On the Uniform Decay of the Local Energy

It is proved in [1],[2] that in odd dimensional spaces any uniform decay of the local energy implies that it must decay exponentially. We extend this to even dimensional spaces and to more general perturbations (including the transmission problem) showing that any uniform decay of the local energy implies that it must decay like O(t^(−2n) ), t ≫ 1 being the time and n being the space dimension.

Local Energy Decay in Even Dimensions for the Wave Equation with a Time-Periodic Non-Trapping Metric and Applications to Strichartz Estimates

2000 Mathematics Subject Classification: 35B40, 35L15.

Exotic meson decay widths using lattice quantum chromodynamics

Most experiments in particle physics are scattering experiments, the analysis of which leads to masses, scattering phases, decay widths and other properties of one or multi-particle systems. Until the advent of Lattice Quantum Chromodynamics (LQCD) it was difficult to compare experimental results on low energy hadron-hadron scattering processes to the predictions of QCD, the current theory of strong interactions. The reason being, at low energies the QCD coupling constant becomes large and the perturbation expansion for scattering; amplitudes does not converge. To overcome this, one puts the theory onto a lattice, imposes a momentum cutoff, and computes the integral numerically. For particle masses, predictions of LQCD agree with experiment, but the area of decay widths is largely unexplored. ^ LQCD provides ab initio access to unusual hadrons like exotic mesons that are predicted to contain real gluonic structure. To study decays of these type resonances the energy spectra of a two-particle decay state in a finite volume of dimension L can be related to the associated scattering phase shift δ(k) at momentum k through exact formulae derived by Lüscher. Because the spectra can be computed using numerical Monte Carlo techniques, the scattering phases can thus be determined using Lüscher's formulae, and the corresponding decay widths can be found by fitting Breit-Wigner functions. ^ Results of such a decay width calculation for an exotic hybrid( h) meson (JPC = 1-+) are presented for the decay channel h → πa 1. This calculation employed Lüscher's formulae and an approximation of LQCD called the quenched approximation. Energy spectra for the h and πa1 systems were extracted using eigenvalues of a correlation matrix, and the corresponding scattering phase shifts were determined for a discrete set of πa1 momenta. Although the number of phase shift data points was sparse, fits to a Breit-Wigner model were made, resulting in a decay width of about 60 MeV. ^

Temporally dependent C, N, and P dynamics associated with the decay of Rhizophora mangle L. leaf litter in oligotrophic mangrove wetlands of the Southern Everglades

We performed two litter decomposition experiments using nearly-senesced red mangrove (Rhizophora mangle L.) leaves collected from an Everglades dwarf mangrove wetland to understand the short-term (3 weeks) and long-term (1 year) changes in mass, as well as C-, N-, and P-content of decomposing leaf litter. We expected that leaves decomposing in this oligotrophic environment would be short-term sources of C, N, and P, but potential long-term sinks for N and P. In May 1998, we conducted a 3-week leaching experiment, incubating fresh, individual leaves in seawater for up to 21 days. From May 1997 to May 1998, leaf litter in mesh bags decomposed on the forest floor at two dwarf mangrove sites. Leaching accounted for about 33% loss of dry mass from R. mangle leaves after 3 weeks. Leaching losses were rapid, peaking by day 2, and large, with leachate concentrations of total organic carbon (TOC) and total phosphorus (TP) increasing by more than an order of magnitude after 3 weeks. Mean leaf C:N increased from 105 to 115 and N:P increased from a mean of 74 to 95 after 21 days, reflecting the relatively large leaching losses of N and P. Loss of mass in the litterbags leveled off after 4 months, with roughly 60%dry mass remaining (DMR) after nearly 1 year of decomposition. The mass of carbon in each litterbag declined significantly after 361 days, but the mass of nitrogen and phosphorus doubled, indicating long-term accumulation of these constituents into the detritus. Subsequently, the leaf C:N ratio dropped significantly from 90 to 34 after 361 days. Following an initial 44-day increase, leaf N:P decreased from 222 to 144, reflecting high accumulation of P relative to N. A review of several estuarine macrophyte decomposition studies reveals a trend in nitrogen accumulation through time regardless of site, but suggests no clear pattern for C and P. We believe that the increase in litter P observed in this study was indicative of the P-limited status of the greater Everglades ecosystem and that decomposing mangrove litter may represent a substantial phosphorus pool in the system.

The contribution of leaching to the rapid release of nutrients and carbon in the early decay of wetland vegetation

Our goal was to quantify the coupled process of litter turnover and leaching as a source of nutrients and fixed carbon in oligotrophic, nutrient-limited wetlands. We conducted poisoned and non-poisoned incubations of leaf material from four different perennial wetland plants (Eleocharis spp., Cladium jamaicense, Rhizophora mangle and Spartina alterniflora) collected from different oligotrophic freshwater and estuarine wetland settings. Total phosphorus (TP) release from the P-limited Everglades plant species (Eleocharis spp., C. jamaicense and R. mangle) was much lower than TP release by the salt marsh plant S. alterniflora from N-limited North Inlet (SC). For most species and sampling times, total organic carbon (TOC) and TP leaching losses were much greater in poisoned than non-poisoned treatments, likely as a result of epiphytic microbial activity. Therefore, a substantial portion of the C and P leached from these wetland plant species was bio-available to microbial communities. Even the microbes associated with S. alterniflora from N-limited North Inlet showed indications of P-limitation early in the leaching process, as P was removed from the water column. Leaves of R. mangle released much more TOC per gram of litter than the other species, likely contributing to the greater waterborne [DOC] observed by others in the mangrove ecotone of Everglades National Park. Between the two freshwater Everglades plants, C. jamaicense leached nearly twice as much P than Eleocharis spp. In scaling this to the landscape level, our observed leaching losses combined with higher litter production of C. jamaicense compared to Eleocharis spp. resulted in a substantially greater P leaching from plant litter to the water column and epiphytic microbes. In conclusion, leaching of fresh plant litter can be an important autochthonous source of nutrients in freshwater and estuarine wetland ecosystems.

Characterization of a new toxin from the entomopathogenic fungus Metarhizium anisopliae: the ribotoxin anisoplin

Metarhizium anisopliae is an entomopathogenic fungus relevant in biotechnology with applications like malaria vector control. Studies of its virulence factors are therefore of great interest. Fungal ribotoxins are toxic ribonucleases with extraordinary efficiency against target ribosomes and suggested as potential insecticides. Here, we describe this ribotoxin characteristic activity in M. anisopliae cultures. Anisoplin has been obtained as a recombinant protein and further characterized. It is structurally similar to hirsutellin A, the ribotoxin from the entomopathogen Hirsutella thompsonii. Moreover, anisoplin shows the ribonucleolytic activity typical of ribotoxins and cytotoxicity against insect cells. How Metarhizium uses this toxin and possible applications are on perspective.

Economic contribution of Chinese caterpillar fungus to the livelihoods of mountain communities in Nepal

Harvesting of Chinese caterpillar fungus, one of the most expensive biological commodities in the world, has become an important livelihood strategy for mountain communities of Nepal. However, very little is known about the role of Chinese caterpillar fungus in household economy. We estimated the economic contribution of Chinese caterpillar fungus to the household income, quantified the extent of "Chinese caterpillar fungus dependence" among households with different economic and social characteristics, and assessed the role of cash income from the Chinese caterpillar fungus harvest in meeting various household needs including education, debt payments, and food security. Results show that Chinese caterpillar fungus income is the second largest contributor to the total household income after farm income with 21.1% contribution to the total household income and 53.3% to the total cash income. The contribution of Chinese caterpillar fungus income to total household income decreases as the household income increases making its contribution highest for the poorest households. There is significant correlation between Chinese caterpillar fungus dependency and percentage of family members involved in harvesting, number of food-sufficient months, and total income without Chinese caterpillar fungus income. Income from Chinese caterpillar fungus is helping the poorest to educate children, purchase food, and pay debts. However, reported decline of Chinese caterpillar fungus from its natural habitat might threaten local livelihoods that depend on the Chinese caterpillar fungus in future. Therefore, sustainable management of Chinese caterpillar fungus through partnership among local institutions and the state is critical in conserving the species and the sustained flow of benefits to local communities.

Background Measurement Techniques and Sensitivity Studies for the SNO+ Neutrinoless Double Beta Decay Search

The control of radioactive backgrounds will be key in the search for neutrinoless double beta decay at the SNO+ experiment. Several aspects of the SNO+ back- grounds have been studied. The SNO+ tellurium purification process may require ultra low background ethanol as a reagent. A low background assay technique for ethanol was developed and used to identify a source of ethanol with measured 238U and 232Th concentrations below 2.8 10^-13 g/g and 10^-14 g/g respectively. It was also determined that at least 99:997% of the ethanol can be removed from the purified tellurium using forced air ow in order to reduce 14C contamination. In addition, a quality-control technique using an oxygen sensor was studied to monitor 222Rn contamination due to air leaking into the SNO+ scintillator during transport. The expected sensitivity of the technique is 0.1mBq/L or better depending on the oxygen sensor used. Finally, the dependence of SNO+ neutrinoless double beta decay sensitivity on internal background levels was studied using Monte Carlo simulation. The half-life limit to neutrinoless double beta decay of 130Te after 3 years of operation was found to be 4.8 1025 years under default conditions.

Energy level decay and excited state absorption processes in erbium-doped tellurium glass

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Energy level decay and excited state absorption processes in dysprosium-doped fluoride glass

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Energy transfer and energy level decay processes in Tmsup(3+)-doped tellurite glass

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Natural colonization of loggerhead turtle eggs by the pathogenic fungus Fusarium oxysporum

[EN] Sea turtle nests are exposed to different environmental risks that may affect their hatching success. Human exploitation, predation by wild or domestic animals, nest flooding or severe beach erosion or accession are common causes of egg mortality. However, there is very little information about the impact of microorganisms on turtle eggs. We analyzed loggerhead turtle eggs from Boavista Island (Republic of Cabo Verde) which were incubated under different environmental conditions in order to evaluate the presence and impact of fungus. We have isolated Fusarium oxysporum from dead and live eggs after three days of incubation.

Contrived Dereliction: Employing an aesthetic of decay at mining heritage sites

Conventional descriptions place conservation activities between the two poles of active restorative intervention and passive abandonment. This paper proposes that site stewards at mining heritage sites often follow presentation strategies that sit outside this neat dualism. Drawing on material presented in the form of three case studies, this paper identifies the actions these strategies entail and considers the results in terms of an aesthetic of decay. To consolidate the argument, a new overarching term is introduced to describe this strategy: contrived dereliction, in order to foreground its essential features. The paper then outlines the advantages, limitations and requirements of contrived dereliction as a heritage management and presentation practice.