9,118 research outputs found
Assessing the Impact of Climate Change on China's Grain Sector and International Trade
This study analyzes the potential impact of climate change on China's corn, wheat, and rice, domestic agricultural markets, and the international markets out to the year 2050. The study provides a brief background and reviews research literature of climate change effects on China's crop yields. The paper presents the potential impact of climate change on China's yields and attempts to quantify the domestic and global market impacts. The analysis has four scenarios, which assumes two future levels of greenhouse gas emissions with the effects of CO2 fertilization and no CO2 fertilization. A 27-country commodity partial equilibrium simulation mathematical programming model (PEATSim) is used for this analysis. Results indicate under CO2 fertilization, which increases yields, China's grain imports may decrease leading to a decrease in international prices. Under no CO2 fertilization, yields decrease, China's grain imports may increase leading to increased international prices.China, trade, climate change, GHG, CO2 fertilization, rice, wheat, corn, dynamic partial equilibrium simulation mathematical model., Environmental Economics and Policy, International Relations/Trade,
Validity of the Cauchy-Born rule applied to discrete cellular-scale models of biological tissues.
The development of new models of biological tissues that consider cells in a discrete manner is becoming increasingly popular as an alternative to continuum methods based on partial differential equations, although formal relationships between the discrete and continuum frameworks remain to be established. For crystal mechanics, the discrete-to-continuum bridge is often made by assuming that local atom displacements can be mapped homogeneously from the mesoscale deformation gradient, an assumption known as the Cauchy-Born rule (CBR). Although the CBR does not hold exactly for noncrystalline materials, it may still be used as a first-order approximation for analytic calculations of effective stresses or strain energies. In this work, our goal is to investigate numerically the applicability of the CBR to two-dimensional cellular-scale models by assessing the mechanical behavior of model biological tissues, including crystalline (honeycomb) and noncrystalline reference states. The numerical procedure involves applying an affine deformation to the boundary cells and computing the quasistatic position of internal cells. The position of internal cells is then compared with the prediction of the CBR and an average deviation is calculated in the strain domain. For center-based cell models, we show that the CBR holds exactly when the deformation gradient is relatively small and the reference stress-free configuration is defined by a honeycomb lattice. We show further that the CBR may be used approximately when the reference state is perturbed from the honeycomb configuration. By contrast, for vertex-based cell models, a similar analysis reveals that the CBR does not provide a good representation of the tissue mechanics, even when the reference configuration is defined by a honeycomb lattice. The paper concludes with a discussion of the implications of these results for concurrent discrete and continuous modeling, adaptation of atom-to-continuum techniques to biological tissues, and model classification
Free Time Motivation and Physical Activity in Middle School Children
This study examined free time motivation and physical activity in 68 middle school children from a rural public school system (N = 24) and a private school located in the same area of the Midwest (N = 44). Results indicated that free time motivation did not explain variability in physical activity behavior during free time or while students were in school (p \u3e .01). A school (private vs. public) x gender comparison indicated that males had higher activity levels than females during free time and while in school, F(1, 67) = 8.43, p \u3c .01, Eta2 = .12 and F(1, 67) = 27.59, p \u3c .01, Eta2 = .30. There were no differences between public versus private school participants (p \u3e . 05) on free time minutes of MVPA. Males from the study participated in 56 minutes per day while wearing activity monitors, approximating the 60 minutes recommended by health experts, t = -1.028, p \u3e .05, n = 30. Female values were significantly below this Department of Health and Human Services recommendation at 32 minutes per day, t = -7.31, p \u3c .01, n = 38
Coordinate Confusion in Conformal Cosmology
A straight-forward interpretation of standard
Friedmann-Lemaitre-Robertson-Walker (FLRW) cosmologies is that objects move
apart due to the expansion of space, and that sufficiently distant galaxies
must be receding at velocities exceeding the speed of light. Recently, however,
it has been suggested that a simple transformation into conformal coordinates
can remove superluminal recession velocities, and hence the concept of the
expansion of space should be abandoned. This work demonstrates that such
conformal transformations do not eliminate superluminal recession velocities
for open or flat matter-only FRLW cosmologies, and all possess superluminal
expansion. Hence, the attack on the concept of the expansion of space based on
this is poorly founded. This work concludes by emphasizing that the expansion
of space is perfectly valid in the general relativistic framework, however,
asking the question of whether space really expands is a futile exercise.Comment: 5 pages, accepted for publication in MNRAS Letter
China's Ongoing Agricultural Modernization: Challenges Remain After 30 Years of Reform
Thirty years ago, China began implementing a series of reforms to improve efficiency in agricultural production. These, and subsequent, reforms reshaped China’s position in the world economy. China’s rapid economic development and transformation from a planned to a market-oriented economy, however, has reached a stage where further efficiency gains in agricultural production will likely hinge on the development of modern market-supporting institutions. The development of market-supporting institutions in China will bring about long-term and sustainable benefits to producers and consumers in China and the global agricultural economy. This report provides an overview of current issues in China’s agricultural development, policy responses to these issues, and the effects of these policies on China’s growing role in international markets.China, economic reform, economic development, agricultural production, agricultural trade, Agricultural and Food Policy, International Relations/Trade, Production Economics,
Ultraviolet-Bright, High-Redshift ULIRGS
We present Spitzer Space Telescope observations of the z=2.38 lya-emitter
over-density associated with galaxy cluster J2143-4423, the largest known
structure (110 Mpc) above z=2. We imaged 22 of the 37 known lya-emitters within
the filament-like structure, using the MIPS 24um band. We detected 6 of the
lya-emitters, including 3 of the 4 clouds of extended (>50 kpc) lyman alpha
emission, also known as Lya Blobs. Conversion from rest-wavelength 7um to total
far-infrared luminosity using locally derived correlations suggests all the
detected sources are in the class of ULIRGs, with some reaching Hyper-LIRG
energies. Lya blobs frequently show evidence for interaction, either in HST
imaging, or the proximity of multiple MIPS sources within the Lya cloud. This
connection suggests that interaction or even mergers may be related to the
production of Lya blobs. A connection to mergers does not in itself help
explain the origin of the Lya blobs, as most of the suggested mechanisms for
creating Lya blobs (starbursts, AGN, cooling flows) could also be associated
with galaxy interactions.Comment: 12 pages, 3 figures, accepted by ApJ Letter
The Perspective from the Private Sector: The Institute for Tourism Development at the Rochester Institute of Technology
This article explores the development and organizational structure for a tourism center within a privately endowed university. The success of this undertaking has been directly related to the foresight of the administration and the cooperation among the faculty. Another important component of the success of this center has been private industry and their readiness to provide input, an well as dollars
Do digital hugs work? Re-embodying our social lives online with digital tact
The COVID-19 pandemic led to social restrictions that often prevented us from hugging the ones we love. This absence helped some realize just how important these interactions are to our sense of care and connection. Many turned to digitally mediated social interactions to address these absences, but often unsatisfactorily. Some theorists might blame this on the disembodied character of our digital spaces, e.g., that interpersonal touch is excluded from our lives online. However, others continued to find care and connection in their digitally mediated interactions despite not being able to touch. Inspired by such contrasting cases, we ask if ‘digital hugs’ can work? We use the Mixed Reality Interaction Matrix to examine hugging as a social practice. This leads us to several claims about the nature of our embodied social interactions and their digital mediation: (1) all social interaction is mediated; (2) all virtual experiences are embodied; (3) technology has become richer and more supportive of embodiment; and (4) expertise plays a role. These claims help make the case that quality social connections online are substantially dependent upon the dynamic skilful resourcing of multiple mediating components, what we term digital tact. By introducing and developing this concept, we hope to contribute to a better understanding of our digital embodied sociality and the possibilities for caring connections online.journal articl
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