6,786 research outputs found
Homoeopathy
Homoeopathy is a system of treating patients
using very low dose preparations according
to the principle: "like should be cured with
like". This paper summarises the research evidence
presented in a recent issue of Effective Health
Care on the effectiveness of homoeopathy.
Increasing numbers of patients are seeking
information on complementary medicines from
NHS health professionals. Results of a 1998 survey
of use and expenditure on complementary
medicine in England suggested that 28% of
respondents had either visited a complementary
therapist or had purchased an over the counter
herbal or homoeopathic remedy in the past year.
From this survey it was estimated that there
could be over 470 000 recent users of homoeopathic
remedies in England
Early CRT monitoring using time-domain optical coherence tomography does not add to visual acuity for predicting visual loss in patients with central retinal vein occlusion treated with intravitreal ranibizumab:A secondary analysis of trial data
Our primary purpose was to assess the clinical (predictive) validity of central retinal thickness (CRT) and best corrected visual acuity (BCVA) at 1 week and 1 month after starting treatment with ranibizumab for central retinal vein occlusion. The authors also assessed detectability of response to treatment
Chromospheric CaII Emission in Nearby F, G, K, and M stars
We present chromospheric CaII activity measurements, rotation periods and
ages for ~1200 F-, G-, K-, and M- type main-sequence stars from ~18,000
archival spectra taken at Keck and Lick Observatories as a part of the
California and Carnegie Planet Search Project. We have calibrated our
chromospheric S values against the Mount Wilson chromospheric activity data.
From these measurements we have calculated median activity levels and derived
R'HK, stellar ages, and rotation periods for 1228 stars, ~1000 of which have no
previously published S values. We also present precise time series of activity
measurements for these stars.Comment: 62 pages, 7 figures, 1 table. Second (extremely long) table is
available at http://astro.berkeley.edu/~jtwright/CaIIdata/tab1.tex Accepted
by ApJ
Hubble Space Telescope High Resolution Imaging of Kepler Small and Cool Exoplanet Host Stars
High resolution imaging is an important tool for follow-up study of exoplanet
candidates found via transit detection with the Kepler Mission. We discuss here
HST imaging with the WFC3 of 23 stars that host particularly interesting Kepler
planet candidates based on their small size and cool equilibrium temperature
estimates. Results include detections, exclusion of background stars that could
be a source of false positives for the transits, and detection of
physically-associated companions in a number of cases providing dilution
measures necessary for planet parameter refinement. For six KOIs, we find that
there is ambiguity in which star hosts the transiting planet(s), with
potentially strong implications for planetary characteristics. Our sample is
evenly distributed in G, K, and M spectral types. Albeit with a small sample
size, we find that physically-associated binaries are more common than expected
at each spectral type, reaching a factor of 10 frequency excess at M. We
document the program detection sensitivities, detections, and deliverables to
the Kepler follow-up program archive.Comment: Accepted for the Astronomical Journal; 13 pages with 9 figure
Gas flow in near surface comet like porous structures: Application to 67P/Churyumov-Gerasimenko
We performed an investigation of a comet like porous surface to study how sub-surface sublimation with subsequent flow through the porous medium can lead to higher gas temperatures at the surface. A higher gas temperature of the emitted gas at the surface layer, compared to the sublimation temperature, will lead to higher gas speeds as the gas expands into the vacuum thus altering the flow properties on larger scales (kilometres away from the surface). Unlike previous models that have used modelled artificial structures, we used Earth rock samples with a porosity in the range 24 – 92 % obtained from X-ray micro computed tomography (micro-CT) scans with resolution of some μm. Micro-CT scanning technology provides 3D images of the pore samples. The direct simulation Monte Carlo (DSMC) method for the rarefied gas dynamics is directly applied on the digital rock samples in an unstructured mesh to determine the gas densities, temperatures and speeds within the porous medium and a few centimetres above the surface. The thicknesses of the rock samples were comparable to the diurnal thermal skin depth (5cm). H2O was assumed to be the outgassing species. We correlated the coma temperatures and other properties of the flow with the rock porosities. The results are discussed as an input to analysis of data from the Microwave Instrument on Rosetta Orbiter (MIRO) on the 67P/Churyumov-Gerasimenko
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A Method for Accurate Transmission Line Impedance Parameter Estimation
Real-time estimation of power transmission line impedance parameters has become possible with the availability of synchronized phasor (synchrophasor) measurements of voltage and current. If sufficiently accurate, the estimated parameter values are a powerful tool for improving the performance of a range of power system monitoring, protection, and control applications, including fault location and dynamic thermal line rating. The accuracy of the parameter estimates can be reduced by unknown errors in the synchrophasors that are introduced in the measurement process. In this paper, a method is proposed with the aim of obtaining accurate estimates of potentially variable impedance parameters, in the presence of systematic errors in voltage and current measurements. The method is based on optimization to identify correction constants for the phasors. A case study of a simulated transmission line is presented to demonstrate the effectiveness of the new method, which is better in comparison with a previously proposed method. The results, as well as limits, and the potential extensions of the new method are discussed
Evidence for a Molecular Cloud Origin for Gamma-Ray Bursts: Implications for the Nature of Star Formation in the Universe
It appears that the majority of rapidly-, well-localized gamma-ray bursts
with undetected, or dark, optical afterglows, or `dark bursts' for short, occur
in clouds of size R > 10L_{49}^{1/2} pc and mass M > 3x10^5L_{49} M_{sun},
where L is the isotropic-equivalent peak luminosity of the optical flash. We
show that clouds of this size and mass cannot be modeled as a gas that is bound
by pressure equilibrium with a warm or hot phase of the interstellar medium
(i.e., a diffuse cloud): Such a cloud would be unstable to gravitational
collapse, resulting in the collapse and fragmentation of the cloud until a
burst of star formation re-establishes pressure equilibrium within the
fragments, and the fragments are bound by self-gravity (i.e., a molecular
cloud). Consequently, dark bursts probably occur in molecular clouds, in which
case dark bursts are probably a byproduct of this burst of star formation if
the molecular cloud formed recently, and/or the result of lingering or latter
generation star formation if the molecular cloud formed some time ago. We then
show that if bursts occur in Galactic-like molecular clouds, the column
densities of which might be universal, the number of dark bursts can be
comparable to the number of bursts with detected optical afterglows: This is
what is observed, which suggests that the bursts with detected optical
afterglows might also occur in molecular clouds. We confirm this by modeling
and constraining the distribution of column densities, measured from absorption
of the X-ray afterglow, of the bursts with detected optical afterglows: We find
that this distribution is consistent with the expectation for bursts that occur
in molecular clouds, and is not consistent with the expectation for bursts that
occur in diffuse clouds. More...Comment: Accepted to The Astrophysical Journal, 22 pages, 6 figures, LaTe
Fourteen New Companions from the Keck & Lick Radial Velocity Survey Including Five Brown Dwarf Candidates
We present radial velocities for 14 stars on the California & Carnegie Planet
Search target list that reveal new companions. One star, HD 167665, was fit
with a definitive Keplerian orbit leading to a minimum mass for the companion
of 50.3 Mjup at a separation from its host of ~5.5 AU. Incomplete or limited
phase coverage for the remaining 13 stars prevents us from assigning to them
unique orbital parameters. Instead, we fit their radial velocities with
Keplerian orbits across a grid of fixed values for Msini and period, P, and use
the resulting reduced chi-square surface to place constraints on Msini, P, and
semimajor axis, a. This technique allowed us to restrict Msini below the brown
dwarf -- stellar mass boundary for an additional 4 companions (HD 150554, HD
8765, HD 72780, HD 74014). If the combined 5 companions are confirmed as brown
dwarfs, these results would comprise the first major catch of such objects from
our survey beyond ~3 AU.Comment: 29 pages, 14 figures, accepted to Ap
The Lick-Carnegie Survey: Four New Exoplanet Candidates
We present new precise HIRES radial velocity (RV) data sets of five nearby
stars obtained at Keck Observatory. HD 31253, HD 218566, HD 177830, HD 99492
and HD 74156 are host stars of spectral classes F through K and show radial
velocity variations consistent with new or additional planetary companions in
Keplerian motion. The orbital parameters of the candidate planets in the five
planetary systems span minimum masses of M sin i = 27.43 M_{earth} to M sin i =
8.28 M_{jup}, periods of 17.05 to 4696.95 days and eccentricities ranging from
circular to extremely eccentric (e ~ 0.63). The 5th star, HD 74156, was known
to have both a 52-day and a 2500-day planet, and was claimed to also harbor a
3rd planet at 336d, in apparent support of the "Packed Planetary System"
hypothesis. Our greatly expanded data set for HD 74156 provides strong
confirmation of both the 52-day and 2500-d planets, but strongly contradicts
the existence of a 336-day planet, and offers no significant evidence for any
other planets in the system.Comment: 13 pages, 15 figures. Accepted for publication in ApJ. Fixed typos in
Table 2. Additional material at http://www.ucolick.org/~smeschia/4planet.ph
Profile of Corporate Social Media Consumer Segments
The trade and academic literature is replete with commentary about the need for companies to develop promotional strategies and to adopt media platforms that are more engaging and conversational with customers than the traditional top-down company directed one-way communication strategies of the past (Thomas, Peters, Howell and Robbins, 2012; Foster, West and Francescucci 2011; Deighton and Kornfeld, 2009). This viewpoint is supported by Christodoulides (2008) who reported that many customers view information about a company or brand that they obtained from blogs, social networking sites and the like as being more relevant, believable and important to them in their interactions with the company than similar company provided information. Social media savvy customers are by all counts a highly diverse lot and reaching them effectively requires the use of different messages for different groups (Heo and Cho, 2009; Stern, Rao and Gould 1990). For example, some social media users follow a wide variety of posts and enjoy the benefits of special offers while others have mixed feelings about being marketed to on social media websites. Interestingly, this new brand of customer also expects businesses to really know them, their life cycles, their personalities and the goods and services that they desire (Beauchamp 2013)
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