Surface tension, surface energy, and chemical potential due to their difference.

It is well-known that surface tension and surface energy are distinct quantities for solids. Each can be regarded as a thermodynamic property related first by Shuttleworth. Mullins and others have suggested that the difference between surface tension and surface energy cannot be sustained and that the two will approach each other over time. In this work we show that in a single-component system where changes in elastic energy can be neglected, the chemical potential difference between the surface and bulk is proportional to the difference between surface tension and surface energy. By further assuming that mass transfer is driven by this chemical potential difference, we establish a model for the kinetics by which mass transfer removes the difference between surface tension and surface energy.

[Implementation of the German Guideline for the Prevention, Diagnosis, Treatment, and Follow-up of Lung Cancer in the Federal State of Berlin]. / Umsetzung der S3-Leitlinie zur Prävention, Diagnostik, Therapie und Nachsorge des Lungenkarzinoms im Land Berlin.

BACKGROUND: In February 2010, the German guideline for the Prevention, Diagnosis and Treatment of Lung Cancer has been published. For the first time in Germany, the implementation of relevant guideline recommendations has been assessed in the federal state of Berlin. METHODS: Based on the quality indicators of the guideline, a questionnaire was designed which aimed at the application of selected diagnostic and therapeutic concepts. This questionnaire was sent out to all outpatient and inpatient units in the federal state of Berlin being presumably involved in lung cancer care. RESULTS: Overall response rate was good (39.8 %), especially from the addressed inpatient units. Inpatient pneumology units showed the highest application rates of guideline recommendations, followed by oncology units. CONCLUSIONS: Taking the methodologically reduced significance of a survey design into account, this study determined a negative trend of decreasing guideline implementation in units with a lesser grade of specialisation in terms of lung cancer care.

Morning and evening circadian oscillations in the suprachiasmatic nucleus in vitro.

Daily biological rhythms are governed by an innate timekeeping mechanism, or 'circadian clock'. In mammals, a clock in the suprachiasmatic nucleus (SCN) comprises multiple autonomous single-cell oscillators, but it is unclear how SCN cells interact to form a tissue with coherent metabolic and electrical rhythms that might account for circadian animal behaviors. Here we demonstrate that the circadian rhythm of SCN electrophysiological activity, recorded as a single daytime peak in hamster hypothalamic coronal slices, shows two distinct peaks when slices are cut in the horizontal plane. Substantiating an idea initially derived from behavioral observations, the properties of these two peaks indicate functional organization of SCN tissue as a clock with two oscillating components.

Double-walled carbon nanotubes under hydrostatic pressure: Raman experiments and simulations.

We have used Raman spectroscopy to study the behavior of double-walled carbon nanotubes (DWNT) under hydrostatic pressure. We find that the rate of change of the tangential mode frequency with pressure is higher for the sample with traces of polymer compared to the pristine sample. We have performed classical molecular dynamics simulations to study the collapse of single (SWNT) and double-walled carbon nanotube bundles under hydrostatic pressure. The collapse pressure (pc) was found to vary as 1/R3, where R is the SWNT radius or the DWNT effective radius. The bundles showed approximately 30% hysteresis and the hexagonally close packed lattice was completely restored on decompression. The pc of a DWNT bundle was found to be close to the sum of its values for the inner and the outer tubes considered separately as SWNT bundles, demonstrating that the inner tube supports the outer tube and that the effective bending stiffness of DWNT, D(DWNT) - 2D(SWNT).

Resonance Raman spectroscopy characterization of single-wall carbon nanotube separation by their metallicity and diameter.

Several techniques were recently reported for the bulk separation of metallic (M) and semiconducting (S) single wall carbon nanotubes (SWNTs), using optical absorption and resonance Raman spectroscopy (RRS) as a proof of the separation. In the present work, we develop a method for the quantitative evaluation of the M to S separation ratio, and also for the SWNT diameter selectivity of the separation process, based on RRS. The relative changes in the integrated intensities of the radial-breathing mode (RBM) features, with respect to the starting material, yield the diameter probability distribution functions for M and S SWNTs in the separated fractions, accounting for the different resonance conditions of individual SWNTs, while the diameter distribution of the starting material is obtained following the fitting procedure developed by Kuzmany and coworkers. Features other than the RBM are generally less effective for characterization of the separation process for SWNTs.

Thyroxine-induced alterations in the testis and seminal vesicles of air-breathing catfish, Clarias gariepinus.

Effect of experimentally induced thyroxine overdose on the testis and seminal vesicles was studied in the air-breathing catfish, Clarias gariepinus during the preparatory and the pre-spawning phase. The present study revealed a marked reduction in testosterone level in serum, testis and seminal vesicles (SV). Histological examination showed a considerable reduction in the number of spermatozoa/spermatids in the seminiferous tubular lumen as well as depletion of fluid in the loculi of SV. SDS-PAGE analysis of SV fluid proteins demonstrated a significant decrease in the level of a ~27 kDa protein in thyroxine treated fishes. Evidences are presented here to indicate that thyroid hormone plays a role in regulating testis and SV function in catfish.

Pineal rhythms are synchronized to light-dark cycles in congenitally anophthalmic mutant rats.

Genetically mutant anophthalmic rats lacking a complete visual system due to the absence of eyeballs and optic nerves up to the optic chiasma were used as a model to study photo-regulated physiological activities. The photoreception in these mutant rats was determined by measuring the neuroendocrine response of the pineal gland-melatonin levels in the serum, and synaptic ribbon complexes (SRCs) in the pinealocytes. These parameters were studied in both normal and anophthalmic rats maintained under light-dark (LD 12:12), continuous dark (DD) and light (LL) conditions. Both normal and mutant anophthalmic animals showed nocturnal increases in serum melatonin levels and in the number and diameter of SRC and their vesicles in the pinealocytes in LD. The daily rhythms persisted even upon transfer to DD both in normal and mutant rats, whereas in LL, the nocturnal elevation of both the parameters disappeared. These observations suggested that congenitally blind rats can perceive light. The studies of these parameters in both normal and mutant rats in reversed-LD conditions confirmed that pineal rhythms can be entrained by light-dark cycles in congenitally anophthalmic mutant rats through a nonvisual system for light perception.

Neuronal maps of the frontal ganglion of the cockroach, Periplaneta americana, prepared by heavy metal iontophoresis.

Neurons in whole mount preparations of the frontal ganglion (FG) of the cockroach, Periplaneta americana, were mapped with the aid of cobalt chloride staining and silver intensification techniques. Eighty-six neurons were counted in the FG after staining with reduced methylene blue. The cell size ranged between 20 to 35 microns in diameter. Of the somata located in the FG, 44 were found to contribute their fibers to the nervus recurrens, 26 to the right frontal commissure, 28 to the left frontal commissure, and 6 to the nervus connectivus. In addition, a few neurons presumably from the tritocerebral region also contribute their fibers in the formation of nervus connectivus. The present study has helped delineate the neuronal connections of the FG with the brain and neuroendocrine system (corpora cardiaca and corpora allata). This information will be useful in facilitating the positioning of microelectrodes in our future electrophysiological experiments.

Design of biomimetic fibrillar interfaces: 2. Mechanics of enhanced adhesion.

This study addresses the strength and toughness of generic fibrillar structures. We show that the stress sigmac required to pull a fibril out of adhesive contact with a substrate has the form sigma(c) = sigma(0)Phi(chi). In this equation, sigma(0) is the interfacial strength, Phi(chi) is a dimensionless function satisfying 0 > 1, but is flaw insensitive for chi < 1. The important parameter chi also controls the stability of a homogeneously deformed non-fibrillar (flat) interface. Using these results, we show that the work to fail a unit area of fibrillar surface can be much higher than the intrinsic work of adhesion for a flat interface of the same material. In addition, we show that cross-sectional fibril dimensions control the pull-off force, which increases with decreasing fibril radius. Finally, an increase in fibril length is shown to increase the work necessary to separate a fibrillar interface. Besides our calculations involving a single fibril, we study the concept of equal load sharing (ELS) for a perfect interface containing many fibrils. We obtain the practical work of adhesion for an idealized fibrillated interface under equal load sharing. We then analyse the peeling of a fibrillar surface from a rigid substrate and establish a criterion for ELS.

Approximating maximum clique with a Hopfield network.

In a graph, a clique is a set of vertices such that every pair is connected by an edge. MAX-CLIQUE is the optimization problem of finding the largest clique in a given graph and is NP-hard, even to approximate well. Several real-world and theory problems can be modeled as MAX-CLIQUE. In this paper, we efficiently approximate MAX-CLIQUE in a special case of the Hopfield network whose stable states are maximal cliques. We present several energy-descent optimizing dynamics; both discrete (deterministic and stochastic) and continuous. One of these emulates, as special cases, two well-known greedy algorithms for approximating MAX-CLIQUE. We report on detailed empirical comparisons on random graphs and on harder ones. Mean-field annealing, an efficient approximation to simulated annealing, and a stochastic dynamics are the narrow but clear winners. All dynamics approximate much better than one which emulates a "naive" greedy heuristic.

Energy function-based approaches to graph coloring.

We describe an approach to optimization based on a multiple-restart quasi-Hopfield network where the only problem-specific knowledge is embedded in the energy function that the algorithm tries to minimize. We apply this method to three different variants of the graph coloring problem: the minimum coloring problem, the spanning subgraph k-coloring problem, and the induced subgraph k-coloring problem. Though Hopfield networks have been applied in the past to the minimum coloring problem, our encoding is more natural and compact than almost all previous ones. In particular, we use k-state neurons while almost all previous approaches use binary neurons. This reduces the number of connections in the network from (Nk)(2) to N(2) asymptotically and also circumvents a problem in earlier approaches, that of multiple colors being assigned to a single vertex. Experimental results show that our approach compares favorably with other algorithms, even nonneural ones specifically developed for the graph coloring problem.

First evaluation of the Joint Clinical Registries of the Coordinating Tumor Center of Berlin.

In the present study, we report the first analysis of the clinical management [corrected] of patients with primary ovarian cancer following the summarized data of the Joint Clinical Registries of the Coordinating Tumor Center of Berlin (Dachverband Tumorzentrum Berlin e.V.). All data were summarized for the period of 2005 to 2008 regarding age, histopathology, time of surgical intervention, follow-up and survival, based on 1124 provided data sets of patients with suspected ovarian tumours. We identified 946 patients with a diagnosis of primary ovarian cancer, mostly of advanced T3 tumour stage (63.7%), FIGO III and IV stage (40.6%) or grade II and III (91%) histology. The median age at time of diagnosis was 61 years (range 15 to 94 years). Most patients (n=414, 69.8%) underwent cytoreductive surgery within one month of diagnosis. The median follow-up period was 26 months; 241 patients died in the analyzed period. The calculated 3-year survival rate was 63.3%, although the median overall survival has not yet been reached. We detected positive correlation of tumour stage (p<0.001) and of FIGO stage (p<0.001) with survival, and these were evaluated as being prognostically significant. The implementation of institutional based clinical registries as part of the modern clinical management of patients with ovarian cancer is feasible and well accepted inside the gynaecological departments of Berlin.

[Introduction of interdisciplinary prostate cancer centers based on the recommendations of the German Cancer Society. A cost-benefit analysis 3 years after accreditation]. / Etablierung von interdisziplinären Prostatakrebszentren nach den Empfehlungen der DKG. Eine Kosten-Nutzen-Analyse 3 Jahre nach Zertifizierung.

The introduction of prostate cancer treatment centers according to the criteria of the German Cancer Society ("Deutsche Krebsgesellschaft", DKG) aims at improving the quality of care for patients with prostate cancer. Systematic analyses of the effects and costs are lacking as yet. Three years after certification of the Interdisciplinary Prostate Cancer Center at the Charité Hospital Berlin we observed a decrease in the rate of positive surgical margins (tumor stage pT2), but other parameters of treatment quality including patient satisfaction remained unchanged. A survey among urologists of the region showed a high acceptance of prostate cancer centers in general. The majority of participating urologists appreciated the work of the Charité center, in particular the treatment recommendations given by the center were mostly followed and the majority of urologists regularly use educational activities of the center. However, only 30% of the participating urologists confirmed short-term improvements in the quality of patient care. Yearly additional costs for the Charité prostate cancer center are estimated at 205,000 euro (precertification phase and certification) and 138,000 euro (monitoring phase), despite the initial drop in mean treatment costs per case (radical prostatectomy). The introduction of prostate cancer treatment centers certified by the DKG is cost intensive, increases in treatment efficiency notwithstanding. Short-term improvements in quality of care cannot be unequivocally demonstrated. Prostate cancer centers serve an important role in counseling and medical education and may thus help disseminate evidence-based treatment strategies.

Deposition and meniscus alignment of DNA-CNT on a substrate.

We present a study of deposition and meniscus alignment of DNA-single walled carbon nanotube hybrids (DNA-CNT) on a silicon wafer coated with an alkyl-silane monolayer. We show that this process occurs in two stages: adsorption of DNA-CNT onto the hydrophobic surface and subsequent alignment by a passing meniscus. We study how pH, ionic strength, and time affect the density of nanotubes deposited on the surface. Experimental results are interpreted using models for the kinetics of deposition and for forces that affect alignment by the meniscus. We show that this method can be used to produce uniform global alignment of controlled density as well as controlled patterns, results that may be useful for applications such as CNT-based device construction.

[Germ cell tumors - documentation of diagnosis and therapy by means of a web-based modular database system]. / Keimzelltumoren - Dokumentation von Diagnostik und Therapie mittels Web-basierten modularen Dokumentationssystems.

PROBLEM: Health telematics is gaining ground worldwide as it promises the bridging of distances in space and time as well as a highly effective use of financial and other resources. In Germany the development and introduction of a national telematic platform is in the foreground at present. However, there are a number of more specialised projects already in existence. The aim of this study was to develop an internet platform to document the quality of individual sections of treatment for patients with germ cell tumours in Berlin and to improve the therapy in conformity with the S2 guidelines. MATERIAL AND METHODS: As a pilot project, a web-based modular database system (WBMDS) was developed, which can be used by any physician involved in the treatment of germ cell tumour patients from any computer connected to the internet. RESULTS: The WBMDS proved to be a practicable system of documentation. Data protection was ensured by pseudonyms as well as symmetrical and asymmetrical coding. The size of the extended documentation mask that had initially seemed to be necessary for valid documentation appeared to be too user-unfriendly with its 833 items. To meet the requirements of the user as well as of the documentation, a compact variant with 496 input fields was designed. On a random basis, treatment not in conformity with the guidelines could be detected in 20 % of 151 patients with the help of this system. CONCLUSION: For the successful use of an oncological database the following showed to be essential:[nl]Queries clearly defined for later statistical evaluation,[nl]clear separation between the phases of planning and implementation,[nl]a size of the database that does not make excessive demands on the user,[nl]intensive training of the users.[nl]The modular database system established proved to be well suitable for a quality-ensuring longitudinal case documentation, which can also be applied to other tumour entities.

Electric fields in an electrolyte solution near a strip of fixed potential.

Electrostatic fields produced by flat electrodes are often used to manipulate particles in solution. To study the field produced by such an electrode, we consider the problem of an infinite strip of width 2a with imposed constant potential immersed in an electrolyte solution. Sufficiently close to the edge of the strip, the solution is determined by classical electrostatics and results in a field singularity. We examine two limiting cases, (a) when strip width a<<1k, the Debye screening length, and (b) when strip width is much greater than the Debye screening length, a>>1k. We present exact results for the two cases in the limit of small potentials where the Poisson-Boltzmann equation can be linearized. By drawing on an analogy with antiplane shear deformations of solids, and by employing the path-independent J integral of solid mechanics, we present a new method for determining the strength of the edge singularity. The strength of the singularity defines an exact near-field solution. In the far field the solution goes to that of a line of charge. The accuracy of the solution is demonstrated by comparison with the numerical solutions of the Poisson-Boltzmann equation using the finite element method.

Rhythmic multiunit neural activity in slices of hamster suprachiasmatic nucleus reflect prior photoperiod.

The suprachiasmatic nucleus (SCN) is an endogenous circadian pacemaker, and SCN neurons exhibit circadian rhythms of electrophysiological activity in vitro. In vivo, the functional state of the pacemaker depends on changes in day length (photoperiod), but it is not known if this property persists in SCN tissue isolated in vitro. To address this issue, we prepared brain slices from hamsters previously entrained to light-dark (LD) cycles of different photoperiods and analyzed rhythms of SCN multiunit neuronal activity using single electrodes. Rhythms in SCN slices from hamsters entrained to 8:16-, 12:12-, and 14:10-h LD cycles were characterized by peak discharge rates relatively higher during subjective day than subjective night. The mean duration of high neuronal activity was photoperiod dependent, compressed in slices from the short (8:16 and 12:12 LD) photoperiods, and decompressed (approximately doubled) in slices from the long (14:10 LD) photoperiod. In slices from all photoperiods, the mean phase of onset of high neuronal activity appeared to be anchored to subjective dawn. Our results show that the electrophysiological activity of the SCN pacemaker depends on day length, extending previous in vivo data, and demonstrate that this capacity is sustained in vitro.

The Role of Viscoelastic Adhesive Contact in the Sintering of Polymeric Particles.

The sintering of polymeric particles is analyzed by considering the growth of contact between viscoelastic spheres driven by adhesive intersurface forces. This process is dominant during the initial phase of sintering and is succeeded by a viscous sintering step that is driven by surface tension and accommodated by viscous flow. The intersurface forces in this work are described by a cohesive zone model. A new formulation of adhesive contact that does not require the cohesive zone to be smaller than the contact radius, together with finite element simulations is used to study the growth of contact. The results of this paper establish conditions that determine the dominant mechanism of contact growth during sintering. These conditions are described using a "deformation map". For a Maxwell material, if particle radius R(max),

An Intersurface Stress Tensor

Distributed forces resulting from molecular interactions between macroscopic bodies are usually concentrated near surfaces. A new formulation has been developed that replaces these distributed body forces by effective surface tractions and is not limited by the geometrical restrictions of Derjaguin's approximation. It offers great computational simplification over the use of the body-force distribution. The body-force distribution is integrated and partitioned to various surface elements. The resulting expressions for surface traction involve a second-order tensor termed the intersurface stress tensor. It is a symmetric tensor defined for any body in terms of the intermolecular potential and the shape of the body. It acts much like the internal stress tensor; the surface traction vector on a surface introduced into its field is the inner product of the tensor and the surface normal. The new surface formulation reduces to Derjaguin's approximation for the case of a half-space with a plane surface. Properties of the new tensor are explored. Actual components are derived for several geometries.

Cell death in exorbital lachrymal gland of anophthalmic mutant rat during postnatal development.

Regression in the exorbital lachrymal gland was observed in congenital blind mutant rats lacking eyeballs and optic nerves. The morphological changes during postnatal development in acinar cells of the lachrymal gland of mutant rats were compared with those of normal rats at day 13 (before the opening of the eyes), day 30 (15 days after opening of the eyes) and the adult (90 days). Atrophy of the lachrymal gland is most likely to be associated with absence of functional signals. During regression, there is a massive elimination of cells from the acini; no fibrosis or immune reaction (lymphocytic infiltration) was observed in the gland. This atrophy in the lachrymal gland of blind rats was not associated with the biochemical markers of apoptosis. Present observations indicate that cell elimination from the lachrymal gland in blind rats is a special type of apoptosis, where cell homeostasis is not required.