5,102 research outputs found
Raman spectroscopy of iodine-doped double-walled carbon nanotubes
We present a Raman spectroscopy study of iodine-intercalated (p-type-doped)
double-walled carbon nanotubes. Double-walled carbon nanotubes (DWCNTs) are
synthesized by catalytic chemical vapor deposition and characterized by Raman
spectroscopy. The assignment of the radial breathing modes and the tangential
modes of pristine DWCNTs is done in the framework of the bond polarization
theory, using the spectral moment method. The changes in the Raman spectrum
upon iodine doping are analyzed. Poly-iodine anions are identi- fied, and the
Raman spectra reveal that the charge transfer between iodine and DWCNTs only
involves the outer tubes
Parsec-scale structures and diffuse bands in a translucent interstellar medium at z 0.079
We present a detailed study of the QSO-galaxy pair [SDSS J163956.35+112758.7
(zq = 0.993) and SDSS J163956.38+112802.1 (zg = 0.079)] based on observations
carried out using the Giant Meterwave Radio Telescope (GMRT), the Very Large
Baseline Array (VLBA), the Sloan Digital Sky Survey (SDSS) and the ESO New
Technology Telescope (NTT). We show that the interstellar medium of the galaxy
probed by the QSO line of sight has near-solar metallicity (12+log(O/H) =
8.47+/-0.25) and dust extinction (E(B-V) 0.83+/-0.11) typical of what is
usually seen in translucent clouds. We report the detection of absorption in
the \lambda 6284 diffuse interstellar band (DIB) with a rest equivalent width
of 1.45+/-0.20\AA. Our GMRT spectrum shows a strong 21-cm absorption at the
redshift of the galaxy with an integrated optical depth of 15.70+/-0.13 km/s.
Follow-up VLBA observations show that the background radio source is resolved
into three components with a maximum projected separation of 89 pc at the
redshift of the galaxy. One of these components is too weak to provide useful
HI 21-cm absorption information. The integrated HI optical depth towards the
other two components are higher than that measured in our GMRT spectrum and
differ by a factor 2. By comparing the GMRT and VLBA spectra we show the
presence of structures in the 21-cm optical depth on parsec scales. We discuss
the implications of such structures for the spin-temperature measurements in
high-z damped Lyman-alpha systems. The analysis presented here suggests that
this QSO-galaxy pair is an ideal target for studying the DIBs and molecular
species using future observations in optical and radio wavebands.Comment: 10 pages, 8 figures, 2 tables, accepted for publication in MNRA
Ark or park: the need to predict relative effectiveness of ex situ and in situ conservation before attempting captive breeding
1. When species face extinction, captive breeding may be appropriate. However, captive breeding may be unsuccessful, while reducing motivation and resources for in situ conservation and impacting wild source populations. Despite such risks, decisions are generally taken without rigorous evaluation. We develop an individual-based, stochastic population model to evaluate the potential effectiveness of captive-breeding and release programmes, illustrated by the Critically Endangered Ardeotis nigriceps Vigors great Indian bustard. 2. The model was parameterized from a comprehensive review of captive breeding and wild demography of large bustards. To handle uncertainty in the standards of captive-breeding performance that may be achieved we explored four scenarios of programme quality: ‘full-range’ (parameters sampled across the observed range), ‘below-average’, ‘above-average’ and ‘best possible’ (performance observed in exemplary breeding programmes). Results are evaluated examining i) the probability of captive population extirpation within 50 years and ii) numbers of adult females subsequently established in the wild following release, compared to an alternative strategy of in situ conservation without attempting captive breeding. 3. Successful implementation of captive breeding, involving permanent retention of 20 breeding females and release of surplus juveniles, required collection of many wild eggs and consistent ‘best possible’ performance across all aspects of the programme. Under ‘full-range’ and ‘above-average’ scenarios captive population extirpation probabilities were 73–88% % and 23‒51%% respectively, depending on egg collection rates. 4. Although most (73‒92%) ‘best possible’ programmes supported releases, re-establishment of free-living adults also required effective in situ conservation. Incremental implementation of effective conservation measures over the initial 10 years resulted in more free-living adults within 35 years if eggs were left in the wild without attempting captive breeding. 5. Synthesis and applications. For the great Indian bustard Ardeotis nigriceps, rapid implementation of in situ conservation offers a better chance to avoid extinction than captive breeding. Demographic modelling should be used to examine whether captive breeding is likely to bring net benefits to conservation programmes
Thermally isolated Luttinger liquids with noisy Hamiltonians
We study the dynamics of a quantum-coherent thermally isolated Luttinger
liquid with noisy Luttinger parameter. To characterize the fluctuations of the
absorbed energy in generic noise-driven systems, we first identify two types of
energy moments, which can help tease apart the effects of classical
(sample-to-sample) and quantum sources of fluctuations. One type of moment
captures the total fluctuations due to both sources, while the other one
captures the effect of the classical source only. We then demonstrate that in
the Luttinger liquid case, the two types of moments agree in the thermodynamic
limit, indicating that the classical source dominates. In contrast to
equilibrium thermodynamics, in this driven system the relative fluctuations of
energy do not decay with the system size. Additionally, we study the deviations
of equal-time correlation functions from their ground-state value, and find a
simple scaling behavior.Comment: 11 pages, 2 figure
Widely tuneable scattering-type scanning near-field optical microscopy using pulsed quantum cascade lasers
Hubungan Indikator Obesitas dengan Kepadatan Tulang pada Wanita Dewasa Awal
Latar Belakang : Prevalensi osteoporosis pada wanita dewasa di Indonesia tergolong tinggi (32,3%). Osteoporosis dinyatakan berhubungan dengan obesitas. Penilaian status obesitas ditentukan oleh beberapa indikator diantaranya Indeks Massa Tubuh (IMT), persen lemak tubuh dan lingkar pinggang. Beberapa indikator tersebut dinyatakan berpengaruh dengan kepadatan tulang, namun masih dalam perdebatan. Tujuan dari penelitian ini yaitu untuk melihat hubungan antara indikator-indikator obesitas dengan kepadatan tulang pada wanita dewasa awal.Metode : Penelitian ini merupakan penelitian observasional dengan desain penelitian cross-sectional. Subjek 52 orang wanita dewasa awal usia 20-24 tahun dipilih dengan teknik random sampling. Data yang diambil adalah berat badan, persen lemak tubuh, tinggi badan, asupan kalsium, tingkat aktivitas fisik, dan kepadatan tulang. Analisis bivariat dengan uji rank Spearman dan Pearson, sedangkan analisis multivariat menggunakan uji regresi linier ganda.Hasil : Terdapat 23,1 subjek termasuk dalam katergori osteopenia, sedangkan 76,9% subjek lainnya termasuk dalam kategori normal. Indeks Massa Tubuh (IMT), persen lemak tubuh, lingkar pinggang dan aktifitas fisik tidak memiliki hubungan dengan kepadatan tulang. Asupan kalsium sebagai variabel perancu mimiliki hubungan yang bermakna dengan kepadatan tulang (p<0,05).Kesimpulan : Tidak ada hubungan antara IMT, massa lemak tubuh dan lingkar pinggang dengan kepadatan tulang pada wanita dewasa awal
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