The Relative Role of Land in Climate Policy

Replaced with revised version of paper 06/26/09.Climate policy, land use related emissions, carbon forest sequestration, CGE, Environmental Economics and Policy,

Hard Rescattering in QCD and High Energy Two-Body Photodisintegration of the Deuteron

Photon absorption by a quark in one nucleon followed by its high momentum transfer interaction with a quark in the other may produce two nucleons with high relative momentum. We sum the relevant quark rescattering diagrams, to show that the scattering amplitude depends on a convolution between the large angle $pn$ scattering amplitude, the hard photon-quark interaction vertex and the low-momentum deuteron wave function. The computed cross sections are in reasonable agreement with the data.Comment: Four pages Latex, uses espcrc1.sty. Presented at 15th International Conference on Particle and Nuclei (PANIC 99), Uppsala, Sweden, 10-16 Jun 199

Quantifying the Effects of Hyperthermal Atomic Oxygen and Thermal Fatigue Environments on Carbon Nanotube Sheets for Space-Based Applications

The effects of atomic oxygen and thermal fatigue on two different types of carbon nanotube sheets were studied. One set was treated with nitric acid, while the other set was left untreated. Monotonic tensile tests were performed before and after exposure to determine the effects of either exposure type on the sheets’ mechanical properties. Electrical conductivity and electromagnetic interference measurements were recorded to determine the effects of AO-exposure and thermal cycling on the sheets’ electrical properties. Neither exposure type affected the sheets’ specific strengths. Both exposure types increased the sheets’ specific stiffnesses and decreased the sheets’ strains at failure. The electrical conductivity of both sheets decreased due to the different exposure types, while the EMI shielding effectiveness was unaffected. Scanning electron microscopy was used to observe any changes in the sheets’ surface morphologies, while energy-dispersive X-ray spectroscopy was used to determine the effects of AO on the sheets’ chemical makeup

Hard Break-Up of Two-Nucleons from the 3He Nucleus

We investigate a large angle photodisintegration of two nucleons from the $^3$He nucleus within the framework of the hard rescattering model (HRM). In the HRM a quark of one nucleon knocked out by an incoming photon rescatters with a quark of the other nucleon leading to the production of two nucleons with large relative momentum. Assuming the dominance of the quark-interchange mechanism in a hard NN scattering, the HRM allows to express the amplitude of a two-nucleon break-up reaction through the convolution of photon-quark scattering, $NN$ hard scattering amplitude and nuclear spectral function. The photon-quark scattering amplitude can be explicitly calculated in the high energy regime, whereas for $NN$ scattering one uses the fit of the available experimental data. The HRM predicts several specific features for the hard breakup reaction. First, the cross section will approximately scale as $s^{-11}$. Secondly, the $s^{11}$ weighted cross section will have the shape of energy dependence similar to that of $s^{10}$ weighted $NN$ elastic scattering cross section. Also one predicts an enhancement of the $pp$ breakup relative to the $pn$ breakup cross section as compared to the results from low energy kinematics. Another result is the prediction of different spectator momentum dependencies of $pp$ and $pn$ breakup cross sections. This is due to the fact that same-helicity $pp$-component is strongly suppressed in the ground state wave function of $^3$He. Because of this suppression the HRM predicts significantly different asymmetries for the cross section of polarization transfer $NN$ breakup reactions for circularly polarized photons. For the $pp$ breakup this asymmetry is predicted to be zero while for the $pn$ it is close to ${2\over 3}$.Comment: 33 pages and 8 figures, version published in Physical Review

Spectrally-resolved Imaging of the Transverse Modes in Multimode VCSELs

Vertical-cavity surface-emitting lasers (VCSELs) enable a range of applications such as data transmission, trace sensing, atomic clocks, and optical mice. For many of these applications, the output power and beam quality are both critical (i.e. high output power with good beam quality is desired). Multi-mode VCSELs offer much higher power than single-mode devices, but this comes at the expense of lower beam quality. Directly observing the resolved mode structure of multi-mode VCSELs would enable engineers to better understand the underlying physics and help them to develop multi-mode devices with improved beam quality. In this work, a low-cost, high-resolution (\u3c3 \u3epm) Echelle grating spectrometer system is used to map the two-dimensional VCSEL near-field emission profile. The system spectrally disperses the VCSEL beam and images it with high magnification onto a CMOS camera. The narrow spectral content of each LP mode allows direct observation of the modal content of the VCSEL

Male Partners Involvement in Spousal Contraceptive Use: A Perspective of a Contemporary African Setting

Background: Contraceptive use by women is one of the tools used for promoting family health and slowing population growth. Evidence has suggested that contraceptive use in Nigeria is below acceptable levels in spite of the fact that family planning services are readily available, accessible and affordable. The involvement and participation of males in spousal contraceptive use is seen as the driver to achieving better reproductive outcomes. Hence, this study aimed to determine the level of male involvement in spousal contraceptive use so as to provide evidence based and people oriented information on the available male partner support system for contraceptive use and factors influence it.Methodology: This was a cross sectional study conducted among 80 male partners between April and May, 2017 using quantitative method of data collection and SPSS version 20 was used for data analysis.nbsp Crude and adjusted odds ratios as well asnbsp 95% confidence interval were used in this study with a p-value of le 0.05 considered statistically significant.Results: The mean age of the respondents in the study was 40.0 plusmn 10 years with only 13 (16.3%) of the respondents adjudged as being involved in their spousal contraceptive use. Currently use of male contraceptive method was found to significantly influence involvement in spousal contraceptive use (AOR = 7.1 95% CI = 2.1092 ndash 10.5818 P = 0.015). Conclusion: This study has demonstrated a low level of male involvement in spousal contraceptive use hence, relevant male educational intervention on contraception is required

QCD Rescattering and High Energy Two-Body Photodisintegration of the Deuteron

Photon absorption by a quark in one nucleon followed by its high momentum transfer interaction with a quark in the other may produce two final-state nucleons with high relative momentum. We sum the relevant quark rescattering diagrams, to show that the scattering amplitude depends on a convolution between the large angle $pn$ scattering amplitude, the hard photon-quark interaction vertex and the low-momentum deuteron wave function. The computed absolute values of the cross section are in reasonable agreement with the data.Comment: 4 pages, revised version to be published in Phys. Rev. Let

Recent observation of short range nucleon correlations in nuclei and their implications for the structure of nuclei and neutron stars

Novel processes probing the decay of nucleus after removal of a nucleon with momentum larger than Fermi momentum by hard probes finally proved unambiguously the evidence for long sought presence of short-range correlations (SRCs) in nuclei. In combination with the analysis of large $Q^2$, A(e,e')X processes at $x>1$ they allow us to conclude that (i) practically all nucleons with momenta $\ge$ 300 MeV/c belong to SRCs, consisting mostly of two nucleons, ii) probability of such SRCs in medium and heavy nuclei is $\sim 25$, iii) a fast removal of such nucleon practically always leads to emission of correlated nucleon with approximately opposite momentum, iv) proton removal from two-nucleon SRCs in 90% of cases is accompanied by a removal of a neutron and only in 10% by a removal of another proton. We explain that observed absolute probabilities and the isospin structure of two nucleon SRCs confirm the important role that tensor forces play in internucleon interactions. We find also that the presence of SRCs requires modifications of the Landau Fermi liquid approach to highly asymmetric nuclear matter and leads to a significantly faster cooling of cold neutron stars with neutrino cooling operational even for $N_p/N_n \le 0.1$. The effect is even stronger for the hyperon stars. Theoretical challenges raised by the discovered dominance of nucleon degrees of freedom in SRCs and important role of the spontaneously broken chiral symmetry in quantum chromodynamics (QCD) in resolving them are considered. We also outline directions for future theoretical and experimental studies of the physics relevant for SRCs.Comment: 74 pages. Review article, updated version to be published in International Journal of Modern Physics

Selected Topics in High Energy Semi-Exclusive Electro-Nuclear Reactions

We review the present status of the theory of high energy reactions with semi-exclusive nucleon electro-production from nuclear targets. We demonstrate how the increase of transferred energies in these reactions opens a complete new window in studying the microscopic nuclear structure at small distances. The simplifications in theoretical descriptions associated with the increase of the energies are discussed. The theoretical framework for calculation of high energy nuclear reactions based on the effective Feynman diagram rules is described in details. The result of this approach is the generalized eikonal approximation (GEA), which is reduced to Glauber approximation when nucleon recoil is neglected. The method of GEA is demonstrated in the calculation of high energy electro-disintegration of the deuteron and A=3 targets. Subsequently we generalize the obtained formulae for A>3 nuclei. The relation of GEA to the Glauber theory is analyzed. Then based on the GEA framework we discuss some of the phenomena which can be studied in exclusive reactions, these are: nuclear transparency and short-range correlations in nuclei. We illustrate how light-cone dynamics of high-energy scattering emerge naturally in high energy electro-nuclear reactions.Comment: LaTex file with 51 pages and 23 eps figure