Pinning forces of sliding drops at defects

Wetting of surfaces depends critically on defects which alter the shape of the drop. However, no experimental verification of forces owing to the three phase contact line deformation at single defects is available. We imaged the contact line of sliding drops on hydrophobic surfaces by video microscopy. From the deformation of the contact line, we calculate the force acting on a sliding drop using an equation going back to Joanny and de Gennes (J. Chem. Phys., 81 (1984) 554). The calculated forces quantitatively agree with directly measured forces acting between model defects and water drops. In addition, both forces quantitatively match with the force calculated by contact angle differences between the defect and the surface. The quantitative agreement even holds for defects reaching a size of $40\%$ of the drop diameter. Our validation for drop’s pinning forces at single defects is an important step towards a general understanding of contact line motion on heterogeneous surfaces

Rainfall impacts on suspended sediment concentrations in an urbanized tidal creek, southeastern North Carolina

Elevated suspended sediment concentrations in fluvial systems are deleterious to fluvial ecosystems. In these systems, increases in total suspended solids (TSS) following rain events have been well documented. The impacts of rainfall on marsh surface sediments have received less attention. This study examined the relationship between rainfall and TSS in a tidal creek adjacent to upland and marsh surfaces. TSS concentrations were measured for two locations in Bradley Creek in southeastern North Carolina; one tidal site and one non-tidal, headwater site. TSS concentrations at the tidal site were significantly higher during the growing season than during the non-growing season. The headwater site showed no significant change in TSS seasonally. No significant difference in TSS concentrations was found between spring and neap tides. During fair weather at the tidal site, flood tide TSS concentrations were greater than ebb tide TSS concentrations, which were greater than low tide TSS concentrations. Mean fair weather TSS concentrations at the headwater site were 1.0 mg L-1. TSS concentrations increased to 11.9 mg L-1 following rain events. At the tidal site, mean fair weather TSS concentrations were 10.9 mg L-1 at ebb tide, 7.9 mg L-1 at low tide, and 13.5 mg L-1 at flood tide. At the tidal site, mean TSS concentrations following rain events increased to 22.5 mg L-1 at ebb tide, 21.8 mg L-1 at low tide, and 20.9 mg L-1 at flood tide. These data suggest that following rain events in Bradley Creek, upland runoff has a greater impact on increasing TSS than does runoff from the marsh surface. It is not believed that a significant amount of sediment is removed from the marsh during low tide rain events

Small oscillations and the Heisenberg Lie algebra

The Adler Kostant Symes [A-K-S] scheme is used to describe mechanical systems for quadratic Hamiltonians of $\mathbb R^{2n}$ on coadjoint orbits of the Heisenberg Lie group. The coadjoint orbits are realized in a solvable Lie algebra $\mathfrak g$ that admits an ad-invariant metric. Its quadratic induces the Hamiltonian on the orbits, whose Hamiltonian system is equivalent to that one on $\mathbb R^{2n}$. This system is a Lax pair equation whose solution can be computed with help of the Adjoint representation. For a certain class of functions, the Poisson commutativity on the coadjoint orbits in $\mathfrak g$ is related to the commutativity of a family of derivations of the 2n+1-dimensional Heisenberg Lie algebra $\mathfrak h_n$. Therefore the complete integrability is related to the existence of an n-dimensional abelian subalgebra of certain derivations in $\mathfrak h_n$. For instance, the motion of n-uncoupled harmonic oscillators near an equilibrium position can be described with this setting.Comment: 17 pages, it contains a theory about small oscillations in terms of the AKS schem

CD44 isoforms are heterogeneously expressed in breast cancer and correlate with tumor subtypes and cancer stem cell markers

<p>Abstract</p> <p>Background</p> <p>The CD44 cell adhesion molecule is aberrantly expressed in many breast tumors and has been implicated in the metastatic process as well as in the putative cancer stem cell (CSC) compartment. We aimed to investigate potential associations between alternatively spliced isoforms of CD44 and CSCs as well as to various breast cancer biomarkers and molecular subtypes.</p> <p>Methods</p> <p>We used q-RT-PCR and exon-exon spanning assays to analyze the expression of four alternatively spliced CD44 isoforms as well as the total expression of CD44 in 187 breast tumors and 13 cell lines. ALDH1 protein expression was determined by IHC on TMA.</p> <p>Results</p> <p>Breast cancer cell lines showed a heterogeneous expression pattern of the CD44 isoforms, which shifted considerably when cells were grown as mammospheres. Tumors characterized as positive for the CD44⁺/CD24<it>^-</it>phenotype by immunohistochemistry were associated to all isoforms except the CD44 standard (CD44S) isoform, which lacks all variant exons. Conversely, tumors with strong expression of the CSC marker ALDH1 had elevated expression of CD44S. A high expression of the CD44v2-v10 isoform, which retain all variant exons, was correlated to positive steroid receptor status, low proliferation and luminal A subtype. The CD44v3-v10 isoform showed similar correlations, while high expression of CD44v8-v10 was correlated to positive EGFR, negative/low HER2 status and basal-like subtype. High expression of CD44S was associated with strong HER2 staining and also a subgroup of basal-like tumors. Unsupervised hierarchical cluster analysis of CD44 isoform expression data divided tumors into four main clusters, which showed significant correlations to molecular subtypes and differences in 10-year overall survival.</p> <p>Conclusions</p> <p>We demonstrate that individual CD44 isoforms can be associated to different breast cancer subtypes and clinical markers such as HER2, ER and PgR, which suggests involvement of CD44 splice variants in specific oncogenic signaling pathways. Efforts to link CD44 to CSCs and tumor progression should consider the expression of various CD44 isoforms.</p

Malleability of the cortical hand map following a finger nerve block

Electrophysiological studies in monkeys show that finger amputation triggers local remapping within the deprived primary somatosensory cortex (S1). Human neuroimaging research, however, shows persistent S1 representation of the missing hand\u27s fingers, even decades after amputation. Here, we explore whether this apparent contradiction stems from underestimating the distributed peripheral and central representation of fingers in the hand map. Using pharmacological single-finger nerve block and 7-tesla neuroimaging, we first replicated previous accounts (electrophysiological and other) of local S1 remapping. Local blocking also triggered activity changes to nonblocked fingers across the entire hand area. Using methods exploiting interfinger representational overlap, however, we also show that the blocked finger representation remained persistent despite input loss. Computational modeling suggests that both local stability and global reorganization are driven by distributed processing underlying the topographic map, combined with homeostatic mechanisms. Our findings reveal complex interfinger representational features that play a key role in brain (re)organization, beyond (re)mapping

Recurrent gross mutations of the PTEN tumor suppressor gene in breast cancers with deficient DSB repair

Basal-like breast cancer (BBC) is a subtype of breast cancer with poor prognosis. Inherited mutations of BRCA1, a cancer susceptibility gene involved in double-strand DNA break (DSB) repair, lead to breast cancers that are nearly always of the BBC subtype; however, the precise molecular lesions and oncogenic consequences of BRCA1 dysfunction are poorly understood. Here we show that heterozygous inactivation of the tumor suppressor gene Pten leads to the formation of basal-like mammary tumors in mice, and that loss of PTEN expression is significantly associated with the BBC subtype in human sporadic and BRCA1-associated hereditary breast cancers. In addition, we identify frequent gross PTEN mutations, involving intragenic chromosome breaks, inversions, deletions and micro copy number aberrations, specifically in BRCA1-deficient tumors. These data provide an example of a specific and recurrent oncogenic consequence of BRCA1-dependent dysfunction in DNA repair and provide insight into the pathogenesis of BBC with therapeutic implications. These findings also argue that obtaining an accurate census of genes mutated in cancer will require a systematic examination for gross gene rearrangements, particularly in tumors with deficient DSB repair

Malleability of the cortical hand map following a finger nerve block

Electrophysiological studies in monkeys show that finger amputation triggers local remapping within the deprived primary somatosensory cortex (S1). Human neuroimaging research, however, shows persistent S1 representation of the missing hand's fingers, even decades after amputation. Here, we explore whether this apparent contradiction stems from underestimating the distributed peripheral and central representation of fingers in the hand map. Using pharmacological single-finger nerve block and 7-tesla neuroimaging, we first replicated previous accounts (electrophysiological and other) of local S1 remapping. Local blocking also triggered activity changes to nonblocked fingers across the entire hand area. Using methods exploiting interfinger representational overlap, however, we also show that the blocked finger representation remained persistent despite input loss. Computational modeling suggests that both local stability and global reorganization are driven by distributed processing underlying the topographic map, combined with homeostatic mechanisms. Our findings reveal complex interfinger representational features that play a key role in brain (re)organization, beyond (re)mapping

El turismo rural como alternativa para el desarrollo en el norte de la provincia de Córdoba

Ponencia presentada en las VIII Jornadas Interdisciplinarias de Estudios Agrarios y Agroindustriales. Buenos Aires, 31 de octubre al 1 de noviembre de 2013El Turismo rural es una actividad que para los productores de tipo familiar se constituye en una alternativa, en un componente más de una estrategia de desarrollo local, orientada a la diversificación de actividades sustentables en el territorio. En el norte de la provincia de Córdoba se llevan a cabo tres experiencias de este tipo promovidas por organismos estatales. Debido a que el turismo es una actividad que implica numerosas dimensiones de análisis de los distintos ámbitos de la realidad, este trabajo desarrolla un marco conceptual específico basado en la teoría de sistema. Orienta la investigación la siguiente pregunta: Existen similitudes en los procesos de generación de productos turísticos entre las experiencias de turismo rural apoyadas por el Estado en el norte de la provincia de Córdoba, es la pregunta central. La metodología de investigación se inscribe como estudio de casos. Como principal conclusión surge que las experiencias presentan un estadio inicial, concentrándose en los subsistemas, es decir, en las unidades de servicios que componen el sistema y que las propuestas de comunicación con el macro sistema a los fines de captación de visitantes son muy limitadasFil: Ferrer, Guillermo. Universidad Nacional de Córdoba. Facultad de Ciencias Agropecuarias. Departamento de Desarrollo Rural; Argentina.Fil: Barrientos, Mario Alberto. Universidad Nacional de Córdoba. Facultad de Ciencias Agropecuarias. Departamento de Desarrollo Rural; Argentina.Fil: Saal, Gabriel Alberto. Universidad Nacional de Córdoba. Facultad de Ciencias Agropecuarias. Departamento de Desarrollo Rural; Argentina.Fil: Mir, A. B. Universidad Nacional de Córdoba. Centro de Estudios Avanzados. Maestría en Políticas y Gestión del Desarrollo Local; Argentina