosphere through a filter protecting the device from airborne dust. The absolute accuracy of the humidity device is temperature dependent, and is of the order of 2% at the temperature range of -30 to -10 °C, and of the order of 10% at the temperature range of -80 to -60 °C. This enables the investigations of atmospheric humidity variations of both diurnal and seasonal scale. The humidity device measurements will have a lag, when a step-wise change in humidity is taking place. This lag effect is increasing with decreasing temperature, and it is of the order of a few hours at the temperature of -75 °C. To compensate for the lag effect we used an algorithm developed by Mäkinen [2]. The humidity observations were validated after tedious efforts. This was needed to compensate for the artifacts of the transducer electronics. The compensation process includes an assumption that the relative humidity at Mars in the temperature range of 0 to -30 °C is about zero. The

  18. An Abrupt Change in the African Monsoon at the end of the Younger Dryas?

    NASA Astrophysics Data System (ADS)

    Talbot, M. R.; Filippi, M. L.; Jensen, N. B.; Tiercelin, J.

    2005-12-01

    A variety of proxy palaeoclimatic records from tropical Africa and the adjacent oceans suggest that a climatic event equivalent to the Younger Dryas (YD) also affected this region. To date however, little attention has been directed towards the end of the YD in Africa, even though it has been identified as a period of particularly rapid and profound climatic change in the circum-North Atlantic region. High-resolution studies of variations in the elemental and stable carbon- and nitrogen-isotope composition of organic matter in cores from Lakes Malawi, Tanganyika and Bosumtwi (tropical Africa) indicate an abrupt change in the wind-driven circulation of these lakes that, within the limits of available chronologies, was contemporaneous with the end of the YD in the northern hemisphere. The change was apparently coincident with the transition to humid conditions in the central Sahara, with shifts in surface winds recorded in cores from off the coasts of East and West Africa, and possibly also with the onset of the last phase of ice accumulation on Mt. Kilimanjaro. Together, the evidence suggests an abrupt northward translation of the African monsoon system at ca. 11.5 +/- 0.3 cal. ka BP.

  19. The Struggles over African Languages

    ERIC Educational Resources Information Center

    Maseko, Pam; Vale, Peter

    2016-01-01

    In this interview, African Language expert Pam Maseko speaks of her own background and her first encounter with culture outside of her mother tongue, isiXhosa. A statistical breakdown of South African languages is provided as background. She discusses Western (originally missionary) codification of African languages and suggests that this approach…

  20. Psychological Misdiagnosis of African Americans.

    ERIC Educational Resources Information Center

    Garretson, Deborah J.

    1993-01-01

    Reviews historical and current problems with making accurate psychological diagnoses of African Americans. Suggests that misdiagnosis is strongly related to pathologization of African-American culture itself. Explores diagnostic process, stereotypes of African-American psychopathology, cultural differences in values and life stressors, and…

  1. A Middle-Late Pleistocene lacustrine record of humidity variation at the SE Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Appel, E.; Hu, S.; Goddu, S. R.; Herb, C.

    2013-12-01

    Both the East-Asian summer monsoon (EASM) and Indian summer monsoon (ISM) affect the SE Tibetan Plateau (TP). The fine-grained lacustrine sediments from Heqing basin in NW Yunnan provide an excellent archive for long-term high-resolution paleoclimate studies. We analysed data from a 168 m core that spans the period from 900-30 ka, and performed a catchment study. Carbonate content (CC) and magnetic susceptibility (χ) data show clear 100 kyr eccentricity variations. The carbonate (mean CC 38.7%) stems from weathering of the widely occurring and very weakly magnetic limestones (mostly χ<0) in the catchment. Modern red soils around the basin are carbonate-free and strongly magnetic (χ ~10-5 m3kg-1). Magnetite (Mt) and maghemite (Mgh) mainly control χ, but hematite (Ht) is also present. Superparamagnetic (SP) ultra-fine particles (probably pedogenic) are dominating, evidenced by high xfd (7.5-16.7%), in addition to a larger-sized fraction (likely inherited from bedrocks). Much lower χ values and very low xfd (1.1%) in sediments from a stream entering the basin suggest that SP particles are easily dissolved in surface water. The catchment study delivers some clues for the interpretation of the proxy parameters: (i) During more humid times stronger chemical weathering caused higher CC. Soil material was transported into the lake by surface water and wind; river water led to strong dissolution of SP particles. (ii) During less humid times (less vegetation cover) a relatively higher fraction of soil material was transported by wind and a larger fraction of SP particles was preserved, leading to higher χ values. (iii) Humidity has another impact through low-temperature oxidation (LTO) of Mt that can be semi-quantified by magnetic parameters (ARM/SIRM, S-ratio). LTO will be stronger during more humid times, and as CC increases in such phases we can explain the observed first-order anti-correlation of CC and χ. From FCM cluster analysis and a suitable humidity index

  2. Corrective measures technology for humid sites

    SciTech Connect

    Spalding, B.P.

    1983-01-01

    The corrective measures technology task for humid sites consists of three subtasks. The first subtask has the objective of demonstrating that grout injection into closed burial trenches can achieve the hydrologic isolation of buried wastes. From laboratory testing of seven grout formulations, two promising grouts, 7.6% sodium silicate and 11.7% acrylamide, were selected for field demonstration by injection into 1:10-scale burial trenches. Both grouts effected a several orders of magnitude reduction in the mean hydraulic conductivity of the trench. The trench chemical treatment subtask has the objective of demonstrating the caustic soda injection into a closed trench's backfill and surrounding soil can achieve a fixation of radiostrontium from further ground water contamination. Monitoring of ground waters in and around the treated trench indicate a continued fixation of radiostrontium from further leaching. Soil samples were taken from the trench and found to contain /sup 90/Sr coprecipitated with calcium carbonate. The final subtask has the objective of demonstrating that the detection and treatment of ground water seeps can achieve a significant reduction in radiostrontium contamination of surface water. The utility of measuring /sup 90/Sr in ground water samples by Cerenkov radiation detection was found to be analytically equivalent to but considerably less expensive and time consuming than the standard radiochemical method.

  3. Relative humidities in mid-latitude contrails

    NASA Astrophysics Data System (ADS)

    Krämer, M.; Kübbeler, M.; Meyer, J.; Schiller, C.; Gayet, J.-F.; Fiebig, M.; Hamburger, Th.; Petzold, A. Minikin (4), A.; Schlager, H.; Voigt, Ch.

    2009-04-01

    Aircraft contrails frequently occur in the upper troposphere. They consist of ice particles having the potential to directly affect the Earth's climate. The frequency, life time, ice crystal size spectra and thus radiative properties of contrails depend strongly on the ambient distribution of the relative humidity with respect to ice (RHi). In air with RHi below 100% contrails are believed to be short-lived, while persistent contrails require an ambient RHi of at least 100% (Gao et al., 2006, Atmospheric Environment). During the mid-latitude aircraft experiments CONCERT 2008 (CONtrail and Cirrus ExpeRimenT, 6 flights), CIRRUS 2006 (1 flight) and PAZI 2003 ('PArtikel und ZIrren', 2 flights), RHi inside of contrails were measured using the high precision Fast In-situ Stratospheric lyman-alpha Hygrometer FISH. We present results from about 1 hour of observation time in 52 contrails during the 9 flights. The peak of the RHi frequency distribution is around 90%, i.e. most of the contrails are observed in subsaturated air. There is indication that the age of the contrails is much larger than expected, implying that, to date, the lifetime of contrails below 100% RHi is underestimated. Further analysis of the observations is needed to confirm/explain these results.

  4. Temperature and relative humidity distributions in a medium-size administrative town in southwest Nigeria.

    PubMed

    Akinbode, O M; Eludoyin, A O; Fashae, O A

    2008-04-01

    This study was carried out in one of the medium-sized public administrative towns in the southwestern part of Nigeria. Its aim is to highlight the effect of spatial distribution of settlements, population, and socio-economic activities on urban air temperature and humidity in the town. Temperature and relative humidity data from 1992 to 2001 were obtained from three meteorological stations in Akure, the Administrative Capital of Ondo State, Nigeria. The stations are located within the Federal Ministry of Aviation, Akure Airport (FMA), Federal University of Technology, Akure (FUTA) and Federal School of Agriculture (SOA). Air temperature and relative humidity measurements were also obtained from 27 points, which were cited to include road junctions, markets, built up areas, etc., using sling psychrometer. The data were subsequently analysed for spatial and temporal variations using statistical packages (SPSS and Microsoft Excel) and isolines. Actual vapour pressure and dew point temperature were computed using Magnus conversion formulae. The results obtained showed that spatial variation was insignificant, in terms of the temperature and humidity variables. The annual mean temperature (Tmean) ranged between 21.9 and 30.4 degrees C while minimum (Tmin) and maximum (Tmax) temperatures varied from 13 to 26 and 21.5-39.6 degrees C, respectively. Relative humidity (RH), actual vapour pressure (Es) and dew point temperature (Td) values also varied from 39.1% to 98.2%, 19.7-20.8 gm(-3), and 17.3-17.8 degrees C, respectively. A significant relationship (p>0.6; r<0.05) between Tmin, Es and Td was observed while the daytime 'urban heat island' intensity (UHI) ranged between 0.5 and 2.5 degrees C within the study period. The study concluded that there is influence of urban canopy on the microclimate of Akure, and hypothesizes that the urban dwellers may be subjected to some levels of weather related physiological disorderliness. PMID:17482750

  5. Narcolepsy in African Americans

    PubMed Central

    Kawai, Makoto; O'Hara, Ruth; Einen, Mali; Lin, Ling; Mignot, Emmanuel

    2015-01-01

    Study Objectives: Although narcolepsy affects 0.02–0.05% of individuals in various ethnic groups, clinical presentation in different ethnicities has never been fully characterized. Our goal was to study phenotypic expression across ethnicities in the United States. Design/Setting: Cases of narcolepsy from 1992 to 2013 were identified from searches of the Stanford Center for Narcolepsy Research database. International Classification of Sleep Disorders, Third Edition diagnosis criteria for type 1 and type 2 narcolepsy were used for inclusion, but subjects were separated as with and without cataplexy for the purpose of data presentation. Information extracted included demographics, ethnicity and clinical data, HLA-DQB1*06:02, polysomnography (PSG), multiple sleep latency test (MSLT) data, and cerebrospinal fluid (CSF) hypocretin-1 level. Patients: 182 African-Americans, 839 Caucasians, 35 Asians, and 41 Latinos with narcolepsy. Results: Sex ratio, PSG, and MSLT findings did not differ across ethnicities. Epworth Sleepiness Scale (ESS) score was higher and age of onset of sleepiness earlier in African Americans compared with other ethnicities. HLA-DQB1*06:02 positivity was higher in African Americans (91.0%) versus others (76.6% in Caucasians, 80.0% in Asians, and 65.0% in Latinos). CSF hypocretin-1 level, obtained in 222 patients, was more frequently low (≤ 110 pg/ml) in African Americans (93.9%) versus Caucasians (61.5%), Asians (85.7%) and Latinos (75.0%). In subjects with low CSF hypocretin-1, African Americans (28.3%) were 4.5 fold more likely to be without cataplexy when compared with Caucasians (8.1%). Conclusions: Narcolepsy in African Americans is characterized by earlier symptom onset, higher Epworth Sleepiness Scale score, higher HLA-DQB1*06:02 positivity, and low cerebrospinal fluid hypocretin-1 level in the absence of cataplexy. In African Americans, more subjects without cataplexy have type 1 narcolepsy. Citation: Kawai M, O'Hara R, Einen M, Lin L

  6. Africans and the myth of rural retirement in South Africa, ca 1900-1950.

    PubMed

    MacKinnon, Aran S

    2008-06-01

    The South African mining industry relied upon a massive African migrant workforce from the rural areas. Rural transformations in this migrant labor system form an important part of the story of developing capitalism in industrializing South Africa. Yet, recent historical studies on southern African migrant and rural wage labor have paid little attention to life adjustments made by the elderly and those 'burned out' by the mines and forced to leave formal wage employment in the urban areas. The South African segregationist state's rhetoric implied that 'retired' Africans could find economic security in their designated rural reserves. Indeed, legislation sought to prohibit Africans who were not employed from remaining in the 'white' urban areas. By the 1930s, however, the reserves were rapidly deteriorating. Many elderly Africans could not retire and were forced to seek wage labor. This raises significant questions about how retirement came to be defined and experienced by Africans in South Africa during a critical period of dramatic economic decline in the 1930s and 40s, and what the underlying material circumstances of African South Africans were with regard to adaptations to employment and ageing-related life changes. In many cases, elderly Africans were forced to forgo retirement, and find wage labor, usually in the most poorly paid, least sought-after or dangerous fields of employment. This article thus seeks to illuminate critical generational dimensions of the impact of segregation and racism in South Africa prior to the formal articulation of Apartheid. PMID:17939024

  7. Periodized wavelets

    SciTech Connect

    Schlossnagle, G.; Restrepo, J.M.; Leaf, G.K.

    1993-12-01

    The properties of periodized Daubechies wavelets on [0,1] are detailed and contrasted against their counterparts which form a basis for L{sup 2}(R). Numerical examples illustrate the analytical estimates for convergence and demonstrate by comparison with Fourier spectral methods the superiority of wavelet projection methods for approximations. The analytical solution to inner products of periodized wavelets and their derivatives, which are known as connection coefficients, is presented, and several tabulated values are included.

  8. Survival of Phytophthora ramorum hyphae after exposure to temperature extremes and various humidities.

    PubMed

    Browning, Marsha; Englander, Larry; Tooley, Paul W; Berner, Dana

    2008-01-01

    We examined the effect of short-term exposure to high and low temperatures and a range of relative humidity (RH) on survival of Phytophthora ramorum hyphae. Spore-free hyphal colonies were grown on dialysis squares atop V8 medium. Colonies were transferred to water agar plates positioned at 27.5-50 C on a thermal gradient plate and incubated 2.5-480 min. For low temperature trials colonies were transferred to vials of distilled water and incubated in a water bath at -5 to -25 C for 1-24 h. In the relative humidity trials hyphal colonies were transferred to sealed humidity chambers containing various concentrations of glycerin for 1-8 h. Relative humidity was 41-93% at 20 C and 43-86% at 28 C. Survival in all trials was characterized by growth from dialysis squares into V8 medium. Temperatures of 37.5-40 C were lethal to P. ramorum hyphae within several hours, and temperatures of 42.5-50 C were lethal within minutes. Exposure to 32.5 and 35 C resulted in reduced survival over 8 h, while 30 C had no effect on three of four isolates. Hyphal colonies demonstrated considerable tolerance to cold, with all isolates surviving a 24 h exposure to -5 C. Survival diminished over time at lower temperatures, however a few colonies survived 24 h exposure to -25 C. Temperature also affected the ability of hyphal colonies to withstand reduced humidity. A RH of 41-43% was lethal in 2 h at 28 C compared to 8 h at 20 C. Three of four isolates were unaffected by an 8 h exposure to 81 and 95% RH at 20 C, and 73 and 86% RH at 28 C. Isolate differences were apparent in tolerance to freezing temperatures and reduced humidity. From these results it is apparent that the cold temperatures found in the northeastern USA are not likely to prevent the establishment of P. ramorum. There is also the potential for hyphae, and presumably spores, to survive periods of high humidity on the leaf surface in the absence of free water. PMID:18592898

  9. The Genetic Structure and History of Africans and African Americans

    PubMed Central

    Tishkoff, Sarah A.; Reed, Floyd A.; Friedlaender, Françoise R.; Ehret, Christopher; Ranciaro, Alessia; Froment, Alain; Hirbo, Jibril B.; Awomoyi, Agnes A.; Bodo, Jean-Marie; Doumbo, Ogobara; Ibrahim, Muntaser; Juma, Abdalla T.; Kotze, Maritha J.; Lema, Godfrey; Moore, Jason H.; Mortensen, Holly; Nyambo, Thomas B.; Omar, Sabah A.; Powell, Kweli; Pretorius, Gideon S.; Smith, Michael W.; Thera, Mahamadou A.; Wambebe, Charles; Weber, James L.; Williams, Scott M.

    2010-01-01

    Africa is the source of all modern humans, but characterization of genetic variation and of relationships among populations across the continent has been enigmatic. We studied 121 African populations, four African American populations, and 60 non-African populations for patterns of variation at 1327 nuclear microsatellite and insertion/deletion markers. We identified 14 ancestral population clusters in Africa that correlate with self-described ethnicity and shared cultural and/or linguistic properties. We observed high levels of mixed ancestry in most populations, reflecting historical migration events across the continent. Our data also provide evidence for shared ancestry among geographically diverse hunter-gatherer populations (Khoesan speakers and Pygmies). The ancestry of African Americans is predominantly from Niger-Kordofanian (~71%), European (~13%), and other African (~8%) populations, although admixture levels varied considerably among individuals. This study helps tease apart the complex evolutionary history of Africans and African Americans, aiding both anthropological and genetic epidemiologic studies. PMID:19407144

  10. Dynamics of the temperature-humidity index in the Mediterranean basin

    NASA Astrophysics Data System (ADS)

    Segnalini, Maria; Nardone, Alessandro; Bernabucci, Umberto; Vitali, Andrea; Ronchi, Bruno; Lacetera, Nicola

    2011-03-01

    The study was aimed at describing the temperature humidity index (THI) dynamics over the Mediterranean basin for the period 1951-2007. The THI combines temperature and humidity into a single value, and may help to predict the effects of environmental warmth in farm animals. In particular, on the basis of THI values, numerous studies have been performed to establish thresholds for heat stress in dairy cows. The THI was calculated by using monthly mean values of temperature and humidity obtained from the National Center for Environmental Prediction/National Center for Atmospheric Research reanalysis project. The analysis demonstrated a high degree of heterogeneity of THI patterns over the Mediterranean basin, a strong north-south gradient, and an overall warming during the study period, which was particularly marked during summer seasons. Results indicated that several areas of the basin present summer THI values which were unfavorable to cow welfare and productivity, and that risk of heat stress for cows is generally greater in the countries of the south coast of the basin. Furthermore, THI data from the summer 2003 revealed that severe positive anomalies may impact areas normally characterized by a favorable climate for animal production. In conclusion, THI dynamics should be taken into careful consideration by farmers and policy makers operating in Mediterranean countries when planning investments in the sector of animal production. The investments should at least partially be directed towards implementation of adaptation measures, which may help to alleviate the impact of hot on farm animals welfare, performance and health.

  11. Geoindicators for river and river-valley monitoring in the humid tropics

    USGS Publications Warehouse

    Osterkamp, W.R.

    2002-01-01

    Geoindicators for rivers and river valleys in the humid tropics are suggested to indicate environmental change during periods of up to a century. Geoindicators suggested for upland areas of supply are rainfall-runoff relations, rates of soil movement and slope failure, and analyses of drainage density. Data applicable to sediment storage in lowlands are rates of sediment deposition as shown by monuments, short-lived radioisotopes, and pollen. Discharges of water, sediment, and dissolved solids are basic geoindicators for large streams, especially when analyses include flood frequency, stage-discharge relations, flow duration, sediment-rating curves, and comparisons of dissolved loads to sediment loads. The utility of geoindicators in the humid tropics may be greatest if observation sites are selected with a network design to permit comparisons of sites with similar conditions of climate and drainage-basin characteristics.

  12. Average Tropical Relative Humidity from AIRS, Dec-Feb 2002-2005

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The average tropospheric relative humidity from AIRS for the four December-February periods during 2002 through 2005.

    The Atmospheric Infrared Sounder Experiment, with its visible, infrared, and microwave detectors, provides a three-dimensional look at Earth's weather. Working in tandem, the three instruments can make simultaneous observations all the way down to the Earth's surface, even in the presence of heavy clouds. With more than 2,000 channels sensing different regions of the atmosphere, the system creates a global, 3-D map of atmospheric temperature and humidity and provides information on clouds, greenhouse gases, and many other atmospheric phenomena. The AIRS Infrared Sounder Experiment flies onboard NASA's Aqua spacecraft and is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., under contract to NASA. JPL is a division of the California Institute of Technology in Pasadena.

  13. Stability of freeze-dried tablets at different relative humidities.

    PubMed

    Corveleyn, S; Remon, J P

    1999-09-01

    The purpose of the study was to evaluate the stability of two different freeze-dried tablet formulations at different relative humidities (RHs). The tablets contained 25 mg hydrochlorothiazide (HCT) as a model drug and were prepared by freeze-drying a suspension and an oil-in-water (o/w) emulsion. Formulation A was a rapidly disintegrating tablet and consisted of 80 mg of maltodextrine DE38; 8 mg of polyethyleneglycol (PEG 6000), 8 mg of xanthan gum, and 25 mg of HCT. Formulation B was a lyophilized dry emulsion tablet that consisted of 160 mg of Miglyol 812, 80 mg of maltodextrin DE38, 16 mg of methylcellulose (Methocel) A15LV, and 25 mg of HCT. Tablets were packaged in different packing materials: polyvinylchloride (PVC)/aluminum blister packs, PVC-polyvinylidenechloride (PVDC)/aluminum blister packs, closed containers with a dessicant tablet, and open containers. The tablets were stored at three relative humidities (45%, 60%, and 85% RH) and were characterized on mechanical strength, residual moisture, porosity, content uniformity, and scanning electron microscopy (SEM) during a period of 6 months. After 1 month at 60% and 85% RH, a strong increase in moisture content (from 2.7% to 6.8%) was seen for the tablets packed in the open and closed containers and for the PVC/aluminum blistered tablets. This increase was higher for formulation A compared to formulation B since B contained 160 mg of triglycerides and was more hydrophobic. This increase in water content was correlated with a decrease in mechanical strength. The tablets also showed a change in microstructure and porosity. At a moisture content of 7.2%, formulation A showed a structural "collapse" since water acts as a plasticizer for the amorphous glass, lowering the glass transition temperature Tg. This phenomenon even occurred in PVC/aluminum blister packs at 85% RH. The structural collapse was associated with a complete loss of microstructure as detected by porosimetric analysis and SEM. For the PVC

  14. The Other African Americans.

    ERIC Educational Resources Information Center

    Matory, J. Lorand

    Black North America is ethnically and culturally diverse. It contains many groups who do not call themselves or have not always called themselves "Negro,""Black,""African-American," and so forth, such as Louisiana Creoles of color and many of the Indian tribes east of the Mississippi. There are also numerous North American ethnic groups of African…

  15. African American rhinoplasty.

    PubMed

    Boyette, Jennings R; Stucker, Fred J

    2014-08-01

    Rhinoplasty in patients of African descent requires a patient-specific approach, because the goals and ideal proportions differ from the white nose. This article discusses approaches to surgical correction of common anatomic variations. In addition, common pitfalls are outlined. PMID:25049123

  16. Elective: African Literature.

    ERIC Educational Resources Information Center

    Jenkins, Kenneth V.

    The make-up of a course in African literature for high school students is discussed. It is pointed out that the course can be constructed on already familiar lines. High school students will be able to describe clearly, for example, the relationship between environment and character or the dilemma of characters caught between traditional values…

  17. East African megadroughts between 135 and 75 thousand years ago and bearing on early-modern human origins

    PubMed Central

    Scholz, Christopher A.; Johnson, Thomas C.; Cohen, Andrew S.; King, John W.; Peck, John A.; Overpeck, Jonathan T.; Talbot, Michael R.; Brown, Erik T.; Kalindekafe, Leonard; Amoako, Philip Y. O.; Lyons, Robert P.; Shanahan, Timothy M.; Castañeda, Isla S.; Heil, Clifford W.; Forman, Steven L.; McHargue, Lanny R.; Beuning, Kristina R.; Gomez, Jeanette; Pierson, James

    2007-01-01

    The environmental backdrop to the evolution and spread of early Homo sapiens in East Africa is known mainly from isolated outcrops and distant marine sediment cores. Here we present results from new scientific drill cores from Lake Malawi, the first long and continuous, high-fidelity records of tropical climate change from the continent itself. Our record shows periods of severe aridity between 135 and 75 thousand years (kyr) ago, when the lake's water volume was reduced by at least 95%. Surprisingly, these intervals of pronounced tropical African aridity in the early late-Pleistocene were much more severe than the Last Glacial Maximum (LGM), the period previously recognized as one of the most arid of the Quaternary. From these cores and from records from Lakes Tanganyika (East Africa) and Bosumtwi (West Africa), we document a major rise in water levels and a shift to more humid conditions over much of tropical Africa after ≈70 kyr ago. This transition to wetter, more stable conditions coincides with diminished orbital eccentricity, and a reduction in precession-dominated climatic extremes. The observed climate mode switch to decreased environmental variability is consistent with terrestrial and marine records from in and around tropical Africa, but our records provide evidence for dramatically wetter conditions after 70 kyr ago. Such climate change may have stimulated the expansion and migrations of early modern human populations. PMID:17785420

  18. Is Obsidian Hydration Dating Affected by Relative Humidity?

    USGS Publications Warehouse

    Friedman, I.; Trembour, F.W.; Smith, G.I.; Smith, F.L.

    1994-01-01

    Experiments carried out under temperatures and relative humidities that approximate ambient conditions show that the rate of hydration of obsidian is a function of the relative humidity, as well as of previously established variables of temperature and obsidian chemical composition. Measurements of the relative humidity of soil at 25 sites and at depths of between 0.01 and 2 m below ground show that in most soil environments, at depths below about 0.25 m, the relative humidity is constant at 100%. We have found that the thickness of the hydrated layer developed on obsidian outcrops exposed to the sun and to relative humidities of 30-90% is similar to that formed on other portions of the outcrop that were shielded from the sun and exposed to a relative humidity of approximately 100%. Surface samples of obsidian exposed to solar heating should hydrate more rapidly than samples buried in the ground. However, the effect of the lower mean relative humidity experiences by surface samples tends to compensate for the elevated temperature, which may explain why obsidian hydration ages of surface samples usually approximate those derived from buried samples.

  19. Characterization of a Sulfonated Polycarbonate Resistive Humidity Sensor

    PubMed Central

    Rubinger, Carla P.L.; Calado, Hallen D.R.; Rubinger, Rero M.; Oliveira, Henrique; Donnici, Claudio L.

    2013-01-01

    In this work; resistive moisture sensors were obtained by dip coating sulfonated polycarbonate (SPC) onto silver interdigitated electrodes. Commercial polycarbonate was sulfonated with acetyl sulphate at two different sulfonation degrees corresponding to 9.0 and 18.0 mole %. Impedance spectroscopy was used to investigate the humidity sensing properties at controlled relative humidity (RH%) environments generated from standard saline solutions in the range of 11–90 RH%. For the highest sulfonated sample; in the RH% range investigated (11 to 90%); the sensor impedance changed from 4.7 MΩ to 18 kΩ. Humidity sensors made from sulfonated polycarbonate showed exponential decay behavior of the impedance at constant frequency with the environmental relative humidity. Sample 9SPC presented dielectric relaxation response for environmental humidity between 58 and 90 RH% while sample 18SPC presented dielectric relaxation response for the entire measured range between 11 and 90 RH%. Sulfonated polycarbonate could be a promising material for the fabrication of simple and cheap humidity-sensing sensors for the assessment of relative humidity of the surrounding environment, as suggested by experimental results. PMID:23385415

  20. Mars Science Laboratory relative humidity observations: Initial results

    PubMed Central

    Harri, A-M; Genzer, M; Kemppinen, O; Gomez-Elvira, J; Haberle, R; Polkko, J; Savijärvi, H; Rennó, N; Rodriguez-Manfredi, JA; Schmidt, W; Richardson, M; Siili, T; Paton, M; Torre-Juarez, M De La; Mäkinen, T; Newman, C; Rafkin, S; Mischna, M; Merikallio, S; Haukka, H; Martin-Torres, J; Komu, M; Zorzano, M-P; Peinado, V; Vazquez, L; Urqui, R

    2014-01-01

    The Mars Science Laboratory (MSL) made a successful landing at Gale crater early August 2012. MSL has an environmental instrument package called the Rover Environmental Monitoring Station (REMS) as a part of its scientific payload. REMS comprises instrumentation for the observation of atmospheric pressure, temperature of the air, ground temperature, wind speed and direction, relative humidity (REMS-H), and UV measurements. We concentrate on describing the REMS-H measurement performance and initial observations during the first 100 MSL sols as well as constraining the REMS-H results by comparing them with earlier observations and modeling results. The REMS-H device is based on polymeric capacitive humidity sensors developed by Vaisala Inc., and it makes use of transducer electronics section placed in the vicinity of the three humidity sensor heads. The humidity device is mounted on the REMS boom providing ventilation with the ambient atmosphere through a filter protecting the device from airborne dust. The final relative humidity results appear to be convincing and are aligned with earlier indirect observations of the total atmospheric precipitable water content. The water mixing ratio in the atmospheric surface layer appears to vary between 30 and 75 ppm. When assuming uniform mixing, the precipitable water content of the atmosphere is ranging from a few to six precipitable micrometers. Key Points Atmospheric water mixing ratio at Gale crater varies from 30 to 140 ppm MSL relative humidity observation provides good data Highest detected relative humidity reading during first MSL 100 sols is RH75% PMID:26213667

  1. A climatology of tropospheric humidity inversions in five reanalyses

    NASA Astrophysics Data System (ADS)

    Brunke, Michael A.; Stegall, Steve T.; Zeng, Xubin

    2015-02-01

    Specific humidity is generally thought to decrease with height in the troposphere. However, here we document the existence of specific humidity inversions in five reanalyses: the National Centers for Environmental Prediction (NCEP) second reanalysis (NCEP-2), the European Centre for Medium-Range Forecasts (ECMWF) 40-year reanalysis (ERA-40), the Modern Era Retrospective Analysis for Research Applications (MERRA), NCEP's Climate Forecast System Reanalysis (CFSR), and the ECMWF interim reanalysis (ERA-Interim). These inversions are most frequent in the polar regions. Inversions do occur elsewhere, most notably over the subtropical stratus regions, but are less frequent and likely overproduced depending on the location. Polar inversions are the most persistent in winter and the strongest (as defined by the humidity difference divided by the pressure difference across the inversion) in summer or autumn with low bases (at pressures > 900 hPa). Winter humidity inversions are lower, being near-surface, due to the persistence of low-level temperature inversions associated with these humidity inversions, while summer humidity inversions tend to be located near cloud top providing moisture to prevent the melt season stratus from evaporating. The most important contributions to affect humidity inversions in MERRA are dynamics, turbulence, and moist physics. However, local advection may not play as much of a role as regional humidity convergence. The subtropical stratus inversions are as thick as polar humidity inversions but with higher bases generally at pressures < 900 hPa. These inversions are confirmed by rawinsonde data, but there are discrepancies between the observed annual and diurnal cycles in inversion frequency and those portrayed in the reanalyses.

  2. Compensating for Effects of Humidity on Electronic Noses

    NASA Technical Reports Server (NTRS)

    Homer, Margie; Ryan, Margaret A.; Manatt, Kenneth; Zhou, Hanying; Manfreda, Allison

    2004-01-01

    A method of compensating for the effects of humidity on the readouts of electronic noses has been devised and tested. The method is especially appropriate for use in environments in which humidity is not or cannot be controlled for example, in the vicinity of a chemical spill, which can be accompanied by large local changes in humidity. Heretofore, it has been common practice to treat water vapor as merely another analyte, the concentration of which is determined, along with that of the other analytes, in a computational process based on deconvolution. This practice works well, but leaves room for improvement: changes in humidity can give rise to large changes in electronic-nose responses. If corrections for humidity are not made, the large humidity-induced responses may swamp smaller responses associated with low concentrations of analytes. The present method offers an improvement. The underlying concept is simple: One augments an electronic nose with a separate humidity and a separate temperature sensor. The outputs of the humidity and temperature sensors are used to generate values that are subtracted from the readings of the other sensors in an electronic nose to correct for the temperature-dependent contributions of humidity to those readings. Hence, in principle, what remains after corrections are the contributions of the analytes only. Laboratory experiments on a first-generation electronic nose have shown that this method is effective and improves the success rate of identification of analyte/ water mixtures. Work on a second-generation device was in progress at the time of reporting the information for this article.

  3. A Decrease in Temperature and Humidity Precedes Human Rhinovirus Infections in a Cold Climate.

    PubMed

    Ikäheimo, Tiina M; Jaakkola, Kari; Jokelainen, Jari; Saukkoriipi, Annika; Roivainen, Merja; Juvonen, Raija; Vainio, Olli; Jaakkola, Jouni J K

    2016-01-01

    Both temperature and humidity may independently or jointly contribute to the risk of human rhinovirus (HRV) infections, either through altered survival and spread of viruses in the environment or due to changes in host susceptibility. This study examined the relationship between short-term variations in temperature and humidity and the risk of HRV infections in a subarctic climate. We conducted a case-crossover study among conscripts (n = 892) seeking medical attention due to respiratory symptoms during their military training and identified 147 HRV cases by real-time PCR. An average temperature, a decline in daily ambient temperature and absolute humidity (AH) during the three preceding days of the onset (hazard period) and two reference periods (a week prior and after the onset) were obtained. The average daily temperature preceding HRV infections was -9.9 ± 4.9 °C and the average AH was 2.2 ± 0.9 g/m³. An average (odds ratios (OR) 1.07 (95% confidence interval (CI) 1.00-1.15)) and maximal (OR 1.08 (1.01-1.17)) change in temperature increased the risk of HRV infections by 8% per 1 °C decrease. An average (OR 1.20 (CI 1.03-1.40)) and maximal decrease (OR 1.13 (CI 0.96-1.34)) in AH increased the risk of HRV infection by 13% and 20% per 0.5 g/m³ decrease. A higher average temperature during the three preceding days was positively associated with HRV infections (OR 1.07 (CI 1.00-1.15)). A decrease rather than low temperature and humidity per se during the preceding few days increases the risk of HRV infections in a cold climate. The information is applicable to populations residing in cold climates for appropriate personal protection and prevention of adverse health effects. PMID:27598190

  4. Periodic cages.

    PubMed

    Diudea, Mircea V; Nagy, Csaba L; Silaghi-Dumitrescu, Ioan; Graovac, Ante; Janezic, Dusanka; Vikić-Topić, Drazen

    2005-01-01

    Various cages are constructed by using three types of caps: f-cap (derived from spherical fullerenes by deleting zones of various size), kf-cap (obtainable by cutting off the polar ring, of size k), and t-cap ("tubercule"-cap). Building ways are presented, some of them being possible isomerization routes in the real chemistry of fullerenes. Periodic cages with ((5,7)3) covering are modeled, and their constitutive typing enumeration is given. Spectral data revealed some electronic periodicity in fullerene clusters. Semiempirical and strain energy calculations complete their characterization. PMID:15807490

  5. Four-year long-path monitoring of ambient aerosol extinction at a central European urban site: dependence on relative humidity

    NASA Astrophysics Data System (ADS)

    Skupin, A.; Ansmann, A.; Engelmann, R.; Seifert, P.; Müller, T.

    2016-02-01

    The ambient aerosol particle extinction coefficient is measured with the Spectral Aerosol Extinction Monitoring System (SÆMS) along a 2.84 km horizontal path at 30-50 m height above ground in the urban environment of Leipzig (51.3° N, 12.4° E), Germany, since 2009. The dependence of the particle extinction coefficient (wavelength range from 300 to 1000 nm) on relative humidity up to almost 100 % was investigated. The main results are presented. For the wavelength of 550 nm, the mean extinction enhancement factor was found to be 1.75 ± 0.4 for an increase of relative humidity from 40 to 80 %. The respective 4-year mean extinction enhancement factor is 2.8 ± 0.6 for a relative-humidity increase from 40 to 95 %. A parameterization of the dependency of the urban particle extinction coefficient on relative humidity is presented. A mean hygroscopic exponent of 0.46 for the 2009-2012 period was determined. Based on a backward trajectory cluster analysis, the dependence of several aerosol optical properties for eight air flow regimes was investigated. Large differences were not found, indicating that local pollution sources widely control the aerosol conditions over the urban site. The comparison of the SÆMS extinction coefficient statistics with respective statistics from ambient AERONET sun photometer observations yields good agreement. Also, time series of the particle extinction coefficient computed from in situ-measured dry particle size distributions and humidity-corrected SÆMS extinction values (for 40 % relative humidity) were found in good overall consistency, which verifies the applicability of the developed humidity parameterization scheme. The analysis of the spectral dependence of particle extinction (Ångström exponent) revealed an increase of the 390-881 nm Ångström exponent from, on average, 0.3 (at 30 % relative humidity) to 1.3 (at 95 % relative humidity) for the 4-year period.

  6. Passive microwave relative humidity retrievals using feedforward neural networks

    SciTech Connect

    Cabrera-Mercader, C.R.; Staelin, D.H.

    1995-11-01

    A technique for retrieving atmospheric humidity profiles using passive microwave spectral observations from satellite and Multilayer Feedforward Neural Networks (MFNN) is introduced in this paper. Relative humidity retrievals on a global scale from simulated radiances at fifteen frequencies between 23.8 and 183.3 GHz yielded rms errors in relative humidity of 6--14% over ocean and 6--15% over land at pressure levels ranging from 131 mbar to 1,013 mbar. Comparison with a combined statistical and physical iterative retrieval scheme shows that superior retrievals can be obtained at a lower computational cost using MFNN.

  7. Relative humidity: important modifier of pollutant uptake by plants

    SciTech Connect

    McLaughlin, S.B.; Taylor, G.E.

    1981-01-09

    Laboratory measurements of foliar uptake of sulfur dioxide and ozone by red kidney beans demonstrated a strong effect of relative humidity on internal pollutant dose. Foliar uptake was enhanced two- to threefold for sulfur dioxide and three- to fourfold for ozone by an increase in relative humidity from 35 to 75 percent. For the same exposure concentration, vegetation growing in humid areas (such as the eastern United States) may experience a significantly greater internal flux of pollutants than that in more arid regions. 22 references, 1 figure, 1 table.

  8. The impact of temperature errors on perceived humidity supersaturation

    NASA Astrophysics Data System (ADS)

    Buehler, S. A.; Courcoux, N.

    2003-07-01

    A Monte Carlo method is used to study the propagation of temperature uncertainties into relative humidity with respect to ice (RH i ) calculated from specific humidity. For a flat specific humidity distribution and Gaussian temperature uncertainties the resulting RH i distribution drops exponentially at high RH i values-much slower than a Gaussian. This agrees well with the RH i distribution measured by the Microwave Limb Sounder (MLS), which means that such remotely measured RH i distributions can be explained, at least partly, by temperature uncertainties.

  9. Humidity sensing property of polyaniline - cromium oxide nanocomposites

    NASA Astrophysics Data System (ADS)

    Sajjan, K. C.; Faisal, Muhammad; Vijaya Kumari, S. C.; Ravikiran, Y. T.; Khasim, Syed

    2013-06-01

    New type of conducting polyamine-cromium oxide (PANI-Cr2O3) nanocomposites have been synthesized by in situ deposition technique by placing fine grade powder of cromium Oxide during in situ polymerization of aniline. The composites formed were characterized by Scanning Electron Microscopy (SEM). The SEM image confirmed uniform distribution of Cr2O3 particles in the PAni matrix. The humidity sensing mechanism of the PAni-Cr2O3 composites was studied and change in resistance with relative humidity(RH) ranging from 20% to 95% were recorded. It was found that Cr2O3 after making composite with PANI, exhibits good humidity sensing property.

  10. Nacre-mimetic clay/xyloglucan bionanocomposites: a chemical modification route for hygromechanical performance at high humidity.

    PubMed

    Kochumalayil, Joby J; Morimune, Seira; Nishino, Takashi; Ikkala, Olli; Walther, Andreas; Berglund, Lars A

    2013-11-11

    Nacre-mimetic bionanocomposites of high montmorillonite (MTM) clay content, prepared from hydrocolloidal suspensions, suffer from reduced strength and stiffness at high relative humidity. We address this problem by chemical modification of xyloglucan in (XG)/MTM nacre-mimetic nanocomposites, by subjecting the XG to regioselective periodate oxidation of side chains to enable it to form covalent cross-links to hydroxyl groups in neighboring XG chains or to the MTM surface. The resulting materials are analyzed by FTIR spectroscopy, thermogravimetric analysis, carbohydrate analysis, calorimetry, X-ray diffraction, scanning electron microscopy, tensile tests, and oxygen barrier properties. We compare the resulting mechanical properties at low and high relative humidity. The periodate oxidation leads to a strong increase in modulus and strength of the materials. A modulus of 30 GPa for cross-linked composite at 50% relative humidity compared with 13.7 GPa for neat XG/MTM demonstrates that periodate oxidation of the XG side chains leads to crucially improved stress transfer at the XG/MTM interface, possibly through covalent bond formation. This enhanced interfacial adhesion and internal cross-linking of the matrix moreover preserves the mechanical properties at high humidity condition and leads to a Young's modulus of 21 GPa at 90%RH. PMID:24083456

  11. The Rise of Nationalism: Freedom Regained. Through African Eyes: Cultures in Change, Unit V.

    ERIC Educational Resources Information Center

    Clark, Leon E., Ed.

    The exciting period after World War II, when independence movements developed and flourished throughout Africa is the topic of this book, fifth in a series dealing with African culture and intended for secondary level students. Almost all of the selections in the book were written by Africans and come from a variety of sources including…

  12. "Ebony Jr.!": The Rise and Demise of an African American Children's Magazine

    ERIC Educational Resources Information Center

    Henderson, Laretta

    2006-01-01

    "Ebony Jr.!" was a very popular periodical magazine that targeted an audience of African American children from five to eleven-years-old, as it combined all the elements of popular culture, African-American history and an elementary school curriculum for them. With the passage of time, it became a relatively irrelevant and bland magazine, leaving…

  13. African-American Materials Project Experiment in Regional Cooperation. Final Report.

    ERIC Educational Resources Information Center

    Hall, Carol J.

    The African-American Materials Project was a three year venture in bibliographic control of African-American materials. It was a regional project, designed to locate and describe materials in six Southern states. The project was divided into three periods. Phase I was devoted to locating existing collections through the use of a questionnaire,…

  14. African American Students' Graphic Understanding of the Derivative: Critical Case Studies

    ERIC Educational Resources Information Center

    Stringer, Eddy W., III.

    2011-01-01

    Data suggests that a significant loss of African American students from STEM majors occur between their freshmen and sophomore year. This attrition corresponds to the time period when students encounter the calculus sequence. For this reason, calculus persists as a serious barrier preventing African American students from entering STEM fields.…

  15. African Ancestry Is Associated with Asthma Risk in African Americans

    PubMed Central

    Pino-Yanes, María; Wade, Michael S.; Pérez-Méndez, Lina; Kittles, Rick A.; Wang, Deli; Papaiahgari, Srinivas; Ford, Jean G.; Kumar, Rajesh; Garcia, Joe G. N.

    2012-01-01

    Background Asthma is a common complex condition with clear racial and ethnic differences in both prevalence and severity. Asthma consultation rates, mortality, and severe symptoms are greatly increased in African descent populations of developed countries. African ancestry has been associated with asthma, total serum IgE and lower pulmonary function in African-admixed populations. To replicate previous findings, here we aimed to examine whether African ancestry was associated with asthma susceptibility in African Americans. In addition, we examined for the first time whether African ancestry was associated with asthma exacerbations. Methodology/Principal Findings After filtering for self-reported ancestry and genotype data quality, samples from 1,117 self-reported African-American individuals from New York and Baltimore (394 cases, 481 controls), and Chicago (321 cases followed for asthma exacerbations) were analyzed. Genetic ancestry was estimated based on ancestry informative markers (AIMs) selected for being highly divergent among European and West African populations (95 AIMs for New York and Baltimore, and 66 independent AIMs for Chicago). Among case-control samples, the mean African ancestry was significantly higher in asthmatics than in non-asthmatics (82.0±14.0% vs. 77.8±18.1%, mean difference 4.2% [95% confidence interval (CI):2.0–6.4], p<0.0001). This association remained significant after adjusting for potential confounders (odds ratio: 4.55, 95% CI: 1.69–12.29, p = 0.003). African ancestry failed to show an association with asthma exacerbations (p = 0.965) using a model based on longitudinal data of the number of exacerbations followed over 1.5 years. Conclusions/Significance These data replicate previous findings indicating that African ancestry constitutes a risk factor for asthma and suggest that elevated asthma rates in African Americans can be partially attributed to African genetic ancestry. PMID:22235241

  16. The relationship between indoor and outdoor temperature, apparent temperature, relative humidity, and absolute humidity

    PubMed Central

    Nguyen, Jennifer L.; Schwartz, Joel; Dockery, Douglas W.

    2013-01-01

    Introduction Many studies report an association between outdoor ambient weather and health. Outdoor conditions may be a poor indicator of personal exposure because people spend most of their time indoors. Few studies have examined how indoor conditions relate to outdoor ambient weather. Methods and Results The average indoor temperature, apparent temperature, relative humidity (RH), and absolute humidity (AH) measured in 16 homes in Greater Boston, Massachusetts, from May 2011 - April 2012 was compared to measurements taken at Boston Logan airport. The relationship between indoor and outdoor temperatures is non-linear. At warmer outdoor temperatures, there is a strong correlation between indoor and outdoor temperature (Pearson correlation coefficient, r = 0.91, slope, β = 0.41), but at cooler temperatures, the association is weak (r = 0.40, β = 0.04). Results were similar for outdoor apparent temperature. The relationships were linear for RH and AH. The correlation for RH was modest (r = 0.55, β = 0.39). AH exhibited the strongest indoor-to-outdoor correlation (r = 0.96, β = 0.69). Conclusions Indoor and outdoor temperatures correlate well only at warmer outdoor temperatures. Outdoor RH is a poor indicator of indoor RH, while indoor AH has a strong correlation with outdoor AH year-round. PMID:23710826

  17. HUMID AIR TURBINE CYCLE TECHNOLOGY DEVELOPMENT PROGRAM

    SciTech Connect

    Richard Tuthill

    2002-07-18

    The Humid Air Turbine (HAT) Cycle Technology Development Program focused on obtaining HAT cycle combustor technology that will be the foundation of future products. The work carried out under the auspices of the HAT Program built on the extensive low emissions stationary gas turbine work performed in the past by Pratt & Whitney (P&W). This Program is an integral part of technology base development within the Advanced Turbine Systems Program at the Department of Energy (DOE) and its experiments stretched over 5 years. The goal of the project was to fill in technological data gaps in the development of the HAT cycle and identify a combustor configuration that would efficiently burn high moisture, high-pressure gaseous fuels with low emissions. The major emphasis will be on the development of kinetic data, computer modeling, and evaluations of combustor configurations. The Program commenced during the 4th Quarter of 1996 and closed in the 4th Quarter of 2001. It teamed the National Energy Technology Laboratory (NETL) with P&W, the United Technologies Research Center (UTRC), and a subcontractor on-site at UTRC, kraftWork Systems Inc. The execution of the program started with bench-top experiments that were conducted at UTRC for extending kinetic mechanisms to HAT cycle temperature, pressure, and moisture conditions. The fundamental data generated in the bench-top experiments was incorporated into the analytical tools available at P&W to design the fuel injectors and combustors. The NETL then used the hardware to conduct combustion rig experiments to evaluate the performance of the combustion systems at elevated pressure and temperature conditions representative of the HAT cycle. The results were integrated into systems analysis done by kraftWork to verify that sufficient understanding of the technology had been achieved and that large-scale technological application and demonstration could be undertaken as follow-on activity. An optional program extended the

  18. Circadian activity of Culicoides oxystoma (Diptera: Ceratopogonidae), potential vector of bluetongue and African horse sickness viruses in the Niayes area, Senegal.

    PubMed

    Fall, Moussa; Fall, Assane G; Seck, Momar T; Bouyer, Jérémy; Diarra, Maryam; Balenghien, Thomas; Garros, Claire; Bakhoum, Mame T; Faye, Ousmane; Baldet, Thierry; Gimonneau, Geoffrey

    2015-08-01

    Culicoides biting midges (Diptera: Ceratopogonidae) are important vectors of arboviruses in Africa. Culicoides oxystoma has been recently recorded in the Niayes region of Senegal (West Africa) and its high abundance on horses suggests a potential implication in the transmission of the African horse sickness virus in this region. This species is also suspected to transmit bluetongue virus to imported breeds of sheep. Little information is available on the biology and ecology of Culicoides in Africa. Therefore, understanding the circadian host-seeking activity of this putative vector is of primary importance to assess the risk of the transmission of Culicoides-borne pathogens. To achieve this objective, midges were collected using a sheep-baited trap over two consecutive 24-h periods during four seasons in 2012. A total of 441 Culicoides, belonging to nine species including 418 (94.8%) specimens of C. oxystoma, were collected. C. oxystoma presented a bimodal circadian host-seeking activity at sunrise and sunset in July and was active 3 h after sunrise in April. Daily activity appeared mainly related to time periods. Morning activity increased with the increasing temperature up to about 27 °C and then decreased with the decreasing humidity, suggesting thermal limits for C. oxystoma activity. Evening activity increased with the increasing humidity and the decreasing temperature, comprised between 20 and 27 °C according to seasons. Interestingly, males were more abundant in our sampling sessions, with similar activity periods than females, suggesting potential animal host implication in the facilitation of reproduction. Finally, the low number of C. oxystoma collected render practical vector-control recommendations difficult to provide and highlight the lack of knowledge on the bio-ecology of this species of veterinary interest. PMID:26002826

  19. Long-period humidity variability in the Arctic atmosphere from upper-air observations

    NASA Astrophysics Data System (ADS)

    Agurenko, A.; Khokhlova, A.

    2014-12-01

    Under climate change, atmospheric water content also tends to change. This gives rise to changes in the amount of moisture transferred, clouds and precipitation, as well as in hydrological regime. This work analyzes seasonal climatic characteristics of precipitated water in the Arctic atmosphere, by using 1972-2011 data from 55 upper-air stations located north of 60°N. Regions of maximum and minimum mean values and variability trends are determined. In the summer, water amount is shown to increase in nearly the whole of the latitudinal zone. The comparison with the similar characteristics of reanalysis obtained by the other authors shows a good agreement. Time variation in the atmosphere moisture transport crossing 70°N, which is calculated from observation data, is presented and compared with model results. The work is supported by the joint EC ERA.Net RUS and Russian Fundamental Research Fund Project "Arctic Climate Processes Linked Through the Circulation of the Atmosphere" (ACPCA) (project 12-05-91656-ЭРА_а).

  20. Influence of environmental humidity on plasma etching polyamide 6 films

    NASA Astrophysics Data System (ADS)

    Gao, Zhiqiang

    2012-05-01

    The environmental humidity (EH) may have potential influence on atmospheric pressure plasma treatment. In order to investigate how the environmental humidity affects atmospheric pressure plasma treatment, polyamide 6 (PA 6) films were treated by helium/oxygen (He/O2) plasmas using atmospheric pressure plasma jet (APPJ) at different environmental humidity. The plasma treated samples had lower contact angles than the control. Atomic force microscopy (AFM) showed increased surface roughness, while X-ray photoelectron spectroscopy (XPS) revealed increased oxygen contents after the plasma treatments. The plasma treated films had higher T-peel strength than that of the control as revealed by T-peel strength tests. It was shown that the addition of environmental humidity increased effectiveness of the plasma in polymer surface modification after the treatment.

  1. Hydration-dehydration, heat, humidity, and "cool, clear, water".

    PubMed

    Lockett, Lawrence J

    2012-12-01

    Personal recollections of dehydration meltdowns during the Kona Ironman Triathlon, reflections on their cause, and the author's experiential recommendations regarding hydration, prevention of dehydration, and "beat the heat and humidity" measures. PMID:23147099

  2. An investigation of thermal comfort at high humidities

    SciTech Connect

    Fountain, M.E.; Arens, E. Xu, T.; Bauman, F.S.; Oguru, Masayuki

    1999-07-01

    Climate chamber experiments were performed to investigate thermal comfort at high humidities. Subjective reports were recorded for a total of 411 subjects at frequent intervals during the three-hour experiments with 65 selected subjects equipped with instrumentation to record skin wettedness and skin temperature. The exposures ranged from 20 C/60% RH to 26 C/90% RH with two clothing levels, 0.5 and 0.9 clo, and three levels of metabolic activity, 1.2, 1.6, and 4 met. Clear differences in humidity response were not found for sedentary subjects; however, non-sedentary activities produced differences on several subjective scales. These differences, though, are dictated via heat balance and thermoregulation and cannot be separated from humidity-related effects. For metabolic rates 1.6 met and above, these data suggest that no practical limit on humidity will lower the percent dissatisfied below 25%.

  3. Radiation Dry Bias of the Vaisala RS92 Humidity Sensor

    NASA Technical Reports Server (NTRS)

    Vomel, H.; Selkirk, H.; Miloshevich, L.; Valverde-Canossa, J.; Valdes, J.; Kyro, E.; Kivi, R.; Stolz, W.; Peng, G.; Diaz, J. A.

    2007-01-01

    The comparison of simultaneous humidity measurements by the Vaisala RS92 radiosonde and by the Cryogenic Frostpoint Hygrometer (CFH) launched at Alajuela, Cosla Rica, during July 2005 reveals a large solar radiation dry bias of the Vaisala RS92 humidity sensor and a minor temperature-dependent calibration error. For soundings launched at solar zenith angles between 10" and 30 , the average dry bias is on the order of 9% at the surface and increases to 50% at 15 km. A simple pressure- and temperature-dependent correction based on the comparison with the CFH can reduce this error to less than 7% at all altitudes up to 15.2 km, which is 700 m below the tropical tropopause. The correction does not depend on relative humidity, but is able to reproduce the relative humidity distribution observed by the CFH.

  4. Laboratory Connections: Gas Monitoring Transducers: Relative Humidity Sensors.

    ERIC Educational Resources Information Center

    Powers, Michael H.; Hull, Stacey E.

    1988-01-01

    Explains the operation of five relative humidity sensors: psychrometer, hair hygrometer, resistance hygrometer, capacitance hygrometer, and resistance-capacitance hygrometer. Outlines the theory behind the electronic sensors and gives computer interfacing information. Lists sensor responses for calibration. (MVL)

  5. Hydrology and Water Management in the Humid Tropics

    NASA Astrophysics Data System (ADS)

    Bonell, Michael; Hufschmidt, Maynard M.; Gladwell, John S.

    1993-09-01

    This book considers all aspects of hydrology in the humid tropics. The first four parts of the book cover the physical basis of hydrology in the humid tropics: climatology, meteorology, process hydrology, sedimentation, water quality and freshwater ecology. This is followed by extensive treatment of the human and societal issues: land-use changes, water resource management, and rural and urban water supply in the tropical regions.

  6. Humidity sensors printed on recycled paper and cardboard.

    PubMed

    Mraović, Matija; Muck, Tadeja; Pivar, Matej; Trontelj, Janez; Pleteršek, Anton

    2014-01-01

    Research, design, fabrication and results of various screen printed capacitive humidity sensors is presented in this paper. Two types of capacitive humidity sensors have been designed and fabricated via screen printing on recycled paper and cardboard, obtained from the regional paper and cardboard industry. As printing ink, commercially available silver nanoparticle-based conductive ink was used. A considerable amount of work has been devoted to the humidity measurement methods using paper as a dielectric material. Performances of different structures have been tested in a humidity chamber. Relative humidity in the chamber was varied in the range of 35%-80% relative humidity (RH) at a constant temperature of 23 °C. Parameters of interest were capacitance and conductance of each sensor material, as well as long term behaviour. Process reversibility has also been considered. The results obtained show a mainly logarithmic response of the paper sensors, with the only exception being cardboard-based sensors. Recycled paper-based sensors exhibit a change in value of three orders of magnitude, whereas cardboard-based sensors have a change in value of few 10s over the entire scope of relative humidity range (RH 35%-90%). Two different types of capacitor sensors have been investigated: lateral (comb) type sensors and modified, perforated flat plate type sensors. The objective of the present work was to identify the most important factors affecting the material performances with humidity, and to contribute to the development of a sensor system supported with a Radio Frequency Identification (RFID) chip directly on the material, for use in smart packaging applications. Therefore, the authors built a passive and a battery-supported wireless module based on SL900A smart sensory tag's IC to achieve UHF-RFID functionality with data logging capability. PMID:25072347

  7. Enhancement of humidity sensitivity of graphene through functionalization with polyethylenimine

    SciTech Connect

    Ben Aziza, Zeineb; Baillargeat, Dominique

    2015-09-28

    In this work, we show that the sensing performance of graphene based humidity sensors can be largely improved through polymer functionalization. Chemical vapor deposited graphene is functionalized with amine rich polymer, leading to electron transfer from amine groups in the polymer to graphene. The functionalized graphene humidity sensor has demonstrated good sensitivity, recovery, and repeatability. Charge transfer between the functionalized graphene and water molecules and the sensing mechanism are studied systemically using field effect transistor geometry and scanning Kelvin probe microscopy.

  8. Humidity Sensors Printed on Recycled Paper and Cardboard

    PubMed Central

    Mraović, Matija; Muck, Tadeja; Pivar, Matej; Trontelj, Janez; Pleteršek, Anton

    2014-01-01

    Research, design, fabrication and results of various screen printed capacitive humidity sensors is presented in this paper. Two types of capacitive humidity sensors have been designed and fabricated via screen printing on recycled paper and cardboard, obtained from the regional paper and cardboard industry. As printing ink, commercially available silver nanoparticle-based conductive ink was used. A considerable amount of work has been devoted to the humidity measurement methods using paper as a dielectric material. Performances of different structures have been tested in a humidity chamber. Relative humidity in the chamber was varied in the range of 35%–80% relative humidity (RH) at a constant temperature of 23 °C. Parameters of interest were capacitance and conductance of each sensor material, as well as long term behaviour. Process reversibility has also been considered. The results obtained show a mainly logarithmic response of the paper sensors, with the only exception being cardboard-based sensors. Recycled paper-based sensors exhibit a change in value of three orders of magnitude, whereas cardboard-based sensors have a change in value of few 10s over the entire scope of relative humidity range (RH 35%–90%). Two different types of capacitor sensors have been investigated: lateral (comb) type sensors and modified, perforated flat plate type sensors. The objective of the present work was to identify the most important factors affecting the material performances with humidity, and to contribute to the development of a sensor system supported with a Radio Frequency Identification (RFID) chip directly on the material, for use in smart packaging applications. Therefore, the authors built a passive and a battery-supported wireless module based on SL900A smart sensory tag's IC to achieve UHF-RFID functionality with data logging capability. PMID:25072347

  9. Periodic Polymers

    NASA Astrophysics Data System (ADS)

    Thomas, Edwin

    2013-03-01

    Periodic polymers can be made by self assembly, directed self assembly and by photolithography. Such materials provide a versatile platform for 1, 2 and 3D periodic nano-micro scale composites with either dielectric or impedance contrast or both, and these can serve for example, as photonic and or phononic crystals for electromagnetic and elastic waves as well as mechanical frames/trusses. Compared to electromagnetic waves, elastic waves are both less complex (longitudinal modes in fluids) and more complex (longitudinal, transverse in-plane and transverse out-of-plane modes in solids). Engineering of the dispersion relation between wave frequency w and wave vector, k enables the opening of band gaps in the density of modes and detailed shaping of w(k). Band gaps can be opened by Bragg scattering, anti-crossing of bands and discrete shape resonances. Current interest is in our group focuses using design - modeling, fabrication and measurement of polymer-based periodic materials for applications as tunable optics and control of phonon flow. Several examples will be described including the design of structures for multispectral band gaps for elastic waves to alter the phonon density of states, the creation of block polymer and bicontinuous metal-carbon nanoframes for structures that are robust against ballistic projectiles and quasi-crystalline solid/fluid structures that can steer shock waves.

  10. Cause-of-Death Disparities in the African Diaspora: Exploring Differences Among Shared-Heritage Populations

    PubMed Central

    Jeyaseelan, Selvi; Howitt, Christina; Sobers-Grannum, Natasha; Hennis, Anselm J.; Wilks, Rainford J.; Harris, E. Nigel; MacLeish, Marlene; Sullivan, Louis W.

    2015-01-01

    Objectives. We investigated changes in life expectancy (LE) and cause-specific mortality over time, directly comparing African-descent populations in the United States and the Caribbean. Methods. We compared LE at birth and cause-specific mortality in 6 disease groups between Caribbean countries with a majority (> 90%) African-descent population and US African Americans. Results. The LE improvement among African Americans exceeded that of Afro-Caribbeans so that the LE gap, which favored the Caribbean population by 1.5 years in 1990, had been reversed by 2009. This relative improvement among African Americans was mainly the result of the improving mortality experience of African American men. Between 2000 and 2009, Caribbean mortality rates in 5 of the 6 disease groups increased relative to those of African Americans. By 2009, mortality from cerebrovascular diseases, cancers, and diabetes was higher in Afro-Caribbeans relative to African Americans, with a diabetes mortality rate twice that of African Americans and 4 times that of White Americans. Conclusions. The Caribbean community made important mortality reductions between 2000 and 2009, but this progress fell short of African American health improvements in the same period, especially among men. PMID:25905849

  11. Variability of summer humidity during the past 800 years on the eastern Tibetan Plateau inferred from δ18O of tree-ring cellulose

    NASA Astrophysics Data System (ADS)

    Wernicke, J.; Grießinger, J.; Hochreuther, P.; Bräuning, A.

    2015-02-01

    We present an 800-year δ18O chronology from the eastern part of the Tibetan Plateau (TP). The chronology dates back to AD 1193 and was sampled in AD 1996 from living Juniperus tibetica trees. This first long-term tree-ring-based δ18O chronology for eastern Tibet provides a reliable archive for hydroclimatic reconstructions. Highly significant correlations were obtained with hydroclimatic variables (relative humidity, vapour pressure, and precipitation) during the summer season. We applied a linear transfer model to reconstruct summer season relative humidity variations over the past 800 years. More moist conditions prevailed during the termination of the Medieval Warm Period while a systematic shift during the Little Ice Age is not detectable. A distinct trend towards more dry conditions since the 1870s is apparent. The moisture decline weakened around the 1950s but still shows a negative trend. The mid-19th century humidity decrease is in good accordance with several multiproxy hydroclimate reconstructions for south Tibet. However, the pronounced summer relative humidity decline is stronger on the central and eastern TP. Furthermore, the relative humidity at our study site is significantly linked to the relative humidity at large parts of the TP. Therefore, we deduce that the reconstructed relative humidity is mostly controlled by local and mesoscale climatic drivers, although significant connections to the higher troposphere of west-central Asia were observed.

  12. Variability of summer humidity during the past 800 years on the eastern Tibetan Plateau inferred from δ18O of tree-ring cellulose

    NASA Astrophysics Data System (ADS)

    Wernicke, J.; Grießinger, J.; Hochreuther, P.; Bräuning, A.

    2014-08-01

    We present an 800 years long δ18O chronology from the eastern part of the Tibetan Plateau (TP). The chronology dates back to 1193 AD and was sampled in 1996 AD from living Juniperus tibetica trees. The chronology is unique for eastern Tibet and provides a reliable archive for hydroclimatic reconstructions. Highly significant correlations were obtained with air moisture (relative humidity, vapour pressure and precipitation) during the summer season. We applied a linear transfer model to reconstruct the summer season relative humidity variation over the past 800 years. We identified more moist conditions at the termination of the Medieval Warm Period, an oscillating air humidity around the mean during the Little Ice Age and a sudden decrease of relative humidity since the 1870s. The late 19th century humidity decrease is in good accordance with several multiproxy hydroclimate reconstructions for south Tibet. On the other hand, since the end of the 19th century strong evidences for an increase in humidity on the northern TP is exhibited. Spatial correlation analysis with the North Atlantic Oscillation index (NAO) and the sea surface temperature (SST) of Niño region 3.4 reveal a weak and nonstationary relationship to the δ18O chronology. Instead, spatial correlations expose a dominating convective influence to the relative humidity reconstruction. Furthermore, wavelength analysis reveal good agreements between the significant cyclicities in our δ18O chronology and several moisture sensitive proxy archives.

  13. A CMOS Smart Temperature and Humidity Sensor with Combined Readout

    PubMed Central

    Eder, Clemens; Valente, Virgilio; Donaldson, Nick; Demosthenous, Andreas

    2014-01-01

    A fully-integrated complementary metal-oxide semiconductor (CMOS) sensor for combined temperature and humidity measurements is presented. The main purpose of the device is to monitor the hermeticity of micro-packages for implanted integrated circuits and to ensure their safe operation by monitoring the operating temperature and humidity on-chip. The smart sensor has two modes of operation, in which either the temperature or humidity is converted into a digital code representing a frequency ratio between two oscillators. This ratio is determined by the ratios of the timing capacitances and bias currents in both oscillators. The reference oscillator is biased by a current whose temperature dependency is complementary to the proportional to absolute temperature (PTAT) current. For the temperature measurement, this results in an exceptional normalized sensitivity of about 0.77%/°C at the accepted expense of reduced linearity. The humidity sensor is a capacitor, whose value varies linearly with relative humidity (RH) with a normalized sensitivity of 0.055%/% RH. For comparison, two versions of the humidity sensor with an area of either 0.2 mm2 or 1.2 mm2 were fabricated in a commercial 0.18 μm CMOS process. The on-chip readout electronics operate from a 5 V power supply and consume a current of approximately 85 μA. PMID:25230305

  14. Air motion determination by tracking humidity patterns in isentropic layers

    NASA Technical Reports Server (NTRS)

    Mancuso, R. L.; Hall, D. J.

    1975-01-01

    Determining air motions by tracking humidity patterns in isentropic layers was investigated. Upper-air rawinsonde data from the NSSL network and from the AVE-II pilot experiment were used to simulate temperature and humidity profile data that will eventually be available from geosynchronous satellites. Polynomial surfaces that move with time were fitted to the mixing-ratio values of the different isentropic layers. The velocity components of the polynomial surfaces are part of the coefficients that are determined in order to give an optimum fitting of the data. In the mid-troposphere, the derived humidity motions were in good agreement with the winds measured by rawinsondes so long as there were few or no clouds and the lapse rate was relatively stable. In the lower troposphere, the humidity motions were unreliable primarily because of nonadiabatic processes and unstable lapse rates. In the upper troposphere, the humidity amounts were too low to be measured with sufficient accuracy to give reliable results. However, it appears that humidity motions could be used to provide mid-tropospheric wind data over large regions of the globe.

  15. A CMOS smart temperature and humidity sensor with combined readout.

    PubMed

    Eder, Clemens; Valente, Virgilio; Donaldson, Nick; Demosthenous, Andreas

    2014-01-01

    A fully-integrated complementary metal-oxide semiconductor (CMOS) sensor for combined temperature and humidity measurements is presented. The main purpose of the device is to monitor the hermeticity of micro-packages for implanted integrated circuits and to ensure their safe operation by monitoring the operating temperature and humidity on-chip. The smart sensor has two modes of operation, in which either the temperature or humidity is converted into a digital code representing a frequency ratio between two oscillators. This ratio is determined by the ratios of the timing capacitances and bias currents in both oscillators. The reference oscillator is biased by a current whose temperature dependency is complementary to the proportional to absolute temperature (PTAT) current. For the temperature measurement, this results in an exceptional normalized sensitivity of about 0.77%/°C at the accepted expense of reduced linearity. The humidity sensor is a capacitor, whose value varies linearly with relative humidity (RH) with a normalized sensitivity of 0.055%/% RH. For comparison, two versions of the humidity sensor with an area of either 0.2 mm2 or 1.2 mm2 were fabricated in a commercial 0.18 μm CMOS process. The on-chip readout electronics operate from a 5 V power supply and consume a current of approximately 85 µA. PMID:25230305

  16. Characteristics of dielectric barrier discharge plasmas in atmospheric humid air

    NASA Astrophysics Data System (ADS)

    Fukuda, Y.; Fukui, K.; Iwami, R.; Matsuoka, Y.; Kikuchi, Y.; Fukumoto, N.; Nagata, M.

    2012-10-01

    Atmospheric pressure plasmas have a great advantage for industrial applications such as surface modifications, sterilization and film preparation. In particular, reactive plasmas including OH radicals can be generated in humid air. On the other hand, it is known that dielectric barrier discharge (DBD) plasmas in air are strongly affected by humidity. In this study, a twisted pair sample is used as a DBD electrode. The twisted pair consists of two enameled wires, and it is installed in a climate chamber to control ambient temperature and humidity. Repetitive impulse voltage pulses were applied to the twisted pair to produce DBD plasmas. Light emission, electromagnetic wave and current pulses were used to detect discharge activities. The discharge inception voltage (DIV) is basically determined by Paschen curve in air, however, the DIV was decreased by increasing the humidity. In addition, it was found that there were largely scattered data of DIV at the low humidity condition. After the pre-discharges, the DIV reached to the steady state value. On the other hand, there was no scattering of the observed DIV at the high humidity condition. Measurements of surface potential of the sample after the discharge show these behaviors could be explained by surface charge accumulation on the enameled wire. It is noted that there was no fluctuation in the DIV data in the case of unipolar voltage pulse.

  17. Effect of humidity on aerosolization of micronized drugs.

    PubMed

    Young, Paul M; Price, Robert; Tobyn, Michael J; Buttrum, Mark; Dey, Fiona

    2003-10-01

    The variation of aerosolization with humidity for three micronized drugs used in the treatment of asthma was evaluated by using in vitro methods. Micronized samples of disodium cromoglycate (DSCG), salbutamol sulphate, and triamcinolone acetonide (TAA) were stored for 12hr at 15, 30, 45, 60, and 75% relative humidity (RH). A suitable "reservoir" dry powder inhaler was loaded and tested by using a twin-stage impinger at each specific humidity. The aerosolization efficiency of all three micronized drugs was affected by variations in humidity. The percentage of the delivered dose and the fine particle fraction of the loaded dose (FPFLD) for both DSCG and salbutamol sulphate decreased with increasing humidity; with the largest decrease in FPFLD occurring between 45% and 60% RH for DSCG and 60% to 75% RH for salbutamol sulphate. These observations suggest that the adhesion properties for both DSCG and salbutamol sulphate, which govern the aerosolization efficiency, are predominately influenced by capillary interactions. In contrast, the FPFLD for TAA significantly increased as the humidity increased over the range 15% to 75% RH, suggesting that triboelectric forces predominate particle-particle interactions. These variations in drug particulate behavior highlight the importance of an individual formulation approach when developing dry powder inhalation systems. PMID:14606660

  18. Humidity effects on calibrations of radiation therapy electrometers

    SciTech Connect

    Downton, B.; Walker, S.

    2012-02-15

    Purpose: To eliminate variation in electrometer calibration results caused by high humidity and suboptimal connectors on the standard capacitors and to implement hardware that prevents overloading of the input stage of electrometers during calibration. Methods: A humidity-controlled cabinet was installed to provide a low-humidity environment for the standard capacitors. All of the coaxial BNC connections were replaced with Triax (TRB) connectors with the exception of the output from the voltage source. A three-stage RC filter with cascaded RC low-pass sections was designed and tested. Results: The installation of the humidity cabinet resulted in a major improvement in the stability and reproducibility of the electrometer calibration system. For the three years since this upgrade, the Ionizing Radiation Standards (IRS) electrometer calibration results have been consistent regardless of the ambient relative humidity in the lab. The connector replacements improved grounding in the calibration circuit. The three-stage filter allows the voltage at the output to rise in an S-shaped waveform, resulting in a smooth rise of the current through the isolation resistor from zero and back again, with no abrupt transition. For the filter design chosen, 99.99% of the charge is delivered within 6 s. Conclusions: A three-way improvement to the calibration measurement system was successful in eliminating the observed variations, resulting in an electrometer calibration measurement system that is unaffected by humidity and allowing reliable year-round calibrations of any electrometer encountered since the implementation of these changes.

  19. Variations of relative humidity in relation to meningitis in Africa

    NASA Astrophysics Data System (ADS)

    Seefeldt, M. W.; Hopson, T. M.

    2011-12-01

    The meningitis belt is a region covering Sub-Saharan Africa from the Sahel of West Africa eastward to western Ethiopia. The region is prone to meningitis epidemics during the dry season extending from approximately January to May, depending on the region. Relative humidity has been found to be a critical environmental factor indicating the susceptibility of a region to meningitis epidemics. This study evaluates the variation of relative humidity across West Africa over 30 dry-seasons (1979 - 2009) using the NASA-MERRA dataset. The method of self-organizing maps is employed to characterize the changes in relative humidity patterns across the region within a given dry season as well as changes over the 30 years. A general pattern of changes in relative humidity is indicated as the rainbelt retreats to the south at the onset of the dry season and then returns to the region at the end of the dry season. Within each dry season there is a unique pattern. The climatological conditions of relative humidity at the onset of the dry season provide an indication of the moisture environment for the entire dry season. Year to year variation in the relative humidity patterns are found to be gradual. Future applications involve using the results from the SOM evaluation to be used for future decisions involving prevention of meningitis epidemics.

  20. Understanding traditional African healing

    PubMed Central

    MOKGOBI, M.G.

    2015-01-01

    Traditional African healing has been in existence for many centuries yet many people still seem not to understand how it relates to God and religion/spirituality. Some people seem to believe that traditional healers worship the ancestors and not God. It is therefore the aim of this paper to clarify this relationship by discussing a chain of communication between the worshipers and the Almighty God. Other aspects of traditional healing namely types of traditional healers, training of traditional healers as well as the role of traditional healers in their communities are discussed. In conclusion, the services of traditional healers go far beyond the uses of herbs for physical illnesses. Traditional healers serve many roles which include but not limited to custodians of the traditional African religion and customs, educators about culture, counselors, social workers and psychologists. PMID:26594664

  1. Electro-Hydrodynamics and Kinetic Modeling of Dry and Humid Air Flows Activated by Corona Discharges

    NASA Astrophysics Data System (ADS)

    P. Sarrette, J.; Eichwald, O.; Marchal, F.; Ducasse, O.; Yousfi, M.

    2016-05-01

    The present work is devoted to the 2D simulation of a point-to-plane Atmospheric Corona Discharge Reactor (ACDR) powered by a DC high voltage supply. The corona reactor is periodically crossed by thin mono filamentary streamers with a natural repetition frequency of some tens of kHz. The study compares the results obtained in dry air and in air mixed with a small amount of water vapour (humid air). The simulation involves the electro-dynamics, chemical kinetics and neutral gas hydrodynamics phenomena that influence the kinetics of the chemical species transformation. Each discharge lasts about one hundred of a nanosecond while the post-discharge occurring between two successive discharges lasts one hundred of a microsecond. The ACDR is crossed by a lateral dry or humid air flow initially polluted with 400 ppm of NO. After 5 ms, the time corresponding to the occurrence of 50 successive discharge/post-discharge phases, a higher NO removal rate and a lower ozone production rate are found in humid air. This change is due to the presence of the HO2 species formed from the H primary radical in the discharge zone.

  2. Effect of humidity on lung surfactant films subjected to dynamic compression/expansion cycles.

    PubMed

    Acosta, Edgar J; Gitiafroz, Roya; Zuo, Yi Y; Policova, Zdenka; Cox, Peter N; Hair, Michael L; Neumann, A Wilhelm

    2007-03-15

    The surface activity of bovine lipid extracted surfactant (BLES) preparations used in surfactant replacement therapy is studied in dynamic film compression/expansion cycles as a function of relative humidity, surfactant concentration, compression rate, and compression periodicity. BLES droplets were formed in a constrained sessile droplet configuration (CSD). Images obtained during cycling were analyzed using axisymmetric drop shape analysis (ADSA) to yield surface tension, surface area, and drop volume data. The experiments were conducted in a chamber that allowed both humid (100% RH), and "dry" air (i.e. less than 20% RH) environments. It was observed that in humid environments BLES films are not stable and tend to have poor surface activity compared to BLES films exposed to dry air. Further analysis of the data reveal that if BLES films are compressed fast enough (i.e. at physiological conditions) to avoid film hydration, lower minimum surface tensions are achieved. A film hydration-relaxation mechanism is proposed to explain these observations. PMID:16877051

  3. African horse sickness.

    PubMed

    Zientara, S; Weyer, C T; Lecollinet, S

    2015-08-01

    African horse sickness (AHS) is a devastating disease of equids caused by an arthropod-borne virus belonging to the Reoviridae family, genus Orbivirus. It is considered a major health threat for horses in endemic areas in sub-Saharan Africa. African horse sickness virus (AHSV) repeatedly caused large epizootics in the Mediterranean region (North Africa and southern Europe in particular) as a result of trade in infected equids. The unexpected emergence of a closely related virus, the bluetongue virus, in northern Europe in 2006 has raised fears about AHSV introduction into Europe, and more specifically into AHSV-free regions that have reported the presence of AHSV vectors, e.g. Culicoides midges. North African and European countries should be prepared to face AHSV incursions in the future, especially since two AHSV serotypes (serotypes 2 and 7) have recently spread northwards to western (e.g. Senegal, Nigeria, Gambia) and eastern Africa (Ethiopia), where historically only serotype 9 had been isolated. The authors review key elements of AHS epidemiology, surveillance and prophylaxis. PMID:26601437

  4. Advancing breast cancer survivorship among African-American women.

    PubMed

    Coughlin, Steven S; Yoo, Wonsuk; Whitehead, Mary S; Smith, Selina A

    2015-09-01

    Advances have occurred in breast cancer survivorship but, for many African-American women, challenges and gaps in relevant information remain. This article identifies opportunities to address disparities in breast cancer survival and quality of life, and thereby to increase breast cancer survivorship among African-American women. For breast cancer survivors, common side effects, lasting for long periods after cancer treatment, include fatigue, loss of strength, difficulty sleeping, and sexual dysfunction. For addressing physical and mental health concerns, a variety of interventions have been evaluated, including exercise and weight training, dietary interventions, yoga and mindfulness-based stress reduction, and support groups or group therapy. Obesity has been associated with breast cancer recurrence and poorer survival. Relative to white survivors, African-American breast cancer survivors are more likely to be obese and less likely to engage in physical activity, although exercise improves overall quality of life and cancer-related fatigue. Considerable information exists about the effectiveness of such interventions for alleviating distress and improving quality of life among breast cancer survivors, but few studies have focused specifically on African-American women with a breast cancer diagnosis. Studies have identified a number of personal factors that are associated with resilience, increased quality of life, and positive adaptation to a breast cancer diagnosis. There is a need for a better understanding of breast cancer survivorship among African-American women. Additional evaluations of interventions for improving the quality of life and survival of African-American breast cancer survivors are desirable. PMID:26303657

  5. Soil phosphorus dynamics in a humid tropical silvopastoral system

    SciTech Connect

    Cooperband, L.R.

    1992-01-01

    In developing countries of the humid tropics, timber exploitation and agricultural expansion frequently result in deforestation. Extensive land management, coupled with inherently low soil fertility invariably produce declines in agricultural/livestock productivity which eventually lead to land abandonment and further deforestation. Phosphorus is often the major nutrient limiting plant growth in tropical soils. Agroforestry systems have been considered as viable alternatives to current land use practices. Several hypotheses suggest that combining trees with crops or pasture, especially leguminous species will improve soil nutrient cycling, soil structure and soil organic matter. In this experiment Erythrina berteroana (an arboreous legume) was grown in native grass pastures in Costa Rica to determine the effects of tree pruning and cattle grazing on soil P availability. I measured soil P fluxes as well as changes in pasture biomass over an 18-month period. In a separate field experiment, I determined decomposition rates and P release characteristics of Erythrina leaves, pasture grass clippings and cattle dung. Erythrina leaves decomposed faster than both pasture grass and cattle dung. Erythrina and pasture residues released 4-5 times less P than dung. Phosphorus fluxes after tree pruning and grazing were highly dynamic for all treatments. Tree pruning increased labile soil P over time when coupled with grazing. Pasture biomass production was greatest in the grazed tree treatment. Pasture biomass P production and concentration was greatest in the non-grazed treatment. Trees and grazing together tended to increase nutrient (P) turnover which stimulated biomass production. In contrast, trees without grazing promoted nutrient (P) accumulation in pasture biomass.

  6. East African Rift Valley, Kenya

    NASA Technical Reports Server (NTRS)

    1990-01-01

    This rare, cloud free view of the East African Rift Valley, Kenya (1.5N, 35.5E) shows a clear view of the Turkwell River Valley, an offshoot of the African REift System. The East African Rift is part of a vast plate fracture which extends from southern Turkey, through the Red Sea, East Africa and into Mozambique. Dark green patches of forests are seen along the rift margin and tea plantations occupy the cooler higher ground.

  7. Temperature insensitive hysteresis free highly sensitive polymer optical fiber Bragg grating humidity sensor.

    PubMed

    Woyessa, Getinet; Nielsen, Kristian; Stefani, Alessio; Markos, Christos; Bang, Ole

    2016-01-25

    The effect of humidity on annealing of poly (methyl methacrylate) (PMMA) based microstructured polymer optical fiber Bragg gratings (mPOFBGs) and the resulting humidity responsivity are investigated. Typically annealing of PMMA POFs is done in an oven without humidity control around 80°C and therefore at low humidity. We demonstrate that annealing at high humidity and high temperature improves the performances of mPOFBGs in terms of stability and sensitivity to humidity. PMMA POFBGs that are not annealed or annealed at low humidity level will have a low and highly temperature dependent sensitivity and a high hysteresis in the humidity response, in particular when operated at high temperature. PMMA mPOFBGs annealed at high humidity show higher and more linear humidity sensitivity with negligible hysteresis. We also report how annealing at high humidity can blue-shift the FBG wavelength more than 230 nm without loss in the grating strength. PMID:26832503

  8. Fabrication and Characterization of a CMOS-MEMS Humidity Sensor.

    PubMed

    Dennis, John-Ojur; Ahmed, Abdelaziz-Yousif; Khir, Mohd-Haris

    2015-01-01

    This paper reports on the fabrication and characterization of a Complementary Metal Oxide Semiconductor-Microelectromechanical System (CMOS-MEMS) device with embedded microheater operated at relatively elevated temperatures (40 °C to 80 °C) for the purpose of relative humidity measurement. The sensing principle is based on the change in amplitude of the device due to adsorption or desorption of humidity on the active material layer of titanium dioxide (TiO2) nanoparticles deposited on the moving plate, which results in changes in the mass of the device. The sensor has been designed and fabricated through a standard 0.35 µm CMOS process technology and post-CMOS micromachining technique has been successfully implemented to release the MEMS structures. The sensor is operated in the dynamic mode using electrothermal actuation and the output signal measured using a piezoresistive (PZR) sensor connected in a Wheatstone bridge circuit. The output voltage of the humidity sensor increases from 0.585 mV to 30.580 mV as the humidity increases from 35% RH to 95% RH. The output voltage is found to be linear from 0.585 mV to 3.250 mV as the humidity increased from 35% RH to 60% RH, with sensitivity of 0.107 mV/% RH; and again linear from 3.250 mV to 30.580 mV as the humidity level increases from 60% RH to 95% RH, with higher sensitivity of 0.781 mV/% RH. On the other hand, the sensitivity of the humidity sensor increases linearly from 0.102 mV/% RH to 0.501 mV/% RH with increase in the temperature from 40 °C to 80 °C and a maximum hysteresis of 0.87% RH is found at a relative humidity of 80%. The sensitivity is also frequency dependent, increasing from 0.500 mV/% RH at 2 Hz to reach a maximum value of 1.634 mV/% RH at a frequency of 12 Hz, then decreasing to 1.110 mV/% RH at a frequency of 20 Hz. Finally, the CMOS-MEMS humidity sensor showed comparable response, recovery, and repeatability of measurements in three cycles as compared to a standard sensor that directly

  9. Fabrication and Characterization of a CMOS-MEMS Humidity Sensor

    PubMed Central

    Dennis, John-Ojur; Ahmed, Abdelaziz-Yousif; Khir, Mohd-Haris

    2015-01-01

    This paper reports on the fabrication and characterization of a Complementary Metal Oxide Semiconductor-Microelectromechanical System (CMOS-MEMS) device with embedded microheater operated at relatively elevated temperatures (40 °C to 80 °C) for the purpose of relative humidity measurement. The sensing principle is based on the change in amplitude of the device due to adsorption or desorption of humidity on the active material layer of titanium dioxide (TiO2) nanoparticles deposited on the moving plate, which results in changes in the mass of the device. The sensor has been designed and fabricated through a standard 0.35 µm CMOS process technology and post-CMOS micromachining technique has been successfully implemented to release the MEMS structures. The sensor is operated in the dynamic mode using electrothermal actuation and the output signal measured using a piezoresistive (PZR) sensor connected in a Wheatstone bridge circuit. The output voltage of the humidity sensor increases from 0.585 mV to 30.580 mV as the humidity increases from 35% RH to 95% RH. The output voltage is found to be linear from 0.585 mV to 3.250 mV as the humidity increased from 35% RH to 60% RH, with sensitivity of 0.107 mV/% RH; and again linear from 3.250 mV to 30.580 mV as the humidity level increases from 60% RH to 95% RH, with higher sensitivity of 0.781 mV/% RH. On the other hand, the sensitivity of the humidity sensor increases linearly from 0.102 mV/% RH to 0.501 mV/% RH with increase in the temperature from 40 °C to 80 °C and a maximum hysteresis of 0.87% RH is found at a relative humidity of 80%. The sensitivity is also frequency dependent, increasing from 0.500 mV/% RH at 2 Hz to reach a maximum value of 1.634 mV/% RH at a frequency of 12 Hz, then decreasing to 1.110 mV/% RH at a frequency of 20 Hz. Finally, the CMOS-MEMS humidity sensor showed comparable response, recovery, and repeatability of measurements in three cycles as compared to a standard sensor that directly

  10. Resistive graphene humidity sensors with rapid and direct electrical readout

    NASA Astrophysics Data System (ADS)

    Smith, Anderson D.; Elgammal, Karim; Niklaus, Frank; Delin, Anna; Fischer, Andreas C.; Vaziri, Sam; Forsberg, Fredrik; Råsander, Mikael; Hugosson, Håkan; Bergqvist, Lars; Schröder, Stephan; Kataria, Satender; Östling, Mikael; Lemme, Max C.

    2015-11-01

    We demonstrate humidity sensing using a change of the electrical resistance of single-layer chemical vapor deposited (CVD) graphene that is placed on top of a SiO2 layer on a Si wafer. To investigate the selectivity of the sensor towards the most common constituents in air, its signal response was characterized individually for water vapor (H2O), nitrogen (N2), oxygen (O2), and argon (Ar). In order to assess the humidity sensing effect for a range from 1% relative humidity (RH) to 96% RH, the devices were characterized both in a vacuum chamber and in a humidity chamber at atmospheric pressure. The measured response and recovery times of the graphene humidity sensors are on the order of several hundred milliseconds. Density functional theory simulations are employed to further investigate the sensitivity of the graphene devices towards water vapor. The interaction between the electrostatic dipole moment of the water and the impurity bands in the SiO2 substrate leads to electrostatic doping of the graphene layer. The proposed graphene sensor provides rapid response direct electrical readout and is compatible with back end of the line (BEOL) integration on top of CMOS-based integrated circuits.We demonstrate humidity sensing using a change of the electrical resistance of single-layer chemical vapor deposited (CVD) graphene that is placed on top of a SiO2 layer on a Si wafer. To investigate the selectivity of the sensor towards the most common constituents in air, its signal response was characterized individually for water vapor (H2O), nitrogen (N2), oxygen (O2), and argon (Ar). In order to assess the humidity sensing effect for a range from 1% relative humidity (RH) to 96% RH, the devices were characterized both in a vacuum chamber and in a humidity chamber at atmospheric pressure. The measured response and recovery times of the graphene humidity sensors are on the order of several hundred milliseconds. Density functional theory simulations are employed to further

  11. A monostatic microwave transmission experiment for line integrated precipitation and humidity remote sensing

    NASA Astrophysics Data System (ADS)

    Chwala, Christian; Kunstmann, Harald; Hipp, Susanne; Siart, Uwe

    2014-07-01

    Near-surface water vapor and precipitation are central hydrometeorological observables which are still difficult to quantify accurately above the point scale. Both play an important role in modeling and remote sensing of the hydrologic cycle. We present details on the development of a new microwave transmission experiment that is capable of providing line integrated estimates of both humidity and precipitation near the surface. The system is located at a hydrometeorological test site (TERENO-prealpine) in Southern Germany. Path length is kept short at 660 m to minimize the likelihood of different precipitation types and intensities along the path. It uses a monostatic configuration with a combined transmitter/receiver unit and a 70 cm trihedral reflector. The transmitter/receiver unit simultaneously operates at 22.235 GHz and 34.8 GHz with a pulse repetition rate of 25 kHz and alternating horizontal and vertical polarization, which enable the analysis of the impact of the changing drop size distribution on the rain rate retrieval. Due to the coherence and the high phase stability of the system, it allows for a sensitive observation of the propagation phase delay. Thereof, time series of line integrated refractivity can be determined. This proxy is then post-processed to absolute humidity and compared to station observations. We present the design of the system and show an analysis of selected periods for both, precipitation and humidity observations. The theoretically expected dependence of attenuation and differential attenuation on the DSD was reproduced with experimental data. A decreased performance was observed when using a fixed A-R power law. Humidity data derived from the phase delay measurement showed good agreement with in situ measurements.

  12. Co-effect of increased humidity and meteorological conditions on greenhouse gas fluxes in a young hybrid aspen forest

    NASA Astrophysics Data System (ADS)

    Hansen, Raili; Mander, Ülo; Kupper, Priit; Soosaar, Kaido; Maddison, Martin; Sõber, Jaak; Lõhmus, Krista

    2014-05-01

    Due to the climate change, higher precipitation and an increase in air humidity is expected in northern Europe in the near future (IPCC 2007). There are some studies about irrigation, elevated CO2 and O3 etc., but still we have too little knowledge about the humidity effect on the deciduous forest ecosystem. In 2006 a free-air humidity manipulation (FAHM) facility was established in Estonia and in 2008 we started to artificially increase the air humidity in young hybrid aspen (Populus tremula L. x P. tremuloides Michx.) forest trials on an Endogleyic Planosol of former arable land. Air humidity was raised on average about 7% compared to ambient condition (Tullus et al., 2012). We measured the carbon dioxide, methane and nitrous oxide fluxes from the FAHM system using closed static chamber and gas-chromatograph techniques from July 2009 to November 2012 during snow free periods. Flux measurements were done once a month in three humidification (h) plots and in three control (c) plots. We monitored soil temperature, soil water potential (SWP), precipitation and relative humidity. The vegetation period was rainy in 2009, droughty in 2010 and 2011 (according to SWP the drought was severe in 2011) and cold in 2012. Soil respiration was the lowest in 2011 both in c and h plots; however it was significantly higher in h. Most of the time the soil was a sink for methane, but less CH4 was oxidized in the soil of h plots. Emission of N2O did not have good correlation with air humidity, although one could observe a clear tendency of bigger N2O fluxes when soil was continuously water-saturated. Expectedly, soil respiration had strong positive correlations with soil temperature and CH4 emission demonstrated strong positive correlation with SWP. Hence, interaction of humidification and precipitation affected greenhouse gas fluxes. IPCC, Climate Change 2007: The Physical Science Basis. Cambridge University Press, Cambridge. 2007. Tullus A, Kupper P, Sellin A, Parts L, Sõber J

  13. Multiproxy Evidence for a Positive Hydrological Budget during the Little Ice Age in the East African Rift, Kenya

    NASA Astrophysics Data System (ADS)

    Goman, M.; Ashley, G. M.; Hover, V. C.; Owen, R.

    2011-12-01

    Hominin evolution took place in Africa during the Plio-Pleistocene and climate change is thought to be a factor, with Africa experiencing a general cooling and increasing aridification over the last several million years. Today, the climate of the East African Rift Valley of Kenya is characterized as semi-arid with evapotranspiration four times precipitation. Water resources are a valuable commodity for the many millions of inhabitants of the Valley. The short instrumental record shows precipitation fluctuates at sub-decadal timeframes as a result of the ENSO cycle; while during prehistory variations in monsoonal precipitation occurred on Milankovitch timescales (i.e. African Humid Period). Both timescales exhibit significant impacts on the distribution of surface water. However, little is known regarding precipitation variability over sub-millennial timescales. Emerging paleoclimate data indicates that the near surface presence of water has also varied over century length timescales. We present paleoclimate data from multiple sites along a north-south 600 km transect of the Gregory Rift Valley (Kenya) that indicate the region experienced wetter conditions during the Little Ice Age (A.D. 1400-1850). Our reconstructions of landscape and climate during this time frame rely upon a multiproxy and interdisciplinary approach. We discuss data from a variety of environmental settings (e.g. lakes, wetlands, and springs) that indicate an overall increase in hydrologic balance. Evidence is derived from biologic microfossils such as pollen, diatom and testate amoebae assemblages as well as inorganic components of the sedimentary record and geomorphic changes. The data differs significantly from studies undertaken to the west in Uganda and the Congo, where negative hydrologic balances occurred during the Little Ice Age. While the atmospheric dynamics causing this disparity are not yet recognized, interactions between the Intertropical Convergence Zone and the Congo Air Boundary

  14. Humidity Dependence of Adhesion for Silane Coated Microcantilevers

    SciTech Connect

    DE BOER,MAARTEN P.; MAYER,THOMAS M.; CARPICK,ROBERT W.; MICHALSKE,TERRY A.; SRINIVASAN,U.; MABOUDIAN,R.

    1999-11-09

    This study examines adhesion between silane-coated micromachined surfaces that are exposed to humid conditions. Our quantitative values for interfacial adhesion energies are determined from an in-situ optical measurement of deformations in partly-adhered cantilever beams. We coated micromachined cantilevers with either ODTS (C{sub 18}H{sub 37}SiCl{sub 3}) or FDTS (C{sub 8}F{sub 17}C{sub 2}H{sub 4}SiCl{sub 3}) with the objective of creating hydrophobic surfaces whose adhesion would be independent of humidity. In both cases, the adhesion energy is significantly lower than for uncoated, hydrophilic surfaces. For relative humidities (RH) less than 95% (ODTS) and 80% (FDTS) the adhesion energy was extremely low and constant. In fact, ODTS-coated beams exposed to saturated humidity conditions and long (48 hour) exposures showed only a factor of two increase in adhesion energy. Surprisingly, FDTS coated beams, which initially have a higher contact angle (115{degree}) with water than do ODTS coated beams (112{degree}), proved to be much more sensitive to humidity. The FDTS coated surfaces showed a factor of one hundred increase in adhesion energy after a seven hour exposure to 90% RH. Atomic force microscopy revealed agglomerated coating material after exposed to high RH, suggesting a redistribution of the monolayer film. This agglomeration was more prominent for FDTS than ODTS. These findings suggest a new mechanism for uptake of moisture under high humidity conditions. At high humidities, the silane coatings can reconfigure from a surface to a bulk phase leaving behind locally hydrophilic sites which increase the average measured adhesion energy. In order for the adhesion increase to be observed, a significant fraction of the monolayer must be converted from the surface to the bulk phase.

  15. Effects of Humidity and Solution Viscosity on Electrospun Fiber Morphology

    PubMed Central

    Nezarati, Roya M.; Eifert, Michelle B.

    2013-01-01

    Electrospinning is a popular technique to fabricate tissue engineering scaffolds due to the exceptional tunability of fiber morphology that can be used to control scaffold mechanical properties, degradation rate, and cell behavior. Although the effects of modulating processing or solution parameters on fiber morphology have been extensively studied, there remains limited understanding of the impact of environmental parameters such as humidity. To address this gap, three polymers (poly(ethylene glycol) [PEG], polycaprolactone [PCL], and poly(carbonate urethane) [PCU]) were electrospun at a range of relative humidities (RH=5%–75%) and the resulting fiber architecture characterized with scanning electron microscopy. Low relative humidity (<50%) resulted in fiber breakage for all three polymers due to decreased electrostatic discharge from the jet. At high relative humidity (>50%), three distinct effects were observed based on individual polymer properties. An increase in fiber breakage and loss of fiber morphology occurred in the PEG system as a result of increased water absorption at high relative humidity. In contrast, surface pores on PCL fibers were observed and hypothesized to have formed via vapor-induced phase separation. Finally, decreased PCU fiber collection occurred at high humidity likely due to increased electrostatic discharge. These findings highlight that the effects of relative humidity on electrospun fiber morphology are dependent on polymer hydrophobicity, solvent miscibility with water, and solvent volatility. An additional study was conducted to highlight that small changes in molecular weight can strongly influence solution viscosity and resulting fiber morphology. We propose that solution viscosity rather than concentration is a more useful parameter to report in electrospinning methodology to enable reproduction of findings. In summary, this study further elucidates key mechanisms in electrospun fiber formation that can be utilized to

  16. Variation of elastic moduli of clays with humidity

    NASA Astrophysics Data System (ADS)

    Kuila, U.; Prasad, M.

    2012-12-01

    The elastic moduli of clays are highly variable. The reported values of elastic moduli of clays in the literature provide a large range: ranging from 0.15 GPa to 400 GPa. One of the many probable reasons for this variation is different external experimental environments leading to varied amounts of cations and bound water in the interlayers. The clay structure is affected by the kind of water associated with it: free water and bound water, the water in the interlayer. Smectite and mixed-layered illite-smectite (I-S) are capable of retaining significant electrostatic bound water in excess of 200C and can rapidly adsorb moisture from the air depending upon the humidity conditions. These can lead to the variation in their elastic properties. Prior experimental studies of acoustic velocity measurement in compacted clay pellets showed comparable trends (Figure 1) but different velocities for same reported porosity. This can be attributed to the humidity difference in the lab ambient conditions where the measurements were made. Molecular simulation studies on montmorillonite clays shows similar dependence of Young's Modulus on the hydration state of the clays (Pal Bathija 2009). In this paper, we studied the effect of humidity on the elastic properties of compacted pellets of Na-montmorillonite. This can be achieved by placing the Na-montmorillonite pellets in bell jars containing different saturated salt solutions. These salt solutions are used as a standard for relative humidity measurements. Figure 2 shows an experimental set-up used to the experiment. We will present the results of the variation of elastic properties of clays with varying humidity conditions. Preliminary results suggest that acoustic velocities through the compacted Na-montmorillonite pellet depend on the humidity conditions. The varying amount of interlayer clay-bound water and capillary condensation of water in small micropores in clays with varying humidity conditions resulted in the change in the

  17. Probabilistic models for assessment of extreme temperatures and relative humidity in Lithuania

    NASA Astrophysics Data System (ADS)

    Alzbutas, Robertas; Šeputytė, Ilona

    2015-04-01

    Extreme temperatures are fairly common natural phenomenon in Lithuania. They have mainly negative effects both on the environment and humans. Thus there are important to perform probabilistic and statistical analyzes of possibly extreme temperature values and their time-dependant changes. This is especially important in areas where technical objects (sensitive to the extreme temperatures) are foreseen to be constructed. In order to estimate the frequencies and consequences of possible extreme temperatures, the probabilistic analysis of the event occurrence and its uncertainty has been performed: statistical data have been collected and analyzed. The probabilistic analysis of extreme temperatures in Lithuanian territory is based on historical data taken from Lithuanian Hydrometeorology Service, Dūkštas Meteorological Station, Lithuanian Energy Institute and Ignalina NNP Environmental Protection Department of Environmental Monitoring Service. The main objective of performed work was the probabilistic assessment of occurrence and impact of extreme temperature and relative humidity occurring in whole Lithuania and specifically in Dūkštas region where Ignalina Nuclear Power Plant is closed for decommissioning. In addition, the other purpose of this work was to analyze the changes of extreme temperatures. The probabilistic analysis of extreme temperatures increase in Lithuanian territory was based on more than 50 years historical data. The probabilistic assessment was focused on the application and comparison of Gumbel, Weibull and Generalized Value (GEV) distributions, enabling to select a distribution, which has the best fit for data of extreme temperatures. In order to assess the likelihood of extreme temperatures different probabilistic models were applied to evaluate the probability of exeedance of different extreme temperatures. According to the statistics and the relationship between return period and probabilities of temperatures the return period for 30

  18. African Americans in Adult Education: The Harlem Renaissance Revisited

    ERIC Educational Resources Information Center

    Johnson-Bailey, Juanita

    2006-01-01

    This study examined a 25-year period of African Americans in adult education by accessing the archival holdings of three major data centers: the Schomburg Center for Research in Black Culture, the Moorland-Spingarn Archives, and the Hollis Burke Frissell Library. The sociopolitical context of the data was analyzed using a Black feminist…

  19. Developmental Trajectories of Maladaptive Perfectionism among African American Adolescents

    ERIC Educational Resources Information Center

    Herman, Keith C.; Wang, Kenneth; Trotter, Reid; Reinke, Wendy M.; Ialongo, Nicholas

    2013-01-01

    This study examined the developmental trajectories of maladaptive perfectionism over a 7-year period among African American youth living in an urban setting (N = 547). In particular, the study attempted to determine whether two maladaptive aspects of perfectionism (socially prescribed and self-critical) changed over time and could be distinguished…

  20. African-American Literature: Finding Biographical and Critical Sources.

    ERIC Educational Resources Information Center

    Van Noate, Judith, Comp.

    This guide is intended to help library patrons of the Atkins Library (at the University of North Carolina Charlotte) find sources of criticism on African-American literature. The guide explains important reference sources in the reference collection of the library and how to find biographical and critical information in books and periodicals. The…

  1. A Teacher's Guide to African Narratives. Studies in African Literature.

    ERIC Educational Resources Information Center

    O'Brien, Sara Talis

    This guide is designed to help secondary school teachers include African literature in their classes. It furnishes English and social studies teachers with a foundation for teaching African literature by offering critical commentary on the texts themselves. A synthesis of anthropological and historical material is presented to help both teachers…

  2. [An early warning method of cucumber downy mildew in solar greenhouse based on canopy temperature and humidity modeling].

    PubMed

    Wang, Hui; Li, Mei-lan; Xu, Jian-ping; Chen, Mei-xiang; Li, Wen-yong; Li, Ming

    2015-10-01

    The greenhouse environmental parameters can be used to establish greenhouse nirco-climate model, which can combine with disease model for early warning, with aim of ecological controlling diseases to reduce pesticide usage, and protecting greenhouse ecological environment to ensure the agricultural product quality safety. Greenhouse canopy leaf temperature and air relative humidity, models were established using energy balance and moisture balance principle inside the greenhouse. The leaf temperature model considered radiation heat transfer between the greenhouse crops, wall, soil and cover, plus the heat exchange caused by indoor net radiation and crop transpiration. Furthermore, the water dynamic balance in the greenhouse including leaf transpiration, soil evaporation, cover and leaf water vapor condensation, was considered to develop a relative humidity model. The primary infection and latent period warning models for cucumber downy mildew (Pseudoperonospora cubensis) were validated using the results of the leaf temperature and relative humidity model, and then the estimated disease occurrence date of cucumber downy mildew was compared with actual disease occurrence date of field observation. Finally, the results were verified by the measured temperature and humidity data of September and October, 2014. The results showed that the root mean square deviations (RMSDs) of the measured and estimated leaf temperature were 0.016 and 0.024 °C, and the RMSDs of the measured and estimated air relative humidity were 0.15% and 0.13%, respectively. Combining the result of estimated temperature and humidity models, a cucumber disease early warning system was established to forecast the date of disease occurrence, which met with the real date. Thus, this work could provide the micro-environment data for the early warning system of cucumber diseases in solar greenhouses. PMID:26995910

  3. Effect of humidity on the filter pressure drop

    SciTech Connect

    Vendel, J.; Letourneau, P.

    1995-02-01

    The effects of humidity on the filter pressure drop have been reported in some previous studies in which it is difficult to draw definite conclusions. These studies show contradictory effects of humidity on the pressure drop probably due to differences in the hygroscopicity of the test aerosols. The objective of this paper is to present experimental results on the evolution of the filter pressure drop versus mass loading, for different test aerosols and relative humidities. Present results are compared to those found in various publication. An experimental device has been designed to measure filter pressure drop as the function of the areal density for relative humidity varying in the range of 9 % to 85 %. Experiments have been conducted with hygroscopic: (CsOH) and nonhygroscopic aerosols (TiO{sub 2}). Cesium hydroxyde (CsOH) of size of 2 {mu} M AMMD has been generated by an ultrasonic generator and the 0.7 {mu}m AMMD titanium oxyde has been dispersed by a {open_quotes}turn-table{close_quotes} generator. As it is noted in the BISWAS`publication [3], present results show, in the case of nonhygroscopic aerosols, a linear relationship of pressure drop to mass loading. For hygroscopic aerosols two cases must be considered: for relative humidity below the deliquescent point of the aerosol, the relationship of pressure drop to mass loading remains linear; above the deliquescent point, the results show a sudden increase in the pressure drop and the mass capacity of the filter is drastically reduced.

  4. Thermistors Used in Climatic Chamber at High Temperature and Humidity

    NASA Astrophysics Data System (ADS)

    van Geel, J. L. W. A.; Bosma, R.; van Wensveen, J.; Peruzzi, A.

    2015-03-01

    In 2011, VSL initiated the development of a facility for a relative humidity between and for calibrating high-temperature relative humidity sensors at pressures other than atmospheric. The setup for calculating the relative humidity uses the dew-point temperature, measured by a chilled mirror hygrometer, and the temperature distribution in the chamber, measured by a series of thermistors. This paper describes the results of thermal tests performed on the thermistors to ensure that they meet the requirements of the humidity calibration facility. Different types of thermistors were evaluated up to , and the selected type showed a short-term drift of less than 2 mK. Exposure of these thermistors to temperatures up to gave an initial hysteresis of 40 mK, but after this initial hysteresis, the hysteresis, over the range from up to , was less than 10 mK. Use of a digital multimeter, with a low-power option, limited the self-heating of the thermistors, over the range from up to , to less than 5 mK. During use in the new setup, the thermistors were exposed to changing humidities between 1 %Rh and 90 %Rh and temperatures up to , showing drifts of less than 10 mK.

  5. Application for temperature and humidity monitoring of data center environment

    NASA Astrophysics Data System (ADS)

    Albert, Ş.; Truşcǎ, M. R. C.; Soran, M. L.

    2015-12-01

    The technology and computer science registered a large development in the last years. Most systems that use high technologies require special working conditions. The monitoring and the controlling are very important. The temperature and the humidity are important parameters in the operation of computer systems, industrial and research, maintaining it between certain values to ensure their proper functioning being important. Usually, the temperature is maintained in the established range using an air conditioning system, but the humidity is affected. In the present work we developed an application based on a board with own firmware called "AVR_NET_IO" using a microcontroller ATmega32 type for temperature and humidity monitoring in Data Center of INCDTIM. On this board, temperature sensors were connected to measure the temperature in different points of the Data Center and outside of this. Humidity monitoring is performed using data from integrated sensors of the air conditioning system, thus achieving a correlation between humidity and temperature variation. It was developed a software application (CM-1) together with the hardware, which allows temperature monitoring and register inside Data Center and trigger an alarm when variations are greater with 3°C than established limits of the temperature.

  6. African-American Sacred Music.

    ERIC Educational Resources Information Center

    Bailey, A. Peter

    1991-01-01

    The history of African-American sacred music is traced from the time of slavery to the present interest in gospel music. The religious music of African Americans is geared toward liberation themes. It is important that this music does not dilute its power through cross-over with other music forms. (SLD)

  7. The interrelationship between dengue incidence and diurnal ranges of temperature and humidity in a Sri Lankan city and its potential applications

    PubMed Central

    Ehelepola, N. D. B.; Ariyaratne, Kusalika

    2015-01-01

    Background Temperature, humidity, and other weather variables influence dengue transmission. Published studies show how the diurnal fluctuations of temperature around different mean temperatures influence dengue transmission. There are no published studies about the correlation between diurnal range of humidity and dengue transmission. Objective The goals of this study were to determine the correlation between dengue incidence and diurnal fluctuations of temperature and humidity in the Sri Lankan city of Kandy and to explore the possibilities of using that information for better control of dengue. Design We calculated the weekly dengue incidence in Kandy during the period 2003–2012, after collecting data on all of the reported dengue patients and estimated midyear populations. Data on daily maximum and minimum temperatures and night-time and daytime humidity were obtained from two weather stations, averaged, and converted into weekly data. The number of days per week with a diurnal temperature range (DTR) of >10°C and <10°C and the number of days per week with a diurnal humidity range (DHR) of >20 and <15% were calculated. Wavelet time series analysis was performed to determine the correlation between dengue incidence and diurnal ranges of temperature and humidity. Results There were negative correlations between dengue incidence and a DTR >10°C and a DHR >20% with 3.3-week and 4-week lag periods, respectively. Additionally, positive correlations between dengue incidence and a DTR <10°C and a DHR <15% with 3- and 4-week lag periods, respectively, were discovered. Conclusions These findings are consistent with the results of previous entomological studies and theoretical models of DTR and dengue transmission correlation. It is important to conduct similar studies on diurnal fluctuations of humidity in the future. We suggest ways and means to use this information for local dengue control and to mitigate the potential effects of the ongoing global reduction of

  8. Searching for the best modeling specification for assessing the effects of temperature and humidity on health: a time series analysis in three European cities

    NASA Astrophysics Data System (ADS)

    Rodopoulou, Sophia; Samoli, Evangelia; Analitis, Antonis; Atkinson, Richard W.; de'Donato, Francesca K.; Katsouyanni, Klea

    2015-11-01

    Epidemiological time series studies suggest daily temperature and humidity are associated with adverse health effects including increased mortality and hospital admissions. However, there is no consensus over which metric or lag best describes the relationships. We investigated which temperature and humidity model specification most adequately predicted mortality in three large European cities. Daily counts of all-cause mortality, minimum, maximum and mean temperature and relative humidity and apparent temperature (a composite measure of ambient and dew point temperature) were assembled for Athens, London, and Rome for 6 years between 1999 and 2005. City-specific Poisson regression models were fitted separately for warm (April-September) and cold (October-March) periods adjusting for seasonality, air pollution, and public holidays. We investigated goodness of model fit for each metric for delayed effects up to 13 days using three model fit criteria: sum of the partial autocorrelation function, AIC, and GCV. No uniformly best index for all cities and seasonal periods was observed. The effects of temperature were uniformly shown to be more prolonged during cold periods and the majority of models suggested separate temperature and humidity variables performed better than apparent temperature in predicting mortality. Our study suggests that the nature of the effects of temperature and humidity on mortality vary between cities for unknown reasons which require further investigation but may relate to city-specific population, socioeconomic, and environmental characteristics. This may have consequences on epidemiological studies and local temperature-related warning systems.

  9. African climate change and faunal evolution during the Pliocene-Pleistocene

    NASA Astrophysics Data System (ADS)

    deMenocal, Peter B.

    2004-03-01

    Environmental theories of African faunal evolution state that important evolutionary changes during the Pliocene-Pleistocene interval (the last ca. 5.3 million years) were mediated by changes in African climate or shifts in climate variability. Marine sediment sequences demonstrate that subtropical African climate periodically oscillated between markedly wetter and drier conditions, paced by earth orbital variations, with evidence for step-like (±0.2 Ma) increases in African climate variability and aridity near 2.8 Ma, 1.7 Ma, and 1.0 Ma, coincident with the onset and intensification of high-latitude glacial cycles. Analysis of the best dated and most complete African mammal fossil databases indicates African faunal assemblage and, perhaps, speciation changes during the Pliocene-Pleistocene, suggesting more varied and open habitats at 2.9-2.4 Ma and after 1.8 Ma. These intervals correspond to key junctures in early hominid evolution, including the emergence of our genus Homo. Pliocene-Pleistocene shifts in African climate, vegetation, and faunal assemblages thus appear to be roughly contemporary, although detailed comparisons are hampered by sampling gaps, dating uncertainties, and preservational biases in the fossil record. Further study of possible relations between African faunal and climatic change will benefit from the accelerating pace of important new fossil discoveries, emerging molecular biomarker methods for reconstructing African paleovegetation changes, tephra correlations between terrestrial and marine sequences, as well as continuing collaborations between the paleoclimatic and paleoanthropological communities.

  10. Climatology of free tropospheric humidity: Extension into the SEVIRI era, evaluation and exemplary analysis

    NASA Astrophysics Data System (ADS)

    Schröder, Marc; Roca, Rémy; Picon, Laurence; Kniffka, Anke; Brogniez, Hélène; Dietzsch, Felix

    2015-04-01

    Water vapour has an amplifying role in a warming environment through a strong positive climate feedback loop as evident in climate predictions, and this water vapour feedback loop is dominated by water vapour in the tropical free troposphere (Held and Soden, 2000). The importance of humidity in the free troposphere originates from the non-linear interaction between humidity and long-wave radiation. The outgoing longwave radiation (OLR) is much more sensitive to perturbations at the dry end than at the moist part of the distribution (Spencer and Braswell, 1997; Roca et al., 2011). Sherwood et al. (2010a) recently reviewed the processes that determine the humidity distribution in the intertropical region. They emphasize the strong connection between the large scale dynamics and water vapour and the roles of eddies (mesoscale convection, circulation transients) in establishing these links pointing out to a broad range of scale implied in the humidity distribution. They further indicate that there is a need to better constrain the available theory. Satellites that observe the humidity of the free troposphere, and particularly, geostationary platforms are very well suited to contribute to this constraint by providing observations at kilometres and hours scale resolution over a 30 years long period. A new free tropospheric humidity (FTH) data record is presented. It is based on observations of Meteosat-2 - 5 and Meteosat-7 Meteosat Visible and Infrared Imager (MVIRI) and Meteosat-8 and -9 Spinning Enhanced Visible and Infrared Imager (SEVIRI) at the water absorption band at 6.3 µm. With the extension to SEVIRI observations the data record now covers the period 1983 - 2009 with a spatial and temporal resolution of 0.625° and 3 hours, respectively. The data record is freely available from http://www.cmsaf.eu/wui. The relation between the observed brightness temperature (BT) and FTH is well established: Here, existing retrievals have been refined mainly through the

  11. Effects of cool and hot humid environmental conditions on neuroendocrine responses of horses to treadmill exercise.

    PubMed

    Williams, R J; Marlin, D J; Smith, N; Harris, R C; Haresign, W; Davies Morel, M C

    2002-07-01

    To determine the effects of exercise, high heat and humidity and acclimation on plasma adrenaline, noradrenaline, beta-endorphin and cortisol concentrations, five horses performed a competition exercise test (CET; designed to simulate the speed and endurance test of a three-day event) in cool dry (CD) (20 degrees C/40% RH) and hot humid (30 degrees C/80% RH) conditions before (pre-acclimation) and after (post-acclimation) a 15 day period of humid heat acclimation. Plasma adrenaline and noradrenaline concentrations pre-acclimation were significantly increased compared with exercise in the CD trial at the end of Phases C (P<0.05) and D (P<0.05 and P<0.01, respectively) and at 2 min recovery (P<0.01), with adrenaline concentrations still elevated after 5 min of recovery (P<0.001). Plasma beta-endorphin concentrations were increased at the end of Phases C (P<0.05) and X (P<0.01) and at 5 and 30 min recovery (P<0.05) in the pre-acclimation session. Plasma cortisol concentrations were elevated after the initial warm up period pre-acclimation (P<0.01) and at the end of Phase C (P<0.05), compared with the CD trial. A 15 day period of acclimation significantly increased plasma adrenaline concentrations at 2 min recovery (P<0.001) and plasma cortisol concentration at the end of Phase B (P<0.01) compared with pre-acclimation. Acclimation did not significantly influence noradrenaline or beta-endorphin responses to exercise, although there was a trend for plasma beta-endorphin to be lower at the end of Phases C and X and after 30 min recovery compared with pre-acclimation. Plasma adrenaline, noradrenaline, beta-endorphin and cortisol concentrations were increased by exercise in cool dry conditions and were further increased by the same exercise in hot humid conditions. Exercise responses post-acclimation suggest that adrenaline and noradrenaline may play a role in the adaptation of horses to thermal stress and that changes in plasma beta-endorphin concentrations could be used

  12. Thermal Comfort in the Hot Humid Tropics of Australia

    PubMed Central

    Wyndham, C. H.

    1963-01-01

    Day and night comfort votes were recorded from Caucasian residents at Weipa, a mission station in the hot humid tropics of North Queensland, Australia. The limit of day comfort for more than 50% of the men was 81·5°F. (27·5°C.) “normal” corrected effective temperature; the night limit was 78·0°F. (25·5°C.). Day comfort limits correlated well with air conditions at which sweat was apparent: night limits correlated with the amount of bed covering. Evidence of a change over 14 days in day comfort limit was found. Limitations in the effective temperature scale for expressing the “oppressive nature” of night air conditions are pointed out. Criticism is voiced of the use of dry bulb temperature instead of the effective temperature scale in conditions of high wet bulb temperatures with high relative humidity, such as in the hot humid tropics. PMID:14002126

  13. Humidity insensitive TOPAS polymer fiber Bragg grating sensor.

    PubMed

    Yuan, Wu; Khan, Lutful; Webb, David J; Kalli, Kyriacos; Rasmussen, Henrik K; Stefani, Alessio; Bang, Ole

    2011-09-26

    We report the first experimental demonstration of a humidity insensitive polymer optical fiber Bragg grating (FBG), as well as the first FBG recorded in a TOPAS polymer optical fiber in the important low loss 850 nm spectral region. For the demonstration we have fabricated FBGs with resonance wavelength around 850 nm and 1550 nm in single-mode microstructured polymer optical fibers made of TOPAS and the conventional poly (methyl methacrylate) (PMMA). Characterization of the FBGs shows that the TOPAS FBG is more than 50 times less sensitive to humidity than the conventional PMMA FBG in both wavelength regimes. This makes the TOPAS FBG very appealing for sensing applications as it appears to solve the humidity sensitivity problem suffered by the PMMA FBG. PMID:21996915

  14. Exposure of Bed Bugs to Metarhizium anisopliae at Different Humidities.

    PubMed

    Ulrich, Kevin R; Feldlaufer, Mark F; Kramer, Matthew; St Leger, Raymond J

    2014-12-01

    Bed bugs Cimex lectularius L. were exposed to conidia (spores) of the entomopathogenic fungus Metarhizium anisopliae by feeding, aerosol spray, or contact with a treated surface. Feeding experiments demonstrated that bed bugs were innately susceptible to this fungus. However, only at 98% humidity were mortality rates high, regardless of whether bed bugs were sprayed with a fungal solution or contacted a treated surface. Mortality in treated bed bugs at ambient humidity did not increase when these bed bugs were kept in aggregation with other bed bugs that had recently blood fed to repletion. Based on these laboratory studies, we conclude that M. anisopliae is a poor pathogen for use in control of bed bugs, particularly at humidities that would likely be encountered under field conditions. PMID:26470085

  15. Effect of environmental humidity on static foam stability.

    PubMed

    Li, Xueliang; Karakashev, Stoyan I; Evans, Geoffrey M; Stevenson, Paul

    2012-03-01

    The quality of foaming products (such as beer and shampoo) and the performance of industrial processes that harness foam (such as the froth flotation of minerals or the foam fractionation of proteins) depend upon foam stability. In this study, experiments are performed to study the effect of environmental humidity on the collapse of static foams. The dependency of the rate at which a foam collapses upon humidity is demonstrated, and we propose a hypothesis for bubble bursting due to Marangoni instability induced by nonuniform evaporation to help explain the dependency. This hypothesis is supported by direct experimental observations of the bursting process of isolated bubbles by high speed video recording and the thinning of isolated foam films under different values of humidity and temperature by microinterferometric methods. PMID:22303917

  16. Effect of Relative Humidity on Dynamic Aerosols of Adenovirus 12

    PubMed Central

    Davis, Gary W.; Griesemer, Richard A.; Shadduck, John A.; Farrell, Robert L.

    1971-01-01

    Dynamic aerosols of adenovirus 12 were generated in the same Henderson apparatus under conditions of high, medium, and low relative humidity. High relative humidities resulted in more recovery of adenovirus 12 from aerosols and lungs of newborn Syrian hamsters. At 89, 51, and 32% relative humidity, the total infectious virus recovered from a 20-min aerosol was 106.7, 106.0, and 104.3 TCD50, respectively. Hamsters exposed to these 20-min aerosols retained measured lung doses of 103.0, 102.4, and 101.0 TCD50, respectively. The measured retained lung doses were compared to calculated inhaled lung doses based on both total virus aerosolized and total virus recovery from the aerosols. PMID:4930277

  17. The Chilled-Mirror Humidity Sensor: Improved Radiosonde Measurements

    NASA Technical Reports Server (NTRS)

    Schmidlin, F. J.

    1999-01-01

    Chilled-mirror humidity sensor technology recently was adapted for use with the VIZ radiosonde. The principle of the chilled-mirror operation is to lower its temperature until dew forms on the mirror, at that point the dew point temperature is noted and the mirror is then heated to evaporate the moisture. The cycle is repeated. Research conducted from NASA's Wallops Flight Facility has provided comparisons between the chilled-mirror sensor and the carbon hygristor of VIZ, and the capacitive sensors of AIR Inc. and Vaisala Co. We believe the chilled-mirror sensor is accurate and would serve as a reference standard for evaluating operational radiosonde relative humidity sensors. Thus, differences seen in the comparisons are beginning to furnish insight into developing better humidity sensors. We discuss these comparison results as well as reproducibility results from a dual chilled-mirror measurement.

  18. Improved Humidity Sensing with the Chilled Mirror: Really?

    NASA Technical Reports Server (NTRS)

    Schmidlin, Francis J.; Zukor, Dorothy (Technical Monitor)

    2001-01-01

    Testing of the chilled mirror sensor was initiated at Wallops Island in 1997. The chilled mirror dew point system is integrated with the Sippican, Inc., MK2 radiosonde providing a relatively inexpensive instrument. Early tests suggested that better stratospheric humidity measurements might be available. But, recent tests with different configurations of the mirror's cooler indicated that the systems capability to cool to the very low dew point temperatures required in the stratosphere were not being met with the present system. Nonetheless, the present mirror technology, while still undergoing development gives better humidity information between 400 and 100 hPa than the current routine radiosonde sensor. Comparisons are given of the chilled mirror and the typical operational humidity sensors.

  19. The `Clear-Sky Bias' of TOVS Upper-Tropospheric Humidity.

    NASA Astrophysics Data System (ADS)

    Lanzante, John R.; Gahrs, Gregory E.

    2000-11-01

    A temporal sampling bias may be introduced due to the inability of a measurement system to produce a valid observation during certain types of situations. In this study the temporal sampling bias in satellite-derived measures of upper-tropospheric humidity (UTH) was examined through the utilization of similar humidity measures derived from radiosonde data. This bias was estimated by imparting the temporal sampling characteristics of the satellite system onto the radiosonde observations. This approach was applied to UTH derived from Television Infrared Observation Satellite (TIROS) Operational Vertical Sounder radiances from the NOAA-10 satellite from the period 1987-91 and from the `Angell' network of 63 radiosonde stations for the same time period. Radiative modeling was used to convert both the satellite and radiosonde data to commensurate measures of UTH.Examination of the satellite temporal sampling bias focused on the effects of the `clear-sky bias' due to the inability of the satellite system to produce measurements when extensive cloud cover is present. This study indicates that the effects of any such bias are relatively small in the extratropics (about several percent relative humidity) but may be 5%-10% in the most convectively active regions in the Tropics. Furthermore, there is a systematic movement and evolution of the bias pattern following the seasonal migration of convection, which reflects the fact that the bias increases as cloud cover increases. The bias is less noticeable for shorter timescales (seasonal values) but becomes more obvious as the averaging time increases (climatological values); it may be that small-scale noise partially obscures the bias for shorter time averages. Based on indirect inference it is speculated that the bias may lead to an underestimate of the magnitude of trends in satellite UTH in the Tropics, particularly in the drier regions.

  20. Community-based chronic disease management program for African Americans.

    PubMed

    Nine, Susan L; Lakies, Charlotte L; Jarrett, Helen Kay; Davis, Barbara A

    2003-01-01

    Seventy-five predominately African American volunteers were enrolled in a community-based intervention program designed to lower blood pressure and HgbA1C levels in an African American population. Program components consisted of exercise, meal planning, weekly support groups, periodic cooking schools, and service coordination. Significant decreases in initial and 1-year values were seen in both systolic blood pressure (P < .0001) and diastolic blood pressure (P = .000) and HgbA1Cs for those with initial values > 7% (P = .013). PMID:12881971

  1. A contemporary assessment of change in humid tropical forests.

    PubMed

    Asner, Gregory P; Rudel, Thomas K; Aide, T Mitchell; Defries, Ruth; Emerson, Ruth

    2009-12-01

    In recent decades the rate and geographic extent of land-use and land-cover change has increased throughout the world's humid tropical forests. The pan-tropical geography of forest change is a challenge to assess, and improved estimates of the human footprint in the tropics are critical to understanding potential changes in biodiversity. We combined recently published and new satellite observations, along with images from Google Earth and a literature review, to estimate the contemporary global extent of deforestation, selective logging, and secondary regrowth in humid tropical forests. Roughly 1.4% of the biome was deforested between 2000 and 2005. As of 2005, about half of the humid tropical forest biome contained 50% or less tree cover. Although not directly comparable to deforestation, geographic estimates of selective logging indicate that at least 20% of the humid tropical forest biome was undergoing some level of timber harvesting between 2000 and 2005. Forest recovery estimates are even less certain, but a compilation of available reports suggests that at least 1.2% of the humid tropical forest biome was in some stage of long-term secondary regrowth in 2000. Nearly 70% of the regrowth reports indicate forest regeneration in hilly, upland, and mountainous environments considered marginal for large-scale agriculture and ranching. Our estimates of the human footprint are conservative because they do not resolve very small-scale deforestation, low-intensity logging, and unreported secondary regrowth, nor do they incorporate other impacts on tropical forest ecosystems, such as fire and hunting. Our results highlight the enormous geographic extent of forest change throughout the humid tropics and the considerable limitations of the science and technology available for such a synthesis. PMID:20078639

  2. Humidity and temperature response of photopolymer-based holographic gratings

    NASA Astrophysics Data System (ADS)

    Mikulchyk, Tatsiana; Walshe, James; Cody, Dervil; Martin, Suzanne; Naydenova, Izabela

    2015-05-01

    Holographic sensors have significant potential in various applications ranging from in vitro diagnostics to optical security. They are capable of providing fast, real-time, reversible or irreversible, visual colorimetric or optical readouts. The main challenge in the development of holographic sensors is to improve their selectivity by functionalizing the holographic recording material and achieve a response to a specific analyte. This material should be permeable to the analyte and its properties should change under exposure to the analyte. This work explores the humidity and temperature response of volume phase gratings recorded in photopolymers containing acrylamide and diacetone acrylamide as monomers, and triethanolamine and N-phenylglycine as photoinitiators. Characterization of the humidity response of photopolymer-based gratings in the relative humidity (RH) range of 20-90 % was carried out by measuring the diffraction efficiency of slanted transmission gratings and the position of the maximum intensity in the spectral response of reflection gratings. A strong humidity dependence of the diffraction efficiency of diacetone acrylamide-based transmission gratings was observed at RH=20-90%. The humidity dependence of the spectral response of the reflection gratings showed that photopolymers containing triethanolamine are more hydrophilic than photopolymers containing N-phenylglycine. The temperature response of slanted transmission gratings was investigated in the temperature (T) range of 20-60 °C. Exposure of the photopolymer layers containing triethanolamine to elevated temperature showed that the observed Bragg angle shift was caused by layer shrinkage due to water evaporation. The application of a sealing technique allowed for the observation of the photopolymer layer swelling due to the layer's thermal expansion. The results demonstrate an effective approach to obtaining photopolymer-based gratings with tuneable temperature and humidity sensitivity.

  3. Measured impacts of supermarket humidity level on defrost performance and refrigerating system energy use

    SciTech Connect

    Henderson, H.I.; Khattar, M.

    1999-07-01

    This paper presents field-monitor data from two supermarkets where the impact of space humidity on refrigerating system energy use was evaluated. Direct digital control (DDC) systems were used at both stores to collect 15-minute monitored data. At Store A in Minneapolis, the DDC system was used to monitor system performance as well as to implement temperature-terminated control in place of time-terminated control on 16 refrigerated zones using hot gas defrost. At Store B in Indianapolis, the DDC system was used to quantify the performance trends for the single compressor rack system with electric defrost. The results at Store B showed that refrigerating system energy use decreases by nearly 10 kWh/day for each 1% drop in space relative humidity, or about 0.4% of average annual system energy use. This value includes the impact of reduced latent loads, the reduction in direct energy use and imposed load from reduced electric defrost heater operation, and the smaller imposed load from reduced anti-sweat heater energy use. The measured reductions agree well with the impact predicted using the calculation methods developed by Howell (1933b) in ASHRAE Research Project 596. At Store A, the measured data show that implementing temperature-terminated defrost reduced refrigerating system energy use by nearly 70 kWh/day over the winter period when the average space humidity was 22% RH. The savings from temperature-terminated defrost increase by 4 kWh/day per each 1% drop in relative humidity. At both stores, the same type of mechanical controls were used to duty cycle the anti-sweat heaters based on store dew point. Anti-sweat heater electricity use was observed to decrease by 4.6 kWh/day at Store B and 3.4 kWh/day at Store A for each 1% drop in relative humidity. At Store A, a more aggressive control scheme was implemented with the DDC system that reduced anti-sweat heater energy use by 7.8 kWh/day per % RH. The more aggressive control approach was reported to properly

  4. Humidity response of the Eberline model PAC-7 alpha instrument

    SciTech Connect

    McAtee, J.L.

    1981-04-01

    Response of the Eberline Model PAC-7 alpha instrument under varying relative humidity (RH) and temperature conditions was studied in an environmental chamber. Electric discharges resulting in spurious counts or in instrument paralysis occurred at 35 to 50% RH. Improvement in the RH level tolerated by the PAC-7 alpha instrument was obtained by conformal coating of the high-voltage region of the printed circuit (PC) board. Following this treatment, electric discharges occurred only at relatively high humidity levels and then as a result of high-voltage breakdown within the AC-24C probe rather than within the PC board.

  5. Humidity and pressure sensor based on internal reflection.

    PubMed

    Domenegueti, J F M; Zilio, S C

    2014-03-10

    A low-cost humidity and pressure optical sensor, based on the internal reflection phenomenon, is presented. It takes advantage of the phase difference acquired by s- and p-polarized light undergoing internal reflection to generate an easily detectable minimum in the reflected profile, in a position corresponding to the critical angle. The apparatus presents good sensitivity to relative humidity changes above 70% and a response time below one second. The same device is also capable of measuring changes in pressure and can be used as a vacuum gauge between 1 and 1000 mbar. PMID:24663415

  6. Encapsulation for smart textile electronics - humidity and temperature sensor.

    PubMed

    Larsson, Andreas; Tran, Thanh-Nam; Aasmundtveit, Knut E; Seeberg, Trine M

    2015-01-01

    A combined humidity and temperature sensor was packaged by vacuum casting onto three different types of textiles; cotton, nylon and a waterproof fabric. This was done in order to integrate the sensor in a jacket in a soft and reliable way without changing the sensor performance. A membrane was custom made and integrated into the device to protect the sensor from the environment. The packaged sensors performance was characterized in a climate chamber were the relative humidity and temperature ranged from 25 % to 95 % and -10 °C to 75 °C respectively. The packaged sensors showed insignificant to limited performance degradation. PMID:25980871

  7. Effect of humidity on fretting wear of several pure metals

    NASA Technical Reports Server (NTRS)

    Goto, H.; Buckley, D. H.

    1984-01-01

    Fretting wear experiments with several pure metals were conducted in air at various relative humidity levels. The materials used were iron, aluminum, copper, silver, chromium, titanium, and nickel. Each pure metal had a maximum fretting wear volume at a specific humidity level RH sub max that was not dependent on mechanical factors such as contact load, fretting amplitude, and frequency in the ranges studied. The weight loss due to fretting wear at RH sub max for each pure metal decreased with increasing heat of oxygen adsorption on the metal, indicating that adhesive wear dominated at RH sub max.

  8. Challenges to Cabin Humidity Removal Presented by Intermittent Condensing Conditions

    NASA Technical Reports Server (NTRS)

    vonJouanne, Roger G.; Williams, David E.

    2007-01-01

    On-orbit temperature and humidity control (THC) is more easily accomplished when the THC hardware is either consistently dry (i.e., no humidity control is occurring), or consistently wet. The system is especially challenged when intermittent wet/dry conditions occur. The first six years of on-orbit ISS operations have revealed specific concerns within the THC system, specifically in the condensing heat exchanger and the downstream air/water separator. Failed or degraded hardware has been returned to ground and investigated. This paper presents the investigation findings, and the recommended hardware and procedural revisions to prevent and recover from the effects of intermittent condensing conditions.

  9. Temperature, Humidity, Wind and Pressure Sensors (THWAPS) Handbook

    SciTech Connect

    Ritsche, MT

    2011-01-17

    The temperature, humidity, wind, and pressure system (THWAPS) provide surface reference values of these measurements for balloon-borne sounding system (SONDE) launches. The THWAPS is located adjacent to the SONDE launch site at the Southern Great Plains (SGP) Central Facility. The THWAPS system is a combination of calibration-quality instruments intended to provide accurate measurements of meteorological conditions near the surface. Although the primary use of the system is to provide accurate surface reference values of temperature, pressure, relative humidity (RH), and wind velocity for comparison with radiosonde readings, the system includes a data logger to record time series of the measured variables.

  10. Uncertainties in downscaled relative humidity for a semi-arid region in India

    NASA Astrophysics Data System (ADS)

    Anandhi, Aavudai

    2011-06-01

    Monthly scenarios of relative humidity ( R H) were obtained for the Malaprabha river basin in India using a statistical downscaling technique. Large-scale atmospheric variables (air temperature and specific humidity at 925 mb, surface air temperature and latent heat flux) were chosen as predictors. The predictor variables are extracted from the (1) National Centers for Environmental Prediction reanalysis dataset for the period 1978-2000, and (2) simulations of the third generation Canadian Coupled Global Climate Model for the period 1978-2100. The objective of this study was to investigate the uncertainties in regional scenarios developed for R H due to the choice of emission scenarios (A1B, A2, B1 and COMMIT) and the predictors selected. Multi-linear regression with stepwise screening is the downscaling technique used in this study. To study the uncertainty in the regional scenarios of R H, due to the selected predictors, eight sets of predictors were chosen and a downscaling model was developed for each set. Performance of the downscaling models in the baseline period (1978-2000) was studied using three measures (1) Nash-Sutcliffe error estimate ( E f), (2) mean absolute error (MAE), and (3) product moment correlation ( P). Results show that the performances vary between 0.59 and 0.68, 0.42 and 0.50 and 0.77 and 0.82 for E f, MAE and P. Cumulative distribution functions were prepared from the regional scenarios of R H developed for combinations of predictors and emission scenarios. Results show a variation of 1 to 6% R H in the scenarios developed for combination of predictor sets for baseline period. For a future period (2001-2100), a variation of 6 to 15% R H was observed for the combination of emission scenarios and predictors. The variation was highest for A2 scenario and least for COMMIT and B1 scenario.

  11. African oil plays

    SciTech Connect

    Clifford, A.J. )

    1989-09-01

    The vast continent of Africa hosts over eight sedimentary basins, covering approximately half its total area. Of these basins, only 82% have entered a mature exploration phase, 9% have had little or no exploration at all. Since oil was first discovered in Africa during the mid-1950s, old play concepts continue to bear fruit, for example in Egypt and Nigeria, while new play concepts promise to become more important, such as in Algeria, Angola, Chad, Egypt, Gabon, and Sudan. The most exciting developments of recent years in African oil exploration are: (1) the Gamba/Dentale play, onshore Gabon; (2) the Pinda play, offshore Angola; (3) the Lucula/Toca play, offshore Cabinda; (4) the Metlaoui play, offshore Libya/Tunisia; (5) the mid-Cretaceous sand play, Chad/Sudan; and (6) the TAG-I/F6 play, onshore Algeria. Examples of these plays are illustrated along with some of the more traditional oil plays. Where are the future oil plays likely to develop No doubt, the Saharan basins of Algeria and Libya will feature strongly, also the presalt of Equatorial West Africa, the Central African Rift System and, more speculatively, offshore Ethiopia and Namibia, and onshore Madagascar, Mozambique, and Tanzania.

  12. Bioenergy and African transformation.

    PubMed

    Lynd, Lee R; Sow, Mariam; Chimphango, Annie Fa; Cortez, Luis Ab; Brito Cruz, Carlos H; Elmissiry, Mosad; Laser, Mark; Mayaki, Ibrahim A; Moraes, Marcia Afd; Nogueira, Luiz Ah; Wolfaardt, Gideon M; Woods, Jeremy; van Zyl, Willem H

    2015-01-01

    Among the world's continents, Africa has the highest incidence of food insecurity and poverty and the highest rates of population growth. Yet Africa also has the most arable land, the lowest crop yields, and by far the most plentiful land resources relative to energy demand. It is thus of interest to examine the potential of expanded modern bioenergy production in Africa. Here we consider bioenergy as an enabler for development, and provide an overview of modern bioenergy technologies with a comment on application in an Africa context. Experience with bioenergy in Africa offers evidence of social benefits and also some important lessons. In Brazil, social development, agricultural development and food security, and bioenergy development have been synergistic rather than antagonistic. Realizing similar success in African countries will require clear vision, good governance, and adaptation of technologies, knowledge, and business models to myriad local circumstances. Strategies for integrated production of food crops, livestock, and bioenergy are potentially attractive and offer an alternative to an agricultural model featuring specialized land use. If done thoughtfully, there is considerable evidence that food security and economic development in Africa can be addressed more effectively with modern bioenergy than without it. Modern bioenergy can be an agent of African transformation, with potential social benefits accruing to multiple sectors and extending well beyond energy supply per se. Potential negative impacts also cut across sectors. Thus, institutionally inclusive multi-sector legislative structures will be more effective at maximizing the social benefits of bioenergy compared to institutionally exclusive, single-sector structures. PMID:25709714

  13. Recent variations in surface specific humidity in the warm season over Japan

    NASA Astrophysics Data System (ADS)

    Iwasaki, Hiroyuki

    2016-02-01

    Recent variations in the warm seasonal mean of surface specific humidity ( q sfc) in Japan were studied using 34 years of data (1976-2009) from 150 meteorological observation stations of the Japan Meteorological Agency. The regional trend in the warm seasonal mean q sfc at 3 local standard time (LST) (UTC + 9 h), averaged over Japan, increased significantly with small changes in the relative humidity: the rate of increase was +1.93 g/kg per 100 years. The warm seasonal mean q sfc over Japan, calculated using four-times-daily data, increased slightly: the rate of increase was +0.95 g/kg per 100 years. About 16 % of the stations exhibited a significant increasing trend in warm seasonal mean q sfc calculated using four-times-daily data; these stations were concentrated in eastern Japan. The increasing trends at 40 % of the stations were more evident for the mean q sfc at 3 LST than at other local times. The local time at which the diurnal cycle of the mean q sfc reached a maximum was 15 LST in period 1 (1976-1992) and tended to be delayed until up to 21 LST in the interior in period 2 (1993-2009). In addition, the rate of increase in mean q sfc at nighttime was larger around the coastal and mountainous areas on days with well-developed thermally induced local circulation.

  14. The gendered character of the African petty bourgeoisie.

    PubMed

    Mcfadden, P

    1994-02-01

    have a gendered character." There is already evidence of men taking over positions previously held by women in this structural adjustment period. There is still the constant harassment by men, but African women want to be free of patriarchal definition and constraints. There are many difficulties in balancing power in intimate relationships. PMID:12319344

  15. Effects of ambient air temperature, humidity and rainfall on annual survival of adult little penguins Eudyptula minor in southeastern Australia.

    PubMed

    Ganendran, L B; Sidhu, L A; Catchpole, E A; Chambers, L E; Dann, P

    2016-08-01

    Seabirds are subject to the influences of local climate variables during periods of land-based activities such as breeding and, for some species, moult; particularly if they undergo a catastrophic moult (complete simultaneous moult) as do penguins. We investigated potential relationships between adult penguin survival and land-based climate variables (ambient air temperature, humidity and rainfall) using 46 years of mark-recapture data of little penguins Eudyptula minor gathered at a breeding colony on Phillip Island in southeastern Australia. Our results showed that adult penguin survival had a stronger association with land-based climate variables during the moult period, when birds were unable to go to sea for up to 3 weeks, than during the breeding period, when birds could sacrifice breeding success in favour of survival. Annual adult survival probability was positively associated with humidity during moult and negatively associated with rainfall during moult. Prolonged heat during breeding and moult had a negative association with annual adult survival. Local climate projections suggest increasing days of high temperatures, fewer days of rainfall which will result in more droughts (and by implication, lower humidity) and more extreme rainfall events. All of these predicted climate changes are expected to have a negative impact on adult penguin survival. PMID:26698160

  16. Effects of ambient air temperature, humidity and rainfall on annual survival of adult little penguins Eudyptula minor in southeastern Australia

    NASA Astrophysics Data System (ADS)

    Ganendran, L. B.; Sidhu, L. A.; Catchpole, E. A.; Chambers, L. E.; Dann, P.

    2015-12-01

    Seabirds are subject to the influences of local climate variables during periods of land-based activities such as breeding and, for some species, moult; particularly if they undergo a catastrophic moult (complete simultaneous moult) as do penguins. We investigated potential relationships between adult penguin survival and land-based climate variables (ambient air temperature, humidity and rainfall) using 46 years of mark-recapture data of little penguins Eudyptula minor gathered at a breeding colony on Phillip Island in southeastern Australia. Our results showed that adult penguin survival had a stronger association with land-based climate variables during the moult period, when birds were unable to go to sea for up to 3 weeks, than during the breeding period, when birds could sacrifice breeding success in favour of survival. Annual adult survival probability was positively associated with humidity during moult and negatively associated with rainfall during moult. Prolonged heat during breeding and moult had a negative association with annual adult survival. Local climate projections suggest increasing days of high temperatures, fewer days of rainfall which will result in more droughts (and by implication, lower humidity) and more extreme rainfall events. All of these predicted climate changes are expected to have a negative impact on adult penguin survival.

  17. Effects of ambient air temperature, humidity and rainfall on annual survival of adult little penguins Eudyptula minor in southeastern Australia

    NASA Astrophysics Data System (ADS)

    Ganendran, L. B.; Sidhu, L. A.; Catchpole, E. A.; Chambers, L. E.; Dann, P.

    2016-08-01

    Seabirds are subject to the influences of local climate variables during periods of land-based activities such as breeding and, for some species, moult; particularly if they undergo a catastrophic moult (complete simultaneous moult) as do penguins. We investigated potential relationships between adult penguin survival and land-based climate variables (ambient air temperature, humidity and rainfall) using 46 years of mark-recapture data of little penguins Eudyptula minor gathered at a breeding colony on Phillip Island in southeastern Australia. Our results showed that adult penguin survival had a stronger association with land-based climate variables during the moult period, when birds were unable to go to sea for up to 3 weeks, than during the breeding period, when birds could sacrifice breeding success in favour of survival. Annual adult survival probability was positively associated with humidity during moult and negatively associated with rainfall during moult. Prolonged heat during breeding and moult had a negative association with annual adult survival. Local climate projections suggest increasing days of high temperatures, fewer days of rainfall which will result in more droughts (and by implication, lower humidity) and more extreme rainfall events. All of these predicted climate changes are expected to have a negative impact on adult penguin survival.

  18. Assimilation Differences among Africans in America.

    ERIC Educational Resources Information Center

    Dodoo, F. Nii-Amoo

    1997-01-01

    Census data (1990) indicate that male African immigrants earn more than their Caribbean-born counterparts or native-born African Americans, but controlling for relevant earnings-related endowments erases the African advantage and elevates Caribbean earnings above those of the other groups. Also, African (but not Caribbean) university degree…

  19. Successfully Educating Our African-American Students

    ERIC Educational Resources Information Center

    Moncree-Moffett, Kareem

    2013-01-01

    The purpose of this empirical study was to explore the lived experiences of African American retired female teachers who have prior experience with educating urban African American students in public schools. Also explored are the experiences of active African American female teachers of urban African American students and comparisons are…

  20. Assessment of human thermal perception in the hot-humid climate of Dar es Salaam, Tanzania

    NASA Astrophysics Data System (ADS)

    Ndetto, Emmanuel L.; Matzarakis, Andreas

    2016-06-01

    Dar es Salaam, Tanzania, is a typical African city along the Indian Ocean coast, and therefore an important urban area to examine human thermal perception in the hot-humid tropical climate. Earlier research on human bioclimate at Dar es Salaam indicated that heat stress prevails during the hot season from October to March, peaking between December and February, particularly the early afternoons. In order to assess the human thermal perception and adaptation, two popular places, one at an urban park and another at a beach environment, were selected and questionnaire surveys were conducted in August-September 2013 and January 2014, concurrently with local micro-meteorological measurements at survey locations. The thermal conditions were quantified in terms of the thermal index of the physiologically equivalent temperature (PET) using the micro-scale climate model RayMan. The thermal comfort range of human thermal comfort and the local thermal adaptive capacity were determined in respect to the thermal index by binning thermal sensation votes. The thermal comfort range was found to be well above that in temperate climates at about 23-31 °C of PET. The study could significantly contribute to urban planning in Dar es Salaam and other coastal cities in the tropics.

  1. Family therapy with unmarried African American mothers and their adolescents.

    PubMed

    Becker, D; Liddle, H A

    2001-01-01

    Almost two-thirds of African American births are to unmarried mothers, and these single parents are among the most economically vulnerable in the United States. The effects of chronic stressors such as poverty can compromise the ability of these mothers to parent effectively, particularly during the developmental period of adolescence, typically a stressful phase of parenting. This article describes a multidimensional family therapy (MDFT) approach to working with African American adolescents who have drug and/or behavior problems. It is maintained that addressing the intrapersonal functioning of African American single mothers is vital if they are to re-establish the attachment bonds necessary for the maintenance of essential parental influence in the lives of their adolescents. Through systematic attention to the parent as an individual, leading to a balance between self-care and care for others, parental supervision is more easily achieved and relational impasses between parent and adolescent more equitably resolved. PMID:11802488

  2. Negro, Black, Black African, African Caribbean, African American or what? Labelling African origin populations in the health arena in the 21st century.

    PubMed

    Agyemang, Charles; Bhopal, Raj; Bruijnzeels, Marc

    2005-12-01

    Broad terms such as Black, African, or Black African are entrenched in scientific writings although there is considerable diversity within African descent populations and such terms may be both offensive and inaccurate. This paper outlines the heterogeneity within African populations, and discusses the strengths and limitations of the term Black and related labels from epidemiological and public health perspectives in Europe and the USA. This paper calls for debate on appropriate terminologies for African descent populations and concludes with the proposals that (1) describing the population under consideration is of paramount importance (2) the word African origin or simply African is an appropriate and necessary prefix for an ethnic label, for example, African Caribbean or African Kenyan or African Surinamese (3) documents should define the ethnic labels (4) the label Black should be phased out except when used in political contexts. PMID:16286485

  3. Effects of Humidity on Solid Oxide Fuel Cell Cathodes

    SciTech Connect

    Hardy, John S.; Stevenson, Jeffry W.; Singh, Prabhakar; Mahapatra, Manoj K.; Wachsman, E. D.; Liu, Meilin; Gerdes, Kirk R.

    2015-03-17

    This report summarizes results from experimental studies performed by a team of researchers assembled on behalf of the Solid-state Energy Conversion Alliance (SECA) Core Technology Program. Team participants employed a variety of techniques to evaluate and mitigate the effects of humidity in solid oxide fuel cell (SOFC) cathode air streams on cathode chemistry, microstructure, and electrochemical performance.

  4. Ensuring minimal humidity levels in hermetic implant housings.

    PubMed

    Schuettler, Martin; Schatz, Andreas; Ordonez, Juan S; Stieglitz, Thomas

    2011-01-01

    The electronic circuitry of active implantable devices is commonly protected against the risk of water-induced corrosion by using gas-tight (hermetic) packages, preventing moisture from the host body to reach the electronics. However, when closing the package, one has to ensure that the packaged components do not contain moisture that could rise humidity inside the package to critical levels by outgassing. For our miniature metal/ceramic packages, we found a drying procedure of 120 °C at 180 mbar absolute pressure for one hour, followed by a dry helium purge sufficient to keep the relative humidity below 2.5% over a time span of 300 days at 80 °C, corresponding to over 15 years at 37 °C. The additional integration of a desiccant inside the package permits to keep the relative humidity below 0.1%, the detection limit of the integrated sensor. This sensor was selected based on an evaluation of 17 commercially available humidity sensors. PMID:22254800

  5. Evaporation of Pesticide Droplets under Various Relative Humidity Conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Evaporation characteristics of five droplet sizes (246, 343, 575, 762 and 886 µm) under three relative humidity (RH) conditions (30%, 60% and 90%) were studied in a laboratory. Sequential images of evaporating droplets placed inside a small environmental-controlled chamber were obtained using a ster...

  6. A physically based analytical spatial air temperature and humidity model

    NASA Astrophysics Data System (ADS)

    Yang, Yang; Endreny, Theodore A.; Nowak, David J.

    2013-09-01

    Spatial variation of urban surface air temperature and humidity influences human thermal comfort, the settling rate of atmospheric pollutants, and plant physiology and growth. Given the lack of observations, we developed a Physically based Analytical Spatial Air Temperature and Humidity (PASATH) model. The PASATH model calculates spatial solar radiation and heat storage based on semiempirical functions and generates spatially distributed estimates based on inputs of topography, land cover, and the weather data measured at a reference site. The model assumes that for all grids under the same mesoscale climate, grid air temperature and humidity are modified by local variation in absorbed solar radiation and the partitioning of sensible and latent heat. The model uses a reference grid site for time series meteorological data and the air temperature and humidity of any other grid can be obtained by solving the heat flux network equations. PASATH was coupled with the USDA iTree-Hydro water balance model to obtain evapotranspiration terms and run from 20 to 29 August 2010 at a 360 m by 360 m grid scale and hourly time step across a 285 km2 watershed including the urban area of Syracuse, NY. PASATH predictions were tested at nine urban weather stations representing variability in urban topography and land cover. The PASATH model predictive efficiency R2 ranged from 0.81 to 0.99 for air temperature and 0.77 to 0.97 for dew point temperature. PASATH is expected to have broad applications on environmental and ecological models.

  7. Microwave soil moisture estimation in humid and semiarid watersheds

    NASA Technical Reports Server (NTRS)

    O'Neill, P. E.; Jackson, T. J.; Chauhan, N. S.; Seyfried, M. S.

    1993-01-01

    Land surface hydrologic-atmospheric interactions in humid and semi-arid watersheds were investigated. Active and passive microwave sensors were used to estimate the spatial and temporal distribution of soil moisture at the catchment scale in four areas. Results are presented and discussed. The eventual use of this information in the analysis and prediction of associated hydrologic processes is examined.

  8. Evaluation of hair humidity resistance/moisturization from hair elasticity.

    PubMed

    Gao, Timothy

    2007-01-01

    Average water regain and hair elasticity (Young's modulus) of virgin dark brown and bleached hair fibers under different relative humidity (RH) were determined. It is observed that hair water regain increases linearly with an increase in RH in the range of 40-85%; and the remaining percent of hair elasticity decreases linearly with an increase in RH in the range of 50-80%. Therefore, measurements of average hair elasticity at 50% and 80% RH, respectively, under various equilibrium times before and after cosmetic treatments can be used to evaluate effects of cosmetic treatments on water adsorption behavior of hair-improvement in hair humidity resistance or enhancement in hair moisture uptake. A Hair Humidity Resistance Factor (H(2)RF) has been defined. If R(2)HF > 1, the product improves hair humidity resistance-anti-frizz; if R(2)HF < 1, the product enhances hair water adsorption; when R(2)HF approximately 1, the product has no significant effect on hair water adsorption behavior. This method was applied to evaluate anti-frizz performance of several shampoo formulations containing Polyquaternium-10, or Polyquaternium-70, or Polyquaternium-67, or Guar Hydroxypropyltrimonium Chloride. It was found PQ-70 shampoo showed the highest H(2)RF value and the best anti-frizz performance among these tested shampoos. The results were consistent with those obtained from Image Analysis. PMID:17728940

  9. Design of a Humidity Sensor Tag for Passive Wireless Applications

    PubMed Central

    Wu, Xiang; Deng, Fangming; Hao, Yong; Fu, Zhihui; Zhang, Lihua

    2015-01-01

    This paper presents a wireless humidity sensor tag for low-cost and low-power applications. The proposed humidity sensor tag, based on radio frequency identification (RFID) technology, was fabricated in a standard 0.18 μm complementary metal oxide semiconductor (CMOS) process. The top metal layer was deposited to form the interdigitated electrodes, which were then filled with polyimide as the humidity sensing layer. A two-stage rectifier adopts a dynamic bias-voltage generator to boost the effective gate-source voltage of the switches in differential-drive architecture, resulting in a flat power conversion efficiency curve. The capacitive sensor interface, based on phase-locked loop (PLL) theory, employs a simple architecture and can work with 0.5 V supply voltage. The measurement results show that humidity sensor tag achieves excellent linearity, hysteresis and stability performance. The total power-dissipation of the sensor tag is 2.5 μW, resulting in a maximum operating distance of 23 m under 4 W of radiation power of the RFID reader. PMID:26457707

  10. Design of a Humidity Sensor Tag for Passive Wireless Applications.

    PubMed

    Wu, Xiang; Deng, Fangming; Hao, Yong; Fu, Zhihui; Zhang, Lihua

    2015-01-01

    This paper presents a wireless humidity sensor tag for low-cost and low-power applications. The proposed humidity sensor tag, based on radio frequency identification (RFID) technology, was fabricated in a standard 0.18 μm complementary metal oxide semiconductor (CMOS) process. The top metal layer was deposited to form the interdigitated electrodes, which were then filled with polyimide as the humidity sensing layer. A two-stage rectifier adopts a dynamic bias-voltage generator to boost the effective gate-source voltage of the switches in differential-drive architecture, resulting in a flat power conversion efficiency curve. The capacitive sensor interface, based on phase-locked loop (PLL) theory, employs a simple architecture and can work with 0.5 V supply voltage. The measurement results show that humidity sensor tag achieves excellent linearity, hysteresis and stability performance. The total power-dissipation of the sensor tag is 2.5 μW, resulting in a maximum operating distance of 23 m under 4 W of radiation power of the RFID reader. PMID:26457707

  11. Stable and Selective Humidity Sensing Using Stacked Black Phosphorus Flakes.

    PubMed

    Yasaei, Poya; Behranginia, Amirhossein; Foroozan, Tara; Asadi, Mohammad; Kim, Kibum; Khalili-Araghi, Fatemeh; Salehi-Khojin, Amin

    2015-10-27

    Black phosphorus (BP) atomic layers are known to undergo chemical degradation in humid air. Yet in more robust configurations such as films, composites, and embedded structures, BP can potentially be utilized in a large number of practical applications. In this study, we explored the sensing characteristics of BP films and observed an ultrasensitive and selective response toward humid air with a trace-level detection capability and a very minor drift over time. Our experiments show that the drain current of the BP sensor increases by ∼4 orders of magnitude as the relative humidity (RH) varies from 10% to 85%, which ranks it among the highest ever reported values for humidity detection. The mechanistic studies indicate that the operation principle of the BP film sensors is based on the modulation in the leakage ionic current caused by autoionization of water molecules and ionic solvation of the phosphorus oxoacids produced on moist BP surfaces. Our stability tests reveal that the response of the BP film sensors remains nearly unchanged after prolonged exposures (up to 3 months) to ambient conditions. This study opens up the route for utilizing BP stacked films in many potential applications such as energy generation/storage systems, electrocatalysis, and chemical/biosensing. PMID:26401950

  12. Whey protein concentrate storage at elevated temperature and humidity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dairy processors are finding new export markets for whey protein concentrate (WPC), a byproduct of cheesemaking, but they need to know if full-sized bags of this powder will withstand high temperature and relative humidity (RH) levels during unrefrigerated storage under tropical conditions. To answ...

  13. Irrigation scheduling based on crop canopy temperature for humid environments

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The use of infrared thermometers (IR) to measure canopy temperatures for irrigation scheduling has been successfully applied in arid environments. Functionality of this technique in humid areas has been limited due to the presence of low vapor pressure deficits (VPD) and intermittent cloud cover. T...

  14. Humidity Sensors Principle, Mechanism, and Fabrication Technologies: A Comprehensive Review

    PubMed Central

    Farahani, Hamid; Wagiran, Rahman; Hamidon, Mohd Nizar

    2014-01-01

    Humidity measurement is one of the most significant issues in various areas of applications such as instrumentation, automated systems, agriculture, climatology and GIS. Numerous sorts of humidity sensors fabricated and developed for industrial and laboratory applications are reviewed and presented in this article. The survey frequently concentrates on the RH sensors based upon their organic and inorganic functional materials, e.g., porous ceramics (semiconductors), polymers, ceramic/polymer and electrolytes, as well as conduction mechanism and fabrication technologies. A significant aim of this review is to provide a distinct categorization pursuant to state of the art humidity sensor types, principles of work, sensing substances, transduction mechanisms, and production technologies. Furthermore, performance characteristics of the different humidity sensors such as electrical and statistical data will be detailed and gives an added value to the report. By comparison of overall prospects of the sensors it was revealed that there are still drawbacks as to efficiency of sensing elements and conduction values. The flexibility offered by thick film and thin film processes either in the preparation of materials or in the choice of shape and size of the sensor structure provides advantages over other technologies. These ceramic sensors show faster response than other types. PMID:24784036

  15. 40 CFR 86.344-79 - Humidity calculations.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 18 2011-07-01 2011-07-01 false Humidity calculations. 86.344-79 Section 86.344-79 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF EMISSIONS FROM NEW AND IN-USE HIGHWAY VEHICLES AND ENGINES Emission Regulations for New Gasoline-Fueled and...

  16. Diurnal variation of tropospheric relative humidity in tropical regions

    NASA Astrophysics Data System (ADS)

    Moradi, Isaac; Arkin, Philip; Ferraro, Ralph; Eriksson, Patrick; Fetzer, Eric

    2016-06-01

    Despite the importance of water vapor especially in the tropical region, the diurnal variations of water vapor have not been completely investigated in the past due to the lack of adequate observations. Measurements from Sondeur Atmosphérique du Profil d'Humidité Intertropicale par Radiométrie (SAPHIR) onboard the low inclination Megha-Tropiques satellite with frequent daily revisits provide a valuable dataset for investigating the diurnal and spatial variation of tropospheric relative humidity in the tropical region. In this study, we first transformed SAPHIR observations into layer-averaged relative humidity, then partitioned the data based on local observation time into 24 bins with a grid resolution of one degree. Afterwards, we fitted Fourier series to the binned data. Finally, the mean, amplitude, and diurnal peak time of relative humidity in tropical regions were calculated for each grid point using either the measurements or Fourier series. The results were separately investigated for different SAPHIR channels as well as for relative humidity with respect to both liquid and ice phases. The results showed that the wet and dry regions are, respectively, associated with convective and subsidence regions which is consistent with the previous studies. The mean tropospheric humidity values reported in this study are generally 10 to 15 % higher than those reported using infrared observations which is because of strict cloud screening for infrared measurements. The results showed a large inhomogeneity in diurnal variation of tropospheric relative humidity in tropical region. The diurnal amplitude was larger over land than over ocean and the oceanic amplitude was larger over convective regions than over subsidence regions. The results showed that the diurnal amplitude is less than 10 % in middle and upper troposphere, but it is up to 30 % in lower troposphere over land. Although the peak of RH generally occurs over night or in early morning, there are several

  17. "You Must Know Where You Come From": South African Youths' Perceptions of Religion in Time of Social Change

    ERIC Educational Resources Information Center

    Brittian, Aerika S.; Lewin, Nina; Norris, Shane A.

    2013-01-01

    This study examined South African youths' perceptions of religion during a period of social and economic transition. In-depth interviews were conducted with 55 Black South African youth (age 18) living in the Johannesburg-Soweto metropolitan area. Data were analyzed in a manner consistent with grounded theory methodology and structural…

  18. Predictors of Outcomes for African Americans in a Rehabilitation State Agency: Implications for National Policy and Practice

    ERIC Educational Resources Information Center

    Balcazar, Fabricio E.; Oberoi, Ashmeet K.; Suarez-Balcazar, Yolanda; Alvarado, Francisco

    2012-01-01

    A review of vocational rehabilitation (VR) data from a Midwestern state was conducted to identify predictors of rehabilitation outcomes for African American consumers. The database included 37,404 African Americans who were referred or self-referred over a period of five years. Logistic regression analysis indicated that except for age and…

  19. Overcoming the Odds: The Association between Location, Preparation, and Financial Obligation on Graduation Rates of African American College Students

    ERIC Educational Resources Information Center

    Rush-Shumpert, Paula J.

    2013-01-01

    The purpose of this study was to understand why graduation rates of African American male students from four-year historically Black colleges and universities (HBCUs) within a six-year period were not on par with those of other races and ethnicities and, in particular, whether the reasons African American male students drop out rather than persist…

  20. African swine fever.

    PubMed

    Penrith, Mary-Louise

    2009-03-01

    African swine fever (ASF) is a devastating haemorrhagic fever of pigs that causes up to 100% mortality, for which there is no vaccine. It is caused by a unique DNA virus that is maintained in an ancient cycle between warthogs and argasid ticks, making it the only known DNA arbovirus. ASF has a high potential for transboundary spread, and has twice been transported from Africa to other continents--Europe and subsequently the Caribbean and Brazil (1957, 1959) and the Caucasus (2007). It is also a devastating constraint for pig production in Africa. Research at Onderstepoort Veterinary Institute has made and is making important contributions to knowledge of this disease, focusing on the cycle in warthogs and tampans and transmission from that cycle to domestic pigs, resistance to its effects in domestic pigs, and the molecular genetic characterisation and epidemiology of the virus. PMID:19967933

  1. The African Millennium Villages

    PubMed Central

    Sanchez, Pedro; Palm, Cheryl; Sachs, Jeffrey; Denning, Glenn; Flor, Rafael; Harawa, Rebbie; Jama, Bashir; Kiflemariam, Tsegazeab; Konecky, Bronwen; Kozar, Raffaela; Lelerai, Eliud; Malik, Alia; Modi, Vijay; Mutuo, Patrick; Niang, Amadou; Okoth, Herine; Place, Frank; Sachs, Sonia Ehrlich; Said, Amir; Siriri, David; Teklehaimanot, Awash; Wang, Karen; Wangila, Justine; Zamba, Colleen

    2007-01-01

    We describe the concept, strategy, and initial results of the Millennium Villages Project and implications regarding sustainability and scalability. Our underlying hypothesis is that the interacting crises of agriculture, health, and infrastructure in rural Africa can be overcome through targeted public-sector investments to raise rural productivity and, thereby, to increased private-sector saving and investments. This is carried out by empowering impoverished communities with science-based interventions. Seventy-eight Millennium Villages have been initiated in 12 sites in 10 African countries, each representing a major agroecological zone. In early results, the research villages in Kenya, Ethiopia, and Malawi have reduced malaria prevalence, met caloric requirements, generated crop surpluses, enabled school feeding programs, and provided cash earnings for farm families. PMID:17942701

  2. Larger genetic differences within africans than between Africans and Eurasians.

    PubMed Central

    Yu, Ning; Chen, Feng-Chi; Ota, Satoshi; Jorde, Lynn B; Pamilo, Pekka; Patthy, Laszlo; Ramsay, Michele; Jenkins, Trefor; Shyue, Song-Kun; Li, Wen-Hsiung

    2002-01-01

    The worldwide pattern of single nucleotide polymorphism (SNP) variation is of great interest to human geneticists, population geneticists, and evolutionists, but remains incompletely understood. We studied the pattern in noncoding regions, because they are less affected by natural selection than are coding regions. Thus, it can reflect better the history of human evolution and can serve as a baseline for understanding the maintenance of SNPs in human populations. We sequenced 50 noncoding DNA segments each approximately 500 bp long in 10 Africans, 10 Europeans, and 10 Asians. An analysis of the data suggests that the sampling scheme is adequate for our purpose. The average nucleotide diversity (pi) for the 50 segments is only 0.061% +/- 0.010% among Asians and 0.064% +/- 0.011% among Europeans but almost twice as high (0.115% +/- 0.016%) among Africans. The African diversity estimate is even higher than that between Africans and Eurasians (0.096% +/- 0.012%). From available data for noncoding autosomal regions (total length = 47,038 bp) and X-linked regions (47,421 bp), we estimated the pi-values for autosomal regions to be 0.105, 0.070, 0.069, and 0.097% for Africans, Asians, Europeans, and between Africans and Eurasians, and the corresponding values for X-linked regions to be 0.088, 0.042, 0.053, and 0.082%. Thus, Africans differ from one another slightly more than from Eurasians, and the genetic diversity in Eurasians is largely a subset of that in Africans, supporting the out of Africa model of human evolution. Clearly, one must specify the geographic origins of the individuals sampled when studying pi or SNP density. PMID:12019240

  3. [West African childbirth traditions].

    PubMed

    Hallgren, R

    1983-11-01

    Religious and medical practices are steeped in the traditions of West African culture vis-a-vis childbirth. It is customary for delivery to occur with the woman squatting on the ground surrounded by sisters and female relatives, some of whom function as midwives. Midwives get paid only if delivery is successful. A stool is also often used in childbirth. The name given to a child in the Yoruba tribe in Nigeria has to refer to the circumstances of the individual's birth. The contact with the earth (as in the squatting position) has religious overtones--it indicates the fecundity of the earth, and the mother's contact with it. Infertility is considered the greatest tragedy in traditional African society. In Senegal, a childless woman pays a fertile one a certain sum in return for bearing her a child who would be raised as her own (this tradition is not unlike surrogate motherhood in Western countries). Men are never present at birth; however, in urban settings this practice is changing. The burial of the placenta and umbilical cord is thought to restore the woman's fertility and help heal her womb. This practice was even recorded in 19th century Sweden harkening back to heathen times. In Ghana, an infertile woman urinates on the ground where the placenta is buried in the belief that her fertility will be restored. The birth of twins is regarded as a great blessing, and as a sign of fertility; however, the inability of the mother to breast-feed both twins may result in the death of the weaker child. The harmony of nature, animals, and human beings is paramount in traditional West Africa religion and life, and undoubtedly Western culture could learn from some of these beliefs. PMID:6558064

  4. Cattle ticks in Cameroon: is Rhipicephalus (Boophilus) microplus absent in Cameroon and the Central African region?

    PubMed

    Awa, D N; Adakal, H; Luogbou, N D D; Wachong, K H; Leinyuy, I; Achukwi, M D

    2015-03-01

    In most parts of the world, ticks are rapidly developing resistance to commonly used acaricides thus rendering control difficult. This constraint is further compounded by the introduction of new species in areas where they did not exist before. Such is the case with the introduction into and rapid spread of Rhipicephalus (Boophilus) microplus in some countries of West Africa. With the looming threat of its further spread in the region, the objective of the present study was to update knowledge on cattle ticks in Cameroon. Among 19,189 ticks collected monthly from 60 animals in 5 herds from March 2012 to February 2013, Rh. (B.) decoloratus was the most abundant species with a relative prevalence of 62.2%, followed by Amblyomma variegatum (28.4%), Rh. (B.) annulatus (0.2%), Rh. (B.) geigyi (0.03%), other Rhipicephalus spp. (8.4%) and Hyalomma spp. (0.3%). Rh. (B.) decoloratus and A. variegatum were also the most widely distributed in space. Infestation rate was generally high, with average tick count/animal of about 80 during peak periods. Tick distribution and abundance in the different sites was as varied as the underlying factors, among which the most important were management systems and climatic factors. The effects of rainfall and temperature were confounded by other factors and difficult to evaluate. However, it appears tick development depends among other factors, on a humidity threshold, above which there is not much more effect. Rh. microplus was not found during this study, but more extensive tick collections have to be done to confirm this. In conclusion, cattle tick infestation in Cameroon remains an important cause for concern. Farmers need assistance in the use and management of acaricides in order to increase their efficiency and reduce the development of resistance. Although Rh. microplus was not found, its introduction from other West African countries is imminent if adequate measures, especially in the control and limitation of animal movements

  5. Skill, reproducibility and potential predictability of the West African monsoon in coupled GCMs

    NASA Astrophysics Data System (ADS)

    Philippon, N.; Doblas-Reyes, F. J.; Ruti, P. M.

    2010-07-01

    In the framework of the ENSEMBLES FP6 project, an ensemble prediction system based on five different state-of-the-art European coupled models has been developed. This study evaluates the performance of these models for forecasting the West African monsoon (WAM) at the monthly time scale. From simulations started the 1 May of each year and covering the period 1991-2001, the reproducibility and potential predictability (PP) of key parameters of the WAM—rainfall, zonal and meridional wind at four levels from the surface to 200 hPa, and specific humidity, from July to September—are assessed. The Sahelian rainfall mode of variability is not accurately reproduced contrary to the Guinean rainfall one: the correlation between observations (from CMAP) and the multi-model ensemble mean is 0.17 and 0.55, respectively. For the Sahelian mode, the correlation is consistent with a low PP of about ~6%. The PP of the Guinean mode is higher, ~44% suggesting a stronger forcing of the sea surface temperature on rainfall variability over this region. Parameters relative to the atmospheric dynamics are on average much more skillful and reproducible than rainfall. Among them, the first mode of variability of the zonal wind at 200 hPa that depicts the Tropical Easterly Jet, is correlated at 0.79 with its “observed” counterpart (from the NCEP/DOE2 reanalyses) and has a PP of 39%. Moreover, models reproduce the correlations between all the atmospheric dynamics parameters and the Sahelian rainfall in a satisfactory way. In that context, a statistical adaptation of the atmospheric dynamic forecasts, using a linear regression model with the leading principal components of the atmospheric dynamical parameters studied, leads to moderate receiver operating characteristic area under the curve and correlation skill scores for the Sahelian rainfall. These scores are however much higher than those obtained using the modelled rainfall.

  6. Evaluation of the capability of RegCM4.0 in simulating East African climate

    NASA Astrophysics Data System (ADS)

    Ogwang, Bob Alex; Chen, Haishan; Li, Xing; Gao, Chujie

    2016-04-01

    The International Centre for Theoretical Physics (ICTP) regional climate model RegCM4.0 is used in this study to examine its ability to reproduce the climate of East Africa (EA) in regard to the annual cycle and June-to-August (JJA) seasonal climatology. Two domain sizes [large domain (LD) and small domain (SD)] and two cumulus convection schemes [Grell convection scheme with Fritsch-Chappell closure assumption (GRE scheme) and MIT scheme (EMA scheme)] are used. Simulations were done for the period 1989-2008 at a resolution of 50 km. The experiments were performed with the initial and lateral boundary conditions obtained from ERA-Interim-gridded reanalysis data at a 1.5° resolution. The variables investigated are precipitation, temperature, humidity, diurnal temperature range, and 850-hPa winds. Results show that the model realistically reproduces the East African climate, with a few discrepancies due to the different cumulus convection schemes and the domain sizes used. Grell with Fritsch-Chappell (Grell-FC) scheme captures well the observed climate in regard to the annual cycle and June-to-August seasonal climatology, with a tendency to underestimate rainfall over the JJA rainfall maximum region (RMR). This scheme performs better in LD than in SD. EMA scheme similarly captures well the observed climatology. It tends to overestimate rainfall over RMR. It however performs better in SD than in LD. The ensemble mean of simulations with GRE and EMA schemes (ENSM) tends to offer an improved representation of the observed climate, with a few discrepancies owing to the individual schemes used. In general, therefore, considering the performance of the model in both domains, the East African climate based on this study is better simulated by the Grell-FC scheme over LD. The observed biases in this study signify that the ability of the model in simulating climate over East Africa is still a significant challenge. Thus, future work must focus on improving the performance of

  7. High resolution vertical profiles of wind, temperature and humidity obtained by computer processing and digital filtering of radiosonde and radar tracking data from the ITCZ experiment of 1977

    NASA Technical Reports Server (NTRS)

    Danielson, E. F.; Hipskind, R. S.; Gaines, S. E.

    1980-01-01

    Results are presented from computer processing and digital filtering of radiosonde and radar tracking data obtained during the ITCZ experiment when coordinated measurements were taken daily over a 16 day period across the Panama Canal Zone. The temperature relative humidity and wind velocity profiles are discussed.

  8. Highly Sensitive and Fast Response Colorimetric Humidity Sensors Based on Graphene Oxides Film.

    PubMed

    Chi, Hong; Liu, Yan Jun; Wang, FuKe; He, Chaobin

    2015-09-16

    Uniform graphene oxide (GO) film for optical humidity sensing was fabricated by dip-coating technique. The resulting GO thin film shows linear optical shifts in the visible range with increase of humidity in the whole relative humidity range (from dry state to 98%). Moreover, GO films exhibit ultrafast sensing to moisture within 250 ms because of the unique atomic thinness and superpermeability of GO sheets. The humidity sensing mechanism was investigated using XRD and computer simulation. The ultrasensitive humidity colorimetric properties of GOs film may enable many potential applications such as disposable humidity sensors for packaging, health, and environmental monitoring. PMID:26305842

  9. Early African Hominids: Pedagogic Patterns.

    ERIC Educational Resources Information Center

    Newman, James L.

    1984-01-01

    By studying early African hominids, students can learn about the interactive testing and creative aspects of scientific thinking and sharpen their geographical skills. It is impossible to study this topic without giving prominence to space and time. (RM)

  10. Effects of temperature and humidity cycling on the strengths of textile reinforced carbon/epoxy composite materials

    NASA Technical Reports Server (NTRS)

    Cano, Roberto J.; Furrow, Keith W.

    1993-01-01

    Results are presented from an experimental evaluation of the combined effects of temperature and humidity cycling on AS4/3501-6 composites (unstitched, Kevlar 29 stitched, and S-2 glass stitched uniweave fabric) and AS4/E905L composites (2-D, S-2 glass stitched 2-D, and 3-D braided fabric). The AS4/3501-6 uniweave material had a quasi-isotropic layup, whereas the AS4/E905L materials were braided in a (+/-30 deg/0 deg)(sub s) orientation. Data presented include compression strengths and compression-compression fatigue results for uncycled composites and cycled composites (160, 480, 720, and 1280 cycles from 140 deg F at 95 percent relative humidity to -67 deg F). To observe the presence of microcracking within the laminates, photomicrographs were taken of each material type at the end of each cycling period. Microcracks were found to be more prevalent within stitched laminates, predominantly around individual stitches. The glass stitched laminates showed significant microcracking even before cycling. Less microcracking was evident in the Kevlar stitched materials, whereas the unstitched uniweave material developed microcracks only after cycling. The 3-D braid did not develop microcracks. The static compression strengths of the unstitched and Kevlar stitched uniweave materials were degraded by about 10 percent after 1280 temperature/humidity cycles, whereas the reduction in compression strength for the glass stitched uniweave was less than 3 percent. The reduction in compression strength for the glass stitched 2-D braid was less than 8 percent. The unstitched 2-D and 3-D braids did not lose strength from temperature/humidity cycling. The compression-compression fatigue properties of all six material types were not affected by temperature/humidity cycling.

  11. Improving Comfort in Hot-Humid Climates with a Whole-House Dehumidifier, Windermere, Florida (Fact Sheet)

    SciTech Connect

    Not Available

    2013-11-01

    Maintaining comfort in a home can be challenging in hot-humid climates. At the common summer temperature set point of 75 degrees F, the perceived air temperature can vary by 11 degrees F because higher indoor humidity reduces comfort. Often the air conditioner (AC) thermostat set point is lower than the desirable cooling level to try to increase moisture removal so that the interior air is not humid or "muggy." However, this method is not always effective in maintaining indoor relative humidity (RH) or comfort. In order to quantify the performance of a combined whole-house dehumidifier (WHD) AC system, researchers from the U.S. Department of Energy's Building America team Consortium of Advanced Residential Buildings (CARB) monitored the operation of two Lennox AC systems coupled with a Honeywell DH150 TrueDRY whole-house dehumidifier for a six-month period. By using a WHD to control moisture levels (latent cooling) and optimizing a central AC to control temperature (sensible cooling), improvements in comfort can be achieved while reducing utility costs. Indoor comfort for this study was defined as maintaining indoor conditions at below 60% RH and a humidity ratio of 0.012 lbm/lbm while at common dry bulb set point temperatures of 74 degrees -80 degrees F. In addition to enhanced comfort, controlling moisture to these levels can reduce the risk of other potential issues such as mold growth, pests, and building component degradation. Because a standard AC must also reduce dry bulb air temperature in order to remove moisture, a WHD is typically needed to support these latent loads when sensible heat removal is not desired.

  12. Instrument uncertainty effect on calculation of absolute humidity using dewpoint, wet-bulb, and relative humidity sensors

    SciTech Connect

    Slayzak, S.J.; Ryan, J.P.

    1998-04-01

    As part of the US Department of Energy`s Advanced Desiccant Technology Program, the National Renewable Energy Laboratory (NREL) is characterizing the state-of-the-art in desiccant dehumidifiers, the key component of desiccant cooling systems. The experimental data will provide industry and end users with independent performance evaluation and help researchers assess the energy savings potential of the technology. Accurate determination of humidity ratio is critical to this work and an understanding of the capabilities of the available instrumentation is central to its proper application. This paper compares the minimum theoretical random error in humidity ratio calculation for three common measurement methods to give a sense of the relative maximum accuracy possible for each method assuming systematic errors can be made negligible. A series of experiments conducted also illustrate the capabilities of relative humidity sensors as compared to dewpoint sensors in measuring the grain depression of desiccant dehumidifiers. These tests support the results of the uncertainty analysis. At generally available instrument accuracies, uncertainty in calculated humidity ratio for dewpoint sensors is determined to be constant at approximately 2%. Wet-bulb sensors range between 2% and 6% above 10 g/kg (4%--15% below), and relative humidity sensors vary between 4% above 90% rh and 15% at 20% rh. Below 20% rh, uncertainty for rh sensors increases dramatically. Highest currently attainable accuracies bring dewpoint instruments down to 1% uncertainty, wet bulb to a range of 1%--3% above 10 g/kg (1.5%--8% below), and rh sensors between 1% and 5%.

  13. Seasonal changes in humidity impact drought resistance in tropical Drosophila leontia: testing developmental effects of thermal versus humidity changes.

    PubMed

    Parkash, Ravi; Ranga, Poonam

    2014-03-01

    Drosophila leontia is native to highly humid equatorial tropical habitats but its desiccation sensitivity (~10h) is not consistent with its abundance during the drier autumn season in the subtropical regions. We have tested the effects of developmental acclimation on desiccation resistance and water balance related traits of D. leontia collected during rainy and autumn seasons. The isofemale lines of seasonal populations were reared under ecologically relevant growth temperatures (18 or 26 °C) or humidity conditions (35 or 85% RH) but tested at different times under identical experimental conditions. The larvae as well as flies reared under two thermal conditions (18 or 26 °C) showed no effect on desiccation related traits as well as storage and utilization of energy metabolites. In contrast, for D. leontia reared under low humidity (35% RH), significant changes at larval as well adult stages include increase in the desiccation resistance as well as cuticular lipid quantity, reduced levels of rate of body water loss, higher storage of carbohydrates but lower rate of utilization of carbohydrates as compared with flies reared at high humidity (85% RH). D. leontia has responded to rearing under low humidity conditions by increasing its desiccation resistance but not due to changes in the growth temperatures. These laboratory observations on seasonal populations highlight differences due to rearing conditions but not due to seasons. Further, direct analysis of wild-caught seasonal populations has shown trends similar to developmental acclimation effects. For wild caught flies, there are significant seasonal differences i.e. higher desiccation resistance as well as cuticular lipid quantity but reduced rate of water loss for autumn than rainy season flies. Thus, our laboratory observations are relevant for understanding seasonal adaptations of natural populations of tropical D. leontia to wet-dry conditions in the wild. PMID:24345458

  14. North African savanna fires and atmospheric carbon dioxide

    SciTech Connect

    Iacobellis, S.F.; Frouni, Razafimpaniolo, H.

    1994-04-20

    The effect of north African savanna fires on atmospheric CO{sub 2} is investigated using a tracer transport model. The model uses winds from operational numerical weather prediction analyses and provides CO{sub 2} concentrations as a function of space and time. After a spin-up period of several years, biomass-burning sources are added, and model experiments are run for an additional year, utilizing various estimates of CO{sub 2} sources. The various model experiments show that biomass burning in the north African savannas significantly affects CO{sub 2} concentrations in South America. The effect is more pronounced during the period from January through March, when biomass burning in South America is almost nonexistent. During this period, atmospheric CO{sub 2} concentrations in parts of South America typically may increase by 0.5 to 0.75 ppm at 970 mbar, the average pressure of the lowest model layer. These figures are above the probable uncertainty level, as model runs with biomass-burning sources estimated from independent studies using distinct data sets and techniques indicate. From May through September, when severe biomass burning occurs in South America, the effect of north African savanna fires over South America has become generally small at 970 mbar, but north of the equator it may be of the same magnitude or larger than the effect of South American fires. The CO{sub 2} concentration increase in the extreme northern and southern portions of South America, however, is mostly due to southern African fires, whose effect may be 2-3 times larger than the effect of South American fires at 970 mbar. Even in the central part of the continent, where local biomass-burning emissions are maximum, southern African fires contribute to at least 15% of the CO{sub 2} concentration increase at 970 mbar. 20 refs., 15 figs., 1 tab.

  15. Humidity: A review and primer on atmospheric moisture and human health.

    PubMed

    Davis, Robert E; McGregor, Glenn R; Enfield, Kyle B

    2016-01-01

    Research examining associations between weather and human health frequently includes the effects of atmospheric humidity. A large number of humidity variables have been developed for numerous purposes, but little guidance is available to health researchers regarding appropriate variable selection. We examine a suite of commonly used humidity variables and summarize both the medical and biometeorological literature on associations between humidity and human health. As an example of the importance of humidity variable selection, we correlate numerous hourly humidity variables to daily respiratory syncytial virus isolates in Singapore from 1992 to 1994. Most water-vapor mass based variables (specific humidity, absolute humidity, mixing ratio, dewpoint temperature, vapor pressure) exhibit comparable correlations. Variables that include a thermal component (relative humidity, dewpoint depression, saturation vapor pressure) exhibit strong diurnality and seasonality. Humidity variable selection must be dictated by the underlying research question. Despite being the most commonly used humidity variable, relative humidity should be used sparingly and avoided in cases when the proximity to saturation is not medically relevant. Care must be taken in averaging certain humidity variables daily or seasonally to avoid statistical biasing associated with variables that are inherently diurnal through their relationship to temperature. PMID:26599589

  16. Assimilation of humidity and temperature observations retrieved from ground-based microwave radiometers into a convective-scale NWP model

    NASA Astrophysics Data System (ADS)

    Caumont, Olivier; Vincendon, Béatrice; Cimini, Domenico; Löhnert, Ulrich; Alados-Arboledas, Lucas; Bleisch, René; Buffa, Franco; Enrico Ferrario, Massimo; Haefele, Alexander; Huet, Thierry; Madonna, Fabio; Pace, Giandomenico

    2016-04-01

    Temperature and humidity retrievals from an international network of ground-based microwave radiometers (MWR) have been collected to assess the potential of their assimilation into a convective-scale Numerical Weather Prediction (NWP) system. Thirteen stations over a domain encompassing the western Mediterranean basin were considered for a time period of forty-one days in autumn, when heavy-precipitation events most often plague this area. Prior to their assimilation, MWR data were compared to very-short-term forecasts. Observation-minus-background statistics revealed some biases, but standard deviations were comparable to that obtained with radiosondes. The MWR data were then assimilated in a three-dimensional variational (3DVar) data assimilation system through the use of a rapid update cycle. A set of sensitivity experiments allowed assessing extensively the impact of the assimilation of temperature and humidity profiles, both separately and jointly. The respective benefit of MWR data and radiosonde data on analyses and forecasts was also investigated.

  17. Effect of High-Humidity Testing on Material Parameters of Flexible Printed Circuit Board Materials

    NASA Astrophysics Data System (ADS)

    Lahokallio, Sanna; Saarinen, Kirsi; Frisk, Laura

    2013-09-01

    The tendency of polymers to absorb moisture impairs especially their electrical and mechanical properties. These are important characteristics for printed circuit board (PCB) materials, which should provide mechanical support as well as electrical insulation in many different environments in order to guarantee safe operation for electrical devices. Moreover, the effects of moisture are accelerated at increased temperatures. In this study, three flexible PCB dielectric materials, namely polyimide (PI), fluorinated ethylene-propylene (FEP), and polyethylene terephthalate (PET), were aged over different periods of time in a high-humidity test, in which the temperature was 85°C and relative humidity 85%. After aging, the changes in the structure of the polymers were studied by determining different material parameters such as modulus of elasticity, glass-transition temperature, melting point, coefficient of thermal expansion, water absorption, and crystallinity, and changes in the chemical structure with several techniques including thermomechanical analysis, differential scanning calorimetry, Fourier-transform infrared spectroscopy, moisture analysis, and a precision scale. The results showed that PI was extremely stable under the aging conditions and therefore an excellent choice for electrical applications under harsh conditions. Similarly, FEP proved to be relatively stable under the applied aging conditions. However, its crystallinity increased markedly during aging, and after 6000 h of aging the results indicated oxidation. PET suffered from hydrolysis during the test, leading to its embrittlement after 2000 h of aging.

  18. Surface soil humidity retrieval using remote sensing techniques: a triangle method validation

    NASA Astrophysics Data System (ADS)

    Maltese, Antonino; Cammalleri, Carmelo; Capodici, Fulvio; Ciraolo, Giuseppe; La Loggia, Goffredo

    2010-10-01

    Soil humidity plays a key-role in hydrological and agricultural processes. In the rainfall-runoff processes the knowledge of its spatial distribution is fundamental to accurately model these phenomena. Furthermore in agronomy and agricultural sciences, assessing the water content of the root zone is required in order to optimize the plant productivity and to improve the irrigation systems management. Despite the importance of this variable the in situ measurements techniques based on Time Domain Reflectometry (TDR) or on the standard thermo-gravimetric methods, are neither cost-effective nor representative of its spatial and temporal variability. Indirect estimations via Earth Observation (EO) images include the triangle method, which shows that Land Surface Temperature (LST) is prevalently controlled by surface and root zone humidity in bare and vegetated soils respectively. The effects of pre-processing techniques correcting for altimetry and seasonality are analyzed by means of shortwave and longwave airborne images acquired on a vineyard during a whole phenological period. The paper also discusses the advantages induced by replacing the absolute temperatures with relative values, that were obtained subtracting the temperatures measured by micrometeorological station or the surface temperature of high thermal inertia surfaces (as small irrigation reservoir) chosen as reference values. The validation with in situ data also highlights that a higher spatial resolution not necessarily imply a higher accuracy.

  19. Effect of air temperature and humidity on ingestive behaviour of sheep

    NASA Astrophysics Data System (ADS)

    Paranhos da Costa, Mateus J. R.; da Silva, Roberto Gomes; de Souza, Roberto Carlos

    1992-12-01

    Thirty-two Polwarth ewes, of ages up to 1 year, were observed in a climatic chamber (24 to 45° C) for eight periods of 5 h each. The observations were made through a window in the chamber wall. All animals were observed four times, then shorn and observed four times again. The animals were given weighed quantities of water and feed consisting of commercial concentrate plus Rhodes grass ( Chloris gayana) hay. The water and feed remaining after 5 h of observation were weighed. The following traits were analysed: time eating hay (TEH), time eating concentrate (TEC), time drinking water (TDW), weight of hay eaten (WHE), weight of concentrate eaten (WCE), volume of ingested water (VIW), ruminating time standing up (RTS), ruminating time lying down (RTL), idling time standing up (ITS), and idling time lying down (ITL). Shearing had a significant effect for all traits except ITS. Shearing resulted in higher values for all traits except for ITS and ITL. Ingestion of hay (TEH and WHE) decreased with increased air temperature and humidity, while the ingestion of concentrate (TEC) and WHE) and water (TDW and VIW) increased. Rumination decreased with increased air temperature and humidity, and was higher in shorn than in unshorn sheep.

  20. The influence of relative humidity on iron corrosion under proton irradiation

    NASA Astrophysics Data System (ADS)

    Lapuerta, S.; Bérerd, N.; Moncoffre, N.; Millard-Pinard, N.; Jaffrézic, H.; Crusset, D.; Féron, D.

    2008-03-01

    With regard to the storage for high-level radioactive waste and the reversible period of a geological repository, the influence of proton irradiation on the indoor atmospheric corrosion of iron has been investigated in relation to the relative humidity (RH) in the atmosphere. Irradiation experiments were performed using a 3-MeV extracted proton beam. Relative humidity varies from 0% to 85%. Before and after each irradiation, the surfaces of the sample were characterised by Rutherford backscattering spectrometry in order to determine oxygen concentrations in the metal. The maximum oxidation rate was observed for 45% RH in air under proton irradiation and was compared with literature data without irradiation where the maximum oxidation rate was observed at 95% RH. The experimental results are discussed on the basis of the Langmuir-Hinshelwood (LH) model: they are explained by the contrast between the adsorption of O 2 and H 2O species on the active cathodic sites of the iron surface and by the formation of H +(H 2O) n.

  1. Humidity effects on tribochemical removal of GaAs surfaces

    NASA Astrophysics Data System (ADS)

    Yu, Bingjun; Gao, Jian; Jin, Chenning; Xiao, Chen; Wu, Jiang; Liu, Huiyun; Jiang, Shulan; Chen, Lei; Qian, Linmao

    2016-06-01

    Defect-free tribochemical removal of gallium arsenide (GaAs) was demonstrated in vacuum, dry air, and various humidity environments by scratching with a SiO2 tip. The removal depth increases with increasing relative humidity (1–90%), and reaches its maximum value in water. A perfect crystal matrix without defects was observed in the cross section of the scratched groove using a transmission electron microscope. A model based on reactive tip scratching-induced oxidation, water solubility of debris, and adhesion effect was proposed to interpret tribochemical removal of GaAs surface. This study provides new insights into defect-free and site-controlled nanofabrication of GaAs.

  2. Fatigue cracking of aluminum under spectrum loading at various humidities

    NASA Technical Reports Server (NTRS)

    Chappell, D. P.; Nelson, H.

    1985-01-01

    The effect of moisture on Stage I fatigue in aluminum was studied under constant amplitude loading and under a severe log-normal spectrum loading. Crack initiation and early crack growth was monitored using accurate specimen compliance measurements statistically generated using computer-aided data acquisition and analysis. Fatigue strength in aluminum was found to be greatly reduced by humidity under both constant amplitude and log-normal spectrum loading. Use of Miner's theory of cumulative damage to predict the outcome of the spectrum tests, given the results of the constant amplitude tests, was investigated. A systematic pattern of deviation from Miner's theory was found, which was also a function of the humidity level.

  3. Lowered Humidity Produces Human Epidermal Equivalents with Enhanced Barrier Properties

    PubMed Central

    Sun, Richard; Celli, Anna; Crumrine, Debra; Hupe, Melanie; Adame, Lillian C.; Pennypacker, Sally D.; Park, Kyungho; Uchida, Yoshikazu; Feingold, Kenneth R.; Elias, Peter M.; Ilic, Dusko

    2015-01-01

    Multilayered human keratinocyte cultures increasingly are used to model human epidermis. Until now, studies utilizing human epidermal equivalents (HEEs) have been limited because previous preparations do not establish a normal epidermal permeability barrier. In this report, we show that reducing environmental humidity to 50% relative humidity yields HEEs that closely match human postnatal epidermis and have enhanced repair of the permeability barrier. These cultures display low transepidermal water loss and possess a calcium and pH gradient that resembles those seen in human epidermis. These cultures upregulate glucosylceramide synthase and make normal-appearing lipid lamellar bilayers. The epidermal permeability barrier of these cultures can be perturbed, using the identical tools previously described for human skin, and recover in the same time course seen during in vivo barrier recovery. These cultures will be useful for basic and applied studies on epidermal barrier function. PMID:24803151

  4. Flight prototype CO2 and humidity control system

    NASA Technical Reports Server (NTRS)

    Rudy, K. M.

    1979-01-01

    A regenerable CO2 and humidity control system is presently being developed for potential use on shuttle as an alternative to the baseline lithium hydroxide system. The system utilizes a sorbent material (designated HS-C) to adsorb CO2 and the latent heat load from the cabin atmosphere and desorb the CO2 and water vapor overboard when exposed to a space vacuum, thus reducing the overall vehicle heat rejection load. Continuous operation is achieved by utilizing two beds which are alternatively cycled between adsorption and desorption. The HS-C material process was verified. Design concepts for the auxiliary components for the HS-C prototype system were generated. Performance testing verified system effectiveness in controlling CO2 partial pressure and humidity.

  5. A High Temperature Capacitive Humidity Sensor Based on Mesoporous Silica

    PubMed Central

    Wagner, Thorsten; Krotzky, Sören; Weiß, Alexander; Sauerwald, Tilman; Kohl, Claus-Dieter; Roggenbuck, Jan; Tiemann, Michael

    2011-01-01

    Capacitive sensors are the most commonly used devices for the detection of humidity because they are inexpensive and the detection mechanism is very specific for humidity. However, especially for industrial processes, there is a lack of dielectrics that are stable at high temperature (>200 °C) and under harsh conditions. We present a capacitive sensor based on mesoporous silica as the dielectric in a simple sensor design based on pressed silica pellets. Investigation of the structural stability of the porous silica under simulated operating conditions as well as the influence of the pellet production will be shown. Impedance measurements demonstrate the utility of the sensor at both low (90 °C) and high (up to 210 °C) operating temperatures. PMID:22163790

  6. The aging correlation (RH + t): Relative humidity (%) + temperature (deg C)

    NASA Technical Reports Server (NTRS)

    Cuddihy, E. F.

    1986-01-01

    An aging correlation between corrosion lifetime, and relative humidity RH (%) and temperature t (C) has been reported in the literature. This aging correlation is a semi-log plot of corrosion lifetime on the log scale versus the interesting summation term RH(%) + t(C) on the linear scale. This empirical correlation was derived from observation of experimental data trends and has been referred to as an experimental law. Using electrical resistivity data of polyvinyl butyral (PVB) measured as a function of relative humidity and temperature, it was found that the electrical resistivity could be expressed as a function of the term RH(%) t(C). Thus, if corrosion is related to leakage current through an organic insulator, which, in turn, is a function of RH and t, then some partial theoretical validity for the correlation is indicated. This article describes the derivation of the term RH(%) t(C) from PVB electrical resistivity data.

  7. Water-absorbing capacitor system for measuring relative humidity

    NASA Technical Reports Server (NTRS)

    Laue, Eric G. (Inventor)

    1987-01-01

    A method and apparatus using a known water-absorbent polymer as a capacitor which is operated at a dc voltage for measuring relative humidity is presented. When formed as a layer between porous electrically-conductive electrodes and operated in an RC oscillator circuit, the oscillator frequency varies inversely with the partial pressure of the moisture to be measured. In a preferred embodiment, the capacitor is formed from Nafion and is operated at a low dc voltage with a resistor as an RC circuit in an RC oscillator. At the low voltage, the leakage current is proper for oscillation over a satisfactory range. The frequency of oscillation varies in an essentially linear fashion with relative humidity which is represented by the moisture being absorbed into the Nafion. The oscillation frequency is detected by a frequency detector.

  8. Ozone reaction with interior building materials: Influence of diurnal ozone variation, temperature and humidity

    NASA Astrophysics Data System (ADS)

    Rim, Donghyun; Gall, Elliott T.; Maddalena, Randy L.; Nazaroff, William W.

    2016-01-01

    Elevated tropospheric ozone concentrations are associated with increased morbidity and mortality. Indoor ozone chemistry affects human exposure to ozone and reaction products that also may adversely affect health and comfort. Reactive uptake of ozone has been characterized for many building materials; however, scant information is available on how diurnal variation of ambient ozone influences ozone reaction with indoor surfaces. The primary objective of this study is to investigate ozone-surface reactions in response to a diurnally varying ozone exposure for three common building materials: ceiling tile, painted drywall, and carpet tile. A secondary objective is to examine the effects of air temperature and humidity. A third goal is to explore how conditioning of materials in an occupied office building might influence subsequent ozone-surface reactions. Experiments were performed at bench-scale with inlet ozone concentrations varied to simulate daytime (ozone elevated) and nighttime (ozone-free in these experiments) periods. To simulate office conditions, experiments were conducted at two temperatures (22 °C and 28 °C) and three relative humidity values (25%, 50%, 75%). Effects of indoor surface exposures were examined by placing material samples in an occupied office and repeating bench-scale characterization after exposure periods of 1 and 2 months. Deposition velocities were observed to be highest during the initial hour of ozone exposure with slow decrease in the subsequent hours of simulated daytime conditions. Daily-average ozone reaction probabilities for fresh materials are in the respective ranges of (1.7-2.7) × 10-5, (2.8-4.7) × 10-5, and (3.0-4.5) × 10-5 for ceiling tile, painted drywall, and carpet tile. The reaction probability decreases by 7%-47% across the three test materials after two 8-h periods of ozone exposure. Measurements with the samples from an occupied office reveal that deposition velocity can decrease or increase with time

  9. Holographic humidity response of slanted gratings in moisture-absorbing acrylamide photopolymer.

    PubMed

    Yu, Dan; Liu, Hongpeng; Mao, Dongyao; Geng, Yaohui; Wang, Weibo; Sun, Liping; Lv, Jiang

    2015-08-01

    Holographic humidity response is characterized in detail using transmission and reflection geometry in moisture-absorbing acrylamide photopolymer. The diffraction spectrum and its temporal evolution at various relative humidity are measured and analyzed. The quantitative relations between relative humidity and holographic properties of slanted gratings are determined. The responsibility of holographic gratings for various relative humidity is observed by the spectrum response of gratings. The extracted humidity constants reflect the applicability of reflection and transmission gratings at different humidity regions. The humidity reversibility experiment is achieved for confirming repeatability of the sensor. These experiments provide a probability for improving the applicability of a holographic humidity sensor. Finally, the extended diffusion model is derived by introducing the expansion coefficient to describe the dynamic swelling process. This work can accelerate development of the holographic sensor and provide a novel strategy for exploring the swelling mechanism of photopolymer. PMID:26368095

  10. North African savanna fires and atmospheric carbon dioxide

    NASA Technical Reports Server (NTRS)

    Iacobellis, Sam F.; Frouin, Robert; Razafimpanilo, Herisoa; Somerville, Richard C. J.; Piper, Stephen C.

    1994-01-01

    The effect of north African savanna fires on atmospheric CO2 is investigated using a tracer transport model. The model uses winds from operational numerical weather prediction analyses and provides CO2 concentrations as a function of space and time. After a spin-up period of several years, biomass-burning sources are added, and model experiments are run for an additional year, utilizing various estimates of CO2 sources. The various model experiments show that biomass burning in the north African savannas significantly affects CO2 concentrations in South America. The effect is more pronounced during the period from January through March, when biomass burning in South America is almost nonexistent. During this period, atmospheric CO2 concentrations in parts of South America typically may increase by 0.5 to 0.75 ppm at 970 mbar, the average pressure of the lowest model layer. These figures are above the probable uncertainty level, as model runs with biomass-burning sources estimated from independent studies using distinct data sets and techniques indicate. From May through September, when severe biomass burning occurs in South America, the effect of north African savanna fires over South America has become generally small at 970 mbar, but north of the equator it may be of the same magnitude or larger than the effect of South American fires. The CO2 concentration increase in the extreme northern and southern portions of South America, however, is mostly due to southern African fires, whose effect may be 2-3 times larger than the effect of South American fires at 970 mbar. Even in the central part of the continent, where local biomass-burning emissions are maximum, southern African fires contribute to at least 15% of the CO2 concentration increase at 970 mbar. At higher levels in the atmosphere, less CO2 emitted by north African savanna fires reaches South America, and at 100 mbar no significant amount of CO2 is transported across the Atlantic Ocean. The vertical

  11. The Lake Albert Rift (uganda, East African Rift System): Deformation, Basin and Relief Evolution Since 17 Ma

    NASA Astrophysics Data System (ADS)

    Brendan, Simon; François, Guillocheau; Cécile, Robin; Olivier, Dauteuil; Thierry, Nalpas; Martin, Pickford; Brigitte, Senut; Philippe, Lays; Philippe, Bourges; Martine, Bez

    2016-04-01

    This study is based on a coupled basin infilling study and a landforms analysis of the Lake Albert Rift located at the northern part of the western branch of the East African Rift. The basin infilling study is based on both subsurface data and outcrops analysis. The objective was to (1) obtain an age model based on onshore mammals biozones, (2) to reconstruct the 3D architecture of the rift using sequence stratigraphy correlations and seismic data interpretation, (3) to characterize the deformation and its changes through times and (4) to quantify the accommodation for several time intervals. The infilling essentially consists of isopach fault-bounded units composed of lacustrine deposits wherein were characterized two major unconformities dated at 6.2 Ma (Uppermost Miocene) and 2.7 Ma (Pliocene-Pleistocene boundary), coeval with major subsidence and climatic changes. The landforms analysis is based on the characterization and relative dating (geometrical relationships with volcanism) of Ugandan landforms which consist of stepped planation surfaces (etchplains and peplians) and incised valleys. We here proposed a seven-steps reconstruction of the deformation-erosion-sedimentation relationships of the Lake Albert Basin and its catchments: - 55-45 Ma: formation of laterites corresponding to the African Surface during the very humid period of the Lower-Middle Eocene; - 45-22: stripping of the African Surface in response of the beginning of the East-African Dome uplift and formation of a pediplain which associated base level is the Atlantic Ocean; - 17-2.5 Ma: Initiation of the Lake Albert Basin around 17 Ma and creation of local base levels (Lake Albert, Edward and George) on which three pediplains tend to adapt; - 18 - 16 Ma to 6.2 Ma: "Flexural" stage (subsidence rate: 150-200 m/Ma; sedimentation rate 1.3 km3/Ma between 17 and 12 Ma and 0.6 km3/Ma from 12 to 6 Ma) - depocenters location (southern part of Lake Albert Basin) poorly controlled by fault; - 6.2 Ma to 2

  12. The influence of humidity, temperature, and oral contraceptive in tear

    NASA Astrophysics Data System (ADS)

    Sousa, Raul A. R. C.; Ribeiro, Tânia L. C.; Moreira, Sandra M. B.; Baptista, António M. G.

    2013-11-01

    The aim of this study is to ascertain whether the quantity and quality of tear and eye subjective comfort are influenced by the temperature, humidity and oral Contraceptives Taking or Non-taking (CTNT). Forty-one students, females, from the University of Minho, Braga, Portugal, aged (mean+/-1standard deviation) of 21.51+/-1.85 years, ranging from 20 to 30 years, participated in this study. The McMonnies Questionnaire (MMQ), Break Up Time (BUT) and Phenol Red Test (PRT) were accessed between 14-17 hours in four sets of visits throughout the year: Visit 1, Visit 2, Visit 3 and Visit 4. The PRT and BUT values (mean+/-1standard deviation) for Visit 1, Visit 2, Visit 3 and Visit 4 were respectively 23.88+/-6.50mm, 22.29+/-8.00mm, 23.61+/-6.75mm, 22.88+/-7.00mm and 6.02+/-1.58s, 5.62+/-1.22s, 5.23+/-0.88s, 5.53+/-1. 42s. The MMQ scores for Visit 1, Visit 2, Visit 3 and Visit 4 ranged from 2-13, 2-15, 1-14 and 2-14 with medians of 6, 7, 6 and 6, respectively. The influence of temperature, humidity and CTNT on PRT, BUT and MMQ were evaluated using generalized linear mixed model. For BUT and MMQ statistical significant effects were found regarding temperature and humidity. The temperature and humidity influenced the tear quality and subjective comfort but did not influence the tear quantity. The CTNT did not influence tear quantity, quality or subjective eye comfort.

  13. Energy Efficient Crawlspace Foundation Retrofit: Mixed Humid Climate

    SciTech Connect

    Del Bianco, M.; Wiehagen, J.

    2013-01-01

    Residential quality management systems have most often been designed for new home construction. To address quality in existing homes in the form of Scopes of Work (SOW), the NAHB Research Center began with a new construction scope of work and applied it to an existing home project. This document is intended to outline the steps of translating a new home construction SOW to SOW for retrofit and addressed crawlspace foundations in a mixed-humid climate.

  14. Humidity sensing properties of CNT-OD-VETP nanocomposite films

    NASA Astrophysics Data System (ADS)

    Saleem, M.; Karimov, Kh. S.; Karieva, Z. M.; Mateen, A.

    2010-11-01

    In this study, the blend of orange dye (OD), C 17H 17N 5O 2 (5 wt%), vinyl-ethynyl-trimethyl-piperidole (VETP), C 12H 19NO, (5 wt%) and carbon nanotube (CNT) powder (10 wt%) in a mixture of distilled water (80 wt%) and spirit were drop-casted on glass substrates with pre-deposited surface-type silver electrodes to fabricate CNT-OD-VETP nanocomposite thin films. In the process of thin films deposition, 2 V DC was applied to Ag electrodes. The thicknesses of the CNT-OD-VETP films were in the range of 10-15 μm. The I-V characteristics of the surface-type Ag/CNT-OD-VETP/Ag samples showed rectification behavior. The effect of humidity on the electrical properties of the nanocomposite films was investigated by measurement of the capacitance and dissipation of the samples at two different frequencies of the applied voltage: 120 Hz and 1 kHz. The resistance of the samples was determined from values of dissipation. It was observed that at 120 Hz and 1 kHz, under humidity of up to 90% RH, the capacitance of the cell increased by 7.4×10 3 and 740 times and resistance decreased by 2.3×10 4 and 3.8×10 4 times, accordingly, with respect to 40% RH conditions. The average response and recovery times of the films were obtained by capacitance-time measurements to evaluate the dynamics of the water vapor absorption and desorption processes. The experimental results have been supported by the simulation of the capacitance-humidity relationship. It is assumed that the humidity response of the cell is associated with diffusion of water vapors and doping of the semiconductor nanocomposite by water molecules.

  15. Kinetics of the humid aging of magnetic recording tape

    NASA Technical Reports Server (NTRS)

    Bertram, H. N.; Cuddihy, E. F.

    1982-01-01

    The kinetics of the hydrolysis of polyester urethane binders of magnetic recording tape is described. Kinetic data were generated from measurements of acetone-extractable hydrolyzed binder products versus time for various humidity-temperature environments. These data can be described by a linear, single product, reversible rate equation. This equation, coupled with measurements on the effect of hydrolysis on recorded tape performance, is used to predict proper environmental storage conditions for magnetic tape.

  16. Why alite stops hydrating below 80% relative humidity

    SciTech Connect

    Flatt, Robert J.; Scherer, George W.; Bullard, Jeffrey W.

    2011-09-15

    It has been observed that the hydration of cement paste stops when the relative humidity drops below about 80%. A thermodynamic analysis shows that the capillary pressure exerted at that RH shifts the solubility of tricalcium silicate, so that it is in equilibrium with water. This is a reflection of the chemical shrinkage in this system: according to Le Chatelier's principle, since the volume of the products is less than that of the reactants, a negative (capillary) pressure opposes the reaction.

  17. Impact of Ambient Humidity on Child Health: A Systematic Review

    PubMed Central

    Gao, Jinghong; Sun, Yunzong; Lu, Yaogui; Li, Liping

    2014-01-01

    Background and Objectives Changes in relative humidity, along with other meteorological factors, accompany ongoing climate change and play a significant role in weather-related health outcomes, particularly among children. The purpose of this review is to improve our understanding of the relationship between ambient humidity and child health, and to propose directions for future research. Methods A comprehensive search of electronic databases (PubMed, Medline, Web of Science, ScienceDirect, OvidSP and EBSCO host) and review of reference lists, to supplement relevant studies, were conducted in March 2013. All identified records were selected based on explicit inclusion criteria. We extracted data from the included studies using a pre-designed data extraction form, and then performed a quality assessment. Various heterogeneities precluded a formal quantitative meta-analysis, therefore, evidence was compiled using descriptive summaries. Results Out of a total of 3797 identified records, 37 papers were selected for inclusion in this review. Among the 37 studies, 35% were focused on allergic diseases and 32% on respiratory system diseases. Quality assessment revealed 78% of the studies had reporting quality scores above 70%, and all findings demonstrated that ambient humidity generally plays an important role in the incidence and prevalence of climate-sensitive diseases among children. Conclusions With climate change, there is a significant impact of ambient humidity on child health, especially for climate-sensitive infectious diseases, diarrhoeal diseases, respiratory system diseases, and pediatric allergic diseases. However, some inconsistencies in the direction and magnitude of the effects are observed. PMID:25503413

  18. Performance Evaluation of a Hot-Humid Climate Community

    SciTech Connect

    Osser, R.; Kerrigan, P.

    2012-02-01

    Project Home Again is a development in New Orleans, LA created to provide new homes to victims of Hurricane Katrina. Building Science Corporation acted as a consultant for the project, advocating design strategies for durability, flood resistance, occupant comfort, and low energy use while maintaining cost effectiveness. These techniques include the use of high density spray foam insulation, LoE3 glazing, and supplemental dehumidification to maintain comfortable humidity levels without unnecessary cooling.

  19. The African Pediatric Fellowship Program: Training in Africa for Africans.

    PubMed

    Wilmshurst, Jo M; Morrow, Brenda; du Preez, Avril; Githanga, David; Kennedy, Neil; Zar, Heather J

    2016-01-01

    Africa has a significant burden of childhood disease, with relatively few skilled health care professionals. The African Paediatric Fellowship Programme was developed by the Department of Pediatrics and Child Health at the University of Cape Town to provide relevant training for African child health professionals, by Africans, within Africa. Trainees identified by partner academic institutions spend 6 months to 2 years training in the Department of Pediatrics and allied disciplines. They then return to their home institution to build practice, training, research, and advocacy. From 2008 to 2015, 73 physicians have completed or are completing training in general pediatrics or a pediatric subspecialty. At 1 year posttraining, 98% to 100% are practicing back in their home institution. The impact of the returning fellows is evident from their practice interventions, research collaborations, and positions as stakeholders who can change health care policies. Thirty-three centers in 13 African countries are partners with the program, and the program template is now followed by other partner sites in Africa. Increasing and retaining the skills pool of African child health specialists is building a network of motivated, highly skilled clinicians who are equipped to advance child health in Africa. PMID:26659458

  20. East African Rift

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Places where the earth's crust has formed deep fissures and the plates have begun to move apart develop rift structures in which elongate blocks have subsided relative to the blocks on either side. The East African Rift is a world-famous example of such rifting. It is characterized by 1) topographic deep valleys in the rift zone, 2) sheer escarpments along the faulted walls of the rift zone, 3) a chain of lakes within the rift, most of the lakes highly saline due to evaporation in the hot temperatures characteristic of climates near the equator, 4) voluminous amounts of volcanic rocks that have flowed from faults along the sides of the rift, and 5) volcanic cones where magma flow was most intense. This example in Kenya displays most of these features near Lake Begoria.

    The image was acquired December 18, 2002, covers an area of 40.5 x 32 km, and is located at 0.1 degrees north latitude, 36.1 degrees east longitude.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

  1. Humidity-regulated dormancy onset in the Fabaceae: a conceptual model and its ecological implications for the Australian wattle Acacia saligna

    PubMed Central

    Tozer, Mark G.; Ooi, Mark K. J.

    2014-01-01

    Background and aims Seed dormancy enhances fitness by preventing seeds from germinating when the probability of seedling survival and recruitment is low. The onset of physical dormancy is sensitive to humidity during ripening; however, the implications of this mechanism for seed bank dynamics have not been quantified. This study proposes a model that describes how humidity-regulated dormancy onset may control the accumulation of a dormant seed bank, and seed experiments are conducted to calibrate the model for an Australian Fabaceae, Acacia saligna. The model is used to investigate the impact of climate on seed dormancy and to forecast the ecological implications of human-induced climate change. Methods The relationship between relative humidity and dormancy onset was quantified under laboratory conditions by exposing freshly matured non-dormant seeds to constant humidity levels for fixed durations. The model was field-calibrated by measuring the response of seeds exposed to naturally fluctuating humidity. The model was applied to 3-hourly records of humidity spanning the period 1972–2007 in order to estimate both temporal variability in dormancy and spatial variability attributable to climatic differences among populations. Climate change models were used to project future changes in dormancy onset. Key Results A sigmoidal relationship exists between dormancy and humidity under both laboratory and field conditions. Seeds ripened under field conditions became dormant following very short exposure to low humidity (<20 %). Prolonged exposure at higher humidity did not increase dormancy significantly. It is predicted that populations growing in a temperate climate produce 33–55 % fewer dormant seeds than those in a Mediterranean climate; however, dormancy in temperate populations is predicted to increase as a result of climate change. Conclusions Humidity-regulated dormancy onset may explain observed variation in physical dormancy. The model offers a systematic

  2. South African Particulates

    Atmospheric Science Data Center

    2013-04-16

    ... title:  Airborne Particulates over Southern Africa     View Larger Image ... of airborne particulates, or aerosols, over Southern Africa during the period August 14 - September 29, 2000. Low particle ...

  3. Observational Constraints of Humidity Climatology From GPS Radio Occultation measurements

    NASA Astrophysics Data System (ADS)

    Vergados, P.; Jiang, J. H.; Su, H.; Mannucci, A. J.

    2014-12-01

    Recent studies have shown large differences in the humidity climatology of the upper troposphere (UT) region between global models and observations. Such discrepancies can lead to large differences in the water vapor feedback estimations between models, reanalyses and satellite observations, and therefore climate projection uncertainties. Global Circulation Models (GCMs) could also mischaracterize the middle troposphere moist convection leading to erroneous conclusions about the water vapor vertical distribution and horizontal transport. We observationally constrain the UT humidity by employing high accuracy (<1.0%) and high vertical resolution (100-200 m) Global Positioning System Radio Occultation (GPSRO) refractivity measurements. Preliminary results from GPSRO reveal a significantly drier tropical boundary layer than both ECMWF and MERRA reanalyses. In the middle and upper troposphere, GPSRO is moister than ECMWF but drier than MERRA. These features are more pronounced at equatorial latitudes. These differences could have greater repercussions with regards to the water vapor feedback estimation. Also, zonally varying distributions of relative humidity (RH) from GPSRO, MERRA and ECMWF were also correlated with precipitation measurements from the Global Precipitation Climatology Project (GPCP). We found latitudinal differences between maxima of precipitation and RH, which could imply that large-scale horizontal transport in the boundary layer plays a critical role to governing the coupling strength between precipitation and RH. The application of GPSRO data in constraining the underlying model physics will be discussed.

  4. A Humidity-Driven Prediction System for Influenza Outbreaks

    NASA Astrophysics Data System (ADS)

    Thrastarson, H. T.; Teixeira, J.

    2015-12-01

    Recent studies have highlighted the role of absolute (or specific) humidity conditions as a leading explanation for the seasonal behavior of influenza outbreaks in temperate regions. If the timing and intensity of seasonal influenza outbreaks can be forecast, this would be of great value for public health response efforts. We have developed and implemented a SIRS (Susceptible-Infectious-Recovered-Susceptible) type numerical prediction system that is driven by specific humidity to predict influenza outbreaks. For the humidity, we have explored using both satellite data from the AIRS (Atmospheric Infrared Sounder) instrument as well as ERA-Interim re-analysis data. We discuss the development, testing, sensitivities and limitations of the prediction system and show results for influenza outbreaks in the United States during the years 2010-2014 (modeled in retrospect). Comparisons are made with other existing prediction systems and available data for influenza outbreaks from Google Flu Trends and the CDC (Center for Disease Control), and the incorporation of these datasets into the forecasting system is discussed.

  5. Optical fiber humidity sensor based on evanescent-wave scattering.

    PubMed

    Xu, Lina; Fanguy, Joseph C; Soni, Krunal; Tao, Shiquan

    2004-06-01

    The phenomenon of evanescent-wave scattering (EWS) is used to design an optical-fiber humidity sensor. Porous solgel silica (PSGS) coated on the surface of a silica optical-fiber core scatters evanescent waves that penetrate the coating layer. Water molecules in the gas phase surrounding the optical fiber can be absorbed into the inner surface of the pores of the porous silica. The absorbed water molecules form a thin layer of liquid water on the inner surface of the porous silica and enhance the EWS. The amount of water absorbed into the PSGS coating is in dynamic equilibrium with the water-vapor pressure in the gas phase. Therefore the humidity in the air can be quantitatively determined with fiber-optic EWS caused by the PSGS coating. The humidity sensor reported here is fast in response, reversible, and has a wide dynamic range. The possible interference caused by EWS to an optical-fiber gas sensor with a reagent-doped PSGS coating as a transducer is also discussed. PMID:15209243

  6. Brood comb as a humidity buffer in honeybee nests

    NASA Astrophysics Data System (ADS)

    Ellis, Michael B.; Nicolson, Sue W.; Crewe, Robin M.; Dietemann, Vincent

    2010-04-01

    Adverse environmental conditions can be evaded, tolerated or modified in order for an organism to survive. During their development, some insect larvae spin cocoons which, in addition to protecting their occupants against predators, modify microclimatic conditions, thus facilitating thermoregulation or reducing evaporative water loss. Silk cocoons are spun by honeybee ( Apis mellifera) larvae and subsequently incorporated into the cell walls of the wax combs in which they develop. The accumulation of this hygroscopic silk in the thousands of cells used for brood rearing may significantly affect nest homeostasis by buffering humidity fluctuations. This study investigates the extent to which the comb may influence homeostasis by quantifying the hygroscopic capacity of the cocoons spun by honeybee larvae. When comb containing cocoons was placed at high humidity, it absorbed 11% of its own mass in water within 4 days. Newly drawn comb composed of hydrophobic wax and devoid of cocoons absorbed only 3% of its own mass. Therefore, the accumulation of cocoons in the comb may increase brood survivorship by maintaining a high and stable humidity in the cells.

  7. Implications of Enhanced Relative Humidity in Cold Tropical Cirrus

    NASA Technical Reports Server (NTRS)

    Jensen, Eric; Pfister, Leonhard

    2004-01-01

    In situ measurements of water vapor concentration and temperature in tropical cirrus during the CRYSTAL-FACE and Pre-AVE missions indicate that the steady-state relative humidity within cirrus at T less than 200 K is about 20-30% higher than ice saturation. These measurements challenge the conventional belief, that any water vapor in excess of ice saturation should be depleted by crystal growth given sufficient time. Detailed simulations of thin cirrus near the tropopause indicate that this enhanced steady-state relative humidity increases ice number densities, decreases crystal sizes and extends cloud lifetimes. The areal coverage of thin cirrus in the tropics is increased rather than decreased as indicated by simpler conceptual models. Perhaps most significantly, the increased steady-state H2O saturation mixing ratio over ice in thin cirrus near the tropopause results in about a 0.5-1 ppmv increase in the amount of water that can enter the stratosphere across the tropical tropopause cold trap. Hence, the enhanced steady-state relative humidity in cold cirrus implies that lower tropopause temperatures are required to explain the observed stratospheric water vapor mixing ratios than previously assumed.

  8. Impacts of climate and land use changes on the hydrological and erosive response of a humid and dry Mediterranean catchment

    NASA Astrophysics Data System (ADS)

    Serpa, Dalila; Nunes, João Pedro; Santos, Juliana; Sampaio, Elsa; Jacinto, Rita; Veiga, Sandro; Lima, Júlio; Moreira, Madalena; Corte-Real, João; Keizer, Jan Jacob; Abrantes, Nelson

    2016-04-01

    The impacts of climate and land use changes on streamflow and sediment export were evaluated for a humid (São Lourenço) and a dry (Guadalupe) Mediterranean catchment, using the Soil and Water Assessment Tool (SWAT) model. SWAT was able to produce viable streamflow and sediment export simulations for both catchments, which provided a baseline for investigating climate and land use changes under the A1B and B1 emission scenarios for the period between 2071 and 2100. Compared to the baseline period (1971-2000), climate change scenarios forecasted a decrease in annual precipitation in both catchments (humid, both scenarios: -12%; dry, both scenarios: -8%), but with strong increases during winter. Land use changes followed a socio-economic storyline in which traditional agriculture was replaced by more profitable land uses, i.e. corn and commercial forestry at the humid site and sunflower at the dry site. Climate changes led to a decrease of streamflow in both catchments (humid, both scenarios: -13%; dry, A1B: -14%; B1: -18%), mostly as a consequence of the projected decrease in rainfall. Land use changes led to small increases in flow discharge, but a higher increase was observed for the dry site under scenario A1B (humid, A1B: +0.3%; B1: +1%; dry, A1B: +6%; B1: +0.3%). The combination of climate and land use scenarios was mostly dominated by the climatic response, since a decrease in streamflow was observed for both catchments (humid, A1B: -13%; B1: -12%; dry, A1B: -8%; B1: -18%). Regarding the erosive response, clear differences were observed between catchments mostly due to differences in both the present-day and forecasted vegetation types. Climate scenarios led to a decrease in sediment export at the humid catchment (A1B: -11%; B1: -9%) and to an increase at the dry catchment (A1B: +24%; B1: +22%) in the first case due to the predominant vegetation type (vineyards and maritime pine) providing year-round cover, while in the second, due to annual crops (wheat and

  9. An African ethic for nursing?

    PubMed

    Haegert, S

    2000-11-01

    This article derives from a doctoral thesis in which a particular discourse was used as a 'paradigm case'. From this discourse an ethic set within a South African culture arose. Using many cultural 'voices' to aid the understanding of this narrative, the ethic shows that one can build on both a 'justice' and a 'care' ethic. With further development based on African culture one can take the ethic of care deeper and reveal 'layers of understanding'. Care, together with compassion, forms the foundation of morality. Nursing ethics has followed particular western moral philosophers. Often nursing ethics has been taught along the lines of Kohlberg's theory of morality, with its emphasis on rules, rights, duties and general obligations. These principles were universalistic, masculine and noncontextual. However, there is a new ethical movement among Thomist philosophers along the lines to be expounded in this article. Nurses such as Benner, Bevis, Dunlop, Fry and Gadow--to name but a few--have welcomed the concept of an 'ethic of care'. Gilligan's work gave a feminist view and situated ethics in the everyday aspects of responsiveness, responsibility, context and concern. Shutte's search for a 'philosophy for Africa' has resulted in finding similarities in Setiloane and in Senghor with those of Thomist philosophers. Using this African philosophy and a research participant's narrative, an African ethic evolves out of the African proverb: 'A person is a person through other persons', or its alternative rendering: 'I am because we are: we are because I am.' This hermeneutic narrative reveals 'the way affect imbues activity with ethical meaning' within the context of a black nursing sister in a rural South African hospital. It expands upon the above proverb and incorporates the South African constitutional idea of 'Ubuntu' (compassion and justice or humanness). PMID:11221391

  10. Ocean Temperature and Humidity Sensor Design Based on SHT75 Module

    NASA Astrophysics Data System (ADS)

    Zhao, Jie; Yang, Li; Gai, Zhigang; Yang, Junxian; Yang, Ying

    SHT75 is a temperature and humidity module with high precision, low power consumption, two line output. An intelligent output temperature and humidity sensor is developed based on this module. The hardware and software design are introduced in detail in this paper. In addition, temperature and humidity correction parameters can be calculated by polynomial curve fitting. Experimental results show that the polynomial curve fitting after correction for temperature and humidity sensor can reach to more accurate measurement accuracy.

  11. A Phylogeographic Investigation of African Monkeypox

    PubMed Central

    Nakazawa, Yoshinori; Mauldin, Matthew R.; Emerson, Ginny L.; Reynolds, Mary G.; Lash, R. Ryan; Gao, Jinxin; Zhao, Hui; Li, Yu; Muyembe, Jean-Jacques; Mbala Kingebeni, Placide; Wemakoy, Okito; Malekani, Jean; Karem, Kevin L.; Damon, Inger K.; Carroll, Darin S.

    2015-01-01

    Monkeypox is a zoonotic disease caused by a virus member of the genus Orthopoxvirus and is endemic to Central and Western African countries. Previous work has identified two geographically disjuct clades of monkeypox virus based on the analysis of a few genomes coupled with epidemiological and clinical analyses; however, environmental and geographic causes of this differentiation have not been explored. Here, we expand previous phylogenetic studies by analyzing a larger set of monkeypox virus genomes originating throughout Sub-Saharan Africa to identify possible biogeographic barriers associated with genetic differentiation; and projected ecological niche models onto environmental conditions at three periods in the past to explore the potential role of climate oscillations in the evolution of the two primary clades. Analyses supported the separation of the Congo Basin and West Africa clades; the Congo Basin clade shows much shorter branches, which likely indicate a more recent diversification of isolates within this clade. The area between the Sanaga and Cross Rivers divides the two clades and the Dahomey Gap seems to have also served as a barrier within the West African clade. Contraction of areas with suitable environments for monkeypox virus during the Last Glacial Maximum, suggests that the Congo Basin clade of monkeypox virus experienced a severe bottleneck and has since expanded its geographic range. PMID:25912718

  12. Quiet time enhancements over African latitudes

    NASA Astrophysics Data System (ADS)

    Orford, Nicola; Katamzi, Zama; Buresova, Dalia

    2016-07-01

    F2 layer disturbances not related to geomagnetic activity are known as quiet time enhancements (QTEs). The phenomenon of QTEs has not yet been studied over African latitudes. We therefore explore the occurrence of QTEs over Africa in order to expand our knowledge on the behaviour of the ionosphere over this region. Several GPS stations in the middle to equatorial latitudes, during the solar minimum (2009) and near solar maximum (2013), are used. This data was examined for possible trends in variation with solar cycle, season and latitude as well as time of commencement of enhancements. Over the southern mid-latitude region of Africa we have observed that the QTEs are more likely to commence during the night in both solar minimum and maximum, however a slightly larger portion of daytime commencements during solar minimum than during solar maximum were observed. The total number of enhancements for the solar minimum period appears greater than during solar maximum. A seasonal trend is seen with the maximum number of enhancements occurring in summer during solar minimum and in winter during solar maximum. We explore further whether these trends are mirrored or different at low latitude/equatorial African regions.

  13. Reconstructing the vertical profile of humidity on the basis of the vertical profile of temperature

    NASA Technical Reports Server (NTRS)

    Bazlova, T. I.

    1974-01-01

    The vertical profile of humidity in the atmosphere is developed on the basis of the vertical profile of temperature using an empirical formula linking changes in humidity with changes in temperature and altitude. The atmosphere is divided into three layers by altitude, since the condition for the formation of humidity varies with altitude.

  14. Humidity Effects on Fragmentation in Plasma-Based Ambient Ionization Sources.

    PubMed

    Newsome, G Asher; Ackerman, Luke K; Johnson, Kevin J

    2016-01-01

    Post-plasma ambient desorption/ionization (ADI) sources are fundamentally dependent on surrounding water vapor to produce protonated analyte ions. There are two reports of humidity effects on ADI spectra. However, it is unclear whether humidity will affect all ADI sources and analytes, and by what mechanism humidity affects spectra. Flowing atmospheric pressure afterglow (FAPA) ionization and direct analysis in real time (DART) mass spectra of various surface-deposited and gas-phase analytes were acquired at ambient temperature and pressure across a range of observed humidity values. A controlled humidity enclosure around the ion source and mass spectrometer inlet was used to create programmed humidity and temperatures. The relative abundance and fragmentation of molecular adduct ions for several compounds consistently varied with changing ambient humidity and also were controlled with the humidity enclosure. For several compounds, increasing humidity decreased protonated molecule and other molecular adduct ion fragmentation in both FAPA and DART spectra. For others, humidity increased fragment ion ratios. The effects of humidity on molecular adduct ion fragmentation were caused by changes in the relative abundances of different reagent protonated water clusters and, thus, a change in the average difference in proton affinity between an analyte and the population of water clusters. Control of humidity in ambient post-plasma ion sources is needed to create spectral stability and reproducibility. PMID:26384684

  15. Humidity Effects on Fragmentation in Plasma-Based Ambient Ionization Sources

    NASA Astrophysics Data System (ADS)

    Newsome, G. Asher; Ackerman, Luke K.; Johnson, Kevin J.

    2016-01-01

    Post-plasma ambient desorption/ionization (ADI) sources are fundamentally dependent on surrounding water vapor to produce protonated analyte ions. There are two reports of humidity effects on ADI spectra. However, it is unclear whether humidity will affect all ADI sources and analytes, and by what mechanism humidity affects spectra. Flowing atmospheric pressure afterglow (FAPA) ionization and direct analysis in real time (DART) mass spectra of various surface-deposited and gas-phase analytes were acquired at ambient temperature and pressure across a range of observed humidity values. A controlled humidity enclosure around the ion source and mass spectrometer inlet was used to create programmed humidity and temperatures. The relative abundance and fragmentation of molecular adduct ions for several compounds consistently varied with changing ambient humidity and also were controlled with the humidity enclosure. For several compounds, increasing humidity decreased protonated molecule and other molecular adduct ion fragmentation in both FAPA and DART spectra. For others, humidity increased fragment ion ratios. The effects of humidity on molecular adduct ion fragmentation were caused by changes in the relative abundances of different reagent protonated water clusters and, thus, a change in the average difference in proton affinity between an analyte and the population of water clusters. Control of humidity in ambient post-plasma ion sources is needed to create spectral stability and reproducibility.

  16. Influence of the hydration by the environmental humidity on the metallic speciation and the photocatalytic activity of Cr/MCM-41

    NASA Astrophysics Data System (ADS)

    Elías, Verónica R.; Sabre, Ema V.; Winkler, Elin L.; Andrini, Leandro; Requejo, Félix G.; Casuscelli, Sandra G.; Eimer, Griselda A.

    2014-05-01

    The influence of the environmental humidity on the Cr species deposited on inorganic supports like MCM-41 silicates was analyzed by UV-vis Diffuse Reflectance (UV-vis RD), Electronic Spin Resonance (ESR) and X-ray near-edge (XANES) spectroscopy. Metal speciation could be inferred, finding that prolonged exposure periods under environmental humidity provoked the reduction of the active Cr6+ species and thus, the decrease of the Cr/MCM-41 photoactivity. After the Ti loading over the Cr modified samples, Cr species and the photoactivity were not notably influenced by the humidity exposure. Thus, it could be concluded that the presence of Ti is important because the TiO2 cover protects the oxidized Cr species, stabilizing them.

  17. Roller compaction: Effect of relative humidity of lactose powder.

    PubMed

    Omar, Chalak S; Dhenge, Ranjit M; Palzer, Stefan; Hounslow, Michael J; Salman, Agba D

    2016-09-01

    The effect of storage at different relative humidity conditions, for various types of lactose, on roller compaction behaviour was investigated. Three types of lactose were used in this study: anhydrous lactose (SuperTab21AN), spray dried lactose (SuperTab11SD) and α-lactose monohydrate 200M. These powders differ in their amorphous contents, due to different manufacturing processes. The powders were stored in a climatic chamber at different relative humidity values ranging from 10% to 80% RH. It was found that the roller compaction behaviour and ribbon properties were different for powders conditioned to different relative humidities. The amount of fines produced, which is undesirable in roller compaction, was found to be different at different relative humidity. The minimum amount of fines produced was found to be for powders conditioned at 20-40% RH. The maximum amount of fines was produced for powders conditioned at 80% RH. This was attributed to the decrease in powder flowability, as indicated by the flow function coefficient ffc and the angle of repose. Particle Image Velocimetry (PIV) was also applied to determine the velocity of primary particles during ribbon production, and it was found that the velocity of the powder during the roller compaction decreased with powders stored at high RH. This resulted in less powder being present in the compaction zone at the edges of the rollers, which resulted in ribbons with a smaller overall width. The relative humidity for the storage of powders has shown to have minimal effect on the ribbon tensile strength at low RH conditions (10-20%). The lowest tensile strength of ribbons produced from lactose 200M and SD was for powders conditioned at 80% RH, whereas, ribbons produced from lactose 21AN at the same condition of 80% RH showed the highest tensile strength. The storage RH range 20-40% was found to be an optimum condition for roll compacting three lactose powders, as it resulted in a minimum amount of fines in the

  18. African easterly wave energetics on intraseasonal timescales

    NASA Astrophysics Data System (ADS)

    Alaka, Ghassan J., Jr.

    African easterly waves (AEWs) are synoptic-scale eddies that dominate North African weather in boreal summer. AEWs propagate westward with a maximum amplitude near 700 hPa and a period of 2.5-6-days. AEWs and associated perturbation kinetic energy (PKE) exhibit significant intraseasonal variability in tropical North Africa during boreal summer, which directly impacts local agriculture and tropical cyclogenesis. This study performs a comprehensive analysis of the 30-90-day variability of AEWs and associated energetics using both reanalysis data and model output. Specifically, the PKE and perturbation available potential energy (PAPE) budgets are used to understand the factors that contribute to PKE maxima in West Africa and the extent to which these surges of AEW activity are modulated by the Madden-Julian oscillation (MJO). The role of the MJO in the intraseasonal variability of AEWs is assessed by comparing PKE sources as a function of an MJO index and a local 30-90-day West African PKE index. Since East Africa is an initiation zone for AEW activity and is modulated by the MJO, the relationship between this region and West Africa is a primary focus in this study. The intraseasonal variability of AEW energetics is first investigated in reanalysis products. While reanalysis data depicts a similar evolution of 30-90-day PKE anomalies in both the MJO and a local PKE index, the MJO index describes only a small (yet still significant) fraction of the local 30-90-day variance. In boreal summers with more significant MJO days, the correlation between the two indices is higher. Baroclinic energy conversions are important for the initiation of 30-90-day West African PKE events east of Lake Chad. In West Africa, both barotropic and baroclinic energy conversions maintain positive PKE anomalies before they propagate into the Atlantic. The primary role of diabatic heating is to destroy PAPE in a negative feedback to baroclinic energy conversions in West Africa. More frequent

  19. Influence of the hydration by the environmental humidity on the metallic speciation and the photocatalytic activity of Cr/MCM-41

    SciTech Connect

    Elías, Verónica R.; Sabre, Ema V.; Winkler, Elin L.; Andrini, Leandro; Requejo, Félix G.; Casuscelli, Sandra G.; Eimer, Griselda A.

    2014-05-01

    The influence of the environmental humidity on the Cr species deposited on inorganic supports like MCM-41 silicates was analyzed by UV–vis Diffuse Reflectance (UV–vis RD), Electronic Spin Resonance (ESR) and X-ray near-edge (XANES) spectroscopy. Metal speciation could be inferred, finding that prolonged exposure periods under environmental humidity provoked the reduction of the active Cr{sup 6+} species and thus, the decrease of the Cr/MCM-41 photoactivity. After the Ti loading over the Cr modified samples, Cr species and the photoactivity were not notably influenced by the humidity exposure. Thus, it could be concluded that the presence of Ti is important because the TiO{sub 2} cover protects the oxidized Cr species, stabilizing them. - Graphical abstract: The load of Ti on the Cr modified MCM-41 produces a TiO{sub 2} cover that protects the active Cr species from their reduction by the environmental humidity. - Highlights: • Spectroscopic analysis shows presence of Cr{sup 6+}/Cr{sup 5+} in calcined/re-calcined samples. • Cr{sup 3+} species increase for hydrated samples causing their photoactivity decrease. • Samples with high Cr loadings are more sensitive to environmental humidity presence. • TiO{sub 2} cover protects oxidized Cr species from their reduction by the water. • Ti is important to allow a synergistic effect and to stabilize active Cr{sup 6+}/Cr{sup 5+}.

  20. The effect of the relative humidity and the specific humidity on the determination of the climate regions in Turkey

    NASA Astrophysics Data System (ADS)

    Sahin, Sinan; Cigizoglu, H. Kerem

    2013-05-01

    All elements of climate that affect climatic events must be taken into account such that the climate regions are determined with exactitude. To this end, data on maximum temperature (Tx), minimum temperature (Tn), mean temperature (Tm), and precipitation (Pt) as well as local pressure (Ps), mean wind (WN), relative humidity (RH), and specific humidity (SH) have been investigated statistically and graphically. The specific humidity data calculated using Tm, Ps, and RH data and statistical comparisons have shown that there are no drawbacks to using SH in climatologic studies. According to principal component analysis, it was concluded that RH and SH should be used together with Tx, Tm, Tn, and Pt for the determination of the climate regions. Two cluster analysis methods, Ward's method and Kohonen neural network technique, were used to show the effect of RH and SH. A comparison of the cluster's stability between the limited and high number of stations shows that Ward's method and Kohonen neural network are very stable in both cases. It was also determined that RH does not change the outline of climate regions but that it affects the zones of climate transition. It was observed that clusters determined by using Tm, Pt, and RH provide relatively more distinctive clusters in the data space than clusters determined by using Tm, Pt, and SH.

  1. African American Males. A Critical Link in the African American Family.

    ERIC Educational Resources Information Center

    Jones, Dionne J., Ed.

    African Americans are experiencing extreme stress in the United States, and African-American males appear to suffer the most. The chapters in this volume examine some of the issues confronting African-American men today. They include: (1) "Introduction" (Dionne J. Jones); (2) "Reaffirming Young African American Males: Mentoring and Community…

  2. African American Preschoolers' Language, Emergent Literacy Skills, and Use of African American English: A Complex Relation

    ERIC Educational Resources Information Center

    Connor, Carol McDonald; Craig, Holly K.

    2006-01-01

    Purpose: This study examined the relation between African American preschoolers' use of African American English (AAE) and their language and emergent literacy skills in an effort to better understand the perplexing and persistent difficulties many African American children experience learning to read proficiently. Method: African American…

  3. Dependence on material choice of degradation of organic solar cells following exposure to humid air

    PubMed Central

    Glen, Tom S.; Scarratt, Nicholas W.; Yi, Hunan; Iraqi, Ahmed; Wang, Tao; Kingsley, James; Buckley, Alastair R.; Lidzey, David G.

    2015-01-01

    ABSTRACT Electron microscopy has been used to study the degradation of organic solar cells when exposed to humid air. Devices with various different combinations of commonly used organic solar cell hole transport layers and cathode materials have been investigated. In this way the ingress of water and the effect it has on devices could be studied. It was found that calcium and aluminum in the cathode both react with water, causing voids and delamination within the device. The use of poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) was found to increase the degradation by easing water ingress into the device. Replacing these materials removed these degradation features. © 2015 The Authors. Journal of Polymer Science Part B: Polymer Physics published by Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 216–224 PMID:27594763

  4. Low altitude temperature and humidity profile data for application to aircraft noise propagation

    NASA Technical Reports Server (NTRS)

    Connor, A. B.; Copeland, W. L.; Fulbright, D. C.

    1975-01-01

    A data search of the weather statistics from 11 widely dispersed geographical locations within the continental United States was conducted. The sites, located long both sea-coasts and in the interior, span the northern, southern, and middle latitudes. The weather statistics, retrieved from the records of these 11 sites, consist of two daily observations taken over a 10-year period. The data were sorted with respect to precipitation and surface winds and classified into temperature intervals of 5 C and relative humidity intervals of 10 percent for the lower 1400 meters of the atmosphere. These data were assembled in a statistical format and further classified into altitude increments of 200 meters. The data are presented as sets of tables for each site by season of the year and include both daily observations.

  5. Modeling the effect of relative humidity on nitrous acid formation in the Houston area

    NASA Astrophysics Data System (ADS)

    Diao, Lijun; Roy, Anirban; Czader, Beata; Pan, Shuai; Jeon, Wonbae; Souri, Amir Hossein; Choi, Yunsoo

    2016-04-01

    The field and laboratory based relative humidity (RH) impact on nitrous acid (HONO) heterogeneous reaction has not been considered in chemical transport models. This study parameterized this dependency into the Community Multiscale Air Quality (CMAQ) model. In view of the positive linear correlation between the reaction rate and RH, the HONO heterogeneous reaction rate constants were respectively scaled by the factors of RH/30 and RH/40. Two corresponding sensitivity tests were carried out in the period of September 2013 in Houston. Both tests significantly improved modeled HONO concentrations and reduced the bias for NO2 in comparison with observations. However, the model is still not capable of reproducing the high HONO concentrations in the morning rush hours. Further work is needed to explore the underlying mechanisms for the early morning HONO formation.

  6. Technical Consulting: The African-American Perspective

    ERIC Educational Resources Information Center

    Whitfield, Tracy N.

    2010-01-01

    The qualitative research study explored the organizational characteristics necessary in addressing the low concentration of African American technical consultants employed in the information technology industry. Using research participants' professional experience, participants responded to a developed questionnaire. African American technical…

  7. Towards an African Philosophy of Education.

    ERIC Educational Resources Information Center

    Ocaya-Lakidi, Dent

    1980-01-01

    Compares and contrasts contemporary philosophies of education in Africa with two philosophical doctrines (naturalism and idealism). Topics discussed include value selectors, westernization, the role of missionaries in African education, critical consciousness, relevance, and African education today. (DB)

  8. African N Assessment

    NASA Astrophysics Data System (ADS)

    Bekunda, M.; Galford, G. L.; Hickman, J. E.; Palm, C.

    2011-12-01

    Africa's smallholder agricultural systems face unique challenges in planning for reducing poverty, concurrent with adaptation and mitigation to climate change. At continental level, policy seeks to promote a uniquely African Green Revolution to increase crop yields and food production, and improve local livelihoods. However, the consequences on the environment and climate are not clear; these pro-economic development measures should be linked to climate change adaptation and mitigation measures, and research is required to help achieve these policy proposals by identifying options, and testing impacts. In particular, increased nitrogen (N) inputs are essential for increasing food production in Africa, but are accompanied by inevitable increases in losses to the environment. These losses appear to be low at input levels promoted in agricultural development programs, while the increased N inputs both increase current food production and appear to reduce the vulnerability of food production to changes in climate. We present field and remote sensing evidence from Malawi that subsidizing improved seed and fertilizers increases resilience to drought without adding excess N to the environment. In Kenya, field research identified thresholds in N2O losses, where emissions are very low at fertilization rates of less than 200 kg ha-1. Village-scale models have identified potential inefficiencies in the food production process where the largest losses of reactive N occur, and which could be targeted to reduce the amount of N released to the environment. We further review some on-going research activities and progress in Africa that compare different methods of managing resources that target resilience in food production and adaptation to climate change, using nutrient N as an indicator, while evaluating the effects of these resource management practices on ecosystems and the environment.

  9. Fingerprint of Seasonal Relative humidity in Rice (Oryza sativa L.): Potential for Paleoclimate Archive

    NASA Astrophysics Data System (ADS)

    Kaushal, R.; Ghosh, P.

    2015-12-01

    Seasonal variability of relative humidity (RH) condition during southwest monsoon (SWM) is strongly related with availability of moisture for rainfall over the continental region. There are ongoing efforts to reconstruct the past monsoonal condition based on geochemical and isotopic records as proxies [1]. However, limited archives have been successfully retrieved for reconstructing moisture condition during SWM [2]. Potential of plants as climate archives and the mechanism involved in transfer of climate signature to the stable isotope composition of oxygen (δ18O) has been demonstarted successfully [3]. Here we are introducing δ18O of rice grain bulk organic matter (δ18OOM) as a new proxy for precise determination of RH during SWM. Rice is a seasonal crop and widely cultivated over the Indian subcontinent during SWM. Here we present δ18OOM of rice grains collected from 15 locations from different climatic zones over the Indian subcontinent, ranging from semi-arid to humid-perhumid. These samples were collected from the harvest of the crop grown at the time of SWM for the period 2012-2014. Each of these climatic zones are characterized by unique range of RH values, which is expected to leave distinct oxygen isotopic signature in the rice grain OM. We compared the δ18OOM values with δ18O of precipitation water, RH and temperature during the period of cultivation. Precipitation δ18O values were obtained from were obtained from OPIC [4]. Our observations document a significant relationship between δ18OOM and RH (R2 =0.62, p<0.001). When the RH level fluctuated from 65% to 88%, δ18OOM tended to vary between 31.5 ‰ to 15.4‰. However, the humid regions with rainfed crop showed significant relationship between δ18OOM and precipitation δ18O. Remaining stations being fed by the both rain and irrigation from river/ groundwater, dampen the rainfall isotope signature in δ18OOM. This approach can be extended in deriving RH of regions of rice cultivation by

  10. Intensity and amplitudes of humidity during the past 900 ka at the SE Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Appel, Erwin; Hu, Shouyun; Rao Goddu, Srinivasa; Herb, Christian

    2014-05-01

    We investigate paleoclimate fluctuations during 900-30 ka at the SE Tibetan Plateau based on a high-resolution lacustrine record from Heqing basin in NW Yunnan (SW China). Multivariate statistical and time series analyses of multi-proxy data from a 168m-long drill core, mainly magnetic parameters and carbonate content, in combination with results from a catchment study, allow us to develop a scenario for explaining the parameter variation in terms of humidity changes. This scenario is based on carbonate weathering in the catchment (limestones are predominant), characteristics of soil formed on the bedrock, relative changes of sediment transport by wind and surface water, low-temperature oxidation of magnetite, and grain-size selective dissolution of ferrimagnetic particles, related to wetter and drier conditions. Cluster analysis reveals four different phases with transitions at 670-630 ka, 380-320 ka, and 80 ka. We further resolve amplitude and intensity variations of weathering by a humidity index (HI) obtained through convolution of carbonate content, the magnetic grain-size parameter ARM/SIRM, and a magnetite/hematite measure (S-ratio). Strong amplitude variations relate to 100 ka eccentricity cycles. We may explain these variations by relative stronger and weaker influence of the Indian summer monsoon (ISM) that together with the East-Asian summer monsoon (EASM) affects the region of the SE Tibetan Plateau. Stronger orbital variations are likely in periods of stronger ISM because of its inter-hemispheric driving forces. During 630-380 ka we observe the strongest eccentricity amplitudes of the HI. When the influence of the ISM in the region weakens, not only orbital amplitudes will reduce but also moisture supply becomes less. A period of prevailing drier conditions is indicated in our HI record between 320-80 ka after which the HI suggests a quick return to clearly more humid conditions. Our study emphasizes the capability of magnetic parameters for

  11. The role of groundwater in streamflow in a headwater catchment with sub-humid climate

    NASA Astrophysics Data System (ADS)

    Liu, Yaping; Tian, Fuqiang; Hu, Hongchang; Tie, Qiang

    2015-04-01

    Recent studies have suggested that bedrock groundwater can exert considerable influence on streamflow in headwater catchments under humid climate. However, study of the role of bedrock groundwater is still challenged due to limited direct observation data. In this study, by utilizing observed hydrometric and hydrochemical data, we aimed at characterize the bedrock groundwater's response to rainfall at hillslope and catchment scales in a small headwater catchment with sub-humid climate. We selected Xitaizi catchment with area of 6.7 km in the earth-rock mountain region, which located in the north of Beijing, China, as study area. The catchment bedrock is mainly consist of fractured granite. Four weather stations were installed to observe the weather condition and soil volumetric water content (VWC) at depth of 10-60 cm with 10-minute interval. Five wells with depth of 10 m were drilled in two slopes to monitor the bedrock water table by pneumatic water gauge. At slope 1, the soil VWC at depth of 10-80 cm were also observed by soil moisture sensors, and surface/subsurface hillslope runoff at three different layers (0-20cm, 20-80cm, 80-300cm) was observed by three recording buckets. Field works were conducted from July 2013 to November 2014. During the period, precipitation, river, spring and groundwater were sampled nearly monthly. Water temperature, electrical conductivity (EC) and pH were measured in site with portable instruments. In addition, the precipitation, river and groundwater were also sampled intensively during two storm events. All the samples were subjected to stable isotope analysis, the samples taken monthly during the period from July 2013 to July 2014 were subjected to hydrochemistry analysis. Our results show that: (1) the bedrock groundwater is the dominant component of streamflow in the headwater catchment with sub-humid climate; (2) stream is recharged by groundwater sourcing from different mountains with different hydrochemistry characteristics

  12. The African Cultural Astronomy Project

    NASA Astrophysics Data System (ADS)

    Urama, Johnson O.; Holbrook, Jarita C.

    2011-06-01

    Indigenous, endogenous, traditional, or cultural astronomy focuses on the many ways that people and cultures interact with celestial bodies. In most parts of Africa, there is very little or no awareness about modern astronomy. However, like ancient people everywhere, Africans wondered at the sky and struggled to make sense of it. The African Cultural Astronomy Project aims to unearth the body of traditional knowledge of astronomy possessed by peoples of the different ethnic groups in Africa and to consider scientific interpretations when appropriate for cosmogonies and ancient astronomical practices. Regardless of scientific validity, every scientist can relate to the process of making observations and creating theoretical mechanisms for explaining what is observed. Through linking the traditional and the scientific, it is believed that this would be used to create awareness and interest in astronomy in most parts of Africa. This paper discusses the vision, challenges and prospects of the African Cultural Astronomy Project in her quest to popularize astronomy in Africa.

  13. West African crude production diversifies

    SciTech Connect

    Aalund, L.

    1983-06-01

    Nigeria, with its seven crude-oil export streams, dominated West African production and accounted for over 70% of the depressed 1.8 million b/d output from the region last year. However, during the 1970s a flurry of new producing fields, primarily off the African coast, diversified production among a number of countries and touched off a wave of oil activity. The Journal takes a close look at the quality of West African oil in this installment of assays on world export crudes. This issue covers, in alphabetical order, Bonny Light (Nigeria) to Espoir (Ivory Coast). A following issue will wrap up West Africa by presenting assays on crudes from Forcados Blend (Nigeria) to Zaire Crude (Zaire).

  14. Plio-pleistocene African climate

    SciTech Connect

    deMenocal, P.B.

    1995-10-06

    Marine records of African climate variability document a shift toward more arid conditions after 2.8 million years ago (Ma), evidently resulting from remote forcing by cold North Atlantic sea-surface temperatures associated with the onset of Northern Hemisphere glacial cycles. African climate before 2.8 Ma was regulated by low-latitude insolation forcing of monsoonal climate due to Earth orbital precession. Major steps in the evolution of African hominids and other vertebrates are coincident with shifts to more arid, open conditions near 2.8 Ma, 1.7 Ma, and 1.0 Ma, suggesting that some Pliocene (Plio)-Pleistocene speciation events may have been climatically mediated. 65 refs., 6 figs.

  15. Plio-Pleistocene African Climate

    NASA Astrophysics Data System (ADS)

    Demenocal, Peter B.

    1995-10-01

    Marine records of African climate variability document a shift toward more arid conditions after 2.8 million years ago (Ma), evidently resulting from remote forcing by cold North Atlantic sea-surface temperatures associated with the onset of Northern Hemisphere glacial cycles. African climate before 2.8 Ma was regulated by low-latitude insolation forcing of monsoonal climate due to Earth orbital precession. Major steps in the evolution of African hominids and other vertebrates are coincident with shifts to more arid, open conditions near 2.8 Ma, 1.7 Ma, and 1.0 Ma, suggesting that some Pliocene (Plio)-Pleistocene speciation events may have been climatically mediated.

  16. Effects of humidity and depurination on the charge transport in DNA films

    NASA Astrophysics Data System (ADS)

    Lee, E.; Han, J. H.; Kim, D.; Jeon, G. W.; Lee, Cheol Eui; Park, Y. J.; Kim, H. D.; Kim, J.

    2015-01-01

    We have investigated the humidity and depurination (creating apurinic sites) effects on the electrical conduction in the λ-DNA films at different relative humidities and depurination times. The DNA films were found to follow the polaron hopping model, and the polaron hopping distance turned out to decrease at the higher relative humidity, more water molecules supposedly being adsorbed on the film. The activation energy showed little dependence on the depurination time at the higher relative humidity, whereas at the lower humidity it increased sharply with increasing depurination time.

  17. Biologically inspired humidity sensor based on three-dimensional photonic crystals

    NASA Astrophysics Data System (ADS)

    Kim, Jae Hyun; Moon, Jun Hyuk; Lee, Seung-Yop; Park, Jungyul

    2010-09-01

    This letter presents a biomimetic humidity sensor inspired by the humidity-dependent color change observed in the cuticle of the Hercules beetle. A thin-film-type humidity sensor with nanoporous structures (three-dimensional photonic crystals) mimicking the spongy multilayer in the beetles was designed and fabricated using the colloidal templating method and a hydrophilic surface treatment. The visible color of the fabricated humidity sensor changes from blue-green to red as the environmental humidity increases. The wavelength of reflected light that is predicted by Bragg's equation considering the effect of water absorption shows a good agreement with experimental results.

  18. Reconstruction of late Quaternary relative humidity changes on the southern slopes of Mt. Kilimanjaro, East Africa, using a coupled δ2H-δ18O biomarker paleohygrometer

    NASA Astrophysics Data System (ADS)

    Hepp, Johannes; Zech, Roland; Rozanski, Kazimierz; Tuthorn, Mario; Glaser, Bruno; Greule, Markus; Keppler, Frank; Huang, Yongsong; Zech, Wolfgang; Zech, Michael

    2016-04-01

    Our understanding of African paleoclimate/-hydrological history is decisively based on lake level and lake sediment studies. It furthermore improved remarkably during the last decade thanks to emerging stable isotope techniques such as compound-specific deuterium analysis of sedimentary leaf wax biomarkers (δ2Hleaf wax). Here we present results from a multi-proxy biomarker study carried out on a ~100 ka paleosol sequence developed in the Maundi crater at ~2780 m a.s.l. on the southeastern slopes of Mt. Kilimanjaro in equatorial East Africa. The Maundi stable isotope records established for hemicellulose-derived sugars, lignin- and pectin-derived methoxyl groups and leaf wax-derived fatty acid and n-alkane biomarkers (δ18Osugars, δ2Hmethoxyl groups, δ2Hfatty acids and δ2Hn‑alkanes) reveal differences but also similar patterns. Maxima characterize the period from 70 to 60 ka, the last glacial maximum (LGM) and the Younger Dryas (YD), whereas minima occur during the Holocene. The application of a 'coupled δ2Hn‑alkane-δ18Osugar paleohygrometer' allows the reconstruction of the Late Quaternary relative humidity (RH) history of the Maundi study site. Accordingly, the reconstructed RH changes are well in agreement with the Maundi pollen results. Apart from the overall regional moisture availability, the intensification versus weakening of the trade wind inversion, which affects the diurnal montane atmospheric circulation on the slopes of Mt. Kilimanjaro, is suggested as local second important factor controlling the RH history at Maundi. Furthermore, the Maundi results of the coupled δ2Hn‑alkane-δ18Osugar approach caution against interpreting δ2Hleaf wax (as well as δ18Osugar) records straight forwards in terms of reflecting δ2Hprec, because variably and primarily RH-dependent isotopic evapotranspirative enrichment of leaf water can mask δ2Hprec changes. Concerning the biomarker-based reconstructed Maundi δ2H/δ18Oprec record, the comparison with the

  19. The genomic substrate for adaptive radiation in African cichlid fish

    PubMed Central

    Malinsky, Milan; Keller, Irene; Fan, Shaohua; Simakov, Oleg; Ng, Alvin Y.; Lim, Zhi Wei; Bezault, Etienne; Turner-Maier, Jason; Johnson, Jeremy; Alcazar, Rosa; Noh, Hyun Ji; Russell, Pamela; Aken, Bronwen; Alföldi, Jessica; Amemiya, Chris; Azzouzi, Naoual; Baroiller, Jean-François; Barloy-Hubler, Frederique; Berlin, Aaron; Bloomquist, Ryan; Carleton, Karen L.; Conte, Matthew A.; D'Cotta, Helena; Eshel, Orly; Gaffney, Leslie; Galibert, Francis; Gante, Hugo F.; Gnerre, Sante; Greuter, Lucie; Guyon, Richard; Haddad, Natalie S.; Haerty, Wilfried; Harris, Rayna M.; Hofmann, Hans A.; Hourlier, Thibaut; Hulata, Gideon; Jaffe, David B.; Lara, Marcia; Lee, Alison P.; MacCallum, Iain; Mwaiko, Salome; Nikaido, Masato; Nishihara, Hidenori; Ozouf-Costaz, Catherine; Penman, David J.; Przybylski, Dariusz; Rakotomanga, Michaelle; Renn, Suzy C. P.; Ribeiro, Filipe J.; Ron, Micha; Salzburger, Walter; Sanchez-Pulido, Luis; Santos, M. Emilia; Searle, Steve; Sharpe, Ted; Swofford, Ross; Tan, Frederick J.; Williams, Louise; Young, Sarah; Yin, Shuangye; Okada, Norihiro; Kocher, Thomas D.; Miska, Eric A.; Lander, Eric S.; Venkatesh, Byrappa; Fernald, Russell D.; Meyer, Axel; Ponting, Chris P.; Streelman, J. Todd; Lindblad-Toh, Kerstin; Seehausen, Ole; Di Palma, Federica

    2015-01-01

    Cichlid fishes are famous for large, diverse and replicated adaptive radiations in the Great Lakes of East Africa. To understand the molecular mechanisms underlying cichlid phenotypic diversity, we sequenced the genomes and transcriptomes of five lineages of African cichlids: the Nile tilapia (Oreochromis niloticus), an ancestral lineage with low diversity; and four members of the East African lineage: Neolamprologus brichardi/pulcher (older radiation, Lake Tanganyika), Metriaclima zebra (recent radiation, Lake Malawi), Pundamilia nyererei (very recent radiation, Lake Victoria), and Astatotilapia burtoni (riverine species around Lake Tanganyika). We found an excess of gene duplications in the East African lineage compared to tilapia and other teleosts, an abundance of non-coding element divergence, accelerated coding sequence evolution, expression divergence associated with transposable element insertions, and regulation by novel microRNAs. In addition, we analysed sequence data from sixty individuals representing six closely related species from Lake Victoria, and show genome-wide diversifying selection on coding and regulatory variants, some of which were recruited from ancient polymorphisms. We conclude that a number of molecular mechanisms shaped East African cichlid genomes, and that amassing of standing variation during periods of relaxed purifying selection may have been important in facilitating subsequent evolutionary diversification. PMID:25186727

  20. PUBLISHING SOUTH AFRICAN SCHOLARSHIP IN THE GLOBAL ACADEMIC COMMUNITY.

    PubMed

    Le Roux, Elizabeth

    2015-09-20

    South Africa's academic publishing history has been profoundly influenced by its colonial heritage. This is reflected in the publication of Transactions of the South African Philosophical Society (later, the Royal Society of South Africa) from 1878. Although the Society and journal sought to promote original research about South Africa, it was modelled after the Royal Society in London and formed part of an imperial scientific community. As the local higher education institutions grew more independent and research-focused, local scholarly publishing developed as well, with university presses playing an increasingly important role. The University of South Africa (Unisa) Press started publishing departmental journals in the 1950s, with a focus on journals that 'speak to the student', and it is today the only South African university press with an active journals publishing programme. As external funding declined and the country became intellectually isolated in the high apartheid period, the Press managed to attract journals that could no longer be subsidized by learned societies and other universities. More recently, new co-publishing arrangements have brought South African journals back into an international intellectual community. Although some argue that this constitutes a re-colonization of South African knowledge production, it is also an innovative strategy for positioning local research in a global context. PMID:26495579