A highly-ionized absorber as a new explanation for the spectral changes during dips from X-ray binaries

Until now, the spectral changes observed from persistent to dipping intervals in dipping low-mass X-ray binaries were explained by invoking progressive and partial covering of an extended emission region. Here, we propose a novel and simpler way to explain these spectral changes, which does not require any partial covering and hence any extended corona, and further has the advantage of explaining self-consistently the spectral changes both in the continuum and the narrow absorption lines that are now revealed by XMM-Newton. In 4U 1323-62, we detect Fe XXV and Fe XXVI absorption lines and model them for the first time by including a complete photo-ionized absorber model rather than individual Gaussian profiles. We demonstrate that the spectral changes both in the continuum and the lines can be simply modeled by variations in the properties of the ionized absorber. From persistent to dipping the photo-ionization parameter decreases while the equivalent hydrogen column density of the ionized absorber increases. In a recent work (see Diaz Trigo et al. in these proceedings), we show that our new approach can be successfully applied to all the other dipping sources that have been observed by XMM-Newton.Comment: 5 pages, 5 figures, to appear in the proceedings of "The X-ray Universe 2005", San Lorenzo de El Escorial (Spain), 26-30 September 200

Modeling and source apportionment of diesel particulate matter

The fine and ultra fine sizes of diesel particulate matter (DPM) are of greatest health concern. The composition of these primary and secondary fine and ultra fine particles is principally elemental carbon (EC) with adsorbed organic compounds, sulfate, nitrate, ammonia, metals, and other trace elements. The purpose of this study was to use an advanced air quality modeling technique to predict and analyze the emissions and the primary and secondary aerosols concentrations that come from diesel-fueled sources (DFS). The National Emissions Inventory for 1999 and a severe southeast ozone episode that occurred between August and September 1999 were used as reference. Five urban areas and one rural area in the Southeastern US were selected to compare the main results. For urban emissions, results showed that DFS contributed (77.9% ± 8.0) of EC, (16.8% ± 8.2) of organic aerosols, (14.3% ± 6.2) of nitrate, and (8.3% ± 6.6) of sulfate during the selected episodes. For the rural site, these contributions were lower. The highest DFS contribution on EC emissions was allocated in Memphis, due mainly to diesel non-road sources (60.9%). For ambient concentrations, DFS contributed (69.5% ± 6.5) of EC and (10.8% ± 2.4) of primary anthropogenic organic aerosols, where the highest DFS contributions on EC were allocated in Nashville and Memphis on that episode. The DFS contributed (8.3% ± 1.2) of the total ambient PM2.5 at the analyzed sites. The maximum primary DPM concentration occurred in Atlanta (1.44 μg/m3), which was 3.8 times higher than that from the rural site. Non-linearity issues were encountered and recommendations were made for further research. The results indicated significant geographic variability in the EC contribution from DFS, and the main DPM sources in the Southeastern U.S. were the non-road DFS. The results of this work will be helpful in addressing policy issues targeted at designing control strategies on DFS in the Southeastern U.S

Health risk assessment posed by primary diesel particulate matter and vapor air toxics in Southeastern US

Air toxics concentrations and health effects that come from different sources emission scenarios by linking Models-3/CMAQ and cancer risk assessment were predicted. The year 1999 was used to emissions inventory and the year 2003 for meteorological data and modeling performance. To demonstrate the system's effectiveness, this study was performed on priority mobile sources air toxics; benzene, 1,3-butadiene, formaldehyde, acetaldehyde, and diesel particulate matter (DPM). The analysis was applied mainly to Nashville in the Southeastern US. Ten emissions scenarios were selected to compare the principal results. DPM posed a cancer risk that was 4.2 times higher than the combined total cancer risk from all other four air toxics. Those high cancer risk levels were due mainly to non-road sources (57.9%). For the on-road diesel fueled sources, the principal reductions were due to the DPM generated by heavy duty diesel vehicles. The main on-road reductions were due to the air toxics generated by gasoline light duty vehicles, principally benzene and 1,3-butadiene. Reducing ambient DPM concentrations would lead to improvement in human health more than other air toxics, indicating that better technologies and regulations must be applied to the mobile diesel engines, principally, over non-road diesel sources. This is an abstract of a paper presented at the AWMA's 99th Annual Conference and Exhibition (New Orleans, LA 6/20-23/2006)

Emission Scenarios and the Health Risks Posed by Priority Mobile Air Toxics in an Urban to Regional Area: An Application in Nashville, Tennessee

Toxic air pollutants, also known as hazardous air pollutants, are those that are known or suspected to cause cancer or other serious health effects, such as birth defects or adverse environmental outcomes. The aim of this research was to predict air toxics related health risks due to different emission scenarios by linking Models-3/CMAQ and cancer risk assessments. To demonstrate the effectiveness of this approach, this study was performed on the priority mobile source air toxics (PMSAT) of benzene, 1,3-butadiene, formaldehyde, acetaldehyde, and diesel particulate matter (DPM), based on data from 2003. The analysis was carried out in the eastern US, and mainly in Nashville, TN. Ten emissions scenarios were examined, including a 2020 scenario with the effects of on-road mobile source regulations. The results show that DPM poses a cancer risk that is 4.2 times higher than the combined total cancer risk from all of four other PMSAT. These high cancer risk levels are mainly due to non-road sources (57.9%). The main cancer risk from acetaldehyde, benzene, formaldehyde, and 1,3-butadiene (4HAPs) is due to biogenic sources, which account for 32.2% of this risk, although these cannot be controlled. Excluding DPM, the main on-road cancer risk contribution was due to the air toxics generated by gasoline light duty vehicles (LDVs), principally benzene and 1,3-butadiene. The scenario for 2020 showed reductions in the adverse health effects related to DPM and 4HAPs of 32.8 and 19.4%, respectively. This research provides strong evidence that reducing ambient DPM concentrations will lead to greater improvements in human health than other air toxics, indicating that better technologies and regulations must be applied to mobile diesel engines, as these have more significant adverse health effects than non-road diesel sources

A hybrid ARIMA and artificial neural networks model to forecast particulate matter in urban areas: The case of Temuco, Chile

Air quality time series consists of complex linear and non-linear patterns and are difficult to forecast. Box-Jenkins Time Series (ARIMA) and multilinear regression (MLR) models have been applied to air quality forecasting in urban areas, but they have limited accuracy owing to their inability to predict extreme events. Artificial neural networks (ANN) can recognize non-linear patterns that include extremes. A novel hybrid model combining ARIMA and ANN to improve forecast accuracy for an area with limited air quality and meteorological data was applied to Temuco, Chile, where residential wood burning is a major pollution source during cold winters, using surface meteorological and PM10 measurements. Experimental results indicated that the hybrid model can be an effective tool to improve the PM10 forecasting accuracy obtained by either of the models used separately, and compared with a deterministic MLR. The hybrid model was able to capture 100% and 80% of alert and pre-emergency episodes, respectively. This approach demonstrates the potential to be applied to air quality forecasting in other cities and countries

Clinical assessment of pain in spanish neonatal intensive care units

[Resumen] Introducción. Las escalas clínicas son hoy en día el mejor método para evaluar el dolor en el neonato, dada la imposibilidad de autorreporte en este grupo de edad. Se diseñó un estudio con el objetivo de determinar las prácticas actuales en relación con la valoración clínica del dolor en España y los factores asociados al uso de escalas clínicas. Métodos. El estudio es de tipo observacional, longitudinal y prospectivo. Participaron 30 unidades y se reclutó a 468 neonatos. Resultados. Solo 13 unidades (43,3%) disponían de protocolos de valoración del dolor. Se evaluó el dolor con una escala en 78 neonatos (16,7%, IC del 95%, 13,1-20,1) y el número medio de valoraciones del dolor por paciente y día de estancia fue de 2,3±4,8, con una mediana de 0,75. Del total de 7.189 días-paciente estudiados, 654 (9,1%) conllevaron al menos una valoración del dolor. Veinte unidades (66,7%) no realizaron evaluación del dolor con una escala clínica en ningún paciente. Entre las que sí lo hicieron, se observó una gran variabilidad en el porcentaje de pacientes en los que se evaluó el dolor y en las escalas utilizadas. La escala CRIES (C-Crying; R-Requires increased oxygen administration; I-Increased vital signs; E-Expression; S-Sleeplessness) fue la que se usó en más unidades. En el análisis multivariante solo la ventilación mecánica invasiva se asoció a recibir valoración del dolor con una escala (OR 1,46, p=0,042). Discusión. La mayoría de los neonatos ingresados en cuidados intensivos en España no recibe una valoración del dolor. Muchas unidades todavía no utilizan rutinariamente las escalas clínicas y entre las que las utilizan existe una gran variabilidad. Estos resultados pueden servir de base para la elaboración de guías nacionales al respecto del dolor en el neonato.[Abstract] Introduction. Clinical scales are currently the best method to assess pain in the neonate, given the impossibility of self-report in this age group. A study is designed with the aim of determining the current practices as regards the clinical assessment of pain in Spanish Neonatal Units and the factors associated with the use of clinical scales. Methods. A prospective longitudinal observational study was conducted. A total of 30 Units participated and 468 neonates were included. Results. Only 13 Units (43.3%) had pain assessment protocols. Pain was evaluated with a scale in 78 neonates (16.7%, 95% CI; 13.1-20.1) and the mean number of pain assessments per patient and per day was 2.3 (Standard Deviation; 4.8), with a median of 0.75. Of the total number of 7,189 patient-days studied, there was at least one pain assessment in 654 (9.1%). No pain assessment was performed with a clinical scale on any patient in 20 (66.7%) Units. Among those that did, a wide variation was observed in the percentage of patients in whom pain was assessed, as well as in the scales used. The CRIES (C-Crying; R-Requires increased oxygen administration; I-Increased vital signs; E-Expression; S-Sleeplessness) scale was that used in most Units. In the multivariate analysis, only invasive mechanical ventilation was associated with receiving a pain assessment with a scale (OR 1.46, P=.042). Discussion. The majority of neonates admitted into Intensive Care in Spain do not receive a pain assessment. Many units still do not routinely use clinical scales, and there is a wide variation between those that do use them. These results could serve as a basis for preparing national guidelines as regards pain in the neonate

Wormholes and Ringholes in a Dark-Energy Universe

The effects that the present accelerating expansion of the universe has on the size and shape of Lorentzian wormholes and ringholes are considered. It is shown that, quite similarly to how it occurs for inflating wormholes, relative to the initial embedding-space coordinate system, whereas the shape of the considered holes is always preserved with time, their size is driven by the expansion to increase by a factor which is proportional to the scale factor of the universe. In the case that dark energy is phantom energy, which is not excluded by present constraints on the dark-energy equation of state, that size increase with time becomes quite more remarkable, and a rather speculative scenario is here presented where the big rip can be circumvented by future advanced civilizations by utilizing sufficiently grown up wormholes and ringholes as time machines that shortcut the big-rip singularity.Comment: 11 pages, RevTex, to appear in Phys. Rev.

The effect of switching mobile sources to natural gas on the ozone in the great smoky mountains national park

Mobile sources are among the largest contributors of NOx in the Great Smoky Mountains National Park region (GSMNP). In 2001, these sources contributed 45% of NOx emissions. From 1990 to 2001, the growth of vehicle miles traveled (VMT) increased 60% and 55% in neighboring Sevier and Blount counties respectively. These emissions combined with the high volatile organic compounds (VOC) emissions in the Southeast area have caused the ozone ground level concentration to be as high as some major metropolitan areas in the summer season. In 2001, the maximum 8-hr ozone concentration inside the park was 103 parts per billion. In response to high ozone levels in other areas, federal, state, and local governments are promoting the use of alternative, clean, and reformulated fuel vehicles as a means to improve local air pollution. One of these fuels is compressed natural gas (CNG). The purpose of this project was to use USEPA's CMAQ system in order to model the air quality and compare the ozone ground level formation in the GSMNP from light duty vehicles (LDVs) operating with 100% CNG within 100 miles around GSMNP. A severe southeast ozone episode between August and September 1999 was used as a reference and 2004 was used as a future case. Results showed that LDVs fueled with 100% CNG in the domain could reduce ozone level by 10% and 8% for 1-hr and 8-hr ozone formation respectively in the GSMNP on the modeled time period. Scavenging occurred around the GSMNP in the morning time during the selected episode

Channel waveguides and Mach-Zehnder structures on RbTiOPO₄ by Cs⁺ ion exchange

Cs+ ion exchange in RbTiOPO4 and (Yb,Nb):RTP/RTP(001) has been used to locally increase the refractive indices for waveguide circuit fabrication. Ti masks were fabricated on RTP samples by conventional photolithography. Cs+ exchange was done using a CsNO3 melt at 698 K during 2 h. Elemental analysis confirms an Cs+ profile with a variable depth. Apparently the Cs+ exchange is disfavored in the doped epitaxial sample. The refractive index variation is higher for nz than for nx,y. Near-field images of the guided modes at 633, 1064 and 1520 nm were recorded. The optical characterization shows propagation losses of 5 dB/cm at 1520 nm

Late-time cosmology in (phantom) scalar-tensor theory: dark energy and the cosmic speed-up

We consider late-time cosmology in a (phantom) scalar-tensor theory with an exponential potential, as a dark energy model with equation of state parameter close to -1 (a bit above or below this value). Scalar (and also other kinds of) matter can be easily taken into account. An exact spatially-flat FRW cosmology is constructed for such theory, which admits (eternal or transient) acceleration phases for the current universe, in correspondence with observational results. Some remarks on the possible origin of the phantom, starting from a more fundamental theory, are also made. It is shown that quantum gravity effects may prevent (or, at least, delay or soften) the cosmic doomsday catastrophe associated with the phantom, i.e. the otherwise unavoidable finite-time future singularity (Big Rip). A novel dark energy model (higher-derivative scalar-tensor theory) is introduced and it is shown to admit an effective phantom/quintessence description with a transient acceleration phase. In this case, gravity favors that an initially insignificant portion of dark energy becomes dominant over the standard matter/radiation components in the evolution process.Comment: LaTeX file, 48 pages, discussion of Big Rip is enlarged, a reference is adde