The Measure of Poverty: A Boston Indicators Project Special Report

Examines Boston's poverty rate by race/ethnicity, family structure, education, and geography; income inequality; demand for safety-net programs; and how the high cost of living and budget cuts affect vulnerable households and those below the poverty line

Does Science Promote Women? Evidence from Academia 1973-2001

Many studies have shown that women are under-represented in tenured ranks in the sciences. We evaluate whether gender differences in the likelihood of obtaining a tenure track job, promotion to tenure, and promotion to full professor explain these facts using the 1973-2001 Survey of Doctorate Recipients. We find that women are less likely to take tenure track positions in science, but the gender gap is entirely explained by fertility decisions. We find that in science overall, there is no gender difference in promotion to tenure or full professor after controlling for demographic, family, employer and productivity covariates and that in many cases, there is no gender difference in promotion to tenure or full professor even without controlling for covariates. However, family characteristics have different impacts on women's and men's promotion probabilities. Single women do better at each stage than single men, although this might be due to selection. Children make it less likely that women in science will advance up the academic job ladder beyond their early post-doctorate years, while both marriage and children increase men's likelihood of advancing.

City of Ideas: Reinventing Boston's Innovation Economy: The Boston Indicators Report 2012

Analyzes indicators of the city's economic, social, and technological progress; potential for creating innovative solutions to global and national challenges; and complexities, disparities, and weaknesses in the indicators and innovation economy paradigm

Matrix product states approach to the Heisenberg ferrimagnetic spin chains

We propose a new version of the matrix product (MP) states approach to the description of quantum spin chains, which allows one to construct MP states with certain total spin and its z-projection. We show that previously known MP wavefunctions for integer-spin antiferromagnetic chains and ladders correspond to some particular cases of our general ansatz. Our method allows to describe systems with spontaneously broken rotational symmetry, like quantum ferrimagnetic chains whose ground state has nonzero total spin. We apply this approach to describe the ground state properties of the isotropic ferrimagnetic Heisenberg chain with alternating spins 1 and 1/2 and compare our variational results with the high-precision numerical data obtained by means of the quantum Monte Carlo (QMC) method. For both the ground state energy and the correlation functions we obtain very good agreement between the variational results and the QMC data.Comment: 4 pages, RevTeX, uses psfig.sty, submitted to Phys. Rev.

A DMRG Study of Low-Energy Excitations and Low-Temperature Properties of Alternating Spin Systems

We use the density matrix renormalization group (DMRG) method to study the ground and low-lying excited states of three kinds of uniform and dimerized alternating spin chains. The DMRG procedure is also employed to obtain low-temperature thermodynamic properties of these systems. We consider a 2N site system with spins $s_1$ and $s_2$ alternating from site to site and interacting via a Heisenberg antiferromagnetic exchange. The three systems studied correspond to $(s_1 ,s_2 )$ being equal to $(1,1/2),(3/2,1/2)$ and $(3/2,1)$; all of them have very similar properties. The ground state is found to be ferrimagnetic with total spin $s_G =N(s_1 - s_2)$. We find that there is a gapless excitation to a state with spin $s_G -1$, and a gapped excitation to a state with spin $s_G +1$. Surprisingly, the correlation length in the ground state is found to be very small for this gapless system. The DMRG analysis shows that the chain is susceptible to a conditional spin-Peierls instability. Furthermore, our studies of the magnetization, magnetic susceptibility $\chi$ and specific heat show strong magnetic-field dependences. The product $\chi T$ shows a minimum as a function of temperature T at low magnetic fields; the minimum vanishes at high magnetic fields. This low-field behavior is in agreement with earlier experimental observations. The specific heat shows a maximum as a function of temperature, and the height of the maximum increases sharply at high magnetic fields. Although all the three systems show qualitatively similar behavior, there are some notable quantitative differences between the systems in which the site spin difference, $|s_1 - s_2|$, is large and small respectively.Comment: 16 LaTeX pages, 13 postscript figure

Orbital maneuvering engine feed system coupled stability investigation

A digital computer model used to analyze and predict engine feed system coupled instabilities over a frequency range of 10 to 1000 Hz was developed and verified. The analytical approach to modeling the feed system hydrodynamics, combustion dynamics, chamber dynamics, and overall engineering model structure is described and the governing equations in each of the technical areas are presented. This is followed by a description of the generalized computer model, including formulation of the discrete subprograms and their integration into an overall engineering model structure. The operation and capabilities of the engineering model were verified by comparing the model's theoretical predictions with experimental data from an OMS-type engine with a known feed system/engine chugging history

Age-Related Effects on Markers of Inflammation and Cartilage Metabolism in Response to an Intra-Articular Lipopolysaccharide Challenge

Eighteen Quarter Horses were utilized in a randomized complete design for a 28 d experiment to evaluate age-related effects on inflammation and cartilage turnover after induction of a single inflammatory insult using lipopolysaccharide (LPS). Horses were grouped by age, with yearlings (yearling; n = 3 males, n = 3 females), 2 to 3 yr olds (2/3; n = 2 males, n = 4 females), and mature 5 to 8 yr olds (mature; n = 2 males, n = 4 females). On d 0, all horses were housed individually and fed diets that met or exceeded NRC (2007) requirements. On d 14, horses were challenged with an intra-articular injection of LPS. Carpal joints were randomly assigned to receive 0.5 ng LPS solution obtained from E. coli O55:B5, or 0.8mL sterile lactated Ringer’s solution as a contralateral control. Synovial fluid was collected prior to LPS injection at pre-injection h 0 (PIH 0) and 6, 12, 24, 168, and 336 h post-injection. Samples were later analyzed using commercial ELISA kits for prostaglandin E2 (PGE2), collagenase cleavage neoepitope (C2C), and carboxypropeptide of type II collagen (CPII). Heart rate (HR), respiratory rate (RR), and rectal temperature (RT) were monitored over the first 24 h and carpal circumference and surface temperature were recorded with additional measurements at 168 and 336 h. Data were analyzed using PROC MIXED procedure of SAS. Values for RT, HR, and RR were within normal range. HR and RT were influenced by age (P < 0.01), while RR was unaffected by age (P ≤ 0.21). Joint circumference was not influenced by age (P = 0.84), but circumference and surface temperature increased (P < 0.01) over time across all age groups. Synovial PGE2 concentrations tended (P = 0.09) to be influenced by age with yearlings having lower (P = 0.03) concentrations than mature horses. Synovial C2C concentrations were affected by age with yearlings and 2/3 yr olds having lower (P < 0.01) concentrations than mature horses. Concentrations of synovial CPII were influenced by age with yearlings and 2/3 yr old having lower (P ≤ 0.02) concentrations than mature horses. Ratios of CPII:C2C were influenced by age with mature and 2/3 yr old horses having increased (P < 0.01) values compared to yearlings. These results indicate that inflammation and corresponding cartilage turnover in response to LPS administration vary with age

Orbital Maneuvering Engine Feed System Coupled Stability Investigation, Computer User's Manual

An operating manual for the feed system coupled stability model was given, in partial fulfillment of a program designed to develop, verify, and document a digital computer model that can be used to analyze and predict engine/feed system coupled instabilities in pressure-fed storable propellant propulsion systems over a frequency range of 10 to 1,000 Hz. The first section describes the analytical approach to modelling the feed system hydrodynamics, combustion dynamics, chamber dynamics, and overall engineering model structure, and presents the governing equations in each of the technical areas. This is followed by the program user's guide, which is a complete description of the structure and operation of the computerized model. Last, appendices provide an alphabetized FORTRAN symbol table, detailed program logic diagrams, computer code listings, and sample case input and output data listings

Magnetic Properties of J-J-J' Quantum Heisenberg Chains with Spin S=1/2, 1, 3/2 and 2 in a Magnetic Field

By means of the density matrix renormalization group (DMRG) method, the magnetic properties of the J-J-J$^{\prime}$ quantum Heisenberg chains with spin $S=1/2$, 1, 3/2 and 2 in the ground states are investigated in the presence of a magnetic field. Two different cases are considered: (a) when $J$ is antiferromagnetic and $J^{\prime}$ is ferromagnetic (i.e. the AF-AF-F chain), the system is a ferrimagnet. The plateaus of the magnetization are observed. It is found that the width of the plateaus decreases with increasing the ferromagnetic coupling, and disappears when $$ passes over a critical value. The saturated field is observed to be independent of the ferromagnetic coupling; (b) when $J$ is ferromagnetic and $J^{\prime}$ is antiferromagnetic (i.e. the F-F-AF chain), the system becomes an antiferromagnet. The plateaus of the magnetization are also seen. The width of the plateaus decreases with decreasing the antiferromagnetic coupling, and disappears when $J^{\prime}/J$ passes over a critical value. Though the ground state properties are quite different, the magnetization plateaus in both cases tend to disappear when the ferromagnetic coupling becomes more dominant. Besides, no fundamental difference between the systems with spin half-integer and integer has been found.Comment: 8 pages, 9 figures, to be published in J. Phys.: Condens. Matte