Calculated Capture Rates Research Articles

Quantifying capture and ingestion of live feeds across three coral species

Nutrient acquisition through heterotrophy is critical for the health of reef-building corals. The optimization of exogenous nutrition protocols to support a diversity of aquaculture corals requires improved techniques to assess feeding rates. Here, we compared the feeding rates of three coral species (Acropora millepora, Pocillopora acuta and Galaxea fascicularis) fed Artemia salina through capture rate (indirect) and dissection (direct) approaches, with direct detection and enumeration within dissected polyps facilitated by fluorescent microbeads ingested by the Artemia. When A. millepora was provided Artemia at 3 individuals ml−1 for one hour, the calculated capture rates (0.7 ind. polyp−1 h−1) overestimated prey ingested compared to prey detected directly within polyps (0.2 ind. polyp−1 h−1), and ingestion varied significantly between genotypes. In contrast, for P. acuta, capture rate calculations (1 ind. polyp−1 h−1) underestimated prey detected within polyps (3.5 ind. polyp−1 h−1) and ingestion did not vary between genotypes. For G. fascicularis, the feeding rates were similar as calculated by both capture rates (59 ind. polyp−1 h−1) and by polyp dissections (75 ind. polyp−1 h−1). Results from this study provide valuable insights into coral feeding rates of different coral species that can improve prey enrichment and feeding strategies for nutritional supplementation of corals in captivity.

Elementary Reactions Leading to Perfluoroalkyl Substance Degradation in an Ar+/e- Plasma.

The reactivities of three perfluoroalkyl carboxylic acids (PFCAs) (perfluoropropanoic acid (C2F5COOH, PFPA), perfluorobutanoic acid (C3F7COOH, PFBA), and perfluorooctanoic acid (C7F15COOH, PFOA)) in a thermal, weakly ionized, argon/electron plasma were investigated from 300 to 600 K using a Langmuir probe-flowing afterglow apparatus. The results are supported by density functional theory calculations of the energetics of PFCA, CnF2n+1COOH, from n = 1 to 7. PFPA and PFBA attach electrons at a substantial fraction of the calculated capture rate; PFOA likely attaches electrons with similarly high efficiency, but the low vapor pressure of PFOA resulted in only qualitative results. All three compounds attach electrons dissociatively via HF elimination. The "acidity channel" (i.e., formation of H + CnF2n+1COO-), calculated to be slightly endothermic, is never observed even at higher temperatures where this channel would be energetically allowed. Attachment to perfluorooctanesulfonic acid (n-C8F17SO3H) is rapid, yielding the conjugate base n-C8F17SO3- as proton transfer to the electron is exothermic. At temperatures near 450 K (PFOA), 550 K (PFBA), or 600 K (PFPA), the parent neutrals thermally decompose as evidenced by abrupt changes in rate constants and branching ratios. PFPA and PFBA react with Ar+ close to the calculated capture rate, and PFOA likely does as well. The reaction mechanism starts via charge transfer, which can then lead to a range of product ions. Reactions with Ar+ yield fluorocarbon radicals, clarifying and supporting a previously proposed mechanism of PFCA degradation in an argon plasma.

Statistical quantum mechanical approach to diatom-diatom capture dynamics and application to ultracold KRb + KRb reaction.

A general and rigorous quantum method is proposed for studying capture dynamics between two diatomic molecules in full dimensionality. By solving the time-independent Schrödinger equation with proper boundary conditions, this method is ideally suited for studying quantum dynamics of cold and ultracold reactions. To illustrate its applicability, the capture dynamics between ultracold KRb molecules is characterized in full six dimensions for the first time using a first-principles based long-range interaction potential. The calculated capture rates for collisions involving distinguishable and indistinguishable 40K87Rb molecules are in good agreement with the experiment and exhibit clear Wigner threshold behaviors. Predictions for ultracold collisions between internally excited 40K87Rb suggest minor changes in the loss rate, consistent with experimental observations in similar systems.

Comprehensive capture of cutaneous melanoma by the Ontario Cancer Registry: validation study using community pathology reports.

Melanoma is often managed outside hospital settings, creating the potential for underreporting to cancer registries. To our knowledge, completeness of melanoma capture in cancer registries has not been assessed using external data sources since the 1980s. We evaluated the melanoma capture rate from 1993 to 2009 in a provincial cancer registry. We identified all melanoma diagnoses in pathology reports from a major community laboratory in Ontario, Canada. Pathologically confirmed diagnoses were linked to Ontario Cancer Registry (OCR) records using health insurance numbers. We calculated capture rates as the proportion of patients with melanoma confirmed by a pathology report, with a corresponding melanoma diagnosis in OCR. OCR captured 3,798 of 4,275 (88.8, 95 % confidence interval: 87.9, 89.8 %) invasive melanoma diagnoses over the 17-year period. Annual capture rates of 94 % or higher were found for over half the study period. Among all 29,133 melanoma diagnoses in OCR, 27.6 % were registered based on a pathology report alone, compared with 3.4 % for non-cutaneous malignancies. This suggests that comprehensive capture of melanoma cases by a provincial cancer registry is achievable using source data from community laboratories. There is a need for ongoing validation to ensure data remain accurate and complete to reliably inform clinical care, research, and policy.

Abstract 380: Capture of EpCAM-negative circulating tumor cells (CTCs) with a “Universal CTC-Chip”

Abstract Background: Circulating tumor cell (CTC) can be a potentially useful clinical marker in early diagnosis and monitoring therapeutic effects for patients with malignant tumors. Our previous study showed that CTC detected by an EpCAM (epithelial cell adhesion molecule) based immuno-magnetic separation system “CellSearch” was useful in the diagnosis of malignant pleural mesothelioma (MPM), and also useful in the prognosis of epithelioid type MPM (Yoneda K, et al. Ann Surg Oncol. 2013). However, EpCAM-negative tumor cells cannot be principally captured with the system. Therefore, we have developed EpCAM-independent “Universal CTC-Chip System”, and assessed its capture capability. Methods: PC-9 (lung cancer cell line) was employed as EpCAM-positive cells, ACC-MESO-1 and ACC-MESO-4 (mesothelioma cell lines) were employed as EpCAM-negative cells. The expression of cell surface antigen was confirmed by flow cytometry. A microfluidic devices made of resin was coated in two steps with bridging antibody and capture antibody. It is possible to use any antibody to capture. In this study, we use anti-EpCAM antibody, anti-podoplain antibody, anti-mesothelin antibody, and isotype control. First, we verified capture capability of this system using samples which were spiked tumor cells labeled with CFSE in PBS containing 5% BSA. Then, we measured in the same manner by adding the cells to the blood of healthy donor, and calculated capture rate. Results: The expression analysis of cell surface antigens, PC-9 was EpCAM-positive, podoplanin, mesothelin were negative. On the other hand, MESO-1, 4 was EpCAM negative, podoplanin, mesothelin were positive. The capture efficiency in PBS containing 5% BSA with each cell using anti-EpCAM antibody, anti-podoplanin antibody and anti-mesothelin were PC-9: 101.1% / 2.3% / 2.9%, MESO-1: 3.5% / 52.7% / 4.3%, MESO-4: 3.0% / 78.3% / 5.4%, respectively. In the study of blood, each of the capture rate using anti-EpCAM antibody and anti-podoplanin antibody were PC-9: 88.0/ 6.9%, MESO-1: 4.0%/ 12.7%, MESO-4: 2.2%/ 38.4%, respectively. Conclusions: The capture efficiency using this device depends on the expression intensity of cell surface antigens. In experiments with PBS samples, it was possible to capture targeting specific cell surface antigen. Mesothelioma cells in the blood ware captured with combination of this CTC-Chip system and anti-podoplanin antibody. Citation Format: Kazue Yoneda, Yasuhiro Chikaishi, Eri Kawashima, Tomoko So, Hidetaka Uramoto, Takashi Ohnaga, Fumihiro Tanaka. Capture of EpCAM-negative circulating tumor cells (CTCs) with a “Universal CTC-Chip”. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 380. doi:10.1158/1538-7445.AM2015-380

Fine-grid calculations for stellar electron and positron capture rates on Fe isotopes

The acquisition of precise and reliable nuclear data is a prerequisite to success for stellar evolution and nucleosynthesis studies. Core-collapse simulators find it challenging to generate an explosion from the collapse of the core of massive stars. It is believed that a better understanding of the microphysics of core-collapse can lead to successful results. The weak interaction processes are able to trigger the collapse and control the lepton-to-baryon ratio (Y e ) of the corematerial. It is suggested that the temporal variation of Y e within the core of a massive star has a pivotal role to play in the stellar evolution and a fine-tuning of this parameter at various stages of presupernova evolution is the key to generate an explosion. During the presupernova evolution of massive stars, isotopes of iron, mainly 54–56Fe, are considered to be key players in controlling Y e ratio via electron capture on these nuclides. Recently an improved microscopic calculation of weak-interaction-mediated rates for iron isotopes was introduced using the proton-neutron quasiparticle random-phase-approximation (pn-QRPA) theory. The pn-QRPA theory allows a microscopic state-by-state calculation of stellar capture rates which greatly increases the reliability of calculated rates. The results were suggestive of some fine-tuning of the Y e ratio during various phases of stellar evolution. Here we present for the first time the fine-grid calculation of the electron and positron capture rates on 54–56Fe. The sensitivity of the pn-QRPA calculated capture rates to the deformation parameter is also studied in this work. Core-collapse simulators may find this calculation suitable for interpolation purposes and for necessary incorporation in the stellar evolution codes.

Shell model study on the astrophysical neutron capture of 8Li

The astrophysical important neutron capture of 8Li is investigated by combining the shell model and potential model. Three effective interactions, SFO, PSDMK2 and PSDWBP are used to calculate the spectroscopic factors and reaction widths. For the resonant capture from 8Li to the first continuum state of 9Li , the three effective interactions give similar neutron partial widths, and they are well compared with the experimental results. However, the calculated photon widths are over 5 times less than the previous estimate. This will make the substantial difference that, at high temperature, the direct capture mechanism still dominates. The calculated capture rates generally agree well with the experimental data. The uncertainty of calculated cross-sections and capture rates mainly results from the different prediction of spectroscopic factors for the three effective interactions. The total neutron capture rates in our calculations are less than 4300 cm3 mole−1 s−1 for T9 < 5 which confirms that the main reaction flow will proceed through the reaction 8Li (α, n) 11B in the stellar environments.

Abstract 1145: Analysis of circulating tumor cells from castrate resistant prostate cancer patients captured via a microfluidic device using the prostate specific membrane antigen antibody

Abstract Prostate cancer (PC) is the most common type of cancer in males and the second leading cause of male cancer deaths in the United States. Circulating tumor cells (CTCs) are commonly found in the blood of patients suffering from mestatic disease and the capture of these cells is important in the study of disease progression. Existing devices use the EpCAM antibody which can capture circulating epithelial cancer cells, but also leads to a large number of leukocyte contamination. We have developed a microfluidic chip functionalized with an antibody to the prostate-specific membrane antigen (PSMA), which captures prostate CTCs with high purity and efficiency. This chip is designed with a staggered obstacle array that maximizes the CTC-wall interactions while minimizing the interactions with the other cells in the blood. PSMA-positive or -negative PC cells were spiked into blood from healthy donors, and we calculated capture rates to be ∼80%. Next, blood samples from patients (n = 20) with castrate resistant prostate cancer (CRPC) were run through the device and CTCs were captured and enumerated. CTCs were found in 90% of samples tested with the number captured averaging 27 ± 4 cells per mL of blood with a capture purity of 62 ± 2%. We plan to use this device to elucidate the molecular basis of CRPC clinical response to taxane treatment, which is the only class of chemotherapy drugs shown to improve survival in this type of PC. Previous data from our laboratory has shown that taxane treatment of PC cells inhibits the ligand-induced androgen receptor (AR) nuclear accumulation and transcriptional activation of androgen response element (ARE) containing genes including the prostate-specific antigen (PSA). These results implicate microtubules (MTs) in AR trafficking and suggest that the clinical activity of taxanes in CRPC may be mediated in part by the drugs’ ability to stabilize MTs and inhibit AR transcriptional activity. We plan to capture CTCs using the PSMA-specific microfluidic device from CRPC patients receiving taxane treatment and analyze them for AR subcellular distribution and correlate clinical response to taxane treatment. Our microfluidic device is a novel, specific, and improved technology to capture prostate CTCs that will allow us to better define the molecular basis of taxane treatment in CRPC patients. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1145.

Relativistic quasiparticle random-phase approximation calculation of total muon capture rates

The relativistic proton-neutron quasiparticle random phase approximation ($\mathit{pn}$-RQRPA) is applied in the calculation of total muon capture rates on a large set of nuclei from $^{12}\mathrm{C}$ to $^{244}\mathrm{Pu}$, for which experimental values are available. The microscopic theoretical framework is based on the relativistic Hartree-Bogoliubov (RHB) model for the nuclear ground state, and transitions to excited states are calculated using the $\mathit{pn}$-RQRPA. The calculation is fully consistent, i.e., the same interactions are used both in the RHB equations that determine the quasiparticle basis, and in the matrix equations of the $\mathit{pn}$-RQRPA. The calculated capture rates are sensitive to the in-medium quenching of the axial-vector coupling constant. By reducing this constant from its free-nucleon value ${g}_{A}=1.262$ by 10% for all multipole transitions, the calculation reproduces the experimental muon capture rates to better than 10% accuracy.

Expanded calculations of proton–neutron quasi-particle random phase approximation (pn-QRPA) electron capture rates on 55Co for presupernova and supernova physics

Because of its abundance and its relatively high capture rates, 55Co is one of the key nuclide that can control the dynamics of core collapse of a massive star. Previously we introduced our microscopic calculations of capture rates on 55Co using the proton–neutron quasi-particle random phase approximation (pn-QRPA) theory. Here, we present for the first time an expanded calculation of the electron capture rates on 55Co on an extensive temperature-density scale. This type of scale is appropriate for interpolation purposes and of greater utility for simulation codes.PACS Nos.: 26.50.+x, 21.60.Jz, 23.40.–s, 27.40.+z

Neutrino energy loss rates and positron capture rates onCo55for presupernova and supernova physics

Proton-neutron quasi-particle random phase approximation (pn-QRPA) theory has recently being used for calculation of stellar weak interaction rates of $fp$-shell nuclide with success. Neutrino losses from proto-neutron stars play a pivotal role to decide if these stars would be crushed into black holes or explode as supernovae. The product of abundance and positron capture rates on $^{55}$Co is substantial and as such can play a role in fine tuning of input parameters of simulation codes specially in the presupernova evolution. Recently we introduced our calculation of capture rates on $^{55}$Co, in a luxurious model space of $7 \hbar \omega$, employing the pn-QRPA theory with a separable interaction. Simulators, however, may require these rates on a fine scale. Here we present for the first time an expanded calculation of the neutrino energy loss rates and positron capture rates on $^{55}$Co on an extensive temperature-density scale. These type of scale is appropriate for interpolation purposes and of greater utility for simulation codes. The pn-QRPA calculated neutrino energy loss rates are enhanced roughly up to two orders of magnitude compared with the large-scale shell model calculations and favor a lower entropy for the core of massive stars.

Shell model study ofCa40muon capture and the(0+,0keV)→(0−,2626keV) axial charge transition

We report results from shell-model studies of muon capture on $^{40}\mathrm{Ca}$ to low-lying levels of $^{40}\mathrm{K}$. We discuss the comparison among calculated capture rates, measured capture rates, and analogous transitions in ($e,{e}^{'}$) scattering in terms of the particle-hole structure of the $^{40}\mathrm{Ca}$-$^{40}\mathrm{K}$ nuclei. We highlight the $^{40}\mathrm{Ca}$$({0}^{+},0)\ensuremath{\rightarrow}$$^{40}\mathrm{K}$$({0}^{\ensuremath{-}},2626)$ axial charge transition and its sensitivity to the induced pseudoscalar coupling ${g}_{p}$ of the proton's weak interaction. In addition, we address the hindrance of unique first-forbidden transitions due to particle-hole interactions and the emergence of allowed Gamow-Teller transitions due to ground-state correlations. Last, we examine the longitudinal alignment of $^{40}\mathrm{K}$ recoils following muon capture and discuss this possibility for independently determining the induced coupling ${g}_{p}$.

A Theoretical Study of the Dynamics of the S + c-C3H Reaction

A theoretical study of the dynamics of the S + c-C3H reaction was carried out, following a theoretical approach in which the reaction is decomposed in two steps: the collision process and the evolution of the reaction intermediate formed in the reactive collisions. In both steps, classical dynamical methods were employed. For the collision step, we used an analytical potential energy surface in conjunction with a Hamiltonian based on the adiabatic capture centrifugal sudden approximation, whereas for the second step, we computed direct trajectories with a hybrid analytical and MNDO-type potential energy surface with specific reaction parameters. We calculated capture rate coefficients for the temperature interval [60−600 K] as well as branching ratios for T = 100 and 300 K. Our results suggest that the overall reaction rate is quite high but also that production of SC3 + H may have a branching ratio of about 50%, SC + C2H being the other main product. The results were compared to those of a similar study...

An experimental and theoretical study of the product distribution of the reaction CH2 (X 3B1) + NO.

Measurements of the product branching ratios of the reaction CH2 (X 3B1) + NO (1) are presented together with calculations of the thermal rate constant and branching ratios using unimolecular rate theory. The reaction was investigated experimentally at room temperature using FTIR spectroscopy. The yields of the main products HCNO and HCN were found to be gamma HCNO = 0.89 +/- 0.06, gamma HCN = 0.11 +/- 0.06. Other minor products could be rationalized by numerical simulations of the reaction system taking into account possible consecutive reactions. The potential energy surface for the reaction was characterized by quantum chemical calculations using ab initio and density functional methods. The proposed reaction pathways connecting reactants to products were explored by multi-channel unimolecular rate theory calculations to determine the CH2 (X) + NO capture rate constant and the rate constants for the different product channels as a function of temperature. The calculated capture rate constant of k = 2.3 x 10(13) cm3 mol-1 s-1 is in good agreement with experimental values at room temperature. Collisional stabilization of the initial H2CNO recombination complex was predicted to be negligible up to pressures of > 1 bar. For ambient pressures and temperatures up to 2000 K, HCNO + H were calculated as the dominating products, with gamma HCNO approximately 0.94 in agreement with the experiments. The channel to HCN + OH was calculated with 0.015 < or = gamma HCN < or = 0.05, only slightly below the experimental value.

Tidal disruption rates of stars in observed galaxies

We derive the rates of capture, Ndot, of main sequence turn off stars by the central massive black hole in a sample of galaxies from Magorrian et al. 1998. The disruption rates are smaller than previously believed with Ndot ~ 10^-4 - 10^-7 per galaxy. A correlation between Ndot and black hole mass, M, is exploited to estimate the rate of tidal disruptions in the local universe. Assuming that all or most galaxies have massive black holes in their nuclei, this rate should be dominated by sub-Lstar galaxies. The rate of tidal disruptions could be high enough to be detected in supernova (or similar) monitoring campaigns---we estimate the rate of tidal disruptions to be 0.01 - 0.1 times the supernova rate. We have also estimated the rates of disruption of red giants, which may be significant (Ndot ~> 10^-4 y^-1 per galaxy) for M ~> 10^8 Msun, but are likely to be harder to observe---only of order 10^-4 times the supernova rate in the local universe. In calculating capture rates, we advise caution when applying scaling formulae by other authors, which are not applicable in the physical regime spanned by the galaxies considered here.

Effective capture rates of carriers in amorphous hydrogenated silicon

The effective capture rates of electrons and holes by the defects of undoped a-Si:H are measured using a technique based on the optical bias dependence of the modulated photocurrent. The evolution of the phase shift and modulated photocurrent spectra with the optical bias intensity is used to study the capture coefficient of the defects at different trap depths in the energy gap. The modulated photocurrent spectra are recorded using uniformly, or strongly absorbed light in order to obtain information about the trapping and recombination processes in the surface, the interface, and the bulk of the films. The calculated capture rates of carriers are studied in a series of a-Si:H films and information about the defect structure is obtained. It is found that the effective capture rates of the carriers by the defects are not constant in the studied films and may vary by up to two orders of magnitude from sample to sample. Finally, the importance of the atomic environment and the local strains of the defects of a-Si:H for the capture process of the carriers is discussed.

Collision-theory treatment of the reactions of methyl ion(1+) with hydrogen, deuterium, nitrogen, oxygen, nitric oxide, carbon monoxide, carbon dioxide, hydrogen cyanide, and ammonia

Rate constants have been calculated for bimolecular and, where appropriate, termolecular reactions in the presence of helium, neon, and argon bath gases, over the temperature range from 10 to 400 K. The contribution of the ion's rotational energy to the centrifugal barrier is included in all cases except the bimolecular reactions of CH 3 + with H 2 , D 2 , and O 2 . For the reaction of CH 3 + with NO, the calculated capture rate is identical with the measured charge-transfer rate at 300 K. For collisions of CH 3 R + complex ions with helium, inclusion of ion rotations causes the rate to be less than the Langevin rate by up to a factor of 3 at room temperature

Collision-theory calculations for some quadrupole-quadrupole reactions of O( 1D)

Langevin-type capture rate constants have been obtained for collisions of O( 1D) with CO 2, H 2, N 2 and O 2, using approximate quasiclassical trajectory calculations with a combined quadrupole-quadrupole + London + Morse potential, over the temperature range 10–600 K. The calculated capture rates depend about equally on the quadrupole-quadrupole and London potentials and are independent of the Morse potential. Rate constants are obtained in good agreement with listed experimental values at 300 K when the calculated capture rates are multiplied by a factor of 0.2 for electronic degeneracy and by a factor of 1.0, 0.545 or 0.455 for orientation. These orientation factors derive from the angular factors of the quadrupole-quadrupole potential. For the reactions with O 2 and CO 2 the orientation factor is 1.0 (no preferred orientation), for reaction with H 2 it is 0.545 (end-on collisions favoured), and for reaction with N 2 it is 0.455 (perpendicular collisions favoured).

Dynamics of bimolecular association reactions

An approximate semiclassical trajectory method has been used to calculate capture rates for ion–dipole and dipole–dipole reactions at temperatures between 10 and 400 K. Agreement with experimental data and with other theories is excellent for the reactions of H+3 with HCl and HCN and fair for the reaction ClO with NO. A formal expression for the rate constant for intramolecular vibrational relaxation (IVR) has been derived, and an approximate form of this expression has been used, together with trajectory calculations of capture rates, to model the formation of metastable complexes in the reactions of NH+4 with NH3 and of NH with NO2 and NO. The results suggest that the rate of stabilization of the initial collision complex by IVR may have a significant influence on both the absolute value of the overall rate constant and its temperature dependence.

Calculation of capture rates of solar and galactic neutrinos by69Ga and71Ga

Calculations of the neutrino-capture cross sections for69,71Ga based on a microscopic treatment of the Gamow-Teller matrix elements are presented. A strong enhancement of the cross-section for high-energetic neutrinos is found compared to previous phenomenological estimates. As a consequence the present assumptions on the signal from8B neutrinos in71Ga have to be revised. A rather large solar model dependent background of8B neutrinos has to be expected in a gallium solarneutrino experiment together with the pp signal. This will complicate the interpretation of such an experiment particularly in the case of neutrino oscillations with not maximum mixing angle. The calculations yield a larger sensitivity of the gallium detector than assumed previously for galactic neutrinos.