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The use of swarms of nanobots to perform seemingly miraculous tasks is a common trope in the annals of science fiction.1 Although several of these remarkable feats are still very much in the realm of fiction, scientists have recently overcome many of the physical challenges associated with operating on the small scale and have generated the first generation of autonomous self-powered nanomotors and pumps. The motors can be directed by chemical and light gradients, pick up and deliver cargo, and exhibit collective behavior.

Powered by UV light, nano/micrometer-sized silver chloride particles exhibit autonomous movement and form "schools" in aqueous solution, i.e. regions in which the number density of particles is significantly higher than the global average. In this paper, the silver chloride particles in such a system are classified by their proximity to other AgCl particles--be they isolated, coupled or schooled--and their motion paths are tracked and analyzed. By plotting time-averaged mean squared displacements of each particle over various time intervals from 0.1 s to 15.0 s, we discover different diffusive behaviors for the three classes of silver chloride particles.

The use of swarms of nanobots to perform seemingly miraculous tasks is a common trope in the annals of science fiction.1 Although several of these remarkable feats are still very much in the realm of fiction, scientists have recently overcome many of the physical challenges associated with operating on the small scale and have generated the first generation of autonomous self-powered nanomotors and pumps. The motors can be directed by chemical and light gradients, pick up and deliver cargo, and exhibit collective behavior.

THIS REVIEW surveys and characterizes papers comprising various fields of heat transfer that were published in the literature during 1992. It is intended to encompass the English language literature, including English translations of foreign language papers, and also includes many foreign language papers for which English abstracts are available. The literature search was inclusive, however, the great number of publications made selections in some of the review sections necessary. Several conferences during 1992 were devoted to heat transfer or included heat transfer topics in their sessions. They will be briefly discussed in chronological order in this section. The International Center for Heat and Mass Transfer was especially active in organizing meetings and Symposia. The Spacio-Temporal Structure and Chaos in Heat and Mass Transfer Processes was discussed in a symposium on 21-24 May in Athens, Greece. A seminar on Imaging in Transport Processes was held in the same town on 25-29 May. Proceedings for ICHM symposia are available at Hemisphere Publishing Corp. or at the Center. The 37th ASME International Gas Turbine and Aeroengine Congress and Exposition (ASME Turbo Expo) contained in its program eight sessions on blade cooling, hot gas path heat transfer, film cooling, and unsteady turbine heat transfer. It was held in Cologne, Germany on l-4 June. Papers presented at the conference are available at the ASME order department. The Second International Conference on Advanced Computational Methods in Heat Transfer -was organized by the Wessex Institute of Technology at Milan, Italy on 7-10 July. Papers are published by Computational Mechanics Publications. The 28th National Heat Transfer Conference and Exhibition on 9-12 August in San Diego, California discussed in general and poster sessions, panel discussions, symposia, and an open forum topics ranging over the whole field of heat transfer and its applications. The 1992 Donald Q. Kern Lecture was held by Hans K. Fauske on “Ptevention and Mitigation of Hazardous Chemical Releases” and the Max Jakob Memorial Award Lecture by Franz Mayinger discussed “Heat Transfer and Bubble Dynamics in NonEquilibrium Two-Phase Flow”. The Max Jakob Medal and the Donald Q. Kern Award were presented to the speakers at a special dinner. Proceedings of the conference am available at the ASME order department or as AIChE title “Heat Transfer”, Volume 88, San Diego, 1992. The International Center for Heat and Mass Transfer organized an International Symposium on Heat Transfer in Turbomachinery together with a poster session on 24-28 August in Athens, Greece. Conference papers are published by Hemisphere Publishing Corporation. The First European ThermalSciences and 3rd UK National Heat Transfer Conference, 16-18 September in Birmingham, U.K. presented papers on boiling and condensation, heat exchangers, natural convection, nuclear reactors, combustion, radiation and chemical reactions, convection, fouling, and heat transfer to and from solids. Invited lectures by M. G. Carvalho, M. Cumo, F. Mayinger, and P. le QuCr6 on numerical methods, high heat flux, compact heat exchangers, and chaos rounded off the program. The ASME Winter Annual Meeting took place in 8-13 November at Anaheim, California. Heat transfer sessions dealt with basic processes and with applications like biological heat transfer, gas turbines, powder processing, fire and combustion, heat pipes, environment, non-CFC refrigeration, super-conduction, thermoplastic composites, materials processing and electronic packaging. Heat Transfer Memorial Awards were presented to Vijay K. Dhir, Wataru Nakayama, and Thomas F. Irvine, Jr. Richard J. Goldstein was made an honorary ASME member. A list of books related to heat transfer and new journals published during 1992 is presented on the following pages. To facilitate the use of the review, a listing of the subject items is made below in the order in which they appear in the text. The letter which appears adjacent to each subject heading is also added to the references cited in each category.

Obesity has become an increasingly serious problem in pediatric and adolescent populations in the United States. Although bariatric surgery has been offered to morbidly obese adolescents for the past several decades, it remains controversial. However, the benefits of weight loss surgery in this population have been realized, particularly its long-term physical and emotional effects on adolescents. This article reviews the demographics and health implications of adolescent obesity, describes the most common adolescent bariatric surgical procedures and their outcomes, discusses the ethical issues involved in elective surgery in this population, and outlines the key components of an adolescent bariatric surgical program.

Based on extensive measurements of energy usage for a variety of building facades, a computer model has been developed for calculating in advance the heating and cooling requirements of test rooms equipped with arbitrary facades. To simplify the predictive calculation, the three-dimensional physical model was transformed to a one-dimensional, linear, computational model. The computer model uses the results of an earlier sensitivity analysis. This permits the precise numerical modeling of the measured results and gives special value to the adaptation of this model for describing the geometric and thermal relations investigated experimentally. The results of the numerical calculations are found to be in good agreement with the measurements for six test rooms. This agreement justifies the linear numerical model and the computer program for predicting the energy flows in different room structures. Further, the computer model not only provides results which follow the course of weather conditions for the test year but yields results as well for a Standard Reference Year for the region.

We have discovered that silver chloride (AgCl) particles in the presence of UV light and dilute hydrogen peroxide exhibit both single-particle and collective oscillations in their motion which arise due to an oscillatory, reversible conversion of AgCl to silver metal at the particle surface. This system exhibits several of the hallmarks of nonlinear oscillatory reactions, including bistability, reaction waves, and synchronized collective oscillations at high particle concentrations. However, unlike traditional oscillatory reactions that take place among dispersed solute species in solution or near a fixed electrode surface, this system of self-mobile catalytic particles evinces a new dynamical length scale: the interparticle spacing, which appears to control wave propagation. The collective motions of these powered nanoparticles self-organize into clumped oscillators with significant spatiotemporal correlations between clumps. A variant of this system using a regular array of lithographically patterned silver disks supports the propagation of binary "On/Off" Ag/AgCl waves through the lattice.

One of the more interesting recent discoveries has been the ability to design nano/ microparticles which catalytically harness the chemical energy in their environments to move autonomously. These "nanomotors" can be directed by externally applied magnetic fields, or optical and chemical gradients. Our group has now developed two systems in which chemical secretions from the translating micro/nanomotors initiate long-range, collective interactions among the particles via self-diffusiophoresis. Herein, we discuss two different approaches to model the complex emergent behavior of these particles, the first being a qualitative probability-based model with wide applicability, and the second being a more quantitative Brownian dynamics simulation specific to the self-diffusiophoretic phenomenon.

In adults, mesenteric venous thrombosis with extension into the portal system is a known complication of total proctocolectomy with pouch ileoanal anastomosis. Although frequently reported in adults, this complication is rare in pediatric patients undergoing this operation. We report 2 cases of adolescent patients with ulcerative colitis who experienced portal vein thrombosis after this procedure. Both were treated with systemic anticoagulation therapy with complete resolution of their clots. We recommend that mesenteric/portal venous thrombosis be considered in the differential diagnosis in any child presenting with fever, abdominal pain, and leukocytosis after restorative proctocolectomy with ileal pouch anastomosis and that imaging obtained to evaluate abdominal complaints in this population be directed toward ruling out this complication.

Background To determine the effect of bovine pericardium strip (BPS) reinforcement of the circular stapler on the gastrojejunostomy leak rates and staple line failure after laparoscopic Roux-en-Y gastric bypass (LRYGB) at a university hospital in the United States. Gastrojejunostomy leak after LRYGB is a devastating complication. Various techniques, including buttressing the gastrojejunostomy staple line with biomaterial, have been used in an effort to minimize leaks. Methods A total of 350 consecutive patients underwent LRYGB without staple line buttressing. After this initial experience, BPS reinforcement of the gastrojejunostomy was conducted in 81 consecutive patients. BPS reinforcement was not used for the final 69 consecutive patients in this 500 patient series. Circular staple line failures (intraoperative immediate and complete failure of the anastomosis) and leaks were evaluated retrospectively. Results Three leaks (and no intraoperative staple line failures) occurred in 419 patients without BPS buttressing, all in the first 100 cases of our experience, and 3 leaks and an anastomotic staple line failure occurred in the 81 patients with BPS buttressing (.7% versus 4.9%, P = .02). The body mass index and other potential leak risk factors did not differ between the 2 groups. Conclusion In our experience, buttressing of the circular staple line with BPS during LRYGB was associated with an increased staple line adverse event rate. BPS buttressing of the gastrointestinal circular staple lines should be used with caution.

Obesity is a major health problem in the United States. The Framingham Heart Study group recently published that the incidence of obesity (BMI >30) in men increased from 5.8 % in the 1950s to 14.8% in the 1990s and the incidence in women has increased from 3.9 to 14% in the 1990s [1]. Obesity is a contributing factor in multiple health conditions including type 2 diabetes mellitus, coronary artery disease, dyslipidemia, stroke, sleep apnea, osteoarthritis, and some cancers. Morbid obesity is not only costly in terms of a patient’s overall quality of life, but also has important financial repercussions. A study of national costs attributed to an overweight body habitus (BMI 25-29.9) and obesity (BMI > 30) projected medical expenses due to these conditions to account for approximately 92.6 billion dollars in 2002 [2, 3].

There are two basic types of legal regime for the protection of geographical indications (GIs). Some systems, notably that of the European Union, define and treat GIs as a distinct type of intellectual property. This approach is also reflected in the provisions concerning GIs in the Agreement on Trade-Related Aspects of Intellectual Property Rights (TRIPS Agreement). Other legal systems, notably those of Australia, Canada and the United States, treat GIs as a subcategory of trademarks. Like trademarks, GIs function principally as a means of providing information to consumers. EU legislation and jurisprudence, however, define GIs more expansively than do trademark-based legal systems, and see GIs as in some ways superior to trademarks. The EU is attempting to incorporate other features of its system of GI protection into the WTO/TRIPS system. But the nature of GIs is somewhat at odds with that of other types of intellectual property.

A semiempirical mathematical model has been developed to predict the permeability of porous alumina over a wide temperature range at atmospherie pressure. Although the thermal expansion of the alumina is of the order of 1 % over the range of temperatures considered, the apparent permeability of the sample to gas flow varies by over 400%. This behavior is due to the dependence of the mean free path of a gas on temperature and to the corresponding slip conditions that occur in the pores of the solid. The model developed correlates the “apparent permeability” data with temperature, true permeability, gas viscosity, and gas molecular weight, variables suggested by kinetie theory on mean free path and slip. Apparent permeability was found to be a very strong function of temperature. It exhibited both a direct thermal dependence and an indirect dependence, manifest through thermally driven variations in the gas viscosity. A mathematical model from the literature was used for gas viscosity. The inverse correlation with gas molecular weight, suggested by kinetie theory, is demonstrated. The model covers the temperature range between 250 and 1600 K. Small molelcule gases including air, nitrogen, argon, and helium were used in the development.

The increase in longevity among patients with cystic fibrosis has brought to light comorbidities associated with the disease that are less acutely fatal than its pulmonary manifestations. Modern retrospective analysis has demonstrated an increased risk of gastrointestinal malignancy in patients with cystic fibrosis, with a marked elevation in malignancy rates among patients in their 20s and 30s. Here we report a case of colonic adenocarcinoma presenting as pneumaturia in a 13-year-old patient with cystic fibrosis.

A novel microfluidic pumping system is presented which consists of spatially defined palladium features on a gold surface and which incorporates either hydrazine or N,N-dimethylhydrazine as fuel. By choosing the appropriate fuel, it is possible to control the direction of pumping.

Detailed geological mapping and structural analysis of the Blankuskopf- and Wildberggroup in the Rätikon area (Vorarlberg/Austria) was carried out in the framework of a Diploma-thesis at the University of Freiburg. The full stratigraphy of the Northen Calcareous Alps (NCA) can be found in the area, starting with the skythian Bundsandstein and continuing up to the upper Cretaceous Kreideschiefer, as well as lithologies from the south-Penninic Arosazone. The structural style of the mapping area is characterized by many folds and thrusts and shows two mean features: 1) From the lower to the higher tectonic unit and from NW to SE there is a change in transport direction from NW via N to NE. This change is linked to a clockwise rotation of each unit with respect to its underlying unit. 2) Within each unit there is a change in transport direction from NW in its western part to N in its eastern part. This is especially pronounced in the well-conserved unit of the Blankuskopfgroup. The structures are the result of horizontal shortening as well as dextral shearing. The latter is represented by the fl exing of fold-axes and clockwise rotation.

Diese Arbeit beschäftigt sich mit dem strukturellen Bau und der tektonischen Entwicklung der Lechtal-Decke im nordwestlichen Rätikon am Westende der Nördlichen Kalkalpen (NKA). Die Daten und Interpretationen beziehen sich zum Einen auf den gesamten Bereich der NKA im Rätikon westlich des Brandnertals und zum Anderen auf ein detailliert kartiertes Teilgebiet zwischen dem südlichen Brandnertal und dem südlichen Gamperdonatal. In- und außerhalb dieses Kartiergebiets konnten in Aufschlüssen der Arosazone, die das lokale Unterlager der Nördlichen Kalkalpen darstellt, kinematische Daten von Scherbändern erhoben werden. Auf der Basis der eigenen Arbeiten und publizierten Geologischen Karten der Region (Allemann 1985, Heissl 1965) wurde ein NW–SE-Profil durch das westliche Rätikon konstruiert und bilanziert. Die Anlage des Profils erfolgte senkrecht zum Überwiegenden Streichen der Großstrukturen die einen ausgeprägten Schuppen- und Faltenbau zeigen..., conference

Turbulence models are reviewed and discussed with respect to their applicability in oscillating flow modeling. The Larn-Brernhorst form of the low-Reynolds number k-/spl epsilon/ turbulence model is chosen for oscillating flow modeling. Computations of oscillating flow in a finite pipe are compared with experimental data. While deficiencies of the turbulence model are identified, the overall agreement is shown to be very satisfactory. The instantaneous friction coefficients for fully developed flow are documented. The use of an effective Valensi number is proposed.