Standard Conversion Factor Research Articles

Qualification of an enzyme-linked immunosorbent assay for quantification of anti-Vi IgG in human sera.

Effective vaccines against Salmonella Typhi, targeting the Vi capsular polysaccharide, have been developed and are being introduced into routine immunization in endemic countries. Vi conjugated vaccines are also being tested in new multi-component vaccine formulations. Simple, high-throughput and cost-effective assays to quantify Vi-specific IgG in clinical sera are needed. In this study we present the development and qualification of a new anti-Vi ELISA with continuous readout, which expresses results as ELISA Unit/mL (EU/mL). We have qualified the assay in terms of precision, linearity and specificity, demonstrating performance in line with a commercially available anti-Vi ELISA. We have also calibrated the assay against the 16/138 anti-Vi international standard and established conversion factor between EU/mL and international units/mL, to allow comparability of results across studies. In summary, this new assay met all the suitability criteria and is being used to evaluate anti-Vi responses in clinical studies.

Development and Assessment of an Artificial Intelligence-Based Tool for Ptosis Measurement in Adult Myasthenia Gravis Patients Using Selfie Video Clips Recorded on Smartphones

Introduction: Myasthenia gravis (MG) is a rare autoimmune disease characterized by muscle weakness and fatigue. Ptosis (eyelid drooping) occurs due to fatigue of the muscles for eyelid elevation and is one symptom widely used by patients and healthcare providers to track progression of the disease. Margin reflex distance 1 (MRD1) is an accepted clinical measure of ptosis and is typically assessed using a hand-held ruler. In this work, we develop an AI model that enables automated measurement of MRD1 in self-recorded video clips collected using patient smartphones. Methods: A 3-month prospective observational study collected a dataset of video clips from patients with MG. Study participants were asked to perform an eyelid fatigability exercise to elicit ptosis while filming “selfie” videos on their smartphones. These images were collected in nonclinical settings, with no in-person training. The dataset was annotated by non-clinicians for (1) eye landmarks to establish ground truth MRD1 and (2) the quality of the video frames. The ground truth MRD1 (in millimeters, mm) was calculated from eye landmark annotations in the video frames using a standard conversion factor, the horizontal visible iris diameter of the human eye. To develop the model, we trained a neural network for eye landmark detection consisting of a ResNet50 backbone plus two dense layers of 78 dimensions on publicly available datasets. Only the ResNet50 backbone was used, discarding the last two layers. The embeddings from the ResNet50 were used as features for a support vector regressor (SVR) using a linear kernel, for regression to MRD1, in mm. The SVR was trained on data collected remotely from MG patients in the prospective study, split into training and development folds. The model’s performance for MRD1 estimation was evaluated on a separate test fold from the study dataset. Results: On the full test fold (N = 664 images), the correlation between the ground truth and predicted MRD1 values was strong (r = 0.732). The mean absolute error was 0.822 mm; the mean of differences was −0.256 mm; and 95% limits of agreement (LOA) were −0.214–1.768 mm. Model performance showed no improvement when test data were gated to exclude “poor” quality images. Conclusions: On data generated under highly challenging real-world conditions from a variety of different smartphone devices, the model predicts MRD1 with a strong correlation (r = 0.732) between ground truth and predicted MRD1.

Are insects a good source of protein for humans?

When insects are introduced as a novel protein source in human diets, we need to understand the protein quality to compare their nutritional value with other foods. Protein quality assessment methods are based on evaluation of the ability of the protein to meet the amino acid (AA) requirements of the human body. Most available data comes from animal models, either in rats or pigs. The limited available data supports edible insects as a high-quality protein source for human consumption. The farmed insect species considered relevant as an alternative protein source are generally of good quality, and the protein quality of the vast diversity of insect species harvested from the wild across continents are likely to be sources of good quality, though this remains to be assessed. For methodological considerations, the recommended DIAAS (digestible indispensable AA score) method relies on accurately determining the total protein content. When determining total protein based on total nitrogen (N), using the standard conversion factor of 6.25 which disregards the non-protein N in insects, the protein quality is underestimated in comparison with other animal-source foods, such as meat and dairy.

Opioid Utilization After Scoliosis Surgery is Greater in Marfan Syndrome Than Adolescent Idiopathic Scoliosis.

Retrospective matched case cohort. Compare postoperative opioid utilization and prescribing behaviors between patients with Marfan syndrome (MFS) and adolescent idiopathic scoliosis (AIS) after posterior spinal fusion (PSF). Opioids are an essential component of pain management after PSF. However, due to the potential for opioid use disorder and dependence, current analgesic strategies aim to minimize their use, especially in younger patients. Limited information exists on opioid utilization after PSF for syndromic scoliosis. Twenty adolescents undergoing PSF with MFS were matched with patients with AIS (ratio, 1:2) by age, sex, degree of spinal deformity, and the number of vertebral levels fused. Inpatient and outpatient pharmaceutical data were reviewed for the quantity and duration of opioid and adjunct medications. Prescriptions were converted to morphine milligram equivalents (MMEs) using CDC's standard conversion factor. Compared with patients with AIS, patients with MFS had significantly greater total inpatient MME use (4.9 vs . 2.1 mg/kg, P ≤ 0.001) and longer duration of intravenous patient-controlled anesthesia (3.4 vs . 2.5 d, P = 0.001). Within the first 2 postop days, MFS patients had more patient-controlled anesthesia boluses (91 vs . 52 boluses, P = 0.01) despite similar pain scores and greater use of adjunct medications. After accounting for prior opioid use, MFS was the only significant predictor of requesting an opioid prescription after discharge (odds ratio: 4.1, 95% CI: 1.1-14.9, P = 0.03). Patients with MFS were also more likely to be discharged with a more potent prescription (1.0 vs . 0.72 MME per day/kg, P ≤ 0.001) and to receive a longer-duration prescription (13 vs . 8 d, P = 0.005) with a greater MME/kg (11.6 vs . 5.6 mg/kg, P ≤ 0.001) as outpatients. Despite a similar intervention, patients with MFS and AIS seem to differ in their postoperative opioid usage after PSF, presenting an opportunity for further research to assist clinicians in better anticipating the analgesic needs of individual patients, particularly in light of the ongoing opioid epidemic.

Farklı LED ışıklar altında yetiştirilen köksüz su mercimeğinin (Wolffia arrhiza) Dumas yöntemi kullanılarak ham protein içeriğinin belirlenmesi

Rootless duckweed (Wolffia spp.) has the potential high-protein food source for humans. Wolffia is a member of the Lemnaceae family and is the world's smallest spermatophyte, with reduced roots, stems, and leaves. Scientific research on Wolffia species is relatively new, and this species is believed to be rare in Turkey. The phytochemicals and nutritional composition of plants are significantly affected by environmental factors in the natural or cultivated medium. In this study, Wolffia arrhiza was collected and cultured from a local area in Yeşilırmak Delta (Samsun) grown under controlled conditions using different LED lights. The Dumas method was used to determine the amount of crude protein. The protein content, calculated by multiplying the nitrogen (%) content by the standard conversion factor 6.25, was also evaluated by using different conversion factors in the literature. The results showed that rootless duckweed can be successfully grown under artificial lighting conditions with different light spectrums. The protein content of rootless duckweed, which was around 10% in the natural environment, increased considerably under red LED light (41.6% protein). The effect of different lights on protein content of W. arrhiza was observed as red LED > blue LED > purple LED > fluorescent. With its high protein content, environmentally friendly and sustainable production, Wolffia has the potential to quickly take place in the plant-based protein and functional food market as an alternative to traditional crops in the near future.

Properties of molecular gas in galaxies in the early and mid stages of interaction. II. Molecular gas fraction

Abstract We have investigated properties of the interstellar medium in interacting galaxies in early and mid stages using mapping data of 12CO(J = 1–0) and H i. Assuming the standard CO–H2 conversion factor, we found no difference in molecular gas mass, atomic gas mass, and total gas mass (the sum of atomic and molecular gas mass) between interacting galaxies and isolated galaxies. However, interacting galaxies have a higher global molecular gas fraction $f_{\rm {mol}}^{\rm {global}}$ (the ratio of molecular gas mass to total gas mass averaged over a whole galaxy) at 0.71 ± 0.15 than isolated galaxies (0.52 ± 0.18). The distribution of the local molecular gas fraction fmol, the ratio of the surface density of molecular gas to that of the total gas, is different from the distribution in typical isolated galaxies. By a pixel-to-pixel comparison, isolated spiral galaxies show a gradual increase in fmol along the surface density of total gas until it is saturated at 1.0, while interacting galaxies show no clear relation. We performed pixel-to-pixel theoretical model fits by varying metallicity and external pressure. According to the model fitting, external pressure can explain the trend of fmol in the interacting galaxies. Assuming half of the standard CO–H2 conversion factor for interacting galaxies, the results of pixel-to-pixel theoretical model fitting get worse than adopting the standard conversion factor, although $f_{\rm {mol}}^{\rm {global}}$ of interacting galaxies (0.62 ± 0.17) becomes the same as in isolated galaxies. We conclude that external pressure occurs due to the shock prevailing over a whole galaxy or due to collisions between giant molecular clouds even in the early stage of the interaction. The external pressure accelerates an efficient transition from atomic gas to molecular gas. Regarding the chemical timescale, high fmol can be achieved at the very early stage of interaction even if the shock induced by the collision of galaxies ionizes interstellar gas.

Methodological biases in estimates of macroalgal macromolecular composition

AbstractInterest surrounding the use of macroalgae macromolecules for food products, biofuels, or other industrial applications is growing. As researchers search for macroalgae with especially high protein, lipid, carbohydrate or fibre content, the demand for a suite of standardized and unbiased methods for quantifying macroalgae macromolecules increases. Using data from available scientific literature, we evaluated the biases of the major methods used to determine macroalgal macromolecular content, as well as the sample drying methods employed. We found that drying at room temperature prior to analysis resulted in the highest estimates of protein and carbohydrate, and that freeze‐drying provided the highest estimates of lipid. Using nitrogen content and the standard conversion factor to calculate protein in macroalgae (N × 6.25 method) overestimates protein content compared to protein assays such as the Bradford () or Lowry () assays. The Bligh and Dyer () lipid extraction method was found to have a yield nearly two‐fold higher than other standard methods. For carbohydrates, the By Difference and Prosky et al. () methods provide estimates up to five‐fold higher than other common methods used to determine carbohydrate and fibre. Based on these results we recommend using protein assays as opposed to nitrogen content assays to determine protein content, the Bligh and Dyer lipid extraction method for lipids, and the By Difference and Prosky method for carbohydrate and fibre, respectively.

ALMA hints at the existence of an unseen reservoir of diffuse molecular gas in the Galactic bulge

Aims. We aim to understand the unexpected presence of mm-wave molecular absorption at −200 km s-1<v<−140 km s-1 in a direction that is well away from regions of the Galactic bulge where CO emission at such velocities is prominent. Methods. We compared 89 GHz Cycle 2 ALMA absorption spectra of HCO+, HCN, and HNC toward the extragalactic continuum source B1741-312 at l = −2.14°, b = −1.00° with existing CO, H I, and dust emission and absorption measurements. We placed the atomic and molecular gas in the bulge and disk using circular and non-circular galactic kinematics, deriving N(H I) from a combination of 21 cm emission and absorption and we derive N(H2) from scaling of the HCO+ absorption. We then inverted the variation of near-IR reddening E(J−K) with distance modulus and scale E(J−K) to a total gas column density N(H) that may be compared to N(H I) and N(H2). Results. At galactocentric radii Rgal> 1.5 kpc, conventional measures such as the standard CO-H2 conversion factor and locally observed N(HCO+)/N(H2) ratio separately imply that H I and H2 contribute about equally to N(H), and the gas-derived N(H) values are in broad agreement with those derived from E(J−K). Within the Galactic bulge at Rgal< 1.5 kpc, H I contributes less than 10% of the material inferred from E(J−K), so that the molecular absorption detected here is needed to understand the extinction.

The anatomy of the Orion B giant molecular cloud: A local template for studies of nearby galaxies

We aim to develop the Orion B Giant Molecular Cloud (GMC) as a local template for interpreting extra-galactic molecular line observations. We use the wide-band receiver at the IRAM-30m to spatially and spectrally resolve the Orion B GMC. The observations cover almost 1 square degree at 26" resolution with a bandwidth of 32 GHz from 84 to 116 GHz in only two tunings. Among the mapped spectral lines are the 12CO, 13CO, C18O, C17O, HCN, HNC, 12CN, CCH, HCO+, N2H+ (1-0), and 12CS, 32SO, SiO, c-C3H2, CH3OH (2-1) transitions. We introduce the molecular anatomy of the Orion B GMC, including relations between line intensities and gas column density or far-UV radiation fields, and correlations between selected line and line ratios. We also obtain a dust-traced gas mass that is less than about one third the CO-traced mass, using the standard Xco conversion factor. The presence of overluminous CO can be traced back to the dependence of the CO intensity on UV illumination. In fact, while most lines show some dependence on the UV radiation field, CN and CCH are the most sensitive. Moreover dense cloud cores are almost exclusively traced by N2H+. Other traditional high density tracers, such as HCN (1-0), are also easily detected in extended translucent regions at a typical density of about 500 H2 cm-3. In general, we find no straightforward relation between line critical density and the fraction of the line luminosity coming from dense gas regions. Our initial findings demonstrate that the relations between line (ratio) intensities and environment in GMCs are more complicated than often assumed. Sensitivity (i.e., the molecular column density), excitation, and above all chemistry contribute to the observed line intensity distributions. They must be considered together when developing the next generation of extra-galactic molecular line diagnostics of mass, density, temperature and radiation field.

Solid cancer incidence among Chinese medical diagnostic x-ray workers, 1950-1995: Estimation of radiation-related risks.

The objective of this study was to estimate solid cancer risk attributable to long-term, fractionated occupational exposure to low doses of ionizing radiation. Based on cancer incidence for the period 1950-1995 in a cohort of 27,011 Chinese medical diagnostic X-ray workers and a comparison cohort of 25,782 Chinese physicians who did not use X-ray equipment in their work, we used Poisson regression to fit excess relative risk (ERR) and excess absolute risk (EAR) dose-response models for incidence of all solid cancers combined. Radiation dose reconstruction was based on a previously published method that relied on simulating measurements for multiple X-ray machines, workplaces and working conditions, information about protective measures, including use of lead aprons, and work histories. The resulting model was used to estimate calendar year-specific badge dose calibrated as personal dose equivalent (Sv). To obtain calendar year-specific colon doses (Gy), we applied a standard organ conversion factor. A total of 1,643 cases of solid cancer were identified in 1.45 million person-years of follow-up. In both ERR and EAR models, a statistically significant radiation dose-response relationship was observed for solid cancers as a group. Averaged over both sexes, and using colon dose as the dose metric, the estimated ERR/Gy was 0.87 (95% CI: 0.48, 1.45), and the EAR was 22 per 10(4)PY-Gy (95% CI: 14, 32) at age 50. We obtained estimates of the ERR and EAR of solid cancers per unit dose that are compatible with those derived from other populations chronically exposed to low dose-rate occupational or environmental radiation.

Star formation efficiency along the radio jet in Centaurus A

Centaurus A is the most nearby powerful AGN, widely studied at all wavelengths. Molecular gas has been found in the halo at a distance of ~20 kpc from the galaxy centre, associated with HI shells. The molecular gas lies inside some IR and UV bright star-forming filaments that have recently been observed in the direction of the radio jets. These archival data show that there is dust and very weak star formation on scales of hundreds of parsecs. On top of analysing combined archival data, we have performed searches of HCN(1-0) and HCO+(1-0) emission with ATCA at the interaction of the northern filaments and the HI shell of Cen A. Measuring the dense gas is another indicator of star formation efficiency inside the filaments. However, we only derived upper limits of 1.6x10^3 K.km/s.pc^2 at 3 sigma in the synthesised beam of 3.1". We also compared the CO masses with the SFR estimates in order to measure a star formation efficiency. Using a standard conversion factor leads to long depletion times (7 Gyr). We then corrected the mass estimates from metallicity effect by using gas-to-dust mass ratio as a proxy. From MUSE data, we estimated the metallicity spread (0.4-0.8 Zsun) in the filament, corresponding to gas-to-dust ratios of ~200-400. The CO/H2 conversion ratio is corrected for low metallicity by a factor between 1.4 and 3.2. Such a low-metallicity correction leads to even more massive clouds with higher depletion times (16 Gyr). We finally present ALMA observations that detect 3 unresolved CO(2-1) clumps of size <37x21 pc and masses around 10^4 Msun. The velocity width of the CO emission line is ~10 km/s, leading to a rather high virial parameter. This is a hint of a turbulent gas probably powered by kinetic energy injection from the AGN jet/wind and leading to molecular gas reservoir not forming star efficiently.

Estimation of the Risk of Cancer Associated with Pediatric Cranial Computed Tomography

Background: The role of Computed Tomography (CT) in the medical diagnosis of diseases has greatly expanded, despite the potential risk of cancer following exposures to ionising radiation (XRay) from this modality. This risk is particularly of great concern in children, who are more radiosensitive and have many years to manifest radiation effect than adults. Aims: To estimate risk of cancer induction from Pediatric cranial CT. Materials and Methods: A total of 203 patients, who were referred from various pediatric clinics and wards for cranial CT in a teaching hospital in the South Western Nigeria between the year 2011 and 2013 were considered. All patients were grouped into four age (year) groups: less than 1, 1-5, 5-10 and 10-15. A mathematical method was used to estimate the risk of cancer from the Original Research Article Atalabi et al.; BJMMR, 9(10): 1-7, 2015; Article no.BJMMR.18079 2 effective dose(ED) calculated from volume computed tomography dose index (CTDIvol), dose length product (DLP) and standard conversion factor. Results: The range of CTDIvol (mGy) received by all patients was 10–250 mGy while majority of the patients received 50–100. The range of DLP (mGy.cm) received by all patients and majority of patients was 500–5000 and 2001–2500 respectively. The range of ED (mSv) received by all patients and majority of the patients was 1–25 and 5–10 respectively. The risk estimated with respect to patients’ age showed that patient in the age group 1–5 years have the highest risk of cancer induction while the risk based on gender showed no significant difference. Conclusion: Over 60% of pediatric patients received more than the recommended values of CTDIvol, DLP and ED from cranial CT. Urgent steps must be taken to ensure compliant with international recommended precautions for dose reduction in pediatric medical imaging.

The Recommendation of how to Improve the Accuracy and Feasibility of Eco-Compensation Standard in Coal Mine Areas

Ecological compensation mechanism is an important guarantee of the protection and restoration of mine ecological environment, and accuracy and feasibility of compensation standard is the key for the establishment of ecological compensation mechanism. Based on the literature review and the regional ecological compensation mechanism practice, this paper summarized the domestic and foreign research progress of ecological compensation in mining area and pointed out some problems existing in the field, and then suggested that principle of landscape planning, geographic information technology as well as the compensation standard conversion factor should be used comprehensively to solve the problem from the perspectives of calculation method, data acquisition means and the concept of compensation standards.

A search of CO emission lines in blazars: the low molecular gas content of BL Lac objects compared to quasars

BL Lacertae (Lac) objects that are detected at very-high energies (VHE) are of fundamental importance to study multiple astrophysical processes, including the physics of jets, the properties of the extragalactic background light and the strength of the intergalactic magnetic field. Unfortunately, since most blazars have featureless optical spectra that preclude a redshift determination, a substantial fraction of these VHE extragalactic sources cannot be used for cosmological studies. To assess whether molecular lines are a viable way to establish distances, we have undertaken a pilot program at the IRAM 30m telescope to search for CO lines in three BL Lac objects with known redshifts. We report a positive detection of M_H2 ~ 3x10^8 Msun toward 1ES 1959+650, but due to the poor quality of the baseline, this value is affected by a large systematic uncertainty. For the remaining two sources, W Comae and RGB J0710+591, we derive 3sigma upper limits at, respectively, M_H2 < 8.0x10^8 Msun and M_H2 < 1.6x10^9 Msun, assuming a line width of 150 km/s and a standard conversion factor alpha=4 M_sun/(K km/s pc^2). If these low molecular gas masses are typical for blazars, blind redshift searches in molecular lines are currently unfeasible. However, deep observations are still a promising way to obtain precise redshifts for sources whose approximate distances are known via indirect methods. Our observations further reveal a deficiency of molecular gas in BL Lac objects compared to quasars, suggesting that the host galaxies of these two types of active galactic nuclei (AGN) are not drawn from the same parent population. Future observations are needed to assess whether this discrepancy is statistically significant, but our pilot program shows how studies of the interstellar medium in AGN can provide key information to explore the connection between the active nuclei and the host galaxies.

Dose assessment according to changes in algorithm in cardiac CT

The principal objective of this study was to determine the effects of the application of the adaptive statistical iterative reconstruction (ASIR) technique in combination with another two factors (body mass index (BMI) and tube potential) on radiation dose in cardiac computed tomography (CT). For quantitative analysis, regions of interest were positioned on the central region of the great coronary artery, the right coronary artery, and the left anterior descending artery, after which the means and standard deviations of measured CT numbers were obtained. For qualitative analysis, images taken from the major coronary arteries (right coronary, left anterior descending, and left circumflex) were graded on a scale of 1–5, with 5 indicating the best image quality. Effective dose, which was calculated by multiplying the value of the dose length product by a standard conversion factor of 0.017 for the chest, was employed as a measure of radiation exposure dose. In cardiac CT in patients with BMI of less than 25 kg/m2, the use of 40% ASIR in combination with a low tube potential of 100 kVp resulted in a significant reduction in the radiation dose without compromising diagnostic quality. Additionally, the combination of the 120 kVp protocol and the application of 40% ASIR application for patients with BMI higher than 25 kg/m2 yielded similar results.

Imaging diffuse clouds: bright and dark gas mapped in CO

We wish to relate the degree scale structure of galactic diffuse clouds to sub-arcsecond atomic and molecular absorption spectra obtained against extragalactic continuum background sources. To do this, we used the ARO 12m telescope to map J=1-0 CO emission at 1' resolution over 30' fields around the positions of 11 background sources occulted by 20 molecular absorption line components, of which 11 had CO emission counterparts. We compare maps of CO emission to sub-arcsec atomic and molecular absorption spectra and to the large-scale distribution of interstellar reddening. The main results are: 1) Typical covering factors of individual features at the 1 K.km/s level were 20%. 2) CO-H2 conversion factors as much as 4-5 times below the mean value N(H2)/Wco = 2e20 H2 cm^-2 /(K.km/s) are required to explain the luminosity of CO emission at/above the level of 1 K.km/s. Small conversion factors and sharp variability of the conversion factor on arcminute scales are due primarily to CO chemistry and need not represent unresolved variations in reddening or total column density. Hence, like FERMI and PLANCK we see some gas that is dark in CO and other gas in which CO is overluminous per H2. A standard CO-H2 conversion factor applies overall owing to balance between the luminosities per H2 and surface covering factors of bright and dark CO., but with wide variations.

Errors in ozone risk assessment using standard conditions for converting ozone concentrations obtained by passive samplers in mountain regions

Passive samplers are often employed to measure ozone concentrations in remote areas such as mountain forests. The potential ozone risk for vegetation is then assessed by calculating the AOT40 exposure index (accumulated hourly ozone concentration exceedances above 40 ppb, i.e. AOT40 = Σ([O(3)] - 40)Δt for any hourly ozone concentration [O(3)] > 40 ppb). AOT40 is customary calculated on the basis of ozone concentrations expressed as a volumetric mixing ratio, while lab sheets normally report ozone concentrations from passive samplers in mass units per cubic metre. Concentrations are usually converted from mass units to ppb using a standard conversion factor taking SATP (Standard Ambient Temperature and Pressure) conditions into account. These conditions, however, can vary considerably with elevation. As a consequence, the blanket application of a standard conversion factor may lead to substantial errors in reporting and mapping ozone concentrations and therefore in assessing potential ozone risk in mountain regions. In this paper we carry out a sensitivity analysis of the effects of uncertainties in estimations of air temperature (T) and atmospheric pressure (P) on the concentration conversion factor, and present two examples from two monitoring and mapping exercises carried out in the Italian Alps. We derived P and T at each site from adiabatic lapse rates for temperature and pressure and analysed the magnitude of error in concentration estimations. Results show that the concentration conversion is much more sensitive to uncertainties in P gradient estimation than to air temperature errors. The concentration conversion factor (cf) deviates 5% from the standard transformation at an elevation of 500 m asl. As a consequence, the standard estimated AOT40 at this elevation is about 13% less than the actual value. AOT40 was found to be underestimated by an average between 25% and 34% at typical elevations of mountain forest stands in the Italian Alps when a correct conversion factor for transforming ozone concentrations from μg m(-3) to ppb is not applied.

12CO, 13CO and C18O observations along the major axes of nearby bright infrared galaxies

We present simultaneous observations of 12CO, 13CO and C18O J = 1-0 emission in 11 nearby (cz < 1000km s−1) bright infrared galaxies. Both 12CO and 13CO are detected in the centers of all the galaxies, except for 13CO in NGC 3031. We have also detected C18O, CS J = 2−1 and HCO+ J = 1−0 emission in the nuclear regions of M82 and M51. These are the first systematical extragalactic detections of 12CO and its isotopes from the PMO 14m telescope. We have conducted half-beam-spaced mapping of M82 over an area of 4′ × 2.5′ and major axis mapping of NGC 3627, NGC 3628, NGC 4631 and M51. The radial distributions of 12CO and 13 CO in NGC 3627, NGC 3628 and M51 can be well fitted by an exponential profile. The 12CO/13CO intensity ratio, ℛ, decreases monotonically with the galactocentric radius in all mapped sources. The average ℛ in the center and disk of the galaxies are 9.9±3.0 and 5.6±1.9, respectively, much lower than the peculiar ℛ(∼24) found in the center of M82. The intensity ratios of 13CO/C18O, 13CO/HCO+ and 13CO/CS (either our or literature data) show little variation with galactocentric radius, in sharp contrast with the greatly varied ℛ. This supports the notion that the observed gradient in ℛ could be the result of the variations of the physical conditions across the disks. The H2 column density derived from C18O shows that the Galactic standard conversion factor (X-factor) overestimates the amount of the molecular gas in M82 by a factor of ∼2.5. These observations suggest that the X-factor in active star-forming regions (i.e., nuclear regions) should be lower than that in normal star-forming disks and the gradient in ℛ can be used to trace the variations of the X-factor.

ERRATUM: “WARM-DENSE MOLECULAR GAS IN THE ISM OF STARBURSTS, LIRGs, AND ULIRGs” (2005, ApJ, 630, 269)

The role of star formation in luminous and ultraluminous infrared galaxies is a hotly debated issue: while it is clear that starbursts play a large role in powering the IR luminosity in these galaxies, the relative importance of possible enshrouded AGNs is unknown. It is therefore important to better understand the role of star forming gas in contributing to the infrared luminosity in IR-bright galaxies. The J=3 level of 12CO lies 33K above ground and has a critical density of ~1.5 X 10^4 cm^-3. The 12CO(J=3-2) line serves as an effective tracer for warm-dense molecular gas heated by active star formation. Here we report on 12CO (J=3-2) observations of 17 starburst spirals, LIRGs and ULIRGs which we obtained with the Heinrich Hertz Submillimeter Telescope on Mt. Graham, Arizona. Our main results are the following: 1. We find a nearly linear relation between the infrared luminosity and warm-dense molecular gas such that the infrared luminosity increases as the warm-dense molecular gas to the power 0.92; We interpret this to be roughly consistent with the recent results of Gao & Solomon (2004a,b). 2. We find L_IR/M_H2 ratios ranging from ~10 to ~128 L_sun/M_sun using a standard CO-H2 conversion factor of 3 X 10^20 cm^-2 (K km s^-1)^-1. If this conversion factor is ~an order of magnitude less, as suggested in a recent statistical survey (Yao et al. 2003), then 2-3 of our objects may have significant contributions to the L_IR by dust-enshrouded AGNs.

Relationship of lipoprotein-associated phospholipase A2 and oxidized low density lipoprotein in carotid atherosclerosis

Plasma levels of lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) and oxidized low density lipoprotein (oxLDL) have been identified as risk factors for cardiovascular disease. Lp-PLA(2) is the sole enzyme responsible for the hydrolysis of oxidized phospholipids on LDL particles in atherosclerotic plaques. We have studied the relationship between Lp-PLA(2) and oxLDL in carotid endarterectomy (CEA) tissues and in matched plasmas. In extracts from CEA anatomical segments, the levels of oxLDL were significantly associated with the levels of Lp-PLA(2) protein (r = 0.497) and activity (r = 0.615). OxLDL and Lp-PLA(2) mass/activity were most abundant in the carotid bifurcation and internal segments where plaque was most abundant. In extracts from CEA atheroma, the levels of oxLDL and Lp-PLA(2) were significantly correlated (r = 0.634). In matched plasma and atheroma extracts, the levels of Lp-PLA(2) were negatively correlated (r = - 0.578). The ratio of Lp-PLA(2) to oxLDL was higher in atheromatous tissue (277:1) than in normal tissue (135:1) and plasma (13:1). Immunohistochemical experiments indicated that in plaques, oxLDL and Lp-PLA(2) existed in overlapping but distinctly different distribution. Fluorescence microscopy showed both oxLDL and Lp-PLA(2) epitopes on the same LDL particle in plasma but not in plaque. These results suggest that the relationship between Lp-PLA(2) and oxLDL in the atherosclerotic plaque is different from that in the plasma compartment.