Mathematics for structure functions

We show some of the mathematics that is being developed for the computation of deep inelastic structure functions to three loops. These include harmonic sums, harmonic polylogarithms and a class of difference equations that can be solved with the use of harmonic sums.Comment: 6 pages LaTeX, uses axodraw.sty and npb.sty (included

Soil microbial communities respond to an environmental gradient of grazing intensity in south Patagonia Argentina

Soil microorganisms communities regulate key functions in terrestrial ecosystems and contributes to the formation of stable organic matter and hence climate change mitigation. The structure, diversity and activity of soil microbial communities are influenced by the quantity and quality of organic compounds entering soils through the contribution of their root exudates and plant litter, which the microorganisms use as a substrate for biosynthesis and energy source. However, grazing effect on the soil microorganisms showed variable results dependent on the ecosystem under study. One of the main challenges of this millennium is the sustainability of agricultural production, especially in fragile soils such as those present in Patagonia. Therefore, our objective was to evaluate the responses of microbial biomass carbon (MBC), soil basal respiration (SBR), the derived coefficients and the abundance of fungi and bacteria under contrasting long-term grazing intensities in an environmental gradient. The study was established in three ecological areas Mata Negra Thicket (MNT), Dry Magellanic Steppe (DMS) and Humid Magellanic Steppe (HMS) with two grazing intensities. Soil samples were taken over two years in different seasons (autumn, winter, spring and summer). Results showed that biotic and abiotic factors (temperature and precipitation), plant communities and soil characteristics modulated the microbial structure and function in ecological area. On the other hand, high grazing intensity decreased the MBC and microbial coefficient (qM). There was a seasonal and interannual dynamic in the MBC and the bacteria and fungal communities, attributed mainly to temperature and precipitation. The results indicated that the effect of grazing intensity in soil microbial communities depends largely on intrinsic characteristics of each ecological area defined by the environmental gradient.EEA Santa CruzFil: Toledo, Santiago. Universidad Nacional de la Patagonia Austral; Argentina.Fil: Peri, Pablo Luis. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina.Fil: Correa, Olga S. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Biología Aplicada y Alimentos; ArgentinaFil: Gargaglione, Veronica Beatriz. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina.Fil: Gonzalez Polo, Marina. Consejo Nacional de Investigaciones Cientificas y Tecnicas.Fil: Toledo, Santiago. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Peri, Pablo Luis. Universidad Nacional de la Patagonia Austral; Argentina.Fil: Peri, Pablo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gargaglione, Veronica Beatriz. Universidad Nacional de la Patagonia Austral; Argentina.Fil: Gargaglione, Veronica Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gonzalez Polo, Marina. Universidad Nacional del Comahue. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentin

Stellar 36,38^{36,38}Ar(n,γ)37,39(n,\gamma)^{37,39}Ar reactions and their effect on light neutron-rich nuclide synthesis

The $^{36}$Ar$(n,\gamma)^{37}$Ar ($t_{1/2}$ = 35 d) and $^{38}$Ar$(n,\gamma)^{39}$Ar (269 y) reactions were studied for the first time with a quasi-Maxwellian ($kT \sim 47$ keV) neutron flux for Maxwellian Average Cross Section (MACS) measurements at stellar energies. Gas samples were irradiated at the high-intensity Soreq applied research accelerator facility-liquid-lithium target neutron source and the $^{37}$Ar/$^{36}$Ar and $^{39}$Ar/$^{38}$Ar ratios in the activated samples were determined by accelerator mass spectrometry at the ATLAS facility (Argonne National Laboratory). The $^{37}$Ar activity was also measured by low-level counting at the University of Bern. Experimental MACS of $^{36}$Ar and $^{38}$Ar, corrected to the standard 30 keV thermal energy, are 1.9(3) mb and 1.3(2) mb, respectively, differing from the theoretical and evaluated values published to date by up to an order of magnitude. The neutron capture cross sections of $^{36,38}$Ar are relevant to the stellar nucleosynthesis of light neutron-rich nuclides; the two experimental values are shown to affect the calculated mass fraction of nuclides in the region A=36-48 during the weak $s$-process. The new production cross sections have implications also for the use of $^{37}$Ar and $^{39}$Ar as environmental tracers in the atmosphere and hydrosphere.Comment: 18 pages + Supp. Mat. (13 pages) Accepted for publication in Phys. Rev. Let

Probing the single-particle character of rotational states in 19^{19}F using a short-lived isomeric beam

A beam containing a substantial component of both the $J^{\pi}=5^+$, $T_{1/2}=162$ ns isomeric state of $^{18}$F and its $1^+$, 109.77-min ground state has been utilized to study members of the ground-state rotational band in $^{19}$F through the neutron transfer reaction $(d$,$p)$ in inverse kinematics. The resulting spectroscopic strengths confirm the single-particle nature of the 13/2$^+$ band-terminating state. The agreement between shell-model calculations, using an interaction constructed within the $sd$ shell, and our experimental results reinforces the idea of a single-particle/collective duality in the descriptions of the structure of atomic nuclei

Human Developmental Chondrogenesis as a Basis for Engineering Chondrocytes from Pluripotent Stem Cells

Joint injury and osteoarthritis affect millions of people worldwide, but attempts to generate articular cartilage using adult stem/progenitor cells have been unsuccessful. We hypothesized that recapitulation of the human developmental chondrogenic program using pluripotent stem cells (PSCs) may represent a superior approach for cartilage restoration. Using laser-capture microdissection followed by microarray analysis, we first defined a surface phenotype (CD166(low/neg)CD146(low/neg)CD73(+)CD44(low)BMPR1B(+)) distinguishing the earliest cartilage committed cells (prechondrocytes) at 5-6 weeks of development. Functional studies confirmed these cells are chondrocyte progenitors. From 12 weeks, only the superficial layers of articular cartilage were enriched in cells with this progenitor phenotype. Isolation of cells with a similar immunophenotype from differentiating human PSCs revealed a population of CD166(low/neg)BMPR1B(+) putative cartilage-committed progenitors. Taken as a whole, these data define a developmental approach for the generation of highly purified functional human chondrocytes from PSCs that could enable substantial progress in cartilage tissue engineering.Fil: Wu, Ling. University of California at Los Angeles; Estados UnidosFil: Bluguermann, Carolina. Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia. Laboratorio de Biología del Desarrollo Celular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. University of California at Los Angeles; Estados UnidosFil: Kyupelyan, Levon. University of California at Los Angeles; Estados UnidosFil: Latour, Brooke. University of California at Los Angeles; Estados UnidosFil: Gonzalez, Stephanie. University of California at Los Angeles; Estados UnidosFil: Shah, Saumya. University of California at Los Angeles; Estados UnidosFil: Galic, Zoran. University of California at Los Angeles; Estados UnidosFil: Ge, Sundi. University of California at Los Angeles; Estados UnidosFil: Zhu, Yuhua. University of California at Los Angeles; Estados UnidosFil: Petrigliano, Frank A.. University of California at Los Angeles; Estados UnidosFil: Nsair, Ali. University of California at Los Angeles; Estados UnidosFil: Miriuka, Santiago Gabriel. Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia. Laboratorio de Biología del Desarrollo Celular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Li, Xinmin. University of California at Los Angeles; Estados UnidosFil: Lyons, Karen M.. University of California at Los Angeles; Estados UnidosFil: Crooks, Gay M.. University of California at Los Angeles; Estados UnidosFil: McAllister, David R.. University of California at Los Angeles; Estados UnidosFil: Van Handel, Ben. Novogenix Laboratories; Estados UnidosFil: Adams, John S.. University of California at Los Angeles; Estados UnidosFil: Evseenko, Denis. University of California at Los Angeles; Estados Unido

Non-Singlet Structure Functions at Three Loops: Fermionic Contributions

We compute the fermionic (n_f) contributions to the flavour non-singlet structure functions in unpolarized electromagnetic deep-inelastic scattering at third order of massless perturbative QCD. Complete results are presented for the corresponding nf-parts of the three-loop anomalous dimension and the three-loop coefficient functions for the structure functions F_2 and F_L. Our results agree with all partial and approximate results available in the literature. The present calculation also facilitates a complete determination of the threshold-resummation parameters B_2 and D_2^DIS of which only the sum was known so far, thus completing the information required for the next-to-next-to-leading logarithmic resummation. We find that D_2^DIS vanishes in the MSbar scheme.Comment: 20 pages, LaTeX, 1 eps-figur

High consumption of ultra-processed foods is associated with increased risk of micronutrient inadequacy in children: The SENDO project

Due to its rising prevalence, which parallels that of ultraprocessed food (UPF) consumption, inadequate micronutrient intake in childhood is a public health concern. This study aimed to evaluate the association between UPF consumption and inadequate intake of 20 micronutrients in a sample of children from the Mediterranean area. Cross-sectional information from participants in the “Seguimiento del Niño para un Desarrollo Óptimo” (SENDO) project 2015–2021 was used. Dietary information was gathered with a previously validated 147-item semi-quantitative food frequency questionnaire and the NOVA system was used to classify food items. Children were classifed by tertiles of energy intake from UPF. Twenty micronutrients were evaluated, and inadequate intake was defned using the estimated average requirement as a cutof. Crude and multivariable adjusted OR (95% CI) for the inadequacy of≥3 micronutrients associated with UPF consumption were calculated ftting hierarchical models to take into account intra-cluster correlation between siblings. Analyses were adjusted for individual and family confounders. This study included 806 participants (51% boys) with a mean age of 5 years old (SD: 0.90) and an average energy intake from UPF of 37.64% (SD: 9.59). An inverse association between UPF consumption and the intake of 15 out of the 20 micronutrients evaluated was found (p<0.01). After the adjustment for individual and family confounders, compared with children in the frst tertile of UPF consumption, those in the third tertile showed higher odds of inadequate intake of≥3 micronutrients (OR 2.57; 95%CI [1.51–4.40]). Conclusion: High UPF consumption is associated with increased odds of inadequate intake of micronutrients in childhood

Key 19^{19}Ne states identified affecting γ\gamma-ray emission from 18^{18}F in novae

Detection of nuclear-decay $\gamma$ rays provides a sensitive thermometer of nova nucleosynthesis. The most intense $\gamma$-ray flux is thought to be annihilation radiation from the $\beta^+$ decay of $^{18}$F, which is destroyed prior to decay by the $^{18}$F($p$,$\alpha$)$^{15}$O reaction. Estimates of $^{18}$F production had been uncertain, however, because key near-threshold levels in the compound nucleus, $^{19}$Ne, had yet to be identified. This Letter reports the first measurement of the $^{19}$F($^{3}$He,$t\gamma$)$^{19}$Ne reaction, in which the placement of two long-sought 3/2$^+$ levels is suggested via triton-$\gamma$-$\gamma$ coincidences. The precise determination of their resonance energies reduces the upper limit of the rate by a factor of $1.5-17$ at nova temperatures and reduces the average uncertainty on the nova detection probability by a factor of 2.1.Comment: 6 pages, 4 figure

New γ\gamma-ray Transitions Observed in 19^{19}Ne with Implications for the 15^{15}O(α\alpha,γ\gamma)19^{19}Ne Reaction Rate

The $^{15}$O($\alpha$,$\gamma$)$^{19}$Ne reaction is responsible for breakout from the hot CNO cycle in Type I x-ray bursts. Understanding the properties of resonances between $E_x = 4$ and 5 MeV in $^{19}$Ne is crucial in the calculation of this reaction rate. The spins and parities of these states are well known, with the exception of the 4.14- and 4.20-MeV states, which have adopted spin-parities of 9/2$^-$ and 7/2$^-$, respectively. Gamma-ray transitions from these states were studied using triton-$\gamma$-$\gamma$ coincidences from the $^{19}$F($^{3}$He,$t\gamma$)$^{19}$Ne reaction measured with GODDESS (Gammasphere ORRUBA Dual Detectors for Experimental Structure Studies) at Argonne National Laboratory. The observed transitions from the 4.14- and 4.20-MeV states provide strong evidence that the $J^\pi$ values are actually 7/2$^-$ and 9/2$^-$, respectively. These assignments are consistent with the values in the $^{19}$F mirror nucleus and in contrast to previously accepted assignments

Independent measurement of the Hoyle state β\beta feeding from 12B using Gammasphere

Using an array of high-purity Compton-suppressed germanium detectors, we performed an independent measurement of the $\beta$-decay branching ratio from $^{12}\mathrm{B}$ to the second-excited (Hoyle) state in $^{12}\mathrm{C}$. Our result is $0.64(11)\%$, which is a factor $\sim 2$ smaller than the previously established literature value, but is in agreement with another recent measurement. This could indicate that the Hoyle state is more clustered than previously believed. The angular correlation of the Hoyle state $\gamma$ cascade has also been measured for the first time. It is consistent with theoretical predictions