Injection Episodes Research Articles

Uso de gabapentina no tratamento da Síndrome SUNCT

We report the cases of two women who presented a clinical condition compatible with the SUNCT (short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing) syndrome. Both presented normal clinical and neurological examination and MRI compatible with microangiopathy. The first one related headache attacks for three years, occurring several times a day when she masticated or yawned. She had a history of multiple failed therapies. The pain was controlled after the use of gabapetin (600 mg per day). The second one related she had daily headaches for six months that occurred from 20 to 40 times per day. At the first visit to the ambulatory, she related she was using carbamazepine (600 mg per day) and chlorpromazine (15 mg per day) having a partial response. Administration of gabapentin (1200 mg per day) led to complete resolution of the pain attacks, but the patient continue to have episodes of conjunctival injection.

A Spectacular Radio Flare from XRF 050416a at 40 Days and Implications for the Nature of X‐Ray Flashes

We present detailed optical, near-infrared, and radio observations of the X-ray flash 050416a obtained with Palomar and Siding Springs Observatories as well as HST and the VLA, placing this event among the best-studied X-ray flashes to date. In addition, we present an optical spectrum from Keck LRIS from which we measure the redshift of the burst, z=0.6528. At this redshift the isotropic-equivalent prompt energy release was about 10^51 erg, and using a standard afterglow synchrotron model we find that the blastwave kinetic energy is a factor of 10 larger, E_K,iso ~ 10^52 erg. The lack of an observed jet break to t ~ 20 days indicates that the opening angle is larger than 7 deg and the total beaming-corrected relativistic energy is larger than 10^50 erg. We further show that the burst produced a strong radio flare at t ~ 40 days accompanied by an observed flattening in the X-ray band which we attribute to an abrupt circumburst density jump or an episode of energy injection (either from a refreshed shock or off-axis ejecta). Late-time observations with HST show evidence for an associated supernova with peak optical luminosity roughly comparable to that of SN 1998bw. Next, we show that the host galaxy of XRF 050416a is actively forming stars at a rate of at least 2 M_solar per year with a luminosity of L_B ~ 0.5L* and metallicity of Z ~ 0.2-0.8 Z_solar. Finally, we discuss the nature of XRF 050416a in the context of short-hard gamma-ray bursts and under the framework of off-axis and dirty fireball models for X-ray flashes.

Gender differences in injection risk behaviors at the first injection episode

Objectives To examine gender differences in drug injection equipment sharing at injecting initiation. Methods Young injecting drug users (IDUs) in New York City February 1999–2003 were surveyed about injection risk behaviors and circumstances at initiation. Analyses were gender-stratified and excluded participants who initiated alone. Multiple logistic regression estimated adjusted odds ratios. Results Participants ( n = 249) were 66% male and 82% White. Mean initiation age was 19.2; mean years since initiating was 3.0. Women were significantly more likely to cite social network influence as a reason for initiating, to have male and sex partner initiators, and to share injecting equipment than men. Among women, sharing any injection equipment was associated with initiation by a sex partner and having ≥2 people present. Among men, being injected by someone else predicted sharing any injection equipment, while using a legally obtained syringe was protective. Conclusions Social persuasion stemming from sexual and/or social relationships with IDUs may increase women's risk of sharing injection equipment at initiation, and consequently, their early parenteral risk of acquiring blood-borne infections. Interventions should focus on likely initiates, especially women in injecting-discordant sex partnerships, and IDUs (potential initiators).

The circumburst environment of a FRED GRB: study of the prompt emission and X-ray/optical afterglow of GRB 051111

Aims. We report a multi-wavelength analysis of the prompt emission and early afterglow of GRB 051111 and discuss its properties in the context of current fireball models. Methods. The detection of GRB 051111 by the Burst Alert Telescope on-board Swift triggered early BVRi’ observations with the 2-m robotic Faulkes Telescope North in Hawaii, as well as X-ray observations with the Swift X-Ray Telescope. Results. The promptγ-ray emission shows a classical FRED profile. The optical aft erglow light curves are fitted with a broken power law, withα1 = 0.35 toα2 = 1.35 and a break time around 12 minutes after the GRB. Although contemporaneous X-ray observations were not taken, a power law connection between theγ-ray tail of the FRED temporal profile and the late XRT flux deca y is feasible. Alternatively, if the X-ray afterglow tracks the optical de cay, this would represent one of the first GRBs for which the ca nonical steep-shallow-normal decay typical of early X-ray afterglows has been monitored optically. We present a detailed analysis of the intrinsic extinction, elemental abundances and spectral e nergy distribution. From the absorption measured in the low X-ray band we find possible evidence for an overabundance of some α elements such as oxygen, [O/Zn]=0.7± 0.3, or, alternatively, for a significant presence of molecular gas. The IR-to-X-ray Spectral Energy Distribution measured at 80 minutes after the burst is consistent with the cooling break lying between the optical and X-ray bands. Extensive modelling of the intrinsic extinction suggests dust with big grains or grey extinction profiles. The early optical break is due ei ther to an energy injection episode or, less probably, to a st ratified wind environment for the circumburst medium.

The Afterglow, Energetics, and Host Galaxy of the Short‐Hard Gamma‐Ray Burst 051221a

We present detailed optical, X-ray, and radio observations of the bright afterglow of the short gamma-ray burst 051221a obtained with Gemini, Swift XRT, and the Very Large Array, as well as optical spectra from which we measure the redshift of the burst, z = 0.5464. At this redshift the isotropic-equivalent prompt energy release was about 1.5 × 1051 ergs, and using a standard afterglow synchrotron model, we find that the blast wave kinetic energy is similar, EK,iso ≈ 8.4 × 1051 ergs. An observed jet break at t ≈ 5 days indicates that the opening angle is θj ≈ 7° and the total beaming-corrected energy is therefore ≈2.5 × 1049 ergs, comparable to the values inferred for previous short GRBs. We further show that the burst experienced an episode of energy injection by a factor of 3.4 between t = 1.4 and 3.4 hr, which was accompanied by reverse shock emission in the radio band. This result provides continued evidence that the central engines of short GRBs may be active significantly longer than the duration of the burst and/or produce a wide range of Lorentz factors. Finally, we show that the host galaxy is actively forming stars at a rate of about 1.6 M☉ yr-1, yet exhibits evidence for an appreciable population of old stars (~1 Gyr) and near-solar metallicity. These properties are intermediate between those of long GRB hosts and previous short burst hosts. The lack of bright supernova emission and the low circumburst density (n ~ 10-3 cm-3), however, continue to support the idea that short bursts are not related to massive stellar death. Given that the total energy release is larger than the predicted yield for a neutrino annihilation mechanism, this suggests that magnetohydrodynamic processes may be required to power the burst.

GRB 051028: an intrinsically faint gamma-ray burst at high redshift?

We present multiwavelength observations of the gamma-ray burst GRB 051028 detected by HETE-2 in order to derive its afterglow emission parameters and to determine the reason for its optical faintness when compared to other events. Observations were taken in the optical (2.0m Himalayan Chandra Telescope, 1.34m Tautenburg, 4.2m William Herschel Telescope) and in X-rays (Swift/XRT) between 2.7 hours and 10 days after the onset of the event. The data can be interpreted by collimated emission in a jet with a typical value of $p$ = 2.4 which is moving in an homogeneous interstellar medium and with a cooling frequency nu_{c} still above the X-rays at 0.5 days after the burst onset. GRB 051028 can be classified as a ``gray'' or ``potentially dark'' GRB. On the basis of the combined optical and Swift/XRT data, we conclude that the reason for the optical dimness is not extra absorption in the host galaxy, but rather the GRB taking place at high-redshift.We also notice the very striking similarity with the optical lightcurve of GRB 050730, a burst with a spectroscopic redshift of 3.967, although GRB 051028 is about 3 mag fainter. We suggest that the bump could be explained by multiple energy injection episodes and that the burst is intrinsically faint when compared to the average afterglows detected since 1997. The non-detection of the host galaxy down to R = 25.1 is also consistent with the burst arising at high redshift, compatible with the published pseudo-z of 3.7 +/- 1.8.

Syringe Disposal Among Injection Drug Users in Harlem and the Bronx During the New York State Expanded Syringe Access Demonstration Program

Effective January 1, 2001, New York State enacted the Expanded Syringe Access Demonstration Program (ESAP), allowing syringes to be sold in pharmacies without a prescription or dispensed through doctors, hospitals, and clinics to adults. A concern in the assessment of ESAP is its effects on syringe disposal practices. Syringe use data regarding the last injection episode were combined from three projects (N = 1,030) recruiting injection drug users. Disposal of syringes by methods known to be safe decreased significantly over time after the implementation of ESAP. Syringes obtained either from syringe exchange programs or ESAP sources were more likely to be disposed of safely than syringes obtained from other sources. Efforts to enlist pharmacists and others involved in ESAP implementation to encourage safe disposal are needed. More detailed information on disposal practices is needed to capture the continuum from least to most safe practices and variation within individuals.

Analysis of the X-ray emission of nine Swift afterglows

The X-ray light-curves of 9 Swift XRT afterglows (050126, 050128, 050219A, 050315, 050318, 050319, 050401, 050408, 050505) display a complex behaviour: a steep t^{-3.0 \pm 0.3} decay until ~400 s, followed by a significantly slower t^{-0.65+/-0.20} fall-off, which at 0.2--2 d after the burst evolves into a t^{-1.7+/-0.5} decay. We consider three possible models for the geometry of relativistic blast-waves (spherical outflows, non-spreading jets, and spreading jets), two possible dynamical regimes for the forward shock (adiabatic and fully radiative), and we take into account a possible angular structure of the outflow and delayed energy injection in the blast-wave, to identify the models which reconcile the X-ray light-curve decay with the slope of the X-ray continuum for each of the above three afterglow phases. By piecing together the various models for each phase in a way that makes physical sense, we identify possible models for the entire X-ray afterglow. The major conclusion of this work is that a long-lived episode of energy injection in the blast-wave, during which the shock energy increases at t^{1.0+/-0.5}, is required for five afterglows and could be at work in the other four as well. Optical observations in conjunction with the X-ray can distinguish among these various models. Our simple tests allow the determination of the location of the cooling frequency relative to the X-ray domain and, thus, of the index of the electron power-law distribution with energy in the blast-wave. The resulting indices are clearly inconsistent with an universal value.

Determinants of Health-Related Quality of Life of Opiate Users at Entry to Low-Threshold Methadone Programs

Objective: The aim of this study was to conduct an exploratory analysis of factors associated with poor health-related quality of life (HRQOL) among opiate users at entry to low-threshold methadone treatment. Methods: The SF-36 questionnaire was administered to 145 opiate users at enrollment into low-threshold methadone maintenance programs. ANOVA and correlational analyses were performed to investigate the determinants of poor physical and mental composite summary scales (PCS and MCS) of the SF-36 among opiate users. Stepwise regression methods were also employed to fit PCS and MCS multivariate models. Results: Age, employment status, chronic medical conditions, hospitalization, emotional abuse, sexual abuse and age at first injection episode were significantly associated with PCS. Mental health problems, sexual abuse, physical abuse, the use of sedatives, the use of cocaine, the number of days of cocaine use, sedative use and multiple substance use in the past month were significantly associated with MCS. The variances in the MCS and PCS were not readily explained by any one factor. Conclusion: The multiplicity of factors influencing HRQOL of opiate users suggests the need for a range of services within the context of a methadone program, addressing primary medical care needs as well as treatment for both mental health problems and abuse issues.

The Effectiveness of Sodium Tetradecyl Sulfate in the Treatment of Wrist Ganglia

Ganglia are the most common benign soft tissue tumours of the hand. Although benign, a significant number of patients with wrist ganglia consult with their general practitioners, and ultimately the hand surgeon, complaining of pain. A great number of patients are concerned about the cosmetic appearance, and an equally significant number genuinely believe that the ganglion is a cancer. There are several management options resulting in varying degrees of success. These include observation only, surgical excision, aspiration only, aspiration with injection of methylprednisolone, and aspiration with injection of methylprednisolone and hyaluronidase. The main objective was to investigate the effectiveness and safety of sodium tetradecyl sulfate as a sclerosing agent after aspiration of wrist ganglia. Initial data were collected prospectively during a period of 48 months. Following this, patients were sent a postal survey at least two years after they had received treatment to access the levels of recurrence and persistent complications. In the short term, 90% of the patients achieved complete resolution after one episode of aspiration and injection. However, there was only a 65% cure rate after two to five years. Complications were few and not significant. Sodium tetradecyl sulfate is an effective sclerosing agent after aspiration of wrist ganglia with an excellent short-term efficacy and a long-term cure rate comparable to that of surgical excision.

HIV Prevalence and Correlates of Receptive Needle Sharing Among Injection Drug Users in the Mexican-U.S. Border City of Tijuana

Injection drug use is a growing but understudied problem in Tijuana, a city situated on the northwestern Mexico-U.S border. The authors studied factors associated with receptive needle sharing in an effort to inform prevention activities. In 2003, street-recruited injection drug users (IDUs) in Tijuana underwent interviews on injection risk behaviors and rapid HIV antibody tests. Logistic regression was used to identify correlates of receptive needle sharing at the last injection episode. Of 402 IDUs, 87.6% were male; the median age was 34. HIV prevalence was 4.01% (95%CI: 2.29–6.51). One third reported receptive needle sharing at last injection. Factors independently associated with receptive needle sharing were years living in Tijuana (Adjusted Odds Ratio [AdjOR]= 0.97 per year, 95% CI: 0.96–0.99), being bisexual/homosexual (AdjOR=2.12; 95% CI: 1.30 – 3.44), unemployed (AdjOR=2.5; 95% CI: 1.52–4.10), never having an HIV test (AOR: 4.02; 95% CI: 2.44–6.60), having friends who placed importance on avoiding HIV (AdjOR: 0.36; 95% CI: 0.19–0.68) and last injecting in a shooting gallery (AdjOR=l.98; 95% CI: 1.21–3.24). These results underscore the need to increase access to voluntary HIV testing and counseling to IDUs and migrants in Tijuana, as well as expand access to sterile syringes in an effort to avert widespread HIV transmission.

Receptive Syringe Sharing Among Injection Drug Users in Harlem and the Bronx During the New York State Expanded Syringe Access Demonstration Program

Effective on January 1, 2001, New York State enacted the Expanded Syringe Access Demonstration Program (ESAP), which allows syringes to be sold in pharmacies without a prescription or dispensed through doctors, hospitals, and clinics to persons 18 years of age or older and permits the possession of those syringes for the purposes of injecting drugs. To assess changes in receptive syringe sharing since the inception of the ESAP. Sociodemographic characteristics and syringe use data regarding the last injection episode were combined from 3 projects (n = 1181) recruiting injection drug users in ongoing studies in Harlem and the Bronx in New York City from January 2001 through June 2003. These data were analyzed as serial cross sections by calendar quarter. Receptive sharing decreased significantly over time, from 13.4% in the first quarter to 3.6% in the last quarter. Obtaining the last injection syringe from an ESAP source (mostly pharmacies) increased significantly over time, from 7.5% in the first quarter to 25.0% in the last quarter. In multiple logistic regression analysis, variables that were significantly associated with less receptive sharing were syringe exchange and ESAP syringe source as well as time since ESAP inception. Female gender and white race/ethnicity were significantly associated with greater receptive sharing. The increase in the use of pharmacies and other ESAP syringe sources in this sample has been accompanied by a decline in receptive sharing.

Drug Sharing Among Heroin Networks: Implications for HIV and Hepatitis B and C Prevention

Qualitative and quantitative findings from the baseline survey of a longitudinal, socially-focused blood-borne disease intervention study among 611 heroin IDU in Denver indicate that high risk injection practices-the sharing of contaminated drug solution in particular-often occur as a consequence of how heroin is obtained, the quantity obtained and the setting where it is injected. Contamination occurs if a contaminated syringe is used to liquefy and apportion the shared drug. In our cohort of 304 heroin injecting networks there was at least one member who, when asked to describe their last injection, reported dividing the drug as a liquid (82%), using a reservoir of water that syringes had been rinsed in to mix drugs (67%), using a common cooker (86%)-a proxy for drug sharing-and beating a shared cotton filter (58%). In contrast, only 22% reported syringe sharing. Variables associated with various injection practices included location of the last injection episode, quantity of drug injected, dope sickness, and years injecting. When compared to those who injected in a safe setting, those in an unsafe location had almost three times the odds (OR = 2.9; 95% CI: 1.9, 4.6) of being part of an injection episode where there was cooker sharing; and the smaller the quantity of heroin (< or =1/4 gram v. > 1/4 gram) present at the episode, the greater the odds that cooker sharing occurred (OR = 1.8; 95% CI: 1.2, 2.6). Use of a used, unbleached syringe to prepare shared drugs had twice the odds of occurring in "unsafe" v. safe settings (OR = 2.2; 95% CI: 1.3, 4.0) and in episodes in which a participant was dopesick (OR = 2.1; 95% CI: 1.2, 3.6). In summary, risky injection practices occur within an injection process that is, in part, a response to a structurally imposed risk environment. Lessening the blood-borne disease risks embedded within this process requires interventions designed to mitigate the environmental factors that influence it, including syringe accessibility, law enforcement strategies and the settings where IDU inject drugs.

Dike intrusions beneath grabens south of Arsia Mons, Mars

The existence of igneous dikes beneath grabens in Tharsis remains contentious due to conflicting observations of Martian geomorphology. We examine the topographic signatures of a Tharsis‐radial graben array in 3 zones south of Arsia Mons. We identify dikes beneath grabens in all of the zones, with fewer dike‐induced grabens closer to Arsia Mons. We infer that a single radial swarm of dikes outside the magmatic source area, central Tharsis, is unlikely. Our observations instead favor a long and varied magmatic history throughout Tharsis with several episodes of dike injection.

Energy Injection Episodes in Gamma-Ray Bursts: The Light Curves and Polarization Properties of GRB 021004

Several GRB afterglow light curves deviate strongly from the power-law decay observed in most bursts. We show that these variations can be accounted for by including refreshed shocks in the standard fireball model previously used to interpret the overall afterglow behavior. As an example, we consider GRB 021004, which exhibited strong light-curve variations and has a reasonably well time-resolved polarimetry. We show that the light curves in the R band, X-rays, and radio can be accounted for by four energy injection episodes in addition to the initial event. The polarization variations are shown to be a consequence of the injections.

Evidence for the prolonged existence of &gt;100 MeV solar protons in coronal structures

Solar proton events (SPEs) of 1989–1992 accompanied by ground-level enhancements of the cosmic-ray intensity are analyzed. A diffusive-propagation model can well approximate the solar proton intensity at energies of 84–200 MeV measured on board the GOES-7 satellite during the first 15–20 hours of the development of an SPE, assuming several episodes of proton injection into interplanetary space over some hours. The detection of π0-decay gamma-ray emission during the flares of June 11 and 15, 1991 on board the CGRO and GAMMA-1 space observatories is the sole experimental evidence for the existence of protons with energies >100 MeV near the Sun over such extended times. The number of protons in the source is estimated for various times based on the propagation model. Moreover, this value is in qualitative and quantitative agreement with the number of protons required to generate the observed gamma-ray emission for the June 15, 1991 event (and in qualitative agreement for the June 11, 1991 event). This provides evidence that processes of prolonged trapping and/or acceleration of protons in coronal structures may be possible in other such events.

Monitoring oxidation of chlorinated ethenes by permanganate in groundwater using stable isotopes: laboratory and field studies.

Permanganate injection is increasingly applied for in situ destruction of chlorinated ethenes in groundwater. This laboratory and field study demonstrates the roles that carbon isotope analysis can play in the assessment of oxidation of trichloroethene (TCE) by permanganate. In laboratory experiments a strong carbon isotope fractionation was observed during oxidation of TCE with similar isotopic enrichment factors (-25.1 to -26.8 per thousand) for initial KMnO4 concentrations between 67 and 1,250 mg/L. At the field site, a single permanganate injection episode was conducted in a sandy aquifer contaminated with TCE as dense nonaqueous liquid (DNAPL). After injection, enriched delta13C values of up to +204% and elevated Cl- concentrations were observed at distances of up to 4 m from the injection point. Farther away, the Cl- increased without any change in delta13C of TCE suggesting that Cl- was not produced locally but migrated to the sampling point Except for the closest sampling location to the injection point, the delta13C rebounded to the initial 613C again, likely due to dissolution of DNAPL Isotope mass balance calculations made it possible to identify zones where TCE oxidation continued to occur during the rebound phase. The study indicates that delta13C values can be used to assess the dynamics between TCE oxidation and dissolution and to locate zones of oxidation of chlorinated ethenes that cannot be identified from the Cl- distribution alone.

X‐Ray Spectral Variability Signatures of Flares in BL Lacertae Objects

We are presenting a detailed parameter study of the time-dependent electron injection and kinematics and the self-consistent radiation transport in jets of intermediate and low-frequency peaked BL Lac objects. Using a time-dependent, combined synchrotron-self-Compton and external-Compton jet model, we study the influence of variations of several essential model parameters, such as the electron injection compactness, the relative contribution of synchrotron to external soft photons to the soft photon compactness, the electron- injection spectral index, and the details of the time profiles of the electron injection episodes giving rise to flaring activity. In the analysis of our results, we focus on the expected X-ray spectral variability signatures in a region of parameter space particularly well suited to reproduce the broadband spectral energy distributions of intermediate and low-frequency peaked BL Lac objects. We demonstrate that SSC- and external-Compton dominated models for the gamma-ray emission from blazars are producing significantly different signatures in the X-ray variability, in particular in the soft X-ray light curves and the spectral hysteresis at soft X-ray energies, which can be used as a powerful diagnostic to unveil the nature of the high-energy emission from BL Lac objects.

Structure, Evolution, and Nucleosynthesis of Primordial Stars

(abridge version) The evolution of population III stars (Z=0) is followed from the pre-main sequence phase up to the AGB phase for intermediate-mass stars and up to C ignition in more massive stars...We find that, thanks to the development of mixing episodes (carbon injections) at the beginning of the AGB phase, the carbon abundance of the 1, 1.5, 2, 3, 4 and 5Mo models is significantly increased in the envelope. This process then allows low- and intermediate-mass stars to achieve a ``standard'' thermally pulsing AGB phase... In the 7Mo model, the CNO envelope abundance following the second dredge-up is so large that the star does not experience the carbon injection episode and follows a more standard thermally pulsing AGB evolution. Our computations also indicate that, thanks to a small overshooting at the base of the convective envelope, the third dredge-up is already operating in stars with M >~1.5 Mo after a few pulses, and that by the end of our modeling, hot bottom burning is activated in stars more massive than ~ 2Mo. This evolutionary behavior suggests that primordial low- and intermediate stars could have been significant contributors to the production of primary 12C, 14N, and may have contributed to some extent to the production of Mg and Al and possibly s-elements (despite the lack of iron seeds) in the early universe.

Constraints for timing of extensional tectonics in the western margin of the Red Sea in Eritrea

Recent work on asthenosphere–lithosphere coupling reinforces past observations that active and passive rifting models do not adequately describe real rifts. There remains insufficient knowledge of fundamental controls on rift architecture. In the actively extending Red Sea margin of eastern Eritrea, which lies at the Red Sea/Danakil–Gulf of Aden and the East African rift triple junction zone, the geometry and kinematics of extension are complex and poorly defined due to large data gaps. Extension and sea-floor spreading in both the Red Sea and Gulf of Aden have influenced the Neogene tectonic development of Eritrea but many of the structures have Pan-African origins and do not follow normal plate opening geometries. To constrain the rifting history in eastern Eritrea, apatite fission-track thermochronologic data were measured for 22 Pan-African rock samples. Results identify late Oligocene–early Miocene cooling coincident with extension and erosion along the conjugate margin in Yemen. A younger age group, confined to Mt Ghedem, relates to an episode of fault reactivation and dyke injection that began ∼10 Ma coincident with rotation of the nearby Danakil block. Initially this was driven by onset of sea-floor spreading in the Gulf of Aden and later, in the Pliocene, aided by northward rifting in the Afar depression concomitant with spreading in the Red Sea. These different processes highlight the complex linkage between different extensional events and rift architecture.