943 research outputs found
Rural to Urban Migration and Changes in Cardiovascular risk Factors in Tanzania: A Prospective Cohort Study.
High levels of rural to urban migration are a feature of most African countries. Our aim was to investigate changes, and their determinants, in cardiovascular risk factors on rural to urban migration in Tanzania. Men and women (15 to 59 years) intending to migrate from Morogoro rural region to Dar es Salaam for at least 6 months were identified. Measurements were made at least one week but no more than one month prior to migration, and 1 to 3 monthly after migration. Outcome measures included body mass index, blood pressure, fasting lipids, and self reported physical activity and diet. One hundred and three men, 106 women, mean age 29 years, were recruited and 132 (63.2%) followed to 12 months. All the figures presented here refer to the difference between baseline and 12 months in these 132 individuals. Vigorous physical activity declined (79.4% to 26.5% in men, 37.8% to 15.6% in women, p < 0.001), and weight increased (2.30 kg men, 2.35 kg women, p < 0.001). Intake of red meat increased, but so did the intake of fresh fruit and vegetables. HDL cholesterol increased in men and women (0.24, 0.25 mmoll-1 respectively, p < 0.001); and in men, not women, total cholesterol increased (0.42 mmoll-1, p = 0.01), and triglycerides fell (0.31 mmoll-1, p = 0.034). Blood pressure appeared to fall in both men and women. For example, in men systolic blood pressure fell by 5.4 mmHg, p = 0.007, and in women by 8.6 mmHg, p = 0.001. The lower level of physical activity and increasing weight will increase the risk of diabetes and cardiovascular disease. However, changes in diet were mixed, and may have contributed to mixed changes in lipid profiles and a lack of rise in blood pressure. A better understanding of the changes occurring on rural to urban migration is needed to guide preventive measures
A Link between Prompt Optical and Prompt Gamma-Ray Emission in Gamma-Ray Bursts
The prompt optical emission that arrives with gamma-rays from a cosmic
gamma-ray burst (GRB) is a signature of the engine powering the burst, the
properties of the ultra-relativistic ejecta of the explosion, and the ejecta's
interactions with the surroundings. Until now, only GRB 990123 had been
detected at optical wavelengths during the burst phase. Its prompt optical
emission was variable and uncorrelated with the prompt gamma-ray emission,
suggesting that the optical emission was generated by a reverse shock arising
from the ejecta's collision with the surrounding material. Here we report
prompt optical emission from GRB 041219a. It is variable and correlated with
the prompt gamma-rays, indicating a common origin for the optical light and the
gamma-rays. Within the context of the standard fireball model of GRBs, we
attribute this new optical component to internal shocks driven into the burst
ejecta by variations of the inner engine. The correlated optical emission is a
direct probe of the jet isolated from the medium. The timing of the
uncorrelated optical emission is strongly dependent on the nature of the
medium.Comment: 9 pages, 4 figures. Note: This paper has been accepted for
publication in Nature, but is embargoed for discussion in the popular press
until formal publication in Nature. Resubmit - Added table comparing Swift
and RAPTOR dat
Measurement of the Relative Branching Fraction of to Charged and Neutral B-Meson Pairs
We analyze 9.7 x 10^6 B\bar{B}$ pairs recorded with the CLEO detector to
determine the production ratio of charged to neutral B-meson pairs produced at
the Y(4S) resonance. We measure the rates for B^0 -> J/psi K^{(*)0} and B^+ ->
J/psi K^{(*)+} decays and use the world-average B-meson lifetime ratio to
extract the relative widths f+-/f00 = Gamma(Y(4S) -> B+B-)/Gamma(Y(4S) ->
B0\bar{B0}) = = 1.04 +/- 0.07(stat) +/- 0.04(syst). With the assumption that
f+- + f00 = 1, we obtain f00 = 0.49 +/- 0.02(stat) +/- 0.01(syst) and f+- =
0.51 +/- 0.02(stat) +/- 0.01(syst). This production ratio and its uncertainty
apply to all exclusive B-meson branching fractions measured at the Y(4S)
resonance.Comment: 11 pages postscript, also available through
http://w4.lns.cornell.edu/public/CLN
First Observation of the Decays and B^{0}\to D^{*-}p\bar{n}$
We report the first observation of exclusive decays of the type B to D^* N
anti-N X, where N is a nucleon. Using a sample of 9.7 times 10^{6} B-Bbar pairs
collected with the CLEO detector operating at the Cornell Electron Storage
Ring, we measure the branching fractions B(B^0 \to D^{*-} proton antiproton
\pi^+) = ({6.5}^{+1.3}_{-1.2} +- 1.0) \times 10^{-4} and B(B^0 \to D^{*-}
proton antineutron) = ({14.5}^{+3.4}_{-3.0} +- 2.7) times 10^{-4}. Antineutrons
are identified by their annihilation in the CsI electromagnetic calorimeter.Comment: 9 pages postscript, also available through
http://w4.lns.cornell.edu/public/CLN
Study of the Decays B0 --> D(*)+D(*)-
The decays B0 --> D*+D*-, B0 --> D*+D- and B0 --> D+D- are studied in 9.7
million Y(4S) --> BBbar decays accumulated with the CLEO detector. We determine
Br(B0 --> D*+D*-) = (9.9+4.2-3.3+-1.2)e-4 and limit Br(B0 --> D*+D-) < 6.3e-4
and Br(B0 --> D+D-) < 9.4e-4 at 90% confidence level (CL). We also perform the
first angular analysis of the B0 --> D*+D*- decay and determine that the
CP-even fraction of the final state is greater than 0.11 at 90% CL. Future
measurements of the time dependence of these decays may be useful for the
investigation of CP violation in neutral B meson decays.Comment: 21 pages, 5 figures, submitted to Phys. Rev.
A Search for
We report results of a search for in a sample of 9.7 million
charged meson decays. The search uses both and
decay modes of the , and demands exclusive reconstruction of the
companion decay to suppress background. We set an upper limit on the
branching fraction at 90%
confidence level. With slight modification to the analysis we also establish
at 90% confidence
level.Comment: 10 ages postscript, also available through
http://w4.lns.cornell.edu/public/CLN
Measurements of B --> D_s^{(*)+} D^{*(*)} Branching Fractions
This article describes improved measurements by CLEO of the and branching fractions, and first evidence
for the decay , where
represents the sum of the , , and
L=1 charm meson states. Also reported is the first
measurement of the polarization in the decay . A partial reconstruction technique, employing only the fully
reconstructed and slow pion from the decay, enhances sensitivity. The observed branching fractions are
, , and , where the first error is statistical,
the second systematic, and the third is due to the uncertainty in the branching fraction. The measured longitudinal
polarization, , is consistent with
the factorization prediction of 54%.Comment: 26 pages (LaTeX), 15 figures. To be submitted to PR
Improved Measurement of the Pseudoscalar Decay Constant
We present a new determination of the Ds decay constant, f_{Ds} using 5
million continuum charm events obtained with the CLEO II detector. Our value is
derived from our new measured ratio of widths for Ds -> mu nu/Ds -> phi pi of
0.173+/- 0.021 +/- 0.031. Taking the branching ratio for Ds -> phi pi as (3.6
+/- 0.9)% from the PDG, we extract f_{Ds} = (280 +/- 17 +/- 25 +/- 34){MeV}. We
compare this result with various model calculations.Comment: 23 page postscript file, postscript file also available through
http://w4.lns.cornell.edu/public/CLN
Precise Measurement of B^{0}\to \bar{B^{0} Mixing Parameters at the S)$
We describe a measurement of B^0-B^0bar mixing parameters exploiting a method
of partial reconstruction of the decay chains B0 -> D^{*-}\pi^+ and B0 ->
D^{*-}\rho^+. Using 9.6 x 10^6 BBbar pairs collected at the Cornell Electron
Storage Ring, we find \chi_d = 0.198 +- 0.013 +- 0.014, |y_d|<0.41 at 95%
confidence level, and |Re(\epsilon_B)|<0.034 at 95% confidence level.Comment: 11 pages postscript, also available through
http://w4.lns.cornell.edu/public/CLN
First Observation of and Decays
We have observed new channels for decays with an in the final
state. We study 3-prong tau decays, using the and
\eta\to 3\piz decay modes and 1-prong decays with two \piz's using the
channel. The measured branching fractions are
\B(\tau^{-}\to \pi^{-}\pi^{-}\pi^{+}\eta\nu_{\tau})
=(3.4^{+0.6}_{-0.5}\pm0.6)\times10^{-4} and \B(\tau^{-}\to
\pi^{-}2\piz\eta\nu_{\tau}
=(1.4\pm0.6\pm0.3)\times10^{-4}. We observe clear evidence for
substructure and measure \B(\tau^{-}\to
f_1\pi^{-}\nu_{\tau})=(5.8^{+1.4}_{-1.3}\pm1.8)\times10^{-4}. We have also
searched for production and obtain 90% CL upper limits
\B(\tau^{-}\to \pi^{-}\eta'\nu_\tau)<7.4\times10^{-5} and \B(\tau^{-}\to
\pi^{-}\piz\eta'\nu_\tau)<8.0\times10^{-5}.Comment: 11 page postscript file, postscript file also available through
http://w4.lns.cornell.edu/public/CLN
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