3,931 research outputs found
Occurrence of Stolbur phytoplasma in the vector Hyalesthes obsoletus, herbaceous host plants and grapevine in South Tyrol (Northern Italy)
Bois noir (BN) is a grapevine yellows disease caused by a phytoplasma of the Stolbur group (16SrXII-A). The planthopper Hyalesthes obsoletus is known to be the principal vector and can accidentally transmit the phytoplasma from its herbaceous host plants to grapevine (Vitis vinifera). Due to the increasing incidence of BN over the last decade, a monitoring study was conducted in South Tyrol (Northern Italy). Over a period of up to four years, 659 insect vector samples, 516 herbaceous plants of 41 potential host plant species as well as 56 grapevine samples from BN-affected vineyards were tested for the presence of the Stolbur phytoplasma using a nested PCR procedure. In addition, a recently developed TaqMan allelic discrimination assay was employed to determine different subtypes of BN in infected samples. The Stolbur phytoplasma could be detected in all three sample types analysed, and was shown to belong to two different subtypes, VK type I and VK type II. In most vineyards one subtype was found to be predominant. The average infection rate of H. obsoletus amounted to 24.1 %. Analysis of herbaceous plants revealed that 25.1 % of the Convolvulus arvensis samples tested positive for the BN phytoplasma, as well as 4.5 % of the Urtica dioica samples. Taken together, our results underline the role of these two species commonly found in the undergrowth vegetation of South Tyrolean vineyards as an important reservoir of the Stolbur phytoplasma.
Maskless, Direct Deposition of Copper Onto Aluminum Bond Pads for Flip Chip Applications
Flip chip interconnection of integrated circuits (IC) for packaging applications such as direct chip attachment use Pb-Sn solders as the connection between the die and the substrate. Under bump metallization is typically used to transition from the non-solderable Al bond pad on the IC to a solderable surface such as copper using traditional blanket metal deposition, photolithography and etching procedures. In this study, we report for the first time the use of a novel process for selectively depositing adherent copper directly onto aluminum thin films, eliminating the need for adhesion promoting transition layers and additional patterning steps. Utilizing copper bearing organic solutions and standard electroless and electrolytic copper plating baths, as-deposited and annealed sputter deposited Al-x%Cu (x = 0 to 2) thin films were coated with metallic copper. An increase in the organically deposited copper nucleation site density was observed with increasing copper concentration in the sputtered aluminum/copper thin films. Preliminary results using focused ion beam microscopy indicated that dissolution of the aluminum oxide surface and subsequent deposition of copper by cementation occurs in the non-conducting organic solution at sub-micron reaction lengths. Qualitative adhesion testing of samples resulted in the majority of films passing the tape test. Demonstration of the process using 50-micron diameter vias in BCB coated flip chip test vehicles from MCNC will be presented
Isolation of Isotrichophycin C and Trichophycins GâI from a Collection of Trichodesmium thiebautii
The trichophycin family of compounds are chlorinated polyketides first discovered from environmental collections of a bloom-forming Trichodesmium sp. cyanobacterium. In an effort to fully capture the chemical space of this group of metabolites, the utilization of MS/MS-based molecular networking of a Trichodesmium thiebautii extract revealed a metabolome replete with halogenated compounds. Subsequent MS-guided isolation resulted in the characterization of isotrichophycin C and trichophycins GâI (1â4). These new metabolites had intriguing structural variations from those trichophycins previously characterized, which allowed for a comparative study to examine structural features that are associated with toxicity to murine neuroblastoma cells. Additionally, we propose the absolute configuration of the previously characterized trichophycin A (5). Overall, the metabolome of the Trichodesmium bloom is hallmarked by an unprecedented amount of chlorinated molecules, many of which remain to be structurally characterized
Local comparison of protein structures highlights cases of convergent evolution in analogous functional sites
We performed an exhaustive search for local structural similarities in an ensemble of non-redundant protein functional sites. With the purpose of finding new examples of convergent evolution, we selected only those matching sites composed of structural regions whose residue order is inverted in the relative protein sequences
Evidence for the role of EPHX2 gene variants in anorexia nervosa.
Anorexia nervosa (AN) and related eating disorders are complex, multifactorial neuropsychiatric conditions with likely rare and common genetic and environmental determinants. To identify genetic variants associated with AN, we pursued a series of sequencing and genotyping studies focusing on the coding regions and upstream sequence of 152 candidate genes in a total of 1205 AN cases and 1948 controls. We identified individual variant associations in the Estrogen Receptor-Ă (ESR2) gene, as well as a set of rare and common variants in the Epoxide Hydrolase 2 (EPHX2) gene, in an initial sequencing study of 261 early-onset severe AN cases and 73 controls (P=0.0004). The association of EPHX2 variants was further delineated in: (1) a pooling-based replication study involving an additional 500 AN patients and 500 controls (replication set P=0.00000016); (2) single-locus studies in a cohort of 386 previously genotyped broadly defined AN cases and 295 female population controls from the Bogalusa Heart Study (BHS) and a cohort of 58 individuals with self-reported eating disturbances and 851 controls (combined smallest single locus P<0.01). As EPHX2 is known to influence cholesterol metabolism, and AN is often associated with elevated cholesterol levels, we also investigated the association of EPHX2 variants and longitudinal body mass index (BMI) and cholesterol in BHS female and male subjects (N=229) and found evidence for a modifying effect of a subset of variants on the relationship between cholesterol and BMI (P<0.01). These findings suggest a novel association of gene variants within EPHX2 to susceptibility to AN and provide a foundation for future study of this important yet poorly understood condition
Observation of the TeV gamma-ray source MGRO J1908+06 with ARGO-YBJ
The extended gamma ray source MGRO J1908+06, discovered by the Milagro air
shower detector in 2007, has been observed for about 4 years by the ARGO-YBJ
experiment at TeV energies, with a statistical significance of 6.2 standard
deviations. The peak of the signal is found at a position consistent with the
pulsar PSR J1907+0602. Parametrizing the source shape with a two-dimensional
Gauss function we estimate an extension \sigma = 0.49 \pm 0.22 degrees,
consistent with a previous measurement by the Cherenkov Array H.E.S.S.. The
observed energy spectrum is dN/dE = 6.1 \pm 1.4 \times 10^-13 (E/4 TeV)^{-2.54
\pm 0.36} photons cm^-2 s^-1 TeV^-1, in the energy range 1-20 TeV. The measured
gamma ray flux is consistent with the results of the Milagro detector, but is
2-3 times larger than the flux previously derived by H.E.S.S. at energies of a
few TeV. The continuity of the Milagro and ARGO-YBJ observations and the stable
excess rate observed by ARGO-YBJ along 4 years of data taking support the
identification of MGRO J1908+06 as the steady powerful TeV pulsar wind nebula
of PSR J1907+0602, with an integrated luminosity above 1 TeV about 1.8 times
the Crab Nebula luminosity.Comment: 6 pages, accepted for pubblication by ApJ. Replaced to correct the
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