Institutional Work and Artifact Evolution

How artifacts come to persist is a neglected area in organizational theory. In IS, Lucas et al. (2007) stress implementation research that takes the long view, but little is known about maintenance practices. Using Lawrence et al. (2009) institutional work framework, we analyze stakeholder efforts to stabilize and now maintain the Urban-net, a broadband network. We track it from inception through design stabilization to post-stabilization. Empirically, we add to research on the neglected area of maintenance work. Re: theory, our contributions are two-fold. First, we distinguish artifact stabilization from maintenance, a distinction Lawrence et al. (2009) ignore. Bijker’s (1997) idea of stabilization offers a way to think about the two. The temporal and relational scope of the effort involved, we show, can be different. Second, we adapt the term gardening from Olsen (2003) to characterize the multi-stranded nature of maintenance, involving efforts to preserve while also amending the Urban-net

Observed Responses of Mesospheric Water Vapor to Solar Cycle and Dynamical Forcings

This study focuses on responses of mesospheric water vapor (H2O) to the solar cycle flux at Lyman- wavelength and to wave forcings according to the multivariate ENSO index (MEI). The zonal-averaged responses are for latitudes from 60S to 60N and pressure-altitudes from 0.01 to 1.0 hPa, as obtained by multiple linear regression (MLR) analyses of time series of H2O from the Halogen Occultation Experiment (HALOE) for July 1992 to November 2005. The solar responses change from strong negative H2O values in the upper mesosphere to very weak, positive values in the tropical lower mesosphere. Those response profiles at the low latitudes agree reasonably with published results for H2O from the Microwave Limb Sounder (MLS). The distribution of seasonal H2O amplitudes corresponds well with that for temperature and is in accord with the seasonal net circulation. In general, the responses of H2O to MEI are anti-correlated with those of temperature. H2O responses to MEI are negative in the upper mesosphere and largest in the northern hemisphere; responses in the lower mesosphere are more symmetric with latitude. The H2O trends from MLR for the lower mesosphere agree with those reported from time series of microwave observations at two ground-based network stations

Environmental Studies: Bottlenecks and Prosperities

The environmentalists of the entire world are crying by forecasting the depletion of biotic and abiotic resources at an accelerating rate which may make the survival of life on earth questionable. The main cause of this disastrous degradation is due to unmindful anthropogenic activities. The present generation is unaware of consequences of environmental degradation and the need for the conservation of species and their habitats. It is an imperative need and responsibility to inculcate the culture of loving and living with nature among the youth. The University Grants Commission as per the directions of the Honourable Supreme Court of India directed all the Universities and Colleges to include Environmental Studies course in the curriculum. Accordingly, all the institutions have introduced this course in their curriculum. Nevertheless, there are several constrains in teaching this course to all students in letter and spirit of the law. Though there are certain constrains, there is scope for the enhancement of teaching and learning efficacy. This paper briefly describes the need for the introduction of the course, challenges in teaching and possible solutions

Intercomparisons of Aura MLS, ACE, and HALOE Observations of Long-Lived Trace Species Using the Langley Lagrangian Chemistry and Transport Model

We use the LaRC Lagrangian Chemistry and Transport Model (LCTM) [Considine et al., 2007; Pierce et al., 2003] to intercompare ACE, Aura, and HALOE observations of long-lived trace species. The LCTM calculates the transport, mixing, and photochemical evolution of an ensemble of parcels that have been initialized from ACE-FTS measurements. Here we focus on late November, 2004 comparisons, due to the previous 3-week period of continuous HALOE observations and MLS v2.2 data on November 29, 2004

Residual temperature bias effects in stratospheric species distributions from LIMS

The Nimbus 7 Limb Infrared Monitor of the Stratosphere (LIMS) instrument operated from 25&nbsp;October&nbsp;1978 through 28&nbsp;May&nbsp;1979. Its version 6 (V6) profiles were processed and archived in 2002. We present several diagnostic examples of the quality of the V6 stratospheric species distributions based on their level 3 zonal Fourier coefficient products. In particular, we show that there are small differences in the ascending (A) minus descending (D) orbital temperature&ndash;pressure or T(p) profiles (their A&minus;D values) that affect (A&minus;D) species values. Systematic A&minus;D biases in T(p) can arise from small radiance biases and/or from viewing anomalies along orbits. There can also be (A&minus;D) differences in T(p) due to not resolving and correcting for all of the atmospheric temperature gradient along LIMS tangent view-paths. An error in T(p) affects species retrievals through (1) the Planck blackbody function in forward calculations of limb radiance that are part of the iterative retrieval algorithm of LIMS, and (2) the registration of the measured LIMS species radiance profiles in pressure altitude, mainly for the lower stratosphere. There are clear A&minus;D differences for ozone, H2O, and HNO3 but not for NO2. Percentage differences are larger in the lower stratosphere for ozone and H2O because those species are optically thick. We evaluate V6 ozone profile biases in the upper stratosphere with the aid of comparisons against a monthly climatology of UV&ndash;ozone soundings from rocketsondes. We also provide results of time series analyses of V6 ozone, H2O, and potential vorticity for the middle stratosphere to show that their average (A+D) V6 level 3 products provide a clear picture of the evolution of those tracers during Northern Hemisphere winter. We recommend that researchers use the average V6 level 3 product for their science studies of stratospheric ozone and H2O, while keeping in mind that there are uncorrected nonlocal thermodynamic equilibrium effects in daytime ozone in the lower mesosphere and in daytime H2O in the uppermost stratosphere. We also point out that the present-day Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) experiment provides measurements and retrievals of temperature and ozone that are nearly free of anomalous diurnal variations and of effects from gradients at low and middle latitudes. &nbsp;</p

Intercomparison of Martian Lower Atmosphere Simulated Using Different Planetary Boundary Layer Parameterization Schemes

We use the mesoscale modeling capability of Mars Weather Research and Forecasting (MarsWRF) model to study the sensitivity of the simulated Martian lower atmosphere to differences in the parameterization of the planetary boundary layer (PBL). Characterization of the Martian atmosphere and realistic representation of processes such as mixing of tracers like dust depend on how well the model reproduces the evolution of the PBL structure. MarsWRF is based on the NCAR WRF model and it retains some of the PBL schemes available in the earth version. Published studies have examined the performance of different PBL schemes in NCAR WRF with the help of observations. Currently such assessments are not feasible for Martian atmospheric models due to lack of observations. It is of interest though to study the sensitivity of the model to PBL parameterization. Typically, for standard Martian atmospheric simulations, we have used the Medium Range Forecast (MRF) PBL scheme, which considers a correction term to the vertical gradients to incorporate nonlocal effects. For this study, we have also used two other parameterizations, a non-local closure scheme called Yonsei University (YSU) PBL scheme and a turbulent kinetic energy closure scheme called Mellor- Yamada-Janjic (MYJ) PBL scheme. We will present intercomparisons of the near surface temperature profiles, boundary layer heights, and wind obtained from the different simulations. We plan to use available temperature observations from Mini TES instrument onboard the rovers Spirit and Opportunity in evaluating the model results

Role of apoptotic hepatocytes in HCV dissemination: regulation by acetaldehyde

Alcohol consumption exacerbates hepatitis C virus (HCV) pathogenesis and promotes disease progression, although the mechanisms are not quite clear. We have previously observed that acetaldehyde (Ach) continuously produced by the acetaldehyde-generating system (AGS), temporarily enhanced HCV RNA levels, followed by a decrease to normal or lower levels, which corresponded to apoptosis induction. Here, we studied whether Ach-induced apoptosis caused depletion of HCV-infected cells and what role apoptotic bodies (AB) play in HCV-alcohol crosstalk. In liver cells exposed to AGS, we observed the induction of miR-122 and miR-34a. As miR-34a has been associated with apoptotic signaling and miR-122 with HCV replication, these findings may suggest that cells with intensive viral replication undergo apoptosis. Furthermore, when AGS-induced apoptosis was blocked by a pan-caspase inhibitor, the expression of HCV RNA was not changed. AB from HCV-infected cells contained HCV core protein and the assembled HCV particle that infect intact hepatocytes, thereby promoting the spread of infection. In addition, AB are captured by macrophages to switch their cytokine profile to the proinflammatory one. Macrophages exposed to HCV+ AB expressed more IL-1β, IL-18, IL-6, and IL-10 mRNAs compared with those exposed to HCV-AB. The generation of AB from AGS-treated HCV-infected cells even enhanced the induction of aforementioned cytokines. We conclude that HCV and alcohol metabolites trigger the formation of AB containing HCV particles. The consequent spread of HCV to neighboring hepatocytes via infected AB, as well as the induction of liver inflammation by AB-mediated macrophage activation potentially exacerbate the HCV infection course by alcohol and worsen disease progression

Precipitating Electrons: Evidence For Effects On Mesospheric Odd Nitrogen

Observations of electron fluxes made by the PET and LICA instruments aboard SAMPEX have been used with NO measurements made by HALOE aboard UARS to provide evidence of mesospheric and lower thermospheric NO formation due to precipitating electrons. Results indicate significant NO increases from 70 to 120 km which are associated with the occurrence of enhanced electron populations in the outer trapping regions of the magnetosphere, 2.5 ≤ L ≤ 7, which precipitate into the atmosphere