New divisors in the boundary of the instanton moduli space

Let ${\mathcal I}(n)$ denote the moduli space of rank $2$ instanton bundles of charge $n$ on ${\mathbb P}^3$. It is known that ${\mathcal I}(n)$ is an irreducible, nonsingular and affine variety of dimension $8n-3$. Since every rank $2$ instanton bundle on ${\mathbb P}^3$ is stable, we may regard ${\mathcal I}(n)$ as an open subset of the projective Gieseker-Maruyama moduli scheme ${\mathcal M}(n)$ of rank $2$ semistable torsion free sheaves $F$ on ${\mathbb P}^3$ with Chern classes $c_1=c_3=0$ and $c_2=n$, and consider the closure $\overline{{\mathcal I}(n)}$ of ${\mathcal I}(n)$ in ${\mathcal M}(n)$. We construct some of the irreducible components of dimension $8n-4$ of the boundary $\partial{\mathcal I}(n):=\overline{{\mathcal I}(n)}\setminus{\mathcal I}(n)$. These components generically lie in the smooth locus of ${\mathcal M}(n)$ and consist of rank $2$ torsion free instanton sheaves with singularities along rational curves

Irreducible components of the moduli space of rank 2 sheaves of odd determinant on the projective space

We describe new irreducible components of the moduli space of rank $2$ semistable torsion free sheaves on the three-dimensional projective space whose generic point corresponds to non-locally free sheaves whose singular locus is either 0-dimensional or consists of a line plus disjoint points. In particular, we prove that the moduli spaces of semistable sheaves with Chern classes $(c_1,c_2,c_3)=(-1,2n,0)$ and $(c_1,c_2,c_3)=(0,n,0)$ always contain at least one rational irreducible component. As an application, we prove that the number of such components grows as the second Chern class grows, and compute the exact number of irreducible components of the moduli spaces of rank 2 semistable torsion free sheaves with Chern classes $(c_1,c_2,c_3)=(-1,2,m)$ for all possible values for $m$; all components turn out to be rational. Furthermore, we also prove that these moduli spaces are connected, showing that some of sheaves here considered are smoothable

Measurement of the 0.511 MeV gamma ray line from the Galactic Center

The detection of the 0.511 MeV electron positron annihilation line coming from the Galactic Center to provide the means to estimate the rate of positron production and to test some theoretical sources of positrons is addressed. The results of the measurements of the 0.511 MeV line flux made with a gamma ray experiment on board a stratospheric balloon are presented. The detector field of view looked at the galactic longitude range -31 deg l(II) +41 deg. The observed flux is 0.0067 (+ or - 0.0005) photons 1/cm(2)5 which is in very good agreement with the expected flux when assuming that the Galactic Center is a line source emitting uniformly

GEOTECHNICAL AND CHEMICAL STUDY AND ANALYSIS OF THE MARBLE QUARRY IN THE ALENTEJO AREA, PORTUGAL

This work is a part of an economic project where the knowledge of the surface layers morphology and composed phases identification is essential for the control of any industrial process. In order to improve and increase the production, the quality and the quantity of a marble industry chain. A detailed study of the filling materials of the quarry aimed of this work has been carried out using a different, innovative, and economic methodology. With the intention to determine the nature, composition, and quality of the marble in the quarry of the Alentejo area, we proceed to many physical, mechanical tests, structural and chemical analysis. This work will be divided into two major parts which concern: i) the geotechnical study and ii) the structural and chemical analysis of the marble collect in the quarry. Geological observation and geotechnical study [1, 2] allowed us to determine the geological nature (color, size shape, and hardness),physical (mass, porosity, density and saturation coefficient) and mechanical properties (strength, impact and wear resistance tests). Chemical part [3, 4], consists in the determination of the constitution of the material including phases and elemental composition. Hence, the characterization of the material will be carried out using X-ray diffraction, X-ray fluorescence (XRF), and Energy dispersive Spectrometer (EDS). When, morphology, distribution of the formed phases and structural defects will be determined by mean of the electronic scanning microscope. This work is a part of the project "Quality Control of Ornamental Stone Blocks" with the reference ALT20-03-0247- FEDER-017659 BRO.Project "Quality Control of Ornamental Stone Blocks" with the reference ALT20-03-0247- FEDER-017659 BRO and ICT-ref a UIDB/0468

Biologia, visitantes florais e potencial melífero de Tapirira guianensis (Anacardiaceae) na Amazônia Oriental.

Tapirira guianensis Aubl. é uma espécie arbórea, dioica, abundante nas florestas secundárias da Amazônia Oriental. Foram investigadas a biologia floral e a abundância e a riqueza dos visitantes florais, buscando informações para evidenciar o caráter generalista e a influência do tamanho dos insetos na visitação e no potencial melífero da espécie. O estudo foi realizado no Campus Experimental da Embrapa Amazônia Oriental, em Belém- PA, Brasil. Foram analisadas a fenologia e a morfologia floral, e realizados o teste de receptividade estigmática e as medições do volume e concentração de néctar, além da coleta e da identificação de visitantes florais. T. guianensis possui alta receptividade de estigma, ficando exposta aos visitantes por seis dias. Possui néctar com concentrações médias de açúcares nas flores estaminadas e pistiladas de 36,05 e 13,75% e volumes médios de 1,07 e 1,68 μL/flor, respectivamente. O volume do néctar por flor é considerado alto quando comparado ao de outras espécies de Anacardiaceae e sua concentração média é apreciada pelas abelhas. As ordens Hymenoptera, Hemiptera e Diptera apresentaram maior abundância, destacando-se a família Apidae com maior riqueza. O mais abundante visitante e potencial polinizador foi Trigona williana, em decorrência da presença de um ninho próximo aos indivíduos estudados; no entanto, esse fenômeno necessitará de futuros estudos para avaliar o nível de interferência da proximidade de ninhos naturais na visitação das plantas. T. guianensis é uma espécie primariamente melitófila, com recursos disponíveis para atrair uma grande diversidade de visitantes pequenos e generalistas, que poderão contribuir com a polinização

New moduli components of rank 2 bundles on projective space

We present a new family of monads whose cohomology is a stable rank two vector bundle on $\mathbb{P}^3$. We also study the irreducibility and smoothness together with a geometrical description of some of these families. These facts are used to construct a new infinite series of rational moduli components of stable rank two vector bundles with trivial determinant and growing second Chern class. We also prove that the moduli space of stable rank two vector bundles with trivial determinant and second Chern class equal to 5 has exactly three irreducible rational components

Phosphatidylinositol 3-kinase pathway genomic alterations in 60,991 diverse solid tumors informs targeted therapy opportunities.

BackgroundThe phosphatidylinositol 3-kinase (PI3K) pathway is frequently altered in cancer. This report describes the landscape of PI3K alterations in solid tumors as well as co-alterations serving as potential resistance/attenuation mechanisms.MethodsConsecutive samples were analyzed in a commercial Clinical Laboratory Improvement Amendment-certified laboratory using comprehensive genomic profiling performed by next-generation sequencing (315 genes). The co-alterations evaluated included the Erb-B2 receptor tyrosine kinase 2 (ERBB2), ERBB3, ERBB4, RAS, MET proto-oncogene tyrosine kinase (MET), and mitogen-activated protein kinase kinase (MAP2K) genes as well as tumor protein 53 (TP53), estrogen receptor 1 (ESR1), and androgen receptor (AR).ResultsAlterations in any of 18 PI3K-pathway associated genes were identified in 44% of 60,991 tumors. Although single base and insertions/deletions (indels) were the most frequent alterations, copy number changes and rearrangements were identified in 11% and 0.9% of patients, respectively. Overall, the most frequently altered genes were PIK3 catalytic subunit α (PIK3CA) (13%), phosphatase and tensin homolog (PTEN) (9%), and serine/threonine kinase 11 (STK11) (5%). Tumor types that frequently harbored at least 1 PI3K alteration were uterine (77%), cervical (62%), anal (59%), and breast (58%) cancers. Alterations also were discerned frequently in tumors with carcinosarcoma (89%) and squamous cell carcinoma (62%) histologies. Tumors with a greater likelihood of co-occurring PI3K pathway and MAPK pathway alterations included colorectal cancers (odds ratio [OR], 1.64; P < .001), mesotheliomas (OR, 2.67; P = .024), anal cancers (OR, 1.98; P = .03), and nonsquamous head and neck cancers (OR, 2.03; P = .019). The co-occurrence of ESR1 and/or AR alterations with PI3K alterations was statistically significant in bladder, colorectal, uterine, prostate, and unknown primary cancers.ConclusionsComprehensive genomic profiling reveals altered PI3K-related genes in 44% of solid malignancies, including rare disease and histology types. The frequency of alterations and the co-occurrence of resistance pathways vary by tumor type, directly affecting opportunities for targeted therapy

Magnetic properties of Fe3O4 nanoparticles coated with oleic and dodecanoic acids

Magnetic nanoparticles (NP) of magnetite (Fe3O4) coated with oleic acid (OA) and dodecanoic acid (DA) were synthesized and investigated through Transmission Electron Microscopy (TEM),magnetization M, and ac magnetic susceptibility measurements. The OA coated samples were produced with different magnetic concentrations (78, 76, and 65%) and the DA sample with 63% of Fe3O4. Images from TEM indicate that the NP have a nearly spherical geometry and mean diameter ~ 5.5 nm. Magnetization measurements, performed in zero field cooled (ZFC) and field cooled (FC) processes under different external magnetic fields H, exhibited a maximum at a given temperature TB in the ZFC curves, which depends on the NP coating (OA or DA), magnetite concentration, and H. The temperature TB decreases monotonically with increasing H and, for a given H, the increase in the magnetite concentration results in an increase of TB. The observed behavior is related to the dipolar interaction (DI) between NP which seems to be an important mechanism in all samples studied. This is supported by the results of the ac magnetic susceptibility Xac measurements, where the temperature in which X' peaks for different frequencies follows the Vogel-Fulcher model, a feature commonly found in systems with dipolar interactions. Curves of H vs. TB/TB(H=0) for samples with different coatings and magnetite concentrations collapse into a universal curve, indicating that the qualitative magnetic behavior of the samples may be described by the NP themselves, instead of the coating or the strength of the dipolar interaction. Below TB, M vs. H curves show a coercive field (HC) that increases monotonically with decreasing temperature. The saturation magnetization (MS) follows the Bloch's law and values of MS at room temperature as high as 78 emu/g were estimated, a result corresponding to ~80% of the bulk value. The overlap of M/MS vs. H/T curves for a given sample and the low HC at high temperatures suggest superparamagnetic behavior in all samples studied. The overlap of M/MS vs. H curves at constant temperature for different samples indicates that the NP magnetization behavior is preserved, independently of the coating and magnetite concentration.Comment: 8 pages and 9 figure