Search results for "OLDS"

Separate processing of “color” and “brightness” in goldfish

1991

Spectral sensitivity was measured under different adaptation levels using a behavioral training technique in which the fish had to discriminate between a dark test field and a test field illuminated with monochromatic light. Depending on which of the two test fields was used as training test field, two functions were obtained which differ (1) in absolute sensitivity and (2) in shape. When trained on the dark test field, the fish seems to discriminate on the basis of a "color" cue, but it uses a "brightness" cue when trained on the illuminated test field. This was concluded from measurements of wavelength discrimination. Under low levels of the adaptation light (1.5 and 0.2 lx instead of 20 …

Markovian Connection, Curvature and Weitzenböck Formula on Riemannian Path Spaces

2001

Abstract We shall consider on a Riemannian path space P m o ( M ) the Cruzeiro–Malliavin's Markovian connection. The Laplace operator will be defined as the divergence of the gradient. We shall compute explicitly the associated curvature tensor. A Weitzenbock formula will be established. To this end, we shall introduce an “inner product” between the tangent processes and simple vector fields.

Graded metrics adapted to splittings

1997

Homogeneous graded metrics over split ℤ2-graded manifolds whose Levi-Civita connection is adapted to a given splitting, in the sense recently introduced by Koszul, are completely described. A subclass of such is singled out by the vanishing of certain components of the graded curvature tensor, a condition that plays a role similar to the closedness of a graded symplectic form in graded symplectic geometry: It amounts to determining a graded metric by the data {g, ω, Δ′}, whereg is a metric tensor onM, ω 0 is a fibered nondegenerate skewsymmetric bilinear form on the Batchelor bundleE → M, and Δ′ is a connection onE satisfying Δ′ω = 0. Odd metrics are also studied under the same criterion an…

Risk stratification for invasive fungal infections in patients with hematological malignancies: SEIFEM recommendations

2016

Invasive fungal infections (IFIs) are an important cause of morbidity and mortality in immunocompromised patients. Patients with hematological malignancies undergoing conventional chemotherapy, autologous or allogeneic hematopoietic stem cell transplantation are considered at high risk, and Aspergillus spp. represents the most frequently isolated micro-organisms. In the last years, attention has also been focused on other rare molds (e.g., Zygomycetes, Fusarium spp.) responsible for devastating clinical manifestations. The extensive use of antifungal prophylaxis has reduced the infections from yeasts (e.g., candidemia) even though they are still associated with high mortality rates. This pa…

SCAFFOLDS BASED ON HYALURONIC ACID AND POLYAMINOACIDS AS ARTIFICIAL ECM SUBSTITUTES

2009

Biologic response of inguinal hernia prosthetics: a comparative study of conventional static meshes versus 3D dynamic implants.

2015

Despite improvements in prosthetics and surgical techniques, the rate of complications following inguinal hernia repair remains high. Among these, discomfort and chronic pain have become a source of increasing concern among surgeons. Poor quality of tissue ingrowth, such as thin scar plates or shrinking scars-typical results with conventional static implants and plugs-may contribute to these adverse events. Recently, a new type of 3D dynamically responsive implant was introduced to the market. This device, designed to be placed fixation-free, seems to induce ingrowth of viable and structured tissue instead of regressive fibrotic scarring. To elucidate the differences in biologic response be…

Silk fibroin scaffolds enhance cell commitment of adult rat cardiac progenitor cells.

2015

The use of three-dimensional (3D) cultures may induce cardiac progenitor cells to synthesize their own extracellular matrix (ECM) and sarcomeric proteins to initiate cardiac differentiation. 3D cultures grown on synthetic scaffolds may favour the implantation and survival of stem cells for cell therapy when pharmacological therapies are not efficient in curing cardiovascular diseases and when organ transplantation remains the only treatment able to rescue the patient’s life. Silk fibroin-based scaffolds may be used to increase cell affinity to biomaterials and may be chemically modified to improve cell adhesion. In the present study, porous, partially orientated and electrospun nanometric n…

Porous biomaterials and scaffolds for tissue engineering

2019

In the present article, an overview of the definition of tissue engineering and scaffold requirements is reported. In particular, scaffold porosity and its relevance for several tissue target regeneration is highlighted. Different scaffold fabrication techniques are reported and explained in details, highlighting advantages and disadvantages for all of these techniques, regarding the specific final applications.

Channeled scaffolds implanted in adult rat brain.

2012

Scaffolds with aligned channels based on acrylate copolymers, which had previously demonstrated good com- patibility with neural progenitor cells were studied as coloniz- able structures both in vitro with neural progenitor cells and in vivo, implanted without cells in two different locations, in the cortical plate of adult rat brains and close to the subven- tricular zone. In vitro, neuroprogenitors colonize the scaffold and differentiate into neurons and glia within its channels. When implanted in vivo immunohistochemical analysis by confocal microscopy for neural and endothelial cells markers demonstrated that the scaffolds maintained continuity with the surrounding neural tissue and wer…

Using Polymeric Scaffolds for Vascular Tissue Engineering

2014

With the high occurrence of cardiovascular disease and increasing numbers of patients requiring vascular access, there is a significant need for small-diameter (<6 mm inner diameter) vascular graft that can provide long-term patency. Despite the technological improvements, restenosis and graft thrombosis continue to hamper the success of the implants. Vascular tissue engineering is a new field that has undergone enormous growth over the last decade and has proposed valid solutions for blood vessels repair. The goal of vascular tissue engineering is to produce neovessels and neoorgan tissue from autologous cells using a biodegradable polymer as a scaffold. The most important advantage of …