EDUCATIONAL AND OCCUPATIONAL PLANS OF FARM BOYS IN 1967

Labor and Human Capital,

MEASURING PRODUCTIVITY CHANGE IN U.S. AGRICULTURE

Productivity Analysis,

One loop amplitude from null string

We generalize the CHY formalism to one-loop level, based on the framework of the null string theory. The null string, a tensionless string theory, produces the same results as the ones from the chiral ambitwistor string theory, with the latter believed to give a string interpretation of the CHY formalism. A key feature of our formalism is the interpretation of the modular parameters. We find that the $S$ modular transformation invariance of the ordinary string theory does not survive in the case of the null string theory. Treating the integration over the modular parameters this way enable us to derive the n-gons scattering amplitude in field theory, thus proving the n-gons conjecture.Comment: 18 pages, 2 figure

Quantum replication at the Heisenberg limit

No process in nature can perfectly clone an arbitrary quantum state. But is it possible to engineer processes that replicate quantum information with vanishingly small error? Here we demonstrate the possibility of probabilistic super-replication phenomena where N equally prepared quantum clocks are transformed into a much larger number of M nearly perfect replicas, with an error that rapidly vanishes whenever M is small compared to the square of N. The quadratic replication rate is the ultimate limit imposed by Quantum Mechanics to the proliferation of information and is fundamentally linked with the Heisenberg limit of quantum metrology.Comment: 9 + 16 pages, 2 figures, published versio

Abscisic Acid Regulation of Branching

Axillary meristem production and activity contribute to the high plasticity of plant development which allows plants to respond to environmental changes. Branches arise from axillary buds that form in the leaf axil. These buds may remain dormant, or may grow out to form branches immediately. Alternatively, the axillary buds may also persist in a dormant state for an indefinite period of time until appropriate signals permit outgrowth to commence. Branching is regulated by phytohormones, including auxin acting via the polar auxin transport stream, and locally within the bud by the action of branching integrators like BRC1and MAX2. Branchingis also regulated by environmental factors such as competition signals (low Red light: Far-Red light [R: FR])that inhibit bud outgrowth. Our recent studies indicate that ABA acts within the bud tosuppress outgrowth. NCED3 is a key enzyme in the ABA biosynthesis pathway, and ABA2 is another importantABA biosynthesisgene.ABA accumulatedtosignificantly higher levels in lower, more dormantbudscompared to less dormant buds at higher rosette positions. Additionally, bud ABA content and the correlative inhibition index, whichis a measure of systemic branching suppression, were increased in plants grown under low R:FR compared to those grown under high R:FR. Under low R:FR the NCED3 deficient mutantnced3-2and the ABA2 deficient mutant aba2-1had significantly more branches and lower correlative inhibition index thanWT. The results indicate that the suppression of branching by low R:FR may be mediated, at least in part, by elevated levels of ABA in the buds

A comparison of PM exposure related to emission hotspots in a hot and humid urban environment: Concentrations, compositions, respiratory deposition, and potential health risks

Particle number concentration, particle size distribution, and size-dependent chemical compositions were measured at a bus stop, alongside a high way, and at an industrial site in a tropical city. It was found that the industry case had 4.93 × 107–7.23 × 107 and 3.44 × 104–3.69 × 104 #/m3 higher concentration of particles than the bus stop and highway cases in the range of 0.25–0.65 μm and 2.5–32 μm, respectively, while the highway case had 6.01 × 105 and 1.86 × 103 #/m3 higher concentration of particles than the bus stop case in the range of 0.5–1.0 μm and 5.0–32 μm, respectively. Al, Fe, Na, and Zn were the most abundant particulate inorganic elements for the traffic-related cases, while Zn, Mn, Fe, and Pb were abundant for the industry case. Existing respiratory deposition models were employed to analyze particle and element deposition distributions in the human respiratory system with respect to some potential exposure scenarios related to bus stop, highway, and industry, respectively. It was shown that particles of 0–0.25 μm and 2.5–10.0 μm accounted for around 74%, 74%, and 70% of the particles penetrating into the lung region, respectively. The respiratory deposition rates of Cr and Ni were 170 and 220 ng/day, and 55 and 140 ng/day for the highway and industry scenarios, respectively. Health risk assessment was conducted following the US EPA supplemented guidance to estimate the risk of inhalation exposure to the selected elements (i.e. Cr, Mn, Ni, Pb, Se, and Zn) for the three scenarios. It was suggested that Cr poses a potential carcinogenic risk with the excess lifetime cancer risk (ELCR) of 2.1–98 × 10− 5 for the scenarios. Mn poses a potential non-carcinogenic risk in the industry scenario with the hazard quotient (HQ) of 0.98. Both Ni and Mn may pose potential non-carcinogenic risk for people who are involved with all the three exposure scenarios