Physical Sciences and Mathematics Commons^™

Stellar Metallicity Gradients In Sdss Galaxies, Benjamin Roig, Michael R. Blanton, Renbin Yan

Physics and Astronomy Faculty Publications

We infer stellar metallicity and abundance ratio gradients for a sample of red galaxies in the Sloan Digital Sky Survey (SDSS) Main galaxy sample. Because this sample does not have multiple spectra at various radii in a single galaxy, we measure these gradients statistically. We separate galaxies into stellar mass bins, stack their spectra in redshift bins, and calculate the measured absorption-line indices in projected annuli by differencing spectra in neighboring redshift bins. After determining the line indices, we use stellar population modeling from the EZ_Ages software to calculate ages, metallicities, and abundance ratios within each annulus. Our data cover …

Supermassive Black Hole Formation At High Redshifts Via Direct Collapse In A Cosmological Context, Jun-Hwan Choi, Isaac Shlosman, Mitchell C. Begelman

Physics and Astronomy Faculty Publications

We study the early stage of the formation of seed supermassive black holes via direct collapse in dark matter (DM) haloes, in the cosmological context. We perform high-resolution zoom-in simulations of such collapse at high z. Using the adaptive mesh refinement code enzo, we resolve the formation and growth of a DM halo, until its virial temperature reaches ∼10⁴ K, atomic cooling turns on, and collapse ensues. We demonstrate that direct collapse proceeds in two stages, although they are not well separated. The first stage is triggered by the onset of atomic cooling, and leads to rapidly increasing …

Secondary Organic Aerosol Formation From The Β-Pinene+No3 System: Effect Of Humidity And Peroxy Radical Fate, C. M. Boyd, J. Sanchez, L. Xu, Alexis J. Eugene, T. Nah, W. Y. Tuet, Marcelo I. Guzman, N. L. Ng

Chemistry Faculty Publications

The formation of secondary organic aerosol (SOA) from the oxidation of β-pinene via nitrate radicals is investigated in the Georgia Tech Environmental Chamber (GTEC) facility. Aerosol yields are determined for experiments performed under both dry (relative humidity (RH) < 2 %) and humid (RH = 50 % and RH = 70 %) conditions. To probe the effects of peroxy radical (RO₂) fate on aerosol formation, "RO₂ + NO₃ dominant" and "RO₂ + HO₂ dominant" experiments are performed. Gas-phase organic nitrate species (with molecular weights of 215, 229, 231, and 245 amu, which likely correspond to molecular formulas of C₁₀H₁₇NO₄, C₁₀H₁₅NO₅, C₁₀H₁₇NO …

Stout: Cloudy's Atomic And Molecular Database, Matt L. Lykins, Gary J. Ferland, R. Kisielius, Marios Chatzikos, R. L. Porter, P. A. M. Van Hoof, R. J. R. Williams, F. P. Keenan, P. C. Stancil

Physics and Astronomy Faculty Publications

We describe a new atomic and molecular database we developed for use in the spectral synthesis code Cloudy. The design of Stout is driven by the data needs of Cloudy, which simulates molecular, atomic, and ionized gas with kinetic temperatures 2.8 K < T <10¹⁰ K and densities spanning the low-to high-density limits. The radiation field between photon energies 10⁻⁸ Ry and 100 MeV is considered, along with all atoms and ions of the lightest 30 elements, and ~10² molecules. For ease of maintenance, the data are stored in a format as close as possible to the original data …

Crystal Structure Of Orthorhombic {Bis-[(Pyridin-2-Yl)Methyl](3,5,5,5-Tetrachloropentyl)Amine-Κ3N,N',N''}Chloridocopper(Ii) Perchlorate, Katherine A. Bussey, Annie R. Cavalier, Jennifer R. Connell, Margaret E. Mraz, Kayode D. Oshin, Tomislav Pintauer, Danielle L. Gray, Sean Parkin

Chemistry Faculty Publications

In the title compound, [CuCl(C₁₇H₁₉Cl₄N₃)]ClO₄, the Cu^II ion adopts a distorted square-planar geometry defined by one chloride ligand and the three nitro­gen atoms from the bis­[(pyridin-2-yl)meth­yl](3,5,5,5-tetra­chloro­pent­yl)amine ligand. The perchlorate counter-ion is disordered over three sets of sites with refined occupancies 0.0634 (17), 0.221 (16) and 0.145 (7). In addition, the hetero-scorpionate arm of the bis­[(pyridin-2-yl)meth­yl](3,5,5,5-tetra­chloro­pent­yl)amine ligand is disordered over two sets of sites with refined occupancies 0.839 (2) and 0.161 (2). In the crystal, weak Cu⋯Cl inter­actions between symmetry-related mol­ecules create a dimerization with a chloride occupying the apical …

Soil Quality In Relation To Forest Conversion To Perennial Or Annual Cropping In Southern Brazil, Elcio Liborio Balota, Ines Fumiko Ubukata Yada, Higo Furlan Amaral, Andre Shigueyoshi Nakatani, Mariangela Hungria, Richard Peter Dick, Mark S. Coyne

Plant and Soil Sciences Faculty Publications

Many forested areas have been converted to intensive agricultural use to satisfy food, fiber, and forage production for a growing world population. There is great interest in evaluating forest conversion to cultivated land because this conversion adversely affects several soil properties. We examined soil microbial, physical, and chemical properties in an Oxisol (Latossolo Vermelho distrófico) of southern Brazil 24 years after forest conversion to a perennial crop with coffee or annual grain crops (maize and soybeans) in conventional tillage or no-tillage. One goal was to determine which soil quality parameters seemed most sensitive to change. A second goal …

A Sensitive Faraday Rotation Setup Using Triple Modulation, G. Phelps, Josh Abney, Mark Broering, Wolfgang Korsch

Physics and Astronomy Faculty Publications

The utilization of polarized targets in scattering experiments has become a common practice in many major accelerator laboratories. Noble gases are especially suitable for such applications, since they can be easily hyper-polarized using spin exchange or metastable pumping techniques. Polarized helium-3 is a very popular target because it often serves as an effective polarized neutron due to its simple nuclear structure. A favorite cell material to generate and store polarized helium-3 is GE-180, a relatively dense aluminosilicate glass. In this paper, we present a Faraday rotation method, using a new triple modulation technique, where the measurement of the Verdet constants …

Evolution Of Magnetism In Single-Crystal Ca2Ru1−XIrXO4(0≤X≤0.65), Shujuan Yuan, Jsaminka Terzic, J. C. Wang, L. Li, Saicharan Aswartham, W. H. Song, F. Ye, Gang Cao

Physics and Astronomy Faculty Publications

We report structural, magnetic, transport, and thermal properties of single-crystal Ca₂Ru_1−xIr_xO₄(0≤x≤0.65). Ca₂RuO₄ is a structurally driven Mott insulator with a metal-insulator transition at T_MI=357K, which is well separated from antiferromagnetic order at T_N=110K. Substitution of a 5_d element, Ir, for Ru enhances spin-orbit coupling and locking between the structural distortions and magnetic moment canting. Ir doping intensifies the distortion or rotation of Ru/IrO₆ octahedra and induces weak ferromagnetic behavior along the c axis. In particular, Ir doping suppresses T_N but …

Moments Of The Neutron G2 Structure Function At Intermediate Q2, Wolfgang Korsch, P. Solvignon, N. Liyanage, J.-P. Chen, Seonho Choi, K. Slifer, K. Aniol, T. Averett, W. Boeglin, A. Camsonne, G. D. Cates

Physics and Astronomy Faculty Publications

We present new experimental results for the ³He spin structure function g₂ in the resonance region at Q² values between 1.2 and 3.0(GeV/c)². Spin dependent moments of the neutron were extracted. Our main result, the inelastic contribution to the neutron d₂ matrix element, was found to be small at ⟨Q²⟩=2.4(GeV/c)² and in agreement with the lattice QCD calculation. The Burkhardt-Cottingham sum rule for ³He and the neutron was tested with the measured data and using the Wandzura-Wilczek relation for the low x unmeasured region.

Beam-Energy-Dependent Two-Pion Interferometry And The Freeze-Out Eccentricity Of Pions Measured In Heavy Ion Collisions At The Star Detector, J. Kevin Adkins, Renee Fatemi, Suvarna Ramachandran, G. Webb, L. Adamczyk, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, I. Alekseev, J. Alford, C. D. Anson, A. Aparin

Physics and Astronomy Faculty Publications

We present results of analyses of two-pion interferometry in Au+Au collisions at √^S_NN=7.7, 11.5, 19.6, 27, 39, 62.4, and 200 GeV measured in the STAR detector as part of the BNL Relativistic Heavy Ion Collider Beam Energy Scan program. The extracted correlation lengths (Hanbury-Brown–Twiss radii) are studied as a function of beam energy, azimuthal angle relative to the reaction plane, centrality, and transverse mass (m_T) of the particles. The azimuthal analysis allows extraction of the eccentricity of the entire fireball at kinetic freeze-out. The energy dependence of this observable is expected to be sensitive …

Smooth And Fast Versus Instantaneous Quenches In Quantum Field Theory, Sumit R. Das, Damián A. Galante, Robert C. Myers

Physics and Astronomy Faculty Publications

We examine in detail the relationship between smooth fast quantum quenches, characterized by a time scale δt, and instantaneous quenches, within the framework of exactly solvable mass quenches in free scalar field theory. Our earlier studies [1, 2] highlighted that the two protocols remain distinct in the limit δt → 0 because of the relation of the quench rate to the UV cut-off, i.e., 1/δt ≪ Λ always holds in the fast smooth quenches while 1/δt ∼ Λ for instantaneous quenches. Here we study UV finite quantities like correlators at …

Double Spin Asymmetries Of Inclusive Hadron Electroproduction From A Transversely Polarized 3He Target, C. Dutta, A. Kolarkar, Wolfgang Korsch, Y. X. Zhao, K. Allada, K. Aniol, J. R. M. Annand, T. Averett, F. Benmokhtar, W. Bertozzi, P. C. Bradshaw, P. Bosted, A. Camsonne

Physics and Astronomy Faculty Publications

We report the measurement of beam-target double spin asymmetries (A_LT) in the inclusive production of identified hadrons, e⃗ + ³He^↑→h+X, using a longitudinally polarized 5.9-GeV electron beam and a transversely polarized ³He target. Hadrons (π^±,K^±, and proton) were detected at 16^∘ with an average momentum ⟨P_h⟩=2.35 GeV/c and a transverse momentum (p_T) coverage from 0.60 to 0.68 GeV/c. Asymmetries from the ³He target were observed to be nonzero for π^± production when the target …

Hard Three-Loop Corrections To Hyperfine Splitting In Positronium And Muonium, Michael I. Eides, Valery A. Shelyuto

Physics and Astronomy Faculty Publications

We consider hard three-loop corrections to hyperfine splitting in muonium and positronium generated by the diagrams with closed electron loops. There are six gauge-invariant sets of such diagrams that generate corrections of order mα⁷. The contributions of these diagrams are calculated for an arbitrary electron-muon mass ratio without expansion in the small mass ratio. We obtain the formulas for contributions to hyperfine splitting that in the case of a small mass ratio describe corrections for muonium and in the case of equal masses describe corrections for positronium. The first few terms of the expansion of hard corrections in …

Observing Strategy For The Sdss-Iv/Manga Ifu Galaxy Survey, David R. Law, Renbin Yan, Matthew A. Bershady, Kevin Bundy, Brian Cherinka, Niv Drory, Nicholas Macdonald, José R. Sánchez-Gallego, David R. Wake, Anne-Marie Weijmans, Michael R. Blanton, Mark A. Klaene, Sean M. Moran, Sebastian F. Sanchez, Kai Zhang

Physics and Astronomy Faculty Publications

Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) is an integral-field spectroscopic survey that is one of three core programs in the fourth-generation Sloan Digital Sky Survey (SDSS-IV). MaNGA's 17 pluggable optical fiber-bundle integral field units (IFUs) will observe a sample of 10,000 nearby galaxies distributed throughout the SDSS imaging footprint (focusing particularly on the North Galactic Cap). In each pointing these IFUs are deployed across a 3° field; they yield spectral coverage 3600−10300 Å at a typical resolution R ~ 2000, and sample the sky with 2'' diameter fiber apertures with a total bundle fill factor of 56%. Observing …

All-Weather Surfaces For Cattle Watering Facilities, Stephen F. Higgins, Kylie Schmidt, Donald J. Stamper, Kevin Laurent

Agriculture and Natural Resources Publications

A livestock watering area includes a watering facility and the heavy-use-area (HUA) surrounding it. Without protection, the HUA can develop surface depressions. Surface depressions can render the watering facility inaccessible and no longer frost-proof. Surface depressions also collect rainwater and excrement, creating mud and conditions adverse to livestock health (Figure 1).

Slaframine Toxicosis Or “Slobbers” In Cattle And Horses, Michelle Arnold, S. Ray Smith

Agriculture and Natural Resources Publications

An exceptionally wet summer weather pattern favors the growth of fungi on plants in the field and increases the risk for production of mycotoxins. Mycotoxins are naturally occurring compounds, some of which are toxic to cattle and horses, produced by fungi invading plant material. In the late 1940s and through the 1950s, beef and dairy producers and horse owners reported outbreaks of excessive salivation (slobbering) in cattle and horses associated with the consumption of second-cutting red clover (Trifolium pratense) and occasionally other legumes in the form of hay, pasture, or silage. It was not until the 1960s that …

Acute Or Atypical Interstitial Pneumonia (Aip), Michelle Arnold, Jeff Lehmkuhler

Agriculture and Natural Resources Publications

Acute or atypical interstitial pneumonia (AIP) is terminology used by veterinary pathologists to describe a characteristic pattern of damage in the lungs of cattle. At necropsy, the first indication of AIP-affected lungs is they fill the thorax and do not collapse like normal lungs when the chest cavity is opened. On further investigation, the AIP lungs are found to be semi-firm with a rubbery texture; not hard and consolidated as occurs in bacterial bronchopneumonia. Large air bubbles are found between portions of the lung (see Figure 1, “interlobular” or “bullous” emphysema) and the cut surface of the lung may appear …

Staggers (Tremorgenic Syndrome), Michelle Arnold

Agriculture and Natural Resources Publications

“Staggers” is an all-inclusive term for a group of nervous system disorders caused by indole-diterpenoid mycotoxins produced by various types of fungi on forages. These mycotoxins are collectively known as “tremorgens” (Table 1), and they may be found in several types of grasses at varying stages of maturity. The three main grass types associated with tremorgenic syndrome are Paspalum spp. (dallisgrass and bahiagrass), Cynodon dactylon (bermudagrass) and Lolium perenne (perennial ryegrass). Clinical signs are characterized by tremors and incoordination that tend to worsen with excitement or movement.

Guía De Monitoreo De Mip Para Plagas Comunes De Los Cultivos Cucurbitáceos En Kentucky, Kenneth W. Seebold, Timothy Coolong, Terry Jones, John Strang, Ricardo Bessin, Cheryl A. Kaiser

Agriculture and Natural Resources Publications

Mucho antes de que el término “sostenible” se hiciera tan conocido, los agricultores ya estaban implementando prácticas sostenibles en forma de estrategias de manejo integrado de plagas. El MIP usa una combinación de métodos biológicos, de cultivo, físicos, y químicos que reducen y/o manejan las poblaciones de pestes. Estas estrategias son usadas para minimizar los riesgos ambientales, de costos, y peligros a la salud. Las plagas son manejadas para reducir su impacto negativo en el cultivo, aunque raramente las pestes son eliminadas.

Coexisting Charge And Magnetic Orders In The Dimer-Chain Iridate Ba5Alir2O11, Jsaminka Terzic, J. C. Wang, Feng Ye, W. H. Song, Shujuan Yuan, Saicharan Aswartham, Lance E. De Long, S. V. Streltsov, D. I. Khomskii, Gang Cao

Physics and Astronomy Faculty Publications

We have synthesized and studied single-crystal Ba₅AlIr₂O₁₁ that features dimer chains of two inequivalent octahedra occupied by tetravalent Ir⁴⁺(5d⁵) and pentavalent Ir⁵⁺(5d⁴) ions, respectively. Ba₅AlIr₂O₁₁ is a Mott insulator that undergoes a subtle structural phase transition near T_S=210K and a magnetic transition at T_M=4.5K; the latter transition is surprisingly resistant to applied magnetic fields μ_oH≤12T but more sensitive to modest applied pressure (dT_M/dp≈+0.61K/GPa). All results indicate that the …

Observation Of Charge Asymmetry Dependence Of Pion Elliptic Flow And The Possible Chiral Magnetic Wave In Heavy-Ion Collisions, J. Kevin Adkins, Renee Fatemi, Suvarna Ramachandran, L. Adamczyk, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, I. Alekseev, J. Alford, A. Aparin, D. Arkhipkin, E. C. Aschenauer, G. S. Averichev

Physics and Astronomy Faculty Publications

We present measurements of π⁻ and π⁺ elliptic flow, v₂, at midrapidity in Au+Au collisions at √^S_NN=200, 62.4, 39, 27, 19.6, 11.5, and 7.7 GeV, as a function of event-by-event charge asymmetry, A_ch, based on data from the STAR experiment at RHIC. We find that π⁻ (π⁺) elliptic flow linearly increases (decreases) with charge asymmetry for most centrality bins at √^S_NN=27  GeV and higher. At √^S_NN=200  GeV, the slope of the difference of v₂ between π⁻ and π^{+ …}

Detection Of Small-Scale Rockfall Incidents Using Their Seismic Signature, Achilleas Tripolitsiotis, Antonis Daskalakis, Stelios Mertikas, Dionysios Hristopulos, Zacharias Agioutantis, Panagiotis Partsinevelos

Mining Engineering Faculty Publications

Several algorithms have been effectively used to identify the seismic signature of rockfall incidents, which constitute a significant threat for human lives and infrastructure especially when occurring along transportation networks. These algorithms have been mostly evaluated using data from large scale rockfall events that release a large amount of energy. However, low-energy rockfall events (< 100 Joules) triggered by small-sized individual rocks falling from small heights can be severely destructive. In this study, a three-parameter algorithm has been developed to identify low-energy rockfall events. An experimental setup was implemented to 1) validate the results obtained by this algorithm against visual inspection of seismic signals records, 2) define the optimal algorithm parameterization to minimize false alarms, and 3) investigate whether tri-axial vibration monitoring can be replaced by a uniaxial device in order to reduce the installation cost of a real-time rockfall monitoring system. It was found that the success rate of the proposed algorithm exceeds 80% independently of the parameters used, while event identification at a maximum distance with minimal false alarms was achieved when using mean ± 3σ as the threshold criterion and 6 ms and 4 ms as the trigger and event window parameters respectively. Finally, it was found that for the specific experimental setup, a uniaxial device could be used for rockfall event identification.

First Measurement Of The Atomic Electric Dipole Moment Of 225Ra, R. H. Parker, M. R. Dietrich, M. R. Kalita, N. D. Lemke, K. G. Bailey, M. Bishof, J. P. Greene, R. J. Holt, Wolfgang Korsch, Z.-T. Lu, P. Mueller, T. P. O'Connor, J. T. Singh

Physics and Astronomy Faculty Publications

The radioactive radium-225 (²²⁵Ra) atom is a favorable case to search for a permanent electric dipole moment. Because of its strong nuclear octupole deformation and large atomic mass, ²²⁵Ra is particularly sensitive to interactions in the nuclear medium that violate both time-reversal symmetry and parity. We have developed a cold-atom technique to study the spin precession of ²²⁵Ra atoms held in an optical dipole trap, and demonstrated the principle of this method by completing the first measurement of its atomic electric dipole moment, reaching an upper limit of |d(²²⁵Ra)|<5.0×10⁻²²  e cm …

Star Formation And Quenching Among The Most Massive Galaxies At Z ∼ 1.7, C. Mancini, A. Renzini, E. Daddi, G. Rodighiero, S. Berta, N. Grogin, Dale D. Kocevski, A. Koekemoer

Physics and Astronomy Faculty Publications

We have conducted a detailed object-by-object study of a mass-complete (M_* ≥ 10¹¹ M_⊙) sample of 56 galaxies at 1.4 ≤ z ≤ 2 in the Great Observatories Origins Deep Survey-South field, showing that an accurate deblending in 24 μm images is essential to properly assign to each galaxy its own star formation rate (SFR), whereas an automatic procedure often fails. This applies especially to galaxies with SFRs below the main sequence (MS) value, which may be in their quenching phase. After that, the sample splits evenly between galaxies forming stars within a factor of …

Large-Scale Geo-Facial Image Analysis, Mohammed T. Islam, Connor Greenwell, Richard Souvenir, Nathan Jacobs

Computer Science Faculty Publications

While face analysis from images is a well-studied area, little work has explored the dependence of facial appearance on the geographic location from which the image was captured. To fill this gap, we constructed GeoFaces, a large dataset of geotagged face images, and used it to examine the geo-dependence of facial features and attributes, such as ethnicity, gender, or the presence of facial hair. Our analysis illuminates the relationship between raw facial appearance, facial attributes, and geographic location, both globally and in selected major urban areas. Some of our experiments, and the resulting visualizations, confirm prior expectations, such as the …

Low-Voltage Polymer/Small-Molecule Blend Organic Thin-Film Transistors And Circuits Fabricated Via Spray Deposition, Simon Hunter, Jeremy W. Ward, Marcia M. Payne, John E. Anthony, Oana D. Jurchescu, Thomas D. Anthopoulos

Chemistry Faculty Publications

Organic thin-film electronics have long been considered an enticing candidate in achieving high-throughput manufacturing of low-power ubiquitous electronics. However, to achieve this goal, more work is required to reduce operating voltages and develop suitable mass-manufacture techniques. Here, we demonstrate low-voltage spray-cast organic thin-film transistors based on a semiconductor blend of 2,8-difluoro- 5,11-bis (triethylsilylethynyl) anthradithiophene and poly(triarylamine). Both semiconductor and dielectric films are deposited via successive spray deposition in ambient conditions (air with 40%–60% relative humidity) without any special precautions. Despite the simplicity of the deposition method, p-channel transistors with hole mobilities of >1 cm²/Vs are realized at −4 …

The Strain Seismograms Of P- And S-Waves Of A Local Event Recorded By Four-Gauge Borehole Strainmeter, Zehua Qui, Shunliang Chi, Zhenming Wang, Seth Carpenter, Lei Tang, Yanping Guo, Guang Yang

Faculty, Staff, and Affiliated Publications--KGS

At a sampling rate of 100 samples per second, the YRY-4 four-gauge borehole strainmeters (FGBS) are capable of recording transient strains caused by seismic waves such as P and S waves or strain seismograms. At such a high sampling rate, data from the YRY-4 strainmeters demonstrate fairly satisfactory self-consistency. The strain tensor seismograms demonstrate the senses of motion of P waves, that is, the type of seismic wave travels in the direction of the maximum normal strain change. The observed strain patterns of S waves significantly differ from those of P waves and should contain information about the source mechanism. …

Variability Of The Coronal Line Region In Ngc 4151, Hermine Landt, Martin J. Ward, Katrien C. Steenbrugge, Gary J. Ferland

Physics and Astronomy Faculty Publications

We present the first extensive study of the coronal line variability in an active galaxy. Our data set for the nearby source NGC 4151 consists of six epochs of quasi-simultaneous optical and near-infrared spectroscopy spanning a period of about 8 yr and five epochs of X-ray spectroscopy overlapping in time with it. None of the coronal lines showed the variability behaviour observed for the broad emission lines and hot dust emission. In general, the coronal lines varied only weakly, if at all. Using the optical [Fe vii] and X-ray O vii emission lines we estimate that the coronal line gas …

Faint Agns At Z > 4 In The Candels Goods-S Field: Looking For Contributors To The Reionization Of The Universe, E. Giallongo, A. Grazian, F. Fiore, A. Fontana, L. Pentericci, E. Vanzella, M. Dickinson, Dale D. Kocevski, M. Castellano, S. Christiani, H. Ferguson, S. Finkelstein, N. Grogin, N. Hathi, A. M. Koekemoer, J. A. Newman, M. Salvato

Physics and Astronomy Faculty Publications

Context. Establishing the number of faint active galactic nuclei (AGNs) at z = 4−6 is crucial to understanding their cosmological importance as main contributors to the reionization of the Universe.

Aims. In order to derive the AGN contribution to the cosmological ionizing emissivity we have selected faint AGN candidates at z> 4 in the CANDELS GOODS-South field, which is one of the deepest fields with extensive multiwavelength coverage from Chandra, HST, Spitzer, and various ground-based telescopes.

Methods. We have adopted a relatively novel criterion. As a first step, high redshift galaxies are selected in the NIR H band …

Estimated Probability Of Becoming A Case Of Drug Dependence In Relation To Duration Of Drug-Taking Experience: A Function Approach, Olga A. Vsevolozhskaya, James C. Anthony

Olga A. Vsevolozhskaya

Measured as elapsed time from first use to dependence syndrome onset, the estimated 'induction interval' for cocaine clearly is short relative to the cannabis interval, but little is known about risk of becoming dependent when use persists. Published estimates for this facet of drug dependence epidemiology are from life histories elicited years after first use. To improve estimation, we turn to new data from nationally representative samples of newly incident drug users identified via probability sampling and confidential computer-assisted self-interviews for the National Surveys on Drug Use and Health, 2004-2013. Standardized modules assess first and most recent use, and dependence …