133 research outputs found
Bowling alone but tweeting together: the evolution of human interaction in the social networking era
The objective of this paper is to theoretically analyze how human interaction may evolve in a world characterized by the explosion of online networking and other Web-mediated ways of building and nurturing relationships. The analysis shows that online networking yields a storage mechanism through which any individual contribution—e.g. a blog post, a comment, or a photo—is stored within a particular network and ready for virtual access by each member who connects to the network. When someone provides feedback, for example by commenting on a note, or by replying to a message, the interaction is finalized. These interactions are asynchronous, i.e. they allow individuals to relate in different moments, whenever they have time to. When the social environment is poor of participation opportunities and/or the pressure on time increases (for example due to the need to increase the working time), the stock of information and ties stored in the Internet can help individuals to defend their sociability
Electron Mobility and Magneto Transport Study of Ultra-Thin Channel Double-Gate Si MOSFETs
We report on detailed room temperature and low temperature transport
properties of double-gate Si MOSFETs with the Si well thickness in the range
7-17 nm. The devices were fabricated on silicon-on-insulator wafers utilizing
wafer bonding, which enabled us to use heavily doped metallic back gate. We
observe mobility enhancement effects at symmetric gate bias at room
temperature, which is the finger print of the volume inversion/accumulation
effect. An asymmetry in the mobility is detected at 300 K and at 1.6 K between
the top and back interfaces of the Si well, which is interpreted to arise from
different surface roughnesses of the interfaces. Low temperature peak
mobilities of the reported devices scale monotonically with Si well thickness
and the maximum low temperature mobility was 1.9 m2/Vs, which was measured from
a 16.5 nm thick device. In the magneto transport data we observe single and two
sub-band Landau level filling factor behavior depending on the well thickness
and gate biasing
Major threats caused by climate change to grapevine
The main worrying feature of climate change is its rapid evolution, in extent and variation, becoming less and less predictable. In this paper, we have reviewed the available literature and elaborated original data to outline how climate change will affect the grapevine cultivation and wine quality. We start by discussing which features of climate change will impact grapevine production most. The effects of heatwaves, air and soil temperature, extreme rainfall events, atmospheric evaporative demand, wildfires, and smoke are addressed. An increased frequency and intensity of heat waves since 2010 is shown in four grapevine production areas of Northern Italy. The focus then shifts to the impacts of the predicted increase in temperature and drought on frost risks, grapevine phenology, yield, berry quality and water needs as well as vine and vineyard carbon budgets. Climate change will challenge the achievement of current yields and wine quality as well as the ability of vineyards to sequester atmospheric carbon, but such effects will likely depend on the characteristics of the growing environments and on the varieties present. Climate change-related threats to grapevine call for a rapid implementation of adaptation strategies
CYTOCHROME P450 3A13 AND ENDOTHELIN JOINTLY MEDIATE DUCTUS ARTERIOSUS CONSTRICTION TO OXYGEN IN MICE
The fetal ductus arteriosus (DA) contracts to oxygen, and this feature, maturing through gestation, is considered important for its closure at birth. We have previously obtained evidence of the involvement of cytochrome P-450, possibly of the 3A subfamily (CYP3A), in oxygen sensing and have also identified endothelin (ET)-1 as the attendant effector for the contraction. Here, we examined comparatively wild-type (WT) and CYP3Anull (Cyp3a(-/-)) mice for direct validation of this concept. We found that the CYP3A subfamily is represented only by CYP3A13 in the WT DA. CYP3A13 was also detected in the DA by immunofluorescence microscopy, being primarily colocalized with the endoplasmic reticulum in both endothelial and muscle cells. However, a distinct signal was also evident in the plasma membrane. Isolated DAs from term WT animals developed a sustained contraction to oxygen with transient contractions superimposed. Conversely, no tonic response occurred in Cyp3a(-/-) DAs, whereas the phasic response persisted unabated. Oxygen did not contract the preterm WT DA but caused a full-fledged contraction after retinoic acid (RA) treatment. RA also promoted an oxygen contraction in the Cyp3a(-/-) DA. However, responses of RA-treated WT and Cyp3a(-/-) mice differed in that only the former abated with ET-1 suppression. This implies the existence of an alternative target for RA responsible for the oxygen-induced contraction in the absence of CYP3A13. In vivo, the DA was constricted in WT and Cyp3a(-/-) newborns, although with a tendency to be less narrowed in the mutant. We conclude that oxygen acts primarily through the complex CYP3A13 (sensor)/ET-1 (effector) and, in an accessory way, directly onto ET-1. However, even in the absence of CYP3A13, the DA may close postnatally thanks to the contribution of ET-1 and the likely involvement of compensating mechanism(s) identifiable with an alternative oxygen-sensing system and/or the withdrawal of relaxing influence(s) operating prenatally
Synchrotron Radiation Micro-tomography:a non Destructive tool for the Characterization of Archaeological Wood
Online and Offline Social Participation and Social Poverty Traps: Can Social Networks Save Human Relations?
XQR-30: The ultimate XSHOOTER quasar sample at the reionization epoch
The final phase of the reionization process can be probed by rest-frame UV absorption spectra of quasars at z ≳ 6, shedding light on the properties of the diffuse intergalactic medium within the first Gyr of the Universe. The ESO Large Programme 'XQR-30: the ultimate XSHOOTER legacy survey of quasars at z ≃ 5.8-6.6' dedicated ∼250 h of observations at the VLT to create a homogeneous and high-quality sample of spectra of 30 luminous quasars at z ∼6, covering the rest wavelength range from the Lyman limit to beyond the Mg ii emission. Twelve quasar spectra of similar quality from the XSHOOTER archive were added to form the enlarged XQR-30 sample, corresponding to a total of ∼350 h of on-source exposure time. The median effective resolving power of the 42 spectra is R ≃ 11 400 and 9800 in the VIS and NIR arm, respectively. The signal-to-noise ratio per 10 km s-1 pixel ranges from ∼11 to 114 at λ ≃ 1285 Å rest frame, with a median value of ∼29. We describe the observations, data reduction, and analysis of the spectra, together with some first results based on the E-XQR-30 sample. New photometry in the H and K bands are provided for the XQR-30 quasars, together with composite spectra whose characteristics reflect the large absolute magnitudes of the sample. The composite and the reduced spectra are released to the community through a public repository, and will enable a range of studies addressing outstanding questions regarding the first Gyr of the Universe
XQR-30: the ultimate XSHOOTER quasar sample at the reionization epoch
The final phase of the reionization process can be probed by rest-frame UV
absorption spectra of quasars at z>6, shedding light on the properties of the
diffuse intergalactic medium within the first Gyr of the Universe. The ESO
Large Programme "XQR-30: the ultimate XSHOOTER legacy survey of quasars at
z~5.8-6.6" dedicated ~250 hours of observations at the VLT to create a
homogeneous and high-quality sample of spectra of 30 luminous quasars at z~6,
covering the rest wavelength range from the Lyman limit to beyond the MgII
emission. Twelve quasar spectra of similar quality from the XSHOOTER archive
were added to form the enlarged XQR-30 sample, corresponding to a total of ~350
hours of on-source exposure time. The median effective resolving power of the
42 spectra is R~11400 and 9800 in the VIS and NIR arm, respectively. The
signal-to-noise ratio per 10 km/s pixel ranges from ~11 to 114 at \AA rest frame, with a median value of ~29. We describe the
observations, data reduction and analysis of the spectra, together with some
first results based on the E-XQR-30 sample. New photometry in the H and K bands
are provided for the XQR-30 quasars, together with composite spectra whose
characteristics reflect the large absolute magnitudes of the sample. The
composite and the reduced spectra are released to the community through a
public repository, and will enable a range of studies addressing outstanding
questions regarding the first Gyr of the Universe.Comment: 21 pages, 10 figures. Revised version resubmitted to MNRAS after
minor referee repor
Custom Integrated Circuits
Contains table of contents for Part III, table of contents for Section 1 and reports on eleven research projects.IBM CorporationMIT School of EngineeringNational Science Foundation Grant MIP 94-23221Defense Advanced Research Projects Agency/U.S. Army Intelligence Center Contract DABT63-94-C-0053Mitsubishi CorporationNational Science Foundation Young Investigator Award Fellowship MIP 92-58376Joint Industry Program on Offshore Structure AnalysisAnalog DevicesDefense Advanced Research Projects AgencyCadence Design SystemsMAFET ConsortiumConsortium for Superconducting ElectronicsNational Defense Science and Engineering Graduate FellowshipDigital Equipment CorporationMIT Lincoln LaboratorySemiconductor Research CorporationMultiuniversity Research IntiativeNational Science Foundatio
Bowling alone but tweeting together: the evolution of human interaction in the social networking era
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