Resolved-Sideband Cooling of a Levitated Nanoparticle in the Presence of Laser Phase Noise.

We investigate the influence of laser phase noise heating on resolved sideband cooling in the context of cooling the center-of-mass motion of a levitated nanoparticle in a high-finesse cavity. Although phase noise heating is not a fundamental physical constraint, the regime where it becomes the main limitation in Levitodynamics has so far been unexplored and hence embodies from this point forward the main obstacle in reaching the motional ground state of levitated mesoscopic objects with resolved sideband cooling. We reach minimal center-of-mass temperatures comparable to T_{min}=10  mK at a pressure of p=3×10^{-7}  mbar, solely limited by phase noise.

Unraveling the optomechanical nature of plasmonic trapping.

Noninvasive and ultra-accurate optical manipulation of nanometer objects has recently gained interest as a powerful tool in nanotechnology and biophysics. Self-induced back-action (SIBA) trapping in nano-optical cavities has the unique potential for trapping and manipulating nanometer-sized objects under low optical intensities. However, thus far, the existence of the SIBA effect has been shown only indirectly via its enhanced trapping performances.

Realization of nonequilibrium thermodynamic processes using external colored noise.

We investigate the dynamics of single microparticles immersed in water that are driven out of equilibrium in the presence of an additional external colored noise. As a case study, we trap a single polystyrene particle in water with optical tweezers and apply an external electric field with flat spectrum but a finite bandwidth of the order of kHz. The intensity of the external noise controls the amplitude of the fluctuations of the position of the particle and therefore of its effective temperature.

The basement membrane of the isolated rat colonic mucosa. A light, electron and atomic force microscopy study.

Basement membranes (BM) are structures of the extracellular matrix (ECM), which are involved in epithelial barriers, but also play an important role in processes such as cell adhesion, cell growth and tissue healing. The aim of this study was to investigate possible effects of cell removal on the structure of the BM of the colonic mucosa. The superficial epithelium was removed with EDTA and the samples were then mechanically fixed for immunohistochemistry, TEM, SEM and AFM.

[Experimental corneal imaging and corneal surgery with non-amplified femtosecond laser pulses].

Background: Non-amplified femtosecond laser was used to induce multiphoton effects for corneal tissue imaging and for tissue ablation.

Material And Methods: A non-amplified titanium-sapphire laser was coupled to a laser scanning microscope in order to examine human and porcine cornea. Tissue was subjected to imaging and lesions were created using identical optical pathways at pulse energies below 2 nJ.

Crowding induces differences in the diffusion of thermophilic and mesophilic proteins: a new look at neutron scattering results.

The dynamical basis underlying the increased thermal stability of thermophilic proteins remains uncertain. Here, we challenge the new paradigm established by neutron scattering experiments in solution, in which the adaptation of thermophilic proteins to high temperatures lies in the lower sensitivity of their flexibility to temperature changes. By means of a combination of molecular dynamics and Brownian dynamics simulations, we report a reinterpretation of those experiments and show evidence that under crowding conditions, such as in vivo, thermophilic and homolog mesophilic proteins have diffusional properties with different thermal behavior.

Instabilities of the harmonic oscillator with fluctuating damping.

We investigate the instabilities of a linear damped oscillator due to fluctuations of the damping parameter. The fluctuations are driven either by Gaussian white noise or Poisson white noise (white shot noise). We consider three notions of stability.

Real-time detection of changes in the electrophoretic mobility of a single cell induced by hyperosmotic stress.

Living cells survive environmentally stressful conditions by initiating a stress response. We monitored changes in the electrophoretic mobility (EPM) of single, optically trapped yeast cells under hyperosmotic stress conditions using optical tweezers combined with a position detector. We studied the dynamics of the EPM stress response for cells at different phases of the cell cycle.

The surface topography of the choroid plexus. Environmental, low and high vacuum scanning electron microscopy.

Environmental scanning electron microscopy (ESEM) allows the examination of hydrated and dried specimens without a conductive metal coating which could be advantageous in the imaging of biological and medical objects. The aim of this study was to assess the performance and benefits of wet-mode and low vacuum ESEM in comparison to high vacuum scanning electron microscopy (SEM) using the choroid plexus of chicken embryos as a model, an organ of the brain involved in the formation of cerebrospinal fluid in vertebrates. Specimens were fixed with or without heavy metals and examined directly or after critical point drying with or without metal coating.

Experimental femtosecond laser-assisted nanosurgery of anterior lens capsule.

Purpose: To investigate femtosecond laser-assisted nanosurgery of the anterior lens capsule in a prospective in vitro study.

Methods: Eight anterior lens capsules obtained during conventional phaco surgery were irradiated with a nonamplified 80-MHz near-infrared 800-nm titanium:sapphire femtosecond laser. Line intratissue laser cuts were examined by femtosecond multiphoton laser scanning microscopy (MLSM) and transmission electron microscopy (TEM).

[Femtosecond laser ablation and scanning microscopy of the internal retinal limiting membrane: an experimental study].

The investigation was undertaken to study whether femtosecond laser ablation and microscopy might be used in the internal retinal borderline membrane. Ablation of internal limiting membrane preparations removed using or not using indocyanine green was made by a low-energy femtosecond laser. Examination of the preparations by laser and electron microscopy revealed precision laser cuts of the internal retinal borderline membrane.

The Bionas technology for anticancer drug screening.

Background: The Bionas 2500(®) analyzing system is an advanced label-free technology using a cell-based multi-sensor array, which is commercially available. Data on metabolism, respiration, adhesion, cell proliferation and cell death rates, as well as ligand-receptor interactions (multi-parametric) can be acquired and statistically evaluated. Noteworthy is the possibility of analyzing later after effects and/or recovery after drug treatment.

In vitro femtosecond laser-assisted nanosurgery of porcine posterior capsule.

Purpose: To investigate femtosecond laser-assisted nanosurgery of the posterior capsule in a prospective in vitro animal study.

Setting: Department of Ophthalmology and Eye Hospital, University of Saarland, Homburg, and Fraunhofer Institute for Biomedical Engineering, St. Ingbert, Germany.

Posttraumatic GABA(A)-mediated [Ca2+]i increase is essential for the induction of brain-derived neurotrophic factor-dependent survival of mature central neurons.

A shift of GABA(A)-mediated responses from hyperpolarizing to depolarizing after neuronal injury leads to GABA(A)-mediated increase in [Ca2+](i). In addition, central neurons become dependent on BDNF for survival. Whether these two mechanisms are causally interrelated is an open question.

Resistance of mitochondrial p53 to dominant inhibition.

Background: Mutation of a tumor suppressor allele leaves the second as backup. Not necessarily so with p53. This homo-tetrameric transcription factor can become contaminated with mutant p53 through hetero-tetramerization.

Femtosecond laser-assisted retinal imaging and ablation: experimental pilot study.

Purpose: To investigate retinal imaging and ablation using femtosecond laser pulses.

Materials And Methods: Two non-amplified near-infrared femtosecond lasers were used to irradiate porcine retinal specimens in vitro. The lasers were used for tissue removal as well as multiphoton laser scanning microscopy.

In vitro noncontact intravascular femtosecond laser surgery in models of branch retinal vein occlusion.

Purpose: To investigate intravenous femtosecond laser surgery in models of branch retinal vein occlusion.

Materials And Methods: Non-amplified near infrared femtosecond laser was used to ablate polyamide sutures and human hairs inserted into the vascular lumina of porcine retinal veins in vitro. Specimens were subjected to multiphoton laser scanning microscopy and electron microscopy.

Large bore catheters with surface treatments versus untreated catheters for blood access.

Infection, thrombosis, and stenosis are among the most frequent complications associated with blood contacting catheters. Because these problems are usually related to surface properties of the base catheter material, surface treatment processes, such as ion implantation and ion beam assisted deposition (IBAD) (silver based coatings), can be used to mitigate such complications. Because these ion beam based processes affect only the near-surface region (approximately the outer 1 microm), there is little effect on bulk material properties.

A new method to assess drug sensitivity on breast tumor acute slices preparation.

A method for assessing tumor drug sensitivity is described that is based on preparation of tissue slices and use of silicon chips equipped with electrochemical sensors (multisensor array). The tumor slices (200-300 microM thick) are prepared after surgery and incubated in a medium for recovery after slicing. The advantage, compared to other preparations, is that the original three-dimensional structure is retained.

Adhesion, spreading, and aggregation of platelets in flowing blood and the reliability of the retention test Homburg.

Adhesion and aggregation are important parameters characterizing the function of intact platelets in flowing blood and in contact with a more or less thrombogenic surface. In the retention test Homburg (RTH), platelets are exposed to a standardized textured surface (Sysmex retention tubes) under defined conditions of flow. Platelet counts are performed before and after the Sysmex retention tube passage.

[Platelet retention test Homburg (RTH) and drug monitoring of platelet adhesive properties of von Willebrand factor].

Platelet plug formation is initiated by the process of platelet adhesion, mainly mediated by the von Wille-brand factor (VWF). Therefore, apart from established criteria the platelet adhesion property is a further criterion to determine VWF e. g.

Long-term catheters for apheresis and dialysis with surface treatment with infection resistance and low thrombogenicity.

Infection, thrombosis, and stenosis are among the most frequent complications associated with blood-contacting catheters. These problems are usually related to surface properties of the base catheter material. Surface treatment processes, such as ion implantation and ion beam assisted deposition (IBAD) and microdomain structured surfaces, can be used to mitigate such complications.

Dural cell culture. A new approach to study duraplasty.

Fistulas of the cerebrospinal fluid are often repaired by insertion of grafts of various kinds. However, current knowledge of wound healing after graft insertion is limited, and only a few animal studies are available. The objective of this study is to test whether an in vitro model is suited to analyze cellular healing aspects after duraplasty and to assess dura substitutes in such conditions in regard to their surface attractiveness for cellular migration from the dura margins.

Resveratrol induces colon tumor cell apoptosis independently of p53 and precede by epithelial differentiation, mitochondrial proliferation and membrane potential collapse.

Resveratrol, a polyphenol present in wine and grapes, can inhibit tumor cell growth in vitro and tumorigenesis in vivo. Some of its effects have been linked to activation of the p53 tumor suppressor; however, p53 is frequently mutated in tumors, particularly in the common and often therapy-resistant colon cancers. Using the human wild-type p53-expressing HCT116 colon carcinoma cell line and HCT116 cells with both p53 alleles inactivated by homologous recombination, we show in the current study that resveratrol at concentrations comparable to those found in some foods can induce apoptosis independently of p53.

Endogenous brain-derived neurotrophic factor and neurotrophin-3 antagonistically regulate survival of axotomized corticospinal neurons in vivo.

Neuronal growth factors regulate the survival of neurons by their survival and death-promoting activity on distinct populations of neurons. The neurotrophins nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and neurotrophin-3 (NT-3) promote neuronal survival via tyrosine kinase (Trk) receptors, whereas NGF and BDNF can also induce apoptosis in developing neurons through p75(NTR) receptors in the absence of their respective Trk receptors. Using mutant mice and inactivation of neurotrophins and their receptors with antibodies in rats, we show that endogenous NT-3 induces death of adult BDNF-dependent, axotomized corticospinal neurons (CSNs).