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The Golden-cheeked Warbler Dendroica chrysoparia is a federally endangered Neotropical migrant that inhabits montane pine-oak forests in Mexico and northern Central America during the non-breeding season. Although it is known that Golden-cheeked Warblers are closely associated with ‘encino’ oaks (evergreen or holm oak) such as Quercus sapotifolia, Q. eliptica and Q. elongata, which have shiny, narrow, elliptical, or oblong leaves, quantitative habitat targets are useful for effectively incorporating this information into conservation planning and forest management practices. We analysed data on wintering Golden-cheeked Warblers collected during the non-breeding season in Honduras from 1996 to 1998 to identify quantitative targets for habitat conditions for this species. Data on warbler abundance were collected using line transect surveys located in montane pine-oak forests in a stratified-random fashion. Habitat data were collected at five 0.04 ha plots on these same transects and the averaged values used as predictors of Golden-cheeked Warbler abundance. We found that Golden-cheeked Warblers were strongly associated with the basal area of encino oaks and density of ‘roble’ oaks, such as Q. segoviensis, Q. purulhana and Q. rugosa, which have large, lobed leaves. Density of Golden-cheeked Warblers peaked at ≈ 5.6 m2 ha–1 basal area of encino and ≈7 roble oaks ha–1. These values can be used to identify quantitative habitat targets that can be directly incorporated into forest management practices to ensure that these activities maintain habitat conditions necessary for their use by Golden-cheeked Warblers.
Reference dielectric function spectra,ε-ε1+ iε2, for strained Si1-x Gex have been generated for 0<x<0.255. Used in an interpolation procedure they allow multilayer analysis of pseudo-dielectric function spectra, <ε <ε1 + i<ε2, measured by spectroscopic ellipsometry (SE) on strained Si1-xGex/Si structures of arbitrary composition, x≤0.255. These include multi-quantum well (MQW) structures important for application as infrared detectors.
We describe an ongoing, large-scale, photometric and spectroscopic survey of the Large Magellanic Cloud (LMC) periphery. This survey uses Washington M, T2 + DDO51 photometry to identify distant LMC red giant branch (RGB) star candidates; multi-object spectroscopy is used to confirm the stellar surface gravities of these RGB stars and their association with the LMC (e.g., through radial velocities). The survey now encompasses hundreds of fields ranging from the LMC center with full azimuthal coverage around the LMC and out to 23° from the LMC center. We have confirmed the existence of RGB stars with (the unusual) Magellanic velocities out to the radial limit of this survey coverage. From data in a subsample of these fields, we show that this extended population of stars makes up a diffuse structure enveloping the LMC with a two-dimensional distribution resembling a classical halo with a shallow de Vaucouleurs profile and a broad metallicity spread around a typical mean value of [Fe/H] ~ −1.0.
Specialized conduction tissues mediate coordinated propagation of
electrical activity through the adult vertebrate heart. Following
activation of the atria, the activation wave is slowed down in the
atrioventricular canal or node, after which it spreads rapidly into the
left and right ventricles via the His-Purkinje system (HPS). This
results in the ventricles being activated from the apex toward the
base, which is a hallmark of HPS function. The development of mature
HPS function follows significant phases of cardiac morphogenesis.
Initially, the cardiac impulse propagates in a slow, linear, and
isotropic fashion from the sinus venosus at the most caudal portion of
the tubular heart. Although the speed of impulse propagation gradually
increases as it travels toward the anterior regions of the heart tube,
the actual sequence of ventricular activation in the looped heart
proceeds in the same direction as blood flow. Eventually, the immature
base-to-apex sequence of ventricular activation undergoes an apparent
reversal, changing to the mature apex-to-base pattern. Using an optical
mapping approach, we demonstrate that the timing of this last
transition shows striking dependence on hemodynamic loading of the
ventricle, being accelerated by pressure overload and delayed in left
ventricular hypoplasia. Comparison of chick and mammalian hearts
revealed some striking similarities as well as key differences in the
timing of such events during cardiac organogenesis.
To investigate the prevalence and incidence of overweight and obesity, the frequency of overweight resolution and the influence of parental adiposity during middle childhood.
As part of a prospective cohort study, height and weight were measured in 1997 and 2000/2001. Children were classified as non-overweight, overweight or obese based on standard international definitions. Body mass index (BMI) was transformed into age- and gender-specific Z-scores employing the LMS method and 2000 growth chart data of the Centers for Disease Control and Prevention. Parents self-reported height and weight, and were classified as underweight, healthy weight, overweight or obese based on World Health Organization definitions.
Primary schools in Victoria, Australia.
In total, 1438 children aged 5–10 years at baseline.
The prevalence of overweight and obesity increased between baseline (15.0 and 4.3%, respectively) and follow-up (19.7 and 4.8%, respectively; P < 0.001 for increase in overweight and obesity combined). There were 140 incident cases of overweight (9.7% of the cohort) and 24 of obesity (1.7% of the cohort); only 3.8% of the cohort (19.8% of overweight/obese children) resolved to a healthy weight. The stability of child adiposity as measured by BMI category (84.8% remained in the same category) and BMI Z-score (r = 0.84; mean change = −0.05) was extremely high. Mean change in BMI Z-score decreased with age (linear trend β = 0.03, 95% confidence interval 0.01–0.05). The influence of parental adiposity largely disappeared when children's baseline BMI was adjusted for.
During middle childhood, the incidence of overweight/obesity exceeds the proportion of children resolving to non-overweight. However, for most children adiposity remains stable, and stability appears to increase with age. Prevention strategies targeting children in early childhood are required.