Where and how much : density scenarios for the residential build-out of Gaoming, China

Thesis (S.M. and M.C.P.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, 2005.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references (p. 93-95).The author will use Gaoming District in the western part of China's Pearl River Delta (PRD) as an opportunity to examine the impact a range of residential densities along planned public transportation corridors can have on the rate and degree of agricultural land conversion in urbanizing areas. The author will use collected field data on the existing densities of old and new residential building construction in Gaoming, Gaoming District's 2004 Master Plan, projected population and economic growth figures from the Gaoming planning Department, and the parameters of land leasing and revenue generation in China as inputs in her analysis. The author will then present scenarios where a range of residential densities is created from variations in the degree of government planning, public transportation investment and land leasing methods. Moreover, the author will present instructions to build an economic model for planners to understand the land valuation process by which private developers bid for land. Lastly, the author will make recommendations to the planners and officials for how they can generate more revenue from land and work towards the sustainable build-out of Gaoming.by Karen Jia Ying Hu.S.M.and M.C.P

Hall effect and magnetoresistance in single crystals of NdFeAsO1−x_{1-x}Fx_{x}

Hall effect and magnetoresistance have been measured on single crystals of $NdFeAsO_{1-x}F_{x}$ with x = 0 ($T_c$ = 0 $$K) and x = 0.18 ($T_c$ = 50 $$K). For the undoped samples, strong Hall effect and magnetoresistance with strong temperature dependence were found below about 150 K. The magnetoresistance was found to be as large as 30% at 15 K at a magnetic field of 9 T. From the transport data we found that the transition near 155 K was accomplished in two steps: first one occurs at 155 K which may be associated with the structural transition, the second one takes place at about 140 K which may correspond to the spin-density wave like transition. In the superconducting sample with $T_c$ = 50 $$K, it is found that the Hall coefficient also reveals a strong temperature dependence with a negative sign. But the magnetoresistance becomes very weak and does not satisfy the Kohler's scaling law. These dilemmatic results (strong Hall effect and very weak magnetoresistance) prevent to understand the normal state electric conduction by a simple multi-band model by taking account the electron and hole pockets. Detailed analysis further indicates that the strong temperature dependence of $R_H$ cannot be easily understood with the simple multi-band model either. A picture concerning a suppression to the density of states at the Fermi energy in lowering temperature is more reasonable. A comparison between the Hall coefficient of the undoped sample and the superconducting sample suggests that the doping may remove the nesting condition for the formation of the SDW order, since both samples have very similar temperature dependence above 175 K.Comment: 8 pages, 9 figure

Multi-source thermal model describing multi-region structure of transverse momentum spectra of identified particles and parameter dynamics of system evolution in relativistic collisions

In this article, the multi-region structure of transverse momentum ($p_T$) spectra of identified particles produced in relativistic collisions is studied by the multi-component standard distribution (the Boltzmann, Fermi-Dirac, or Bose-Einstein distribution) in the framework of a multi-source thermal model. Results are interpreted in the framework of string model phenomenology in which the multi-region of $p_T$ spectra corresponds to the string hadronization in the cascade process of string breaking. The contributions of the string hadronizations from the first-, second-, and third-, i.e., last-generations of string breakings mainly form high-, intermediate-, and low-$p_T$ regions, respectively. From the high- to low-$p_T$ regions, the extracted volume parameter increases rapidly, and temperature and flow velocity parameters decrease gradually. The multi-region of $p_T$ spectra reflects the volume, temperature, and flow velocity dynamics of the system evolution. Due to the successful application of the multi-component standard distribution, this work reflects that the simple classical theory can still play a great role in the field of complex relativistic collisions.Comment: 15 pages, 7 figures. Indian Journal of Physics, accepte

Extracting Kinetic Freeze-out Properties in High Energy Collisions Using a Multi-source Thermal Model

We study the transverse momentum ($p_T$) spectra of neutral pions and identified charged hadrons produced in proton--proton ($pp$), deuteron--gold ($d$--Au), and gold--gold (Au--Au) collisions at the center of mass energy $\sqrt{s_{NN}}=200$ GeV. The study is made in the framework of a multi-source thermal model used in the partonic level. It is assumed that the contribution to the $p_T$-value of any hadron comes from two or three partons with an isotropic distribution of the azimuthal angle. The contribution of each parton to the $p_T$-value of a given hadron is assumed to obey any one of the standard (Maxwell-Boltzmann, Fermi-Dirac, and Bose-Einstein) distributions with the kinetic freeze-out temperature and average transverse flow velocity. The $p_T$-spectra of the final-state hadrons can be fitted by the superposition of two or three components. The results obtained from our Monte Carlo method are used to fit the experimental results of the PHENIX and STAR Collaborations. The results of present work serve as a suitable reference baseline for other experiments and simulation studies.Comment: 18 pages, 8 figure

Critical Fields and Anisotropy of NdO0.82F0.18FeAs Single Crystals

The newly discovered iron-based superconductors have stimulated enormous interests in the field of superconductivity. Since the new superconductor is a layered system, the anisotropy is a parameter with the first priority to know. Meanwhile any relevant message about the critical fields (upper critical field and irreversibility line) are essentially important. By using flux method, we have successfully grown the single crystals NdO0.82F0.18FeAs at ambient pressure. Resistive measurements reveal a surprising discovery that the anisotropy \Gamma = (mc/mab)^{1/2} is below 5, which is much smaller than the theoretically calculated results. The data measured up to 400 K show a continuing curved feature which prevents a conjectured linear behavior for an unconventional metal. The upper critical fields determined based on the Werthamer-Helfand-Hohenberg formula are H_{c2}^{H||ab}(T=0 K) = 304 T and H_{c2}^{H||c}(T=0 K)=62-70 T, indicating a very encouraging application of the new superconductors.Comment: 12 pages, 4 figures, Submitted on 26 May, 200

Characterization of long-chain acyl-CoA synthetases which stimulate secretion of fatty acids in green algae Chlamydomonas reinhardtii

Additional file 1. Complete list of primers used in this study

PI3K-GLUT4 Signal Pathway Associated with Effects of EX-B3 Electroacupuncture on Hyperglycemia and Insulin Resistance of T2DM Rats

Objectives. To explore electroacupuncture’s (EA’s) effects on fasting blood glucose (FBG) and insulin resistance of type 2 diabetic mellitus (T2DM) model rats and give a possible explanation for the effects. Method. It takes high fat diet and intraperitoneal injection of streptozotocin (STZ, 30 mg/kg) for model preparation. Model rats were randomly divided into T2DM Model group, EA weiwanxiashu (EX-B3) group, and sham EA group (n=12/group). EA (2 Hz continuous wave, 2 mA, 20 min/day, 6 days/week, 4 weeks) was applied as intervention. FBG, area under curve (AUC) of oral glucose tolerance test (OGTT), insulin resistance index (HOMA-IR), pancreatic B cell function index (HOMA-B), skeletal muscle phosphorylated phosphatidylinositol-3-kinase (PI3K), glucose transporter 4 (GLUT4), and membrane GLUT4 protein expression were measured. Results. EA weiwanxiashu (EX-B3) can greatly upregulate model rat’s significantly reduced skeletal muscle PI3K (Y607) and membrane GLUT4 protein expression (P<0.01), effectively reducing model rats’ FBG and AUC of OGTT (P<0.01). The effects are far superior to sham EA group. Conclusion. EA weiwanxiashu (EX-B3) can upregulate skeletal muscle phosphorylated PI3K protein expression, to stimulate membrane translocation of GLUT4 and thereby increase skeletal muscle glucose intake to treat T2DM

Topological Atomic Spinwave Lattices by Dissipative Couplings

Recent experimental advance in creating dissipative couplings provides a new route for engineering exotic lattice systems and exploring topological dissipation. Using the spatial lattice of atomic spinwaves in a vacuum vapor cell, where purely dissipative couplings arise from diffusion of atoms, we experimentally realize a dissipative version of the Su-Schrieffer-Heeger (SSH) model. We construct the dissipation spectra of the topological or trivial lattices via electromagnetically-induced-transparency (EIT) spectroscopy. The topological dissipation spectrum is found to exhibit edge modes at dissipation rates within a dissipative gap, decoupled from the bulk. We also validate chiral symmetry of the dissipative SSH couplings. This work paves the way for realizing topology-enabled quantum correlations and non-Hermitian topological quantum optics via dissipative couplings.Comment: 5 pages, 4 figure