bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermal shock behavior of hydrothermally conditioned e-glass fiber/epoxy composites
Authors: Chakraverty A. P. , Mohanty U. K. , Biswal B. B.
Published: August 2012

The glass fiber-reinforced polymer composites suffer from significant moisture absorption properties, moisture due to both the ambience and direct immersion in ordinary water during the course of their practical applications. The quantity of moisture absorbed and its effect on the composite component in any engineering application is also severely influenced by the temperature fluctuations. Hence the present work aims at evaluating the glass fiber/epoxy composite under hydrothermal exposure coupled with up and down-thermal shocks for various lengths of time. Inter-laminar shear strength (ILSS) values of shocked and non-shocked composite specimens were determined using INSTRON-1195 testing system. Low-temperature differential scanning calorimetry was used to monitor the glass transition temperature (Tg). A longer hydrothermal exposure showed an increase in the ILSS value after an initial low value. The ILSS seemed to vary with up and down-thermal shock differently for hydrothermally treated sample. Despite little variation in Tg value, the depression in the same was observed under up-thermal shock compared to down-thermal shock conditions. The fractographs of shocked and non-shocked specimen, as obtained from scanning electron microscope, divulged the chief mode of failure viz. fiber fragmentation and delamination.
Delivering London 2012: Transport operations delivery
Authors: Emmerson David
Published: August 2012

The scope of transport operations during the London 2012 Olympic and Paralympic Games was the most demanding that London's transport network has ever had to meet. Transport services in London carried 800 000 additional journeys on the busiest day at the Park. All while meeting the informal objective that ‘sport – not transport' dominated the headlines. The UK Olympic Delivery Authority (ODA) approach focused on minimum intervention overlaid with a bespoke holistic programme of service and infrastructure enhancements which allowed the numerous transport operators involved to adapt to play their part in delivery of transport for the games, without disrupting their established processes and ongoing responsibilities. The scale of the challenge and the necessity to ensure an integrated approach makes this work both significant and noteworthy. This paper explores the process and sets out the key lessons learned.
Matrix Metalloproteinases, Tissue Inhibitors of Matrix Metalloproteinases, and Inflammation in Cyclosporine A–Induced Gingival Enlargement: A Pilot In Vitro Study Using a Three‐Dimensional Model of the Human Oral Mucosa
Authors: Johanson Matthew , Zhao Xiang R. , Huynh‐Ba Guy , Villar Cristina C.
Published: August 2012

Background: It has been suggested that cyclosporine A (CsA) induces gingival enlargement by promoting an increase in the gingival extracellular matrix (ECM). Nonetheless, the variable occurrence of CsA‐induced gingival enlargement in patients receiving this medication indicates a multifactorial pathogenesis. Clinical observations suggest that local inflammation is associated with the development and severity of CsA‐induced gingival enlargement. Therefore, the purpose of this study is to investigate the effects of CsA and inflammation on the production of ECM homeostatic mediators.

Methods: The effects of CsA and inflammation (as assessed using interleukin [IL]‐1β) on the secretion of mediators involved in ECM homeostasis were determined using fibroblast monolayers and three‐dimensional (3D) models of the human oral mucosa. Fibroblast monolayers and 3D cultures were treated with CsA alone or in combination with IL‐1β for up to 72 hours, and the secretion of matrix metalloproteinases (MMPs) 1, 2, 3, 8, 9, 10, and 13 and tissue inhibitors of MMPs (TIMPs) 1, 2, and 4 into the culture medium was assessed using enzyme‐linked immunoassay–based antibody arrays.

Results: Fibroblast monolayers responded to CsA with no changes in the secretion of ECM mediators. Conversely, 3D cultures responded to CsA treatment with a reduction in MMP‐10 secretion. IL‐1β alone triggered higher secretory levels of MMPs in both fibroblast monolayers (MMP‐3 and MMP‐10) and 3D cultures (MMP‐9 and MMP‐10). Importantly, fibroblast monolayers and 3D cultures treated with a combination of IL‐1β and CsA showed a decrease in the MMP‐1/TIMP‐1 ratio.

Conclusions: These data support the hypothesis that inflammation may alter the pathogenesis of CsA‐induced gingival enlargement by promoting a synergistic decrease in the MMP‐1/TIMP‐1 ratio.
New Trends in Thromboxane and Prostacyclin Modulators
Authors: Dogne Jean -Michel , Leval Xavier de , Delarge Jacques , David Jean -Louis , Masereel Bernard initial
Published: August 2012

Thromboxane A 2 (TXA 2 ) and prostacyclin (PGI 2 ) are two labile products formed from arachidonic acid by the way of cyclooxygenase. An overproduction of thromboxane A 2 has been detected in a series of diseases whereby this prostanoid is assumed to contribute to the underlying pathomechanisms by its potent stimulation of platelet aggregation and smooth muscle contraction. This increased TXA 2 biosynthesis is frequently accompanied by a stimulation of prostacyclin formation which is one of the most potent inhibitors of platelet aggregation and smooth muscle contraction. Therefore, TXA 2 prostaglandin endoperoxide H 2 receptor antagonists, thromboxane synthase inhibitors and drugs which combine both activities have been developed with the aim to suppress the formation and/or the action of thromboxane A 2 . Since prostacyclin has been demonstrated to counterbalance the pathological effects of TXA 2 , several PGI 2 agonists have also been developed. This review will highlight the evolution and some of the latest findings in the field of prostacyclin and thromboxane A 2 modulators mainly those which are under clinical evaluation or marketed.
Series solutions for the flow in the vicinity of the equator of an MHD boundary-layer over a porous rotating sphere with heat transfer
Authors: Rashidi Mohammad , Mehr Navid
Published: August 2012

In this paper, an analytical method (DTM-Pad?) is employed to solve the flow
and heat transfer near the equator of an MHD boundary-layer over a porous
rotating sphere. This method is used to give solutions of nonlinear ordinary
differential equations with boundary conditions at infinity. The velocity
components in all directions (meridional, rotational and radial) and
temperature fields are derived. The obtained results are verified with the
results of numerical solution. A very good agreement can be observed between
them. The effect of involved parameters such as magnetic strength parameter,
rotation number, suction/blowing parameter and Prandtl number on the
all-different types of velocity components, temperature field and surface
shear stresses in meridional and rotational directions, infinite radial
velocity and rate of heat transfer is checked and discussed.
Woodrow Wilson on Education
Authors: Berlin Isaiah , Hardy Henry
Published: August 2012

In this 1960 article Isaiah Berlin compares Woodrow Wilson's emphasis on the need to educate university students for life in the real world with the difference between Oxford ‘realism’ and Cambridge ‘idealism’ in the nineteenth century. Oxford favoured a Wilsonian preference for general education over (but not to the exclusion of) pure scholarship, and Cambridge the cultivation of private life and personal relationships. Both universities were opposed to the excessive specialisation that Wilson deprecated.
Developing Participatory Approaches for Use in an Action Research Project with Teachers Who Support Children with Visual Impairment in Kenya and Uganda: Reflections on the Relational Praxis between Participants and Research Institutions
Authors: Lynch Paul , McLinden Mike , Douglas Graeme , McCall Steve , Muturi Mary , Bayo Asher , Mwaura Martha , Muga John
Published: August 2012

Participatory research is a broad term covering a range of approaches that are characterised by a focus on ‘action-oriented’ research involving researchers and participants working in collaboration to bring about positive change. These approaches emphasise engagement with co-researchers and the development and implementation of context-appropriate strategies that seek to empower and transform at a number of levels. This article explores the dynamics of a multi-agency and multinational research programme that investigated the working practices of specialist teachers of children with visual impairment in Uganda and Kenya. The research utilised a range of participatory methods, including workshops and a dedicated practice journal, to provide opportunities for participants to record information about their practice and share their experiences with colleagues. The article analyses the effectiveness of the approach, with a particular focus on the ‘relational praxis' between the project partners. This analysis highlights the complex nature of the collaborative relationships when research is transnational and operates across cultural, social and environmental contexts. Considerations are offered for research design in this area.
Comparative Study of University and Polytechnic Graduates in Finland: Implications of Higher Education on Earnings
Authors: Xia Belle Selene , Liitiäinen Elia , Rekola Mika
Published: August 2012

This study explores the implications of higher education on earnings in Finland. The challenges as well as opportunities of obtaining a university degree as compared to graduating from polytechnics are evaluated using the REFLEX (The Flexible Professional in the Knowledge Society) data. As a Nordic country, Finland is known for its educated population and the public emphasis on continuous learning but, nevertheless, there has been comparatively little research published internationally. The authors address the criticisms and drawbacks of higher education by analysing the performance of Finnish graduates in the labour market using the analysis of covariances. While debates concerning additional financing for higher education persist, it is acknowledged to be one of the solutions to the aging population and related economic problems in Finland. Based on the results from various Finnish educational institutions, the authors analyse the degree of match between investment in human capital and market demand.
The Moderating Effects of the Incentive System and Performance Measure on Managers' and Their Superiors' Expectations about the Manager's Effort
Authors: Cianci Anna M. , Kaplan Steven E. , Samuels Janet A.
Published: August 2012

The current study experimentally examines effort expectations (i.e., planned hours) for a manager made by participants in the role of the manager or the manager's superior. The experiment also manipulates the type of incentive system (i.e., bonus based on either strategic or all measures) and the type of performance measure (i.e., strategic or general). We predict and find that the participants in the manager role engage in self-enhancement (e.g., Pfeffer and Fong 2005; Sedikides and Gregg 2008). Specifically, the total hours that managers planned to work were more than the total hours their superiors expected the manager to work. We also find that both the type of incentive system and the type of performance measure moderate managers' tendency to engage in self-enhancement. Compared to a strategic incentive system, managers' self-enhancement was diminished under a comprehensive incentive system. Further, participants in the manager role engage in self-enhancement for planned strategic hours but not for planned general hours.

Data Availability: Available upon request.
The Apoptosis Inhibitor ARC Alleviates the ER Stress Response to Promote β-Cell Survival
Authors: McKimpson Wendy M. , Weinberger Jeremy , Czerski Lech , Zheng Min , Crow Michael T. , Pessin Jeffrey E. , Chua Streamson C. , Kitsis Richard N.
Published: August 2012

Type 2 diabetes involves insulin resistance and β-cell failure leading to inadequate insulin secretion. An important component of β-cell failure is cell loss by apoptosis. Apoptosis repressor with caspase recruitment domain (ARC) is an inhibitor of apoptosis that is expressed in cardiac and skeletal myocytes and neurons. ARC possesses the unusual property of antagonizing both the extrinsic (death receptor) and intrinsic (mitochondria/endoplasmic reticulum [ER]) cell death pathways. Here we report that ARC protein is abundant in cells of the endocrine pancreas, including >99.5% of mouse and 73% of human β-cells. Using genetic gain- and loss-of-function approaches, our data demonstrate that ARC inhibits β-cell apoptosis elicited by multiple inducers of cell death, including ER stressors tunicamycin, thapsigargin, and physiological concentrations of palmitate. Unexpectedly, ARC diminishes the ER stress response, acting distal to protein kinase RNA-like ER kinase (PERK) and inositol-requiring protein 1α, to suppress C/EBP homologous protein (CHOP) induction. Depletion of ARC in isolated islets augments palmitate-induced apoptosis, which is dramatically rescued by deletion of CHOP. These data demonstrate that ARC is a previously unrecognized inhibitor of apoptosis in β-cells and that its protective effects are mediated through suppression of the ER stress response pathway.
Activation of Enteroendocrine Membrane Progesterone Receptors Promotes Incretin Secretion and Improves Glucose Tolerance in Mice
Authors: Flock Grace B. , Cao Xiemin , Maziarz Marlena , Drucker Daniel J.
Published: August 2012

Glucagon-like peptide-1 (GLP-1) secretion is classically regulated by ingested nutrients. To identify novel molecular targets controlling incretin secretion, we analyzed enteroendocrine cell pathways important for hormone biosynthesis and secretion. We demonstrate that progesterone increases GLP-1 secretion and extracellular signal–related kinase 1/2 (ERK1/2) phosphorylation in enteroendocrine GLUTag cells via mechanisms sensitive to the mitogen-activated protein kinase inhibitor U0126. The stimulatory effects of progesterone (P4) or the synthetic progestin R5020 on ERK1/2 phosphorylation were independent of the classical progesterone receptor antagonist RU486. Furthermore, a cell-impermeable BSA–progesterone conjugate rapidly increased ERK1/2 phosphorylation and GLP-1 secretion. Knockdown of the membrane progesterone receptors Paqr5 or Paqr7 in GLUTag cells eliminated the stimulatory effect of R5020 and progesterone on GLP-1 secretion. Enteral progesterone administration increased plasma levels of GLP-1, glucose-dependent insulinotropic polypeptide (GIP), and insulin, and improved oral glucose tolerance in an RU486-insensitve manner in mice: however, systemic progesterone exposure did not improve glucose homeostasis. Unexpectedly, the glucoregulatory actions of enteral progesterone did not require classical incretin receptor signaling and were preserved in Glp1r−/− and Glp1r−/−:Gipr−/− mice. Intestine-restricted activation of membrane progesterone receptors may represent a novel approach for stimulation of incretin hormone secretion and control of glucose homeostasis.
Metabolic Syndrome Model Definitions Predicting Type 2 Diabetes and Cardiovascular Disease
Authors: Povel Cécile M. , Beulens Joline W. , van der Schouw Yvonne T. , Dollé Martijn E.T. , Spijkerman Annemieke M.W. , Verschuren W.M. Monique , Feskens Edith J.M. , Boer Jolanda M.A.
Published: August 2012

OBJECTIVE

Metabolic syndrome (MetS) is a cluster of abdominal obesity, hyperglycemia, hypertension, and dyslipidemia, which increases the risk for type 2 diabetes and cardiovascular diseases (CVDs). Some argue that MetS is not a single disorder because the traditional MetS features do not represent one entity, and they would like to exclude features from MetS. Others would like to add additional features in order to increase predictive ability of MetS. The aim of this study was to identify a MetS model that optimally predicts type 2 diabetes and CVD while still representing a single entity.

RESEARCH DESIGN AND METHODS

In a random sample (n = 1,928) of the EPIC-NL cohort and a subset of the EPIC-NL MORGEN study (n = 1,333), we tested the model fit of several one-factor MetS models using confirmatory factor analysis. We compared predictive ability for type 2 diabetes and CVD of these models within the EPIC-NL case-cohort study of 545 incident type 2 diabetic subjects, 1,312 incident CVD case subjects, and the random sample, using survival analyses and reclassification.

RESULTS

The standard model, representing the current MetS definition (EPIC-NL comparative fit index [CFI] = 0.95; MORGEN CFI = 0.98); the standard model excluding blood pressure (EPIC-NL CFI = 0.95; MORGEN CFI = 1.00); and the standard model extended with hsCRP (EPIC-NL CFI = 0.95) had an acceptable model fit. The model extended with hsCRP predicted type 2 diabetes (integral discrimination index [IDI]: 0.34) and CVD (IDI: 0.07) slightly better than did the standard model.

CONCLUSIONS

It seems valid to represent the traditional MetS features by a single entity. Extension of this entity with hsCRP slightly improves predictive ability for type 2 diabetes and CVD.
Novel Risk Factors and the Prediction of Type 2 Diabetes in the Atherosclerosis Risk in Communities (ARIC) Study
Authors: Raynor L.A. , Pankow James S. , Duncan Bruce B. , Schmidt Maria I. , Hoogeveen Ron C. , Pereira Mark A. , Young J. Hunter , Ballantyne Christie M.
Published: August 2012

OBJECTIVE

The objective of this study was to determine potential added value of novel risk factors in predicting the development of type 2 diabetes beyond that provided by standard clinical risk factors.

RESEARCH DESIGN AND METHODS

The Atherosclerosis Risk in Communities (ARIC) Study is a population-based prospective cohort study in four U.S. communities. Novel risk factors were either measured in the full cohort or in a case-control sample nested within the cohort. We started with a basic prediction model, previously validated in ARIC, and evaluated 35 novel risk factors by adding them independently to the basic model. The area under the curve (AUC), net reclassification index (NRI), and integrated discrimination index (IDI) were calculated to determine if each of the novel risk factors improved risk prediction.

RESULTS

There were 1,457 incident cases of diabetes with a mean of >7.6 years of follow-up among 12,277 participants at risk. None of the novel risk factors significantly improved the AUC. Forced expiratory volume in 1 s was the only novel risk factor that resulted in a significant NRI (0.54%; 95% CI: 0.33–0.86%). Adiponectin, leptin, γ-glutamyl transferase, ferritin, intercellular adhesion molecule 1, complement C3, white blood cell count, albumin, activated partial thromboplastin time, factor VIII, magnesium, hip circumference, heart rate, and a genetic risk score each significantly improved the IDI, but net changes were small.

CONCLUSIONS

Evaluation of a large panel of novel risk factors for type 2 diabetes indicated only small improvements in risk prediction, which are unlikely to meaningfully alter clinical risk reclassification or discrimination strategies.
Laser Applications in Biomedicine. Part I: Biophysics, Cell Biology, and Biostimulation
Authors: Berns Michael W. , Nelson J. Stuart
Published: August 2012

The successful applications of lasers to biomedicine rely upon an adequate understanding of the principles of light interaction with tissue. These principles are based upon the fundamentals of photophysics and involve a variety of mechanisms of energy conversion: heat, photochemistry, non-thermal bond breaking, fluorescence, and mechanical shock waves. All of these mechanisms are discussed in the context of biomedical and basic cellular studies. In addition, the mechanism and use of low power (milliwatt) lasers are examined with respect to non-thermal biostimulation phenomena. Many of these applications, such as cell growth stimulation, immunologic response, and wound healing, may be based upon photochemical conversion of absorbed energy.
Laser Application in Otolaryngology — Head and Neck Surgery
Authors: Barat Michael , Ossoff Robert H.
Published: August 2012

Since the discovery of the laser in 1959, a wide variety of lasers have been developed with numerous clinical applications in medicine and surgery. Lasers have had a great impact on the surgical approach to both benign and malignant diseases in Otolaryngology-Head and Neck Surgery, and have enabled the otolaryngologist to manage diseases in the aerodigestive system primarily through an endoscopic approach. We will summarize the physical properties of the currently used lasers in otolaryngology, as well as their clinical applications.
CO2 Laser Engraving System for Relief Plate to Print Corrugated Cardboard
Authors: Wakabayashi K. , Sugishima N.
Published: August 2012

A very compact and economical CO2 laser engraving system to make relief plates for the purpose of printing corrugated cardboard has been developed. This system consists of a highly stable 500W CO2 laser and a high speed, easy handling image processing sub-system. In this paper several new developments are described. This image processing technique for CO2 laser raster scanning and engraving has been newly developed. Every binary image is converted to the relief plate more easier than other reported engraving systems.
Complete Particle Field Characterization with Optical Diagnostics
Authors: Bachalo W. D.
Published: August 2012

A discussion of the practical aspects of particle sizing using light scatter detection is presented. The primary focus is on single particle counter methods for performing in situ size and velocity measurements. One objective of the presentation is to provide information on the applicability and limitations of these methods when measurements in practical environments are required. The problem of dealing with irregularly-shaped particles is considered. Light scattered by such particles is not easily analyzed except in the near-forward direction. Examples of the scattered intensity as compared to that of spheres are presented. A method for performing an optical decon-volution to resolve the trajectory problem when using Gaussian beams is described. The method uses confocal beams along with a simple algebraic solution to determine the particle path through the beam. The phase Doppler method for obtaining the size and velocity of spherical particles is discussed and several examples of data obtained with this method are presented. This method allows the complete characterization of the particle field by providing measurements of the size and velocity, number density, volume flux, and temporal statistics. The time-of-arrival information of the particles can be used to analyze such phenomena as the formation of particle clusters in turbulent flows.
Simultaneous Laser Velocimeter and Concentration Measurement
Authors: Walker David T. , Tiederman William G.
Published: August 2012

Inability to predict the high Schmidt number mixling of a concentrated polymer solution injected into a channel flow of water motivated the development of a method for measuring the product of the velocity fluctuation normal to the wall and the fluctuation in the polymer concentration. Time-resolved concentration measurements were obtained using a laser-induced fluorescence technique. The injected fluid was marked with a fluorescent dye and the spatial distribution of the intensity of fluorescent light emitted from an argon-ion laser beam directed normal to the channel wall was measured with a line-scan camera. Concentration of the injected fluid was inferred from the dye concentration. A dual scatter, helium-neon laser Doppler velocimeter traversed along the line of the concentration measurements was used to measure the velocity normal to the wall. Successful implementation of this technique required very rapid sampling of the output from the line-array camera as well as a large addressable random access memory. Instantaneous and time-average results have been obtained for the injection of both water and a 700 ppm aqueous solution of SEPARAN AP-273 into fully developed channel flows of water at a Reynolds number of 42,800.
Optical Engineering — A New Form of Industrial Energy
Authors: Steen W. M.
Published: August 2012

A brief review OF the development of civilization on this planet leads to a fairly strong correlation between our ability to apply new forms of energy and the growth of our quality of life. With the comparatively recent invention of the laser, optical energy has become available in a form and at intensities which can be applied. This article examines some of the differences between optical energy and other forms of industrial energy with a view to suggesting where future growth may occur and why our grand-children may bask in a higher quality of life due to our efforts to apply this new form of energy. Some of the principle differences noted are: the current laser power densitities are amongst the highest available to industry today; that optical energy is amongst the easiest forms of energy to direct and shape; that this power can be delivered with very little signal noise, allowing a unique window into automation and “intelligent” processing; that the laser beam contains the properties of coherence and monochromaticity as yet unexplored by material processing engineers and that possibly the rapidly growing optical applications of laser, such as metrology, may soon reflect into material processing; that the very pure frequency of the laser beam and/or multi photon events may allow chemical processing which is unexpected thermo-dynamically; and finally, that it is very likely that there is a wealth of applications so novel that we have not seen even the possibilities yet — which was certainly the story with steam, electricity and oil.
Optical Methods in Flow Visualization
Authors: Yang Wen-Jei , Chen Yi
Published: August 2012

Optical techniques for flow visualization are presented, including light-sheet flow visualization, shadowgraphy, schlieren method, interferometry, holography, speckle photography, laser-induced fluorescence and thermography. The principles of these methods are briefly described and the examples of their applications to flow visualization are given.
The Energy Transfer Efficiency in Laser Welding Process
Authors: Kim T. H. , Albright Charles E. , Chiang Schichan
Published: August 2012

The process efficiency of laser beam welding was measured as a function of travel speed. Temperature measurements were carried out during the bead-on-plate laser welding of mild steel with a focused 2KW CO2 laser beam at various welding travel speeds. The laser welding process efficiency (power delivered to work/power in the beam) was calculated from the ratio of the heat content of the welded the specimen to the available laser beam energy (power × time). In the deep penetration welding region at intermediate travel speeds, the laser beam welding process efficiency (equal to the beam absorptance) was about 65%; but it was only about 28% in the shallow penetration region at high travel speeds. In deep penetration welding, multiple reflections within the penetration cavity enhance absorptance. A calculation based on four reflections within the cavity can account for the observed process efficiency.
Binary Phase Gratings for Materials Processing
Authors: Patt Paul J.
Published: August 2012

The feasibility of using a diffractive optical element, a phase grating, as a beam handling device for use in industrial laser material processing is examined. The binary phase grating is an efficient beam splitting device and is useful in many materials processing operations (welding, cutting, soldering, drilling) where a high degree of parallelism could significantly improve process throughput. Overall efficiency of etched quartz binary gratings agrees well with published predictions (nominal 70–90%). Copies of the grating formed in PMMA (acrylic) survived preliminary life tests (more than 1000 9-J pulses from a commercial multimode Nd-Glass laser) with no measurable change in performance. Conventional Small Outline (SO) IC electronic packages were both laser soldered and welded to substrates with one laser pulse. Beam splitting uniformity of desired images is within 10% for the original quartz gratings and for some PMMA copies. Conventional doublet achromat and planoconvex lenses are adequate for maintaining 10% uniformity of intensity. Splitting uniformity is experimentally evaluated with energy and focused spot (burn) tests on kapton (polyimide) and thin and thick metal samples using a pulsed industrial Nd laser.
Infrared Optical Fibers for Surgical Applications
Authors: Waynant R. W. , Ediger M. N. , Fink M.
Published: August 2012

The basic characteristics of fibers that are appropriate for surgical use in the infrared are reviewed. New fiber materials, such as sapphire, fluorozirconate and chalcogenide glasses, and polycrystalline fibers are discussed as well as their applicability for surgical procedures.
On Optical Methods in Particle Flow
Authors: Shimizu I. , Yang Wen-Jei
Published: August 2012

Some recently developed optical methods for the measurement, control and shape recognition of particle flow are presented including motion control of micro-particles by optical pressure, identification of particle groups by matched spatial filters, bidirectional light scattering/image processing, bidirectional light scattering/real time measurement, dual beam type particle counter, and speckle photography.
Erbium:YAG (2.94 μm) Laser Effects on Dental Tissues
Authors: Hoke James A. , Burkes E. Jeff , Gomes Edward D. , Wolbarsht Myron L.
Published: August 2012

Past trials with soft and calcified tissues have demonstrated that long pulse train (2.5 μs) Er:YAG (2.94 μm) laser may be used to ablate tooth structure of human teeth. Determination of physical and thermal damage to surrounding tissue during removal of enamel and dentin is a primary objective of this study. Extracted human teeth with thermal probes imbedded in the pulp chambers were submitted to cavity preparation using an Erbium YAG laser with water mist. Wavelength selection as well as use of a water mist during the procedure resulted in efficient tissue removal without significant surrounding damage. Ground sections and SEM sections of teeth showed little or no melting or ash formation in adjacent dentin and enamel and no visible change in the pulp chamber. The surfaces produced by laser ablation were rough and irregular with craters and grooves. Average temperature change in the pulp chamber monitored during tooth preparation was 2.2 degrees Centigrade. These findings suggest that constantly available water aids vaporization and microexplosions, increasing the efficiency of tooth structure removal, and aids in cooling of the tooth structures. The long pulse EnYAG (2.94 μm) laser may be an effective method for tooth reduction applications when used with a water mist.
Laser Welding Copper and Copper Alloys
Authors: Hashimoto Kaoru , Sato Takehiko , Niwa Koichi
Published: August 2012

We have developed a laser hermetic sealing technique that combines nickel plating with laser welding for copper and copper alloy bellows for general purpose large-scale computers. Laser welding of copper has been difficult because of copper's high thermal conductivity and reflectivity. However, laser welding nickel-plated copper results in deep penetration. To avoid corrosion induced at the dissimilar metal contact between nickel and copper, the nickel-plated copper was heat-treated before welding to obtain a nickel-copper solid solution. Then, the optimum plating thickness and heat-treatment conditions were determined. A 10 μm-thick nickel plating, heat-treated for 1 h at 1000°C was found to be best suited to laser welding. These conditions make the laser weld of copper and copper alloy strong. Tests indicate that this technique is suitable for laser welding copper and copper alloys.
Treatment of the Transplantable FANFT Induced Bladder Tumors with the Purpurin SnET2 and Red Light Emitted by a Pulsed Frequency Doubled Nd:YAG Laser
Authors: Selman Steven H. , Fitkin David L. , Keck Rick W. , Morgan Alan R. , Doiron Daniel R.
Published: August 2012

Photodynamic therapy of transplantable N-[4-(5-nitro-2-furyl)-2-thiazolyl] formamide-induced tumors engrafted onto Fischer CDF (F-344)/CrlBR rats that had been sensitized with the photosensitizer tin (II) etiopurpurin dichloride was performed in combination with visible light (∼660 nm) emitted by either a continuous wave argon-dye laser or a pulsed, frequency-doubled Nd:Yag laser. Tumor control was assessed either by tumor dry-weight 12 days after treatment or by the palpatory absence of tumor at 60 days after treatment. Both laser sources were effective in creating the desired photodynamic effect. This study demonstrates the potential for the use of a solid-state pulsed laser for photodynamic therapy when used in combination with the tumor sensitizer tin (II) etiopurpurin dichloride.
Impact of International Laser Safety Standards on Manufacturers. Part II
Authors: Weiner Robert
Published: August 2012

Manufacturers have an increasing concern about the need to satisfy different laser safety regulations as they market their products throughout the world. While the national and regional laser safety regulations are similar, the differences which exist do impact the product. The requirements may vary in measurement criteria and limits for classification, engineering features, and manuals and labels, as well as for reporting, testing, and certification. This paper discusses the impact of the primary differing requirements on specific product types and describes the manner in which the laser safety standards are being implemented.
ANSI Z136.2 Update: Ocular Effects of Laser Infrared Radiation
Authors: Ham William T. , Mueller Harold A.
Published: August 2012

Laser radiation employed in fiber optic communications systems is a possible hazard to the eyes of personnel working with or maintaining such equipment. To investigate the potential hazard of infrared laser wavelengths centered around 1550 nm we exposed the corneas of 12 Dutch belted rabbits to a laser diode furnished by Bell Laboratories. Maximum power output through a 4-meter fiber optic cable was 5.6 mW. Anesthetized and fully dilated rabbits were exposed for time durations of 1, 10 and 100 s to power levels ranging from 4 to 5.6 mW. There was no evidence of damage from 1 and 10 s exposures even at maximum power level. For 100 s exposures, threshold minimal effects were observed at 4.2 mW; levels of damage increased with power increase up to 5.6 mW, where there was partial loss of the corneal epithelial cell layer. Power levels used in these exposures were well above those expected to be encountered in fiber optic communication systems using wavelengths centered around 1550 nm but are useful for predicting levels at which ocular damage can be expected.
Fusion Zone Structures in Laser Welded Al-SiC Composites
Authors: McCay Mary H. , McCay T. Dwayne , Dahotre Narendra B. , Sharp C. Michael
Published: August 2012

Metal matrix composites continue to be desirable structural materials but difficulties in joining limit their usefulness. This paper describes the results of a study on the laser welding of A356-AI/SiC particulate composites. Three separate processing regimes are identified based upon analytical model predictions and metallographic analysis of the solidification structures.
Laser Triangulation Range Sensors: A Study of Performance Limitations
Authors: Buzinski Michael , Levine Alan , Stevenson Warren H.
Published: August 2012

Optical triangulation is a very old method of determining absolute distance to an object. In recent years laser range sensors utilizing this principle have seen growing use, particularly in the auto industry. More accurate versions are being employed for dimensional inspection operations where the sensor is often mounted on a coordinate measuring machine. Such a system offers the potential for rapid non-contact dimensional metrology. However, there are several factors which must be taken into account if accurate and reliable results are to be achieved. This paper examines problems which can be encountered when using laser triangulation range sensors. Results of a study comparing such sensors with conventional touch probes are presented and suggestions for improved sensor designs are made. The problem of accurately locating edges and other steeply contoured surface features is given special attention.
Application of an Excimer Laser Machining Technique in the Construction of an Optical Fiber Bus
Authors: Coyle Richard J. , Serafino A. J. , Grimes Gary J. , Bortolini James R.
Published: August 2012

An excimer laser technique was developed to machine precision tap openings in a polymer-clad silica optical fiber for use in the construction of an optical backplane. In this technique, a telescope was used to image the laser beam onto the surface of the fiber at the desired tap location. The cladding then was removed using a prescribed number of pulses from the excimer laser. Single optical fiber taps were constructed using an ultraviolet-curable acralate to attach a tap fiber to a laser-machined opening in a central fiber. Tap measurements were made on single taps constructed from 650 × 350 micron elliptical openings and 250 micron diameter circular openings. Tap measurements also were made on a triple tap assembly which was fabricated using elliptical tap openings. The elliptical openings, with the major axis oriented along the longitudinal axis of the fiber, were determined to be more suitable for tap construction. The results of this study indicate that excimer laser machining is a promising technique for construction of a linear tapped bus for optical backplanes.
Fracture Characteristics of an Aluminum Oxide Ceramic during Continuous Wave Carbon Dioxide Laser Cutting
Authors: Smith R. N. , Surprenant R. P. , Kaminski D. A.
Published: August 2012

A series of experiments was conducted to determine the influence of workpiece thickness, cutting speed, and beam power on the onset of fracture in aluminum oxide (Al2O3) during continuous wave CO2 laser cutting. Samples of Coors AD-96 substrate of thickness 0.040, 0.050, and 0.080 in. thick, respectively, were cut at combinations of feedrates and power levels to determine the conditions at which fracture of this ceramic occurs with respect to these two parameters. Plots of the lowest value of feedrate producing a fracture-free cut at a given power were constructed for each material thickness. To explain the results qualitatively, a simplified thermal analysis of the problem was conducted. The two-dimensional temperature field resulting from a moving line source was calculated analytically to determine the maximum temperature gradient expected in the workpiece as a function of power and feedrate. A similar numerical computation was carried out for a moving distributed cylindrical source, to simulate a laser spot, accounting in addition for the variation of thermal conductivity of the workpiece with temperature. Both models successfully predicted the trends observed in the experimental study where increasing feed-rates at a given power and workpiece thickness resulted in increasing temperature gradients while decreasing power at a given feedrate and workpiece thickness resulted in increasing temperature gradients.
Dynamic Laser Doppler Velocimetry on Solid Surfaces
Authors: Rajadhyaksha Milind M. , Stevenson Warren H.
Published: August 2012

This paper presents the results of a detailed analytical and experimental investigation into the accuracy of a differential laser Doppler velocimeter (LDV) for dynamic, solid surface velocity measurements made over very short averaging times on the order of one millisecond. Accuracy limitations are derived, along with operating conditions and signal processing considerations needed to optimize LDV performance. An experiment is described which demonstrates the use of an LDV to instantaneously and accurately measure rapid changes in velocity.
LASER CUTTING OF STEELS: A physical and chemical analysis of the particles ejected during cutting. Part II
Authors: Powell J. , Ivarson A. , Magnusson C.
Published: August 2012

This paper is a continuation of work published in an earlier edition of this journal[1]. Both papers deal with the results of a detailed analysis of the particles ejected from the cut zone during laser cutting of mild and stainless steels. Reference 1 presented the thermochemical data and discussion generated by the experimental investigation. This paper concentrates on the physical characteristics and metallography of the particles. Analysis techniques used included: Scanning Electron Microscopy, optical microscopy, metallography and particle sizing. The results from this extensive analysis have enabled the authors to postulate oxidation histories for the particles. In addition to this it has been possible to explain the variation in particle size for various material thicknesses.
Characterization of Laser Produced High Molybdenum Surface Alloys on Stainless Steel Substrates
Authors: Kumar Dilip , Sridhar K. , Biswas A. R. , Goswami G. L. , Deshmukh M. B.
Published: August 2012

High Mo surface alloys on stainless steels 304L and 316L were produced by laser surface alloying. For this, a layer of 60 μm thickness was overlaid on the substrates by plasma spraying of Mo powders. These were further treated by a Nd:YAG pulsed laser for alloying. Depths of alloying in the range of 440–1110 μm were achieved. Concentration in the range of 5.2–15.0 wt% Mo within the laser alloyed zone was, in general, uniform throughout. During alloying, in-situ heating at 700°C was required to prevent cracking in samples with 5.2–6.0 wt% Mo. Higher Mo content enhanced the cracking tendency and made it difficult to prevent cracking completely even at this temperature. Fully austenitic microstructure of the substrate metals transformed to austennitic-ferritic duplex for 5.2–9.0 wt% Mo and to fully ferritic for 15.0 wt% Mo. Primary solidification mode also changed to FA, FA + F and finally to F depending upon Mo content in the alloyed zone. Ferrite content in the alloyed zone was in the range of 31–79% depending upon amount of Mo.Microhardness was increased from 173 VHN for 316L to 198–790 VHN depending upon wt% Mo in the alloyed zone. Preliminary studies indicated that pitting potential in 3.5% NaCl aqueous solution improved substantially from 132 mV for 304L and 240 mV for 316L to 480 mV and 500 mV respectively for 5.5–6.0 wt% Mo in the alloyed zone.
LC-MS and FT-IR characterization of amber artifacts
Authors: Truică Georgiana , Teodor Eugenia , Litescu Simona , Radu Gabriel
Published: August 2012

This work focuses on using analytical methods, such as Fourier transform Infrared spectroscopy (FTIR) and high performance liquid chromatography (HPLC) with mass spectrometry (MS) detection to assess archaeological and geological amber. The main goal of this study is to apply the previously developed and optimized analytical methods in verifying criteria to ascribe and characterize the origin of materials found in archaeological sites. The proposed LC-MS method was successfully applied for the quantification of succinic acid content both in geological and archaeological samples of amber and offers excellent linearity between 0.1 and 5µg mL−1. The developed FTIR method provided some criteria which is able to differentiate between Baltic and Romanian amber (Romanite) that furthermore validates on archaeological amber artefacts.
Application of UV detection in HPLC in the total antioxidant potential assay
Authors: Wantusiak Paweł , Głód Bronisław
Published: August 2012

HPLC has been already used for the TAP estimation. Phenylalanine, salicylic, p-hydroxybenzoic (pHBA) or terephthalic (TPA) acids have been used as sensor compounds. Products of their reaction with the hydroxyl radicals, generated in the Fenton-like reaction, were analyzed using electrochemical or fluorescence detection. This paper describes the TAP assay based on the hydroxyl radicals reaction with pHBA, reversed-phase-HPLC separation and UV photometric detection. The elaborated assay has been used to evaluate TAP values of some apiculture products.
A new method of proof of Filippov’s theorem based on the viability theorem
Authors: Plaskacz Sławomir , Wiśniewska Magdalena
Published: August 2012

Filippov’s theorem implies that, given an absolutely continuous function y: [t
0; T] → ℝd and a set-valued map F(t, x) measurable in t and l(t)-Lipschitz in x, for any initial condition x
0, there exists a solution x(·) to the differential inclusion x′(t) ∈ F(t, x(t)) starting from x
0 at the time t
0 and satisfying the estimation $$\left| {x(t) - y(t)} \right| \leqslant r(t) = \left| {x_0 - y(t_0 )} \right|e^{\int_{t_0 }^t {l(s)ds} } + \int_{t_0 }^t \gamma (s)e^{\int_s^t {l(\tau )d\tau } } ds,$$ where the function γ(·) is the estimation of dist(y′(t), F(t, y(t))) ≤ γ(t). Setting P(t) = {x ∈ ℝn: |x −y(t)| ≤ r(t)}, we may formulate the conclusion in Filippov’s theorem as x(t) ∈ P(t). We calculate the contingent derivative DP(t, x)(1) and verify the tangential condition F(t, x) ∩ DP(t, x)(1) ≠ ø. It allows to obtain Filippov’s theorem from a viability result for tubes.
Georeferencing Historical Cartography: A Quality-Control Method
Authors: Favretto Andrea
Published: August 2012

The use of historical cartography within a GIS environment to realize long-term change-detection studies of a certain area has become an established and fairly generalized practice. As is well known, the prerequisite condition for such analyses is the thorough rectification of the historical map's digital format. This article offers a methodology for creating a form of “accuracy assessment” for georeferencing executed on a historical map, based on a comprehensible control procedure that can be completed within a reasonable time frame. The fundamental idea is to use a set number of points to measure the gap between their positions on a georeferenced historical map and the reality of the territory. The control procedure creates a series of parameters to be added as metadata on the georeferenced map, constituted by the mean error distance and consequent standard deviation and by the percentage of an area examined on a map, drawn from a control grid superimposed on it.
Psychiatric Disorders and Substance Use in Homeless Youth: A Preliminary Comparison of San Francisco and Chicago
Authors: Quimby Ernika G. , Edidin Jennifer P. , Ganim Zoe , Gustafson Erika , Hunter Scott J. , Karnik Niranjan S.
Published: August 2012

Youth homelessness is a growing problem in the United States. The experience of homelessness appears to have numerous adverse consequences, including psychiatric and substance use disorders. This study compared the frequencies of psychiatric disorders, including substance use, between homeless youth (18–24 years-old) in San Francisco (N = 31) and Chicago (N = 56). Subjects were administered the Mini International Neuropsychiatric Interview (M.I.N.I.) to assess DSM-IV-TR diagnoses and substance use disorders. Eighty-seven percent of the San Francisco youth, and 81% of the Chicago youth met criteria for at least one M.I.N.I. psychiatric diagnosis. Nearly two-thirds of the youth in both samples met criteria for a mood disorder. Approximately one-third met criteria for an anxiety disorder. Thirty-two percent of the San Francisco sample and 18% of the Chicago met criteria for Antisocial Personality Disorder. Approximately 84% of the San Francisco youth and 48% of the Chicago youth met criteria for a substance-related disorder, and more substances were used by San Francisco youth. In conclusion, the high rate of psychiatric disorders in homeless youth provides clear evidence that the mental health needs of this population are significant. Implications are discussed.