648 research outputs found
Identifying the community structure of the international food-trade multi network
Achieving international food security requires improved understanding of how
international trade networks connect countries around the world through the
import-export flows of food commodities. The properties of food trade networks
are still poorly documented, especially from a multi-network perspective. In
particular, nothing is known about the community structure of food networks,
which is key to understanding how major disruptions or 'shocks' would impact
the global food system. Here we find that the individual layers of this network
have densely connected trading groups, a consistent characteristic over the
period 2001 to 2011. We also fit econometric models to identify social,
economic and geographic factors explaining the probability that any two
countries are co-present in the same community. Our estimates indicate that the
probability of country pairs belonging to the same food trade community depends
more on geopolitical and economic factors -- such as geographical proximity and
trade agreements co-membership -- than on country economic size and/or income.
This is in sharp contrast with what we know about bilateral-trade determinants
and suggests that food country communities behave in ways that can be very
different from their non-food counterparts.Comment: 47 pages, 19 figure
Selected underconsumption theories and the business cycle.
Thesis (M.A.)--Boston UniversityAn attempt has been made in this thesis to indicate that the underlying issues of the underconsumption analysis are essentially correct, that these selected underconsumption theories are characterized by the feeling that investment outruns consumption in the existing system. The manner by which to overcome this situation is to stimulate consumption by either increasing the share of income as proposed by the distribution school, or by means of monetary manipulation as advanced by the monetary school. This paper also points out that the modern underconsumption writers anticipated the tools now used in a modern business cycle approach. They did not have them; they approached them and, therefore, were on the right track. This particular business cycle approach as accepted by A. Hansen, J. Hicks, and R. Harrod integrates many theories of the business cycle into one by the use of three tools - the marginal efficiency schedule in relation to the rate of interest, the role of investment multiplier based upon the consumption function, and the principle of acceleration, i.e., the effect of change in income in respect to the rate of investment. This modern theory synthesizes the various and seemingly conflicting opinions of business cycle theorists; with one stroke it takes into consideration the role of money, the role of investment, and the role of consumption. [TRUNCATED
Correlation functions of the One-Dimensional Random Field Ising Model at Zero Temperature
We consider the one-dimensional random field Ising model, where the spin-spin
coupling, , is ferromagnetic and the external field is chosen to be
with probability and with probability . At zero temperature, we
calculate an exact expression for the correlation length of the quenched
average of the correlation function in the case that is not an integer. The
result is a discontinuous function of . When , we also
place a bound on the correlation length of the quenched average of the
correlation function .Comment: 12 pages (Plain TeX with one PostScript figure appended at end), MIT
CTP #220
Susceptibility of South Korea to Extremes Affecting the Global Food System
Food security in South Korea is tightly linked to the global food system. The country's production of major grains declined from 5.8 million metric tons (mmt) in 1998 to 4.8 mmt in 2014, which caused the country's grain self suciency to decline from 31.4% to 24%. This decline is a consequence of several factors including reductions in domestic agricultural land, governmental policies supporting industry over agriculture, and a push towards trade liberalization. South Korea's self suciency is now one of the lowest among Organisation for Economic Co-operation and Development (OECD) countries, leaving it vulnerable to disruptions in the global food system
Mediastinitis and sternal prosthesis infection successfully treated by minimally invasive omental flap transposition
Purulent mediastinitis is a possible serious complication after mediastinal surgery. We report the case of a localized
sternal plasmocytoma treated by sternectomy and prosthetic repair, who needed a second surgery for a fistulizing
mediastinitis. Five months earlier, in another Hospital, the patient underwent sternal resection and reconstruction
with a “sandwich” prosthesis (Methyl-methacrylate and Marlex mesh). Suppurative mediastinitis occurred and septic
shock resolution was observed after the spontaneous opening of a mediastinal cutaneous fistula. After referring to
our Unit the patient underwent extensive local and systemic preparation and nutritional support; the infected
prosthesis was then removed and the gap filled by a laparoscopically-prepared omental flap. Adequate
preoperative management, removal of any infected material and minimally invasive omental flap transposition
allowed the successful treatment of this life-threatening condition
Diagnosis and endovascular treatment of an internal mammary artery injury
Internal mammary artery (IMA) disruption after blunt chest trauma is rare. In some instances, it may occur after
mild chest trauma with minor external physical findings. However, prompt diagnosis and treatment are necessary,
as it can be associated with vascular and parenchymal injuries.
We report a case of blunt chest trauma resulting in a sternal fracture associated with an IMA injury, active
anterior mediastinal bleeding, bilateral lung contusions, and a left hemothorax. It was successfully treated by selective
embolization to the left IMA branch and chest tube placement
Irrigation Induced Surface Cooling in the Context of Modern and Increased Greenhouse Gas Forcing
There is evidence that expected warming trends from increased greenhouse gas (GHG) forcing have been locally masked by irrigation induced cooling, and it is uncertain how the magnitude of this irrigation masking effect will change in the future. Using an irrigation dataset integrated into a global general circulation model, we investigate the equilibrium magnitude of irrigation induced cooling under modern (Year 2000) and increased (A1B Scenario, Year 2050) GHG forcing, using modern irrigation rates in both scenarios. For the modern scenario, the cooling is largest over North America, India, the Middle East, and East Asia. Under increased GHG forcing, this cooling effect largely disappears over North America, remains relatively unchanged over India, and intensifies over parts of China and the Middle East. For North America, irrigation significantly increases precipitation under modern GHG forcing; this precipitation enhancement largely disappears under A1B forcing, reducing total latent heat fluxes and the overall irrigation cooling effect. Over India, irrigation rates are high enough to keep pace with increased evaporative demand from the increased GHG forcing and the magnitude of the cooling is maintained. Over China, GHG forcing reduces precipitation and shifts the region to a drier evaporative regime, leading to a relatively increased impact of additional water from irrigation on the surface energy balance. Irrigation enhances precipitation in the Middle East under increased GHG forcing, increasing total latent heat fluxes and enhancing the irrigation cooling effect. Ultimately, the extent to which irrigation will continue to compensate for the warming from increased GHG forcing will primarily depend on changes in the background evaporative regime, secondary irrigation effects (e.g. clouds, precipitation), and the ability of societies to maintain (or increase) current irrigation rates
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