Sample records for subjects wearing scuba

  1. Scuba Club

    CERN Multimedia

    Club subaquatique


    Free Trial Dive Ever thought of exploring the surrealistic world of scuba diving? Well, now you can start by joining the CERN Scuba Diving Club. A big activity of the club is to provide training, within the French Federation system, for beginners right through to monitor level. The level 1 course starts this Autumn in the Varembé swimming pool in Geneva. Curious? Then why not come along for a free trial dive in Varembé swimming pool on the 12th or 19th of October 2011. Just bring your swim wear and we will provide the rest. Offer open to adults, minimum age limit 14 years. To sign up, send an email to

  2. Scuba Science. (United States)

    Glickstein, Neil


    Introduces an integrated unit on scuba science. Studies oxygen in kinetic theory, Boyle's law, Charles's law, Dalton's law, human circulatory and respiratory systems, and diving dangers such as decompression sickness. (YDS)

  3. Subjective assessment of contact lens wear by army aircrew. (United States)

    Lattimore, M R; Cornum, R L


    Because 23% of Army aviators are ametropic, contact lenses have drawn increased attention as a spectacle substitute to solve system compatibility problems. From November 1988 until October 1991, a series of contact lens research protocols were conducted to develop a comprehensive database on contact lens wear in varied environments. Questionnaires were used to assess suitability and acceptability of routine contact lens wear. Responses from 202 subjects were obtained from September 1989 through September 1991. The questions explored operational and safety of flight issues of contact lens wear. Subjects overwhelmingly approved of contact lens use in all settings: 95% expressed greater combat readiness and effectiveness with contact lenses, 98% felt contact lens use (and maintenance) in the cockpit had no adverse impact on safety of flight, and 98% endorsed the routine use of contact lenses. These data highlight Army aircrew acceptance of contact lens use.

  4. Scuba club

    CERN Multimedia

    Scuba club


    The CERN Scuba club will be offering a free trail scuba dive sessions for anyone interested in trying this passionate activity. You don't have to be a daredevil or a great swimmer. Anyone curious to try can have a go. So don't miss the golden opportunity to discover a whole new fascinating world, taking your first breaths underwater! Two separate sessions will be help on Wednesday 7th October and Wednesday 14th October, both starting at 19:00 at the Varembe Swimming pool, 46 Avenue Giuseppe-Motta, 1202 Geneva. To sign up send an email to: (please indicate which date you wish to attend. You may only attend one). This event is open to adults and young people 14+. Minors must be accompanied by a parent. More information will soon be made available at the club website

  5. Scuba club

    CERN Multimedia

    Scuba club


    The CERN Scuba club will be offering a free trail scuba dive sessions for anyone interested in trying this passionate activity. You don't have to be a daredevil or a great swimmer. Anyone curious to try can have a go. So don't miss the golden opportunity to discover a whole new fascinating world, taking your first breaths underwater! Two separate sessions will be help on Wednesday 24th September and Wednesday 1st October, both starting at 19:00 at the Varembe Swimming pool, 46 Avenue Giuseppe-Motta, 1202 Geneva. To sign up send an email to: (please indicate which date you wish to attend. You may only attend one). This event is open to adults and young people 14+. Minors must be accompanied by a parent. More information will soon be made available at the club website

  6. Scuba Club

    CERN Document Server

    Club subaquatique


    Ever thought of exploring the surrealistic world of scuba diving? Well, now you can start by joining the CERN Scuba Diving Club. Since 1963, the CSC has been organising diving trips, lessons and much more to thousands of divers. The main activity of the club is providing training, within the French Federation system, for beginners right through to monitor level. The level 1 course starts this autumn in the Varembé swimming pool in Geneva. Twice a year, the CSC organizes an outing to the Mediterranean. Open to all, the first is usually held in May to finalise the level 1 training while the second, more of a family event, is in the autumn. An excellent atmosphere is guaranteed! Other activities include an underwater photography and video section as well as an underwater biology section. The two are complementary and are animated by qualified and experienced teachers. Curious? Then why not come along for a free trial dive in Varembé swimming pool on the 12th and 19th of October 2011....

  7. Alveolar Hemorrhage After Scuba Diving: A Case Report

    Directory of Open Access Journals (Sweden)

    Ming-Ju Tsai


    Full Text Available Self-contained underwater breathing apparatus (scuba diving is increasingly popular in Taiwan. There are few references in the literature regarding pulmonary hemorrhage as the sole manifestation of pulmonary barotrauma in scuba divers, and no study from Taiwan was found in the literature. We present the case of a 25-year-old man who suffered alveolar hemorrhage related to pulmonary barotrauma as a complication of scuba diving. To our knowledge, this is the first case report describing a Taiwanese subject suffering from non-fatal pulmonary hemorrhage after scuba diving.

  8. Scuba Diving Safety (United States)

    ... and Scuba Schools International (SSI). Basic courses involve classroom instruction, as well as training in pools and ... Read Article >>Knee Bracing: What Works? Visit our interactive symptom checker Visit our interactive symptom checker Get ...

  9. CERN Scuba Diving Club

    CERN Multimedia

    Club Subaquatique du CERN


    Interested in scuba diving? Fancy a fun trial dive? Like every year, the CERN Scuba Diving Club is organizing two free trial dive sessions. Where? Varembé Swimming Pool, Avenue Giuseppe Motta 46, 1202 Genève When? 25th October and 1st November at 19:15 (one session per participant) Price? Trial dives are FREE! Swimming pool entrance 5,40 CHF. What to bring? Swimwear, towel, shower necessities and a padlock – diving equipment will be provided by the CSC. For more information and to subscribe, follow the link below: Looking forward to meeting you!

  10. Wear rates of highly cross-linked polyethylene humeral liners subjected to alternating cycles of glenohumeral flexion and abduction. (United States)

    Peers, Sebastian; Moravek, James E; Budge, Matthew D; Newton, Michael D; Kurdziel, Michael D; Baker, Kevin C; Wiater, J Michael


    Although short-term outcomes of reverse total shoulder arthroplasty have been promising, long-term success may be limited due to device-specific complications, including scapular notching. Scapular notching has been explained primarily as mechanical erosion; however, the generation of wear debris may lead to further biologic changes contributing to the severity of scapular notching. A 12-station hip simulator was converted to a reverse total shoulder arthroplasty wear simulator subjecting conventional and highly cross-linked ultra-high-molecular-weight polyethylene humeral liners to 5 million cycles of alternating abduction-adduction and flexion-extension loading profiles. Highly cross-linked polyethylene liners (36.5 ± 10.0 mm(3)/million cycle) exhibited significantly lower volumetric wear rates compared with conventional polyethylene liners (83.6 ± 20.6 mm(3)/million cycle; P linked polyethylene (P linked wear particles had an equivalent circle diameter significantly smaller than wear particles from conventional polyethylene (P linked polyethylene liners significantly reduced polyethylene wear and subsequent particle generation. More favorable wear properties with the use of highly cross-linked polyethylene may lead to increased device longevity and fewer complications but must be weighed against the effect of reduced mechanical properties. Copyright © 2015 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

  11. Effects of long-term soft contact lens wear on the corneal thickness and corneal epithelial thickness of myopic subjects. (United States)

    Lei, Yulin; Zheng, Xiuyun; Hou, Jie; Xu, Baozeng; Mu, Guoying


    To perform safe and successful corneal refractive surgery on myopic patients, corneal thickness (CT) and corneal epithelial thickness (CET) must be accurately measured. Numerous individuals with myopia wear soft contact lenses (SCLs) for the correction of visual acuity but may subsequently undergo corneal refractive surgery. The aim of the present study was therefore to investigate the effects of long-term SCL wear on the CT and the CET of myopic subjects in order to guarantee the safety and accuracy of subsequent corneal refractive surgeries. Fifty-six subjects prepared to receive refractive surgery at Jinan Mingshui Eye Hospital (Zhangqiu, China) from April to July 2013 were included in the study. CT and CET were measured in subjects immediately following discontinued SCL wear (group I, 56 eyes), and subsequently following >two weeks of discontinued SCL wear (group II, 56 eyes). Ninety-four subjects with no history of corneal contact lens wear were enrolled as a control group. The CT and CET were measured at positions with a radius of 0.0‑1.0, 1.0-2.5 (divided into eight quadrants) and 2.5-3.0 mm (divided into eight quadrants) away from the corneal center using the RTVue-100 Fourier-domain anterior segment optical coherence tomography system. A significant decrease in the CT of the subjects in group II was observed, compared with that of group I and the control group (P<0.05). A significant decrease was observed in the CET of groups I and II compared with that of the control group (P<0.05). Following discontinuation of SCL wear, CET increased. However, the increased CET was unable to reach the normal range exhibited by the control group. Edema and thinning of the corneal stroma, as well as thinning of the corneal epithelium were observed in groups I and II. In conclusion, it was proposed that in clinical practice, for myopic patients following long-term SCL wear, CT and CET should be determined ≥ two weeks following discontinuation of SCL wear, once a stable

  12. Does wearing a functional knee brace affect hamstring reflex time in subjects with anterior cruciate ligament deficiency during muscle fatigue? (United States)

    Lam, Rita Y; Ng, Gabriel Y; Chien, Eric P


    To evaluate the effects of wearing a functional knee brace and muscle fatigue on hamstring reflex time in subjects with anterior cruciate ligament (ACL) deficiency. Repeated-measures clinical trial. Outpatient physical therapy department. Sixteen subjects with ACL deficiency. Subjects tested with and without a functional knee brace before and after an exercise protocol designed to fatigue the knee muscles. Latency of hamstring reflex muscle activity after sudden perturbation of the knee. Wearing a knee brace shortened the hamstring reflex latency regardless of fatigue (F(1,15)=20.62, Pknee brace facilitated hamstring muscle reflex, but muscle fatigue lengthened the hamstring reflex latency. Subjects with ACL deficiency should not rely on the knee brace to facilitate hamstring reflex for joint protection during prolonged sporting activities when muscles are fatigued. Copyright 2002 by the American Congress of Rehabilitation Medicine and the American Academy of physical Medicine and Rehabilitation

  13. Epinastine 0.05% ophthalmic solution in contact lens-wearing subjects with a history of allergic conjunctivitis. (United States)

    Nichols, Kelly K; Morris, Scot; Gaddie, Ian B; Evans, David


    To assess the comfort and efficacy of epinastine 0.05% ophthalmic solution in contact lens wearers with a history of allergic conjunctivitis and contact lens intolerance during allergy season. One hundred forty-six subjects were enrolled in a multicenter, open-label study. Enrolled subjects instilled rewetting drops twice a day for a one-week run-in period, then were randomized to epinastine 0.05% twice a day plus rewetting drops as required (n = 75) or rewetting drops alone as required (minimum use twice a day) (n = 71). Subjects recorded the length of time that contact lens wear was comfortable, the total time of wear, ocular itch, overall comfort, and use of rewetting drops during the run-in period, at baseline, and on days 2 to 7 of the treatment period. Subjects averaged 34 years of age; 79% were female. No significant differences were shown at baseline between subjects treated with epinastine 0.05% twice a day plus rewetting drops and control subjects treated with rewetting drops alone. Averaged over the treatment period, epinastine provided significant increases in comfortable wearing time (1.33 +/- 2.89 vs. 0.43 +/- 2.28 hr, P=0.012) and total wearing time (0.35 +/- 1.87 vs. -0.32 +/- 1.81 hr, P=0.008) compared with controls. Epinastine users reported less frequent additional rewetting drop use on average by 0.56 uses per day, which was significantly different than controls (reduction of 0.06 uses per day; P=0.012). Epinastine provided significantly greater improvements from baseline in ocular itch and overall eye comfort compared with rewetting drops alone (Pcontact lens wearers.

  14. Recreational scuba divers' knowledge regarding the audiological ...

    African Journals Online (AJOL)

    Background: The sport of scuba diving may be associated with possible injuries, especially those concerning the auditory system. Research available focuses on the implications of recreational scuba diving on the auditory system. However, there is a lack of information regarding the knowledge of recreational scuba divers ...

  15. 46 CFR 197.430 - SCUBA diving. (United States)


    ... 46 Shipping 7 2010-10-01 2010-10-01 false SCUBA diving. 197.430 Section 197.430 Shipping COAST... GENERAL PROVISIONS Commercial Diving Operations Specific Diving Mode Procedures § 197.430 SCUBA diving. The diving supervisor shall insure that— (a) SCUBA diving is not conducted— (1) Outside the no...

  16. 29 CFR 1910.424 - SCUBA diving. (United States)


    ... 29 Labor 5 2010-07-01 2010-07-01 false SCUBA diving. 1910.424 Section 1910.424 Labor Regulations... OCCUPATIONAL SAFETY AND HEALTH STANDARDS Commercial Diving Operations Specific Operations Procedures § 1910.424 SCUBA diving. (a) General. Employers engaged in SCUBA diving shall comply with the following...

  17. Forecast of reliability for mechanical components subjected to wearing; Pronostico de la fiabilidad de componentes mecanicos sometidos a desgaste

    Energy Technology Data Exchange (ETDEWEB)

    Angulo-Zevallos, J.; Castellote-Varona, C.; Alanbari, M.


    Generally, improving quality and price of products, obtaining a complete customer satisfaction and achieving excellence in all the processes are some of the challenges currently set up by every company. To do this, knowing frequently the reliability of some component is necessary. To achieve this goal, a research, that contributes with clear ideas and offers a methodology for the assessment of the parameters involved in the reliability calculation, becomes necessary. A parameter closely related to this concept is the probability of product failure depending on the operating time. It is known that mechanical components fail by: creep, fatigue, wear, corrosion, etc. This article proposes a methodology for finding the reliability of a component subject to wear, such as brake pads, grinding wheels, brake linings of clutch discs, etc. (Author)

  18. Tribological performance evaluation of coated steels with TiNbCN subjected to tribo-chemical wear in Ringers solution

    Energy Technology Data Exchange (ETDEWEB)

    Caballero G, J.; Aperador, W. [Universidad Militar Nueva Granada, Volta Research Group, 101-80 Bogota (Colombia); Caicedo, J. C., E-mail: [Universidad del Valle, Tribology Polymers, Powder Metallurgy and Processing of Solid Recycled Research Group, Cali (Colombia)


    With the aim of generating solutions against the deterioration of the joint prostheses, it was studied the tribo-corrosive behavior of titanium niobium carbonitride (TiNbCN) deposited on stainless steel AISI 316 LVM using the technique of magnetron sputtering physical vapor deposition. The tests were performed in a balanced saline solution (Ringers solution) which represents the characteristics of the body fluids, using an equipment where the micro-abrasive wear is generated by the contact of micro particles in the system; the micro-abrasion-corrosion mechanism is described by means of the incorporation of an electrochemical cell consisting of three electrodes. Both the substrate and the coating, were subjected to micro-abrasive wear simultaneously with the electrochemical tests of Tafel polarization curves and electrochemical impedance spectroscopy (EIS); subsequently of the tests, the specimens were analyzed by optical microscopy and scanning electron microscopy characterizing the surface morphology. It was observed that the coating presents an increase in its corrosion and wear resistance with the presence of a simulated biological fluid. The samples were characterized via X-ray diffraction. (Author)

  19. An upgraded SCUBA-2 for JCMT (United States)

    Bintley, Dan; Dempsey, Jessica T.; Friberg, Per; Holland, Wayne S.; MacIntosh, Michael J.


    SCUBA-2 is a state of the art wide field camera on the JCMT. SCUBA-2 has been fully operational since November 2011, producing a wide range of science results, including a unique series of survey programs. A new large survey programme commenced in 2015, which included for the first time, polarisation sensitive measurements using POL-2, the polarimeter ancillary instrument. We discuss proposals and the science case for upgrading SCUBA-2 with new detector arrays that will keep SCUBA-2 and the JCMT at the forefront of continuum submillimetre science.

  20. Objective and subjective assessing efficacy of a lubricating drop in eyes wearing silicone hydrogel contact lenses

    Directory of Open Access Journals (Sweden)

    Amir Asharlous


    Conclusion: Our results showed that although the lubricating drop did not improve the tear film stability and optical quality in the silicone hydrogel contact lens wearers, subjects experienced a subjective improvement.

  1. Physical activity after surgically obtained weight loss: study with a SenseWear armband in subjects undergoing biliopancreatic diversion. (United States)

    Gradaschi, Raffaella; Camerini, Giovanni; Carlini, Flavia; Sukkar, Samyr; Sopinaro, Nicola; Adami, Gian Franco


    This study aimed to understand the role of the extra load of body mass in limiting physical activity and in preventing an active lifestyle in severely obese patients. The study was carried out in a University Hospital setting, and investigates severely obese patients, having undergone biliopancreatic diversion (BPD) for obesity and control subjects with a body weight closely similar to that of the BPD subjects; energy intake was evaluated by alimentary interview and energy expenditure was assessed with the Body Media SenseWear® Pro armband (SWA). SWA metabolic efficiency (MET) was negatively associated with body mass index values (ρ = -0.464, p active persons (27% vs. 0 and 7%, respectively) and a lower number of sedentary persons (27% vs. 70 and 43%, respectively) was found (p physical activity and leading to a sedentary lifestyle.

  2. 29 CFR 1926.1084 - SCUBA diving. (United States)


    ... 29 Labor 8 2010-07-01 2010-07-01 false SCUBA diving. 1926.1084 Section 1926.1084 Labor Regulations...) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Diving Specific Operations Procedures § 1926.1084 SCUBA diving. Note: The requirements applicable to construction work under this section are identical to those...

  3. Teaching Persons with Disabilities to SCUBA Diving. (United States)

    Jankowski, Louis W.

    This booklet is designed to sensitize and inform the scuba diving instructor on appropriate attitudes and successful methods for teaching scuba diving to persons with physical disability. It addresses misconceptions about people with disabilities and the importance of effective two-way communication and mutual respect between instructors and…

  4. Introduction to Scuba Diving. Diver Education Series. (United States)

    Somers, Lee H.

    Scuba diving is often referred to as a "recreational sport." However, the term "sport" sometimes implies erroneous connotations and limits understanding. Scuba diving can be an avocation or a vocation. It is a pastime, a pursuit, or even a lifestyle, that can be as limited or extensive as one makes it. A persons level of commitment, degree of…

  5. Ear Disorders in Scuba Divers

    Directory of Open Access Journals (Sweden)

    MH Azizi


    Full Text Available History of underwater diving dates back to antiquity. Breath-hold technique in diving was known to the ancient nations. However, deep diving progressed only in the early decades of the 19th century as the result of advancements in efficient underwater technologies which subsequently led to invention of sophisticated sets of scuba diving in the 20th century. Currently, diving is performed for various purposes including commercial, recreational, military, underwater construction, oil industry, underwater archeology and scientific assessment of marine life. By increasing popularity of underwater diving, dive-related medical conditions gradually became more evident and created a new challenge for the health care professionals, so that eventually, a specialty the so-called “diving medicine” was established. Most of the diving-associated disorders appear in the head and neck. The most common of all occupational disorders associated with diving are otologic diseases. External otitis has been reported as the most common otolaryngologic problem in underwater divers. Exostosis of the external ear canal may be formed in divers as the result of prolonged diving in cold waters. Other disorders of the ear and paranasal sinuses in underwater divers are caused by barometric pressure change (i.e., barotraumas, and to a lesser extent by decompression sickness. Barotrauma of the middle ear is the most prevalent barotrauma in divers. The inner ear barotraumas, though important, is less common. The present paper is a brief overview of diving-related ear disorders particularly in scuba divers.

  6. Short-term corneal changes with gas-permeable contact lens wear in keratoconus subjects: a comparison of two fitting approaches. (United States)

    Romero-Jiménez, Miguel; Santodomingo-Rubido, Jacinto; Flores-Rodríguez, Patricia; González-Méijome, Jose-Manuel


    To evaluate changes in anterior corneal topography and higher-order aberrations (HOA) after 14-days of rigid gas-permeable (RGP) contact lens (CL) wear in keratoconus subjects comparing two different fitting approaches. Thirty-one keratoconus subjects (50 eyes) without previous history of CL wear were recruited for the study. Subjects were randomly fitted to either an apical-touch or three-point-touch fitting approach. The lens' back optic zone radius (BOZR) was 0.4mm and 0.1mm flatter than the first definite apical clearance lens, respectively. Differences between the baseline and post-CL wear for steepest, flattest and average corneal power (ACP) readings, central corneal astigmatism (CCA), maximum tangential curvature (KTag), anterior corneal surface asphericity, anterior corneal surface HOA and thinnest corneal thickness measured with Pentacam were compared. A statistically significant flattening was found over time on the flattest and steepest simulated keratometry and ACP in apical-touch group (all pcontact lens wear (all plens wear. Copyright © 2014 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

  7. Tribological studies of eutectic Aluminum-Silicon alloys used for automotive engine blocks subjected to sliding wear damage (United States)

    Xue, Guijun

    The microstructures and wear performances of linerless engine cylinder blocks made of two eutectic Al-Si alloys with different Si morphologies were characterized after the engine tests. Overall, both the Al-11 wt. % Si alloy and the Al-12.6 wt. % Si alloy provided similar wear performance. Block-on-ring wear tests were applied to the Al-11% Si alloy. The MW regime in air consisted of two sub-regimes: MW-1 and MW-2. The argon atmosphere produced a 10-fold reduction in wear rates and the formation of LMW regime at loads less than 10 N. The metallic tribolayers formed in the MW under argon atmosphere were uniform and stable, resulting lower wear rates than those in air. The mechanism of material removal under argon atmosphere was delimination. The SW occurring in argon was observed at a relatively low load, compared to an air atmosphere. Wear was also more sensitive to applied load in the argon atmosphere.

  8. Wear surface damage of a Stainless Steel EN 3358 aeronautical component subjected to sliding

    Directory of Open Access Journals (Sweden)

    Ferdinando Felli


    Full Text Available The present paper describes the failure analysis of an aircraft component subjected to several episodes of in service failure, resulted in loss of the aircraft safety. Modern aircrafts are provided with mechanical systems which have the task to open not pressurized hatches during landing. The components of such systems are subject to considerable mechanical stresses in harsh environment (presence of moisture and pollutants, significant and sudden temperature variations. The system is constituted by a sliding piston, a related nipple and by a locking system consisting of 4 steel spheres which are forced into a countersink machined on the piston when the hatches is open. The whole system is activated by a preloaded spring. The machined parts, nipple and piston, are made of EN3358 steel (X3CrNiMo13-8-2, a precipitation hardening stainless steel with very low content of carbon often used in the aerospace. The samples provided by the manufacturer present different types of damage all referable to phenomena relative to the sliding of the piston inside the nipple. The present paper describes the different damage observed and the microstructure of the material, then are reported the results obtained from the characterization of the material of the samples by means of optical and electronic microscopy, carried out to define the mechanisms involved in the system seizure. In order to define the primary cause of failure and to propose solutions to be adopted, also analyzing the criticality of using this PH stainless steel for this application, the results of different tests were compared with system design and working data.

  9. Wearing weighted backpack dilates subjective visual duration: The role of functional linkage between weight experience and visual timing

    Directory of Open Access Journals (Sweden)

    Lina eJia


    Full Text Available Bodily state plays a critical role in our perception. In the present study, we asked the question whether and how bodily experience of weights influences time perception. Participants judged durations of a picture (a backpack or a trolley bag presented on the screen, while wearing different weight backpacks or without backpack. The results showed that the subjective dura-tion of the backpack picture was dilated when participants wore a medium weighted backpack relative to an empty backpack or without backpack, regardless of identity (e.g., color of the visual backpack. However, the duration dilation was not manifested for the picture of trolley bag. These findings suggest that weight experience modulates visual duration estimation through the linkage between the wore backpack and to-be-estimated visual target. The con-gruent action affordance between the wore backpack and visual inputs plays a critical role in the functional linkage between inner experience and time perception. We interpreted our findings within the framework of embodied time perception.

  10. SCUBA-2 arrays to system interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Duncan, W. E-mail:; Audley, D.; Holland, W.; Atkinson, D.; Baillie, T.; Cliffe, M.; Ellis, M.; Gao, X.; Gostick, D.; Hodson, T.; Kelly, D.; MacIntosh, M.; McGregor, H.; Peacocke, T.; Smith, I.; Robson, I.; Walton, A.; Parkes, W.; Dunare, C.; Smith, S.; Terry, J.; Stevenson, T.; Gundlach, A.; Ruthven, A.; Ade, P.; Tucker, C.; Gannaway, F.; Walker, I.; Sudiwala, R.; Woodcraft, A.; Griffin, M.; Bintley, D.; Schulte, E.; Fich, M.; Kycia, J.; Halpern, M.; Molnar, J.; Burger, B.; Naylor, D.; Bastien, P.; Mitchell, G.; Irwin, K.; Hilton, G.; Ullom, J.; Reintsema, C.; Vale, L.; Ferreira, L.; Doriese, W


    Submillimeter common user bolometer array (SCUBA)-2 is a wide field sub-mm bolometer camera designed to replace the existing SCUBA instrument on the JCMT in Hawaii. It will be many hundreds of times faster in large area mapping than SCUBA and will also go deeper in a single frame. It will enable the many discoveries of SCUBA to be followed up with deep systematic surveys and help act as a pathfinder for the ALMA interferometer. The key technologies for making the arrays have been demonstrated and will be put together to fabricate the first prototype later this year (2003). The wide field nature of the SCUBA-2 bolometer camera, combined with the diffraction limit at sub-mm wavelengths, leads to physically large focal planes where the issues of stray light control, magnetic shielding, and electrical, thermal and mechanical connection must be carefully addressed in order to realise a successful instrument. We describe the solutions we have adopted for these problem areas.

  11. Finding Environmental Knowledge in SCUBA-Based Textual Materials (United States)

    Gündogdu, Cemal; Aygün, Yalin; Ilkim, Mehmet


    As marine environments within the adventure domain are future key-settings for recreational SCUBA diving experience, SCUBA-based textual materials should provide insight into environmental knowledge that is well connected to the novice divers' behaviour and attitude. This research is concerned with a major recreational SCUBA diver manual for…

  12. Chain of events analysis for a scuba diving fatality. (United States)

    Lippmann, John; Stevenson, Christopher; McD Taylor, David; Williams, Jo; Mohebbi, Mohammadreza


    A scuba diving fatality usually involves a series of related events culminating in death. Several studies have utilised a chain of events-type analysis (CEA) to isolate and better understand the accident sequence in order to facilitate the creation of relevant countermeasures. The aim of this research was to further develop and better define a process for performing a CEA to reduce potential subjectivity and increase consistency between analysts. To develop more comprehensive and better-defined criteria, existing criteria were modified and a template was created and tested using a CEA. Modifications comprised addition of a category for pre-disposing factors, expansion of criteria for the triggers and disabling agents present during the incident, and more specific inclusion criteria to better encompass a dataset of 56 fatalities. Four investigators (raters) used both the previous criteria and this template, in randomly assigned order, to examine a sample of 13 scuba diver deaths. Individual results were scored against the group consensus for the CEA. Raters' agreement consistency was compared using the Index of Concordance and intra-class correlation coefficients (ICC). The template is presented. The index of concordance between the raters increased from 62% (194⁄312) using the previous criteria to 82% (257⁄312) with use of this template indicating a substantially higher inter-rater agreement when allocating criteria. The agreement in scoring with and without template use was also quantified by ICC which were generally graded as low, illustrating a substantial change in consistency of scoring before and after template use. The template for a CEA for a scuba diving fatality improves consistency of interpretation between users and may improve comparability of diving fatality reports.

  13. Are recreational SCUBA divers with asthma at increased risk? (United States)

    Ustrup, Amalie S; Ulrik, Charlotte S


    Asthma has traditionally been regarded as a contraindication to self-contained underwater breathing apparatus (SCUBA) diving, although large numbers of patients with asthma dive. The aim of the review is to provide an update on current knowledge on potential disease-related hazards in SCUBA divers with asthma. Systematic literature review based on the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. Seven studies met the criteria for inclusion in the review (comprising a total of 560 subjects). Five studies reported an increased risk for developing diving-related injuries in divers with asthma, based on case reports (n = 1), case history combined with objective assessment (n = 1), and dives and/or simulated dives (n = 3). The remaining studies (n = 2) were based on self-reported diving habits in divers suffering from asthma, obtained from anonymous questionnaires in diving magazines, reported no diving-related injuries among respondents. Due to limited evidence it is difficult to draw valid conclusions, but there are indications that recreational divers with asthma may be at increased risk for diving-related injuries compared to non-asthmatic divers. However, it is of at most importance to obtain further evidence from large-scale, well-designed studies.

  14. Facial Baroparesis Caused by Scuba Diving (United States)

    Kamide, Daisuke; Matsunobu, Takeshi; Shiotani, Akihiro


    Middle ear barotrauma is one of the common complications of SCUBA diving representing acute otalgia, hearing loss, and bleeding. But occurrence of facial palsy is rare. Here we report a case of a 30-year-old navy diver suffered middle ear barotrauma with transient facial palsy after SCUBA diving. He felt difficulty in equalizing the pressure in middle ear with Valsalva maneuver during diving, and suffered right facial palsy and aural fullness after diving. Clinical examination showed remarkable bulging of the right tympanic membrane and right facial palsy without other neurological findings. But facial palsy was disappeared immediately after myringotomy. We considered that the etiology of this case was neuropraxia of facial nerve in middle ear caused by over pressure of middle ear. PMID:22953110

  15. [Evaluation of total energy expenditure in adult, overweight and free-living subjects. A comparison between two methods: Factorial Method vs SenseWear Armband "Metabolic Holter"]. (United States)

    Giobbi, G


    Evaluation of SenseWear Armband functional and structural characteristics and comparison between TEE value from Factorial Method and Metabolic Holter. The study has involved a homogeneous group of 21 adult, overweight (25BMI30 Kg/m(2)) and free-living subjects, 9 men and 12 women, with an average age of 34.9 +/- 14.5 (20-60 years old). TEE valuation has been performed for each subject by means of Factorial Method and, secondly, through the application of SenseWear Armband (Bodymedia Inc., Pittsburgh, PA, USA). Values recorded by Armband overestimate Factorial values of 14%. The Student's t Test has reported significant results (t = 3.540; p = 0.002). Spearman's Correlation has showed the following values of r = 0.696 and p = 0.001. The analysed methods can't be superimposed because the study has showed a signifi cant difference between the reported values. In spite of all that, Spearman study has highlighted a remarkable statistic relation between the techniques. In conclusion, SWA and FM seem to allow a corresponding diagnosis.

  16. Evaluation of a new methodology to simulate damage and wear of polyethylene hip replacements subjected to edge loading in hip simulator testing. (United States)

    Partridge, Susan; Tipper, Joanne L; Al-Hajjar, Mazen; Isaac, Graham H; Fisher, John; Williams, Sophie


    Wear and fatigue of polyethylene acetabular cups have been reported to play a role in the failure of total hip replacements. Hip simulator testing under a wide range of clinically relevant loading conditions is important. Edge loading of hip replacements can occur following impingement under extreme activities and can also occur during normal gait, where there is an offset deficiency and/or joint laxity. This study evaluated a hip simulator method that assessed wear and damage in polyethylene acetabular liners that were subjected to edge loading. The liners tested to evaluate the method were a currently manufactured crosslinked polyethylene acetabular liner and an aged conventional polyethylene acetabular liner. The acetabular liners were tested for 5 million standard walking cycles and following this 5 million walking cycles with edge loading. Edge loading conditions represented a separation of the centers of rotation of the femoral head and the acetabular liner during the swing phase, leading to loading of the liner rim on heel strike. Rim damage and cracking was observed in the aged conventional polyethylene liner. Steady-state wear rates assessed gravimetrically were lower under edge loading compared to standard loading. This study supports previous clinical findings that edge loading may cause rim cracking in liners, where component positioning is suboptimal or where material degradation is present. The simulation method developed has the potential to be used in the future to test the effect of aging and different levels of severity of edge loading on a range of cross-linked polyethylene materials. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2017. © 2017 Wiley Periodicals, Inc.

  17. Scuba Diving and Kinesiology: Development of an Academic Program (United States)

    Kovacs, Christopher R.; Walter, Daniel


    The use of scuba diving as a recreational activity within traditional university instructional programs has been well established. Departments focusing on kinesiology, physical education, or exercise science have often provided scuba diving lessons as part of their activity-based course offerings. However, few departments have developed an…

  18. Predictors for the development of temporomandibular disorders in scuba divers

    NARCIS (Netherlands)

    Lobbezoo, F.; van Wijk, A.J.; Klinger, M.C.; Ruiz Vicente, E.; van Dijk, C.J.; Eijkman, M.A.J.


    The aim was to determine predictors for the development of complaints of temporomandibular disorders (TMD) in a large sample of Dutch scuba divers who were free of any TMD complaints before they started diving actively. Five-hundred and thirty-six scuba divers (mean ± SD age = 40·4 ± 11·9 years;

  19. [Scuba diving in children: Physiology, risks and recommendations]. (United States)

    Cilveti, R; Osona, B; Peña, J A; Moreno, L; Asensio, O


    The increase in recreational scuba diving in recent years, including children, involves risks and the possibility of accidents. While legislation, conditions and risks of scuba diving are well documented in adults, scientific evidence in scuba diving by children and adolescents is sparse and isolated. Furthermore, existing guidelines and recommendations for adults cannot be transferred directly to children. These circumstances have led to the Group on Techniques of the Spanish Society of Pediatric Pulmonology (SENP) to perform a literature search to review and update the knowledge about scuba diving in children. Physiological adaptations of the body are examined during the dive, as well as the anatomical and physiological characteristics of children that should be taken into account in scuba diving. The most common types of accidents and its causes, as well as the risks of scuba diving practice in children with previous diseases are discussed, along with details of the medical and psychological requirements for scuba diving to be considered in the assessment of child and adolescent. A list of recommendations for scuba diving with compressed air in children is presented by a group of experts. Copyright © 2015 Asociación Española de Pediatría. Published by Elsevier España, S.L.U. All rights reserved.

  20. Physiological and Subjective Responses to Wearing the A/P22P-9(V) helicopter Aircrewman Chemical, Biological Protection Ensemble (United States)


    2. The assembly consists of eight basic components. MK-i Undercoverall 14. The MK-i is a one-piece coverall constructed of a nonwoven nylon fabric...constructed of a nonwoven nylon fabric with a small percentage of viscose rayon. The outside of the garment is treated with a fluorochemical to repel liquids...temperatures was known to produce heat stress. subjects were well-trained on heat-related injuries, their symptoms and remedies . An explanation of heat

  1. Eye Wear (United States)

    Eye wear protects or corrects your vision. Examples are Sunglasses Safety goggles Glasses (also called eyeglasses) Contact ... jobs and some sports carry a risk of eye injury. Thousands of children and adults get eye ...



    ÖZTÜRK, Özmen; Tek, Mustafa; Seven, Hüseyin


    Objective: The design of a diving regulator's mouth-piece is known to increase the risk of a temporomandibular disorder (TMD) in SCUBA divers. The total weight of a diving regulator is reflected directly on the temporomandibular joint (TMJ) causing articular and periarticular problems. In this study, the prevalence of TMD in SCUBA divers having a training for diving certification is investigated. We also aimed to determine the factors that lead to TMD, and clarify the observation that there i...

  3. B-type natriuretic peptide secretion following scuba diving

    DEFF Research Database (Denmark)

    Passino, Claudio; Franzino, Enrico; Giannoni, Alberto


    To examine the neurohormonal effects of a scuba dive, focusing on the acute changes in the plasma concentrations of the different peptide fragments from the B-type natriuretic peptide (BNP) precursor.......To examine the neurohormonal effects of a scuba dive, focusing on the acute changes in the plasma concentrations of the different peptide fragments from the B-type natriuretic peptide (BNP) precursor....

  4. Tooth wear

    Directory of Open Access Journals (Sweden)

    Tušek Ivan


    Full Text Available Tooth wear is the loss of dental hard tissue that was not caused by decay and represents a common clinical problem of modern man. In the etiology of dental hard tissue lesions there are three dominant mechanisms that may act synergistically or separately:friction (friction, which is caused by abrasion of exogenous, or attrition of endogenous origin, chemical dissolution of dental hard tissues caused by erosion, occlusal stress created by compression and flexion and tension that leads to tooth abfraction and microfracture. Wear of tooth surfaces due to the presence of microscopic imperfections of tooth surfaces is clinically manifested as sanding veneers. Tribology, as an interdisciplinary study of the mechanisms of friction, wear and lubrication at the ultrastructural level, has defined a universal model according to which the etiopathogenesis of tooth wear is caused by the following factors: health and diseases of the digestive tract, oral hygiene, eating habits, poor oral habits, bruxism, temporomandibular disorders and iatrogenic factors. Attrition and dental erosion are much more common in children with special needs (Down syndrome. Erosion of teeth usually results from diseases of the digestive tract that lead to gastroesophageal reflux (GER of gastric juice (HCl. There are two basic approaches to the assessment of the degree of wear and dental erosion. Depending on the type of wear (erosion, attrition, abfraction, the amount of calcium that was realised during the erosive attack could be determined qualitatively and quantitatively, or changes in optical properties and hardness of enamel could be recorded, too. Abrasion of teeth (abrasio dentium is the loss of dental hard tissue caused by friction between the teeth and exogenous foreign substance. It is most commonly provoked by prosthetic dentures and bad habits, while its effect depends on the size of abrasive particles and their amount, abrasive particle hardness and hardness of tooth

  5. SCUBA: The Self-Contained Unified Bass Augmenter (United States)

    Cceres, Juan Pablo; Mysore, Gautham J.; Trevio, Jeffrey


    The Self-Contained Unified Bass Augmenter (SCUBA) is a new augmentative OSC (Open Sound Control) controller for the tuba. SCUBA allows new expressive possibilities by adding onboard continuous and discrete sensors to provide user-controlled parametric data for the processing of the instruments natural sound in Pd. SCUBA endows acoustic instruments with parametric control of virtual instruments and provides a means of integrating the output of a virtual instrument with the natural sound of the tuba. The user sends controller data from the augmented tuba interface to the virtual instrument via FSRs (Force-Sensitive Resistors) and buttons mounted on the existing instrument interface. An AVRMini microcontroller converts raw sensor data to OSC (Open Sound Control) messages, which are mapped in Pd to control virtual instrument parameters. Virtual instrument output is integrated into the solo instrument interface via satellite speakers mounted in the bell; this allows for mixing of the instruments natural sound with that of the virtual instrument to create the impression of a single instrument. This integration is the goal of the SCUBA project: by providing a flexible but unified control interface and acoustic output, traditional acoustic instrument interfaces can be augmented and paired with virtual musical instruments. [We would like to thank Michael Gurevich, Max Matthews, Bill Verplank, Pascal Stang, and classmates from Music 250 (Fall 04) for assistance in the realization of this project.

  6. Differences in SCUBA diver motivations based on level of development (United States)

    Sharon L. Todd; Alan R. Graefe; Walter Mann


    This study examined SCUBA divers' level of development in relationship to their motivations to dive. During the fall of 1999,869 divers ranging from beginners to post-experts were surveyed (37% response rate). Respondents ranked 24 motives on a 5-point importance scale. When the data were reduced using factor analysis to tease out major themes, six factors (...

  7. Evaluation of the Draeger LAR V Pure Oxygen Scuba (United States)


    consisting of the basic equipment required by- the swimmer to survive in his opera- tional environ~ment along with his self-contained comunications ...produced a new oxygen scuba nor is a new unit now in the immediate planning. This factor is due in part to management priority and funding considerations

  8. The prevalence of cervical tooth wear in patients with bruxism and other causes of wear. (United States)

    Shah, Punit; Razavi, Sheri; Bartlett, David W


    The aim of this study was to investigate the prevalence of cervical wear lesions in three groups of patients: bruxists, combined tooth wear, and controls. The hypothesis was that those subjects presenting with bruxism were more likely to develop cervical wear lesions. Of 119 subjects, 31 were bruxists with a mean age 48.7 years [standard deviation (SD): 11.6]; 22 had combined wear, aged 43.5 years (14.2); and 66 controls aged 44.9 years (17.0). The clinical appearance of the tooth wear was used to recruit subjects to the bruxist and combined tooth wear groups. Control subjects were randomly selected from those attending for routine dental examination at two general dental practices. A tooth wear index (TWI) was used by two trained examiners to record the severity of wear in each group. There was a statistically significant difference between the controls and both the bruxist and combined tooth wear groups for wear on all surfaces (p < or = 0.001). There was no significant difference between the bruxist and the combined tooth wear group for wear on any surface. There was a statistically significant difference between the control group and both the bruxist and the combined tooth wear group for the severity of cervical wear (p < or = 0.005), but no difference between the bruxist and combined tooth wear groups. There was also no statistical difference in the number of cervical lesions between the groups. In this study, the likely cause of cervical tooth wear was multifactorial.

  9. Microstructure, Mechanical and Abrasive Wear Behavior of 8.0 wt pct Cr White Iron Subjected to Continuous and Cyclic Annealing Treatment (United States)

    Mandal, Siddhartha Sankar; Ghosh, K. S.; Mondal, Dipak Kumar


    Continuous annealing treatment (austenitization for 4 hours followed by furnace cooling) and cyclic annealing treatment (four cycles of austenitization, each of 0.66 hours duration followed by forced air cooling) of 8.0 wt pct Cr white iron samples are undertaken at 1173 K, 1223 K, 1273 K, 1323 K, and 1373 K (900 °C, 950 °C, 1000 °C, 1050 °C, and 1100 °C) as steps of destabilizing the as-cast structure. Continuous annealing results in precipitation of secondary carbides on a matrix containing mainly pearlite, while cyclic annealing treatment causes similar precipitation of secondary carbides on a matrix containing martensite plus retained austenite. On continuous annealing, the hardness falls below the as-cast value (HV 556), while after cyclic annealing treatment there is about 70 pct increase in hardness, i.e., up to HV 960. Decrease in hardness with increasing annealing temperature is quite common after both heat treatments. The as-cast notched impact toughness (4.0 J) is nearly doubled by increasing to 7.0 J after both continuous and cyclic annealing treatment at 1173 K and 1223 K (900 °C and 950 °C). Cyclic annealing treatment gives rise to a maximum notched impact toughness of 10.0 J at 1373 K (1100 °C). Abrasive wear resistance after continuous annealing treatment degrades exhibiting wear loss greater than that of the as-cast alloy. In contrast, samples with cyclic annealing treatment show reasonably good wear resistance, thereby superseding the wear performance of Ni-Hard IV.

  10. Subjectivity

    Directory of Open Access Journals (Sweden)

    Jesús Vega Encabo


    Full Text Available In this paper, I claim that subjectivity is a way of being that is constituted through a set of practices in which the self is subject to the dangers of fictionalizing and plotting her life and self-image. I examine some ways of becoming subject through narratives and through theatrical performance before others. Through these practices, a real and active subjectivity is revealed, capable of self-knowledge and self-transformation. 

  11. Relationship Between Simulated Gap Wear and Generalized Wear of Resin Luting Cements. (United States)

    Tsujimoto, A; Barkmeier, W W; Takamizawa, T; Latta, M A; Miayazaki, M

    The relationship between the simulated gap wear and generalized wear of resin luting cements was investigated. Five resin luting cements, G-Cem LinkForce (GL), Multilink Automix (MA), NX3 Nexus, Panavia V5 (PV), and RelyX Ultimate were evaluated and subsequently subjected to a wear challenge in a Leinfelder-Suzuki (Alabama) wear simulation device. Half of the specimens from each resin luting cement were photo-cured for 40 seconds and the other half were not photo-cured. The simulated gap and generalized wear were generated using a flat-ended stainless steel antagonist. Wear testing was performed in a water slurry of polymethyl methacrylate beads, and the simulated gap and generalized wear were determined using a noncontact profilometer (Proscan 2100) in conjunction with the Proscan and AnSur 3D software. A strong relationship was found between the gap wear and generalized wear simulation models. The simulated gap wear and generalized wear of the resin luting cements followed similar trends in terms of both volume loss and mean depth of wear facets with each curing method. Unlike the simulated gap wear and generalized wear of GL and PV, those of MA, NX, and RU were influenced by the curing method. The results of this study indicate that simulated gap wear of resin luting cements is very similar to simulated generalized wear. In most cases, dual curing appears to ensure greater wear resistance of resin luting cements than chemical curing alone. The wear resistance of some resin luting cements appears to be material dependent and is not influenced by the curing method.

  12. Wear rates of resin composites. (United States)

    Barkmeier, W W; Erickson, R I; Latta, M A; Wilwerding, T M


    SUMMARY A laboratory study was conducted to examine the wear of resin composite materials using a generalized wear simulation model. Ten specimens each of five resin composites (Esthet•X [EX], Filtek Supreme Plus [SP], Filtek Z250 [Z2], Tetric EvoCeram [EC], and Z100 Restorative [Z1]) were subjected to wear challenges of 100,000, 400,000, 800,000, and 1,200,000 cycles. The materials were placed in cylinder-shaped stainless-steel fixtures, and wear was generated using a flat stainless-steel antagonist in a slurry of polymethylmethacrylate beads. Wear (mean facet depth [μm] and volume loss [mm(3)]) was determined using a noncontact profilometer (Proscan 2000) with Proscan and ProForm software. Statistical analysis of the laboratory data using analysis of variance and Tukey's post hoc test showed a significant difference (p<0.05) for mean wear facet depth and volume loss for both the number of cycles and resin composite material. Linear regression analysis was used to develop predictive wear rates and volume loss rates. Linear wear was demonstrated with correlation coefficients (R(2)) ranging from 0.914 to 0.995. Mean wear values (mean facet depth [μm]) and standard deviations (SD) for 1200K cycles were as follows: Z1 13.9 (2.0), Z2 26.7 (2.7), SP 30.1 (4.1), EC 31.8 (2.3), and EX 67.5 (8.2). Volume loss (mm(3)) and SDs for 1200K cycles were as follows: Z1 0.248 (0.036), Z2 0.477 (0.044), SP 0.541 (0.072), EC 0.584 (0.037), and EX 1.162 (0.139). The wear rate (μm) and volume loss rate (mm(3)) per 100,000 cycles for the five resin composites were as follows: wear rate Z1 0.58, EC 1.27, Z2 1.49, SP 1.62, and EX 4.35, and volume loss rate Z1 0.009, EC 0.024, Z2 0.028, SP 0.029, and EX 0.075. The generalized wear model appears to be an excellent method for measuring relative wear of resin composite materials.

  13. Fluoridation and tooth wear in Irish adults.

    LENUS (Irish Health Repository)

    Burke, F M


    The aim of this study was to determine the prevalence of tooth wear in adults in Ireland and its relationship with water fluoridation. The National Survey of Adult Oral Health was conducted in 2000\\/2001. Tooth wear was determined using a partial mouth examination assessing the upper and lower anterior teeth. A total of 2456 subjects were examined. In this survey, increasing levels and severity of tooth wear were associated with ageing. Men were more affected by tooth wear and were more likely to be affected by severe tooth wear than women. It was found that age, and gender were significant predictors of tooth wear (P < 0.01). Overall, there was no significant relationship between fluoridation and tooth wear in this study.

  14. Comparison of two measurement techniques for clinical wear

    DEFF Research Database (Denmark)

    Peters, M C; Delong, R; Pintado, M R


    Clinical wear of restorations is generally evaluated by marginal integrity over time. In this study, both a subjective and an objective method for wear assessment are compared, and the relative advantages and disadvantages of each are considered....

  15. Provisional Crown Dislodgement during Scuba Diving: A Case of Barotrauma


    Meenal Nitin Gulve; Nitin Dilip Gulve


    Changes in ambient pressure, for example, during flying, diving, or hyperbaric oxygen therapy, can lead to barotrauma. Although it may seem that this issue was neglected in dental education and research in recent decades, familiarity with and understanding of these facts may be of importance for dental practitioners. We report the case of a patient who experienced barotrauma involving dislodgement of a provisional crown during scuba diving. Patients who are exposed to pressure changes as a pa...

  16. Scuba diving post-bleomycin therapy: a case report. (United States)

    Gray, Richard N


    Though there are theoretical risks to scuba diving after undergoing chemotherapy with bleomycin, this case report demonstrates that it may be done without obvious injury if one takes adequate precautions. In this case, one year was allowed to elapse prior to a return to diving. Subsequently 52 dives have been accomplished with no observable adverse effects. Studies are recommended to determine what precautions should be instituted.

  17. Asthma and recreational SCUBA diving: a systematic review. (United States)

    Koehle, Michael; Lloyd-Smith, Rob; McKenzie, Don; Taunton, Jack


    Asthma has traditionally been a contraindication to recreational self-contained underwater breathing apparatus (SCUBA) diving, although large numbers of patients with asthma partake in diving. The purpose of this paper is to review all the research relevant to the issue of the safety of asthma in divers. MEDLINE and MDConsult were searched for papers between 1980-2002. Keywords used for the search were 'asthma', 'SCUBA' and 'diving'. Additional references were reviewed from the bibliographies of received articles.A total of fifteen studies were identified as relevant to the area. These included three surveys of divers with asthma, four case series and eight mechanistic investigations of the effect of diving on pulmonary function. The survey data showed a high prevalence of asthma among recreational SCUBA divers, similar to the prevalence of asthma among the general population. There was some weak evidence for an increase in rates of decompression illness among divers with asthma. In healthy participants, wet hyperbaric chamber and open-water diving led to a decrease in forced vital capacity, forced expired volume over 1.0 second and mid-expiratory flow rates. In participants with asymptomatic respiratory atopy, diving caused a decrease in airway conductivity.There is some indication that asthmatics may be at increased risk of pulmonary barotrauma, but more research is necessary. Decisions regarding diving participation among asthmatics must be made on an individual basis involving the patient through informed, shared decision making.

  18. Design and Validation of a Breathing Detection System for Scuba Divers

    Directory of Open Access Journals (Sweden)

    Corentin Altepe


    Full Text Available Drowning is the major cause of death in self-contained underwater breathing apparatus (SCUBA diving. This study proposes an embedded system with a live and light-weight algorithm which detects the breathing of divers through the analysis of the intermediate pressure (IP signal of the SCUBA regulator. A system composed mainly of two pressure sensors and a low-power microcontroller was designed and programmed to record the pressure sensors signals and provide alarms in absence of breathing. An algorithm was developed to analyze the signals and identify inhalation events of the diver. A waterproof case was built to accommodate the system and was tested up to a depth of 25 m in a pressure chamber. To validate the system in the real environment, a series of dives with two different types of workload requiring different ranges of breathing frequencies were planned. Eight professional SCUBA divers volunteered to dive with the system to collect their IP data in order to participate to validation trials. The subjects underwent two dives, each of 52 min on average and a maximum depth of 7 m. The algorithm was optimized for the collected dataset and proved a sensitivity of inhalation detection of 97.5% and a total number of 275 false positives (FP over a total recording time of 13.9 h. The detection algorithm presents a maximum delay of 5.2 s and requires only 800 bytes of random-access memory (RAM. The results were compared against the analysis of video records of the dives by two blinded observers and proved a sensitivity of 97.6% on the data set. The design includes a buzzer to provide audible alarms to accompanying dive buddies which will be triggered in case of degraded health conditions such as near drowning (absence of breathing, hyperventilation (breathing frequency too high and skip-breathing (breathing frequency too low measured by the improper breathing frequency. The system also measures the IP at rest before the dive and indicates with

  19. Design and Validation of a Breathing Detection System for Scuba Divers. (United States)

    Altepe, Corentin; Egi, S Murat; Ozyigit, Tamer; Sinoplu, D Ruzgar; Marroni, Alessandro; Pierleoni, Paola


    Drowning is the major cause of death in self-contained underwater breathing apparatus (SCUBA) diving. This study proposes an embedded system with a live and light-weight algorithm which detects the breathing of divers through the analysis of the intermediate pressure (IP) signal of the SCUBA regulator. A system composed mainly of two pressure sensors and a low-power microcontroller was designed and programmed to record the pressure sensors signals and provide alarms in absence of breathing. An algorithm was developed to analyze the signals and identify inhalation events of the diver. A waterproof case was built to accommodate the system and was tested up to a depth of 25 m in a pressure chamber. To validate the system in the real environment, a series of dives with two different types of workload requiring different ranges of breathing frequencies were planned. Eight professional SCUBA divers volunteered to dive with the system to collect their IP data in order to participate to validation trials. The subjects underwent two dives, each of 52 min on average and a maximum depth of 7 m. The algorithm was optimized for the collected dataset and proved a sensitivity of inhalation detection of 97.5% and a total number of 275 false positives (FP) over a total recording time of 13.9 h. The detection algorithm presents a maximum delay of 5.2 s and requires only 800 bytes of random-access memory (RAM). The results were compared against the analysis of video records of the dives by two blinded observers and proved a sensitivity of 97.6% on the data set. The design includes a buzzer to provide audible alarms to accompanying dive buddies which will be triggered in case of degraded health conditions such as near drowning (absence of breathing), hyperventilation (breathing frequency too high) and skip-breathing (breathing frequency too low) measured by the improper breathing frequency. The system also measures the IP at rest before the dive and indicates with flashing light

  20. Wear in human knees

    Directory of Open Access Journals (Sweden)

    M.L. Wang


    Full Text Available Wear occurs in natural knee joints and plays a pivotal factor in causing articular cartilage degradation in osteoarthritis (OA processes. Wear particles are produced in the wear process and get involved in inflammation of human knees. This review presents progresses in the mechanical and surface morphological studies of articular cartilages, wear particles analysis techniques for wear studies and investigations of human knee synovial fluid in wear of human knees. Future work is also included for further understanding of OA symptoms and their relations which may shed light on OA causes.

  1. The SCUBA-2 Cosmology Legacy Survey: demographics of the 450-μm population

    NARCIS (Netherlands)

    Roseboom, I. G.; Dunlop, J. S.; Cirasuolo, M.; Geach, J. E.; Smail, I.; Halpern, M.; van der Werf, P.; Almaini, O.; Arumugam, V.; Asboth, V.; Auld, R.; Blain, A.; Bremer, M. N.; Bock, J.; Bowler, R. A. A.; Buitrago, F.; Chapin, E.; Chapman, S.; Chrysostomou, A.; Clarke, C.; Conley, A.; Coppin, K. E. K.; Danielson, A. L. R.; Farrah, D.; Glenn, J.; Hatziminaoglou, E.; Ibar, E.; Ivison, R. J.; Jenness, T.; van Kampen, E.; Karim, A.; Mackenzie, T.; Marsden, G.; Meijerink, R.; Michałowski, M. J.; Oliver, S. J.; Page, M. J.; Pearson, E.; Scott, Douglas; Simpson, J. M.; Smith, D. J. B.; Spaans, M.; Swinbank, A. M.; Symeonidis, M.; Targett, T.; Valiante, E.; Viero, M.; Wang, L.; Willott, C. J.; Zemcov, M.


    We investigate the multiwavelength properties of a sample of 450-μm-selected sources from the SCUBA-2 Cosmology Legacy Survey. A total of 69 sources were identified above 4σ in deep SCUBA-2 450-μm observations overlapping the UDS and COSMOS fields and covering 210 arcmin2 to a typical depth of σ450

  2. Constructing safety through “contrast” during training in scuba diving ...

    African Journals Online (AJOL)

    Safety is a very important aspect in scuba diving, as not complying with safety regulations can lead to serious injury or even death. In this article the researchers focused on the discursive construction of safety during training in scuba diving. The research position fell within the field of discursive psychology. The researcher ...

  3. Multiscale Modeling of Wear Degradation

    KAUST Repository

    Moraes, Alvaro


    Cylinder liners of diesel engines used for marine propulsion are naturally subjected to a wear process, and may fail when their wear exceeds a specified limit. Since failures often represent high economical costs, it is utterly important to predict and avoid them. In this work [4], we model the wear process using a pure jump process. Therefore, the inference goal here is to estimate: the number of possible jumps, its sizes, the coefficients and the shapes of the jump intensities. We propose a multiscale approach for the inference problem that can be seen as an indirect inference scheme. We found that using a Gaussian approximation based on moment expansions, it is possible to accurately estimate the jump intensities and the jump amplitudes. We obtained results equivalent to the state of the art but using a simpler and less expensive approach.

  4. Multiscale Modeling of Wear Degradation

    KAUST Repository

    Moraes, Alvaro


    Cylinder liners of diesel engines used for marine propulsion are naturally subjected to a wear process, and may fail when their wear exceeds a specified limit. Since failures often represent high economical costs, it is utterly important to predict and avoid them. In this work [4], we model the wear process using a pure jump process. Therefore, the inference goal here is to estimate: the number of possible jumps, its sizes, the coefficients and the shapes of the jump intensities. We propose a multiscale approach for the inference problem that can be seen as an indirect inference scheme. We found that using a Gaussian approximation based on moment expansions, it is possible to accurately estimate the jump intensities and the jump amplitudes. We obtained results equivalent to the state of the art but using a simpler and less expensive approach.

  5. Multiscale Modeling of Wear Degradation

    KAUST Repository

    Moraes, Alvaro


    Cylinder liners of diesel engines used for marine propulsion are naturally subjected to a wear process, and may fail when their wear exceeds a specified limit. Since failures often represent high economical costs, it is utterly important to predict and avoid them. In this work [4], we model the wear process using a pure jump process. Therefore, the inference goal here is to estimate: the number of possible jumps, its sizes, the coefficients and the shapes of the jump intensities. We propose a multiscale approach for the inference problem that can be seen as an indirect inference scheme. We found that using a Gaussian approximation based on moment expansions, it is possible to accurately estimate the jump intensities and the jump amplitudes. We obtained results equivalent to the state of the art but using a simpler and less expensive approach.

  6. Evaluation of Commercially Available Open Circuit Scuba Regulators. (United States)


    more valid approach for setting performance standards. E. First Stage Performance The performance of the scuba regulator’s first stage is critical to... approach 40 to 50 psig, less than static, the regulator ceases to function in a manner which can effectively support a diver. Con- versely, when a...1 2 65 18 80 -DPT I-N _ - F i gur 21)-,) Dacor acer 60 Breith n,, wor v.;. ept at 000 psi ,mp l-v presur so- A - OO pmg 70- 60- CL z 50- 0 33 66 99

  7. Comparative wear mapping techniques

    DEFF Research Database (Denmark)

    Alcock, J.; Sørensen, Ole Toft; Jensen, S.


    Pin-on-disc tests of tungsten carbide pins against silicon carbide discs were performed and wear rate, mechanism and friction maps constructed. Correlations were observed between the wear mode and the friction of the pin-disc interface, and between the qualitative incidence of disruptive wear mec...

  8. Superior canal dehiscence syndrome associated with scuba diving. (United States)

    Kitajima, Naoharu; Sugita-Kitajima, Akemi; Kitajima, Seiji


    A 28-year-old female diver presented with dizziness and difficulty clearing her left ear whilst scuba diving. Her pure-tone audiometry and tympanometry were normal. Testing of Eustachian tube function revealed tubal stenosis. Video-oculography revealed a predominantly torsional nystagmus while the patient was in the lordotic position. Fistula signs were positive. High-resolution computed tomography (HRCT) of the temporal bone revealed a diagnosis of bilateral superior semicircular canal dehiscence (SCDS). Cervical vestibular-evoked myogenic potential (cVEMP) testing showed that the amplitude of the cVEMP measured from her left ear was larger than that from the right. In electronystagmography (ENG), nose-pinched Valsalva manoeuvres caused eye movements to be mainly directed counterclockwise with a vertical component. Tullio phenomenon was also positive for both ears. SCDS patients tend to be misdiagnosed and misunderstood; common misdiagnoses in these cases are alternobaric vertigo (AV), inner ear barotrauma, and inner-ear decompression sickness. It is difficult to diagnose vertigo attacks after scuba diving as SCDS; however, when the patient develops sound- and/or pressure-induced vertical-torsional nystagmus, HRCT should be conducted to confirm a diagnosis of SCDS.

  9. Negative neurofunctional effects of frequency, depth and environment in recreational scuba diving: the Geneva "memory dive" study. (United States)

    Slosman, D O; De Ribaupierre, S; Chicherio, C; Ludwig, C; Montandon, M-L; Allaoua, M; Genton, L; Pichard, C; Grousset, A; Mayer, E; Annoni, J-M; De Ribaupierre, A


    To explore relationships between scuba diving activity, brain, and behaviour, and more specifically between global cerebral blood flow (CBF) or cognitive performance and total, annual, or last 6 months' frequencies, for standard dives or dives performed below 40 m, in cold water or warm sea geographical environments. A prospective cohort study was used to examine divers from diving clubs around Lac Léman and Geneva University Hospital. The subjects were 215 healthy recreational divers (diving with self-contained underwater breathing apparatus). Main outcome measures were: measurement of global CBF by (133)Xe SPECT (single photon emission computed tomography); psychometric and neuropsychological tests to assess perceptual-motor abilities, spatial discrimination, attentional resources, executive functioning, and memory; evaluation of scuba diving activity by questionnaire focusing on number and maximum depth of dives and geographical site of the diving activity (cold water v warm water); and body composition analyses (BMI). (1) A negative influence of depth of dives on CBF and its combined effect with BMI and age was found. (2) A specific diving environment (more than 80% of dives in lakes) had a negative effect on CBF. (3) Depth and number of dives had a negative influence on cognitive performance (speed, flexibility and inhibition processing in attentional tasks). (4) A negative effect of a specific diving environment on cognitive performance (flexibility and inhibition components) was found. Scuba diving may have long-term negative neurofunctional effects when performed in extreme conditions, namely cold water, with more than 100 dives per year, and maximal depth below 40 m.

  10. Comparative measurement of intraocular pressure by Icare tonometry and Airpuff tonometry in healthy subjects and patients wearing therapeutic soft contact lenses. (United States)

    Anton, Alexandra; Neuburger, Matthias; Böhringer, Daniel; Jordan, Jens F


    The aim of the present study was to compare the measurement of intraocular pressure (IOP) through a therapeutic soft contact lens with the "native" measurement. We additionally investigate whether a rebound tonometer (RT) or non-contact tonometer (NCT) is more suitable to measure IOP through a bandage contact lens. The IOP was determined using each of the two methods, three times successively with (lens measurement) and without (native measurement) a soft contact lens. The Icare tonometer (Icare® TA01i, Icare Finland Oy, 23 subjects) and the Airpuff tonometer (Nidek NT 53OP, Nidek CO., LTD, Hiroishi Gamagori, Aichi, Japan, 16 subjects) were used. We compared the mean values (validity parameter) and standard deviation (precision parameter) of the three individual measurements in each case using the paired t-test. In addition, we conducted a power analysis to estimate the maximum error in the measurement caused by the contact lens (power level set to 0.8). With the Airpuff tonometer we detected no statistically significant between the lens and the native measurement (15.6 ± 2.6 vs. 15.3 ± 2.6 mmHg; p = 0.42). The power analysis revealed that the maximum error caused by the contact lens was 1.2 mmHg. The Icare tonometry, however, trended toward higher values in the contact lens measurements (17.5 ± 4.3 vs. 16.4 ± 3.5 mmHg in the native measurements; p = 0.05). Interestingly, this difference exhibited a statistically significant correlation with the corneal thickness (0.03 mmHg per μm corneal thickness; p = 0.04). The use of NCT and RT for IOP measurement over a soft contact lens is feasible. The accuracy appears to be sufficient for the most common clinical applications.

  11. Polymer wear evaluation

    DEFF Research Database (Denmark)

    Lagerbon, Mikkel; Sivebæk, Ion Marius


    Polymer wear plays an increasing role in manufacturing of machine parts for e.g. medical devices. Some of these have an expected lifetime of five to eight years during which very little wear of the components is acceptable. Too much wear compromises the dosage accuracy of the device and thereby...... the safety of the patients. Prediction of the wear of polymers is complicated by the low thermal conductivity of this kind of material. It implies that any acceleration of testing conditions by increased contact pressure and/or sliding velocity will make the polymer fail due to exaggerated heat buildup....... This is not the kind of wear observed in medical devices. In the present work a method was developed capable of evaluating the wear progression in polymer-polymer contacts. The configuration of the setup is injection moulded specimens consisting of an upper part having a toroid shape and a lower flat part. The sliding...

  12. Provisional Crown Dislodgement during Scuba Diving: A Case of Barotrauma

    Directory of Open Access Journals (Sweden)

    Meenal Nitin Gulve


    Full Text Available Changes in ambient pressure, for example, during flying, diving, or hyperbaric oxygen therapy, can lead to barotrauma. Although it may seem that this issue was neglected in dental education and research in recent decades, familiarity with and understanding of these facts may be of importance for dental practitioners. We report the case of a patient who experienced barotrauma involving dislodgement of a provisional crown during scuba diving. Patients who are exposed to pressure changes as a part of their jobs or hobbies and their dentists should know the causes of barotrauma. In addition, the clinician must be aware of the possible influence of pressure changes on the retention of dental components.

  13. Estimating the risk of a scuba diving fatality in Australia. (United States)

    Lippmann, John; Stevenson, Christopher; McD Taylor, David; Williams, Jo


    There are few data available on which to estimate the risk of death for Australian divers. This report estimates the risk of a scuba diving fatality for Australian residents, international tourists diving in Queensland, and clients of a large Victorian dive operator. Numerators for the estimates were obtained from the Divers Alert Network Asia-Pacific dive fatality database. Denominators were derived from three sources: Participation in Exercise, Recreation and Sport Surveys, 2001-2010 (Australian resident diving activity data); Tourism Research Australia surveys of international visitors to Queensland 2006-2014 and a dive operator in Victoria 2007-2014. Annual fatality rates (AFR) and 95% confidence intervals (95% CI) were calculated using an exact binomial test. Estimated AFRs were: 0.48 (0.37-0.59) deaths per 100,000 dives, or 8.73 (6.85-10.96) deaths per 100,000 divers for Australian residents; 0.12 (0.05-0.25) deaths per 100,000 dives, or 0.46 (0.20-0.91) deaths per 100,000 divers for international visitors to Queensland; and 1.64 (0.20-5.93) deaths per 100,000 dives for the dive operator in Victoria. On a per diver basis, Australian residents are estimated to be almost twenty times more likely to die whilst scuba diving than are international visitors to Queensland, or to lower than fourfold on a per dive basis. On a per dive basis, divers in Victoria are fourteen times more likely to die than are Queensland international tourists. Although some of the estimates are based on potentially unreliable denominator data extrapolated from surveys, the diving fatality rates in Australia appear to vary by State, being considerably lower in Queensland than in Victoria. These estimates are similar to or lower than comparable overseas estimates, although reliability of all such measurements varies with study size and accuracy of the data available.

  14. Energetic aspects of boring tools wear

    Directory of Open Access Journals (Sweden)

    Lazarová Edita


    Full Text Available In the process of rock desintegration a boring tool is subjected to the wear. From a viewpoint of the bit wear, changes on the contact of operating tool with rock at its one-shot and rerun load or overload by external forces are technically significant. Theis change results in the degradation of bit working properties and the output of desintegration also decreases. In the major part of cases, together with the bit wear, the contact area of a tool with a rock massifs enhanced and this fact causes an increase of fines (dust creation during the desintegration. The wear is always connected with a friction, forces action, deformation, damage, and the increased mechanical work consumption. As to energetic aspects of bit wear, the wear was observed as a function of bore length and in the most of cases as a dependence of the operating time. A linear dependence between the wear intensity (bit wear per unit of bore length and the specific energy of desintegration (energy consumed per volume unit of desintegrated rock was experimentally verified. Thus, the changes of bit wear can be implicitly observed by monitoring the specific energy. At the same time, the specific energy is a function of input parameters of the desintegration process and in the field of applicable external forces it shows an extreme (minimum. Therefore, the specific energy is useful for the extreme optimisation of the rock desintegration process from the viewpoint of the bit wear. It was mathematically proven that the tool output at the desintegration exponentially decreases with the amount of work consumed in the rock desintegration. The derivation of this knowledge comes out from the Krendelev equation.

  15. Nanoclay-Reinforced Glass-Ionomer Cements: In Vitro Wear Evaluation and Comparison by Two Wear-Test Methods

    Directory of Open Access Journals (Sweden)

    Muhammad A. Fareed


    Full Text Available Glass ionomer cement (GIC represents a major transformation in restorative dentistry. Wear of dental restoratives is a common phenomenon and the determination of the wear resistance of direct-restorative materials is a challenging task. The aim of this paper was to evaluate the wear resistance of novel glass ionomer cement by two wear-test methods and to compare the two wear methods.The wear resistance of a conventional glass ionomer cement (HiFi Advanced Health Care Kent, UK and cements modified by including various percentages of nanoclays (1, 2 and 4 wt % was measured by a reciprocating wear test (ball-on-flat and Oregon Health and Sciences University’s (OHSU wear simulator. The OHSU wear simulation subjected the cement specimens to three wear mechanisms, namely abrasion, three-body abrasion and attrition using a steatite antagonist. The abrasion wear resulted in material loss from GIC specimen as the steatite antagonist forced through the exposed glass particles when it travelled along the sliding path.The hardness of specimens was measured by the Vickers hardness test. The results of reciprocation wear test showed that HiFi-1 resulted in the lowest wear volume 4.90 (0.60 mm3 (p < 0.05, but there was no significant difference (p > 0.05 in the wear volume in comparison to HiFi, HiFi-2 and HiFi-4. Similarly, the results of OHSU wear simulator showed that the total wear volume of HiFi-4 1.49 (0.24 was higher than HiFi-1 and HiFi-2. However, no significant difference (p > 0.05 was found in the OHSU total wear volume in GICs after nanoclay incorporation. The Vickers hardness (HV of the nanoclay-reinforced cements was measured between 62 and 89 HV. Nanoclay addition at a higher concentration (4% resulted in higher wear volume and wear depth. The total wear volumes were less dependent upon abrasion volume and attrition volume. The total wear depths were strongly influenced by attrition depth and to some extent by abrasion depth. The addition of

  16. Recreational scuba diving: negative or positive effects of oxidative and cardiovascular stress? (United States)

    Perovic, Antonija; Unic, Adriana; Dumic, Jerka


    Environmental conditions and increased physical activity during scuba diving are followed by increased production of free radicals and disturbed redox balance. Redox balance disorder is associated with damage of cellular components, changes of cellular signaling pathways and alterations of gene expression. Oxidative stress leads to increased expression of sirtuins (SIRTs), molecules which play an important role in the antioxidant defense, due to their sensitivity to the changes in the redox status and their ability to regulate redox homeostasis. These facts make SIRTs interesting to be considered as molecules affected by scuba diving and in that sense, as potential biomarkers of oxidative status or possible drug targets in reduction of reactive oxygen species (ROS) accumulation. In addition, SIRTs effects through currently known targets make them intriguing molecules which can act positively on health in general and whose expression can be induced by scuba diving.A demanding physical activity, as well as other circumstances present in scuba diving, has the greatest load on the cardiovascular function (CV). The mechanisms of CV response during scuba diving are still unclear, but diving-induced oxidative stress and the increase in SIRTs expression could be an important factor in CV adaptation. This review summarizes current knowledge on scuba diving-induced oxidative and CV stress and describes the important roles of SIRTs in the (patho)physiological processes caused by the redox balance disorder.


    Directory of Open Access Journals (Sweden)

    Hüseyin Metin ERTUNÇ


    Full Text Available In this study, wear mechanisms on cutting tools, especially for the drill bits, during the cutting operation have been investigated. As the importance of full automation in industry has gained substantial importance, tool wear condition monitoring during the cutting operation has been the subject of many investigators. Tool condition monitoring is very crucial in order to change the tool before breakage. Because tool breakage can cause considerable economical damage to both the machine tool and workpiece. In this paper, the studies on the monitoring of drill bit wear in literature have been introduced; the direct/indirect techniques used and sensor fusion techniques have been summarized. The methods which were proposed to determine tool wear evolution as processing the sensor signals collected have been provided and their references have been given for detailed information.

  18. Flying after diving: in-flight echocardiography after a scuba diving week. (United States)

    Cialoni, Danilo; Pieri, Massimo; Balestra, Costantino; Marroni, Alessandro


    Flying after diving may increase decompression sickness risk (DCS), but strong evidence indicating minimum preflight surface intervals (PFSI) is missing. On return flights after a diving week on a live-aboard, 32 divers were examined by in-flight echocardiography with the following protocol: 1) outgoing flight, no previous dive; 2) during the diving week; 3) before the return flight after a 24-h PFSI; and 4) during the return flight. All divers completed similar multiple repetitive dives during the diving week. All dives were equivalent as to inert gas load and gradient factor upon surfacing. No bubbles in the right heart were found in any diver during the outgoing flight or at the preflight control after a 24-h PFSI following the diving week. A significant increase in the number and grade of bubbles was observed during the return flight. However, bubbles were only observed in 6 of the 32 divers. These six divers were the same ones who developed bubbles after every dive. Having observed a 24-h preflight interval, the majority of divers did not develop bubbles during altitude exposure; however, it is intriguing to note that the same subjects who developed significant amounts of bubbles after every dive showed equally significant bubble grades during in-flight echocardiography notwithstanding a correct PFSI. This indicates a possible higher susceptibility to bubble formation in certain individuals, who may need longer PFSI before altitude exposure after scuba diving.

  19. Patient comfort following thirty minutes of lens wear: piggy-back versus conventional rigid-lens wear

    Directory of Open Access Journals (Sweden)

    W. D.H. Gillan


    Full Text Available Discomfort when wearing contact lenses, especially rigid contact lenses, is a common complaint amongst neophyte as well as experienced contact lens wearers. Wearing a piggy-back system of contact lenses has been shown to improve comfort and wearing time, especially in keratoconic subjects. Twenty two normal subjects wore a rigid lens or a piggy-back system of lenses for thirty minutes and after a thirty minute break swopped the mode of lens wear and wore the second modality for a thirty minute period. This study suggests that a piggy-back lens system provides improved comfort compared to wearing a rigid lens on its own. The order of lens wear might, however, influence the perceived comfort.

  20. The prevalence of oro-facial barotrauma among scuba divers. (United States)

    Yousef, Mohammed K; Ibrahim, Maria; Assiri, Abeer; Hakeem, Abdulaziz


    Barotrauma is a physical injury that results from ambient pressure changes during flying, diving or hyperbaric oxygen therapy. The aim of this study was to assess the prevalence of oro-facial barotrauma among a sample of scuba divers in Jeddah, Saudi Arabia. Data for the study were collected through a self-reported questionnaire that was distributed to 166 divers. The questionnaire was divided into two parts, in which the first part contained demographic data and the second part consists of multiple choice questions and a few open-ended questions discussing the different signs and symptoms of orofacial barotraumas. One-hundred-and-sixty-three divers responded. The most frequent symptoms during diving were dry mouth (51.9%), followed by clenching (32.5%) and temporomandibular joint (TMJ) pain (19.5%), while the most frequent symptoms after diving were dry mouth (22.7%) followed by clenching and facial pain (16.9%). Clenching and dry mouth were common findings but are temporary in nature and do not warrant any dental intervention. TMJ and facial pain were also reported but were temporary. The use of commercial mouthpieces during diving may be related to more symptoms when compared with customized types.

  1. Assessment of wear facets produced by the ACTA wear machine

    DEFF Research Database (Denmark)

    Benetti, Ana R; Larsen, Liselotte; Dowling, Adam H


    an assessment of the potential of the experimental RBC formulations for clinical usage. CONCLUSION: The 3D technique allowed for the assessment of mean maximum wear depth and mean total volumetric wear which enables tribological analyses of the wear facet and therefore the wear mechanisms operative. Employing...... the 2D profile technique ranks RBC materials in terms of in-vitro wear performance. CLINICAL SIGNIFICANCE: Confidence in the wear volume measurements can only be achieved if the wear facet is analysed with sufficient resolution using a 3D digital measurement technique. However, the employment of 2D...

  2. Nitric oxide-related endothelial changes in breath-hold and scuba divers. (United States)

    Theunissen, S; Guerrero, F; Sponsiello, N; Cialoni, D; Pieri, M; Germonpré, P; Obeid, G; Tillmans, F; Papadopoulou, V; Hemelryck, W; Marroni, A; De Bels, D; Balestra, C


    Scuba and breath-hold divers are compared to investigate whether endothelial response changes are similar despite different exposure(s) to hyperoxia. 14 divers (nine scuba and five breath-holding) performed either one scuba dive (25m/25 minutes) or successive breath-hold dives at a depth of 20 meters, adding up to 25 minutes of immersion time in a diving pool. Flow-mediated dilation (FMD) was measured using echography. Peripheral post-occlusion reactive hyperemia (PORH) was assessed by digital plethysmography and plasmatic nitric oxide (NO) concentration using a nitrate/nitrite colorimetric assay kit. The FMD decreased in both groups. PORH was reduced in scuba divers but increased in breath-hold divers. No difference in circulating NO was observed for the scuba group. Opposingly, an increase in circulating NO was observed for the breath-hold group. Some cardiovascular effects can be explained by interaction between NO and superoxide anion during both types of diving ending to less NO availability and reducing FMD. The increased circulating NO in the breath-hold group can be caused by physical exercise. The opposite effects found between FMD and PORH in the breath-hold group can be assimilated to a greater responsiveness to circulating NO in small arteries than in large arteries.


    African Journals Online (AJOL)

    using TiN .coated K20 cemented carbide tool inserts to monitor the tool wear. In the early research, tool wear ... deformation, crack initiation, crack propagation and chipping. Such changes in material behavior will ... the coated carbide experienced rapid tool wear (up to a flank wear land of 0.11 Smm), followed by a slow.

  4. Friction, Fretting and Wear: Emerging Materials and Technologies

    Indian Academy of Sciences (India)

    wear, erosion, galling, scuffing and damage. Though these issues have been ... applications ranging from pharmaceuticals, dental implants, mining, transportation, space and nuclear medicine underlines the ... of the mechanical behaviour of solids subjected to erosion, abrasion, fretting, fatigue, impact and wear caused by ...

  5. Growing Evidence about the Relationship between Vessel Dissection and Scuba Diving

    Directory of Open Access Journals (Sweden)

    Simona Brajkovic


    Full Text Available Carotid and vertebral artery dissection are relatively frequent and risky conditions. In the last decade, different patients with extracranial (and in 1 case also intracranial dissections associated with the practice of scuba diving were reported. The connection between the two conditions has not been fully explained so far. In the present article, we report the case of a patient presenting with Claude Bernard-Horner syndrome and homolateral XII cranial nerve palsy, manifesting a few days after diving in the cold water of a lake. The patient ended up having internal carotid artery dissection associated with the formation of a pseudoaneurysm. Here, we offer a summary of all cases reported in the literature about scuba diving and arterial dissection, and provide a critical discussion about which scuba diving-related factors can trigger the dissection of cervical vessels.

  6. Suitability Analysis For Scuba Diving To Develop Marine Tourism At Saebus Island, East Java, Indonesia (United States)

    Wijaya, Putranto; Putra, Tri; Hidayat, Fatra; Levraeni, Chandra; Rizmaadi, Mada; Ambariyanto, Ambariyanto


    Indonesian government currently has policies to improve the performance of the tourism sector, including marine tourism. One of the attractions of marine tourism is the coral ecosystem especially through scuba diving activities. The purpose of this study was to determine the suitability of the coral ecosystem on Saebus Island, East Java, to find appropriate locations for scuba diving activities. Purposive samplings were done around the island to determine four stations which will be assessed through suitability analysis. Tourism Suitability Index was used to assess all stations for scuba diving activities. The result showed that all four stations were categorized as very suitable with the score: 85%, 85%, 85% and 83%, respectively. Several aspects that need to be improved and anticipated for diving at all stations are coral coverage and water current. These results suggest that there are several spots around Saebus Island that are suitable for diving site, and can be promoted as marine tourism destination.

  7. Exercise intensity inferred from air consumption during recreational scuba diving. (United States)

    Buzzacott, Peter; Pollock, Neal W; Rosenberg, Michael


    Episodic exercise is a risk factor for acute cardiac events and cardiac complications are increasingly recognized in fatalities during recreational scuba diving. What is not known is the exercise intensity involved in typical recreational diving. This study used pre- to post-dive gas cylinder pressure drop to estimate air consumption and, from that, exercise intensity during recreational dives. Dive profiles were captured electronically and divers self-reported cylinder pressure changes, perceived workload, thermal status and any problems during dives. Mean surface air consumption (SAC) rate per kg body weight and mean exercise intensity (reported in metabolic equivalents, MET multiples of assumed resting metabolic rate of 3.5 mL·kg⁻¹·min⁻¹) were then estimated. Data are reported as mean ± standard deviation. A total of 959 recreational air dives (20 ± 9 metres' sea water maximum depth; 50 ± 12 min underwater time) by 139 divers (42 ± 10 y age; 11 ± 10 y of diving; 12% smokers; 73% male) were monitored. Problems were reported with 129/959 dives: buoyancy (45%), equalization (38%), rapid ascent (10%), vertigo (5%) and other (2%). Assuming a 10% overestimate due to cylinder cooling and uncontrolled gas loss, the estimated exercise intensity associated with monitored dives was 5 ± 1 MET. Mean ± 2SD, or 7 MET, captures the effort associated with the vast majority of dives monitored. Our estimates suggest that uncomplicated recreational dives require moderate-intensity energy expenditure to complete, with a 7-MET capacity generally adequate. Higher levels of aerobic fitness are still strongly recommended to ensure ample reserves. Further research is needed to quantify energetic demands of recreational diving during both typical and emergent events in both experienced and less experienced divers.

  8. Law and the Wearing of Religious Symbols: European Bans on the Wearing of Religious Symbols in Education (United States)

    Howard, Erica


    Written in accessible language, Law and the Wearing of Religious Symbols is a comprehensive analysis of a topical subject that is being widely debated across Europe. The book provides an overview of emerging case law from the European Court of Human Rights as well as from national courts and equality bodies in European countries on the wearing of…

  9. Managing the cryogenic systems of SCUBA-2 for long term operation (United States)

    Cookson, Jamie L.; Bintley, Dan


    SCUBA-2 has been operational on JCMT producing excellent science for almost 5 years. We describe the strategy and methods that we have evolved to keep one of the world's first "dry dilution refrigerators" and the other cryogenic systems working effectively at the summit of Mauna Kea, keeping the instrument functioning at peak efficiency for extended periods (over 12 months at a time), with minimum downtime. We discuss new plans to reduce day-to-day operational costs and to add remote management of the gas handling systems, as we look to the future and envisage another ten years of SCUBA-2 science.

  10. Simulated Wear of Self-Adhesive Resin Cements. (United States)

    Takamizawa, T; Barkmeier, W W; Latta, M A; Berry, T P; Tsujimoto, A; Miyazaki, M


    One of the primary areas of concern with luting agents is marginal gap erosion and attrition. The purpose of this laboratory study was to evaluate bulk and marginal slit (gap) generalized wear of self-adhesive resin cements. Three self-adhesive resin cements were used in this study: G-CEM LinkAce (LA), Maxcem Elite (ME), and RelyX Unicem2 Automix (RU). A custom stainless-steel fixture with a cavity 4.5 mm in diameter and 4 mm deep was used for simulated generalized (bulk) wear. For simulated marginal gap wear, a two-piece stainless-steel custom fixture was designed with a slit (gap) 300 μm wide and 3 mm in length. For both wear models, 20 specimens each for each of the three adhesive cements were made for both light-cure and chemical-cure techniques. The cured cements were polished with a series of carbide papers to a 4000-grit surface and subjected to 100,000 cycles using the slit (gap) wear model and 400,000 cycles for generalized (bulk) wear in a Leinfelder-Suzuki (Alabama machine) wear simulator (maximum load of 78.5 N). Flat-ended stainless-steel antagonists were used in a water slurry of poly(methylmethacrylate) beads for simulation of generalized contact-free area wear with both wear models. Before and after the wear challenges, the specimens were profiled with a Proscan 2100 noncontact profilometer, and wear (volume loss [VL] and mean facet depth [FD]) was determined using AnSur 3D software. Two-way analysis of variance (ANOVA) and Tukey post hoc tests were used for data analysis for the two wear models. Scanning electron microscopy (SEM) was used to examine polished surfaces of the resin cements and the worn surfaces after the wear challenges. The two-way ANOVA of VL using the generalized (bulk) wear model showed a significant effect among the three resin cement materials for the factor of resin cement (pcement and cure method (pcement (pcement and cure method (pcements and the resultant effect of the wear challenges. The worn surfaces of each cement were

  11. The Devil Wears Prada

    African Journals Online (AJOL)


    The film is based on the book. The Devil Wears Prada written by Lauren Weisberger, ... image and power driven industry that is haute couture and fashion today. Although Andrea's experience is the main ... creations not fit even for Halloween, designer and brand name jewellery and other fashion accessories. Anything from ...

  12. Comparative wear mapping techniques

    DEFF Research Database (Denmark)

    Alcock, J.; Sørensen, Ole Toft; Jensen, S.


    Pin surfaces were analysed by laser profilometry. Two roughness parameters, R(a) and the fractal dimension, were investigated as a first step towards methods of quantitative wear mechanism mapping. Both parameters were analysed for their relationship to the severity and prevalence of a mechanism....

  13. Temporomandibular disorders in scuba divers-an increased risk during diving certification training. (United States)

    Oztürk, Ozmen; Tek, Mustafa; Seven, Hüseyin


    The design of a diving regulator's mouthpiece increases the risk of a temporomandibular disorder (TMD) in scuba divers. The total weight of a diving regulator is reflected directly on the temporomandibular joint, causing articular and periarticular disorders. In the current study, the prevalence of TMD in scuba divers triggered during diving certification training is investigated. We also aimed to determine the factors that lead to TMD during diving training and clarify the observation that there is an increased incidence of TMD in inexperienced divers. The study was held between 2006 and 2011. Ninety-seven divers were referred with the complaint of pain around temporomandibular area. The divers were classified according to their diving experience. Symptoms and signs of TMD were graded. Fourteen divers were diagnosed with TMD. Temporomandibular disorder was seen more frequently in inexperienced divers than in experienced divers (P = 0.0434). The most prevalent symptom was an increased effort for mouthpiece gripping. Temporomandibular joint tenderness and trigger point activation were the mostly seen physical signs. Thirteen divers had an improvement with therapy. The increased effort for stabilizing the mouthpiece is a recognized factor in TMD development. Attention must be paid to an association of scuba diving with TMDs, especially in inexperienced divers having a scuba certification training.

  14. Construction of Tests in the Cognitive and Psychomotor Domains for Skin and Scuba Diving. (United States)

    McCarthy, Jean

    The fundamental purposes of this study were to develop mastery tests in the cognitive and psychomotor domains for skin and scuba diving and to establish validity and reliability for the tests. A table of specifications was developed for each domain, and a pilot study refined the initial test batteries into their final form. In the main study,…

  15. Contrast sensitivity of air-breathing nonprofessional scuba divers at a depth of 40 meters

    NARCIS (Netherlands)

    Schellart, N. A.


    Photopic contrast sensitivity of air-breathing scuba divers was measured with a translucent test pattern at depths up to 40 m. The pattern was composed of sine wave gratings with spatial frequency and contrast changing logarithmically. The spatial transfer characteristics were measured at various

  16. Katayama fever in scuba divers - A report of 3 cases | Evans | South ...

    African Journals Online (AJOL)

    Katayama fever or acute schistosomiasis probably occurs more commonly than is recorded. Interviews with a 3-man scuba diving team who had had contact with a large dam in an ·endemic area of the eastern Transvaal Lowveld at the same time and contact area on the same day during late summer of 1986 are discussed.

  17. Correction for adiabatic effects in lethe calculated instantaneous gas consumption of scuba dives

    NARCIS (Netherlands)

    Schellart, Nico A. M.; Le Péchon, Jean-Claude


    Introduction: In scuba-diving practice, instantaneous gas consumption is generally calculated from the fall in cylinder pressure without considering the effects of water temperature (heat transfer) and adiabatic processes. We aimed to develop a simple but precise method for calculating the

  18. Who is the Scuba Diver that visits Sodwana Bay and why ...

    African Journals Online (AJOL)

    Understanding the travel motives of scuba divers will benefit dive operations and destinations in developing the most appropriate product, improving the services offered and creating more effective promotional activities that will ultimately lead to a competitive advantage. The purpose of this research was to understand the ...

  19. Reducing dropout of contact lens wear with Biotrue multipurpose solution

    Directory of Open Access Journals (Sweden)

    Rah MJ


    Full Text Available Marjorie J Rah, Mohinder M Merchea, Marianne Q DoktorBausch & Lomb Incorporated, Rochester, NY, USAPurpose: To evaluate whether the use of Biotrue multipurpose solution (MPS could significantly reduce the likelihood with which patients drop out of using daily wear contact lenses (CLs amongst 18–44-year-old frequent replacement CL wearers.Methods: Daily wear CL subjects habitually using MPSs (other than Biotrue MPS who reported an intent to imminently drop out of CL wear because of comfort and dryness complaints were recruited to participate in this investigation. Subjects were switched to Biotrue MPS and continued to use habitual CL types with the new MPS for 2 weeks. Subjects completed an online satisfaction questionnaire at baseline and after 2 weeks to assess the change in symptoms and the intent to drop out of CL wear. Six months after completion of the initial study, a follow-up survey was administered to a subset of the initial participants.Results: A total of 153 daily wear (silicone hydrogel and hydrogel subjects completed this 2-week study with Biotrue MPS. When measuring those with the highest propensity to drop out of lens wear (n=93 after switching to Biotrue MPS, 90% of subjects significantly reduced their likelihood of dropping out of CL wear (P<0.0001. Online interviews were conducted with 73 of the study participants 6 months after completion of the initial study. A total of 93% of participants responded that they were still wearing CLs at least once per week. Of the 7% of respondents who were not currently wearing lenses 6 months after the initial study, two had dropped out of lens wear completely, and three still wore lenses less than once per week.Conclusion: Patients intending to drop out of CL wear due to discomfort and dryness significantly reduced their propensity of discontinuing lens wear following use of Biotrue MPS. Six months after completion of the study, 93% of patients were still wearing CLs at least once per

  20. A Review of SCUBA Diving Impacts and Implication for Coral Reefs Conservation and Tourism Management


    Zainal Abidin Siti Zulaiha; Mohamed Badaruddin


    Dive tourism has become important in term of magnitude and significantly contributes to regional economies. Nevertheless, in the absence of proper controls and enforcement, unplanned tourism growth has caused environmental degradation which undermines the long-term sustainability of the tourism industry. The purpose of this paper is to explore factors that contribute to the SCUBA diving impacts on coral and fish communities. This paper explains the causes of a certain event, validating the pr...

  1. The perceived value of scuba diving tourists at a marina destination / Kiéra Seymour.


    Seymour, Kiéra Danielle


    Tourism activities set in coastal and marine environments have evolved far beyond the traditional passive leisure experiences of the classic resort holiday. While the traditional beach holiday remains a contemporary mass tourism phenomenon. Marine tourism now extends far beyond beach activities to a wide spread spectrum of activities including scuba diving with over 20 million certified divers worldwide. The tourism product carries both the characteristics of the service product and the chara...

  2. Effects of recreational scuba diving on Mediterranean fishes: evidence of involuntary feeding?

    Directory of Open Access Journals (Sweden)



    Full Text Available Despite a large body of literature assessing the impacts of recreational scuba diving on marine habitats, little attention has been paid to the potentially harmful effects this has on fishes. The aim of this study was the assessment of the immediate response of different fish species to divers’ activities. A decrease of fishes’ natural diffidence towards divers is shown, probably due to an enhanced availability of their prey as a result of divers’ contacts with the substrate.

  3. Description of an eye barotrauma in scuba diving with clinical discussion

    Directory of Open Access Journals (Sweden)

    Pedro Barreiros


    Full Text Available In this paper we report and discuss a scuba diving accident caused by compression of the mask at a depth of 9.1 m resulting in conjunctiva haemorrhage of both eyes in a 21-year-old male. After five weeks and benefiting from immediate post-accident medical attention and medication followed by ophthalmologic examinations the patient recovered with no chronic effects neither in vision nor in the eyes.

  4. Wear of polymers and composites

    CERN Document Server

    Abdelbary, Ahmed


    In the field of tribology, the wear behaviour of polymers and composite materials is considered a highly non-linear phenomenon. Wear of Polymers and Composites introduces fundamentals of polymers and composites tribology. The book suggests a new approach to explore the effect of applied load and surface defects on the fatigue wear behaviour of polymers, using a new tribometer and thorough experiments. It discusses effects of surface cracks, under different static and cyclic loading parameters on wear, and presents an intelligent algorithm, in the form of a neural network, to map the relations

  5. Friction and wear calculation methods

    CERN Document Server

    Kragelsky, I V; Kombalov, V S


    Friction and Wear: Calculation Methods provides an introduction to the main theories of a new branch of mechanics known as """"contact interaction of solids in relative motion."""" This branch is closely bound up with other sciences, especially physics and chemistry. The book analyzes the nature of friction and wear, and some theoretical relationships that link the characteristics of the processes and the properties of the contacting bodies essential for practical application of the theories in calculating friction forces and wear values. The effect of the environment on friction and wear is a

  6. Mechanical modelling of tooth wear. (United States)

    Karme, Aleksis; Rannikko, Janina; Kallonen, Aki; Clauss, Marcus; Fortelius, Mikael


    Different diets wear teeth in different ways and generate distinguishable wear and microwear patterns that have long been the basis of palaeodiet reconstructions. Little experimental research has been performed to study them together. Here, we show that an artificial mechanical masticator, a chewing machine, occluding real horse teeth in continuous simulated chewing (of 100 000 chewing cycles) is capable of replicating microscopic wear features and gross wear on teeth that resemble wear in specimens collected from nature. Simulating pure attrition (chewing without food) and four plant material diets of different abrasives content (at n = 5 tooth pairs per group), we detected differences in microscopic wear features by stereomicroscopy of the chewing surface in the number and quality of pits and scratches that were not always as expected. Using computed tomography scanning in one tooth per diet, absolute wear was quantified as the mean height change after the simulated chewing. Absolute wear increased with diet abrasiveness, originating from phytoliths and grit. In combination, our findings highlight that differences in actual dental tissue loss can occur at similar microwear patterns, cautioning against a direct transformation of microwear results into predictions about diet or tooth wear rate. © 2016 The Author(s).

  7. Cerebellar infarction presenting as inner ear decompression sickness following scuba diving: a case report. (United States)

    Gempp, E; Louge, P; Soulier, B; Alla, P


    Inner ear decompression sickness following scuba diving is not uncommon and the characteristic features of this disorder are acute peripheral vestibular syndrome, sometimes associated with cochlear signs, requiring urgent hyperbaric oxygen therapy. Cerebellar infarction can also mimic isolated peripheral vestibulopathy. The authors report the case of a 47-year-old man in good general health admitted with acute left vestibular dysfunction suggestive of inner ear decompression sickness 6 hours after scuba diving. Normal videonystagmography and delayed onset of occipital headache finally led to brain MRI that confirmed the presence of recent ischaemic infarction in the territory of the medial branch of the posterior inferior cerebellar artery. Complementary investigations revealed the presence of a patent foramen ovale with atrial septal aneurysm. No underlying atherosclerotic disease or clotting abnormalities were observed. Cerebellar infarction can present clinically with features of inner ear decompression sickness following scuba diving. An underlying air embolism mechanism cannot be excluded, particularly in patients with a large right-to-left circulatory shunt and no other cardiovascular risk factors. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  8. SCUBA-2 follow-up of Herschel-SPIRE observed Planck overdensities (United States)

    MacKenzie, Todd P.; Scott, Douglas; Bianconi, Matteo; Clements, David L.; Dole, Herve A.; Flores-Cacho, Inés; Guery, David; Kneissl, Ruediger; Lagache, Guilaine; Marleau, Francine R.; Montier, Ludovic; Nesvadba, Nicole P. H.; Pointecouteau, Etienne; Soucail, Genevieve


    We present SCUBA-2 follow-up of 61 candidate high-redshift Planck sources. Of these, 10 are confirmed strong gravitational lenses and comprise some of the brightest such submm sources on the observed sky, while 51 are candidate proto-cluster fields undergoing massive starburst events. With the accompanying Herschel-Spectral and Photometric Imaging Receiver observations and assuming an empirical dust temperature prior of 34^{+13}_{-9} K, we provide photometric redshift and far-IR luminosity estimates for 172 SCUBA-2-selected sources within these Planck overdensity fields. The redshift distribution of the sources peak between a redshift of 2 and 4, with one-third of the sources having S500/S350 > 1. For the majority of the sources, we find far-IR luminosities of approximately 1013 L⊙, corresponding to star formation rates of around 1000 M⊙ yr-1. For S850 > 8 mJy sources, we show that there is up to an order of magnitude increase in star formation rate density and an increase in uncorrected number counts of 6 for S850 > 8 mJy when compared to typical cosmological survey fields. The sources detected with SCUBA-2 account for only approximately 5 per cent of the Planck flux at 353 GHz, and thus many more fainter sources are expected in these fields.

  9. A rare case of a scuba diver's death due to propeller injuries of a desalination pump. (United States)

    Perilli, G; Di Battista, B; Montana, A; Pavia, J; Cauchi, S; Zerafa, N M; Pomara, C


    Water skiing, boat racing, skin and scuba diving, as well as pleasure boat cruising are becoming increasingly popular hobbies. As a result, the incidence of injuries secondary to motor propellers is becoming more frequent. Injuries by propellers, amputation, death by drowning, and bleeding are rare reported events in forensic literature. The most common circumstances surrounding boat-propeller-related injuries are concerned with getting into or out of the boat, personal watercraft use or water skiing, and falling or being thrown from the boat. A case of a scuba diver's death that occurred during an illegal scuba fishing trip around a desalination plant is presented. A complete autopsy and histological study of all organs and surfaces of dismembered cadaveric sections, performed in order to determine the phases of death, are reported. An underwater scene investigation was conducted by an engineering team studying the mouth of the pump and the dynamic characteristic of rotating propeller blades. Copyright © 2015 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.

  10. VizieR Online Data Catalog: SCUBA-2 high-redshift galaxies sample (Barger+, 2014) (United States)

    Barger, A. J.; Cowie, L. L.; Chen, C.-C.; Owen, F. N.; Wang, W.-H.; Casey, C. M.; Lee, N.; Sanders, D. B.; Williams, J. P.


    We obtained 25.4 hr of observations on the CDF-N with SCUBA-2 on the JCMT during observing runs in 2012 and 2013. The data were obtained using a mixture of scanning modes and under a variety of weather conditions. Using the CV Daisy scanning mode (detailed information about the SCUBA-2 scan patterns can be found in Holland et al. 2013MNRAS.430.2513H), we obtained a 2.2 hr observation in band 1 weather (225 GHz opacity<0.05) and a 16.5 hr observation in band 2 weather (225 GHz opacity ~0.05-0.08). We also obtained a 6.7 hr observation in band 2 weather using the pong-900 scanning mode. While SCUBA-2 observes at both 450 um and 850 um simultaneously, there are too few sources directly detected at 450 um in our data to be interesting. Thus, we only use the 850 um data in our subsequent analysis. (1 data file).

  11. Recreational scuba diving in patients with congenital heart disease: Time for new guidelines. (United States)

    Schleich, Jean-Marc; Schnell, Frédéric; Brouant, Benoît; Phan, Gerald; Lafay, Vincent; Bonnemains, Laurent; Bédossa, Marc


    The number of recreational scuba divers is steadily increasing. In its latest recommendations, the French Federation of Undersea Studies and Sports listed congenital heart disease as a formal and final contraindication to scuba diving. On the other hand, with the progress made in their management, the prognosis and quality of life of patients with congenital heart diseases have improved considerably, enabling them to engage in physical and sports endeavours, which are known to confer general health and psychological benefits. As a consequence, the ability of these patients to dive has become a regular and recurrent issue. We review the various types of scuba diving, the physical performance required for its practice, its effects on cardiovascular function and the elements that need to be considered before recommending whether it can be practiced safely at various levels of difficulty. Because of the diversity and broad heterogeneity of congenital heart diseases, a detailed evaluation of each patient's performance based on clinical criteria common to all congenital heart diseases is recommended. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  12. Disposable contact lenses vs. contact lens maintenance for extended wear. (United States)

    Josephson, J E; Caffery, B E; Campbell, I; Slomovic, A R


    We compared a disposable extended wear contact lens modality with conventional extended wear over a 6-week period. To do so, we refit 31 patients who had successfully worn conventional extended wear contact lenses for more than 1 year. One eye was fit with the AcuvueR disposable contact lens, and a new extended wear lens of the type the patient had been wearing was placed on the other eye. At weekly intervals the disposable lens was discarded and a new disposable lens inserted. At the same time, the conventional lens on the fellow eye was cleaned, disinfected, and reinserted. After 6 weeks the ocular response, subjective impressions, and condition of the lenses in the two eyes were compared. Both lenses were then cultured. Three subjects had to discontinue disposable lens wear because of adverse reactions to trapped cellular debris and corneal microcysts. Although the results were not statistically significant, the Acuvue lens appeared to perform better than or equal to the conventional lens in biomicroscopic observation, visual acuity measurement, and subjective patient preference. Eighty-seven percent of patients preferred to continue with the disposable system. There were no differences found in the type or degree of microbial contamination of the lenses.

  13. Pure mechanical wear loss measurement in corrosive wear

    Indian Academy of Sciences (India)


    Abstract. The method for the measurement of the pure mechanical wear loss for 321 stainless steel, 1045 steel and pure iron in the study of the synergy between corrosion and wear was studied. The methods studied included the measurement in distilled water, by cathodic protection and by adding inhibitor KI, and all were.

  14. Wear characteristics in a two-body wear test. (United States)

    Wassell, R W; McCabe, J F; Walls, A W


    A previous report compared spherical steatite (ceramic enamel substitute) abraders with those of natural enamel in a two-body wear test. The wear rates and coefficients of friction of the two abraders against various composites and an amalgam were well correlated although the wear rates were slightly higher with steatite. This report investigates the characteristics of the worn abrader and specimen surfaces. Scanning electron microscopy and laser profilometry were used. Similar wear characteristics were found for the two types of abraders. Adhesive wear was evident for the amalgam, Dispersalloy (Johnson & Johnson), and the heat/pressure-cured microfill composite, Isosit (Ivoclar-Vivadent). Abrasion was seen with the hybrid composite, Occlusin (ICI), and, to a lesser extent, the microfill composite, Heliomolar (Ivoclar-Vivadent). The appearance of the worn small particle hybrid composite, Brilliant Dentin (Coltène), suggested that fatigue and delamination were involved. Laser profilometry showed that the hybrid composites caused much greater wear to the abraders than either the microfill composites or amalgam. The Ra values of the worn abraders and specimens were similar, suggesting conformal contact between them and endorsing the well controlled conditions of the wear test. The results of this and other publications suggest that steatite can be used as an alternative to enamel in performing two-body wear tests on dental composites. This should help significantly in materials evaluation and development.

  15. Pure mechanical wear loss measurement in corrosive wear

    Indian Academy of Sciences (India)

    The method for the measurement of the pure mechanical wear loss for 321 stainless steel, 1045 steel and pure iron in the study of the synergy between corrosion and wear was studied. The methods studied included the measurement in distilled water, by cathodic protection and by adding inhibitor KI, and all were ...

  16. A comparison of spectacle and contact lens wearing times in the ACHIEVE study. (United States)

    Jones-Jordan, Lisa A; Chitkara, Monica; Coffey, Bradley; Jackson, John Mark; Manny, Ruth E; Rah, Marjorie J; Walline, Jeffrey J


    The aim was to compare vision correction wearing time between myopic children and teenagers in a clinical trial of contact lenses and spectacles. Parents of subjects in the Adolescent and Child Health Initiative for Vision Empowerment (ACHIEVE) study provided wearing times for spectacle and contact lens wear. Hours wearing primary correction and total correction were compared between the two treatment groups. Other factors hypothesised to be associated with wearing time were analysed. The average wearing time of the primary correction differed significantly with the wearing time for the spectacles group being 91.5 hours per week compared to 80.3 hours per week for the contact lens wearers (p lenses less than young spectacle wearers and older contact lens wearers. Low scores on an appearance quality-of-life scale were associated with longer wearing time in spectacle wearers compared to the low- and high-scoring contact lens wearers. Gender, spectacle satisfaction and activities were not related to wearing time. While contact lens wearers, on average, wear their contact lenses less than spectacle wearers, they spend roughly the same amount of time wearing a refractive correction. Higher refractive error resulted in longer wearing times for both spectacle and contact lens wearers. Younger contact lens wearers wore their contact lenses for shorter periods than the spectacle wearers, but still wore them, on average, 74.4 hours per week (about 10 hours per day), suggesting that contact lenses are a viable alternative mode of correction for children.

  17. Tyre and road wear prediction

    NARCIS (Netherlands)

    Lupker, H.A.


    Both tyre wear and road polishing are complex phenomenon, which are obviously strongly related; the energy that polishes the road is the energy that wears the tyre. The both depend non-linearly on numerous parameters, like materials used, vehicle and road usage, environmental conditions (i.e.

  18. The influence of laser line hardening of carbon steel AISI 1045 on the lubricated wear against steel AISI 52100

    NARCIS (Netherlands)

    Visscher, H.; de Rooij, Matthias B.; Vroegop, P.H.; Schipper, Dirk J.


    To diminish wear in tribological systems it is not always necessary to provide the entire surface with a wear resistant layer. Depending on the application it is sufficient to harden locally the load carrying areas which are subjected to wear. Such areas can be treated properly by a laser, either

  19. Switch wear leveling (United States)

    Wu, Hunter; Sealy, Kylee; Gilchrist, Aaron


    An apparatus for switch wear leveling includes a switching module that controls switching for two or more pairs of switches in a switching power converter. The switching module controls switches based on a duty cycle control technique and closes and opens each switch in a switching sequence. The pairs of switches connect to a positive and negative terminal of a DC voltage source. For a first switching sequence a first switch of a pair of switches has a higher switching power loss than a second switch of the pair of switches. The apparatus includes a switch rotation module that changes the switching sequence of the two or more pairs of switches from the first switching sequence to a second switching sequence. The second switch of a pair of switches has a higher switching power loss than the first switch of the pair of switches during the second switching sequence.

  20. Prediction of Polyethylene Wear Rates from Gait Biomechanics and Implant Positioning in Total Hip Replacement. (United States)

    Ardestani, Marzieh M; Amenábar Edwards, Pedro P; Wimmer, Markus A


    Patient-specific gait and surgical variables are known to play an important role in wear of total hip replacements (THR). However a rigorous model, capable of predicting wear rate based on a comprehensive set of subject-specific gait and component-positioning variables, has to our knowledge, not been reported. (1) Are there any differences between patients with high, moderate, and low wear rate in terms of gait and/or positioning variables? (2) Can we design a model to predict the wear rate based on gait and positioning variables? (3) Which group of wear factors (gait or positioning) contributes more to the wear rate? Data on patients undergoing primary unilateral THR who performed a postoperative gait test were screened for inclusion. We included patients with a 28-mm metal head and a hip cup made of noncrosslinked polyethylene (GUR 415 and 1050) from a single manufacturer (Zimmer, Inc). To calculate wear rates from radiographs, inclusion called for patients with a series of standing radiographs taken more than 1 year after surgery. Further, exclusion criteria were established to obtain reasonably reliable and homogeneous wear readings. Seventy-three (83% of included) patients met all criteria, and the final dataset consisted of 43 males and 30 females, 69 ± 10 years old, with a BMI of 27.3 ± 4.7 kg/m(2). Wear rates of these patients were determined based on the relative displacement of the femoral head with regard to the cup using a validated computer-assisted X-ray wear-analysis suite. Three groups with low ( 0.2 mm/year) wear were established. Wear prediction followed a two-step process: (1) linear discriminant analysis to estimate the level of wear (low, moderate, or high), and (2) multiple linear and nonlinear regression modeling to predict the exact wear rate from gait and implant-positioning variables for each level of wear. There were no group differences for positioning and gait suggesting that wear differences are caused by a combination of wear

  1. The JCMT and Herschel Gould Belt Surveys: a comparison of SCUBA-2 and Herschel data of dense cores in the Taurus dark cloud L1495 (United States)

    Ward-Thompson, D.; Pattle, K.; Kirk, J. M.; Marsh, K.; Buckle, J.; Hatchell, J.; Nutter, D. J.; Griffin, M. J.; Di Francesco, J.; André, P.; Beaulieu, S.; Berry, D.; Broekhoven-Fiene, H.; Currie, M.; Fich, M.; Jenness, T.; Johnstone, D.; Kirk, H.; Mottram, J.; Pineda, J.; Quinn, C.; Sadavoy, S.; Salji, C.; Tisi, S.; Walker-Smith, S.; White, G.; Hill, T.; Könyves, V.; Palmeirim, P.; Pezzuto, S.


    We present a comparison of Submillimetre Common User Bolometer Array-2 (SCUBA-2) 850-μm and Herschel 70-500-μm observations of the L1495 filament in the Taurus Molecular Cloud with the goal of characterizing the SCUBA-2 Gould Belt Survey (GBS) data set. We identify and characterize starless cores in three data sets: SCUBA-2 850-μm, Herschel 250-μm, and Herschel 250-μm spatially filtered to mimic the SCUBA-2 data. SCUBA-2 detects only the highest-surface-brightness sources, principally detecting protostellar sources and starless cores embedded in filaments, while Herschel is sensitive to most of the cloud structure, including extended low-surface-brightness emission. Herschel detects considerably more sources than SCUBA-2 even after spatial filtering. We investigate which properties of a starless core detected by Herschel determine its detectability by SCUBA-2, and find that they are the core's temperature and column density (for given dust properties). For similar-temperature cores, such as those seen in L1495, the surface brightnesses of the cores are determined by their column densities, with the highest-column-density cores being detected by SCUBA-2. For roughly spherical geometries, column density corresponds to volume density, and so SCUBA-2 selects the densest cores from a population at a given temperature. This selection effect, which we quantify as a function of distance, makes SCUBA-2 ideal for identifying those cores in Herschel catalogues that are closest to forming stars. Our results can now be used by anyone wishing to use the SCUBA-2 GBS data set.

  2. Prolonging contact lens wear and making contact lens wear safer. (United States)

    Foulks, Gary N


    To summarize the present status of safety and efficacy of contact lens wear. Literature review. Ovid Medline searches were performed on records from 1966 through 2005 using keywords: keratitis, contact lens complications, extended-wear contact lenses, and silicone-hydrogel contact lenses. Patients desire comfort, clarity of vision, and prolonged contact lens wear when contact lenses are used to correct refractive error. Practitioners desire patient satisfaction but also require maintenance of the integrity of the eye and no complications that jeopardize vision or health of the eye. Improvements in the oxygen permeability of the contact lens materials, design of the contact lens and its surface, and solutions for the maintenance of the lens have reduced but not eliminated the risks of infection, inflammation, and conjunctival papillary reaction associated with contact lens wear. The lessons of past and recent history suggest that patient education and practitioner participation in the management of contact lens wear continue to be critical factors for patient satisfaction and safety in the extended wear of contact lenses. The availability of highly oxygen permeable contact lenses has increased the tolerance and safety of extended contact lens wear, but patient instruction and education in proper use and care of lenses is required and caution is advised.

  3. Are recreational SCUBA divers with asthma at increased risk?

    DEFF Research Database (Denmark)

    Ustrup, Amalie; Ulrik, Charlotte Suppli


    disease-related hazards in SUBA-divers with asthma. METHODS: Systematic literature review based on the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. RESULTS: Seven studies met the criteria for inclusion in the present review (comprising a total of 560 subjects...

  4. Low friction wear resistant graphene films (United States)

    Sumant, Anirudha V.; Berman, Diana; Erdemir, Ali


    A low friction wear surface with a coefficient of friction in the superlubric regime including graphene and nanoparticles on the wear surface is provided, and methods of producing the low friction wear surface are also provided. A long lifetime wear resistant surface including graphene exposed to hydrogen is provided, including methods of increasing the lifetime of graphene containing wear surfaces by providing hydrogen to the wear surface.

  5. Demographic Factors Affect Ocular Comfort Ratings During Contact Lens Wear. (United States)

    Naduvilath, Thomas; Papas, Eric B; Lazon de la Jara, Percy


    To determine if rating of ocular comfort during soft contact lens wear is affected by demographic factors. Retrospective analysis of ocular comfort ratings during soft contact lens wear extracted from 44 nonrandomized similar clinical trials (n = 986). Subjects wore one of seven daily wear silicone hydrogels (SiHy) in combination with one of nine lens care products (LCP), and two daily disposables lenses. The effects on comfort rating of demographic factors were examined after adjusting for lens and LCP effects using general linear model. Males reported lower comfort on insertion than females (7.9 ± 1.6 vs. 8.1 ± 1.6, p = 0.001). Over 45 years old had higher comfort ratings than those between 26 and 45 or gender, lens wear experience, ethnicity, and refractive status can influence the rating of ocular comfort in clinical studies. The confounding effects of such demographic factors can be controlled by implementing randomization and appropriate multivariable statistical analysis.

  6. Analysis of polymerization time on abrasive wear of dental resins

    Directory of Open Access Journals (Sweden)

    Eduardo Carlos Bianchi


    Full Text Available An evaluation was made of the abrasive wear of six composite thermofixed dental resins subjected to different polymerization times. The method of evaluation was based on sharpness measurements to quantify the abrasive wear resistance of the resins. To this end, a test bench was built, consisting of a rotating porcelain cylinder that wears out a resin-coated cylinder placed above it, thus causing vertical displacement of the contact as the wear progresses. The values of vertical displacement, i.e., the input variables, were read and recorded by means of a computer program to obtain the sharpness values. These data indicated that the resins displayed different behaviors as a function of the polymerization times applied, reinforcing the importance of using a practical and rapid method of analysis in order to ensure that the behavior of new materials is fully understood before they are launched on the market.

  7. The effect of pre-dive ingestion of dark chocolate on endothelial function after a scuba dive. (United States)

    Theunissen, Sigrid; Balestra, Costantino; Boutros, Antoine; De Bels, David; Guerrero, François; Germonpré, Peter


    The aim of the study was to observe the effects of dark chocolate on endothelial function after scuba diving. Forty-two male scuba divers were divided into two groups: a control (n=21) and a chocolate group (n=21). They performed a 33-metres deep scuba-air dive for 20 minutes in a diving pool (Nemo 33, Brussels). Water temperature was 33⁰C. The chocolate group ingested 30 g of dark chocolate (86% cocoa) 90 minutes before the dive. Flow-mediated dilatation (FMD), digital photoplethysmography and nitric oxide (NO) and peroxynitrites (ONOO-) levels were measured before and after the scuba dive in both groups. A significant decrease in FMD was observed in the control group after the dive (91±7% (mean±95% confidence interval) of pre-dive values; Pchocolate group (105±5% of pre-dive values; Pchocolate group (154±73% of pre-dive values; P=0.04). A significant reduction in ONOO- was observed in the control group (84±12% of pre-dive values; P=0.003) whereas no variation was shown after the dive with chocolate intake (100±28% of pre-dive values; ns). Ingestion of 30 g of dark chocolate 90 minutes before scuba diving prevented post-dive endothelial dysfunction, as the antioxidants contained in dark chocolate probably scavenge free radicals.

  8. Decapod assemblages in subtidal and intertidal zones—Importance of scuba diving as a survey technique in tropical reefs, Brazil

    Directory of Open Access Journals (Sweden)

    Bruno Welter Giraldes


    Full Text Available Decapods play a crucial role within the reef ecosystem and the development of scuba diving as a survey tool has allowed researchers the opportunity to study the decapod–reef relationship more comprehensively. The present study describes the differences in decapod assemblages in intertidal and subtidal zones at a tropical coastal reef system in the southwestern Atlantic Ocean and reports the importance of scuba diving as a survey technique. A total of 71 decapods were recorded during the research; 42 in the intertidal zone mainly formed by small endobenthic species and 39 in the subtidal zone primarily large species only 10 were found to frequent both sample zones. The study extends the range of Brachycarpusholthuisi Fausto Filho 1966 in Brazil; and also demonstrates how scuba diving can be used to complement traditional methodologies and vice versa. The research shows the advantages of using scuba diving when studying trade endangered decapods, as the methodology allows access to cryptic habitats such as reef caves and underwater cavities which were inaccessible when using traditional techniques. In conclusion scuba diving represents a revolutionary non-destructive survey tool allowing the researcher to directly access a specific decapod assemblage in fragile reef environments and in protected marine areas.

  9. [Lung function testing in children before and after an age-adapted SCUBA dive in a swimming pool]. (United States)

    Wollin, P; Christmann, M; Kroker, A; Zielen, S


    The number of children that SCUBA dive is increasing. Airway narrowing while SCUBA diving can cause dangerous complications like pulmonary barotrauma and arterial gas embolism. Statistics show that children are at an increased risk. Since data are scarce, the goal of this study was to gain new knowledge about acute lung function changes in children while SCUBA diving. 41 children aged 8 - 14 years underwent lung function testing (spirometry and residual volume measurement) before and after a single age-adapted SCUBA dive in a swimming pool. A significant reduction of the dynamic expiratory lung function parameters FEV (1) (p  10 % (12 % - 21 %) was found in 5 children (12.2 %). The majority of the children (87.8 %) did not show any relevant lung function changes. Five children had a considerable reduction of FEV (1). Signs indicate the importance of bronchial hyperreactivity (BHR) as a key factor. Children with asthma or BHR should not SCUBA dive. A detailed medical examination is recommended (including an unspecific bronchial provocation test) before starting to dive. © Georg Thieme Verlag KG Stuttgart · New York.

  10. Clinical measurement of tooth wear: Tooth Wear Indices


    J. López Frías; Castellanos Cosano, Lizett; Martín González, Jenifer; Llamas Carreras, José María; Segura-Egea, Juan J.


    Attrition, erosion, and abrasion result in alterations to the tooth and manifest as tooth wear. Each classification corresponds to a different process with specific clinical features. Classifications made so far have no accurate prevalence data because the indexes do not necessarily measure a specific etiology, or because the study populations can be diverse in age and characteristics. Tooth wears (attrition, erosion and abrasion) is perceived internationally as a growing problem. However, th...

  11. Analysis of Impact of Chosen Parameters on the Wear of Camshft

    Directory of Open Access Journals (Sweden)

    Burdzik R.


    Full Text Available The paper provides an analysis of the reasons for excessive wear of the camshafts system components based on models developed to describe the impact of selected material, technological and operational factors. The subject of the research was wear of camshaft cams studied in accordance with results of operation tests. Based on the said tests, the dependence of wear intensity of cams from their angular position was established. The respective calculation results enabled the function of cam fallibility to be determined.

  12. Does recreational scuba diving have clinically significant effect on routine haematological parameters? (United States)

    Perovic, Antonija; Nikolac, Nora; Braticevic, Marina Njire; Milcic, Ana; Sobocanec, Sandra; Balog, Tihomir; Dabelic, Sanja; Dumic, Jerka


    Scuba diving represents a combination of exercise and changes in environmental conditions. This study aimed to evaluate changes in haematological parameters after recreational scuba diving in order to identify clinically significant changes. The study included males, 17 recreational divers, median age (range) 41 (30-52) years. Blood samples were taken before diving, immediately after diving to 30 meters for 30 minutes, 3 hours and 6 hours after diving. Complete blood counts were analyzed on the Cell Dyn Ruby haematology analyzer. Statistical significance between successive measurements was tested using Friedman test. The difference between the two measurements was judged against desirable bias (DSB) derived from biological variation and calculated reference change values (RCV). The difference higher than RCV was considered clinically significant. A statistically significant increase and difference judging against DSB was observed: for neutrophils immediately, 3 and 6 hours after diving (18%, 34% and 36%, respectively), for white blood cells (WBCs) 3 and 6 hours after diving (20% and 25%, respectively), for lymphocytes (20%) and monocytes (23%) 6 hours after diving. A statistically significant decrease and difference judging against DSB was found: immediately after diving for monocytes (- 15%), 3 and 6 hours after diving for red blood cells (RBCs) (- 2.6% and -2.9%, respectively), haemoglobin (- 2.1% and - 2.8%, respectively) and haematocrit (- 2.4% and - 3.2%, respectively). A clinically significant change was not found for any of the test parameters when compared to RCV. Observed statistically significant changes after recreational scuba diving; WBCs, neutrophils, lymphocytes, monocytes increase and RBCs, haemoglobin, haematocrit decrease, probably will not affect clinical decision.

  13. Mobility, expansion and management of a multi-species scuba diving fishery in East Africa.

    Directory of Open Access Journals (Sweden)

    Hampus Eriksson

    Full Text Available BACKGROUND: Scuba diving fishing, predominantly targeting sea cucumbers, has been documented to occur in an uncontrolled manner in the Western Indian Ocean and in other tropical regions. Although this type of fishing generally indicates a destructive activity, little attention has been directed towards this category of fishery, a major knowledge gap and barrier to management. METHODOLOGY AND PRINCIPAL FINDINGS: With the aim to capture geographic scales, fishing processes and social aspects the scuba diving fishery that operate out of Zanzibar was studied using interviews, discussions, participant observations and catch monitoring. The diving fishery was resilient to resource declines and had expanded to new species, new depths and new fishing grounds, sometimes operating approximately 250 km away from Zanzibar at depths down to 50 meters, as a result of depleted easy-access stock. The diving operations were embedded in a regional and global trade network, and its actors operated in a roving manner on multiple spatial levels, taking advantage of unfair patron-client relationships and of the insufficient management in Zanzibar. CONCLUSIONS AND SIGNIFICANCE: This study illustrates that roving dynamics in fisheries, which have been predominantly addressed on a global scale, also take place at a considerably smaller spatial scale. Importantly, while proposed management of the sea cucumber fishery is often generic to a simplified fishery situation, this study illustrates a multifaceted fishery with diverse management requirements. The documented spatial scales and processes in the scuba diving fishery emphasize the need for increased regional governance partnerships to implement management that fit the spatial scales and processes of the operation.

  14. Understanding scuba diving fatalities: carbon dioxide concentrations in intra-cardiac gas. (United States)

    Varlet, Vincent; Dominguez, Alejandro; Augsburger, Marc; Lossois, Maisy; Egger, Coraline; Palmiere, Cristian; Vilarino, Raquel; Grabherr, Silke


    Important developments in the diagnosis of scuba diving fatalities have been made thanks to forensic imaging tool improvements. Multi-detector computed tomography (MDCT) permits reliable interpretation of the overall gaseous distribution in the cadaver. However, due to post-mortem delay, the radiological interpretation is often doubtful because the distinction between gas related to the dive and post-mortem decomposition artifactual gases becomes less obvious. We present six cases of fatal scuba diving showing gas in the heart and other vasculature. Carbon dioxide (CO₂) in cardiac gas measured by gas chromatography coupled to thermal conductivity detection were employed to distinguish decomposition from embolism based on the detection of decomposition gases (hydrogen, hydrogen sulfide and methane) and to confirm arterial gas embolism (AGE) or post-mortem offgasing diagnoses. A Radiological Alteration Index (RAI) was calculated from the scan. Based on the dive history, the intra-cadaveric gas was diagnosed as deriving from decomposition (one case, minimal RAI of 61), post-mortem decompression artifacts (two cases, intermediate RAI between 60 and 85) and barotrauma/AGE (three cases, maximal RAI between 85 and 100), illustrating a large distribution inside the bodies. MDCT scans should be interpreted simultaneously with compositional analysis of intra-cadaveric gases. Intra-cadaveric gas sampling and analysis may become useful tools for understanding and diagnosing scuba diving fatalities. In cases with short post-mortem delays, the CO₂ concentration of the cardiac gas provides relevant information about the circumstances and cause of death when this parameter is interpreted in combination with the diving profile.

  15. Assessment of extravascular lung water and cardiac function in trimix SCUBA diving. (United States)

    Marinovic, Jasna; Ljubkovic, Marko; Obad, Ante; Breskovic, Toni; Salamunic, Ilza; Denoble, Petar J; Dujic, Zeljko


    An increasing number of recreational self-contained underwater breathing apparatus (SCUBA) divers use trimix of oxygen, helium, and nitrogen for dives deeper than 60 m of sea water. Although it was seldom linked to the development of pulmonary edema, whether SCUBA diving affects the extravascular lung water (EVLW) accumulation is largely unexplored. Seven divers performed six dives on consecutive days using compressed gas mixture of oxygen, helium, and nitrogen (trimix), with diving depths ranging from 55 to 80 m. The echocardiographic parameters (bubble grade, lung comets, mean pulmonary arterial pressure (PAP), and left ventricular function) and the blood levels of the N-terminal part of pro-brain natriuretic peptide (NT-proBNP) were assessed before and after each dive. Venous gas bubbling was detected after each dive with mean probability of decompression sickness ranging from 1.77% to 3.12%. After each dive, several ultrasonographically detected lung comets rose significantly, which was paralleled by increased pulmonary artery pressure (PAP) and decreased left ventricular contractility (reduced ejection fraction at higher end-systolic and end-diastolic volumes) as well as the elevated NT-proBNP. The number of ultrasound lung comets and mean PAP did not return to baseline values after each dive. This is the first report that asymptomatic SCUBA dives are associated with accumulation of EVLW with concomitant increase in PAP, diminished left ventricular contractility, and increased release of NT-proBNP, suggesting a significant cardiopulmonary strain. EVLW and PAP did not return to baseline during repetitive dives, indicating possible cumulative effect with increasing the risk for pulmonary edema.

  16. The Herschel Bright Sources (HerBS): sample definition and SCUBA-2 observations (United States)

    Bakx, Tom J. L. C.; Eales, S. A.; Negrello, M.; Smith, M. W. L.; Valiante, E.; Holland, W. S.; Baes, M.; Bourne, N.; Clements, D. L.; Dannerbauer, H.; De Zotti, G.; Dunne, L.; Dye, S.; Furlanetto, C.; Ivison, R. J.; Maddox, S.; Marchetti, L.; Michałowski, M. J.; Omont, A.; Oteo, I.; Wardlow, J. L.; van der Werf, P.; Yang, C.


    We present the Herschel Bright Sources (HerBS) sample, a sample of bright, high-redshift Herschel sources detected in the 616.4 deg2 Herschel Astrophysical Terahertz Large Area Survey. The HerBS sample contains 209 galaxies, selected with a 500 μm flux density greater than 80 mJy and an estimated redshift greater than 2. The sample consists of a combination of hyperluminous infrared galaxies and lensed ultraluminous infrared galaxies during the epoch of peak cosmic star formation. In this paper, we present Submillimetre Common-User Bolometer Array 2 (SCUBA-2) observations at 850 μm of 189 galaxies of the HerBS sample, 152 of these sources were detected. We fit a spectral template to the Herschel-Spectral and Photometric Imaging Receiver (SPIRE) and 850 μm SCUBA-2 flux densities of 22 sources with spectroscopically determined redshifts, using a two-component modified blackbody spectrum as a template. We find a cold- and hot-dust temperature of 21.29_{-1.66}^{+1.35} and 45.80_{-3.48}^{+2.88} K, a cold-to-hot dust mass ratio of 26.62_{-6.74}^{+5.61} and a β of 1.83_{-0.28}^{+0.14}. The poor quality of the fit suggests that the sample of galaxies is too diverse to be explained by our simple model. Comparison of our sample to a galaxy evolution model indicates that the fraction of lenses are high. Out of the 152 SCUBA-2 detected galaxies, the model predicts 128.4 ± 2.1 of those galaxies to be lensed (84.5 per cent). The SPIRE 500 μm flux suggests that out of all 209 HerBS sources, we expect 158.1 ± 1.7 lensed sources, giving a total lensing fraction of 76 per cent.

  17. Surface roughness and wear of resin cements after toothbrush abrasion

    Directory of Open Access Journals (Sweden)

    Sérgio Kiyoshi ISHIKIRIAMA


    Full Text Available Increased surface roughness and wear of resin cements may cause failure of indirect restorations. The aim of this study was to evaluate quantitatively the surface roughness change and the vertical wear of four resin cements subjected to mechanical toothbrushing abrasion. Ten rectangular specimens (15 × 5 × 4 mm were fabricated according to manufacturer instructions for each group (n = 10: Nexus 3, Kerr (NX3; RelyX ARC, 3M ESPE (ARC; RelyX U100, 3M ESPE (U100; and Variolink II, Ivoclar/Vivadent (VL2. Initial roughness (Ra, µm was obtained through 5 readings with a roughness meter. Specimens were then subjected to toothbrushing abrasion (100,000 cycles, and further evaluation was conducted for final roughness. Vertical wear (µm was quantified by 3 readings of the real profile between control and brushed surfaces. Data were subjected to analysis of variance, followed by Tukey’s test (p < 0.05. The Pearson correlation test was performed between the surface roughness change and wear (p < 0.05. The mean values of initial/final roughness (Ra, µm/wear (µm were as follows: NX3 (0.078/0.127/23.175; ARC (0.086/0.246/20.263; U100 (0.296/0.589/16.952; and VL2 (0.313/0.512/22.876. Toothbrushing abrasion increased surface roughness and wear of all resin cements tested, although no correlation was found between those variables. Vertical wear was similar among groups; however, it was considered high and may lead to gap formation in indirect restorations.

  18. A SCUBA imaging survey of ultracompact HII regions: The environments of massive star formation


    Thompson, M. A.; Hatchell, J.; Walsh, A. J.; Macdonald, G. H.; Millar, T. J.


    We present a SCUBA submillimetre (450 & 850 micron) survey of the environment of 105 IRAS point sources, selected from the Wood & Churchwell (1989a) and Kurtz, Churchwell & Wood (1994) radio ultracompact (UC) HII region surveys. We detected a total of 155 sub-mm clumps associated with the IRAS point sources and identified three distinct types of object: ultracompact cm-wave sources that are not associated with any sub-mm emission (sub-mm quiet objects), sub-mm clumps that are associated with ...

  19. The JCMT Gould Belt Survey: SCUBA-2 observations of radiative feedback in NGC1333


    Hatchell, J.; Wilson, T; Drabek, E.; Curtis, E; Richer, J; Nutter, D.; Di Francesco, J.; consortium, D. Ward-Thompson on behalf of the JCMT GBS


    We present observations of NGC1333 from SCUBA-2 on JCMT, observed as a JCMT Gould Belt Survey pilot project during the shared risk campaign when the first of four arrays was installed at each of 450 and 850 microns. Temperature maps are derived from 450 micron and 850 micron ratios under the assumption of constant dust opacity spectral index beta=1.8. Temperatures indicate that the dust in the northern (IRAS 6/8) region of NGC1333 is hot, 20-40 K, due to heating by the B star SVS3, other youn...

  20. Evaluation of hardness and wear resistance of interim restorative materials. (United States)

    Savabi, Omid; Nejatidanesh, Farahnaz; Fathi, Mohamad Hossein; Navabi, Amir Arsalan; Savabi, Ghazal


    The interim restorative materials should have certain mechanical properties to withstand in oral cavity. The aim of this study was to evaluate the hardness and wear resistance of interim restorative materials. Fifteen identical rectangular shape specimens with dimensions of 2 mm × 10 mm × 30 mm were made from 7 interim materials (TempSpan, Protemp 3 Garant, Revotek, Unifast LC, Tempron, Duralay, and Acropars). The Vickers hardness and abrasive wear of specimens were tested in dry conditions and after 1 week storage in artificial saliva. The depth of wear was measured using surface roughness inspection device. Data were subjected to Kruskal-Wallis and Mann-Whitney tests. The Pearson correlation coefficient was used to determine the relationship between hardness and wear (α =0.05). TempSpan had the highest hardness. The wear resistance of TempSpan (in dry condition) and Revotek (after conditioning in artificial saliva) was significantly higher (P materials (P = 0.281, r = -0.31). Hardness and wear resistance of interim resins are material related rather than category specified.

  1. Wear behaviour of Al 261

    Directory of Open Access Journals (Sweden)

    N. Mathan Kumar


    Full Text Available Al 2618 matrix material was mixed with the Silicon Nitride (Si3N4, Aluminium Nitride (AlN and Zirconium Boride (ZrB2 reinforced particles. AMC was synthesized successfully by the stir casting method with the various X-wt.% of reinforcements (X = 0,2,4,6,8. Tribological behaviour was studied in this composite with various temperature conditions. The working conditions were Temperature (°C, Load (N, Velocity (m/s and Sliding Distances (m. Before wear testing the mechanical behaviour has been analysed. EDAX was confirmed by the matrix material composition. The Al 2618 alloy and the reinforcement mixers were confirmed by the X-ray Diffraction analysis. Wear rate (mm3/m, Wear resistance (m/mm3, Specific Wear rate (m/Nm and Co-efficient of friction (μ were analysed with various conditions. The worn surfaces were analysed before and after wear testing by Scanning Electron Microscope (SEM. Influence of process parameters and Percentage of contribution were analysed by Taguchi and Analysis of Variance (ANOVA methods. Genetic Algorithm (GA was adopted for optimizing the best and mean of the wear rate and to identify the exact influence of input parameters.

  2. Tool Wear in Friction Drilling

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Scott F [ORNL; Blau, Peter Julian [ORNL; Shih, Albert J. [University of Michigan


    This study investigated the wear of carbide tools used in friction drilling, a nontraditional hole-making process. In friction drilling, a rotating conical tool uses the heat generated by friction to soften and penetrate a thin workpiece and create a bushing without generating chips. The wear of a hard tungsten carbide tool used for friction drilling a low carbon steel workpiece has been investigated. Tool wear characteristics were studied by measuring its weight change, detecting changes in its shape with a coordinate measuring machine, and making observations of wear damage using scanning electron microscopy. Energy dispersive spectroscopy was applied to analyze the change in chemical composition of the tool surface due to drilling. In addition, the thrust force and torque during drilling and the hole size were measured periodically to monitor the effects of tool wear. Results indicate that the carbide tool is durable, showing minimal tool wear after drilling 11000 holes, but observations also indicate progressively severe abrasive grooving on the tool tip.

  3. Gear Tooth Wear Detection Algorithm (United States)

    Delgado, Irebert R.


    Vibration-based condition indicators continue to be developed for Health Usage Monitoring of rotorcraft gearboxes. Testing performed at NASA Glenn Research Center have shown correlations between specific condition indicators and specific types of gear wear. To speed up the detection and analysis of gear teeth, an image detection program based on the Viola-Jones algorithm was trained to automatically detect spiral bevel gear wear pitting. The detector was tested using a training set of gear wear pictures and a blind set of gear wear pictures. The detector accuracy for the training set was 75 percent while the accuracy for the blind set was 15 percent. Further improvements on the accuracy of the detector are required but preliminary results have shown its ability to automatically detect gear tooth wear. The trained detector would be used to quickly evaluate a set of gear or pinion pictures for pits, spalls, or abrasive wear. The results could then be used to correlate with vibration or oil debris data. In general, the program could be retrained to detect features of interest from pictures of a component taken over a period of time.

  4. Critical component wear in heavy duty engines

    CERN Document Server

    Lakshminarayanan, P A


    The critical parts of a heavy duty engine are theoretically designed for infinite life without mechanical fatigue failure. Yet the life of an engine is in reality determined by wear of the critical parts. Even if an engine is designed and built to have normal wear life, abnormal wear takes place either due to special working conditions or increased loading.  Understanding abnormal and normal wear enables the engineer to control the external conditions leading to premature wear, or to design the critical parts that have longer wear life and hence lower costs. The literature on wear phenomenon r


    Nagakura, Toshikazu; Tanaka, Katsuichirou; Horikawa, Satoshi


    We here report a 34-years old male who had nattou-(fermented-soybean) induced late-onset anaphylaxis following SCUBA diving to about 20 m in the ocean off a small remote Japanese island (Kuroshima, Okinawa). He had eaten nattou for breakfast at 7:30 am. He traveled by boat to the dive site, dove twice and then ate lunch at 12:30 on the diving boat (no nattou at lunch). After lunch at 14:30 he dove again (third dive of the day) during which time itchiness started. Back on the diving boat, urticarial was noticed. At 15:30, while washing his diving gear at the diving shop near the harbor, he fainted. A physician arrived on the scene at 15:45. Chest sound was clear and SpO2 was 98%, and blood pressure was 60/- mmHg. Intra-venous hydrocortisone was given, however, his recovery was not satisfactory. Then he was transferred to the Yaeyama Hospital by helicopter at 17:45. The examination of diving computer analysis reveals no sign of increased residual nitrogen, denying the possibility of decompression syndrome. Prick to prick test shows a strongly positive response to nattou. Nattou-induced late-onset anaphylaxis following SCUBA diving was suspected.

  6. Funding conservation through use and potentials for price discrimination among scuba divers at Sipadan, Malaysia. (United States)

    Emang, Diana; Lundhede, Thomas Hedemark; Thorsen, Bo Jellesmark


    The protected coral reefs off the coast of Malaysia receive numerous tourists, while also being as fishing grounds. These joint environmental pressures raise the need for additional costly conservation measures. It is natural to consider the potential for expanding the 'user pays' principle, already implemented in the form of various user fees. This study explores the potential for price discrimination among scuba divers at Sipadan in Malaysia. The study applies a choice experiment to estimate scuba divers willingness to pay higher user fees for avoiding decreases of or getting improvements in environmental and recreational aspects of the diving experience. We investigate how sensitivity to fee size and hence willingness to pay vary with suitable selected characteristics of divers. We find potentials for a third degree price discrimination strategy exploiting higher willingness to pay among foreign divers (45%), male divers (16%) and people who has visited Sipadan several times (25%). Thus, revised pricing structures could significantly increase funds for the preservation of Sipadan. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Diving dentistry: a review of the dental implications of scuba diving. (United States)

    Zadik, Y; Drucker, S


    In light of the overwhelming popularity of self-contained underwater breathing apparatus (SCUBA) diving, general dental practitioners should be prepared to address complications arising as a result of diving and to provide patients with accurate information. The aim of this article was to introduce the concepts of diving medicine and dentistry to the dentist, and to supply the dental practitioner with some diagnostic tools as well as treatment guidelines. The literature was reviewed to address diving barotrauma (pressure-induced injury related to an air space) to the head, face and oral regions, as well as scuba mouthpiece-related oral conditions. The relevant conditions for dentists who treat divers include diving-associated headache (migraine, tension-type headache), barosinusitis and barotitis-media (sinus and middle ear barotrauma, respectively), neuropathy, trigeminal (CN V) or facial (CN VII) nerve baroparesis (pressure-induced palsy), dental barotrauma (barometric-related tooth injury), barodontalgia (barometric-related dental pain), mouthpiece-associated herpes infection, pharyngeal gag reflex and temporomandibular joint disorder (dysfunction). For each condition, a theoretical description is followed by practical recommendations for the dental practitioner for the prevention and management of the condition. © 2011 Australian Dental Association.

  8. The SCUBA-2 Cosmology Legacy Survey: demographics of the 450-μm population (United States)

    Roseboom, I. G.; Dunlop, J. S.; Cirasuolo, M.; Geach, J. E.; Smail, I.; Halpern, M.; van der Werf, P.; Almaini, O.; Arumugam, V.; Asboth, V.; Auld, R.; Blain, A.; Bremer, M. N.; Bock, J.; Bowler, R. A. A.; Buitrago, F.; Chapin, E.; Chapman, S.; Chrysostomou, A.; Clarke, C.; Conley, A.; Coppin, K. E. K.; Danielson, A. L. R.; Farrah, D.; Glenn, J.; Hatziminaoglou, E.; Ibar, E.; Ivison, R. J.; Jenness, T.; van Kampen, E.; Karim, A.; Mackenzie, T.; Marsden, G.; Meijerink, R.; Michałowski, M. J.; Oliver, S. J.; Page, M. J.; Pearson, E.; Scott, Douglas; Simpson, J. M.; Smith, D. J. B.; Spaans, M.; Swinbank, A. M.; Symeonidis, M.; Targett, T.; Valiante, E.; Viero, M.; Wang, L.; Willott, C. J.; Zemcov, M.


    We investigate the multiwavelength properties of a sample of 450-μm-selected sources from the SCUBA-2 Cosmology Legacy Survey. A total of 69 sources were identified above 4σ in deep SCUBA-2 450-μm observations overlapping the UDS and COSMOS fields and covering 210 arcmin2 to a typical depth of σ450 = 1.5 mJy. Reliable cross-identifications are found for 58 sources (84 per cent) in Spitzer and Hubble Space Telescope WFC3/IR data. The photometric redshift distribution (dN/dz) of 450-μm-selected sources is presented, showing a broad peak in the redshift range 1 = 1012 ± 0.8 L⊙, = 42 ± 11 K and = 1.6 ± 0.5, respectively. The relationship between these SED parameters and the physical properties of galaxies is investigated, revealing correlations between TD and LIR and between βD and both stellar mass and effective radius. The connection between the star formation rate (SFR) and stellar mass is explored, with 24 per cent of 450-μm sources found to be `starbursts', i.e. displaying anomalously high specific SFRs. However, both the number density and observed properties of these `starburst' galaxies are found to be consistent with the population of normal star-forming galaxies.

  9. JCMT Telescope structure modifications and facility upgrades for SCUBA-2 instrument (United States)

    Chylek, Tomas; Craig, Simon C.; Chuter, Timothy C.; Lewsley, Harry J.; Hileman, Edward A.


    The James Clerk Maxwell Telescope (JCMT) on the summit of Mauna Kea is currently undergoing significant structural upgrade in order to accommodate the new generation instrument SCUBA-2 (Submillimeter Common-User Bolometric Array) which is being developed by the United Kingdom Astronomy Technology Centre (UK ATC). This four tonne instrument will be located at the Nasmyth focus of the telescope and will require five large auxiliary external warm mirrors to be installed on the telescope structure and in the receiver cabin along with dedicated automatically deployable tertiary mirror. The carousel of the observatory building as well as the original telescope structure was not designed for an instrument of this mass and complexity. The whole left Nasmyth platform of the telescope has to be removed and rebuilt in order to accommodate the instrument, its support structure and the warm optics. The floor of the observatory has to be reinforced and fitted with rail system and a scissor lift in order to handle the installation of the instrument on the telescope and removal from the telescope for maintenance. Details are given of particular challenges associated with handling, mechanical interfacing, optical alignment, design of the external warm mirrors mounts and the tertiary mirror deployment mechanism for SCUBA-2.

  10. Abrasive wear behavior of heat-treated ABC-silicon carbide

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiao Feng; Lee, Gun Y.; Chen, Da; Ritchie, Robert O.; De Jonghe, Lutgard C.


    Hot-pressed silicon carbide, containing aluminum, boron, and carbon additives (ABC-SiC), was subjected to three-body and two-body wear testing using diamond abrasives over a range of sizes. In general, the wear resistance of ABC-SiC, with suitable heat treatment, was superior to that of commercial SiC.

  11. Tear film inflammatory mediators during continuous wear of contact lenses and corneal refractive therapy


    González-Pérez, Javier; Villa-Collar, César; Sobrino Moreiras, Tomás; Lema Gesto, Isabel; González-Méijome, José Manuel; Rodríguez Ares, María T.; Parafita, Manuel A.


    OBJECTIVES: To study changes in tear film inflammatory mediators following continuous wear of silicone-hydrogel lenses and corneal refractive therapy with reverse geometry contact lenses. DESIGN: A prospective, case-control study. METHODS: Twenty-eight subjects had worn silicone-hydrogel lenses on a 30-night continuous wear basis. Thirty-two subjects had worn corneal refractive therapy lenses on an overnight basis. Thirty-two matched control subjects were also recruited. Tear samples ...

  12. Objective measurement of spectacle wear with a temperature sensor data logger. (United States)

    Lentsch, Matthew J; Marsack, Jason D; Anderson, Heather A


    This study seeks to establish the utility of the SmartButton Data Logger ( to monitor spectacle wear for research and clinical applications. Fifty adults wore a thermosensor on their spectacles for 2 weeks for each of two mount types while keeping wear-time logs. Temperatures during reported spectacle wear (ON) were compared to temperatures during non-wear (OFF) with repeated measures analysis of variance (ANOVA). In addition, two strategies to approximate spectacle wear from temperature data were evaluated: (1) Filtering data based on temperature ranges to identify spectacle wear (either group mean ON temperature, or an individual's mean ON temperature), and (2) Separate examiners inspecting temperature against time plots to identify spectacle wear. The success of these methods to approximate wear time was evaluated by per cent error with respect to subject reported wear time. Group mean ON (31.8 [0.6]°Celsius [°C]) and OFF (24.7 [1.5]°C) temperatures differed significantly (F1,47  = 471.2, p spectacle compliance in patients with all approximation methods evaluated providing less than 10% median per cent error in wear time. © 2017 The Authors Ophthalmic & Physiological Optics © 2017 The College of Optometrists.

  13. The SCUBA-2 Cosmology Legacy Survey: ALMA Resolves the Bright-end of the Sub-millimeter Number Counts

    NARCIS (Netherlands)

    Simpson, J. M.; Smail, Ian; Swinbank, A. M.; Chapman, S. C.; Geach, J. E.; Ivison, R. J.; Thomson, A. P.; Aretxaga, I.; Blain, A. W.; Cowley, W. I.; Chen, Chian-Chou; Coppin, K. E. K.; Dunlop, J. S.; Edge, A. C.; Farrah, D.; Ibar, E.; Karim, A.; Knudsen, K. K.; Meijerink, R.; Michałowski, M. J.; Scott, D.; Spaans, M.; van der Werf, P. P.

    We present high-resolution 870 μm Atacama Large Millimeter/sub-millimeter Array (ALMA) continuum maps of 30 bright sub-millimeter sources in the UKIDSS UDS field. These sources are selected from deep, 1 degree2 850 μm maps from the SCUBA-2 Cosmology Legacy Survey, and are representative of the

  14. The SCUBA-2 Cosmology Legacy Survey: Multi-wavelength Properties of ALMA-identified Submillimeter Galaxies in UKIDSS UDS

    NARCIS (Netherlands)

    Simpson, J. M.; Smail, Ian; Swinbank, A. M.; Ivison, R. J.; Dunlop, J. S.; Geach, J. E.; Almaini, O.; Arumugam, V.; Bremer, M. N.; Chen, Chian-Chou; Conselice, C.; Coppin, K. E. K.; Farrah, D.; Ibar, E.; Hartley, W. G.; Ma, C. J.; Michałowski, M. J.; Scott, D.; Spaans, M.; Thomson, A. P.; van der Werf, P. P.


    We present a multi-wavelength analysis of 52 submillimeter galaxies (SMGs), identified using ALMA 870 μm continuum imaging in a pilot program to precisely locate bright SCUBA-2-selected submillimeter sources in the UKIDSS Ultra Deep Survey (UDS) field. Using the available deep (especially

  15. Scuba diving & underwater cultural resources: differences in environmental beliefs, ascriptions of responsibility, and management preferences based on level of development (United States)

    Sharon L. Todd; Tiffany Cooper; Alan R. Graefe


    This study examined SCUBA divers' level of development in relationship to environmental beliefs, ascriptions of responsibility, and management preferences concerning the use and management of New York's Great Lakes' underwater cultural resources. More than 850 New York State divers were surveyed during the fall of 1999, ranging from novices to experts...

  16. Sensation Seeking: A Potential Factor Influencing Perceived Risk and Perceived Competence in an Introductory Scuba Diving Course (United States)

    Morgan, Cass


    This study examined the relationship between the sensation-seeking personality trait to changes in perceived risk and perceived competence during an adventure experience. Participants (n = 57) were enrolled in a 14-week introductory scuba diving course offered at a university in eastern North Carolina in 2006. The data was analyzed using a…

  17. The Hawaii SCUBA-2 Lensing Cluster Survey: Are Low-luminosity Submillimeter Galaxies Detected in the Rest-frame UV? (United States)

    Hsu, Li-Yen; Cowie, Lennox L.; Barger, Amy J.; Wang, Wei-Hao


    In this third paper of the Hawaii SCUBA-2 Lensing Cluster Survey series, we present Submillimeter Array (SMA) detections of six intrinsically faint 850 μm sources detected in SCUBA-2 images of the lensing cluster fields, A1689, A2390, A370, MACS J0717.5+3745, and MACS J1423.8+2404. Two of the SCUBA-2 sources split into doublets, yielding a total of eight SMA detections. The intrinsic 870 μm flux densities of these submillimeter galaxies (SMGs) are ∼1 mJy. Five of the eight SMGs are not detected in optical or near-infrared (NIR) images. The NIR-to-submillimeter flux ratios of these faint SMGs suggest that most of them are extremely dusty and/or are at very high redshifts. By combining these SMGs and several other samples from the literature, we find a bimodal distribution for the faint sources in the space of submillimeter flux versus NIR-to-submillimeter flux ratio. While most of the SMA-detected lensed sources are very obscured, the other SMGs with similar flux densities are mostly bright in the NIR. Future Atacama Large Millimeter/submillimeter Array observations of a large sample of SCUBA-2 sources in cluster fields will allow us to decide whether or not the bimodality we observe here really exists.

  18. EOWD-Eco Open Water Diver- New Divers License needed? Effect of Intensive SCUBA Diving on Fringing Reefs of the Northern Red Sea

    DEFF Research Database (Denmark)

    Hasler-Sheetal, Harald


    Intensive recreational SCUBA diving threatens coral reef diversity and health [1]. Two anthropogenic factors contributing to coral reef decline are sedimentation [4] and damage from snorklers and SCUBA divers [1]. Physical contact of divers (fins, hands, equipment) and increased sedimentation...... are two major effects diredtly caused by SCUBA diving. Diver damage varies depending on the growth form of corals present. Branching corals appear to sustain most of the breaks although they are most affected [5]. As coral reef tourism continues to grow, the need to quantify, manage and mitigate...

  19. Rigid gas-permeable vs. hydrogel contact lenses for extended wear. (United States)

    Fonn, D; Holden, B A


    A clinical trial was conducted to compare the extended wear performance of rigid gas-permeable (RGP) contact lenses with that of soft lenses. Subjects were fitted with a RGP lens (Boston IV) in one eye and a soft lens (Bausch & Lomb "O" series) in the other eye, and wore them on an extended wear basis for up to 3 months. No subjects developed any acute adverse reactions in the RGP lens-wearing eye. After the initial adaptation period, subject acceptance of RGP extended wear in terms of vision and comfort was superior. The RGP lenses also induced less chronic hypoxic stress than hydrogel lenses of comparable Dk/L, as evidenced by the presence of epithelial microcysts. Several complications of RGP extended wear were observed including lens binding, blepharoptosis, transient pupil size increases, and corneal staining. As hypoxia-induced corneal changes, such as microcysts and striae, were observed in the RGP lens-wearing eyes, we consider that these particular RGP lenses do not have adequate oxygen transmissibility for successful long-term extended wear. However, if RGP lens materials of higher oxygen transmissibility and better designs can be attained, the potential of RGP extended wear would appear promising.

  20. Engineering wear-resistant surfaces in automotive aluminum (United States)

    Kavorkijan, V.


    Inadequate wear resistance and low seizure loads prevent the direct use of aluminum alloys in automotive parts subject to intensive friction combined with high thermal and mechanical loading, such as brake discs, pistons, and cylinder liners. To enable the use of aluminum alloys in the production of automotive brake discs and other wear-resistant products, the insertion of a monolithic friction cladding rather than surface coating has been considered in this work. Three experimental approaches, two based on the pressure-less infiltration of porous ceramic preforms and one based on the subsequent hot rolling of aluminum and metal-matrix composite strips, are currently under investigation.

  1. Lens adherence and postlens tear film changes in closed-eye wear of hydrogel lenses. (United States)

    Bruce, A S; Mainstone, J C


    Lens adherence and a reduced postlens tear film circulation have been suggested as factors contributing to some adverse reactions in extended wear of hydrogel contact lenses. In this study, we determined lens fitting and postlens tear film characteristics during closed-eye wear. Twenty subjects wore hydrogel lenses for 3 h of eye closure, followed by 30 min of open-eye wear. Lens movement was measured with a video biomicroscope. Postlens tear film appearances in specular reflection were classified as either amorphous, or as one of four color intensity grades, where a colored appearance was taken as indicative of a depleted postlens tear film. All subjects showed lens adherence (movement colored postlens tear film patterns of any intensity. Closed-eye wear was invariably associated with the onset of lens adherence and postlens tear film depletion. This finding emphasizes the need for adequate lens movement during the open-eye phase of extended wear.

  2. Lumbar spine orthosis wearing. I. Restriction of gross body motions. (United States)

    Lantz, S A; Schultz, A B


    The effects of wearing commonly prescribed low-back braces and corsets on restriction of gross body motions were investigated. A lumbosacral corset, a chairback brace, and a molded plastic thoracolumbosacral orthosis (TLSO) were studied. Four trunk movements (flexion, extension, lateral bending, and twisting) were examined in five healthy adult men when standing and sitting. All three orthoses restricted at least some gross body motion to approximately two thirds to one half of no-orthosis values. All three orthoses failed to provide restrictions of at least 10% in at least one motion. Mean motion restriction across all eight movements studied in all five subjects were largest when wearing the TLSO and least when wearing the corset. Gross body motion restrictions relieve lumbar trunk muscle and spine loads.

  3. Scuba diving, acute left anterior descending artery occlusion and normal ECG (United States)

    Doll, Sébastien Xavier; Rigamonti, Fabio; Roffi, Marco; Noble, Stéphane


    We report the case of an acute proximal occlusion of the left anterior descending coronary (LAD) artery following a scuba diving decompression accident and associated with normal ECG. Following uneventful thromboaspiration and coronary stenting, the patient was discharged on day  4 with secondary preventative therapies. A transthoracic echocardiography performed at this point showed a complete recovery compared with an initial localised akinesia involving the anterior and apical portion of the left ventricle upon admission. This case highlights that significant acute coronary lesions involving the LAD can occur without any ECG anomaly. The presence of acute and persistent angina associated with troponin elevation should prompt physicians to consider coronary angiography without delay, independently of the ECG results. PMID:23376677

  4. A Review of SCUBA Diving Impacts and Implication for Coral Reefs Conservation and Tourism Management

    Directory of Open Access Journals (Sweden)

    Zainal Abidin Siti Zulaiha


    Full Text Available Dive tourism has become important in term of magnitude and significantly contributes to regional economies. Nevertheless, in the absence of proper controls and enforcement, unplanned tourism growth has caused environmental degradation which undermines the long-term sustainability of the tourism industry. The purpose of this paper is to explore factors that contribute to the SCUBA diving impacts on coral and fish communities. This paper explains the causes of a certain event, validating the problem of impacts, defining the core issues and identifies possible causes leading to an effect. The phenomenon of diving impacts on coral reefs is a result of intensive use of dive site over the long-term. The divers can reduce their impacts towards coral reefs through responsible diving behaviors. The causes of cumulative diver’s contacts are more complicated than it seems. In response, this paper proposes the best mitigation strategies that need to be considered for future dive tourism management.

  5. SCUBA divers as oceanographic samplers: The potential of dive computers to augment aquatic temperature monitoring (United States)

    Wright, Serena; Hull, Tom; Sivyer, David B.; Pearce, David; Pinnegar, John K.; Sayer, Martin D. J.; Mogg, Andrew O. M.; Azzopardi, Elaine; Gontarek, Steve; Hyder, Kieran


    Monitoring temperature of aquatic waters is of great importance, with modelled, satellite and in-situ data providing invaluable insights into long-term environmental change. However, there is often a lack of depth-resolved temperature measurements. Recreational dive computers routinely record temperature and depth, so could provide an alternate and highly novel source of oceanographic information to fill this data gap. In this study, a citizen science approach was used to obtain over 7,000 scuba diver temperature profiles. The accuracy, offset and lag of temperature records was assessed by comparing dive computers with scientific conductivity-temperature-depth instruments and existing surface temperature data. Our results show that, with processing, dive computers can provide a useful and novel tool with which to augment existing monitoring systems all over the globe, but especially in under-sampled or highly changeable coastal environments. PMID:27445104

  6. Creativity in the Research Process. Accompanying Aristotle on a scuba diving excursion in the Red Sea

    Directory of Open Access Journals (Sweden)

    Åke Nilsén


    Full Text Available The paper investigates creativity as an attitude on demand from the researcher in a special situation in the research process. The situation occurs when the collected data does not coinside with the antecipated result. Hans Joas understanding of creative action is abolished for the adaptation of the Aristotelian concept of practical wisdom (phronesis as the foundation for the attitude. The data has to be analysed with the unique and particular in focus in order for new connections and relations to be revealed. An attitude concentrated on revealing the particular in the data is necessary. From there a new attitude takes over that focuses the general on behalf of the particular. The research process is exposed in a parallell text on Scuba diving.

  7. Automotive brake wear: a review. (United States)

    Wahid, Syed M S


    Road transport systems generate toxic particulate matter (PM) when in motion, that ultimately finds its way to the atmosphere. The PM produced by road transport systems can be broadly classified as exhaust and non-exhaust emissions. Exhaust emission is primarily due to product of combustion, as is the case of internal combustion engines and the PM is released to the atmosphere through the tail. Non-exhaust PM sources can be classified as sources such as emissions due to brake wear, tyre wear, road surface wear and resuspension. Both exhaust and non-exhaust sources generate PM of various sizes and shapes that has an impact on our health. Strict legislations by authorities have led to reduced exhaust emissions; however, due to the nature of complexity of PM generation by non-exhaust sources, effective control of non-exhaust emission still needs to be developed. Thus, as exhaust emissions are being controlled, non-exhaust is becoming a significant source of PM emission. The present paper reviews work done by previous researchers on non-exhaust PM and specifically, brake wear from road transport systems as this is one of the most important non-exhaust source of PM in the environment. The finding of the paper would be beneficial to policy makers and researchers.

  8. Should School Nurses Wear Uniforms? (United States)

    Journal of School Health, 2001


    This 1958 paper questions whether school nurses should wear uniforms (specifically, white uniforms). It concludes that white uniforms are often associated with the treatment of ill people, and since many people have a fear reaction to them, they are not necessary and are even undesirable. Since school nurses are school staff members, they should…

  9. Recreational SCUBA divers' willingness to pay for marine biodiversity in Barbados. (United States)

    Schuhmann, Peter W; Casey, James F; Horrocks, Julia A; Oxenford, Hazel A


    The use of natural resources and the services they provide often do not have an explicit price and are therefore undervalued in decision-making, leading to environmental degradation. To 'monetize' the benefits from these services requires the use of non-market valuation techniques. Using a stated preference survey of recreational divers in Barbados conducted between 2007 and 2009, the economic value of marine biodiversity to recreational SCUBA divers in Barbados was estimated. In addition to a variety of demographic variables, divers were asked about their level of experience, expenditures related to travel and diving, and encounters with fish and sea turtles. Divers then completed a choice experiment, selecting between alternative dives with varying characteristics including price, crowding, fish diversity, encounters with sea turtles, and coral cover. Results indicate that divers in Barbados have a clear appreciation of reef quality variables. Willingness to pay for good coral cover, fish diversity and presence of sea turtles is significantly higher than prices paid for dives. In general, divers valued reef attributes similarly, although their appreciation of low density of divers at a site and high coral cover varied with prior diving experience. The results of this study demonstrate the economic value generated in Barbados by the recreational SCUBA diving industry and highlight the potential for substantial additional economic contributions with improvements to the quality of a variety of reef attributes. These results could inform management decisions regarding reef use and sea turtle conservation, and could aid in the development of informed 'win-win' policies aimed at maximizing returns from diving while reducing negative impacts often associated with tourism activities. Copyright © 2013 Elsevier Ltd. All rights reserved.

  10. Scuba diving injuries among Divers Alert Network members 2010-2011. (United States)

    Ranapurwala, Shabbar I; Bird, Nicholas; Vaithiyanathan, Pachabi; Denoble, Petar J


    Scuba diving injuries vary greatly in severity and prognosis. While decompression sickness (DCS) and arterial gas embolism can be tracked easily, other forms of diving injury remain unaccounted for. The purpose of this paper is to assess rates of overall self-reported scuba-diving-related injuries, self-reported DCS-like symptoms, and treated DCS and their association with diver certification level, diving experience and demographic factors. We analyzed self-reported data from a Divers Alert Network membership health survey conducted during the summer of 2011. Poisson regression models with scaled deviance were used to model the relative rates of reported injuries. Models were adjusted for sex, age, body mass index (BMI) and average annual dives, based on the bias-variance tradeoff. The overall rate of diving-related injury was 3.02 per 100 dives, self-reported DCS symptoms was 1.55 per 1,000 dives and treated DCS was 5.72 per 100,000 dives. Diving-related injury and self-reported DCS symptom rates decreased for higher diver certification levels, increasing age, increasing number of average annual dives and for men; they increased for increasing BMI. Diving injury rates may be higher than previously thought, indicating a greater burden on the diving community. Self-reported DCS-like symptoms are a small fraction of all dive-related injuries and those receiving treatment for DCS are an even smaller fraction. The small number of divers seeking treatment may suggest the mild nature and a tendency towards natural resolution for most injuries.

  11. SCUBA and HIRES Results for Protostellar Cores in the MON OB1 Dark Cloud (United States)

    Wolf-Chase, G.; Moriarty-Schieven, G.; Fich, M.; Barsony, M.


    We have used HIRES-processing of IRAS data and point-source modelling techniques (Hurt & Barsony 1996; O'Linger 1997; Barsony et al. 1998), together with submillimeter continuum imaging using the Submillimeter Common-User Bolometer Array (SCUBA) on the 15-meter James Clerk Maxwell Telescope (JCMT), to search CS cores in the Mon OB1 dark cloud (Wolf-Chase, Walker, & Lada 1995; Wolf-Chase & Walker 1995) for deeply embedded sources. These observations, as well as follow-up millimeter photometry at the National Radio Astronomy Observatory (NRAO) 12-meter telescope on Kitt Peak, have lead to the identification of two Class 0 protostellar candidates, which were previously unresolved from two brighter IRAS point sources (IRAS 06382+0939 & IRAS 06381+1039) in this cloud. Until now, only one Class 0 object had been confirmed in Mon OB1; the driving source of the highly-collimated outflow NGC 2264 G (Ward-Thompson, Eiroa, & Casali 1995; Margulis et al. 1990; Lada & Fich 1996), which lies well outside the extended CS cores. One of the new Class 0 candidates may be an intermediate-mass source associated with an H_2O maser, and the other object is a low-mass source which may be associated with a near-infrared jet, and possibly with a molecular outflow. We report accurate positions for the new Class 0 candidates, based on the SCUBA images, and present new SEDs for these sources, as well as for the brighter IRAS point sources. A portion of this work was performed while GWC held a President's Fellowship from the University of California. MB and GWC gratefully acknowledge financial support from MB's NSF CAREER Grant, AST97-9753229.

  12. A SCUBA imaging survey of ultracompact HII regions. The environments of massive star formation (United States)

    Thompson, M. A.; Hatchell, J.; Walsh, A. J.; MacDonald, G. H.; Millar, T. J.


    We present a SCUBA submillimetre (450 and 850 μm) survey of the environment of 105 IRAS point sources, selected from the Wood & Churchwell (1989a) and Kurtz et al. (1994) radio ultracompact (UC) Hii region surveys. We detected a total of 155 sub-mm clumps associated with the IRAS point sources and identified three distinct types of object: ultracompact cm-wave sources that are not associated with any sub-mm emission (sub-mm quiet objects), sub-mm clumps that are associated with ultracompact cm-wave sources (radio-loud clumps); and sub-mm clumps that are not associated with any known ultracompact cm-wave sources (radio-quiet clumps). 90% of the sample of IRAS point sources were found to be associated with strong sub-mm emission. We consider the sub-mm colours, morphologies and distance-scaled fluxes of the sample of sub-mm clumps and show that the sub-mm quiet objects are unlikely to represent embedded UC Hii regions unless they are located at large heliocentric distances. Many of the 2.5 arcmin SCUBA fields contain more than one sub-mm clump, with an average number of companions (the companion clump fraction) of 0.90. The clumps are more strongly clustered than other candidate HMPOs and the mean clump surface density exhibits a broken power-law distribution with a break at 3 pc. We demonstrate that the sub-mm and cm-wave fluxes of the majority of radio-loud clumps are in excellent agreement with the standard model of ultracompact Hii regions. We speculate on the nature of the radio-quiet sub-mm clumps and, whilst we do not yet have sufficient data to conclude that they are in a pre-UC Hii region phase, we argue that their characteristics are suggestive of such a stage.

  13. The Influence of Different Types of Physical Activity on The Redox Status of Scuba Divers

    Directory of Open Access Journals (Sweden)

    Radojevic-Popovic Radmila


    Full Text Available The effect of scuba diving on ROS production and oxidative stress compared to that of other recreational activities is still poorly understood. The aim of this study was to assess the influence of different types of physical activity on the redox status of scuba divers by testing the pro- and anti-oxidative parameters immediately before and after different types of physical load. The prevalence study included 10 professional police divers. All examinees were male, 32 ± 5.1 years of age, well-trained, and with a minimum of five to a maximum of 20 years of diving experience. The study was divided into three experimental protocols: 1 an exercise test (at atmospheric pressure, 2 an at sea dive (30 meters for 30 minutes, and 3 a dive into river current (10 meters for 30 minutes. Immediately before and after the load test of the divers at atmospheric pressure and immediately before and after the dive, blood samples were taken to determine the values of the following pro-oxidant markers: O2−, H2O2, NO2− and TBARS, as well as antioxidant enzymes (SOD and CAT. A comparison of the results before and after physical activity for all three protocols revealed a significant increase in values for NO2−, O2−, H2O2 and CAT after physical activity. It can be concluded that the values of all oxidative stress markers depend on the season of the year in which the research is conducted or on the frequency of dives and degree of physical exertion during this period of the year.

  14. The JCMT Gould Belt Survey: first results from SCUBA-2 observations of the Cepheus Flare region (United States)

    Pattle, K.; Ward-Thompson, D.; Kirk, J. M.; Di Francesco, J.; Kirk, H.; Mottram, J. C.; Keown, J.; Buckle, J.; Beaulieu, S. F.; Berry, D. S.; Broekhoven-Fiene, H.; Currie, M. J.; Fich, M.; Hatchell, J.; Jenness, T.; Johnstone, D.; Nutter, D.; Pineda, J. E.; Quinn, C.; Salji, C.; Tisi, S.; Walker-Smith, S.; Hogerheijde, M. R.; Bastien, P.; Bresnahan, D.; Butner, H.; Chen, M.; Chrysostomou, A.; Coudé, S.; Davis, C. J.; Drabek-Maunder, E.; Duarte-Cabral, A.; Fiege, J.; Friberg, P.; Friesen, R.; Fuller, G. A.; Graves, S.; Greaves, J.; Gregson, J.; Holland, W.; Joncas, G.; Knee, L. B. G.; Mairs, S.; Marsh, K.; Matthews, B. C.; Moriarty-Schieven, G.; Mowat, C.; Rawlings, J.; Richer, J.; Robertson, D.; Rosolowsky, E.; Rumble, D.; Sadavoy, S.; Thomas, H.; Tothill, N.; Viti, S.; White, G. J.; Wouterloot, J.; Yates, J.; Zhu, M.


    We present observations of the Cepheus Flare obtained as part of the James Clerk Maxwell Telescope (JCMT) Gould Belt Legacy Survey (GBLS) with the SCUBA-2 instrument. We produce a catalogue of sources found by SCUBA-2, and separate these into starless cores and protostars. We determine masses and densities for each of our sources, using source temperatures determined by the Herschel Gould Belt Survey. We compare the properties of starless cores in four different molecular clouds: L1147/58, L1172/74, L1251 and L1228. We find that the core mass functions for each region typically show shallower-than-Salpeter behaviour. We find that L1147/58 and L1228 have a high ratio of starless cores to Class II protostars, while L1251 and L1174 have a low ratio, consistent with the latter regions being more active sites of current star formation, while the former are forming stars less actively. We determine that if modelled as thermally supported Bonnor-Ebert spheres, most of our cores have stable configurations accessible to them. We estimate the external pressures on our cores using archival 13CO velocity dispersion measurements and find that our cores are typically pressure confined, rather than gravitationally bound. We perform a virial analysis on our cores, and find that they typically cannot be supported against collapse by internal thermal energy alone, due primarily to the measured external pressures. This suggests that the dominant mode of internal support in starless cores in the Cepheus Flare is either non-thermal motions or internal magnetic fields.

  15. The SCUBA-2 Cosmology Legacy Survey: 850 μm maps, catalogues and number counts (United States)

    Geach, J. E.; Dunlop, J. S.; Halpern, M.; Smail, Ian; van der Werf, P.; Alexander, D. M.; Almaini, O.; Aretxaga, I.; Arumugam, V.; Asboth, V.; Banerji, M.; Beanlands, J.; Best, P. N.; Blain, A. W.; Birkinshaw, M.; Chapin, E. L.; Chapman, S. C.; Chen, C.-C.; Chrysostomou, A.; Clarke, C.; Clements, D. L.; Conselice, C.; Coppin, K. E. K.; Cowley, W. I.; Danielson, A. L. R.; Eales, S.; Edge, A. C.; Farrah, D.; Gibb, A.; Harrison, C. M.; Hine, N. K.; Hughes, D.; Ivison, R. J.; Jarvis, M.; Jenness, T.; Jones, S. F.; Karim, A.; Koprowski, M.; Knudsen, K. K.; Lacey, C. G.; Mackenzie, T.; Marsden, G.; McAlpine, K.; McMahon, R.; Meijerink, R.; Michałowski, M. J.; Oliver, S. J.; Page, M. J.; Peacock, J. A.; Rigopoulou, D.; Robson, E. I.; Roseboom, I.; Rotermund, K.; Scott, Douglas; Serjeant, S.; Simpson, C.; Simpson, J. M.; Smith, D. J. B.; Spaans, M.; Stanley, F.; Stevens, J. A.; Swinbank, A. M.; Targett, T.; Thomson, A. P.; Valiante, E.; Wake, D. A.; Webb, T. M. A.; Willott, C.; Zavala, J. A.; Zemcov, M.


    We present a catalogue of ˜3000 submillimetre sources detected (≥3.5σ) at 850 μm over ˜5 deg2 surveyed as part of the James Clerk Maxwell Telescope (JCMT) SCUBA-2 Cosmology Legacy Survey (S2CLS). This is the largest survey of its kind at 850 μm, increasing the sample size of 850 μm selected submillimetre galaxies by an order of magnitude. The wide 850 μm survey component of S2CLS covers the extragalactic fields: UKIDSS-UDS, COSMOS, Akari-NEP, Extended Groth Strip, Lockman Hole North, SSA22 and GOODS-North. The average 1σ depth of S2CLS is 1.2 mJy beam-1, approaching the SCUBA-2 850 μm confusion limit, which we determine to be σc ≈ 0.8 mJy beam-1. We measure the 850 μm number counts, reducing the Poisson errors on the differential counts to approximately 4 per cent at S850 ≈ 3 mJy. With several independent fields, we investigate field-to-field variance, finding that the number counts on 0.5°-1° scales are generally within 50 per cent of the S2CLS mean for S850 > 3 mJy, with scatter consistent with the Poisson and estimated cosmic variance uncertainties, although there is a marginal (2σ) density enhancement in GOODS-North. The observed counts are in reasonable agreement with recent phenomenological and semi-analytic models, although determining the shape of the faint-end slope (S850 10 mJy there are approximately 10 sources per square degree, and we detect the distinctive up-turn in the number counts indicative of the detection of local sources of 850 μm emission, and strongly lensed high-redshift galaxies. All calibrated maps and the catalogue are made publicly available.

  16. Imaging the environment of a z = 6.3 submillimeter galaxy with SCUBA-2

    Energy Technology Data Exchange (ETDEWEB)

    Robson, E. I.; Holland, W. S. [United Kingdom Astronomy Technology Centre, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Ivison, R. J. [European Space Observatory, Karl Schwarzschild Strasse 2, D-85748 Garching (Germany); Smail, Ian [Institute for Computational Cosmology, Durham University, South Road, Durham DH1 3LE (United Kingdom); Geach, J. E. [Centre for Astrophysics Research, University of Hertfordshire, Hatfield AL10 9AB (United Kingdom); Gibb, A. G. [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada); Riechers, D. [Astronomy Department, Cornell University, Ithaca, NY 14853 (United States); Ade, P. A. R. [Astronomy and Instrumentation Group, Cardiff University, Cardiff, Wales CF10 3XQ (United Kingdom); Bintley, D. [Joint Astronomy Centre, 660 North Ahoku Place, University Park, Hilo, HI 96720 (United States); Bock, J. [Jet Propulsion Laboratory, National Aeronautics and Space Administration, Pasadena, CA 91109 (United States); Chapin, E. L. [XMM-Newton Science Operations Centre, European Space Astronomy Centre, Apartado 79, E-28691 Villaneueva de la Canada, Madrid (Spain); Chapman, S. C. [Department of Physics and Atmospheric Science, Dalhousie University, Coburg Road, Halifax B3H 1A6 (Canada); Clements, D. L. [Astrophysics Group, Imperial College London, Blackett Laboratory, Prince Consort Road, London SW7 2AZ (United Kingdom); Conley, A. [Center for Astrophysics and Space Astronomy, 389 UCB, University of Colorado, Boulder, CO 80309 (United States); Cooray, A. [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Dunlop, J. S. [Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Farrah, D., E-mail: [Department of Physics, Virginia Tech, Blacksburg, VA 24061 (United States); and others


    We describe a search for submillimeter emission in the vicinity of one of the most distant, luminous galaxies known, HerMES FLS3, at z = 6.34, exploiting it as a signpost to a potentially biased region of the early universe, as might be expected in hierarchical structure formation models. Imaging to the confusion limit with the innovative, wide-field submillimeter bolometer camera, SCUBA-2, we are sensitive to colder and/or less luminous galaxies in the surroundings of HFLS3. We use the Millennium Simulation to illustrate that HFLS3 may be expected to have companions if it is as massive as claimed, but find no significant evidence from the surface density of SCUBA-2 galaxies in its vicinity, or their colors, that HFLS3 marks an overdensity of dusty, star-forming galaxies. We cannot rule out the presence of dusty neighbors with confidence, but deeper 450 μm imaging has the potential to more tightly constrain the redshifts of nearby galaxies, at least one of which likely lies at z ≳ 5. If associations with HFLS3 can be ruled out, this could be taken as evidence that HFLS3 is less biased than a simple extrapolation of the Millennium Simulation may imply. This could suggest either that it represents a rare short-lived, but highly luminous, phase in the evolution of an otherwise typical galaxy, or that this system has suffered amplification due to a foreground gravitational lens and so is not as intrinsically luminous as claimed.

  17. Wear performance of laser processed tantalum coatings

    Energy Technology Data Exchange (ETDEWEB)

    Dittrick, Stanley; Balla, Vamsi Krishna; Bose, Susmita; Bandyopadhyay, Amit, E-mail:


    This first generation investigation evaluates the in vitro tribological performance of laser-processed Ta coatings on Ti for load-bearing implant applications. Linear reciprocating wear tests in simulated body fluid showed one order of magnitude less wear rate, of the order of 10{sup -4} mm{sup 3}(N.m){sup -1}, for Ta coatings compared to Ti. Our results demonstrate that Ta coatings can potentially minimize the early-stage bone-implant interface micro-motion induced wear debris generation due to their excellent bioactivity comparable to that of hydroxyapatite (HA), high wear resistance and toughness compared to popular HA coatings. Highlights: {yields} In vitro wear performance of laser processed Ta coatings on Ti was evaluated. {yields} Wear tests in SBF showed one order of magnitude less wear for Ta coatings than Ti. {yields} Ta coatings can minimize early-stage micro-motion induced wear debris generation.

  18. The Delamination Theory of Wear - III (United States)


    approximate, it shows excellent agreement with the above postulate and with experimental observations of wear. It was shown that void nucleation is...purposes: to predict wear arnd to reduce wear, Mathematical modelo are necessary in order to predict wear 40 qualitatively. They are also useful in the...the substrate and on the physical and chemical properties of the materials involved, There are a number of excellent references on coating techniques

  19. Complications Caused by Contact Lens Wearing


    Beljan, Jasna; Beljan, Kristina; Beljan, Zdravko


    Complications in wearing contact lenses are very rare and caused by poor maintenance, over-extended wear and wearing of contact lenses in a polluted environment. Regular control by a professional person can efficiently reduce the number of complications. This paper describes the most common risks factors for complications, and complications of wearing contact lenses with the classification according to the anatomic parts of the eye: eyelids, tear film, limbus, corneal epithelium, corneal stro...

  20. The Synergy between Scuba Diving and Household Behaviour: Testing Plastic and Food Waste "The use of natural habitats for tourism education"


    Soares Mota, Luís Cândido


    The activity of scuba diving is used for studying behaviours of U.S. visitors to a popular tourist destination in Mexico. The impact created by human activity can produce marine debris and therefore affect the marine environment. The subpopulation of 181 divers was tested for their current household practices regarding discarding plastic and food waste, providing quantitative statistics for divers’ referential behaviour. Prior to partaking in scuba diving, certified, trainee, and “one-day-exp...

  1. Needs and challenges in precision wear measurement

    Energy Technology Data Exchange (ETDEWEB)

    Blau, P.J.


    Accurate, precise wear measurements are a key element in solving both current wear problems and in basic wear research. Applications range from assessing durability of micro-scale components to accurate screening of surface treatments and thin solid films. Need to distinguish small differences in wear tate presents formidable problems to those who are developing new materials and surface treatments. Methods for measuring wear in ASTM standard test methods are discussed. Errors in using alterate methods of wear measurement on the same test specimen are also described. Human judgemental factors are a concern in common methods for wear measurement, and an experiment involving measurement of a wear scar by ten different people is described. Precision in wear measurement is limited both by the capabilities of the measuring instruments and by the nonuniformity of the wear process. A method of measuring wear using nano-scale indentations is discussed. Current and future prospects for incorporating advanced, higher-precision wear measurement methods into standards are considered.

  2. Fundamental study of the effect of high-salinity brines on the friction and wear properties of stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Pearsall, K.J.; Govin, G.; Eliezer, Z.; Bebout, D.G.; Bachman, A.L. (eds.)


    Friction and corrosive wear experiments were performed in a geothermal-geopressured brine and in a 3% NaCl solution in a friction and wear electrolytic cell. The formation of a passive film on 304 stainless steel has a beneficial effect on the magnitude of the coefficient of friction. When pits are electrochemically introduced in the passive film, the friction coefficient becomes even lower than the passive coefficient of friction in the 3% NaCl, but does not significantly change for the brine. The effect of corrosive wear on the surface film is more difficult to assess. Auger spectroscopy was performed on wear surfaces (subjected to both electrochemical and mechanical action) and non-wear surfaces (subjected only to electrochemical action). The surface films formed in 3% NaCl in the non-wear and wear areas including pits consisted of Cr, Fe and Ni in ratios consistent to the bulk material plus 0. In brine the surface film consists of the same elements as above; however, the surface film associated with the non-wear area and the wear area pit show a Cr depletion. Yet, the wear area film is consistent with bulk as in the case of the 3% NaCl.

  3. Effects of sintering temperatures on microstructure and wear resistance of iron-silica composite (United States)

    Amir, Adibah; Mamat, Othman


    Ceramic particle reinforced into metal base matrix composite has been reported to produce higher strength and wear resistance than its alloys because the ceramic phases can strongly resist abrasion. In this study the iron matrix was reinforced with two compositions of 20 and 25 wt. % fine silica particles. The compacts were produced by using powder metallurgy fabrication technique and sintered at three sintering temperatures: 1000, 1100 and 1200°C. Effects of various sintering temperatures on microstructures and the composite's wear resistance were evaluated via optical and SEM microscopy. Both compositions were also subjected to ball-on-disk wear test. The results showed the reinforcement weight fraction of 20 wt.% of silica and sintering temperature at 1100°C exhibited better result, in all aspects. It possessed higher mechanical properties, it's microstructure revealed most intact reinforcing region and it displayed higher wear resistance during wear test.

  4. Wear resistance of hydrophobic surfaces (United States)

    Martinez, MA; Abenojar, J.; Pantoja, M.; López de Armentia, S.


    Nature has been an inspiration source to develop artificial hydrophobic surfaces. During the latest years the development of hydrophobic surfaces has been widely researched due to their numerous ranges of industrial applications. Industrially the use of hydrophobic surfaces is being highly demanded. This is why many companies develop hydrophobic products to repel water, in order to be used as coatings. Moreover, these coating should have the appropriated mechanical properties and wear resistance. In this work wear study of a hydrophobic coating on glass is carried out. Hydrophobic product used was Sika Crystal Dry by Sika S.A.U. (Alcobendas, Spain). This product is currently used on car windshield. To calculate wear resistance, pin-on-disk tests were carried out in dry and water conditions. The test parameters were rate, load and sliding distance, which were fixed to 60 rpm, 5 N and 1000 m respectively. A chamois was used as pin. It allows to simulate a real use. The friction coefficient and loss weight were compared to determinate coating resistance

  5. Comparative analysis of free and scuba diving for benthopelagic and cryptic fish species associated with rocky reefs

    Directory of Open Access Journals (Sweden)

    Rodolfo Gutterres Giordano


    Full Text Available This work aimed to assess, through experimental comparisons between free and scuba diving performed in Arraial do Cabo city, RJ, Brazil, the abundances of Scartella cristata e Chaetodon striatus -two reef fish species of contrasting behaviors- in different depth layers of sheltered and exposed rocky reefs. C. striatus was homogeneously distributed through all the depth strata (0-10 m and scuba diving should be preferred over free diving to assess the abundance of this species at exposed rocky shores, undergoing continuous effects of waves and winds. Both free and scuba diving can be used indistinctly and with no data biases to appraise the abundances of C. striatus in non-turbulent reefs or in shallow zones (i.e., ≤ 5 m of exposed reefs, and, for S. cristata, in all depth layers (i.e., up to 10 m of both sheltered and exposed reefs. Although the abundances of S. cristata did not significantly differ between free and scuba diving, contrasting with most previous studies that stressed the risk of the first method to underestimate the abundance of small and cryptic species, it should be considered that the previous experience of the diver and the nature of our study (i.e., focused specifically on a cryptic species may have contributed to our findings. Further studies are, however, necessary to test our findings in different conditions (i.e., depths, hydrodynamic characteristics, and habitat complexity and for other tropical reef fish species, in order to increase the truthfulness of underwater visual census and reduce the risk of failure of fish conservation and management programs potentially based on biased data.

  6. Conjunctival epithelial flap in continuous contact lens wear. (United States)

    Graham, Andrew D; Truong, Tan N; Lin, Meng C


    Composed of sheets of cells detached from the underlying conjunctiva, conjunctival epithelial flap (CEF) is a recently reported phenomenon associated with contact lens wear with potential consequences for ocular health. Although CEF is generally asymptomatic, it is not known to what extent it might increase the longer-term risk of discomfort, inflammatory response, or infection. In this study, we use survival analysis methods to obtain unbiased estimates of the probability of developing CEF, the mean survival time free of CEF, and the effects of age, gender, ethnicity, and contact lens type. Two hundred four subjects were recruited for a continuous wear (CW) study of silicone hydrogel (SiH) and gas permeable (GP) contact lenses. Subjects were examined by optometrists throughout contact lens adaptation and CW periods. Statistical methods included the Kaplan-Meier nonparametric estimator of the survival function and the Cox proportional hazards model for estimating the relative effects of covariates. Of the 204 subjects, 72 (35%) developed CEF. In 64% of cases, CEFs were observed bilaterally. The majority of cases (90.3%) presented with CEF in the superior conjunctiva. Mean survival time free of CEF was longer for GP lenses (94.3 days) than for SiH lenses (76.5 days), and the probability of developing CEF was significantly greater for SiH lenses (p = 0.002). Although there was some evidence that women and non-Asians remain free of CEF longer, the effects of age, gender, and ethnicity were not statistically significant. There was a significantly increased risk of CEF in subjects wearing SiH lenses, compared with GP lenses. Subjects wearing SiH lenses remained free of CEF for a shorter time on average. Further study is needed to determine whether the increased incidence of CEF in CW with SiH lenses poses an increased risk of adverse ocular response or infection.

  7. Predicting extended wear complications from overnight corneal swelling. (United States)

    Graham, A D; Fusaro, R E; Polse, K A; Lin, M C; Giasson, C J


    To examine the hypothesis that the corneal overnight swelling response (ONSR) is a predictor of ocular complications in contact lens extended wear (EW). The Berkeley Contact Lens Extended Wear Study (CLEWS) was a randomized, concurrently controlled clinical trial in which more than 200 subjects in EW with rigid gas-permeable (RGP) lenses were observed for 1 year. After adapting to EW, subjects were randomized to either medium or high oxygen-permeable (Dk) RGP lenses and underwent clinical assessments, keratometry, and corneal pachometry at 3-month intervals. The ONSR was directly related to lens Dk (P = 0.01) and exhibited substantial variability across subjects. The probability of remaining free of complications over time was not significantly lower for subjects with a mild ONSR compared with those with greater edema (P = 0.84). The risk of development of keratopathy was not significantly related to the ONSR (relative risk = 1.00). The corneal ONSR is not a good predictor of ocular complications in 1 year of RGP EW. Lenses that cause little or no corneal edema are not necessarily safer for overnight wear.

  8. The Hawaii SCUBA-2 Lensing Cluster Survey: Radio-detected Submillimeter Galaxies in the HST Frontier Fields (United States)

    Hsu, Li-Yen; Desai, Vandana; Murphy, Eric J.; Cowie, Lennox L.; Heywood, Ian; Momjian, Emmanuel; Barger, Amy J.; Smail, Ian


    In this second paper of the Hawaii SCUBA-2 Lensing Cluster Survey series, we cross-match SCUBA-2 maps with 3 and 6 GHz images from the Janksy-VLA Frontier Fields Legacy Survey for three cluster fields, MACS J0416.1-2403, MACS J0717.5+3745, and MACS J1149.5+2223. Within the HST coverage, 14 out of 44 850 μm sources have 3 GHz counterparts, five of which are also detected at 6 GHz. The 850 μm flux densities of these detected sources span from 0.7 to 4.4 mJy after correcting for lensing amplification. The median redshift of the sample is z={1.28}-0.09+0.07, much lower than the typical redshifts (z = 2-3) of brighter submillimeter galaxies (SMGs) in the literature. In addition, we find that our sources have lower dust temperatures than those of the brighter SMGs. This is also confirmed by an analysis of the ratio between infrared star-formation rate and 850 μm flux density. However, these 14 sources may not represent the general submillimeter population at the same flux range, given that the SCUBA-2 sources without radio counterparts are likely at higher redshifts. Detection of these sources would require deeper radio images or submillimeter interferometry.

  9. Wear resistance of four types of vacuum-formed retainer materials: a laboratory study. (United States)

    Raja, Taiyub A; Littlewood, Simon J; Munyombwe, Theresa; Bubb, Nigel L


    To investigate the resistance to wear of four different vacuum-formed retainer (VFR) materials: Essix C+, Essix ACE, Duran, and Tru-Tain. Essix C+ is a polypropylene polymer; the other materials are polyethylene co-polymers. The study was undertaken at the Leeds Dental Institute, Leeds, UK, with 26 samples in each group. The specimens were vacuum-formed according to the manufacturers' guidelines, and a custom-made wear-simulation machine was used to conduct the test. Each specimen was subjected to 1000 cycles of the wear simulation, with steatite balls as the antagonist material. The resistance to wear of the VFR materials was evaluated by measuring the maximum wear depth using noncontact, three-dimensional surface profilometry. The wear depth was given in micrometers. The median wear depth was 63.20 µm for the Essix C+ group, 7.88 µm for the Essix ACE group, 9.75 µm for the Duran group, and 12.08 µm for the Tru-Tain group. The Kruskal-Wallis test to compare the four VFR materials detected a statistically significant difference between the groups (P materials-Essix ACE, Duran, and Tru-Tain-exhibited significantly less wear than the polypropylene material, Essix C+.

  10. Evaluation of the wear resistance of new nanocomposite resin restorative materials. (United States)

    Yesil, Zeynep Duymus; Alapati, Satish; Johnston, William; Seghi, Robert R


    The use of composite resins for the restoration of posterior teeth is popular because of the improved performance and appearance of these materials. Wear resistance continues to be of particular importance when restoring large occlusal areas in posterior teeth. The purpose of this study was to evaluate the relative wear characteristics of 2 recently introduced nanofiller-based composite resins (Filtek Supreme, Premise) and compare them to the more traditional microhybrid (Point 4) and microfill (Heliomolar RO) materials that have been used for many years. Six specimens (2 mm thick and 15 mm in diameter) of each material were subjected to 3-body wear tests using the Oregon Health Sciences University Oral Wear Simulator to produce abrasive wear and attrition for all specimens using human enamel as the opposing cusp. Profilometric tracings of the worn surfaces were used to determine the relative abrasive wear, attrition wear, and roughness (Ra) of the composite resin substrate. The mean diameter of the antagonist enamel wear facets was determined under a measuring microscope. Qualitative SEM analysis was also used to assess the surface appearance of the resulting enamel and composite resin wear facets. The data were analyzed by 1-way ANOVA and Tukey's multiple range post hoc test (alpha=.05). The results indicated that the composite resin type did not significantly affect the amount of measured attrition (P=.15) but did significantly affect abrasive wear (P=.02). The conventional microfill composite resin (Heliomolar RO) exhibited significantly less abrasive wear than the nanohybrid material (Premise). There was no significant difference in the average size of the opposing enamel wear facet generated by the different composite resin materials. Heliomolar RO resulted in a significantly rougher surface within the wear track than either nanohybrid composite resin (Premise) or microhybrid composite resin (Point 4) but was not significantly different than nanofilled


    Energy Technology Data Exchange (ETDEWEB)

    Chen, Chian-Chou; Smail, Ian; Ma, Cheng-Jiun; Simpson, James M.; Swinbank, A. Mark [Centre for Extragalactic Astronomy, Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom); Ivison, Rob J.; Arumugam, Vinodiran; Mortlock, Alice; Dunlop, James S.; Michałowski, Michał J. [Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Almaini, Omar; Conselice, Christopher J.; Hartley, Will G. [University of Nottingham, School of Physics and Astronomy, Nottingham, NG7 2RD (United Kingdom); Geach, James E. [Center for Astrophysics Research, Science and Technology Research Institute, University of Hertfordshire, Hatfield AL10 9AB (United Kingdom); Simpson, Chris [Astrophysics Research Institute, Liverpool John Moores University, Liverpool Science Park, 146 Brownlow Hill, Liverpool L3 5RF (United Kingdom); Aretxaga, Itziar [Instituto Nacional de Astrofísica, Óptica y Electrónica (INAOE), Luis Enrique Erro 1, Sta. Ma. Tonantzintla, Puebla (Mexico); Blain, Andrew [Physics and Astronomy, University of Leicester, Leicester, LE1 7RH (United Kingdom); Chapman, Scott C. [Department of Physics and Atmospheric Science, Dalhousie University, 6310 Coburg Road, Halifax, NS B3H 4R2 (Canada); Farrah, Duncan [Department of Physics, Virginia Tech, Blacksburg, VA 24061 (United States); Halpern, Mark [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada); and others


    We present multiwavelength identifications for the counterparts of 1088 submillimeter sources detected at 850 μm in the SCUBA-2 Cosmology Legacy Survey study of the UKIRT Infrared Deep Sky Survey-Ultra-Deep Survey (UDS) field. By utilizing an Atacama Large Millimeter Array (ALMA) pilot study on a subset of our bright SCUBA-2 sample as a training set, along with the deep optical–near-infrared (OIR) data available in this field, we develop a novel technique, Optical–IR Triple Color (OIRTC), using z − K, K − [3.6], [3.6] − [4.5] colors to select the candidate submillimeter galaxy (SMG) counterparts. By combining radio identification and the OIRTC technique, we find counterpart candidates for 80% of the Class = 1 ≥ 4σ SCUBA-2 sample, defined as those that are covered by both radio and OIR imaging and the base sample for our scientific analyses. Based on the ALMA training set, we expect the accuracy of these identifications to be 82% ± 20%, with a completeness of 69% ± 16%, essentially as accurate as the traditional p-value technique but with higher completeness. We find that the fraction of SCUBA-2 sources having candidate counterparts is lower for fainter 850 μm sources, and we argue that for follow-up observations sensitive to SMGs with S{sub 850} ≳ 1 mJy across the whole ALMA beam, the fraction with multiple counterparts is likely to be >40% for SCUBA-2 sources at S{sub 850} ≳ 4 mJy. We find that the photometric redshift distribution for the SMGs is well fit by a lognormal distribution, with a median redshift of z = 2.3 ± 0.1. After accounting for the sources without any radio and/or OIRTC counterpart, we estimate the median redshift to be z = 2.6 ± 0.1 for SMGs with S{sub 850} > 1 mJy. We also use this new large sample to study the clustering of SMGs and the far-infrared properties of the unidentified submillimeter sources by stacking their Herschel SPIRE far-infrared emission.

  12. The measurement of enamel wear by four toothpastes. (United States)

    Joiner, A; Pickles, M J; Lynch, S; Cox, T F


    To determine the enamel abrasivity of three whitening toothpastes and a silica toothpaste and to measure the brushing forces used. Polished human enamel blocks were indented with a Knoop diamond and attached to dentures of adult volunteers. The blocks were brushed ex vivo, twice per day with either a whitening toothpaste containing Perlite (White System), a commercial whitening toothpaste (A and B) or a silica toothpaste. After four and twelve-weeks, one block per subject was removed and the Knoop indent remeasured. From the changes in the indent length, the amount of enamel wear was calculated. The mean enamel wear (sd) for White System, silica toothpaste, whitening toothpaste A and B after four-weeks was 0.14 (0.15), 0.09 (0.16), 0.14 (0.12) and 0.89 (0.93) and after twelve-weeks was 0.24 (0.21), 0.37 (0.73), 0.36 (0.52) and 1.04 (0.98) microm respectively. After four-weeks, the differences in enamel wear between whitening toothpaste B and all other toothpastes were of statistical significance (p whitening toothpastes did not give significantly more enamel wear than a silica toothpaste after twelve-weeks in situ with ex vivo brushing.

  13. Role of plastic deformation in wear of copper and copper - 10-percent-aluminum alloy in cryogenic fuels (United States)

    Bill, R. C.; Wisander, D. W.


    High-purity copper specimens and a copper-aluminum (10%) alloy specimen were subjected to sliding against Type 440 C in cryogenic fuel environments. It was found that virtually all wear occurred by the plastic deformation of a recrystallized layer extending to about 10 micrometers below the wear scar surface of the copper or copper alloy. The wear debris was in the form of a layered structure adhering to the exit region of the wear scar. Measurements on the high purity copper specimens indicated that the wear rate was proportional to the applied load and to the sliding velocity squared. A physical model of the wear process is proposed to account for these observations.

  14. Epilepsy, scuba diving and risk assessment. Near misses and the need for ongoing vigilance. (United States)

    Smart, David; Lippmann, John


    There is ongoing debate about the safety of scuba diving for individuals with a history of epilepsy. An in-water seizure is highly likely to be fatal. Recommendations for fitness to dive vary with some regarding epilepsy as an absolute contraindication to diving (South Pacific Underwater Medicine Society) and others permitting diving under strict criteria (United Kingdom Sport Diving Medical Committee) with diving to be postponed for a period of three to five years without seizures. Long-term follow up of people with epilepsy shows that at least one-third will have a recurrence and that the risk remains elevated for many years. We present three cases where individuals with a history of epilepsy (or likely epilepsy) almost fell through the cracks of health risk assessment, two with near-fatal consequences. These cases inform the on-going debate about fitness to dive for those with current or past epilepsy, and highlight the importance of education for doctors, dive professionals and divers about the risks associated with epilepsy and diving.

  15. User fees across ecosystem boundaries: Are SCUBA divers willing to pay for terrestrial biodiversity conservation? (United States)

    Roberts, Michaela; Hanley, Nick; Cresswell, Will


    While ecological links between ecosystems have been long recognised, management rarely crosses ecosystem boundaries. Coral reefs are susceptible to damage through terrestrial run-off, and failing to account for this within management threatens reef protection. In order to quantify the extent to that coral reef users are willing to support management actions to improve ecosystem quality, we conducted a choice experiment with SCUBA divers on the island of Bonaire, Caribbean Netherlands. Specifically, we estimated their willingness to pay to reduce terrestrial overgrazing as a means to improve reef health. Willingness to pay was estimated using the multinomial, random parameter and latent class logit models. Willingness to pay for improvements to reef quality was positive for the majority of respondents. Estimates from the latent class model determined willingness to pay for reef improvements of between $31.17 - $413.18/year, dependent on class membership. This represents a significant source of funding for terrestrial conservation, and illustrates the potential for user fees to be applied across ecosystem boundaries. We argue that such across-ecosystem-boundary funding mechanisms are an important avenue for future investigation in many connected systems. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. VizieR Online Data Catalog: SCUBA-2 galaxies in 850um survey (Koprowski+, 2016) (United States)

    Koprowski, M. P.; Dunlop, J. S.; Michalowski, M. J.; Roseboom, I.; Geach, J. E.; Cirasuolo, M.; Aretxaga, I.; Bowler, R. A. A.; Banerji, M.; Bourne, N.; Coppin, K. E. K.; Chapman, S.; Hughes, D. H.; Jenness, T.; McLure, R. J.; Symeonidis, M.; van der Werf, P.


    We used the deep 850um and 450um S2CLS imaging of the central ~=150arcmin2 of the COSMOS/UltraVISTA field, coincident with the Spitzer SEDS (Ashby et al., 2013, Cat. J/ApJ/769/80) and HST CANDELS (Grogin et al., 2011ApJS..197...35G) imaging. The observations were taken with SCUBA-2 mounted on the JCMT between October 2011 and March 2013, reaching depths of σ850~=0.25mJy and σ450~=1.5mJy (Geach et al., 2013MNRAS.432...53G, Roseboom et al., 2013, Cat. J/MNRAS/436/430, Geach et al. 2016 in preparation). In order to enable effective 450um observations, only the very best/dryest conditions were used (i.e. {tau}225GHz<0.05), and to maximise depth the imaging was undertaken with a "daisy" mapping pattern (Bintley et al., 2014, SPIE, 9153, 3). (5 data files).

  17. The development of glossopharyngeal breathing and palatal myoclonus in a 29 year old after scuba diving

    Directory of Open Access Journals (Sweden)

    Thomas AR


    Full Text Available Palatal myoclonus is a rare movement disorder characterized by brief, rhythmic involuntary movements of the soft palate. Palatal myoclonus is further subdivided into “essential palatal tremor” (EPT and “symptomatic palatal tremor” (SPT. EPT is characterized by involvement of the tensor veli palatini, myoclonus that might persist during sleep, as well as ear clicks, usually the patient’s presenting complaint. The MRI and neurological exam are normal in EPT. SPT is characterized by involvement of the levator veli palatini and myoclonus which consistently perseveres during sleep. The MRI shows olivary hypertrophy and clinical features may include ataxia, dysarthria and nystagmus, depending on the size of the lesion1. Glossopharyngeal breathing is a technique used by deep-sea divers to increase lung vital capacity, which is also useful in patients with ventilator dependence from poliomyelitis and Duchenne muscular dystrophy. To date there have been no reported cases of palatal myoclonus and glossopharyngeal breathing occurring simultaneously. We present the case of a 29 year-old female with palatal myoclonus and glossopharyngeal breathing after scuba-diving.

  18. Consideration of Wear Rates at High Velocity (United States)


    Ayers and Second Lieutenant Julius Puentes pro- vided excellent support with dynamic model data, and slipper/rail specimens. Mr. Larry Perkins, Mr...Wear Research . . . . . . . . . . . . . . . . 29 1.10 Key Concepts from the Literature Search . . . . . . . . . 30 II. Metallographic AFIT for physical on-site investigation. 1.4 Description of Wear The literature search revealed that there are many different definitions of wear

  19. The Wear of the Focusing Tube and the Cut-Surface Quality

    Directory of Open Access Journals (Sweden)

    B. Nedic


    Full Text Available The wear of the focusing tube is a very important feature of the abrasive water jet machining. Of all rejected focusing tubes, 85% are worn. Similarly, the age of focusing tube influences the cut geometry and quality of machined surface. With regard to the stated, wearing of the focusing tube is subject of this paper. Focusing tube outlet diameter was measured as well as its influence on the surface quality.

  20. Wear Characteristics of Polymer -Based Composites (United States)

    Şahin, Y.; Mirzayev, H.


    The dry wear of polytetrafluoroethylene (PTFE)-based composites, including bronze-filled composites (B60), glass-filled composites (G15), and carbon-filled composites (C25), produced by the mold casting method were investigated under different sliding conditions. The Taguchi L27 method and the analysis of variance were used to identify the effect of process parameters on the wear of tested materials. Experimental results showed that the wear resistance of G15 polymer composites was better than those of C25 and B60 ones. The specific wear rate decreased with increasing sliding distance and load, but partly decreased with increasing tensile strength.

  1. A comparative study on the wear behavior of a polymer infiltrated ceramic network (PICN) material and tooth enamel. (United States)

    Xu, Zhou; Yu, Ping; Arola, Dwayne D; Min, Jie; Gao, Shanshan


    To investigate the wear mechanisms of a polymer infiltrated ceramic network (PICN) material, to compare its wear behavior with that of tooth enamel, and to provide evidence relevant to its clinical use. The Vickers hardness (HV) and elastic modulus (E) of a commercial PICN material (ENAMIC) and enamel were measured. Reciprocating wear tests were performed under a ball-on-flat configuration. Three wear pairs were explored including ENAMIC and enamel subjected to Si3N4 ball antagonists and ENAMIC subjected to enamel cusp antagonists. The coefficients of Friction (CoFs) were monitored continuously to 5×104 cycles. The wear depth of ENAMIC, enamel specimens and enamel cusps were quantified using white light interferometry, and the wear morphologies were examined using scanning electron microscopy (SEM) to distinguish the wear mechanisms. The HV of ENAMIC is similar to tooth enamel but the E is much lower. For both materials, the CoFs increased sharply in the early stage and then reached plateaus in the later phase. Throughout the cyclic loading history, ENAMIC exhibited larger wear depths than enamel. However, the damage evolution in ENAMIC was similar to that of enamel as the polymer phase was worn preferentially similar to inter-rod enamel, and then the ceramic phase exfoliated from the wear surface akin to enamel rods. The SEM images showed evidence of few cracks within wear tracks of ENAMIC, in comparison to numerous cracks in tooth enamel. ENAMIC has lower wear resistance than tooth enamel, but it exhibits a wear damage mode similar to tooth enamel. Copyright © 2017. Published by Elsevier Ltd.

  2. Long-term clinical results: 3 years of up to 30-night continuous wear of lotrafilcon A silicone hydrogel and daily wear of low-Dk/t hydrogel lenses. (United States)

    Bergenske, Peter; Long, Bill; Dillehay, Sally; Barr, Joseph T; Donshik, Peter; Secor, Glenda; Yoakum, John; Chalmers, Robin L


    To summarize results of a 3-year clinical trial assessing subjective and objective experience with lotrafilcon A silicone hydrogel (SH) lenses for up to 30 nights of continuous wear or low-Dk/t daily-wear (LDW) hydrogel lenses. Nineteen sites dispensed SH lenses to 317 subjects (286 current wearers and 31 new wearers) and 2-week replacement LDW lenses to 81 new wearers in a 3-year study. For the SH cohort, limbal redness, conjunctival redness, and corneal neovascularization improved among 23%, 21%, and 13% of eyes, respectively (PDk/t hydrogel lenses. Many biomicroscopy signs and symptoms worsened among neophytes wearing daily-wear low-Dk/t hydrogel lenses. The use of lotrafilcon A lenses may minimize many ocular changes from soft contact lens wear.

  3. Problems of locomotive wheel wear in fleet replacement

    Directory of Open Access Journals (Sweden)

    L.P. Lingaytis


    Full Text Available Purpose. To conduct a research and find out the causes of defects appearing on the wheel thread of freight locomotives 2М62 and SIEMENS ER20CF. Methodology. To find the ways to solve this problem comparing the locomotive designs and their operating conditions. Findings. After examining the nature of the wheel wear the main difference was found: in locomotives of the 2M62 line wears the wheel flange, and in the locomotives SIEMENS ER20CF – the tread surface. After installation on the 2M62 locomotive the lubrication system of flanges their wear rate significantly decreased. On the new freight locomotives SIEMENS ER20CF the flange lubrication systems of the wheel set have been already installed at the factory, however the wheel thread is wearing. As for locomotives 2M62, and on locomotives SIEMENS ER20CF most wear profile skating wheels of the first wheel set. On both locomotive lines the 2М62 and the SIEMENS ER20CF the tread profile of the first wheel set most of all is subject to the wear. After reaching the 170 000 km run, the tread surface of some wheels begins to crumble. There was a suspicion that the reason for crumb formation of the wheel surface may be insufficient or excessive wheel hardness or its chemical composition. In order to confirm or deny this suspicion the following studies were conducted: the examination of the rim surface, the study of the wheel metal hardness and the document analysis of the wheel production and their comparison with the results of wheel hardness measurement. Practical value. The technical condition of locomotives is one of the bases of safety and reliability of the rolling stock. The reduction of the wheel wear significantly reduces the operating costs of railway transport. After study completion it was found that there was no evidence to suggest that the ratio of the wheel-rail hardness could be the cause of the wheel surface crumbling.

  4. Wear monitoring of single point cutting tool using acoustic emission ...

    Indian Academy of Sciences (India)

    was carried out to study the wear monitoring in single point cutting tool using acoustic emission techniques. 2. Propagation of stress wave due to crater wear and flank wear. Figure 1 show the crater wear occurred on the rake face of the tool. This crater wear emits stress wave, which propagates as spherical wave front and ...

  5. Microtomography evaluation of dental tissue wear surface induced by in vitro simulated chewing cycles on human and composite teeth

    Directory of Open Access Journals (Sweden)

    Rossella Bedini


    Full Text Available In this study a 3D microtomography display of tooth surfaces after in vitro dental wear tests has been obtained. Natural teeth have been compared with prosthetic teeth, manufactured by three different polyceramic composite materials. The prosthetic dental element samples, similar to molars, have been placed in opposition to human teeth extracted by paradontology diseases. After microtomography analysis, samples have been subjected to in vitro fatigue test cycles by servo-hydraulic mechanical testing machine. After the fatigue test, each sample has been subjected again to microtomography analysis to obtain volumetric value changes and dental wear surface images. Wear surface images were obtained by 3D reconstruction software and volumetric value changes were measured by CT analyser software. The aim of this work has been to show the potential of microtomography technique to display very clear and reliable wear surface images. Microtomography analysis methods to evaluate volumetric value changes have been used to quantify dental tissue and composite material wear.

  6. Changes in the Eye Microbiota Associated with Contact Lens Wearing

    Directory of Open Access Journals (Sweden)

    Hakdong Shin


    Full Text Available Wearing contact lenses has been identified as a risk factor for the development of eye conditions such as giant papillary conjunctivitis and keratitis. We hypothesized that wearing contact lenses is associated with changes in the ocular microbiota. We compared the bacterial communities of the conjunctiva and skin under the eye from 58 subjects and analyzed samples from 20 subjects (9 lens wearers and 11 non-lens wearers taken at 3 time points using a 16S rRNA gene-based sequencing technique (V4 region; Illumina MiSeq. We found that using anesthetic eye drops before sampling decreases the detected ocular microbiota diversity. Compared to those from non-lens wearers, dry conjunctival swabs from lens wearers had more variable and skin-like bacterial community structures (UniFrac; P value = 3.0. The results indicate that wearing contact lenses alters the microbial structure of the ocular conjunctiva, making it more similar to that of the skin microbiota. Further research is needed to determine whether the microbiome structure provides less protection from ocular infections.

  7. Sliding wear resistance of iron aluminides

    Indian Academy of Sciences (India)


    ordered intermetallic alloy (Johnson et al 1990, 1994,. 1996; Maupin et al 1992, 1993; Tu and Liu 1997; Kim and Kim 1998). Maupin et al (1992, 1993) had shown that the Fe3Al alloy having DO3 structure possesses mar- ginally lower wear rate than those with B2 structure. The wear resistance of Fe3Al alloy was found to ...

  8. Effective tool wear estimation through multisensory information ...

    African Journals Online (AJOL)

    Effective tool wear estimation through multisensory information fusion using Artificial Neural Network. ... On-line tool wear monitoring plays a significant role in industrial automation for higher productivity and product quality. In addition, an intelligent system is required to make a timely decision for tool change in machining ...

  9. Truck tyre wear assessment and prediction

    NARCIS (Netherlands)

    Lupker, H.A.; Montanaro, F.; Donadio, D.; Gelosa, E.; Vis, M.A.


    Tyre wear is a complex phenomenon. It depends non-linearly on numerous parameters, like tyre compound and design, vehicle type and usage, road conditions and road surface characteristics, environmental conditions (e.g., temperature) and many others. Yet, tyre wear has many economic and ecological

  10. Asphalt wear and pollution transport

    Energy Technology Data Exchange (ETDEWEB)

    Lindgren, Asa [Division of Traffic Engineering, Lulea University of Technology Lulea (Sweden)


    Studded tires cause extensive wear of road surfaces during winter producing small particles. Besides transporting different adsorbed pollutants these particles also discharge metal ions by their own natural content. The major part (95%) of the asphalt is composed of stone fractions. The rest consists mainly of bitumen, which contains trace quantities of metals. Laboratory studies in this study have demonstrated different adsorbing properties of metal ions, as well as differences in adsorption when comparing stone materials. Two stone materials, a gabbro and a porphyry, have been tested for their adsorption properties concerning Pb, Cu, Zn and Cd. The gabbro showed better adsorption capacity than the porphyry. Gabbro has coarser grains, it is softer, and also has a higher content of most metals compared to the porphyry. In all tests lead and copper are more adsorbed than zinc and cadmium. All metal ions are released at about the same pH ({approx}4)

  11. Scuba diving induces nitric oxide synthesis and the expression of inflammatory and regulatory genes of the immune response in neutrophils. (United States)

    Sureda, Antoni; Batle, Juan M; Capó, Xavier; Martorell, Miquel; Córdova, Alfredo; Tur, Josep A; Pons, Antoni


    Scuba diving, characterized by hyperoxia and hyperbaria, could increase reactive oxygen species production which acts as signaling molecules to induce adaptation against oxidative stress. The aim was to study the effects of scuba diving immersion on neutrophil inflammatory response, the induction of oxidative damage, and the NO synthesis. Nine male divers performed a dive at 50 m depth for a total time of 35 min. Blood samples were obtained at rest before the dive, after the dive, and 3 h after the diving session. Markers of oxidative and nitrosative damage, nitrite, and the gene expression of genes related with the synthesis of nitric oxide and lipid mediators, cytokine synthesis, and inflammation were determined in neutrophils. The mRNA levels of genes related with the inflammatory and immune response of neutrophils, except TNF-α, myeloperoxidase, and toll-like receptor (TLR) 2, significantly increased after the recovery period respect to predive and postdive levels. NF-κB, IL-6, and TLR4 gene expression reported significant differences immediately after diving respect to the predive values. Protein nitrotyrosine levels significantly rose after diving and remained high during recovery, whereas no significant differences were reported in malondialdehyde. Neutrophil nitrite levels as indicative of inducible nitric oxide synthase (iNOS) activity progressively increased after diving and recovery. The iNOS protein levels maintained the basal values in all situations. Scuba diving which combines hyperoxia, hyperbaria, and acute exercise induces nitrosative damage with increased nitrotyrosine levels and an inflammatory response in neutrophils. Copyright © 2014 the American Physiological Society.

  12. The differentiation of common species in a coral-reef fish assemblage for recreational scuba diving. (United States)

    Chen, Tsen-Chien; Ho, Cheng-Tze; Jan, Rong-Quen


    Recreational scuba diving is a popular activity of the coral reef tourism industry. In practice, local diving centers recommend interesting sites to help visiting divers make their plans. Fish are among the major attractions, but they need to be listed with care because the temporal occurrence of a fish species is difficult to predict. To address this issue, we propose methods to categorize each fish species based on its long-term occurrence and likelihood of being seen. We assume that there are K categories of occurrence of a fish assemblage and propose two methods [an arithmetic-mean method (AM) and a geometric-mean method (GM)] to define the range of species in each category. Experiments based on long term datasets collected at three underwater stations (each having 51-53 surveys and totals of 262-284 fish species) on coral reefs in southern Taiwan showed that when K = 4 (rare, occasional, frequent and common categories), 11-14 species were concurrently assigned to the common category by AM for data sets based on surveys 10, 15, 20, 25, 30, 35, 40, 45, or 51-53 in contrast to the 18-26 species assigned as common by GM. If a similarity index of 0.7 (compared to the total pool of fish species) was the minimum threshold for diver satisfaction, then 20-25 surveys provide sufficient data for listing the common species at a given dive spot. Common fish species, are the most temporally stable, and thus are more appropriate for attracting divers. These can be effectively differentiated by either AM or GM with at least 25 surveys. We suggest regular updating of each fish's category through periodic surveys to assure the accuracy of information at a particular dive spot.

  13. The JCMT Gould Belt Survey: a first look at Southern Orion A with SCUBA-2 (United States)

    Mairs, S.; Johnstone, D.; Kirk, H.; Buckle, J.; Berry, D. S.; Broekhoven-Fiene, H.; Currie, M. J.; Fich, M.; Graves, S.; Hatchell, J.; Jenness, T.; Mottram, J. C.; Nutter, D.; Pattle, K.; Pineda, J. E.; Salji, C.; Di Francesco, J.; Hogerheijde, M. R.; Ward-Thompson, D.; Bastien, P.; Bresnahan, D.; Butner, H.; Chen, M.; Chrysostomou, A.; Coudé, S.; Davis, C. J.; Drabek-Maunder, E.; Duarte-Cabral, A.; Fiege, J.; Friberg, P.; Friesen, R.; Fuller, G. A.; Greaves, J.; Gregson, J.; Holland, W.; Joncas, G.; Kirk, J. M.; Knee, L. B. G.; Marsh, K.; Matthews, B. C.; Moriarty-Schieven, G.; Mowat, C.; Rawlings, J.; Richer, J.; Robertson, D.; Rosolowsky, E.; Rumble, D.; Sadavoy, S.; Thomas, H.; Tothill, N.; Viti, S.; White, G. J.; Wouterloot, J.; Yates, J.; Zhu, M.


    We present the JCMT Gould Belt Survey's first look results of the southern extent of the Orion A Molecular Cloud (δ ≤ -5:31:27.5). Employing a two-step structure identification process, we construct individual catalogues for large-scale regions of significant emission labelled as islands and smaller-scale subregions called fragments using the 850 μm continuum maps obtained using SCUBA-2. We calculate object masses, sizes, column densities, and concentrations. We discuss fragmentation in terms of a Jeans instability analysis and highlight interesting structures as candidates for follow-up studies. Furthermore, we associate the detected emission with young stellar objects (YSOs) identified by Spitzer and Herschel. We find that although the population of active star-forming regions contains a wide variety of sizes and morphologies, there is a strong positive correlation between the concentration of an emission region and its calculated Jeans instability. There are, however, a number of highly unstable subregions in dense areas of the map that show no evidence of star formation. We find that only ˜72 per cent of the YSOs defined as Class 0+I and flat-spectrum protostars coincide with dense 850 μm emission structures (column densities >3.7 × 1021 cm-2). The remaining 28 per cent of these objects, which are expected to be embedded in dust and gas, may be misclassified. Finally, we suggest that there is an evolution in the velocity dispersion of YSOs such that sources which are more evolved are associated with higher velocities.

  14. Properties of the Scuba-2 850 μm Sources in the XMM-LSS Field (United States)

    Seo, Hyunjong; Jeong, Woong-Seob; Kim, Seong Jin; Pyo, Jeonghyun; Kim, Min Gyu; Ko, Jongwan; Kim, Minjin; Kim, Sam


    We carry out the study of 850 μm sources in a part of the XMM-LSS field. The 850 μm imaging data were obtained by the SCUBA-2 on the James Clerk Maxwell Telescope(JCMT) for three days in July 2015 with an integration time of 6.1 hours, covering a circular area with a radius of 15'. We choose the central area up to a radius of 9.15 arcmin for the study, where the noise distribution is relatively uniform. The root mean square (rms) noise at the center is 2.7 mJy. We identify 17 sources with S/N > 3.5. Differential number count is estimated in flux range between 3.5 and 9.0 mJy after applying various corrections derived by imaging simulations, which is consistent with previous studies. For detailed study on the individual sources, we select three sources with more reliable measurements (S/N > 4.5), and construct their spectral energy distributions (SEDs) from optical to far-infrared band. Redshift distribution of the sources ranges from 0.36 to 3.28, and their physical parameters are extracted using MAGPHYS model, which yield infrared luminosity L_{IR}= 10^{11.3}-10^{13.4} L_{⊙}, star formation rate SFR = 10^{1.3}-10^{3.2} M_{⊙}yr^{-1} and dust temperature T_{D} = 30-53 K. We investigate the correlation between L_{IR} and T_{D}, which appears to be consistent with previous studies.}

  15. Complications caused by contact lens wearing. (United States)

    Beljan, Jasna; Beljan, Kristina; Beljan, Zdravko


    Complications in wearing contact lenses are very rare and caused by poor maintenance, over-extended wear and wearing of contact lenses in a polluted environment. Regular control by a professional person can efficiently reduce the number of complications. This paper describes the most common risks factors for complications, and complications of wearing contact lenses with the classification according to the anatomic parts of the eye: eyelids, tear film, limbus, corneal epithelium, corneal stroma and corneal endothelium. Every complication has been described by the characteristic signs and symptoms, etiology and pathology, as well as therapy and prognosis. The paper describes how to select adequate customers as contact lens users, with proper education in order to ensure minimal incidence of complications due to contact lens wear, thus attracting a lot of satisfied and healthy customers.

  16. Biologically Based Restorative Management of Tooth Wear

    Directory of Open Access Journals (Sweden)

    Martin G. D. Kelleher


    Full Text Available The prevalence and severity of tooth wear is increasing in industrialised nations. Yet, there is no high-level evidence to support or refute any therapeutic intervention. In the absence of such evidence, many currently prevailing management strategies for tooth wear may be failing in their duty of care to first and foremost improve the oral health of patients with this disease. This paper promotes biologically sound approaches to the management of tooth wear on the basis of current best evidence of the aetiology and clinical features of this disease. The relative risks and benefits of the varying approaches to managing tooth wear are discussed with reference to long-term follow-up studies. Using reference to ethical standards such as “The Daughter Test”, this paper presents case reports of patients with moderate-to-severe levels of tooth wear managed in line with these biologically sound principles.

  17. Two-body wear performance of dental colored zirconia after different surface treatments. (United States)

    Bai, Yunyang; Zhao, Jing; Si, Wenjie; Wang, Xinzhi


    Colored zirconia is widely used in dental clinical practice; however, data pertaining to its wear resistance after different surface treatments are sparse. The purpose of this in vitro study was to evaluate the 2-body wear resistance of dental colored zirconia after different glazing and polishing treatments. Standardized specimens were prepared from dental zirconia (internal and external staining and no staining) and subjected to different surface treatments. The stained zirconia and control ceramics were polished with a Robinson brush and polishing paste or polishing kits, while the nonstained zirconia was airborne-particle abraded and glazed. The specimens were then abraded against steatite antagonists using a pin-on-disk wear tester. The wear depth for the specimens was measured using confocal microscopy. Wear areas on the steatite antagonists were measured by using an optical microscope. Scanning electron microscopy (SEM) was used to evaluate the wear pattern of the zirconia specimens. All data were statistically analyzed with 1-way ANOVA and the Tamhane test for post hoc analysis (α=.05). The surfaces polished using the Robinson brush and paste showed no wear. The wear depth of the unglazed surfaces was 42.27 ±3.21 ∼84.15 ±2.57 μm and 87.75 ±9.36 and 91.76 ±13.58 μm for the glazed surfaces. The antagonist wear area was 1.79 ±0.21 ∼2.69 ±0.34 mm 2 (unglazed) and 3.34 ±0.29 ∼4.51 ±0.88 mm 2 (glazed). SEM revealed chipping fractures, and peeling cracks were observed on the glazed zirconia surfaces, indicating a combination of fatigue and abrasive wear. The results of this in vitro study suggest that highly polished zirconia shows the least wear, including antagonist wear. Furthermore, glazed zirconia can be significantly more abrasive than polished zirconia. The wear properties of internally and externally stained zirconia are similar. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All

  18. Can asthmatic subjects dive?

    Directory of Open Access Journals (Sweden)

    Yochai Adir


    Full Text Available Recreational diving with self-contained underwater breathing apparatus (scuba has grown in popularity. Asthma is a common disease with a similar prevalence in divers as in the general population. Due to theoretical concern about an increased risk for pulmonary barotrauma and decompression sickness in asthmatic divers, in the past the approach to asthmatic diver candidates was very conservative, with scuba disallowed. However, experience in the field and data in the current literature do not support this dogmatic approach. In this review the theoretical risk factors of diving with asthma, the epidemiological data and the recommended approach to the asthmatic diver candidate will be described.

  19. Dynamic SEM wear studies of tungsten carbide cermets. [friction and wear experiments (United States)

    Brainard, W. A.; Buckley, D. H.


    Dynamic friction and wear experiments were conducted in a scanning electron microscope. The wear behavior of pure tungsten carbide and composite with 6 and 15 weight percent cobalt binder was examined, and etching of the binder was done to selectively determine the role of the binder in the wear process. Dynamic experiments were conducted as the tungsten carbide (WC) and bonded WC cermet surfaces were transversed by a 50 micron radiused diamond stylus. These studies show that the predominant wear process in WC is fracture initiated by plastic deformation, and the wear of the etched cermets is similar to pure WC. The presence of the cobalt binder reduces both friction and wear. The cementing action of the cobalt reduces granular separation, and promotes a dense polished layer because of its low shear strength film-forming properties. The wear debris generated from unetched surface is approximately the same composition as the bulk.

  20. Model development of work roll wear in hot strip mill (United States)

    Liu, Ziying; Guan, Yingping; Wang, Fengqin


    This paper, based on the analysis of the main factors(specific roll force, mean roll surface temperature, irregular edge wear and contact arc length) affecting roll wear, designed a new work roll wear model, the test data shows that the model can more accurately reflect the work roll wear, can be on-line prediction of work roll wear. The roll wear curve, including constant wear and irregular edge wear, presents a box shape, and the reasons also are showed in this paper. The top roll wear and bottom roll wear in the same mill are inconsistent, and the reasons are also analysed in this paper. Results show that the construction of the work roll mathematical model accords with the general law of work roll wear and tear; it can more accurately forecast roll wear online.

  1. Adhesive Wear of Rollers in Vacuum (United States)

    Shaeef, Iqbal; Krantz, Timothy L.


    This work was done to support NASA's James Webb Space Telescope that is equipped with a Near Infrared Camera and Spectrograph and Micro Shutter Assembly (MSA). A MSA mechanism's qualification test in cryogenic vacuum at 30deg K for 96K cycles resulted in roller wear and formation of some debris. Lab tests in vacuum were conducted at NASA Glenn Research Center (GRC) to understand the wear of Ti6Al4V mated with 440F steel rollers. Misalignment angle was found to have the most significant effect on debris formation. At misalignment angle of 1.4deg, significant amount of wear debris were formed within 50,000 cycles. Very few wear particles were found for a zero misalignment angle, and the total wear was small even after 367,000 cycles. The mode of wear in all the tests was attributed to adhesion, which was clearly evident from video records as well as the plate-like amalgamated debris material from both rollers. The adhesive wear rate was found to be approximately proportional to the misalignment angle. The wear is a two-way phenomenon, and the mixing of both roller materials in wear debris was confirmed by x-ray fluorescence (XRF) and EDX spectra. While there was a net loss of mass from the steel rollers, XRF and energy dispersive x-ray (EDX) spectra showed peaks of Ti on steel rollers, and peaks of Fe on Ti rollers. These results are useful for designers in terms of maintaining appropriate tolerances to avoid misalignment of rolling elements and the resulting severe wear

  2. Delamination and adhesive wear behavior of alpha-tocopherol-stabilized irradiated ultrahigh-molecular-weight polyethylene. (United States)

    Wannomae, Keith K; Christensen, Steven D; Micheli, Brad R; Rowell, Shannon L; Schroeder, Dave W; Muratoglu, Orhun K


    Wear and delamination of conventional ultrahigh-molecular-weight polyethylene (UHMWPE) components used in total knee arthroplasty can compromise long-term performance. Radiation cross-linking and melt-annealing reduced wear and increased delamination resistance of UHMWPE. An alternative material is the alpha-tocopherol-stabilized irradiated UHMWPE (alphaTPE), with improved mechanical and fatigue properties vs irradiated and melted UHMWPE. We studied the wear and delamination resistance of alphaTPE and conventional UHMWPE (direct compression molded GUR 1050 and Himont 1900) under reciprocating unidirectional motion. Wear resistance was improved, and no delamination was observed in alphaTPE. Accelerated aging did not alter the wear and delamination behavior of alphaTPE. The GUR 1050 UHMWPE showed delamination and pitting when subjected to unidirectional reciprocating motion after accelerated aging. Himont 1900 UHMWPE showed no delamination when subjected to unidirectional reciprocating motion after accelerated aging. alpha-Tocopherol-stabilized irradiated UHMWPE is advanced for use in total knee arthroplasty due to its high resistance to wear, delamination, and oxidation. Copyright 2010 Elsevier Inc. All rights reserved.

  3. Surface Modification by Friction Stir Processing of Low-Carbon Steel: Microstructure Investigation and Wear Performance (United States)

    Sattari, Behnoosh; Shamanian, Morteza; Salimijazi, Farshid; Salehi, Mehdi


    A low-carbon steel sheet with a thickness of 5 mm was subjected to friction stir processing (FSP) by one to four different passes. The microstructures of different regions were characterized using the optical microscopy and electron backscatter diffraction. The Vickers micro-harness was measured at the distance of 200 μm below the processed surfaces. The influence of pass numbers (PNs) on wear resistance was studied in terms of coefficients of friction (CoFs), weight losses and wear rates. SEM topographies of the worn surfaces were also studied to evaluate the wear mechanisms. Microstructure observations showed that Widmänstatten ferrite plates were formed in stir zones (SZs) and heat affected zones. As PN increased, these grains were widened due to the increment of the carbon diffusivity and lengthened because of the high heat input and microstructure anisotropy. Besides, increasing the PN causes increasing of the hardness and wear resistance, simultaneously. Specifically, the wear rate in the SZ was reduced from 2.8 × 10-2 mm3 m-1 in base metal to 0.3 × 10-2 mm3 m-1 in sample which was subjected to 4 FSP passes. However, variation in PN had no considerable effect on CoFs. Oxidative wear mechanism was observed on the worn surface of the steel and the FSPed samples while more debris was formed by increasing the PNs.

  4. "Kicking Up Some Dust": An Experimental Investigation Relating Lunar Dust Erosive Wear to Solar Power Loss (United States)

    Mpagazehe, Jeremiah N.; Street, Kenneth W., Jr.; Delgado, Irebert R.; Higgs, C. Fred, III


    The exhaust from retrograde rockets fired by spacecraft landing on the Moon can accelerate lunar dust particles to high velocities. Information obtained from NASA's Apollo 12 mission confirmed that these high-speed dust particles can erode nearby structures. This erosive wear damage can affect the performance of optical components such as solar concentrators. Solar concentrators are objects which collect sunlight over large areas and focus the light into smaller areas for purposes such as heating and energy production. In this work, laboratory-scale solar concentrators were constructed and subjected to erosive wear by the JSC-1AF lunar dust simulant. The concentrators were focused on a photovoltaic cell and the degradation in electrical power due to the erosive wear was measured. It was observed that even moderate exposure to erosive wear from lunar dust simulant resulted in a 40 percent reduction in power production from the solar concentrators.

  5. Quantifying Cutting and Wearing Behaviors of TiN- and CrNCoated AISI 1070 Steel

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    Ahmet Cakan


    Full Text Available Hard coatings such as titanium nitride (TiN and chromium nitride (CrN are widely used in cutting and forming tools against wear and corrosion. In the present study, hard coating films were deposited onto AISI 1070 steels by a cathodic arc evaporation plating (CAVP technique. These samples were subjected to wear in a conventional lathe for investigating the tribological behaviour of coating structure, and prenitrided subsurface composition was characterized using scanning electron microscopy (SEM, line scan analyses and X-ray diffraction (XRD. The wear properties of TiN- and CrNcoated samples were determined using an on-line monitoring system. The results show that TiN-coated samples demonstrate higher wear resistance than CrN-coated samples.

  6. Do daily wear opaquely tinted hydrogel soft contact lenses affect contrast sensitivity function at one meter? (United States)

    Ozkagnici, Ahmet; Zengin, Nazmi; Kamiş, Omit; Gündüz, Kemal


    To investigate the effects of daily wear opaquely tinted hydrogel soft contact lenses on contrast sensitivity functions, as measured using the Pelli-Robson chart viewed at 1 meter. Contrast sensitivity was measured in 48 healthy individuals before and 6 hours after soft contact lens wear. Twenty-four subjects used clear soft contact lenses and 24 used tinted soft contact lenses. The contrast sensitivity scores were significantly decreased monocularly and binocularly (P = 0.000 and P = 0.002, respectively) in the colored contact lens group whereas there were no significant changes in the clear contact lens group (P = 0.317 and P = 0.317, respectively). Color-tinted contact lenses were associated with a reduction of contrast sensitivity function. Therefore, those who wear colored contact lenses should be informed about the possible consequences of tinted contact lens wearing.

  7. Peripheral refraction in myopic children wearing orthokeratology and gas-permeable lenses. (United States)

    Kang, Pauline; Swarbrick, Helen


    To investigate changes in peripheral refraction after orthokeratology (OK) and rigid gas-permeable (GP) lens wear in progressing myopic children and to compare these peripheral defocus changes with reported changes in adults wearing OK. Sixteen myopic children subjects were fitted with an OK lens in one eye for overnight wear and a GP lens in the other eye for daily wear. Central and peripheral refraction were measured at baseline and then after 3 mo of lens wear. At baseline, myopic children showed relative peripheral hyperopia compared with central refraction at and beyond 20° in the temporal visual field (VF) and 30° in the nasal VF. Three months of OK lens wear produced hyperopic shifts in refraction between 30° in the temporal VF and 20° in the nasal VF. Peripheral refraction was similar to center at all positions in the temporal VF while remaining significantly myopic at all locations in the nasal VF. No change in either central or peripheral refraction was found after 3 mo in the eye assigned for GP lens wear. OK significantly reduced myopia in the central 20° VF in myopic children, converting relative peripheral hyperopia measured at baseline to relative peripheral myopia. These changes in children are similar to changes reported in myopic adults wearing OK lenses. No change in either central or peripheral refraction was found after 3 mo of daily GP lens wear. OK lenses can be used to induce myopic defocus in the periphery in myopic children and may thus provide a potential mechanism for myopia control.

  8. Tear film inflammatory mediators during continuous wear of contact lenses and corneal refractive therapy. (United States)

    González-Pérez, Javier; Villa-Collar, César; Sobrino Moreiras, Tomás; Lema Gesto, Isabel; González-Méijome, José Manuel; Rodríguez-Ares, María Teresa; Parafita, Manuel


    To study changes in tear film inflammatory mediators following continuous wear of silicone-hydrogel lenses and corneal refractive therapy with reverse geometry contact lenses. A prospective, case-control study. Twenty-eight subjects had worn silicone-hydrogel lenses on a 30-night continuous wear basis. Thirty-two subjects had worn corneal refractive therapy lenses on an overnight basis. Thirty-two matched control subjects were also recruited. Tear samples were obtained 12 months after initial fitting and assayed using ELISA for cytokines (interleukin (IL)-6 and IL-8), matrix metalloproteinase 9 (MMP-9) and epidermal growth factor (EGF). EGF was significantly increased 12 months after both interventions. IL-6, IL-8 and MMP-9 were significantly increased only after corneal refractive therapy. The inflammatory response for the corneal refractive therapy patients was found to be associated with the degree of myopia corrected and the presence of corneal staining. Moreover, an increased level of MMP-9 and EGF was found to be associated with the presence of corneal-pigmented arc in the corneal refractive therapy group. This research showed long-term increased tear levels of inflammatory markers in subjects wearing corneal refractive therapy lenses when compared with continuous wear of silicone-hydrogel lenses or no lens wear.

  9. Use of microhardness as a simple means of estimating relative wear resistance of carbide thermal spray coatings: Part 2. wear resistance of cemented carbide coatings (United States)

    Factor, Michael; Roman, Itzhak


    A selection of WC-Co and Cr3C2-25%NiCr coatings produced by plasma spray and high velocity oxygen fuel (HVOF) deposition techniques were subjected to various wear tests designed to simulate abrasion, cavitation, sliding, and particle erosion type wear mechanisms. All of the coatings were at least 200 µm thick and were deposited onto stainless steel substrates. In Part 1 of this contribution, the microstructures of the coatings were characterized and their mechanical properties were assessed using microindentation procedures. In this second part of the article, the behavior of the coatings when subjected to the various wear tests is reported and the utility of microhardness testing as an indication of relative wear resistance is discussed. It is shown that correctly performed, appropriate microhardness measurements are a good indication of abrasion resistance and sliding wear resistance, and also correlate well with cavitation resistance in Cr3C2-NiCr. The measurements were less useful for predicting erosion resistance for both Cr3C2-NiCr and WC-Co, however, and for abrasion resistance when WC-Co was ground against SiC. Here the contribution of micromechanisms involving fracturing and brittle failure is greater than that indicated by the coating microhardness, which is essentially a measurement of resistance to plastic deformation under equilibrium conditions.

  10. Risk factors for contact lens bacterial contamination during continuous wear. (United States)

    Szczotka-Flynn, Loretta B; Bajaksouzian, Saralee; Jacobs, Michael R; Rimm, Alfred


    Microbial contamination of contact lenses is associated with corneal infection and inflammation. This study determined the microbiological, clinical, and demographic factors that are associated with bacterial contamination of a silicone hydrogel contact lens when worn for continuous wear (CW). Two hundred five healthy subjects were enrolled in the Longitudinal Analysis of Silicone Hydrogel Contact Lens Study and were fitted with lotrafilcon A lenses for monthly CW and followed for 1 year. Lenses were aseptically removed after 1 week and 4 months of wear and cultured using an agar sandwich technique. Lids and conjunctiva were routinely cultured at baseline and after 1 week and 4 months of CW. Lenses and ocular sites were considered to have substantial microbial bioburden when they harbored pathogenic organisms or high levels of commensal organisms. Univariate and multivariate logistic regression analyses were conducted to examine whether substantial conjunctival or lid bioburden, subject demographics, lens-wearing history, symptoms, and biomicroscopic signs were associated with lens bioburden. About one third (32.4%) of subjects had substantial bacterial bioburden in either eye across multiple visits. Over half (53.2%) and about one tenth (11.7%) of subjects had substantial lid and conjunctival bioburden, respectively, and 11.2% discontinued because of discomfort. The adjusted odds ratios (and 95% confidence intervals) for presence of substantial lens bioburden were 2.49 (1.17-5.30), 4.24 (1.45-12.40), and 4.11 (1.17-14.46) for substantial lid bioburden, substantial conjunctival bioburden, and lens discomfort, respectively. Bacterial contamination of silicone hydrogel contact lenses is common during CW. Substantial lens bioburden is associated with discomfort precluding successful CW. The presence of substantial lid and conjunctival bioburden is associated with a 2.5-fold and more than fourfold greater risk of substantial lens bioburden and is likely the major route

  11. Crystal Orientation Dependence of Gallium Nitride Wear. (United States)

    Zeng, Guosong; Sun, Wei; Song, Renbo; Tansu, Nelson; Krick, Brandon A


    We explore how crystallographic order and orientation affect the tribological (friction and wear) performance of gallium nitride (GaN), through experiments and theory. Friction and wear were measured in every direction on the c-plane of GaN through rotary wear experiment. This revealed a strong crystallographic orientation dependence of the sliding properties of GaN; a 60° periodicity of wear rate and friction coefficient was observed. The origin of this periodicity is rooted in the symmetry presented in wurtzite hexagonal lattice structure of III-nitrides. The lowest wear rate was found as 0.6 × 10 -7 mm 3 /Nm with , while the wear rate associated with had the highest wear rate of 1.4 × 10 -7 mm 3 /Nm. On the contrary, higher friction coefficient can be observed along while lower friction coefficient always appeared along . We developed a simple molecular statics approach to understand energy barriers associated with sliding and material removal; this calculated change of free energy associated with sliding revealed that there were smaller energy barriers sliding along as compared to the direction.

  12. Wear Characteristics of Metallic Biomaterials: A Review

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    Mohamed A. Hussein


    Full Text Available Metals are extensively used in a variety of applications in the medical field for internal support and biological tissue replacements, such as joint replacements, dental roots, orthopedic fixation, and stents. The metals and alloys that are primarily used in biomedical applications are stainless steels, Co alloys, and Ti alloys. The service period of a metallic biomaterial is determined by its abrasion and wear resistance. A reduction in the wear resistance of the implant results in the release of incompatible metal ions into the body that loosen the implant. In addition, several reactions may occur because of the deposition of wear debris in tissue. Therefore, developing biomaterials with high wear resistance is critical to ensuring a long life for the biomaterial. The aim of this work is to review the current state of knowledge of the wear of metallic biomaterials and how wear is affected by the material properties and conditions in terms of the type of alloys developed and fabrication processes. We also present a brief evaluation of various experimental test techniques and wear characterization techniques that are used to determine the tribological performance of metallic biomaterials.

  13. Epilepsy and recreational scuba diving: an absolute contraindication or can there be exceptions? A call for discussion. (United States)

    Almeida, Maria do Rosario G; Bell, Gail S; Sander, Josemir W


    Recreational scuba diving is a popular sport, and people with epilepsy often ask physicians whether they may engage in diving. Scuba diving is not, however, without risk for anyone; apart from the risk of drowning, the main physiological problems, caused by exposure to gases at depth, are decompression illness, oxygen toxicity, and nitrogen narcosis. In the United Kingdom, the Sport Diving Medical Committee advises that, to dive, someone with epilepsy must be seizure free and off medication for at least 5 years. The reasons for this are largely theoretical. We review the available evidence in the medical literature and diving websites. The risk of seizures recurring decreases with increasing time in remission, but the risk is never completely abolished. We suggest that people with epilepsy who wish to engage in diving, and the physicians who certify fitness to dive, should be provided with all the available evidence. Those who have been entirely seizure-free on stable antiepileptic drug therapy for at least 4 years, who are not taking sedative antiepileptic drugs and who are able to understand the risks, should then be able to consider diving to shallow depths, provided both they and their diving buddy have fully understood the risks.

  14. Message Collision Avoidance Protocols for Detecting Stray Nodes in a Scuba Diving Group Using Ultrasonic Multi-Hop Message Communication

    Directory of Open Access Journals (Sweden)

    Shinya Kaido


    Full Text Available Recent years have seen a growing interest in underwater communication and some progress has been made in this area. However, underwater communication is still immature compared with terrestrial communication. A prime reason for this is that the underwater environment is intrinsically not suitable for propagation of electric waves. Instead, ultrasonic waves are mainly used for underwater communication. Since ultrasonic waves cannot provide sufficient communication speed or capacity, they cannot use existing network technologies, which assume use of radio waves. In particular, communication in shallow water is still an uncharted territory. Few communication technologies are employed in environments where people enjoy scuba diving. This paper addresses problems faced by recreational scuba divers. It proposes constructing an ad hoc mesh-shaped network between divers within a group and use ultrasonic waves as transmission media in order to enable the detection of a stray diver. It also proposes a communication protocol in which messages are relayed in multiple hops, and a message collision avoidance method, which is intended to reduce the rate of packet loss caused by message propagation delay. We have implemented the proposed methods in a network simulator, and compared them with an existing communication method that has no message collision avoidance function, in terms of the packet loss rate, the stray driver detection rate, and the rate of the ability to communicate in multiple hops.

  15. Prediction of Wear in Crosslinked Polyethylene Unicompartmental Knee Arthroplasty

    Directory of Open Access Journals (Sweden)

    Jonathan Netter


    Full Text Available Wear-related complications remain a major issue after unicompartmental arthroplasty. We used a computational model to predict knee wear generated in vitro under diverse conditions. Inverse finite element analysis of 2 different total knee arthroplasty designs was used to determine wear factors of standard and highly crosslinked polyethylene by matching predicted wear rates to measured wear rates. The computed wear factor was used to predict wear in unicompartmental components. The articular surface design and kinematic conditions of the unicompartmental and tricompartmental designs were different. Predicted wear rate (1.77 mg/million cycles was very close to experimental wear rate (1.84 mg/million cycles after testing in an AMTI knee wear simulator. Finite element analysis can predict experimental wear and may reduce the cost and time of preclinical testing.

  16. Clinical and Wear Analyses of 9 Large Metal-on-Metal Total Hip Prostheses. (United States)

    Koper, M C; Mathijssen, N M C; Witt, F; Morlock, M M; Vehmeijer, S B W


    Metal-on-Metal (MoM) total hip arthroplasties (THA) are associated with pseudotumor formation and high revision rates. This prospective study analysed the clinical and wear analyses of 9 large Metal-on-Metal (MoM) total hip arthroplasties (THA) to understand the underlying mechanisms of failure. The MoM bearings were revised for multiple reasons; the main reason was pseudotumor formation. From 2006 till 2010 the Reinier de Graaf Hospital implanted 160 large head M2a-Magnum™ (Biomet Inc. Warsaw, Indiana, USA) THAs in 150 patients. The first year, 9 bearings were revised and analysed at the Biomechanics Section, Hamburg University of Technology, Germany. We performed clinical (Harris Hip Score, radiographic analysis, blood cobalt and chromium) and wear analysis (implant, tissue and fluid) of the 9 bearings. Since this study did not fall under the scope of the Medical Research Involving Human Subjects Act in The Netherlands, no ethical approval was necessary. In this prospective study all patient details were anonymized by the corresponding author, all other authors were blinded during the research and wear analyses. Patients with bilateral MoM implants were excluded. The 9 bearings had a median (IQR) survival of 41.0 (25) months in situ. From these bearings, three showed no noticeable wear. The median (IQR) head wear volume was 3.2 (3.6) mm3 and maximum wear depth 0.02 (0.02) mm. For the cup the median (IQR) wear volume was 0.23 (0.3) mm3 with a maximum wear depth of 0.03 (0.05) mm. An early identification of parameters related to failure of the MoM THA, such as pain, decreased range of motion, radiographic changes and high levels of blood cobalt and chromium is of great importance for patient's quality of life. Especially now patients and surgeons face the long term effects of all these bearings still in situ. This study reports the clinical and wear analyses of 9 MoM THA. In the majority of this group the reason for revision was pseudotumor formation. Most

  17. Multiscale Modeling of Wear Degradation in Cylinder Liners

    KAUST Repository

    Moraes, Alvaro


    Every mechanical system is naturally subjected to some kind of wear process that, at some point, will cause failure in the system if no monitoring or treatment process is applied. Since failures often lead to high economical costs, it is essential both to predict and to avoid them. To achieve this, a monitoring system of the wear level should be implemented to decrease the risk of failure. In this work, we take a first step into the development of a multiscale indirect inference methodology for state-dependent Markovian pure jump processes. This allows us to model the evolution of the wear level and to identify when the system reaches some critical level that triggers a maintenance response. Since the likelihood function of a discretely observed pure jump process does not have an expression that is simple enough for standard nonsampling optimization methods, we approximate this likelihood by expressions from upscaled models of the data. We use the Master Equation (ME) to assess the goodness-of-fit and to compute the distribution of the hitting time to the critical level.

  18. Predicting the Wear of High Friction Surfacing Aggregate

    Directory of Open Access Journals (Sweden)

    David Woodward


    Full Text Available High friction surfacing (HFS is a specialist type of road coating with very high skid resistance. It is used in the UK at locations where there is significant risk of serious or fatal accidents. This paper considers the aggregate used in HFS. Calcined bauxite is the only aggregate that provides the highest levels of skid resistance over the longest period. No naturally occurring aggregate has been found to give a comparable level of in-service performance. This paper reviews the historical development of HFS in the UK relating to aggregate. In-service performance is predicted in the laboratory using the Wear test which subjects test specimens to an estimated 5–8 years simulated trafficking. Examples are given of Wear test data. They illustrate why calcined bauxite performs better than natural aggregate. They show how the amount of calcined bauxite can be reduced by blending with high skid resistant natural aggregates. Data from the Wear test can be related to every HFS laboratory experiment and road trial carried out in the UK for over the last 50 years. Anyone considering the prediction of HFS performance needs to carefully consider the data given in this paper with any other test method currently being considered or used to investigate HFS.

  19. Effect of a single, open-sea, air scuba dive on human micro- and macrovascular function. (United States)

    Lambrechts, Kate; Pontier, Jean-Michel; Balestra, Costantino; Mazur, Aleksandra; Wang, Qiong; Buzzacott, Peter; Theron, Michael; Mansourati, Jacques; Guerrero, François


    Previous studies have shown that bubble formation induced endothelial damage on conduit arteries. We aim to evaluate the effect of diving on microvascular and macrovascular function. Nine divers took part in a SCUBA dive at 30 msw (400 kPa), for 30 min of bottom time. Pre- and post-dive, they underwent an assessment of endothelial-dependent (acetylcholine) and endothelial-independent (sodium nitroprusside) microvascular function (laser Doppler flowmetry), as well as endothelial-dependent (flow-mediated dilation) and endothelial-independent (nitroglycerin-mediated dilation) function. Bubble grades were monitored with Doppler according to the Spencer grade. The mean KISS bubble score ranged from 21.10 ± 4.7 at rest to 55.03 ± 8.8 after knee flexion. The increase in cutaneous vascular conductance elicited by either acetylcholine (25.34 ± 6.71 to 7.63 ± 1.25 %, p = 0.021) or sodium nitroprusside (35.24 ± 8.75 to 7.61 ± 1.86 %, p = 0.017) was significantly reduced after diving. Similarly, both flow-mediated dilation (10.8 ± 0.9 to 5.4 ± 1.5 %, p = 0.002) and nitroglycerin-mediated dilation (15 ± 1.1 to 6.5 ± 1.6 %, p = 0.002) were also significantly decreased. There were no correlations between vascular parameters and bubble formation. There appears to be a reduction in endothelium-dependent and endothelium-independent, macro- and microvascular function associated with diving. Our results suggest that in the process of vascular dysfunction during diving, functional changes in the vessel wall may not be limited to the endothelium and may be mediated by alterations in vascular smooth muscle.

  20. The measurement of enamel wear of two toothpastes. (United States)

    Joiner, Andrew; Weader, Elizabeth; Cox, Trevor F


    The aim of this study was to compare the enamel abrasivity of a whitening toothpaste with a standard silica toothpaste. Polished human enamel blocks (4 x 4 mm) were indented with a Knoop diamond. The enamel blocks were attached to the posterior buccal surfaces of full dentures and worn by adult volunteers for 24 hours per day. The blocks were brushed ex vivo for 30 seconds, twice per day with the randomly assigned toothpaste (n = 10 per treatment). The products used were either a whitening toothpaste containing Perlite or a standard silica toothpaste. After four, eight and twelve weeks, one block per subject was removed and the geometry of each Knoop indent was re-measured. From the baseline and post-treatment values of indent length, the amount of enamel wear was calculated from the change in the indent depth. The mean enamel wear (sd) for the whitening toothpaste and the standard silica toothpaste after four weeks was 0.20 (0.11) and 0.14 (0.10); after 8 weeks was 0.44 (0.33) and 0.18 (0.17), and after 12 weeks was 0.60 (0.72) and 0.67 (0.77) microns respectively. After four, eight and twelve weeks, the difference in enamel wear between the two toothpastes was not of statistical significance (p > 0.05, 2 sample t-test) at any time point. The whitening toothpaste did not give a statistically significantly greater level of enamel wear as compared to a standard silica toothpaste over a 4-, 8- and 12-weeks period.

  1. Risk factors for contact lens-induced papillary conjunctivitis associated with silicone hydrogel contact lens wear. (United States)

    Tagliaferri, Angela; Love, Thomas E; Szczotka-Flynn, Loretta B


    Contact lens-induced papillary conjunctivitis (CLPC) continues to be a major cause of dropout during extended wear of contact lenses. This retrospective study explores risk factors for the development of CLPC during extended wear of silicone hydrogel lenses. Data from 205 subjects enrolled in the Longitudinal Analysis of Silicone Hydrogel Contact Lens study wearing lotrafilcon A silicone hydrogel lenses for up to 30 days of continuous wear were used to determine risk factors for CLPC in this secondary analysis of the main cohort. The main covariates of interest included substantial lens-associated bacterial bioburden and topographically determined lens base curve-to-cornea fitting relationships. Additional covariates of interest included history of adverse events, time of year, race, education level, gender, and other subject demographics. Statistical analyses included univariate logistic regression to assess the impact of potential risk factors on the binary CLPC outcome and Cox proportional hazards regression to describe the impact of those factors on time-to-CLPC diagnosis. Across 12 months of follow-up, 52 subjects (25%) experienced CLPC. No associations were found between the CLPC development and the presence of bacterial bioburden, lens-to-cornea fitting relationships, history of adverse events, gender, or race. Contact lens-induced papillary conjunctivitis development followed the same seasonal trends as the local peaks in environmental allergens. Lens fit and biodeposits, in the form of lens-associated bacterial bioburden, were not associated with the development of CLPC during extended wear with lotrafilcon A silicone hydrogel lenses.

  2. The effects of daily wear contact lenses on goblet cell density. (United States)

    Connor, C G; Campbell, J B; Steel, S A; Burke, J H


    Some patients can wear contact lenses with a low tear breakup time while others with an identical tear breakup time cannot wear lenses. This suggests the current method of tear film assessment is inadequate at differentiating between these two types of patients. The study attempts to expand our knowledge of the tear film with special attention directed to a critical yet little studied component: mucin. Mucin is vital to maintenance of the tear film and functions as a tear film stabilizer. The condition of the precorneal tear film is a major determinant in the success of contact lens wear. Eighteen subjects free of ocular surface disease who had never worn contact lenses had the goblet cell density of their inferior bulbar conjunctiva determined by impression cytology. The subjects were then fit in a 38 percent water polymacon lens and their goblet cell density determined on a monthly basis for 6 months. Nearly a 2-fold increase in goblet cell density was observed in 88 percent of the subjects over the 6-month period. The first statistically significant increase occurred 5 months after the initiation of lens wear when the goblet cell density rose from 4.19-7.84 percent. We speculate the increase in goblet cells is an adaptive response of the ocular surface to a coated daily wear contact lens.

  3. How Chronic Fatigue Syndrome Wears Patients Out (United States)

    ... How Chronic Fatigue Syndrome Wears Patients Out Study suggests body amplifies fatigue ... what it's like for those who struggle with chronic fatigue syndrome, and researchers suggest in a new report that ...

  4. Wear and repair of stainless steel crowns

    National Research Council Canada - National Science Library

    Yilmaz, Y; Kara, N Belduz; Yilmaz, A; Sahin, H


    The purpose of this study was to determine the wear of stainless steel crowns (SSCs) in children, and compare the extent of microleakage in SSCs that had been repaired using either a cermet glass-ionomer cement...

  5. Implant wear mechanisms-basic approach

    Energy Technology Data Exchange (ETDEWEB)

    Bhatt, Himanshu; Goswami, Tarun [Department of Biomedical, Industrial and Human Factors Engineering, Wright State University, Dayton, OH 45435 (United States)


    Numerous parameters control the long-term performance of a total hip joint arthroplasty. The articulating motions between the femoral and the acetabular components produce wear debris in a hip implant. Surface roughness, clearance, coefficient of friction and sliding distance are found to be contributing parameters that affect wear rates. Wear produced in a hip implant leads to the loosening of a hip prosthesis and thus failure of the hip implant. Ultra-high-molecular-weight polyethylene (UHMWPE) has been successfully used as an acetabular weight bearing component in the THR applications. Cross-linked UHMWPE was found to improve the lifespan of an artificial hip. A gradient cross-linking of UHMWPE has been observed to be a recent development in implant bearing materials. During in vitro studies, gradient cross-linked UHMWPE showed nearly undetectable wear rates. (topical review)

  6. Mammalian dental function and wear: A review

    Directory of Open Access Journals (Sweden)

    Peter S. Ungar


    Full Text Available This paper presents a brief synopsis of work on relationships between mammalian tooth form and function, and considers the role of dental wear in studies of mammal teeth. Mammalian teeth function both as guides for chewing and as tools for initiating and propagating cracks through food items. They tend to vary in form and structure with the mechanical properties of foods a species has evolved to eat; and we can learn a lot about relationships between teeth and diet by comparing species. One area of special interest is tooth wear. Dental structure and chemistry combine in ways that lead wear to sculpt occlusal surfaces so a tooth can develop or maintain its functional efficiency. Dental wear, especially that on microscopic scales, can also serve as a proxy for diet in fossil species, as specific types of food leave distinctive patterns.

  7. Prediction of wear rates in comminution equipment

    DEFF Research Database (Denmark)

    Jensen, Lucas Roald Dörig; Fundal, Erling; Møller, Per


    Raw material comminution equipment may be exposed to excessive wear, which makes it difficult to operate minerals processing plants continuously because lengthy and unplanned shut-downs interrupt the overall process. In general, most comminution equipment is fine-tuned to operate at low vibrations...... and to achieve guaranteed performance. From an economical point of view, it is always preferred to replace all worn parts during the planned maintenance shutdowns. When operating comminution equipment, the wear rate receives little attention and is considered a secondary matter. However, experience shows......-resistant high chromium white cast iron (21988/JN/HBW555XCr21), a heat-treated wear resistant steel (Hardox 400) and a plain carbon construction steel (S235). Quartz, which accounts for the largest wear loss in the cement industry, was chosen as abrasive. Other process parameters such as velocity (1–7 m...

  8. The SCUBA-2 Cosmology Legacy Survey : The nature of bright submm galaxies from 2 deg2 of 850-μm imaging

    NARCIS (Netherlands)

    Michałowski, Michał J.; Dunlop, J. S.; Koprowski, M. P.; Cirasuolo, M.; Geach, J. E.; Bowler, R. A. A.; Mortlock, A.; Caputi, K. I.; Aretxaga, I.; Arumugam, V.; Chen, Chian-Chou; McLure, R. J.; Birkinshaw, M.; Bourne, N.; Farrah, D.; Ibar, E.; van der Werf, P.; Zemcov, M.


    We present physical properties [redshifts (z), star-formation rates (SFRs) and stellar masses (Mstar)] of nearly 2000 bright (S850 > 4 mJy) submm galaxies in the ~2 deg2 COSMOS and UDS fields selected with SCUBA-2 on the JCMT, representing the largest homogeneous sample of 850-um-selected sources to


    Energy Technology Data Exchange (ETDEWEB)

    Sadavoy, S. I.; Di Francesco, J.; Johnstone, D.; Fallscheer, C.; Matthews, B. [Department of Physics and Astronomy, University of Victoria, P.O. Box 355, STN CSC, Victoria, BC V8W 3P6 (Canada); Currie, M. J.; Jenness, T. [Joint Astronomy Centre, 660 N. A' ohoku Place, University Park, Hilo, HI 96720 (United States); Drabek, E.; Hatchell, J. [School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL (United Kingdom); Nutter, D. [School of Physics and Astronomy, Cardiff University, Queen' s Buildings, The Parade, Cardiff CF24 3AA (United Kingdom); Andre, Ph.; Hennemann, M.; Hill, T.; Koenyves, V. [Laboratoire AIM, CEA/DSM-CNRS-Universite Paris Diderot, IRFU/Service d' Astrophysique, Saclay, F-91191 Gif-sur-Yvette (France); Arzoumanian, D. [IAS, CNRS (UMR 8617), Universite Paris-Sud 11, Batiment 121, F-91400 Orsay (France); Benedettini, M. [Istituto di Astrofisica e Planetologia Spaziali, via Fosso del Cavaliere 100, I-00133 Rome (Italy); Bernard, J.-P. [CNRS, IRAP, 9 Av. colonel Roche, BP 44346, F-31028 Toulouse Cedex 4 (France); Duarte-Cabral, A. [Universite de Bordeaux, LAB, UMR 5804, F-33270 Floirac (France); Friesen, R. [Dunlap Institute, University of Toronto, Toronto, ON M5S 3H8 (Canada); Greaves, J. [School of Physics and Astronomy, University of St. Andrews, North Haugh, St. Andrews, Fife KY16 9SS (United Kingdom); Collaboration: JCMT and Herschel Gould Belt Survey teams; and others


    We present Herschel observations from the Herschel Gould Belt Survey and SCUBA-2 science verification observations from the JCMT Gould Belt Survey of the B1 clump in the Perseus molecular cloud. We determined the dust emissivity index using four different techniques to combine the Herschel PACS+SPIRE data at 160-500 {mu}m with the SCUBA-2 data at 450 {mu}m and 850 {mu}m. Of our four techniques, we found that the most robust method was filtering out the large-scale emission in the Herschel bands to match the spatial scales recovered by the SCUBA-2 reduction pipeline. Using this method, we find {beta} Almost-Equal-To 2 toward the filament region and moderately dense material and lower {beta} values ({beta} {approx}> 1.6) toward the dense protostellar cores, possibly due to dust grain growth. We find that {beta} and temperature are more robust with the inclusion of the SCUBA-2 data, improving estimates from Herschel data alone by factors of {approx}2 for {beta} and by {approx}40% for temperature. Furthermore, we find core mass differences of {approx}< 30% compared to Herschel-only estimates with an adopted {beta} = 2, highlighting the necessity of long-wavelength submillimeter data for deriving accurate masses of prestellar and protostellar cores.

  10. Effect of Wearing Socks, Stockings and Leather Shoe on Shoe Microclimate and Wear Comfort


    三ツ井, 紀子; Michiko, Mitsui


    The effects of socks, stockings and leather shoe on wear comfort and microclimate between shoe and skin while exercising has been studied by seven women under laboratory conditions. Temperature and absolute humidity in wearing socks or stockings were higher than barefooted. Further under wearing shoes and socks or stockings they are increased. Temperature and absolute humidity at the measuring point were the highest between the first and the second toes. Inside socks or stockings with shoes a...

  11. Accommodation in young adults wearing aspheric multifocal soft contact lenses (United States)

    Lindskoog Pettersson, Anna; Wahlberg Ramsay, Marika; Lundström, Linda; Rosén, Robert; Nilsson, Maria; Unsbo, Peter; Brautaset, Rune


    The aim of the present project was to investigate accommodative behavior in young adults and adolescents fitted with an aspheric multifocal (center distance) contact lens with focus on evaluating whether these lenses can be an alternative treatment for subjects in which a reduced level of blur and thereby accommodation in near vision is aimed at. Twenty normal subjects aged between 21 and 35 years participated in the study. Aberrometry was perfomed using a Zywave™ aberrometer, first on the uncorrected eyes of all subjects, and again while the subjects wore a multifocal contact lens with a +1.00 add. A Shin-Nippon N Vision-K 5001 Autoref-Keratometer was used to measure accommodative response with two different refractive corrections: (1) habitual spectacle correction only, and (2) habitual correction and a aspheric multifocal (center distance) contact lens. Four hours of adaptation to the lens was allowed. The lag when wearing only the habitual spectacles was compared with the lag while wearing both the habitual spectacles and the aspheric multifocal contact lens. The mean lag of accommodation for the subject group was 0.85 D (±0.57 SD) and 0.75 D (±0.52 SD) without and with the multifocal lens, respectively. Statistical analyses showed no difference in lag (t = 0.8479, p = 0.407) with and without the lens. In conclusion, young normal subjects do not relax accommodation when fitted with aspheric multifocal center distance lenses when the addition is +1.00. It is therefore unlikely that subjects with accommodative ability, in whom the treatment purpose is to reduce blur and thereby accommodation, can be effectively treated with such lenses.

  12. Third abrasive wear mode: is it possible?

    Directory of Open Access Journals (Sweden)

    Ronaldo Câmara Cozza


    Full Text Available The objective of this paper is to propose an initial discussion on the characterization of a third abrasive wear mode. The results obtained in a previous work [1] under different test conditions revealed the occurrence of the superposition of the “rolling” and “grooving” abrasive wear modes. This phenomenon was denoted “micro-rolling abrasion” due to the observation that “rolling abrasion” was found to act on “grooving abrasion”.

  13. [Study on friction and wear properties of dental zirconia ceramics processed by microwave and conventional sintering methods]. (United States)

    Guoxin, Hu; Ying, Yang; Yuemei, Jiang; Wenjing, Xia


    This study evaluated the wear of an antagonist and friction and wear properties of dental zirconia ceramic that was subjected to microwave and conventional sintering methods. Ten specimens were fabricated from Lava brand zirconia and randomly assigned to microwave and conventional sintering groups. A profile tester for surface roughness was used to measure roughness of the specimens. Wear test was performed, and steatite ceramic was used as antagonist. Friction coefficient curves were recorded, and wear volume were calculated. Finally, optical microscope was used to observe the surface morphology of zirconia and steatite ceramics. Field emission scanning electron microscopy was used to observe the microstructure of zirconia. Wear volumes of microwave and conventionally sintered zirconia were (6.940±1.382)×10⁻², (7.952±1.815) ×10⁻² mm³, respectively. Moreover, wear volumes of antagonist after sintering by the considered methods were (14.189±4.745)×10⁻², (15.813±3.481)×10⁻² mm³, correspondingly. Statistically significant difference was not observed in the wear resistance of zirconia and wear volume of steatite ceramic upon exposure to two kinds of sintering methods. Optical microscopy showed that ploughed surfaces were apparent in zirconia. The wear surface of steatite ceramic against had craze, accompanied by plough. Scanning electron microscopy showed that zirconia was sintered compactly when subjected to both conventional sintering and microwave methods, whereas grains of zirconia sintered by microwave alone were smaller and more uniform. Two kinds of sintering methods are successfully used to produce dental zirconia ceramics with similar friction and wear properties.

  14. Acanthamoeba keratitis and contact lens wear: static or increasing problem? (United States)

    Foulks, Gary N


    The occurrence of Acanthamoeba keratitis is increasing in the United States because of an expanding population at risk of infection and sporadic outbreaks of infection. Such outbreaks are the result of lapses in contact lens wear and care and of alterations in water quality and water treatment procedures. Although improved techniques in diagnosis are available, better identification of infection alone does not explain an increase in the observed occurrence of the disease. Likewise, there does not appear to be an increase in the virulence or infectivity of the amoebae. Strategies for prevention, including patient education, improved decontaminating agents, maintenance of water treatment standards, and possible immunization of subjects at risk, are needed.

  15. Contact lens wear and the development of squamous metaplasia of the surface cells of the conjunctiva. (United States)

    Doughty, Michael J


    To review the reported effects of contact lens wear on the surface epithelial cells of the human conjunctiva as assessed by conjunctival impression cytology (CIC). A literature search was undertaken to identify reports on the conjunctival health after contact lens wear, principally as assessed using CIC. Of 26 reports identified, 22 examined the bulbar conjunctiva, and 2 examined the tarsal conjunctiva. Just 16 reports provided data from which mean squamous metaplasia grades could be calculated, with the overall grade being just 0.7 on a 0 to 3 scale. Only 13 of these studies provided unambiguous data on the duration of contact lens wear, and only an apparent trend was evident in that grades of squamous metaplasia increased over early years of lens wear. Such a trend was not statistically significant either up to 6 years of average lens wear (P>0.05) or over all studies (P>0.5). The estimated variability in squamous metaplasia was substantially greater when low grades were reported, an observation that either reflects the heterogeneity in the cell response or highlights the difficulty in assigning low grades to cell samples. Based on subjective grading, CIC studies reveal no clearly definable relationship between the duration of contact lens wear and the extent of development of conjunctival squamous metaplasia. Logically, therefore, objective methods to assess squamous metaplasia are needed. Various options for quantitative CIC are discussed, including the use of in vivo confocal microscopy.

  16. Three-dimensional in vitro measurements of tooth wear using fluoridated dentifrices. (United States)

    Al-Mashhadani, A; Plygkos, I; Bozec, L; Rodriguez, J M


    The aim of this study was to compare differences in wear of human enamel and dentine in vitro using a 3D measurement method comparing silica versus non-silica containing fluoridated dentifrices (Colgate Total(™) [CT] or Fluor Protector Gel(™) [FPG]). Mounted native enamel (n = 36) and polished dentine (n = 36) samples were subjected to 10 wear cycles. Each cycle consisted of: (1) 1 hour remineralization in artificial saliva (AS); (2) 10 minute erosion (0.3% citric acid; pH = 2.8); (3) 2 minute toothbrush abrasion in AS (G1, control) or a slurry of 3:1 by weight of AS:dentifrice (G2 = CT; G3 = FPG) under a load of 2 N. Each group contained 12 enamel and 12 dentine samples. Paired pre- and post-wear scans made with a contacting scanner were digitally superimposed using ball bearings as datum. Mean and (SD) enamel wear was G1 = 21.9 μm (6.4); G2 = 15.2 μm (2.8); G3 = 16.9 μm (3.2). Enamel wear was not different between dentifrices (p = 0.99). Both dentifrices resulted in less enamel wear compared to the control (p Dental Association.

  17. Pseudomembranous candidiasis in patient wearing full denture

    Directory of Open Access Journals (Sweden)

    Nurdiana Nurdiana


    Full Text Available Background: Oral candidiasis is a common opportunistic infection of the oral cavity caused by an overgrowth of Candida species, the commonest being Candida albicans. Candida albicans is a harmless commensal organism inhabiting the mouths but it can change into pathogen and invade tissue and cause acute and chronic disease. Dentures predispose to infection with Candida in as many as 65% of elderly people wearing full upper dentures. Purpose: The purpose of this case report is to discuss thrush in patient wearing full denture which rapidly developed. Case: This paper report a case of 57 year-old man who came to the Oral Medicine Clinic Faculty of Dentistry Airlangga University with clinical appearance of pseudomembranous candidiasis (thrush. Case Management: Diagnosis of this case is confirmed with microbiology examination. Patient was wearing full upper dentures, and from anamnesis known that patient wearing denture for 24 hours and he had poor oral hygiene. Patient was treated with topical (nystatin oral suspension and miconazole oral gel and systemic (ketoconazole antifungal. Patient also instructed not to wear his denture and cleaned white pseudomembrane on his mouth with soft toothbrush. Conclusion: Denture, habit of wearing denture for 24 hours, and poor oral hygiene are predisposing factors of thrush and it can healed completely after treated with topical and systemic antifungal.

  18. Development and Performance Evaluation of an Abrasive Wear ...

    African Journals Online (AJOL)

    The wear of tillage tools is a major source of economic constraints to local farmers. Estimating wear in the field is time consuming and expensive. Abrasive wear testing machines developed in advanced countries are not available in Ghana. This makes the study of wear related problems at laboratory levels difficult in the ...

  19. Detection and Monitoring of Wear Using Imaging Methods

    NARCIS (Netherlands)

    Zhang, Jindang


    Wear is traditionally measured offline. A new methodology for online detection and monitoring of wear has been investigated in this thesis. This methodology consists of design of an online wear testing apparatus and development of techniques for online wear detection and monitoring using imaging

  20. SCUBA-2 Ultra Deep Imaging EAO Survey (STUDIES): Faint-end Counts at 450 μm (United States)

    Wang, Wei-Hao; Lin, Wei-Ching; Lim, Chen-Fatt; Smail, Ian; Chapman, Scott C.; Zheng, Xian Zhong; Shim, Hyunjin; Kodama, Tadayuki; Almaini, Omar; Ao, Yiping; Blain, Andrew W.; Bourne, Nathan; Bunker, Andrew J.; Chang, Yu-Yen; Chao, Dani C.-Y.; Chen, Chian-Chou; Clements, David L.; Conselice, Christopher J.; Cowley, William I.; Dannerbauer, Helmut; Dunlop, James S.; Geach, James E.; Goto, Tomotsugu; Jiang, Linhua; Ivison, Rob J.; Jeong, Woong-Seob; Kohno, Kotaro; Kong, Xu; Lee, Chien-Hsu; Lee, Hyung Mok; Lee, Minju; Michałowski, Michał J.; Oteo, Iván; Sawicki, Marcin; Scott, Douglas; Shu, Xin Wen; Simpson, James M.; Tee, Wei-Leong; Toba, Yoshiki; Valiante, Elisabetta; Wang, Jun-Xian; Wang, Ran; Wardlow, Julie L.


    The SCUBA-2 Ultra Deep Imaging EAO Survey (STUDIES) is a three-year JCMT Large Program aiming to reach the 450 μm confusion limit in the COSMOS-CANDELS region to study a representative sample of the high-redshift far-infrared galaxy population that gives rise to the bulk of the far-infrared background. We present the first-year data from STUDIES. We reached a 450 μm noise level of 0.91 mJy for point sources at the map center, covered an area of 151 arcmin2, and detected 98 and 141 sources at 4.0σ and 3.5σ, respectively. Our derived counts are best constrained in the 3.5-25 mJy regime using directly detected sources. Below the detection limits, our fluctuation analysis further constrains the slope of the counts down to 1 mJy. The resulting counts at 1-25 mJy are consistent with a power law having a slope of -2.59 (±0.10 for 3.5-25 mJy, and {}-0.7+0.4 for 1-3.5 mJy). There is no evidence of a faint-end termination or turnover of the counts in this flux density range. Our counts are also consistent with previous SCUBA-2 blank-field and lensing-cluster surveys. The integrated surface brightness from our counts down to 1 mJy is 90.0 ± 17.2 Jy deg-2, which can account for up to {83}-16+15 % of the COBE 450 μm background. We show that Herschel counts at 350 and 500 μm are significantly higher than our 450 μm counts, likely caused by its large beam and source clustering. High angular resolution instruments like SCUBA-2 at 450 μm are therefore highly beneficial for measuring the luminosity and spatial density of high-redshift dusty galaxies.

  1. The SCUBA-2 cosmology legacy survey: Ultraluminous star-forming galaxies in a z = 1.6 cluster

    Energy Technology Data Exchange (ETDEWEB)

    Smail, Ian; Swinbank, A. M.; Danielson, A. L. R.; Edge, A. C.; Simpson, J. M. [Institute for Computational Cosmology, Durham University, South Road, Durham DH1 3LE (United Kingdom); Geach, J. E. [Centre for Astrophysics Research, Science and Technology Research Institute, University of Hertfordshire, Hatfield AL10 9AB (United Kingdom); Tadaki, K. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo (Japan); Arumugam, V.; Dunlop, J. S.; Ivison, R. J. [Institute for Astronomy, Royal Observatory, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Hartley, W. [Institute for Astronomy, ETH Zurich, Wolfgang-Pauli-Strasse 27, CH-8093 Zurich (Switzerland); Almaini, O.; Conselice, C. [School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG9 2RD (United Kingdom); Bremer, M. N. [H. H. Wills Physics Laboratory, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Chapin, E. [XMM SOC, ESAC, Apartado 78, E-28691 Villanueva de la Canada, Madrid (Spain); Chapman, S. C. [Department of Physics and Atmospheric Science, Dalhousie University, 6310 Coburg Road, Halifax, Nova Scotia B3H 4R2 (Canada); Scott, D. [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada); Simpson, C. J. [Astrophysics Research Institute, Liverpool John Moores University, Liverpool Science Park, 146 Brownlow Hill, Liverpool L3 5RF (United Kingdom); Karim, A. [Argelander-Institute of Astronomy, Bonn University, Auf dem Hügel 71, D-53121, Bonn (Germany); Kodama, T. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); and others


    We analyze new SCUBA-2 submillimeter and archival SPIRE far-infrared imaging of a z = 1.62 cluster, Cl 0218.3–0510, which lies in the UKIRT Infrared Deep Sky Survey/Ultra-Deep Survey field of the SCUBA-2 Cosmology Legacy Survey. Combining these tracers of obscured star-formation activity with the extensive photometric and spectroscopic information available for this field, we identify 31 far-infrared/submillimeter-detected probable cluster members with bolometric luminosities ≳10{sup 12} L {sub ☉} and show that by virtue of their dust content and activity, these represent some of the reddest and brightest galaxies in this structure. We exploit ALMA submillimeter continuum observations, which cover one of these sources, to confirm the identification of a SCUBA-2-detected ultraluminous star-forming galaxy in this structure. Integrating the total star-formation activity in the central region of the structure, we estimate that it is an order of magnitude higher (in a mass-normalized sense) than clusters at z ∼ 0.5-1. However, we also find that the most active cluster members do not reside in the densest regions of the structure, which instead host a population of passive and massive, red galaxies. We suggest that while the passive and active populations have comparable near-infrared luminosities at z = 1.6, M{sub H} ∼ –23, the subsequent stronger fading of the more active galaxies means that they will evolve into passive systems at the present day that are less luminous than the descendants of those galaxies that were already passive at z ∼ 1.6 (M{sub H} ∼ –20.5 and M{sub H} ∼ –21.5, respectively, at z ∼ 0). We conclude that the massive galaxy population in the dense cores of present-day clusters were already in place at z = 1.6 and that in Cl 0218.3–0510 we are seeing continuing infall of less extreme, but still ultraluminous, star-forming galaxies onto a pre-existing structure.

  2. Wear-resistance of Aluminum Matrix Microcomposite Materials

    Directory of Open Access Journals (Sweden)

    M. Kandeva


    Full Text Available A procedure is developed for the study of wear of aluminum alloys AlSi7 obtained by casting, reinforced by TiC microparticles, before and after heat treatment. Tribological study is realized under conditions of friction on counterbody with fixed abrasive. Experimental results were obtained for mass wear, wear rate, wear intensity and wear-resistance of the alloys with different wt% of microparticles.

  3. Effect of wearing fingers rings on the behavioral and psychological symptoms of dementia: An exploratory study. (United States)

    Yokoi, Teruo; Okamura, Hitoshi; Yamamoto, Tomoka; Watanabe, Katsuya; Yokoi, Shigeko; Atae, Hitoshi; Ueda, Masayuki; Kuwayama, Takahiro; Sakamoto, Shigekazu; Tomino, Saaya; Fujii, Hideo; Honda, Takefumi; Morita, Takayosi; Yukawa, Takafumi; Harada, Nobuko


    This study was conducted to examine the effects of an approach that wears finger rings on elderly females with behavioral and psychological symptoms of dementia. The subjects were seven Japanese dementia patients living in elderly nursing homes. A single-case experimental design was adopted for the study. Each study subject was asked to put rings on her finger (from 9:00 to 19:00) for 7 days. The Neuropsychiatric Inventory, scenes of behavioral and psychological symptoms of dementia, interest in wearing rings, self-awareness, and overall profile were determined to assess the effect on the patients of wearing rings. The majority of nursing care providers stated, based on their assessment, that the "irritability/lability" that was noted during the baseline period disappeared during the ring-wearing intervention period in the three patients who displayed an interest in rings. In the assessment of the self-awareness ability, these three women were aware themselves of their intellect collapsing and were capable of conjecturing their own and others' minds. It was commonly seen that the nursing staff, even though they had not been asked to do so by the researchers, told the patients, "Mrs. XX, you look so beautiful" when they found a patient wearing rings. Individuals with low self-esteem are inclined to get angry and display aggression. In subjects with low self-esteem, anger and aggression readily arise when they are slighted by others. Self-esteem is low in those women who are aware of their own status of collapsing intellect. It is concluded that the words of conjuration, "you look so beautiful," which the wearing of the ring per se by the patient elicited from the caregivers heightened the self-esteem and alleviated "irritability/lability" in the study subjects.

  4. The Long-Term Effects of Silicone Hydrogel Contact Lens Wear on Corneal Morphology

    Directory of Open Access Journals (Sweden)

    Yelda Yıldız


    Full Text Available Pur po se: To evaluate the effects of silicone hydrogel contact lenses (SHCL on central corneal thickness (CCT, corneal endothelial cell morphology, and tear functions. Ma te ri al and Met hod: Fifty-five eyes of 28 SHCL wearers (Group 1 and 52 eyes of 26 healthy subjects (Group 2 were included in this study’. According to their contact lens wearing time, the contact lens wearing subjects were divided into 2 groups: Group 1a - wearing time less than 1 year and Group 1b - wearing time more than 1 year. CCT, epithelial thickness, corneal endothelial cell morphology, ocular surface disease index score (OSDI, and tear break-up time (TBUT were evaluated. Re sults: In Group 1 and Group 2, the mean CCT was 561.85±39.98 µm and 537.25±27.12 µm, respectively (p: 0.001.The epithelial thickness was 50.38±5.41 µm and 55.64±5.32 µm, respectively (p: 0.001. In Group 1a and Group1 b, the mean CCT was 573.39±33.86 µm and 546.96±42.98 µm (p: 0.014 and the epithelial thickness was 49.51±4.78 µm and 51.50±6.04 µm (p>0.05, respectively. In Group 1, the percentage of endothelial cells larger than 700µ was low, while the percentage of endothelial cells between 200 and 400µ was high (p<0,05. Dis cus si on: With SHCL wear, the corneal morphology is more affected in the short-term period. During long-term contact lens wear, the cornea enters an adaptation period and shows near-normal morphology. Tear functions are not affected by short- or long-term SHCL wear. (Turk J Ophthalmol 2012; 42: 91-6

  5. An approach to understanding tribological behaviour of dental composites through volumetric wear loss and wear mechanism determination; beyond material ranking. (United States)

    Altaie, Asmaa; Bubb, Nigel L; Franklin, Paul; Dowling, Adam H; Fleming, Garry J P; Wood, David J


    To investigate the fundamental wear mechanisms of six resin-based composite (RBC) formulations during short-term in vitro wear testing. RBC materials were condensed into rectangular bar-shaped specimens and light irradiated using the ISO 4049 specimen manufacture and irradiation protocol. Wear testing (n=10 specimens for each RBC) was performed on a modified pin-on-plate wear test apparatus and wear facets were analysed for wear volume loss using a white light profilometer. The wear tested RBC specimens and their corresponding antagonists were analysed using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), respectively to determine the wear mechanism. Data generated using the profilometer showed variations in the mean total wear volume (mm(3)) between the RBCs tested (psystem rather than relying on a simple wear ranking for the RBC materials as is routinely the case in dental research studies. Copyright © 2017 Elsevier Ltd. All rights reserved.


    Energy Technology Data Exchange (ETDEWEB)

    Ron Matthews


    This Final Technical Report discusses the progress was made on the experimental and numerical tasks over the duration of this project regarding a new technique for decreasing engine friction and wear via liner rotation. The experimental subtasks involved quantifying the reduction in engine friction for a prototype rotating liner engine relative to a comparable baseline engine. Both engine were single cylinder conversions of nominally identical production four-cylinder engines. Hot motoring tests were conducted initially and revealed that liner rotation decreased engine friction by 20% under motoring conditions. A well-established model was used to estimate that liner rotation should decrease the friction of a four-cylinder engine by 40% under hot motoring conditions. Hot motoring tear-down tests revealed that the crankshaft and valve train frictional losses were essentially the same for the two engines, as expected. However, the rotating liner engine had much lower (>70%) piston assembly friction compared to the conventional engine. Finally, we used the Instantaneous IMEP method to compare the crank-angle resolved piston assembly friction for the two engines. Under hot motoring conditions, these measurements revealed a significant reduction in piston assembly friction, especially in the vicinity of compression TDC when the lubrication regime transitions from hydrodynamic through mixed and into boundary friction. We have some remaining problems with these measurements that we expect to solve during the next few weeks. We will then perform these measurements under firing conditions. We also proposed to improve the state-of-the-art of numerical modeling of piston assembly friction for conventional engines and then to extend this model to rotating liner engines. Our research team first modeled a single ring in the Purdue ring-liner test rig. Our model showed good agreement with the test rig data for a range of speeds and loads. We then modeled a complete piston

  7. Influence of Shot Peening on Abrasion Wear in Real Conditions of Ni-Cu-Ausferritic Ductile Iron

    Directory of Open Access Journals (Sweden)

    Wieczorek A. N.


    Full Text Available The paper presents results of the wear tests of chain wheels made of austempered ductile iron with various content of residual austenite. The aim of this study was to demonstrate the impact of the dynamic surface treatment (shot peening on wear properties of surface layers of the chain wheels tested that were subjected to the action of quartz abrasive. Apart from determining the value of the abrasive wear, examinations of the magnetic phase content in the microstructure were carried out and plots of hardness of the surface layer as a function of the distance from the surface and microstructure of the materials were prepared. Based on the results, the following was found: an increase in the abrasive wear and a reduction in the hardness of the surface layer of chain wheels subjected to shot peening, as well as reduction of susceptibility to negative action of the shot for cast irons with the structure of upper ausferrite.

  8. Effect of deep cryogenic treatment on the microstructure and wear performance of Cr-Mn-Cu white cast iron grinding media (United States)

    Vidyarthi, M. K.; Ghose, A. K.; Chakrabarty, I.


    The phase transformation and grinding wear behavior of Cr-Mn-Cu white cast irons subjected to destabilization treatment followed by air cooling or deep cryogenic treatment were studied as a part of the development program of substitute alloys for existing costly wear resistant alloys. The microstructural evolution during heat treatment and the consequent improvement in grinding wear performance were evaluated with optical and scanning electron microscopy, X-ray diffraction analysis, bulk hardness, impact toughness and corrosion rate measurements, laboratory ball mill grinding wear test etc. The deep cryogenic treatment has a significant effect in minimizing the retained austenite content and converts it to martensite embedded with fine M7C3 alloy carbides. The cumulative wear losses in cryotreated alloys are lesser than those with conventionally destabilized alloys followed by air cooling both in wet and dry grinding conditions. The cryotreated Cr-Mn-Cu irons exhibit comparable wear performance to high chromium irons.

  9. Virtopsy-postmortem multislice computed tomography (MSCT) and magnetic resonance imaging (MRI) in a fatal scuba diving incident. (United States)

    Plattner, Thomas; Thali, Michael J; Yen, Kathrin; Sonnenschein, Martin; Stoupis, Christoforos; Vock, Peter; Zwygart-Brügger, Karin; Kilchör, Thomas; Dirnhofer, Richard


    The body of a 44-year-old scuba diver was examined using postmortem multislice computed tomography (MSCT) and magnetic resonance imaging (MRI), and findings were verified by subsequent autopsy. The goal was to find out whether the important pathomorphological findings for the reconstruction of events and the identification of cause and manner of death could be identified using modem digital cross-sectioning techniques. The findings of a massive vital decompression with pulmonary barotrauma and lethal gas embolism were identified in the radiological images. MSCT and MRI were superior to autopsy in the demonstration of the extent and distribution of gas accumulation in intraparenchymal blood vessels of internal organs as well as in areas of the body inaccessible by standard autopsy.

  10. 2D speckle tracking echocardiography of the right ventricle free wall in SCUBA divers after single open sea dive. (United States)

    Susilovic-Grabovac, Zora; Obad, Ante; Duplančić, Darko; Banić, Ivana; Brusoni, Denise; Agostoni, Piergiuseppe; Vuković, Ivica; Dujic, Zeljko; Bakovic, Darija


    The presence of circulating gas bubbles and their influence on pulmonary and right heart hemodynamics was reported after uncomplicated self-contained underwater breathing apparatus (SCUBA) dive(s). Improvements in cardiac imaging have recently focused great attention on the right ventricle (RV). The aim of our study was to evaluate possible effects of a single air SCUBA dive on RV function using 2D speckle tracking echocardiography in healthy divers after single open sea dive to 18 meters of seawater, followed by bottom stay of 47 minutes with a direct ascent to the surface. Twelve experienced male divers (age 39.5 ± 10.5 years) participated in the study. Echocardiographic assessment of the right ventricular function (free wall 2 D strain, tricuspid annular planes systolic excursion [TAPSE], lateral tricuspid annular peak systolic velocity [RV s`] and fractional area change [FAC]) was performed directly prior to and 30, 60, 90 and 120 minutes after surfacing. Two-dimensional strain of all three segments of free right ventricular wall showed a significant increase in longitudinal shortening in post-dive period for maximally 26% (basal), 15.4% (mid) and 16.3% (apical) as well as TAPSE (11.6%), RV FAC (19.2%), RV S` (12.7%) suggesting a rise in systolic function of right heart. Mean pulmonary arterial pressure (mean PAP) increased post-dive from 13.3 mmHg to maximally 23.5 mmHg (P = .002), indicating increased RV afterload. Our results demonstrated that single dive with significant bubble load lead to increase in systolic function and longitudinal strain of the right heart in parallel with increase in mean PAP. © 2017 John Wiley & Sons Australia, Ltd.

  11. The SCUBA-2 850 μm Follow-up of WISE-selected, Luminous Dust-obscured Quasars (United States)

    Fan, Lulu; Jones, Suzy F.; Han, Yunkun; Knudsen, Kirsten K.


    Hot dust-obscured galaxies (Hot DOGs) are a new population recently discovered in the Wide-field Infrared Survey Explorer All-Sky survey. Multiwavelength follow-up observations suggest that they are luminous, dust-obscured quasars at high redshift. Here we present the JCMT SCUBA-2 850 μm follow-up observations of 10 Hot DOGs. Four out of ten Hot DOGs have been detected at >3σ level. Based on the IR SED decomposition approach, we derive the IR luminosities of AGN torus and cold dust components. Hot DOGs in our sample are extremely luminous with most of them having {L}{IR}{tot}> {10}14 {L}⊙ . The torus emissions dominate the total IR energy output. However, the cold dust contribution is still non-negligible, with the fraction of the cold dust contribution to the total IR luminosity (˜8%-24%) being dependent on the choice of torus model. The derived cold dust temperatures in Hot DOGs are comparable to those in UV bright quasars with similar IR luminosity, but much higher than those in SMGs. Higher dust temperatures in Hot DOGs may be due to the more intense radiation field caused by intense starburst and obscured AGN activities. Fourteen and five submillimeter serendipitous sources in the 10 SCUBA-2 fields around Hot DOGs have been detected at >3σ and >3.5σ levels, respectively. By estimating their cumulative number counts, we confirm the previous argument that Hot DOGs lie in dense environments. Our results support the scenario in which Hot DOGs are luminous, dust-obscured quasars lying in dense environments, and being in the transition phase between extreme starburst and UV-bright quasars.

  12. The JCMT Gould Belt Survey: the effect of molecular contamination in SCUBA-2 observations of Orion A (United States)

    Coudé, S.; Bastien, P.; Kirk, H.; Johnstone, D.; Drabek-Maunder, E.; Graves, S.; Hatchell, J.; Chapin, E. L.; Gibb, A. G.; Matthews, B.; JCMT Gould Belt Survey Team


    Thermal emission from cold dust grains in giant molecular clouds can be used to probe the physical properties, such as density, temperature and emissivity in star-forming regions. We present the Submillimetre Common-User Bolometer Array (SCUBA-2) shared-risk observations at 450 and 850 μm of the Orion A molecular cloud complex taken at the James Clerk Maxwell Telescope (JCMT). Previous studies showed that molecular emission lines can contribute significantly to the measured fluxes in those continuum bands. We use the Heterodyne Array Receiver Programme 12CO J = 3-2 integrated intensity map for Orion A in order to evaluate the molecular line contamination and its effects on the SCUBA-2 maps. With the corrected fluxes, we have obtained a new spectral index α map for the thermal emission of dust in the well-known integral-shaped filament. Furthermore, we compare a sample of 33 sources, selected over the Orion A molecular cloud complex for their high 12CO J = 3-2 line contamination, to 27 previously identified clumps in OMC 4. This allows us to quantify the effect of line contamination on the ratio of 850-450 μm flux densities and how it modifies the deduced spectral index of emissivity β for the dust grains. We also show that at least one Spitzer-identified protostellar core in OMC 5 has a 12CO J = 3-2 contamination level of 16 per cent. Furthermore, we find the strongest contamination level (44 per cent) towards a young star with disc near OMC 2. This work is part of the JCMT Gould Belt Legacy Survey.

  13. The JCMT Gould Belt Survey: A First Look at SCUBA-2 Observations of the Lupus I Molecular Cloud (United States)

    Mowat, C.; Hatchell, J.; Rumble, D.; Kirk, H.; Buckle, J.; Berry, D. S.; Broekhoven-Fiene, H.; Currie, M. J.; Jenness, T.; Johnstone, D.; Mottram, J. C.; Pattle, K.; Tisi, S.; Di Francesco, J.; Hogerheijde, M. R.; Ward-Thompson, D.; Bastien, P.; Bresnahan, D.; Butner, H.; Chen, M.; Chrysostomou, A.; Coudé, S.; Davis, C. J.; Drabek-Maunder, E.; Duarte-Cabral, A.; Fich, M.; Fiege, J.; Friberg, P.; Friesen, R.; Fuller, G. A.; Graves, S.; Greaves, J.; Holland, W.; Joncas, G.; Kirk, J. M.; Knee, L. B. G.; Mairs, S.; Marsh, K.; Matthews, B. C.; Moriarty-Schieven, G.; Rawlings, J.; Retter, B.; Richer, J.; Robertson, D.; Rosolowsky, E.; Sadavoy, S.; Thomas, H.; Tothill, N.; Viti, S.; White, G. J.; Wouterloot, J.; Yates, J.; Zhu, M.


    This paper presents observations of the Lupus I molecular cloud at 450 and 850 μm with Submillimetre Common User Bolometer Array (SCUBA-2) as part of the James Clerk Maxwell Telescope Gould Belt Survey (JCMT GBS). Nine compact sources, assumed to be the discs of young stellar objects (YSOs), 12 extended protostellar, pre-stellar and starless cores, and one isolated, low-luminosity protostar, are detected in the region. Spectral energy distributions, including submillimetre fluxes, are produced for 15 YSOs, and each is fitted with the models of Robitaille et al. The proportion of Class 0/I protostars is higher than that seen in other Gould Belt regions such as Ophiuchus and Serpens. Circumstellar disc masses are calculated for more evolved sources, while protostellar envelope masses are calculated for protostars. Up to four very low luminosity objects are found; a large fraction when compared to other Spitzer c2d regions. One YSO has a disc mass greater than the minimum mass solar nebula. 12 starless/protostellar cores are detected by SCUBA-2 and their masses are calculated. The stability of these cores is examined using both the thermal Jeans mass and a turbulent virial mass when possible. Two cores in Lupus I are super-Jeans and contain no known YSOs. One of these cores has a virial parameter of 1.1 ± 0.4, and could therefore be pre-stellar. The high ratio of Class 0/I to Class III YSOs (1:1), and the presence of a pre-stellar core candidate, provides support for the hypothesis that a shock recently triggered star formation in Lupus I.


    Energy Technology Data Exchange (ETDEWEB)

    Blau, Peter Julian [ORNL


    The work summarized here comprises the concluding effort of a multi-year project, funded by the U.S. Department of Energy, Office of Vehicle Technologies. It supports the development of a better understanding of advanced diesel engine designs in which enhanced power density, energy efficiency, and emissions control place increasing demands upon the durability of engine materials. Many kinds of metallic alloys are used in engines depending on the operating stresses, temperatures, and chemical environments. Exhaust valves, for example, are subjected to high temperatures and repetitive surface contacts that place demands on durability and frictional characteristics of the materials. Valves must continue to seal the combustion chamber properly for thousands of hours of cyclic engine operation and under varying operating conditions. It was the focus of this effort to understand the wear processes in the valve-seat area and to develop a model for the surface deformation and wear of that important interface. An annotated bibliography is provided to illustrate efforts to understand valve wear and to investigate the factors of engine operation that affect its severity and physical manifestation. The project for which this modeling effort was the final task, involved construction of a high-temperature repetitive impact test system as well as basic tribology studies of the combined processes of mechanical wear plus oxidation at elevated temperatures. Several publications resulted from this work, and are cited in this report. The materials selected for the experimental work were high-performance alloys based on nickel and cobalt. In some cases, engine-tested exhaust valves were made available for wear analysis and to ensure that the modes of surface damage produced in experiments were simulative of service. New, production-grade exhaust valves were also used to prepare test specimens for experimental work along with the other alloy samples. Wear analysis of valves and seats

  15. Incisor wear and age in Yellowstone bison (United States)

    Christianson, D.A.; Gogan, P.J.P.; Podruzny, K.M.; Olexa, E.M.


    Biologists commonly use tooth eruption and wear patterns or cementum annuli techniques to estimate age of ungulates. However, in some situations the accuracy or sampling procedures of either approach are undesirable. We investigated the progression of several quantitative measures of wear with age, using permanent first incisors from Yellowstone bison (Bison bison), and tested for differences between sexes and herds. We further investigated the relationship of wear and age to explore an age-estimation method. Labial-lingual width (LLW) correlated best with assigned age (r2=0.66, males; r2=0.76 females). Labial-lingual width differed between sexes, with females showing ∼0.2 mm more wear than males. Additionally, differences in rate of wear existed between bison of the northern and central Yellowstone herds (1.2 and 0.9 mm/year, respectively). We developed a regression formula to test the power of LLW as an estimator of Yellowstone bison age. Our method provided estimated ages within 1 year of the assigned age 73% and 82% of the time for female and male bison, respectively.

  16. Investigation on wear characteristic of biopolymer gear (United States)

    Ghazali, Wafiuddin Bin Md; Daing Idris, Daing Mohamad Nafiz Bin; Sofian, Azizul Helmi Bin; Basrawi, Mohamad Firdaus bin; Khalil Ibrahim, Thamir


    Polymer is widely used in many mechanical components such as gear. With the world going to a more green and sustainable environment, polymers which are bio based are being recognized as a replacement for conventional polymers based on fossil fuel. The use of biopolymer in mechanical components especially gear have not been fully explored yet. This research focuses on biopolymer for spur gear and whether the conventional method to investigate wear characteristic is applicable. The spur gears are produced by injection moulding and tested on several speeds using a custom test equipment. The wear formation such as tooth fracture, tooth deformation, debris and weight loss was observed on the biopolymer spur gear. It was noted that the biopolymer gear wear mechanism was similar with other type of polymer spur gears. It also undergoes stages of wear which are; running in, linear and rapid. It can be said that the wear mechanism of biopolymer spur gear is comparable to fossil fuel based polymer spur gear, thus it can be considered to replace polymer gears in suitable applications.

  17. Dental Wear: A Scanning Electron Microscope Study

    Directory of Open Access Journals (Sweden)

    Luca Levrini


    Full Text Available Dental wear can be differentiated into different types on the basis of morphological and etiological factors. The present research was carried out on twelve extracted human teeth with dental wear (three teeth showing each type of wear: erosion, attrition, abrasion, and abfraction studied by scanning electron microscopy (SEM. The study aimed, through analysis of the macro- and micromorphological features of the lesions (considering the enamel, dentin, enamel prisms, dentinal tubules, and pulp, to clarify the different clinical and diagnostic presentations of dental wear and their possible significance. Our results, which confirm current knowledge, provide a complete overview of the distinctive morphology of each lesion type. It is important to identify the type of dental wear lesion in order to recognize the contributing etiological factors and, consequently, identify other more complex, nondental disorders (such as gastroesophageal reflux, eating disorders. It is clear that each type of lesion has a specific morphology and mechanism, and further clinical studies are needed to clarify the etiological processes, particularly those underlying the onset of abfraction.

  18. Randomized Trial of the Effect of Contact Lens Wear on Self-Perception in Children

    NARCIS (Netherlands)

    Walline, J.J.; Jones, L.A.; Sinnott, L.; Chitkara, M.; Coffey, B.; Jackson, J.M.; Manny, R.E.; Rath, M.J.; Prinstein, M.J.


    Purpose. To determine whether contact lens wear affects children's self-perceptions. Methods. The Adolescent and Child Health Initiative to Encourage Vision Empowerment Study was a randomized, single-masked trial conducted at five clinical centers in the United States. Subjects were 8- to

  19. Pattern of outsole shoe heel wear in infantry recruits. (United States)

    Finestone, Aharon S; Petrov, Kaloyan; Agar, Gabriel; Honig, Assaf; Tamir, Eran; Milgrom, Charles


    Excessive shoe heel abrasion is of concern to patients, parents and shoe manufacturers, but little scientific information is available. The purpose of this study was to describe the phenomenon in a group of infantry recruits performing similar physical activity, and search for biomechanical factors that might be related. Seventy-six subjects (median age 19) enrolled. Pre-training parameters measured included height, weight, tibial length, foot arch height and foot progression angle. Digital plantar pressure maps were taken to calculate arch indexes. Shoe heel abrasion was assessed manually after 14 weeks of training with different-sized clock transparencies and a calliper. Outsole abrasion was posterolateral, averaging 12 degrees on each shoe. The average heel volume that was eroded was almost 5 cm3. The angle of maximum wear was related to right foot progression angle (r = 0.27, p = 0.02). Recruits with lateral ankle sprains had higher angles of maximal abrasion (17° versus 10°, p = 0.26) and recruits with lateral heel abrasion had more lateral ankle sprains (14% versus 3%, p = 0.12). While shoe heel wear affects many people, very little has been done to measure it. In this study in healthy subjects, we found the main abrasion to be posterolateral. This seems to be related to foot progression angle. It was not related to hindfoot valgus/varus or other factors related to subtalar joint motion. These findings do not warrant modification of subtalar joint motion in order to limit shoe heel abrasion.

  20. The interactions between attrition, abrasion and erosion in tooth wear. (United States)

    Shellis, R Peter; Addy, Martin


    Tooth wear is the result of three processes: abrasion (wear produced by interaction between teeth and other materials), attrition (wear through tooth-tooth contact) and erosion (dissolution of hard tissue by acidic substances). A further process (abfraction) might potentiate wear by abrasion and/or erosion. Knowledge of these tooth wear processes and their interactions is reviewed. Both clinical and experimental observations show that individual wear mechanisms rarely act alone but interact with each other. The most important interaction is the potentiation of abrasion by erosive damage to the dental hard tissues. This interaction seems to be the major factor in occlusal and cervical wear. The available evidence is insufficient to establish whether abfraction is an important contributor to tooth wear in vivo. Saliva can modulate erosive/abrasive tooth wear, especially through formation of pellicle, but cannot prevent it. © 2014 S. Karger AG, Basel.

  1. Temperature effect on IG-11 graphite wear performance

    Energy Technology Data Exchange (ETDEWEB)

    Luo Xiaowei [Institute of Nuclear Energy and New Energy Technology, Tsinghua University, Beijing 100084 (China)]. E-mail:; Yu Suyuan [Institute of Nuclear Energy and New Energy Technology, Tsinghua University, Beijing 100084 (China); Sheng Xuanyu [Institute of Nuclear Energy and New Energy Technology, Tsinghua University, Beijing 100084 (China); He Shuyan [Institute of Nuclear Energy and New Energy Technology, Tsinghua University, Beijing 100084 (China)


    IG-11 graphite, used in the 10 MW high temperature gas-cooled test reactor (HTR-10), was tested under different temperatures on an SRV standard wear performance tester. The experiment temperatures were room temperature, 100, 200, 300 and 400 deg C. According to the reactor structure, the experiments were designed to test graphite-graphite and graphite-stainless steel wear. The wear debris was collected, and the worn surfaces and debris were observed under scanning electronic microscope (SEM). It was found that there were different wear mechanisms at different temperatures. The main wear mechanism at room temperature was abrasive wear; at 200 deg C, it was fatigue wear; at 400 deg C, adhesive wear was observed. This difference was mainly due to the change of stress distribution at the contact area. The distribution of wear debris was also analyzed by EDX particle analysis software.

  2. Quantitative wear particle analysis for osteoarthritis assessment. (United States)

    Guo, Meizhai; Lord, Megan S; Peng, Zhongxiao


    Osteoarthritis is a degenerative joint disease that affects millions of people worldwide. The aims of this study were (1) to quantitatively characterise the boundary and surface features of wear particles present in the synovial fluid of patients, (2) to select key numerical parameters that describe distinctive particle features and enable osteoarthritis assessment and (3) to develop a model to assess osteoarthritis conditions using comprehensive wear debris information. Discriminant analysis was used to statistically group particles based on differences in their numerical parameters. The analysis methods agreed with the clinical osteoarthritis grades in 63%, 50% and 61% of particles for no osteoarthritis, mild osteoarthritis and severe osteoarthritis, respectively. This study has revealed particle features specific to different osteoarthritis grades and provided further understanding of the cartilage degradation process through wear particle analysis - the technique that has the potential to be developed as an objective and minimally invasive method for osteoarthritis diagnosis.

  3. Friction and Wear Processes – Thermodynamic Approach

    Directory of Open Access Journals (Sweden)

    M. Banjac


    Full Text Available Tribology, as the scientific and professional discipline within the mechanical engineering, studies phenomena and processes on the interacting surfaces, in direct and indirect contact and in relative motion. It includes the study and application of the principles of friction, wear and lubrication, as well as phenomena connected with these processes. Given that a process involving friction is always accompanied by transformation of energy, more precisely an energy dissipation process which generates entropy, the concept of thermodynamic entropy production analysis represents one of appropriate tools for studying and analysing the behaviour of complex friction and wear processes. This paper presents a review of published works in which the thermodynamic approach was used in analysing the friction and wear processes in tribosystems.

  4. Adhesion and wear resistance of materials (United States)

    Buckley, D. H.


    Recent studies into the nature of bonding at the interface between two solids in contact or a solid and deposited film have provided a better understanding of those properties important to the adhesive wear resistance of materials. Analytical and experimental progress are reviewed. For simple metal systems the adhesive bond forces are related to electronic wave function overlap. With metals in contact with nonmetals, molecular-orbital energy, and density of states, respectively can provide insight into adhesion and wear. Experimental results are presented which correlate adhesive forces measured between solids and the electronic surface structures. Orientation, surface reconstruction, surface segregation, adsorption are all shown to influence adhesive interfacial strength. The interrelationship between adhesion and the wear of the various materials as well as the life of coatings applied to substrates are discussed. Metallic systems addressed include simple metals and alloys and these materials in contact with themselves, both oxide and nonoxide ceramics, diamond, polymers, and inorganic coating compounds, h as diamondlike carbon.

  5. Wear Resistant Amorphous and Nanocomposite Coatings

    Energy Technology Data Exchange (ETDEWEB)

    Racek, O


    Glass forming materials (critical cooling rate <10{sup 4}K.s{sup -1}) are promising for their high corrosion and wear resistance. During rapid cooling, the materials form an amorphous structure that transforms to nanocrystalline during a process of devitrification. High hardness (HV 1690) can be achieved through a controlled crystallization. Thermal spray process has been used to apply coatings, which preserves the amorphous/nanocomposite structure due to a high cooling rate of the feedstock particles during the impact on a substrate. Wear properties have been studied with respect to process conditions and feedstock material properties. Application specific properties such as sliding wear resistance have been correlated with laboratory tests based on instrumented indentation and scratch tests.

  6. Surface engineering for enhanced performance against wear

    CERN Document Server


    Surface Engineering constitutes a variety of processes and sub processes. Each chapter of this work covers specific processes by experts working in the area. Included for each topic are tribological performances for each process as well as results of recent research. The reader also will benefit from in-depth studies of diffusion coatings, nanocomposite films for wear resistance, surfaces for biotribological applications, thin-film wear, tribology of thermal sprayed coatings, hardfacing, plating for tribology and high energy beam surface modifications. Material scientists as well as engineers working with surface engineering for tribology will be particularly interested in this work.

  7. Wear Analysis of Wind Turbine Gearbox Bearings

    Energy Technology Data Exchange (ETDEWEB)

    Blau, Peter Julian [ORNL; Walker, Larry R [ORNL; Xu, Hanbing [ORNL; Parten, Randy J [ORNL; Qu, Jun [ORNL; Geer, Tom [ORNL


    The objective of this effort was to investigate and characterize the nature of surface damage and wear to wind turbine gearbox bearings returned from service in the field. Bearings were supplied for examination by S. Butterfield and J. Johnson of the National Wind Technology Center (NREL), Boulder, Colorado. Studies consisted of visual examination, optical and electron microscopy, dimensional measurements of wear-induced macro-scale and micro-scale features, measurements of macro- and micro-scale hardness, 3D imaging of surface damage, studies of elemental distributions on fracture surfaces, and examinations of polished cross-sections of surfaces under various etched and non-etched conditions.

  8. The effect of microstructure on abrasive wear of steel (United States)

    Kešner, A.; Chotëborský, R.; Linda, M.


    Abrasive wear of agricultural tools is one of the biggest problems in currently being. The amount of abrasive wear, depending on the microstructure, has been investigated in this work. Steels 25CrMo4 and 51CrV4 were used in this work to determine the effect of the microstructure on the abrasive wear. These steels are commonly used for components that have to withstand abrasive wear.SEM analysis was used to detect the microstructure. The standardized ASTM G65 method was used to compare the abrasive wear of steels. The results show that the abrasive wear depends on the microstructure of steels.

  9. Validation of a miniature thermochron for monitoring thoracolumbosacral orthosis wear time. (United States)

    Benish, Brian M; Smith, Kristin J; Schwartz, Michael H


    Prospective validation study. To establish the accuracy of miniature thermochrons for estimating thoracolumbosacral orthosis (TLSO) wear time in patients with adolescent idiopathic scoliosis. There has been an emphasis in recent years on measuring wear time as opposed to using subjective methods such as relying on the patient or parent estimation. By measuring the amount of time that was spent in the orthosis, uncertainty is reduced and the validity of the research is improved. Several types of devices have been employed for direct monitoring of orthosis wear time including strap tension monitors, pressure sensors, and temperature-time sensors (thermochrons). Direct monitoring studies have shown that relying on patient or parent report is inaccurate; the patient/parent report is clearly biased towards overestimation of wear time. Three miniature thermochrons (DS1922L iButton, Maxim Integrated Products, Inc., Sunnyvale, CA) were mounted underneath padding in the TLSOs of 7 participants diagnosed with adolescent idiopathic scoliosis. The participants wore their TLSO for 1 month. During this time, participants kept meticulous records of wear time in diaries. An algorithm was developed to automatically detect donning/doffing of the orthosis, and the results of the data reduction algorithm were compared with the diary (gold standard). Total wear time accuracy was 98.5% (0.37 hours/day), while the precise timing of donning/doffing was 92% accurate. An inexpensive, commercially available miniature thermochron and a simple robust algorithm can estimate TLSO wear time to a high degree of accuracy. This method is suitable for large-scale prospective studies examining the efficacy of bracing in adolescent idiopathic scoliosis, which remains a topic of controversy.

  10. Comparative in vitro wear resistance of CAD/CAM composite resin and ceramic materials. (United States)

    Zhi, Li; Bortolotto, Tissiana; Krejci, Ivo


    Composite resin is a promising option in computer-aided design and computer-aided manufacturing (CAD/CAM) dentistry; however, the wear resistance of composite resin remains a primary concern. The purpose of this in vitro study was to evaluate the wear resistance of 5 CAD/CAM materials (n=10), consisting of 4 composite resins (3M Lava Ultimate, Kerr experimental composite resin material, Vita Enamic, 3M Paradigm MZ100) and 1 ceramic (Vita Mark II) in contact with natural human enamel cusps. Specimens were loaded into a computer-controlled mastication simulator and subjected to 200000 mechanical cycles (49 N) against natural human enamel simultaneously with 500 thermal cycles (5°C to 50°C to 5°C). The wear resistance was analyzed by measuring the vertical substance loss (the maximum depth of the worn area) in the contact point area of the specimen. The worn surfaces were observed by scanning electron microscopy to determine the wear patterns. Vita Mark II exhibited the best wear resistance among the tested materials, followed by 3M Lava Ultimate, Vita Enamic, and 3M Paradigm MZ100. The Kerr experimental material exhibited the lowest wear resistance, yet its results were not significantly different from those of the 3 other composite resin blocks (P>.05). Within the limitations of this in vitro study, the wear resistance of composite resin blocks in contact with enamel cusps was significantly lower than that of a ceramic block. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  11. Effects of Load and Speed on Wear Rate of Abrasive Wear for 2014 Al Alloy (United States)

    Odabas, D.


    In this paper, the effects of the normal load and sliding speed on wear rate of two-body abrasive wear for 2014 Al Alloy were investigated in detail. In order to understand the variation in wear behaviour with load and speed, wear tests were carried out at a sliding distance of 11 m, a speed of 0.36 m/s, a duration of 30 s and loads in the range 3-11 N using 220 grit abrasive paper, and at a speed range 0.09-0.90 m/s, a load of 5 N and an average sliding distance of 11 m using abrasive papers of 150 grit size under dry friction conditions. Before the wear tests, solution treatment of the 2014 Al alloy was carried out at temperatures of 505 and 520 °C for 1 h in a muffle furnace and then quenched in cold water at 15 °C. Later, the ageing treatment was carried out at 185 °C for 8 h in the furnace. Generally, wear rate due to time increased linearly and linear wear resistance decreased with increasing loads. However, the wear rate was directly proportional to the load up to a critical load of 7 N. After this load, the slope of the curves decreased because the excessive deformation of the worn surface and the instability of the abrasive grains began to increase. When the load on an abrasive grain reaches a critical value, the groove width is about 0.17 of the abrasive grain diameter, and the abrasive grains begin to fail. The wear rate due to time increased slightly as the sliding speed increased in the range 0.09-0.90 m/s. The reason for this is that changes arising from strain rate and friction heating are expected with increasing sliding speeds.

  12. Simulation and experiment of the effect of clearance of impeller wear-rings on the performance of centrifugal pump (United States)

    Chen, S. X.; Pan, Z. Y.; Wu, Y. L.; Zhang, D. Q.


    The effect of clearance of impeller wear-rings on the performance of a centrifugal pump was investigated numerically and experimentally. The whole flow field model including front and back shrouds of pump was designed so as to accurately calculate the head and efficiency of the centrifugal pump. Based on RNG k-ε turbulence model, three wear-rings schemes were established, and the effects of clearance of impeller wear-rings on the hydraulic efficiency and mechanical efficiency of the centrifugal pump was analyzed, chiefly from the turbulent kinetic energy, vorticity and radial force angles. According to the results, it can be drawn that the head and total efficiency of the centrifugal pump increase as the clearance value of wear-rings narrows. The following reasons may account for it: firstly, as the clearance value of wear-rings declines, the turbulent kinetic energy and energy dissipation decrease within the impeller, and the impact of secondary flow at the inlet of impeller on the mainstream weakens slowly, which leads to a lower hydraulic loss, thus a higher hydraulic efficiency; secondly, radial force decreases with the clearance value of wear-rings, so the eccentric whirl of centrifugal pump is dampened, which results in a lower mechanical loss and a higher mechanical efficiency; thirdly, the front shroud leakage diminishes with the clearance value of wear-rings, therefore, the volume loss is reduced and volume efficiency improved. Finally, the first wear-ring scheme of impeller is adopted after comprehensive comparison of these three wear-ring schemes, because its efficiency is highest and it satisfies the requirements of the engineering application.

  13. Wear resistance analysis of the aluminum 7075 alloy and the nanostructured aluminum 7075 - silver nanoparticles composites

    Directory of Open Access Journals (Sweden)

    Estrada-Ruiz R.H.


    Full Text Available Nanostructured composites of the aluminum 7075 alloy and carbon-coated silver nanoparticles were synthetized by the mechanical milling technique using a high-energy mill SPEX 8000M; the powders generated were compacted, sintered and hot-extruded to produce 1 cm-diameter bars. The composites were then subjected to a wear test using a pin-on-disc device to validate the hypothesis that second phase-ductile nanometric particles homogenously distributed throughout the metalmatrix improve the wear resistance of the material. It was found that silver nanoparticles prevent the wear of the material by acting as an obstacle to dislocations movement during the plastic deformation of the contact surface, as well as a solid lubricant when these are separated from the metal-matrix.

  14. Wear and corrosion performances of new friction materials for automotive industry

    Directory of Open Access Journals (Sweden)

    R. Samur


    Full Text Available In this study, after a NiCr bond layer was deposited on a pearlitic, grey cast iron rotor disc of the kind used in a production passenger car (Toyota Corolla 1600 cc, Cr3C2-NiCr and Al2O3-TiO2powders were sprayed using High Velocity Oxygen Fuel(HVOF and plasma spray processes, respectively. The discs were subjected to cosmetic corrosion test according to SAE J2334 test standard. Additionally, wear tests were carried out using a reciprocating wear tester by rubbing a 10 mm diameter Al2O3 ball on the specimens machined from rotor discs in salt solution. It was found that the Cr3C2-NiCr coating (HSCN sprayed using HVOF method exhibited highest hardness and highest corrosion and wear resistances.

  15. Refractive behavior changes with six months daily wear of high and low oxygen permeability hydrogel contact lenses

    Directory of Open Access Journals (Sweden)

    W.D.H. Gillan


    Full Text Available Introduction: The investigation of myopia and soft contact lenses is not new. Many reports show  that  the  wearing  of  silicone  hydrogel lenses as opposed to conventional disposable hydrogel lenses results in little progression of myopia in the eyes wearing silicone hydrogels. Method: Six subjects wore a silicone hydro-gel lens on one eye while the other eye wore a habitual disposable hydrogel lens for six months of daily wear. Fifty measurements of refractive state in each eye were taken prior to the subjects wearing a silicone lens in one eye and a conven-tional hydrogel lens in the other eye. After six months of daily wear another fifty measurements of refractive state were taken for each subject. Results:  Although  there  is  no  statisti-cal  support  for  the  findings  of  this  study, comet stereo-pairs are used to show the chang-es in refractive state for each subject. Four of  the  six  subjects  showed  an  increase  in myopia in the eye wearing the silicone lens. Discussion:  The  increase  in  myopia in eyes wearing a silicone hydrogel lens is contrary  to  the  findings  of  other  studies.

  16. Sliding wear of conventional and nanostructured cemented carbides

    Energy Technology Data Exchange (ETDEWEB)

    Jia, K. [Stevens Inst. of Tech., Hoboken, NJ (United States). Dept. of Materials Science and Engineering; Fischer, T.E. [Stevens Inst. of Tech., Hoboken, NJ (United States). Dept. of Materials Science and Engineering


    The sliding wear mechanisms of cemented carbide and the effects of the microstructure scale on the wear resistance were investigated by performing a series of unlubricated sliding wear tests in air with pins of WC-Co composites sliding against silicon nitride disks. In the first approximation, the wear rate is proportional to the hardness with a wear coefficient k=6.9x10{sup -6} for all materials. In the conventional cermets, the wear coefficient k also depends on the grain size; materials with smaller WC grains exhibit a smaller wear resistance. This reduction, however, does not extend to the nanostructured materials which exhibit the above value for k: Their wear resistance is higher than that of conventional cermets in proportion to their hardness. The data can also be expressed in terms of cobalt content: The lower the cobalt content, the lower the wear; but two different such dependencies exist, one for the conventional and one for the nanostructured materials with lower wear. The sliding wear of WC-Co composites occurs on a very small scale: The worn surfaces show no evidence of fracture of plastic deformation. This wear behavior is explained by the hexagonal structure and the anisotropic mechanical behavior of the WC grains that are capable of shear in a limited number of planes but are not capable of triaxial deformation. The higher wear resistance of the nanostructured composites is related to their hardness which decreases the real area of contact. (orig.)

  17. Influence of prolonged wearing of unstable shoes on upright standing postural control. (United States)

    Sousa, Andreia S P; Macedo, Rui; Santos, Rubim; Sousa, Filipa; Silva, Andreia; Tavares, João Manuel R S


    To study the influence of prolonged wearing of unstable shoes on standing postural control in prolonged standing workers. The participants were divided into two groups: one wore unstable shoes while the other wore conventional shoes for 8weeks. Stabilometry parameters related to centre of pressure (CoP), rambling (RM) and trembling (TR) as well as the total agonist/antagonist muscle activity, antagonist co-activation and reciprocal activation were evaluated during upright standing, before and after the 8weeks period. In both moments, the subjects were evaluated wearing the unstable shoes and in barefoot. The unstable shoe condition presented increased CoP displacement related variables and decreased co-activation command compared to barefoot before and after the intervention. The prolonged wearing of unstable shoes led to: (1) reduction of medial-lateral CoP root mean square and area; (2) decreased anteroposterior RM displacement; (3) increased anteroposterior RM mean velocity and mediolateral RM displacement; (4) decreased anteroposterior TR RMS; and (5) increased thigh antagonist co-activation in the unstable shoe condition. The unstable shoe condition is associated to a higher destabilising effect that leads to a selection of more efficient and accurate postural commands compared to barefoot. Prolonged wearing of unstable shoes provides increased effectiveness and performance of the postural control system, while wearing of unstable shoes in upright standing, that are reflected by changes in CoP related variables and by a reorganisation of postural control commands. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Wear Improvement of Tools in the Cold Forging Process for Long Hex Flange Nuts

    Directory of Open Access Journals (Sweden)

    Shao-Yi Hsia


    Full Text Available Cold forging has played a critical role in fasteners and has been widely used in automotive production, manufacturing, aviation and 3C (Computer, Communication, and Consumer electronics. Despite its extensive use in fastener forming and die design, operator experience and trial and error make it subjective and unreliable owing to the difficulty of controlling the development schedule. This study used finite element analysis to establish and simulate wear in automotive repair fastener manufacturing dies based on actual process conditions. The places on a die that wore most quickly were forecast, with the stress levels obtained being substituted into the Archard equation to calculate die wear. A 19.87% improvement in wear optimization occurred by applying the Taguchi quality method to the new design. Additionally, a comparison of actual manufacturing data to simulations revealed a nut forging size error within 2%, thereby demonstrating the accuracy of this theoretical analysis. Finally, SEM micrographs of the worn surfaces on the upper punch indicate that the primary wear mechanism on the cold forging die for long hex flange nuts was adhesive wear. The results can simplify the development schedule, reduce the number of trials and further enhance production quality and die life.


    Directory of Open Access Journals (Sweden)

    Abdul Sharief


    Full Text Available In the present investigation, Al2024–Beryl particulate composites were fabricated by stir casting by varying the weight percentage of beryl particulates from 0 wt% to 10 wt% in steps of 2 wt%. The cast Al2024 alloy and its composites have been subjected to solutionizing treatment at a temperature of 495°C for 2 hrs, followed by ice quenching. Microstructural studies were carried out to determine the nature of the structure. The Brinell hardness test was conducted on both the Al2024 alloy and its composites before and after solutionizing. Pin-on disc wear tests were conducted to examine the wear behavior of the Al2024 alloy and its composites. Sliding wear tests were conducted at various applied loads, sliding velocities and sliding distances. The results reveal that the wear rate of the composites is lower than that of the matrix alloy. The wear rate increased with an increasing applied load and sliding distance, and decreased with increasing sliding velocity.

  20. Corneo-scleral limbal changes following short-term soft contact lens wear. (United States)

    Consejo, Alejandra; Bartuzel, Maciej M; Iskander, D Robert


    To assess whether short-term soft contact lens wear alters the anterior eye surface. Twenty-two neophyte subjects wore soft contact lenses for a period of five hours. Topography based corneo-scleral limbal radius estimates were derived from height measurements acquired with a corneo-scleral profilometer. Additionally, central corneal thickness (CCT), anterior chamber depth (ACD), corneal curvature radius (R) and white-to-white (WTW) diameter were acquired with an OCT-assisted biometer. Measurements were obtained without lens wear (baseline), immediately after lens removal following five hours of wear and three hours after lens removal. Short-term soft contact lens wear significantly modifies corneo-scleral limbal radius (mean±SD: 130±74μm, p < 0.001) and the changes are repeatable. In contrast, the WTW diameter and R were not modified. ACD and CCT were significantly affected but no significant correlations were found between the increment of the limbal radius and the decrease in ACD and CCT. Limbal radius increment was reversed three hours after lens removal for 68% of the subjects but the time course of this reversal was not uniform. It is possible to accurately quantify limbal radius changes as a consequence of soft contact lens wear. The increment in the limbal diameter could reach over 0.5mm but that alteration does not correspond to changes in WTW diameter and it was not observable to the examiner using a slit lamp. Assessing topographical limbus after contact lens wear could be a tool to optimize the selection of the contact lens, from the perspective of anterior eye surface changes. Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  1. Mask-wearing and respiratory infection in healthcare workers in Beijing, China

    Directory of Open Access Journals (Sweden)

    Peng Yang

    Full Text Available OBJECTIVES: The aim of the study was to determine rates of mask-wearing, of respiratory infection and the factors associated with mask-wearing and of respiratory infection in healthcare workers (HCWs in Beijing during the winter of 2007/2008. METHODS: We conducted a survey of 400 HCWs working in eight hospitals in Beijing by face to face interview using a standardized questionnaire. RESULTS: We found that 280/400 (70.0% of HCWs were compliant with mask-wearing while in contact with patients. Respiratory infection occurred in 238/400 (59.5% subjects from November, 2007 through February, 2008. Respiratory infection was higher among females (odds ratio [OR], 2.00 [95% confidence interval {CI}, 1.16-3.49] and staff working in larger hospitals (OR, 1.72 [95% CI, 1.092.72], but was lower among subjects with seasonal influenza vaccination (OR, 0.46 [95% CI, 0.280.76], wearing medical masks (reference: cotton-yarn; OR, 0.60 [95% CI, 0.39-0.91] or with good mask-wearing adherence (OR, 0.60 [95% CI, 0.37-0.98]. The risk of respiratory infection of HCWs working in low risk areas was similar to that of HCWs in high risk area. CONCLUSION: Our data suggest that female HCWs and staffs working in larger hospitals are the focus of prevention and control of respiratory infection in Beijing hospitals. Mask-wearing and seasonal influenza vaccination are protective for respiratory infection in HCWs; the protective efficacy of medical masks is better than that of cotton yarn ones; respiratory infection of HCWs working in low risk areas should also be given attention.

  2. Physiological responses wearing MOPP-IV after atropine and pralidoxime administration in warm and cool environments

    Energy Technology Data Exchange (ETDEWEB)

    Kolka, M.A.; Cadarette, B.S.


    The effect of cholinolytic and oxime (2 mg atropine + 600 mg pralidoxime) therapy on temperature regulation was evaluated in 8 subjects wearing chemical warfare protective clothing (MOPP-level IV). Subjects were tested in two environments: 35 c, 60% rh and 13 C, 44% rh during very light physical activity (1-2 Met) over a six-hour period. Sweating was suppressed approximately 40% by atropine and pralidoxime, and heart rate increased approximately 30 beats/min with drug treatment. At 13 C, all eight subjects completed 350 minutes of exposure in both drug and control experiments. Rectal temperature (t sub re) averaged 38.24 C in both treatments when subjects terminated their exposure at 35 C. Mean skin temperature averaged 37.42 C for both groups at termination. The treatment of subjects with atropine and pralidoxime when wearing chemical protective clothing does not adversely affect the length of time individuals can remain in a cool environment during very light work. However, the wearing of chemical protective clothing will decrease exposure time significantly (approx. 40%) in both control and drug treated subjects in a warm environment.

  3. Healthy Contact Lens Wear and Care

    Centers for Disease Control (CDC) Podcasts


    In this podcast, CDC’s Dr. Jennifer Cope explains some basic steps for proper wear and care of soft contact lenses.  Created: 2/4/2014 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 2/4/2014.

  4. Friction measurement in a hip wear simulator. (United States)

    Saikko, Vesa


    A torque measurement system was added to a widely used hip wear simulator, the biaxial rocking motion device. With the rotary transducer, the frictional torque about the drive axis of the biaxial rocking motion mechanism was measured. The principle of measuring the torque about the vertical axis above the prosthetic joint, used earlier in commercial biaxial rocking motion simulators, was shown to sense only a minor part of the total frictional torque. With the present method, the total frictional torque of the prosthetic hip was measured. This was shown to consist of the torques about the vertical axis above the joint and about the leaning axis. Femoral heads made from different materials were run against conventional and crosslinked polyethylene acetabular cups in serum lubrication. Regarding the femoral head material and the type of polyethylene, there were no categorical differences in frictional torque with the exception of zirconia heads, with which the lowest values were obtained. Diamond-like carbon coating of the CoCr femoral head did not reduce friction. The friction factor was found to always decrease with increasing load. High wear could increase the frictional torque by 75%. With the present system, friction can be continuously recorded during long wear tests, so the effect of wear on friction with different prosthetic hips can be evaluated. © IMechE 2016.

  5. Illumination methods for optical wear detection

    NARCIS (Netherlands)

    Zhang, Jindang; Regtien, Paulus P.L.


    The paper presents some results of a study on optical wear detection. The focus of the paper is on the illumination, to optimize the contrast of the images. Various illumination methods are compared: bright field versus dark field illumination, and various kind of light sources: laser light, diffuse

  6. Tribology: Friction, lubrication, and wear technology (United States)

    Blau, Peter J.


    The topics are presented in viewgraph form and include the following: introduction and definitions of terms; friction concepts; lubrication technology concepts; wear technology concepts; and tribological transitions. This document is designed for educators who seek to teach these concepts to their students.

  7. Childhood intelligence and early tooth wear patterns. (United States)

    Heikkinen, Tuomo; Rusanen, Jaana; Sato, Koshi; Pesonen, Paula; Harila, Virpi; Alvesalo, Lassi


    The aim of this study is to explore the relationships between early dental wear patterns and preschool IQ (Intelligence Quotient, by Stanford-Binet) of the child to illuminate the historic relationship of mental queries and bruxism. The dental study participants were 864 Euro-American preschool and school children whose IQs were tested for school maturity purposes at the age of 4 years, followed by dental data in a cross-sectional manner at the mean age of 7.8 years. Worn dentitions were classified as "symmetric" or "right-" and "left-sided," based on the faceting of the teeth. In general, the relationships of tooth wear and intelligence were scarce, reflecting social background factors. Statistically significant results between asymmetric wear and gender groups suggest that direction of jaw function has a role in the regulation of processes responsible for individual mental performance in childhood. Increased left-side tooth wear and early advantage in the intelligence test in girls is intriguing due to the fact that they reach maturity earlier than boys in verbal articulation, controlled in most cases by the limited area on the left side of the brain.

  8. ERRATUM: Work smart, wear your hard hat

    CERN Multimedia


    An error appeared in the article «Work smart, wear your hard hat» published in Weekly Bulletin 27/2003, page 5. The impact which pierced a hole in the hard hat worn by Gerd Fetchenhauer was the equivalent of a box weighing 5 kg and not 50 kg.

  9. Saliva Parameters and Erosive Wear in Adolescents

    NARCIS (Netherlands)

    Zwier, N.; Huysmans, M. C. D. N. J. M.; Jager, D. H. J.; Ruben, J.; Bronkhorst, E. M.; Truin, G. J.


    The aim of this study was to investigate the relationship between several parameters of saliva and erosive wear in adolescents. (Un-)stimulated saliva was collected from 88 adolescents with erosion and 49 controls (age 16 +/- 1 years). Flow rate, pH and buffer capacity were determined immediately.

  10. Wear-Out Sensitivity Analysis Project Abstract (United States)

    Harris, Adam


    During the course of the Summer 2015 internship session, I worked in the Reliability and Maintainability group of the ISS Safety and Mission Assurance department. My project was a statistical analysis of how sensitive ORU's (Orbital Replacement Units) are to a reliability parameter called the wear-out characteristic. The intended goal of this was to determine a worst case scenario of how many spares would be needed if multiple systems started exhibiting wear-out characteristics simultaneously. The goal was also to determine which parts would be most likely to do so. In order to do this, my duties were to take historical data of operational times and failure times of these ORU's and use them to build predictive models of failure using probability distribution functions, mainly the Weibull distribution. Then, I ran Monte Carlo Simulations to see how an entire population of these components would perform. From here, my final duty was to vary the wear-out characteristic from the intrinsic value, to extremely high wear-out values and determine how much the probability of sufficiency of the population would shift. This was done for around 30 different ORU populations on board the ISS.

  11. Tribology: Friction, lubrication, and wear technology (United States)

    Blau, Peter J.


    The topics are presented in viewgraph form and include the following: introduction and definitions of terms; friction concepts; lubrication technology concepts; wear technology concepts; and tribological transitions. This document is designed for educators who seek to teach these concepts to their students.

  12. Do reef fish habituate to diver presence? Evidence from two reef sites with contrasting historical levels of SCUBA intensity in the Bay Islands, Honduras.

    Directory of Open Access Journals (Sweden)

    Benjamin M Titus

    Full Text Available Contact between humans and the marine environment is increasing, but the capacity of communities to adapt to human presence remains largely unknown. The popularization of SCUBA diving has added a new dimension to human impacts in aquatic systems and, although individual-level impacts have been identified, cumulative effects on ecosystem function and community-wide responses are unclear. In principle, habituation may mitigate the consequences of human presence on the biology of an individual and allow the quick resumption of its ecological roles, but this has not been documented in aquatic systems. Here, we investigate the short-term impact of human presence and the long-term habituation potential of reef-fish communities to recreational SCUBA divers by studying symbiotic cleaning interactions on coral reefs with differing levels of historical contact with divers. We show that incidences of human contact result in a smaller decline in ecosystem function and more rapid resumption of baseline services on a reef in Utila, Honduras that has heavy historical levels of SCUBA diver presence, compared to an un-dived reef site in the Cayos Cochinos Marine Protected Area (CCMPA. Nonetheless, despite the generally smaller change in ecosystem function and decades of regular contact with divers, cleaning behavior is suppressed by >50% at Utila when divers are present. We hypothesize that community-wide habituation of reef fish is not fully achievable and may be biologically restricted to only partial habituation. Differential responses to human presence impacts the interpretation and execution of behavioral research where SCUBA is the predominant means of data collection, and provides an important rationale for future research investigating the interplay between human presence, ecosystem function, and community structure on coral reefs.

  13. Long-term Efficacy of Orthokeratology Contact Lens Wear in Controlling the Progression of Childhood Myopia. (United States)

    Santodomingo-Rubido, Jacinto; Villa-Collar, César; Gilmartin, Bernard; Gutiérrez-Ortega, Ramón; Sugimoto, Keiji


    The primary outcome of this study is to compare the axial length growth of white European myopic children wearing orthokeratology contact lenses (OK) to a control group (CT) over a 7-year period. Subjects 6-12 years of age with myopia -0.75 to -4.00DS and astigmatism ≤1.00DC were prospectively allocated OK or distance single-vision spectacles (SV) correction. Measurements of axial length (Zeiss IOLMaster), corneal topography, and cycloplegic refraction were taken at 6-month intervals over a 2-year period. Subjects were invited to return to the clinic approximately 5 years later (i.e., 7 years after the beginning of the study) for assessment of their ocular refractive and biometric components. The CT consisted of 4 SV and 12 subjects who switched from SV to soft contact lens wear after the initial 2 years of SV lens wear. Changes in axial length relative to baseline over a 7-year period were compared between groups. Fourteen and 16 subjects from the OK and CT groups, respectively, were examined 6.7 ± 0.5 years after the beginning of the study. Statistically significant changes in the axial length were found over time and between groups (both p < 0.001), but not for the time*group interaction (p = 0.125). The change in the axial length for the OK group was 22% (p = 0.328), 42% (p = 0.007), 40% (p = 0.020), 41% (p = 0.013), and 33% (p = 0.062) lower than the CT group following 6, 12, 18, 24, and 84 months of lens wear, respectively. A trend toward a reduction in the rate of axial elongation of the order of 33% was found in the OK group in comparison to the CT group following 7 years of lens wear.

  14. Instagram Shows How Diabetics Really Wear a Glucose Monitor (United States)

    ... page: Instagram Shows How Diabetics Really Wear a Glucose Monitor ... and her colleagues searched the social media site Instagram. They found 353 posts featuring people wearing Dexcom ...

  15. Corrosive wear. Evaluation of wear and corrosive resistant materials; Noetningskorrosion. Utvaerdering av noetnings- och korrosionsbestaendiga material

    Energy Technology Data Exchange (ETDEWEB)

    Persson, H.; Hjertsen, D.; Waara, P.; Prakash, B.; Hardell, J.


    With a new purchase of a waste conveyer screw at hand, for the 'A-warehouse' at the combined power and heating plant at E.ON Norrkoeping, the request for improved construction materials was raised. The previous screw required maintenance with very short intervals due to the difficult operation conditions. With the new screw the expectation is to manage 6 months of operation without interruption. The environment for the screw has two main components that sets the demand on the materials, on one hand the corrosive products that comes along and which forms at digestion of the waste and on the other hand the abrasive content in the waste. The term of the mechanism is wear-corrosion and can give considerably higher material loss than the two mechanisms wear and corrosion separately. Combination of a strong corrosive environment together with extensive wear is something that we today have limited knowledge about. The overall objective of the project has been to establish better wear and corrosive resistant construction materials for a waste conveyer screw that will lead to reduced operational disturbance costs. The evaluation has been performed in both controlled laboratory environments and in field tests, which has given us a better understanding of what materials are more suitable in this tough environment and has given us a tool for future predictions of the wear rate of the different material. The new conveyer screw, installed in February 2007 and with which the field test have been performed, has considerably reduced the wear of the construction and the target of 6 month maintenance-free operation is met with this screw for all the evaluated materials. The wear along the screw varies very much and with a clear trend for all the materials to increase towards the feeding direction of the screw. As an example, the wear plate SS2377 (stainless duplex steel) has a useful life at the most affected areas that is calculated to be 1077 days of operation with the


    Directory of Open Access Journals (Sweden)

    E. M. Farhadzadeh


    Full Text Available Reconditioning of the power generating unit worn equipment and devices is conducted during the scheduled repair period. Quality of wear reconditioning is evaluated by technical state and repair work implementation. Quality of the repair work execution characterizes logistical activities of the power station and the repair services and is rated by a five-grade scale. There are three technical conditions: adequate, subject to reservations, falling short of the technical standard documentation requirements. In practical work these constraints give place to essential ambiguity of the decision. Further to regulating techniques by way of informational support, the authors propose conducting the wear-reconditioning quality evaluation (repair quality accordingly the technical-and-economic indexes pattern of change. The paper recommends applying similarly the fivegrade system in evaluating the power generating unit technical state and distinguishes intolerable, dissatisfactory, fair, good and model estimates. The study demonstrates the assessment criteria dependence on the character of reliability and economical efficiency of performance variation after the repair with increase or decrease of the technical-and-economic indexes in reference to their mean, minimum and maximum values before the repair. The cases ascribed to intolerable quality of the wear reconditioning are those with one or more technical-and-economic indexes that not only failed to improve their values but deteriorated, and at that they became the worst amongst observable values. The model quality estimate of the wear reconditioning is allotted under condition that the power unit technical-and-economic index valuations after the repair not merely improved but also exceeded the best among those under observation. The developed method and algorithm for quality evaluation of the scheduled repair implementation contribute to practical realization of the independent monitoring. This monitoring

  17. Occlusion and temporomandibular function among subjects with mandibular distal extension removable partial dentures

    NARCIS (Netherlands)

    Creugers, N.H.J.; Witter, D.J.; Spijker, A. van 't; Gerritsen, A.E.; Kreulen, C.M.


    Objective. To quantify effects on occlusion and temporomandibular function of mandibular distal extension removable partial dentures in shortened dental arches. Methods. Subjects wearing mandibular extension removable partial dentures (n = 25) were compared with subjects with shortened dental arches

  18. Corneal response to different oxygen levels during extended wear. (United States)

    Rivera, R K; Polse, K A


    In this study we explored the relationship between hypoxic exposure level and corneal response by assuming that the partial pressure of oxygen (PO2) under a contact lens during eye closure is directly related to oxygen transmissibility (Dk/L). To study this relationship, we monitored a group of subjects who wore RGP lenses of various Dk/L values on an extended wear basis. The results revealed that as Dk/L increases, there is a substantial decrease in overnight corneal edema and epithelial microcysts. However, other responses seemingly related to purely mechanical properties (e.g., lens adherence, corneal topographical changes, and 3-9 limbal superficial punctate keratitis) appear to be independent of Dk/L. Results also suggest that sufficient PO2 levels under a contact lens can minimize endothelial morphological changes associated with hypoxia. We conclude that metabolically driven complications accompanying RGP extended wear can be substantially eliminated with lenses having Dk/L values of 80 x 10(-9) (cm x mL O2)/(sec x mL x mm Hg) or greater.

  19. Measurement and Evaluation of Wear Frogs Switches ŽSR

    Directory of Open Access Journals (Sweden)

    Urda Ján


    Full Text Available This paper deals with the measurement and evaluation of wear frogs switches ZSR. One of the main problems is the oversize wear. The possibilities analysis of this problem is offered through a set of switches and monitoring of selected parameters. One of these parameters is also monitoring the vertical wear

  20. 46 CFR 169.825 - Wearing of safety belts. (United States)


    ... 46 Shipping 7 2010-10-01 2010-10-01 false Wearing of safety belts. 169.825 Section 169.825 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS SAILING SCHOOL VESSELS Operations § 169.825 Wearing of safety belts. The master of each vessel shall ensure that each person wears...

  1. Sleep bruxism in individuals with and without attrition-type tooth wear: An exploratory matched case-control electromyographic study. (United States)

    Jonsgar, Christine; Hordvik, Paul-Arne; Berge, Morten E; Johansson, Ann-Katrin; Svensson, Peter; Johansson, Anders


    To examine if there is a difference in possible sleep bruxism activity (SB) in subjects with or without attrition-type tooth wear. Sixteen individuals with pronounced attritional-type tooth wear were compared with sex and aged matched controls without tooth wear by means of measurement of electromyographic (EMG) activity during a minimum of four consecutive nights of sleep. Mean age and range for the study- and control- group was 23.7 years (range 19.9-28.5) and 23.6 years (range 20.3-27.9), respectively. There were 11 females and five males in each of the two groups. The attrition group presented incisal/occlusal attrition wear into dentin and matching wear facets between opposing anterior teeth. The controls had negligible signs of incisal/occlusal wear and a minimal number of matching wear facets. The prevalence of both self-reported and partner-reported SB was significantly more common in the attrition group compared to the controls (P=0.04 and P=0.007, respectively). Self-reported morning facial pain was similarly more common in the attrition group (P=0.014). Maximum opening capacity, number of muscles painful to palpation, salivary flow rate and buffering capacity were not significantly different between the groups. Interestingly, none of the measures of jaw muscle EMG activity during sleep, as recorded by the portable EMG equipment, differed significantly between the attrition group and the matched controls (P>0.05). The results from this exploratory study suggest that there is no difference in EMG activity between subjects with and without attrition-type tooth wear. Further research is needed in order to substantiate these preliminary findings. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  2. Biomechanics of postoperative shoes: plantar pressure distribution, wearing characteristics and design criteria: a preliminary study. (United States)

    Schuh, Reinhard; Trnka, Hans-Joerg; Sabo, Anton; Reichel, Martin; Kristen, Karl-Heinz


    Modern concepts in the postoperative treatment of first metatarsal osteotomies include special shoes that should decrease stress in the forefoot region. The purpose of this study was to determine plantar pressure distribution, wearing characteristics and stress-reducing effectiveness of five different types of commonly used postoperative shoes. Additionally, we wanted to modify the shoe that revealed the most favourable results in a way that improves forefoot relief as well as provides comfort to the patients. Eight persons consented to participate in the study. Plantar pressure distribution in five different types of postoperative shoes (Rathgeber(®) normal, Rathgeber(®) modified, 4. Darco(®) flat, Darco(®) VFE, Wocker(®)) was assessed using Mediologic(®) insoles. Also, subjective criteria considering wearing comfort, stability and rolling characteristics were evaluated. Based on the postoperative shoe revealing the most favourable results, further prototypes were developed. Each new model was targeted to meet the given requirements, minimal forefoot pressure, in a different way. The Rathgeber(®) modified model revealed the most favourable results concerning plantar pressure distribution as well as subjective wearing characteristics. Therefore, it was chosen for further modifications. After adding an extra layer of high elastic and springy material for shock absorption at the hallux region, forefoot relief and wearing characteristics showed improved results. The results of the present study indicate that damping material in the hallux region of postoperative shoes minimises stress in this region and improves patient's comfort.

  3. Predicting success with orthokeratology lens wear: a retrospective analysis of ocular characteristics. (United States)

    Carkeet, N L; Mountford, J A; Carney, L G


    Orthokeratology procedures suffer from lack of predictability in the response of individuals. To identify factors contributing to this, we have retrospectively studied a range of ocular parameters in patients with varying outcomes from orthokeratology lens wear. Three groups were studied: an experimental group (9 subjects wearing Contex OK-3 design orthokeratology contact lenses), and 2 control groups [10 rigid gas permeable (RGP) contact lens wearers and 10 non-contact lens wearers]. Three categories were identified among the orthokeratology group: those responding well, moderately, or poorly to orthokeratology lens wear. Measurements included subjective refraction, intraocular distances, corneal thickness, ocular rigidity, and epithelial fragility. When comparing the three orthokeratology categories, there was no significant difference for central and peripheral epithelial fragility and ocular rigidity. There was also no significant difference for any of the biometric characteristics measured. The prefitting spherical equivalent power was found to be significantly different between categories of responders (p = 0.0228), with the poor responders having the highest initial level of myopia. None of the measured characteristics differed significantly among the orthokeratology group and the two control groups. In this pilot study, the success of orthokeratology lens wear was not related to ocular biomechanical or biometric attributes, but it was related to prefitting refractive error.

  4. Is tooth wear in the primary dentition predictive of tooth wear in the permanent dentition? Report from a longitudinal study.

    LENUS (Irish Health Repository)

    Harding, M A


    To determine the prevalence of tooth wear in the permanent dentition of a sample of 12-year-old school children and establish whether an association exists between tooth wear recorded now and tooth wear recorded in their primary dentition at age five.

  5. Aluminum nanocomposites having wear resistance better than stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    An, Linan [University of Central Florida; Qu, Jun [ORNL; Luo, Jinsong [Chinese Academy of Sciences; Fan, Yi [Chinese Academy of Sciences; Zhang, Ligong [University of Central Florida; Liu, Jinling [University of Central Florida; Xu, Chengying [University of Central Florida; Blau, Peter Julian [ORNL


    Tribological behavior of alumina-particle-reinforced aluminum composites made by powder metallurgy process has been investigated. The nanocomposite containing 15 vol% of Al2O3 nanoparticles exhibits excellent wear resistance by showing significantly low wear rate and abrasive wear mode. The wear rate of the nanocomposite is even lower than stainless steel. We have also demonstrated that such excellent wear resistance only occurred in the composite reinforced with the high volume fraction of nanosized reinforcing particles. The results were discussed in terms of the microstructure of the nanocomposite.

  6. Finger wear detection for production line battery tester (United States)

    Depiante, Eduardo V.


    A method for detecting wear in a battery tester probe. The method includes providing a battery tester unit having at least one tester finger, generating a tester signal using the tester fingers and battery tester unit with the signal characteristic of the electrochemical condition of the battery and the tester finger, applying wavelet transformation to the tester signal including computing a mother wavelet to produce finger wear indicator signals, analyzing the signals to create a finger wear index, comparing the wear index for the tester finger with the index for a new tester finger and generating a tester finger signal change signal to indicate achieving a threshold wear change.

  7. Exposure and risks from wearing asbestos mitts

    Directory of Open Access Journals (Sweden)

    Tindall Matthew


    Full Text Available Abstract Background Very high fibre inhalation exposure has been measured while people were wearing personal protective equipment manufactured from chrysotile asbestos. However, there is little data that relates specifically to wearing asbestos gloves or mitts, particularly when used in hot environments such as those found in glass manufacturing. The aim of this study was to assess the likely personal exposure to asbestos fibres when asbestos mitts were used. Results Three types of work activity were simulated in a small test room with unused mitts and artificially aged mitts. Neither pair of mitts were treated to suppress the dust emission. The measured respirable fibre exposure levels ranged from Conclusion People who wore asbestos mitts were likely to have been exposed to relatively low levels of airborne chrysotile asbestos fibres, certainly much lower than the standards that were accepted in the 1960's and 70's. The cancer risks from this type of use are likely to be very low.

  8. Scuba diving and otology: a systematic review with recommendations on diagnosis, treatment and post-operative care. (United States)

    Livingstone, Devon M; Smith, Kristine A; Lange, Beth


    Scuba diving is a popular recreational and professional activity with inherent risks. Complications related to barotrauma and decompression illness can pose significant morbidity to a diver's hearing and balance systems. The majority of dive-related injuries affect the head and neck, particularly the outer, middle and inner ear. Given the high incidence of otologic complications from diving, an evidence-based approach to the diagnosis and treatment of otic pathology is a necessity. We performed a systematic and comprehensive literature review including the pathophysiology, diagnosis, and treatment of otologic pathology related to diving. This included inner, middle, and outer ear anatomic subsites, as well as facial nerve complications, mal de debarquement syndrome, sea sickness and fitness to dive recommendations following otologic surgery. Sixty-two papers on diving and otologic pathology were included in the final analysis. We created a set of succinct evidence-based recommendations on each topic that should inform clinical decisions by otolaryngologists, dive medicine specialists and primary care providers when faced with diving-related patient pathology.

  9. The JCMT Gould Belt Survey: A First Look at the Auriga–California Molecular Cloud with SCUBA-2 (United States)

    Broekhoven-Fiene, H.; Matthews, B. C.; Harvey, P.; Kirk, H.; Chen, M.; Currie, M. J.; Pattle, K.; Lane, J.; Buckle, J.; Di Francesco, J.; Drabek-Maunder, E.; Johnstone, D.; Berry, D. S.; Fich, M.; Hatchell, J.; Jenness, T.; Mottram, J. C.; Nutter, D.; Pineda, J. E.; Quinn, C.; Salji, C.; Tisi, S.; Hogerheijde, M. R.; Ward-Thompson, D.; Bastien, P.; Bresnahan, D.; Butner, H.; Chrysostomou, A.; Coude, S.; Davis, C. J.; Duarte-Cabral, A.; Fiege, J.; Friberg, P.; Friesen, R.; Fuller, G. A.; Graves, S.; Greaves, J.; Gregson, J.; Holland, W.; Joncas, G.; Kirk, J. M.; Knee, L. B. G.; Mairs, S.; Marsh, K.; Moriarty-Schieven, G.; Mowat, C.; Rawlings, J.; Richer, J.; Robertson, D.; Rosolowsky, E.; Rumble, D.; Sadavoy, S.; Thomas, H.; Tothill, N.; Viti, S.; White, G. J.; Wilson, C. D.; Wouterloot, J.; Yates, J.; Zhu, M.


    We present 850 and 450 μm observations of the dense regions within the Auriga–California molecular cloud using SCUBA-2 as part of the JCMT Gould Belt Legacy Survey to identify candidate protostellar objects, measure the masses of their circumstellar material (disk and envelope), and compare the star formation to that in the Orion A molecular cloud. We identify 59 candidate protostars based on the presence of compact submillimeter emission, complementing these observations with existing Herschel/SPIRE maps. Of our candidate protostars, 24 are associated with young stellar objects (YSOs) in the Spitzer and Herschel/PACS catalogs of 166 and 60 YSOs, respectively (177 unique), confirming their protostellar nature. The remaining 35 candidate protostars are in regions, particularly around LkHα 101, where the background cloud emission is too bright to verify or rule out the presence of the compact 70 μm emission that is expected for a protostellar source. We keep these candidate protostars in our sample but note that they may indeed be prestellar in nature. Our observations are sensitive to the high end of the mass distribution in Auriga–Cal. We find that the disparity between the richness of infrared star-forming objects in Orion A and the sparsity in Auriga–Cal extends to the submillimeter, suggesting that the relative star formation rates have not varied over the Class II lifetime and that Auriga–Cal will maintain a lower star formation efficiency.

  10. Risk factors and causative organisms in microbial keratitis in daily disposable contact lens wear. (United States)

    Stapleton, Fiona; Naduvilath, Thomas; Keay, Lisa; Radford, Cherry; Dart, John; Edwards, Katie; Carnt, Nicole; Minassian, Darwin; Holden, Brien


    This study investigated independent risk factors and causative organisms in microbial keratitis in daily disposable contact lens (CL)-wearers. A multisite prospective case-control study was undertaken. Cases were daily disposable CL-wearers attending Moorfields Eye Hospital with microbial keratitis and those reported through a one-year surveillance study in Australia and in New Zealand. A population-based telephone survey identified daily disposable CL-wearing controls. Subjects completed a questionnaire describing CL-wear history, hygiene and demographics. The sample used for risk factor analysis was weighted in proportion to the CL-wearing population at each location. Corneal scrape results were accessed. Independent risk factors were determined using multiple binary logistic regression. Causative organisms in different CL-wear modalities were compared using a chi-squared test. 963 daily disposable CL-wearers were identified, from which 67 cases and 374 controls were sampled. Independent risk factors were; wearing CLs every day compared with less frequent use (OR 10.4x; 95% CI 2.9-56.4), any overnight wear (OR 1.8x; 95% CI 1.6-2.1), less frequent hand washing (OR 1.8x; 95% CI 1.6-2.0), and smoking (OR 1.3x; 95% CI 1.1-1.6). Certain daily disposable CLs (OR 0.2x; 95% CI 0.1-0.2) had protective effects. Environmental organisms were less frequently recovered with daily disposable CLs (20%), compared with other modalities (36%; pkeratitis with daily disposable CLs. Risk varied with daily disposable CL type. The profile of causative organisms is consistent with less severe disease.

  11. Effect of wearing a ski helmet on perception and localization of sounds. (United States)

    Ruedl, G; Kopp, M; Burtscher, M; Zorowka, P; Weichbold, V; Stephan, K; Koci, V; Seebacher, J


    Helmet use on ski slopes has steadily increased worldwide over the past years. A common reason reported for helmet non-use, however, is impaired hearing. Therefore, an intra-subject design study was conducted to compare hearing thresholds and sound source localization of 21 adults with normal hearing in an anechoic chamber when wearing a ski helmet and ski goggles or wearing a ski cap and ski goggles to the condition head bare. Hearing thresholds while wearing a ski helmet (6.8 ± 1.6 dB HL) and ski cap (5.5 ± 1.6 dB HL) were significantly different (p = 0.030, d = 0.44). Compared to head bare (2.5 ± 1.2 dB HL), a significant difference was found for the ski helmet only (p = 0.040, d = 1.57). Regarding sound source localization, correct scores in the condition head bare (90%) showed a highly significant difference compared with those of condition cap (65%) and helmet (58%), respectively (p 2.5). Compared to the ski cap, wearing the helmet significantly reduced correct scores (p = 0.020, d = 0.59) irrespective of the tested sound pressure levels. In conclusion, wearing a ski helmet impairs hearing to a small though significantly greater extent compared with a cap, the degree, however, being less than what is termed as a hearing impairment. Compared to the condition head bare, wearing a ski cap or a ski helmet significantly reduced one's ability of sound source localization. © Georg Thieme Verlag KG Stuttgart · New York.

  12. Tooth wear and feeding ecology in mountain gorillas from Volcanoes National Park, Rwanda. (United States)

    Galbany, Jordi; Imanizabayo, Olive; Romero, Alejandro; Vecellio, Veronica; Glowacka, Halszka; Cranfield, Michael R; Bromage, Timothy G; Mudakikwa, Antoine; Stoinski, Tara S; McFarlin, Shannon C


    Ecological factors have a dramatic effect on tooth wear in primates, although it remains unclear how individual age contributes to functional crown morphology. The aim of this study is to determine how age and individual diet are related to tooth wear in wild mountain gorillas (Gorilla beringei beringei) from Volcanoes National Park, Rwanda. We calculated the percent of dentine exposure (PDE) for all permanent molars (M1-M3) of known-age mountain gorillas (N = 23), to test whether PDE varied with age using regression analysis. For each molar position, we also performed stepwise multiple linear regression to test the effects of age and percentage of time spent feeding on different food categories on PDE, for individuals subject to long-term observational studies by the Dian Fossey Gorilla Fund International's Karisoke Research Center. PDE increased significantly with age for both sexes in all molars. Moreover, a significant effect of gritty plant root consumption on PDE was found among individuals. Our results support prior reports indicating reduced tooth wear in mountain gorillas compared to western gorillas, and compared to other known-aged samples of primate taxa from forest and savanna habitats. Our findings corroborate that mountain gorillas present very low molar wear, and support the hypothesis that age and the consumption of particular food types, namely roots, are significant determinants of tooth wear variation in mountain gorillas. Future research should characterize the mineral composition of the soil in the Virunga habitat, to test the hypothesis that the physical and abrasive properties of gritty foods such as roots influence intra- and interspecific patterns of tooth wear. © 2015 Wiley Periodicals, Inc.


    Directory of Open Access Journals (Sweden)



    Full Text Available Functionally graded aluminium (Al-Si5Cu3 metal matrix composite reinforced with 10 wt-percent of boron carbide particles having average size of 33 µm was synthesized through horizontal centrifugal casting method. The specimen of length 150 mm and outer diameter of 154 mm with the thickness of 20 mm was produced under the centrifuging speed of 1000 rpm. Composite specimens were prepared as per ASTM standards from the casting and subjected to microstructural evaluation, hardness testing and three body abrasion wear test. The microstructural observation was done on the surfaces at the distance of 1, 2.5, 10 and 15 mm from the outer periphery of the casting and the result shows that larger amount of particles observed at distance of 2.5 mm and very less particles observed at the distance of 15 mm. The hardness test was conducted on the different surfaces in the radial direction from the outer periphery and found decrease in hardness from 2.5 to 15 mm. The abrasion wear test was conducted using dry abrasion tester for various loads of 28, 40 and 52 N at different distances from the outer periphery of the casting and the results revealed that wear rate gradually increases when moving towards the inner periphery and also with the increasing load. Therefore higher wear resistance was observed at the outer periphery and the lower wear resistance was obtained at the inner periphery. This property makes them suitable for using in wear applications such as in cylinder liners.

  14. Wear performance of monolithic dental ceramics with different surface treatments. (United States)

    Preis, Verena; Weiser, Felix; Handel, Gerhard; Rosentritt, Martin


    To investigate the two-body wear performance of monolithic dental ceramics with different surface treatments. Standardized specimens (n = 8/ series) were fabricated from three monolithic dental ceramics (experimental translucent zirconia, experimental shaded zirconia, lithium disilicate). Four groups of each material were defined according to clinically relevant surface treatments: polished, polishedground, polished-ground-repolished, glazed. Two-body wear tests with steatite antagonists were performed in a chewing simulator. Surface roughness (R(a)) was controlled, and wear depths of specimens and antagonistic wear areas were calculated in relation to human enamel as reference. Statistical analysis of wear data was carried out using one-way ANOVA and Bonferroni multiple comparison test for post hoc analysis (α = .05). Scanning electron microscopy was applied for evaluating wear performance of ceramics and antagonists. Polished, ground, and repolished zirconia showed no wear, while glaze was abraded. Irrespective of the surface treatment, wear depth of lithium disilicate was significantly (P grinding and glazing. Steatite surfaces were smooth when opposed to polished/ground/repolished zirconia, and ploughed when opposed to glaze and lithium disilicate. Translucent and shaded experimental zirconia yielded superior wear behavior and lower antagonistic wear compared to lithium disilicate. A trend to higher ceramic and antagonistic wear was shown after grinding and glazing.

  15. Pattern of outsole shoe heel wear in infantry recruits

    Directory of Open Access Journals (Sweden)

    Finestone Aharon S


    Full Text Available Abstract Background Excessive shoe heel abrasion is of concern to patients, parents and shoe manufacturers, but little scientific information is available. The purpose of this study was to describe the phenomenon in a group of infantry recruits performing similar physical activity, and search for biomechanical factors that might be related. Methods Seventy-six subjects (median age 19 enrolled. Pre-training parameters measured included height, weight, tibial length, foot arch height and foot progression angle. Digital plantar pressure maps were taken to calculate arch indexes. Shoe heel abrasion was assessed manually after 14 weeks of training with different-sized clock transparencies and a calliper. Results Outsole abrasion was posterolateral, averaging 12 degrees on each shoe. The average heel volume that was eroded was almost 5 cm3. The angle of maximum wear was related to right foot progression angle (r = 0.27, p = 0.02. Recruits with lateral ankle sprains had higher angles of maximal abrasion (17° versus 10°, p = 0.26 and recruits with lateral heel abrasion had more lateral ankle sprains (14% versus 3%, p = 0.12. Conclusion While shoe heel wear affects many people, very little has been done to measure it. In this study in healthy subjects, we found the main abrasion to be posterolateral. This seems to be related to foot progression angle. It was not related to hindfoot valgus/varus or other factors related to subtalar joint motion. These findings do not warrant modification of subtalar joint motion in order to limit shoe heel abrasion.

  16. Wirelessly Interrogated Wear or Temperature Sensors (United States)

    Woodard, Stanley E.; Taylor, Bryant D.


    Sensors for monitoring surface wear and/or temperature without need for wire connections have been developed. Excitation and interrogation of these sensors are accomplished by means of a magnetic-field-response recorder. In a sensor of the present type as in the previously reported ones, the capacitance and, thus, the resonance frequency, varies as a known function of the quantity of interest that one seeks to determine. Hence, the resonance frequency is measured and used to calculate the quantity of interest.

  17. Contact Thermal Analysis and Wear Simulation of a Brake Block

    Directory of Open Access Journals (Sweden)

    Nándor Békési


    Full Text Available The present paper describes an experimental test and a coupled contact-thermal-wear analysis of a railway wheel/brake block system through the braking process. During the test, the friction, the generated heat, and the wear were evaluated. It was found that the contact between the brake block and the wheel occurs in relatively small and slowly moving hot spots, caused by the wear and the thermal effects. A coupled simulation method was developed including numerical frictional contact, transient thermal and incremental wear calculations. In the 3D simulation, the effects of the friction, the thermal expansion, the wear, and the temperature-dependent material properties were also considered. A good agreement was found between the results of the test and the calculations, both for the thermal and wear results. The proposed method is suitable for modelling the slowly oscillating wear caused by the thermal expansions in the contact area.

  18. Postmarket surveillance of Menicon Z rigid gas-permeable contact lenses for up to 30 days continuous wear in the United States. (United States)

    Albright, Roger A; Venuti, Beverley D; Ichijima, Hideji; Nyunt, Aung Kyaw; Cavanagh, H Dwight


    To evaluate the incidence of microbial keratitis associated with the use of the Menicon Z rigid gas-permeable (RGP) contact lenses (CLs) for up to 30 days continuous wear (CW). For this study, CW was defined as wearing CLs in an extended-wear modality with an average wearing time of 22 days or more. Microbial keratitis was the sole endpoint of the study safety evaluation. Subjects who were interested in RGP lens CW were recruited for the study through 33 investigational practices. To be eligible for the study, subjects must have worn the Menicon Z lens for CW for at least 1.5 months with an average CW time of 22 days or more. Eligible wearers were then contacted at 6-month intervals for up to 24 months after enrollment to determine their typical wearing schedules and continuance of wear and to detect any problems that would be indicative of microbial keratitis. Discontinuation from the study was defined as a discontinuation of contact with or CL wear by the study participants. Study volunteers could be discontinued from the study at 6, 12, 18, or 24 months if they could not be contacted (lost to follow-up); if they were not wearing their CL for CW; or at their own request. Wearing time data collected for individuals discontinued from the study was included in the wearing time analysis. The study population included 507 participants, of whom 173 had discontinued by the end of study at 24 months. Lack of 22 days or more of CW was the most frequently cited reason for discontinuation and accounted for 121 of the 173 subject discontinuations. Lost to follow-up, study participant choice, and other reasons accounted for the remaining 52 subject discontinuations. Of the reported wearing times over the duration of the study, 1,275 of the 1,527 contacts resulted in reported wearing times of 22 days or more of CW. There were no findings of microbial keratitis during the study. Overall, there was a low reported rate of complications for the enrolled study participants. On the

  19. Wear Resistance Assessment of Fluoropolymer Coated Gears

    Directory of Open Access Journals (Sweden)

    Lidia Nedeloni


    Full Text Available Power transmissions that incorporate gears dissipate a significant amount of energy and noise. Thus, any improvement in their performance contributes to reducing energy consumption and noise pollution. In recent years, the opportunities offered by conventional technologies to increase gear performance have been fully exploited. Therefore, surface depositions on gear teeth have become increasingly important technologies in achieving objectives such as: improving energy performance, providing greater protection against superficial defects, increasing load capacity and reducing acoustic emissions generated during operation. However, gear coating technologies have begun to be developed, but the investigations are still insufficient. In this study, we carried out wear resistance investigations performed on fluoropolymer coatings for different working speeds, loads and lubrication conditions. The results point out that the deterioration rate of the coating increases with the increase of the working speed and the applied load. In addition, a slight lubrication, applied at the start of testing, leads to a noticeable improvement in wear behaviour. This study represents one step further in understanding the wear process of fluoropolymer coated gears

  20. Wear model of an excavator bucket (United States)

    Sarychev, Vladimir D.; Granovskii, Alexey Yu.; Nevskii, Sergey A.; Konovalov, Sergey V.; Gromov, Victor E.


    A mathematical model describing wear of the interior faces of the excavator bucket during the long-termed operation is proposed. The model is based on the Navier-Stocks equation and boundary conditions. The bucket was modeled as a rectangular parallelepiped; one of its faces is permeable for a granular material, whereas the others meet the conditions of impermeability and adhesion. In the approximation of viscous fluid, motion equations of a granular material in the excavator bucket were solved by the finite elements method. The velocity distribution curves of material particles along the bucket surface are obtained. A vortex structure is revealed at the bottom-back wall edge of the bucket, and it is thought to be the reason for high wear in these zones. As shown by the granular material pressure distributed along the bucket walls, its maximum is at the bottom-back wall edge of the excavator bucket. It is considered to be the reason for high wear in the operation process. Therefore, the bottom and back walls of the excavator bucket should be coated with a composite armouring mesh via arc surfacing.

  1. Corrosion and wear in plasma electrosurgical devices (United States)

    Gaspredes, J.; Ryan, T. P.; Stalder, K. R.; Woloszko, J.


    Data were previously reported on studies of the effects of electrical discharges on the corrosion and wear of simple, single-wire test devices immersed in isotonic saline 1 . This work showed that there are a wide variety of mechanisms that can explain various aspects of electrode mass loss, even with very simple electrode geometries and operating conditions. It was found that the electrode material composition played an important role. Subsequently, our studies were expanded to include more realistic device geometries and operating conditions. This paper shows the results of studies on wear characteristics of electrodes made from a variety of highly corrosion resistant metals and alloys, including Waspaloy, Hastelloy, Inconel, Havar, Monel, and other pure metals such as Hafnium. All of these metals underwent wear testing under clinically relevant conditions. Depending on the operating conditions, multiple discrete physical and chemical effects were observed at different locations on the surface of an individual millimeter-scale device electrode. Scanning electron microscope (SEM) micrographs, Energy-dispersive X-ray spectroscopy (EDS) and area loss data will be presented for a variety of test conditions and electrode materials.

  2. Phenomenological modeling of abradable wear in turbomachines (United States)

    Berthoul, Bérenger; Batailly, Alain; Stainier, Laurent; Legrand, Mathias; Cartraud, Patrice


    Abradable materials are widely used as coatings within compressor and turbine stages of modern aircraft engines in order to reduce operating blade-tip/casing clearances and thus maximize energy efficiency. However, rubbing occurrences between blade tips and coating liners may lead to high blade vibratory levels and endanger their structural integrity through fatigue mechanisms. Accordingly, there is a need for a better comprehension of the physical phenomena at play and for an accurate modeling of the interaction, in order to predict potentially unsafe events. To this end, this work introduces a phenomenological model of the abradable coating removal based on phenomena reported in the literature and accounting for key frictional and wear mechanisms including plasticity at junctions, ploughing, micro-rupture and machining. It is implemented within an in-house software solution dedicated to the prediction of full three-dimensional blade/abradable coating interactions within an aircraft engine low pressure compressor. Two case studies are considered. The first one compares the results of an experimental abradable test rig and its simulation. The second one deals with the simulation of interactions in a complete low-pressure compressor. The consistency of the model with experimental observations is underlined, and the impact of material parameter variations on the interaction and wear behavior of the blade is discussed. It is found that even though wear patterns are remarkably robust, results are significantly influenced by abradable coating material properties.

  3. Comparison of pattern of failure of resin composite restorations in non-carious cervical lesions with and without occlusal wear facets. (United States)

    Oginni, Adeleke Oke; Adeleke, Adeyinka Adedayo


    Many studies have reported the clinical problems associated with resin composite restorations in NCCLs. None has compared these clinical problems in NCCLs with and without occlusal wear facets. The present study sets out to determine the proportion of NCCLs that presents occlusal wear facets, and to compare the failure pattern of resin composite restorations in NCCLs with and without occlusal wear facets. Teeth with NCCLs were classified into two groups, those with and without occlusal wear facets. Both groups were restored using micro hybrid resin composite. The restorations were evaluated at the end of 2 years concerning post-operative sensitivity, retention, marginal integrity, marginal discolouration, wear, and secondary caries, using the USPHS criteria. Statistical analysis compared the ratings of each criterion between the two groups using Pearson's χ(2) or Fisher's exact test. About one-third (33.8%) of teeth with NCCLs presented with occlusal wear facets, more NCCLs with occlusal wear facets in mandibular teeth (44.7%) than maxillary teeth (24.5%). Retention rate of composite resin restorations in NCCLs with and without occlusal wear facets was 63.9% and 74.4% respectively at the end of 2 years. More marginal discolouration and defects were observed in restorations in NCCLs with occlusal wear facets, the differences were not statistically significant (p>0.05). The decline in ratings of marginal discolouration and defects, and the lower retention rate of restorations in NCCLs with occlusal wear facets may support the role of occlusal stress and tooth flexure as a cause of failure of restorations in NCCLs. The ability to distinguish between stress induced lesions (with occlusal wear facets) and other cervical lesions will have important ramifications for the success of their restorations because they are not subjected to the same physical forces that are responsible for the deterioration of the restoration. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Operation-Oriented Studies on Wear Properties of Surface-Hardened Alloy Cast Steels Used in Mining in the Conditions of the Combined Action of Dynamic Forces and an Abrasive Material

    Directory of Open Access Journals (Sweden)

    Wieczorek A.N.


    Full Text Available This paper presents the results of wear tests of shot-peened and not shot-peened cast steels used in the mining machinery industry, in particular in the construction of chain drums for armoured face conveyors. Wear tests were carried out in the conditions corresponding to the real operating conditions of armoured face conveyors during drifting work in rocks such as sandstone. The operating factors subjected to the analyses included the presence of quartz abrasive and the impact of external dynamic forces. On the basis of the wear tests as well as the microhardness and microstructure examinations performed, it has been found that the action of an additional dynamic force has a synergistic impact on the process of abrasive wear in loose quartz abrasive. It has been further found that the value of abrasive wear of chain wheels operated in the conditions of a combined action of abrasive and a dynamic force depends on whether the area of mating of wheels with the chain was shot-peened or not before the wear tests – an increase in the abrasive wear was observed for the wheels made of cast steel subjected to shot peening in the area of mating with the chain. Lower resistance to abrasive wear of the cast steels subjected to shot peening before the wear tests could result from the formation of cracks in the surface layer caused by the action of shot.

  5. Development of counting system for wear measurements using Thin Layer Activation and the Wearing Apparatus

    Energy Technology Data Exchange (ETDEWEB)

    França, Michel de A.; Suita, Julio C.; Salgado, César M., E-mail:, E-mail:, E-mail: [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil)


    This paper focus on developing a counting system for the Wearing Apparatus, which is a device previously built to generate measurable wear on a given surface (Main Source) and to carry the fillings from it to a filter (second source). The Thin Layer Activation is a technique used to produce activity on one of the Wearing Apparatus' piece, this activity is proportional to the amount of material worn, or scrapped, from the piece's surface. Thus, by measuring the activity on those two points it is possible to measure the produced wear. The methodology used in this work is based on simulations through MCNP-X Code to nd the best specifications for shielding, solid angles, detectors dimensions and collimation for the Counting System. By simulating several scenarios, each one different from the other, and analyzing the results in the form of Counts Per Second, the ideal counting system's specifications and geometry to measure the activity in the Main Source and the Filter (second source) is chosen. After that, a set of previously activated stainless steel foils were used to reproduce the real experiments' conditions, this real experiment consists of using TLA and the Wearing Apparatus, the results demonstrate that the counting system and methodology are adequate for such experiments. (author)

  6. Knowledge, attitude and practice of tooth wear among adults in Bertam, Penang (United States)

    Abdullah, Nurfarhana Farah; Roslan, Husniyati; Noor, Siti Noor Fazliah Mohd


    Tooth wear is an oral lesion with multifactorial causes. The prevalence is increasing with an increasing age. Knowledge of tooth wear is part of oral health and essential requirements are needed to modify health related behaviors. This study was aimed to determine the knowledge, attitude and practice of tooth wear and to compare with the socio-demographic factors. A cross-sectional study using a modified version of self-administered questionnaire was distributed among 390 adults (aged more than 18 years old) from three government institutions in Bertam, Penang. A total of 349 (89.5%) subjects had participated in this study with 55.3% were males and majority of the subjects were Malays. About 58.2% had low level of knowledge with mean score at 20.8. Meanwhile, 93.4% subjects had a positive attitude and 84.2% had poor level of practice on oral hygiene. The low mean score of knowledge among subjects was not necessary an indicator that attitude and practice were affected. However, identification of etiological factors emphasizes on educational approaches, and empowerment of patients and community towards awareness are the most important factors for preventive strategies.

  7. A Study on Wear Resistance of HVOF-Sprayed Ni-MoS2 Self-Lubricating Composite Coatings (United States)

    Liu, Y. L.; Jeng, M. C.; Hwang, J. R.; Chang, C. H.


    Composite coating techniques are becoming increasingly popular owing to their peculiar performances. In this study, the wear resistance of thermally sprayed Ni-MoS2 composite coatings on an AISI 1020 steel substrate was investigated. Ni-MoS2 composite powder (size: 60-90 μm) containing 25 wt.% of dispersed MoS2 was prepared by electroless plating. Ni-MoS2 composite coatings were then prepared by HVOF thermal spraying. The coatings were characterized by structural, surface morphological, and compositional analyses by means of microhardness tests, SEM/EDS, XRD, and ICP-AES. For the evaluation of their anti-wear properties, the composites were subjected to ball-on-disk dry wear tests based on the ASTM G99 standard at room temperature. Experimental results showed that some of the MoS2 content dispersed in the Ni-based composite coating burnt away during the high-temperature spraying process, thereby reducing the MoS2 concentration in the coating. In the wear test, the weight loss in the Ni-MoS2 composite coating was minimal under a low load (30 N). The average wear rate of the coatings was found to be ~1/40 times that of a Ni coating, showing that the wear resistance of the composite coatings was significantly improved by MoS2 addition.

  8. Structurally Integrated Coatings for Wear and Corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Beardsley, M. Brad; Sebright, Jason L.


    Wear and corrosion of structures cuts across industries and continues to challenge materials scientists and engineers to develop cost effective solutions. Industries typically seek mature technologies that can be implemented for production with rapid or minimal development and have little appetite for the longer-term materials research and development required to solve complex problems. The collaborative work performed in this project addressed the complexity of this problem in a multi-year program that industries would be reluctant to undertake without government partnership. This effort built upon the prior development of Advanced Abrasion Resistant Materials conduct by Caterpillar Inc. under DOE Cooperative Agreement No. DE-FC26-01NT41054. In this referenced work, coatings were developed that exhibited significant wear life improvements over standard carburized heat treated steel in abrasive wear applications. The technology used in this referenced work, arc lamp fusing of thermal spray coatings, was one of the primary technical paths in this work effort. In addition to extending the capability of the coating technology to address corrosion issues, additional competitive coating technologies were evaluated to insure that the best technology was developed to meet the goals of the program. From this, plasma transferred arc (PTA) welding was selected as the second primary technology that was investigated. Specifically, this project developed improved, cost effective surfacing materials and processes for wear and corrosion resistance in both sliding and abrasive wear applications. Materials with wear and corrosion performance improvements that are 4 to 5 times greater than heat treated steels were developed. The materials developed were based on low cost material systems utilizing ferrous substrates and stainless steel type matrix with hard particulates formed from borides and carbides. Affordability was assessed against other competing hard surfacing or coating

  9. Association of dietary habits and parental-reported sleep tooth grinding with tooth wear in children with mixed dentition. (United States)

    Restrepo, Claudia; Manfredini, Daniele; Manrique, Ruben; Lobbezoo, Frank


    Tooth wear has a multifactorial etiology, thus it should be assessed within a multiple-variable framework. The objective of this investigation was to assess the association of dietary habits and parental-reported sleep tooth grinding (STG) with tooth wear in children with mixed dentition. One hundred twenty-one (N = 121) subjects (mean age 9.6 years) participated in a cross-sectional study. Wear of 1637 teeth was evaluated using the screening module of the Tooth Wear Evaluation System (TWES). Parental-report of STG was evaluated by means of the Children's Sleep Habits Questionnaire (CSHQ), whilst dietary habits were investigated by means of the Health Behaviour in School-Aged Children Food-Frequency Questionnaire (HBSC-FFQ). Data were analyzed with the Spearman correlation test and ordinal-multiple-variable regression analyses. Odds Ratio (OR) and ordinal OR were obtained for the independent variables included in the models. Parental-report of STG is not associated with tooth wear in the mixed dentition; some dietary habits were found to be correlated with specific tooth wear patterns, but the correlation values were weak. Associations were found between dietary habits and the increase-to-increase severity of occlusal/incisal and non-occlusal/non-incisal tooth wear of some teeth (OR > 2). A strong correlation of dietary habits and sleep tooth grinding with tooth wear in the mixed dentition was not demonstrated. However, dietary habits showed to have effects in terms of increase-to-increase severity.

  10. Evaluation of surface water characteristics of novel daily disposable contact lens materials, using refractive index shifts after wear (United States)

    Schafer, Jeffery; Steffen, Robert; Reindel, William; Chinn, Joseph


    Purpose Contact lens wearers today spend much time using digital display devices. Contact lens manufacturers are challenged to develop products that account for longer periods of time where blink rate is reduced and tear-film evaporation rate is increased, affecting both visual acuity and comfort. Two manufacturers recently introduced novel daily disposable contact lenses with high surface water content. The objective of the present study was to compare surface water characteristics before and after initial wear of recently introduced nesofilcon A and delefilcon A high surface water lenses with those of etafilcon A lenses. Patients and methods Twenty healthy subjects wore each of the three lens types studied in a randomly determined order for 15 minutes. After each wearing, lenses were removed and the surface refractive index (RI) of each lens was immediately measured. Results The mean RI of the unworn delefilcon A lens was 1.34, consistent with water content in excess of 80%. After 15 minutes of wear, the surface RI shifted to 1.43, consistent with its reported 33% bulk water content. In contrast, the mean surface RI of the nesofilcon A lens was 1.38, both initially and after 15 minutes of wear, and that of the etafilcon A lens was 1.41 initially and 1.42 after 15 minutes of wear. Conclusion The surface of the delefilcon A lens behaves like a high water hydrogel upon insertion but quickly dehydrates to behave like its low-water silicone-hydrogel bulk material with respect to surface water content during wear, while both nesofilcon A and etafilcon A lenses maintain their water content during initial wear. The nesofilcon A lens appears unique among high water lenses in maintaining high surface and bulk water content during wear. This is important because changes in surface RI due to dehydration are reported to lead to visual aberration affecting user experience. PMID:26543349

  11. A study on the in-vitro wear of the natural tooth structure by opposing zirconia or dental porcelain (United States)

    Jung, Yu-Seok; Lee, Jae-Whang; Choi, Yeon-Jo; Ahn, Jin-Soo; Shin, Sang-Wan


    PURPOSE This study was conducted to evaluate clinical validity of a zirconia full-coverage crown by comparing zirconia's wear capacity over antagonistic teeth with that of feldspathic dental porcelain. MATERIALS AND METHODS The subject groups were divided into three groups: the polished feldspathic dental porcelain group (Group 1), the polished zirconia group (Group 2), and the polished zirconia with glazing group (Group 3). Twenty specimens were prepared from each group. Each procedure such as plasticity, condensation, and glazing was conducted according to the manufacturer's manual. A wear test was conducted with 240,000 chewing cycles using a dual-axis chewing simulator. The degree of wear of the antagonistic teeth was calculated by measuring the volume loss using a three-dimensional profiling system and ANSUR 3D software. The statistical significance of the measured degree of wear was tested with a significant level of 5% using one-way ANOVA and the Tukey test. RESULTS The degrees of wear of the antagonistic teeth were 0.119 ± 0.059 mm3 in Group 1, 0.078 ± 0.063 mm3 in Group 3, and 0.031 ± 0.033 mm3 in Group 2. Statistical significance was found between Group 1 and Groups 2 and between Group 2 and 3, whereas no statistical significance was found between Group 1 and Group 3. CONCLUSION Despite the limitations of this study on the evaluation of antagonistic teeth wear, the degree of antagonistic tooth wear was less in zirconia than feldspathic dental porcelain, representing that the zirconia may be more beneficial in terms of antagonistic tooth wear. PMID:21165280

  12. Comparison between PEEK and Ti6Al4V concerning micro-scale abrasion wear on dental applications. (United States)

    Sampaio, M; Buciumeanu, M; Henriques, B; Silva, F S; Souza, J C M; Gomes, J R


    In the oral cavity, abrasive wear is predictable at exposed tooth or restorative surfaces, during mastication and tooth brushing. Also, wear can occur at contacting surfaces between the Ti-based prosthetic structures and implants in presence of abrasive compounds from food or toothpaste. Thus, the aim of this work was to compare the abrasive wear resistance of PEEK and Ti6Al4V on three-body abrasion related to different hydrated silica content and loads. Surfaces of Ti6Al4V or PEEK cylinders (8mm diameter and 4mm height) were wet ground on SiC papers and then polished with 1µm diamond paste. After that, surfaces were ultrasonically cleaned in propyl alcohol for 15min and then in distilled water for 10min. Micro-scale abrasion tests were performed at 60rpm and on different normal loads (0.4, 0.8 or 1.2N) after 600 ball revolutions using suspensions with different weight contents of hydrated silica. After abrasive tests, wear scars on flat samples were measured to quantify the wear volume and characterized by scanning electron microscope (SEM) to identify the dominant wear mechanisms. Results showed a higher volume loss rate on PEEK than that recorded on Ti6Al4V,, when subjected to three-body abrasion tests involving hydrated silica suspensions. An increase in volume loss was noted on both tested materials when the abrasive content or load was increased. PEEK was characterized by less wear resistance than that on Ti6Al4V after micro-scale abrasion wear in contact with hydrated silica particles, as commonly found in toothpastes. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. The JCMT Gould Belt Survey: a quantitative comparison between SCUBA-2 data reduction methods


    Mairs, S.; Johnstone, D.; Kirk, H; Graves, S.; Buckle, J.; Beaulieu, S. F.; Berry, D. S.; Broekhoven-Fiene, H.; Currie, M. J.; Fich, M.; Hatchell, J.; Jenness, T.; Mottram, J. C.; Nutter, D.; Pattle, K.


    Performing ground-based submillimetre observations is a difficult task as the measurements are subject to absorption and emission from water vapour in the Earth's atmosphere and time variation in weather and instrument stability. Removing these features and other artefacts from the data is a vital process which affects the characteristics of the recovered astronomical structure we seek to study. In this paper, we explore two data reduction methods for data taken with the Submillimetre Common-...

  14. The short-term effects of PMMA and RGP contact lens wear on keratometric behaviour: a pilot study*

    Directory of Open Access Journals (Sweden)

    E. Chetty


    Full Text Available This article represents the preliminary findings of a larger study that included 24 subjects that were equally divided into three groups, namely, the PMMA (polymethyl methacrylate group, the RGP(rigid gas permeable group and the control group. The aim of this study was to establish the short term effects (if any of PMMA and RGP contact lens wear on keratometric behaviour. A controlsubject was also included in the study to establish a reference fornormal diurnal changes in keratometric behaviour. Fifty successive auto-keratometric measurements were taken before and immediately after three hours of rigid contact lens wear for the first subject in the PMMA group and the first subject in the RGP group (experimental samples. Fifty successive auto-keratometric measurements were also taken on the first subject of the control group before and immediately after three hours of no lens wear (control sample. Data collected were analysed using multivariate statistical methods that in the past have been used infrequently in this area of study. This investigation revealed that, at least in these two randomly selected subjects, rigid contact lens wear appears to  influence keratometric behaviour (PMMA contact lenses more so than RGP contact lenses. (S Afr Optom 2010 69(4 173-181

  15. Comparative clinical performance of rigid versus soft hyper Dk contact lenses used for continuous wear. (United States)

    Maldonado-Codina, Carole; Morgan, Philip B; Efron, Nathan; Efron, Suzanne


    The purpose of this study is to investigate the comparative clinical performance of two hyper Dk contact lenses: a silicone hydrogel lens (Focus Night & Day, Ciba Vision) and a rigid lens (Z-alpha, Menicon Co. Ltd.) when worn for up to 30 days of continuous wear (CW). The rigid lens was worn on an unplanned replacement basis, whereas the soft lens was replaced monthly. One hundred subjects were recruited. Fifty neophyte subjects were randomly assigned into one of the lens types (25 subjects per lens type). Twenty-five existing daily wear (DW) rigid lens users wore the rigid study lens and 25 existing DW soft lens users wore the soft study lens. Visual acuity, lens fit, keratometry, refraction, lens surface assessment, physiological response, and subjective response were investigated at baseline and after 1 week of DW and 24 hours, 1 week, and 1, 3, 6, 9, and 12 months of CW. Analysis compared lens type (rigid vs. soft) and subject group (experienced vs. neophyte). Sixty-eight subjects completed the study. Visual acuity was similar for the two lens types and subject groups. Lens fit was judged to be adequate in all subjects. Corneal curvature of subjects in the rigid groups became flatter by 0.13 mm compared with 0.04 mm for subjects in the soft lens groups (F = 14.7, p = 0.0003); the refractive findings mirrored these corneal changes. The increasing rate of deposition on rigid lenses was consistent with the fact that these lenses were not replaced during the study. Conjunctival hyperemia and staining were similar for the two lens types but greater among experienced wearers at baseline (F = 13.8, p = 0.0005; F = 5.3, p = 0.02, respectively). Corneal staining was higher for the rigid lens wearers (F = 5.6, p = 0.02) but this was mainly the result of the initial higher scores in the rigid lens experienced group. The change in papillary conjunctivitis was greater for subjects in the soft lens groups than rigid lens groups (F = 4.6, p = 0.04). Comfort was initially

  16. Dry Rolling Friction and Wear of Elastomer Systems and Their Finite Element Modelling


    Xu, Dan


    Elastomers and their various composites, and blends are frequently used as engineering working parts subjected to rolling friction movements. This fact already substantiates the importance of a study addressing the rolling tribological properties of elastomers and their compounds. It is worth noting that until now the research and development works on the friction and wear of rubber materials were mostly focused on abrasion and to lesser extent on sliding type of loading. As the tribological ...

  17. Influence of wearing an unstable shoe construction on compensatory control of posture


    Sousa, Andreia S. P.; Macedo, Rui; Santos, Rubim; Tavares, João Manuel


    This study investigated the influence of wearing unstable shoe construction (WUS) on compensatory postural adjustments (CPA) associated with external perturbations. Thirty-two subjects stood on a force platform resisting an anterior-posterior horizontal force applied to a pelvic belt via a cable, which was suddenly released. They stood under two conditions: barefoot and WUS. The electromyographic (EMG) activity of gastrocnemius medialis, tibialis anterior, rectus femoris,...

  18. Repeatability of corneal biomechanical measurements in children wearing spectacles and orthokeratology lenses. (United States)

    Hon, Ying; Cheung, Sin W; Cho, Pauline; Lam, Andrew K C


    To determine the repeatability of corneal hysteresis (CH) and corneal resistance factor (CRF) measurements in children wearing spectacles and children under orthokeratology (ortho-k) therapy using the Ocular Response Analyzer (ORA). CH and CRF were measured twice at a 10-min interval using ORA on the same day in both eyes of 25 children (mean age = 10.6 ± 1.2 years) wearing spectacles and 34 children (mean age = 10.9 ± 1.0 years) wearing ortho-k lenses. Four measurements were obtained from each eye in each set of measurements. Only data from the right eyes were analyzed. No significant between-measurement differences in CH and CRF were found in either group of subjects (paired t-tests, p > 0.05) and no correlations were found between the mean differences and their means (Pearson's correlations, -0.09 spectacle and ortho-k groups, respectively. A significant between-group difference in CRF was found (unpaired t-tests, p = 0.02). Repeatability of CH and CRF measurements using the ORA is within ± 2 mmHg in children wearing spectacles or ortho-k lenses. We suggest that the ORA can be used to monitor long-term corneal biomechanical changes during ortho-k treatment. Ophthalmic & Physiological Optics © 2012 The College of Optometrists.

  19. Effect of thermo-mechanical loading on marginal quality and wear of primary molar crowns. (United States)

    Krämer, N; Rudolph, H; Garcia-Godoy, F; Frankenberger, R


    To evaluate the effect of thermo-mechanical loading (TML) on marginal quality and wear of different crown types for primary molars. Eighty extracted human primary molars were used. After preparation, five groups received different crowns (n=16): preformed metal crowns (3M ESPE) and NuSmile crowns (Orthodontic Technologies Inc.) were inserted as preformed metal crowns; as semi-preformed crowns Protemp crowns (3M ESPE) were luted; and as individually manufactured resin composite crowns Filtek Z250 (3M ESPE) and Heliomolar (Ivoclar Vivadent) were used. Specimens were subjected to 2,500 thermal cycles between 5-55(o)C and chewing simulation for 100,000 cycles at 50N at a frequency of 0.5 Hz. Before and after thermo-mechanical loading, impressions of the teeth were taken and replicas were made. The replicas received marginal quality evaluation under a SEM at x200 magnification. Occlusal wear was measured as vertical height loss using a 3-D laser scanning microscope. After TML, all crowns were intact. The adhesively bonded crowns showed significantly better marginal quality to dentine/cementum compared with GIC luted crowns (pcrowns showed a good fit and nearly transition-free margins also after TML. Preformed metal crowns showed the significantly lowest wear rates compared to the resin composites (pcrown types under investigation showed a good performance concerning the evaluated parameters marginal quality and wear.

  20. Effect of low temperature annealing on the wear properties of NITINOL (United States)

    Mukunda, Sriram; Nath. S, Narendra; Herbert, Mervin A.; Mukunda, P. G.


    NiTi shape memory alloy is a wonder material that is a solution looking for problems. The material finds wide biomedical applications like endodontic files for root canal treatment and cardiovascular stents. This material has rendered the surgical procedure simple compared to that with the existing Stainless Steel (SS) or titanium ones. NiTi as an endodontic file would cause less discomfort to the patients in comparison to that with far stiffer SS or titanium ones. Here nearly equi-atomic 50:50 commercial NiTi rods were subjected to low temperature aging at 300 to 450°C. The wear resistance of the as-received and the heat-treated samples was studied using adhesive wear tests on hardened steel counter face. Abrasive wear tests were run against Alumina disc to simulate the working of endodontic drills and files against dental hard and soft tissues. The abrasive wear resistance is expected to be proportional to the Vickers Hardness of the material and is high for the 450°C heat-treated sample. A correlation between the mechanical properties and microstructures of this material is attempted

  1. Level of compliance in contact lens wearing medical doctors in Nepal. (United States)

    Sapkota, Kishor


    To determine the level of compliance and major non-compliant behaviors in contact lens (CL) wearing medical doctors (MDs) and to compare it with age matched CL wearing normal subjects with no medical background (NS). Thirty-nine current CL wearing MDs, who were prescribed CLs in Nepal Eye Hospital, Kathmandu, Nepal, between 2007 and 2011, were interviewed on ten modifiable compliant behaviors regarding lens care and maintenance. The level of compliance and the rate of non-compliance for each behavior were determined and compared with NS. Level of compliance was good, average and poor in 35.9%, 48.7% and 15.4% of MDs, respectively. There was no significant difference in compliance between MDs and NS (p=0.209). Level of compliance was not associated with age, gender and duration of lens wear (p>0.05). Compliance rate varied according to different behaviors, achieving a good compliance level of 95% for hand hygiene, avoidance of water contact and not sleeping with lenses. There was poor compliance for topping up solution (53.8%) and lens case replacement (15.4%). About one third of MDs had a good level of compliance. Level of compliance and compliance rate of different behaviors were similar in MDs and NS. Periodic lens case replacement was the most neglected behavior in CL wearers for this region. Copyright © 2015 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  2. Microstructure and Wear Analysis of FeBCr Based Coating Deposited by HVOF Method

    Directory of Open Access Journals (Sweden)

    M.S. Priyan


    Full Text Available Thermally sprayed coatings that are based on FeBCr-related alloy powders are widely used to improve properties such as the surface hardness and wear resistance of a variety of coated metal substrate materials. Gray cast iron is widely used in the automobile industry due to its low cost and performance. In this work Gray cast iron substrate is coated with FeBCr alloy powder to improve its performance. The microstructure and micro abrasive wear performance of both the uncoated substrates and the coated substrates were characterized by optical microscopy as well as by Scanning Electron Microscope (SEM. In addition, X-ray Diffraction (XRD was undertaken in the partial characterization of the coating. The densely layered coating had porosity levels that were below 2.5 % and a high surface hardness, of the order of 980 HV0.1. The coating exhibited excellent wear resistance when subjected to the ball-cratering test method. The low coefficients of friction of hard coating on the substrate were recorded. The wear performance of the coating was nearly 82 % better than that of the substrate, with a 0.05 N load, even under severe three body abrasive conditions.

  3. Wear and repair of stainless steel crowns. (United States)

    Yilmaz, Y; Kara, N Belduz; Yilmaz, A; Sahin, H


    The purpose of this study was to determine the wear of stainless steel crowns (SSCs) in children, and compare the extent of microleakage in SSCs that had been repaired using either a cermet glass-ionomer cement (GIC) or a packable composite resin (CR). For the first aim, the occlusal surface thickness of 31 harvested SSCs (21 primary first and 10 second molars) and 18 unused SSCs was measured, and then examined under scanning electron microscopy. For the second aim, standardised holes were prepared on the occlusal surfaces of 20 SSCs, and then repaired using either a cermet GIC or packable CR. After their repair, the extent of microleakage was determined using 0.5% basic fuchsin and stereomicroscopy. The thickness of all the harvested SCCs was 5.3 μm less than that of the unused SCCs (p<0.02), and there were no significant differences between the thickness and occlusal wear rates of harvested SSCs from the first and second primary molars. Although neither of the two repair materials completely prevented microleakage, the number of specimens in which microleakage occurred after repair with a cermet GIC was significantly lower than the number of specimens in which a packable CR was used (p<0.05). We concluded that the occlusal surfaces of SSCs for first and second primary molars display wear. Although perforated SSCs can be repaired using either a cermet GIC or a packable CR, less microleakage occurs in SSCs that were repaired with a cermet GIC than those with a packable CR.

  4. Acanthamoeba keratitis and contact lens wear. (United States)

    Lindsay, Richard G; Watters, Grant; Johnson, Richard; Ormonde, Susan E; Snibson, Grant R


    Acanthamoeba keratitis is a rare but serious complication of contact lens wear that may cause severe visual loss. The clinical picture is usually characterised by severe pain, sometimes disproportionate to the signs, with an early superficial keratitis that is often misdiagnosed as herpes simplex virus (HSV) keratitis. Advanced stages of the infection are usually characterised by central corneal epithelial loss and marked stromal opacification with subsequent loss of vision. In this paper, six cases of contact lens-related Acanthamoeba keratitis that occurred in Australia and New Zealand over a three-year period are described. Three of the patients were disposable soft lens wearers, two were hybrid lens wearers and one was a rigid gas permeable lens wearer. For all six cases, the risk factors for Acanthamoeba keratitis were contact lens wear with inappropriate or ineffective lens maintenance and exposure of the contact lenses to tap or other sources of water. All six patients responded well to medical therapy that involved topical use of appropriate therapeutic agents, most commonly polyhexamethylene biguanide and propamidine isethionate, although two of the patients also subsequently underwent deep lamellar keratoplasty due to residual corneal surface irregularity and stromal scarring. Despite the significant advances that have been made in the medical therapy of Acanthamoeba keratitis over the past 10 years, prevention remains the best treatment and patients who wear contact lenses must be thoroughly educated about the proper use and care of the lenses. In particular, exposure of the contact lenses to tap water or other sources of water should be avoided.

  5. The SCUBA-2 Ambitious Sky Survey: a catalogue of beam-sized sources in the Galactic longitude range 120°-140° (United States)

    Nettke, Will; Scott, Douglas; Gibb, Andy G.; Thompson, Mark; Chrysostomou, Antonio; Evans, A.; Hill, Tracey; Jenness, Tim; Joncas, Gilles; Moore, Toby; Serjeant, Stephen; Urquhart, James; Vaccari, Mattia; Weferling, Bernd; White, Glenn; Zhu, Ming


    The SCUBA-2 Ambitious Sky Survey (SASSy) is composed of shallow 850-μm imaging using the Submillimetre Common-User Bolometer Array 2 (SCUBA-2) on the James Clerk Maxwell Telescope. Here we describe the extraction of a catalogue of beam-sized sources from a roughly 120 deg2 region of the Galactic plane mapped uniformly (to an rms level of about 40 mJy), covering longitude 120° extraction procedure through estimates of the false discovery rate, as well as by adding artificial sources to the real images. The primary catalogue contains a total of 189 sources at 850 μm, down to an S/N threshold of approximately 4.6. Additionally, we list 136 sources detected down to S/N = 4.3, but recognize that as we go lower in S/N, the reliability of the catalogue rapidly diminishes. We perform follow-up observations of some of our lower significance sources through small targeted SCUBA-2 images and list 265 sources detected in these maps down to S/N = 5. This illustrates the real power of SASSy: inspecting the shallow maps for regions of 850-μm emission and then using deeper targeted images to efficiently find fainter sources. We also perform a comparison of the SASSy sources with the Planck Catalogue of Compact Sources and the IRAS Point Source Catalogue, to determine which sources discovered in this field might be new, and hence potentially cold regions at an early stage of star formation.

  6. Characterization of the wear resistant aluminum oxide - 40% titaniumdioxide coating

    Directory of Open Access Journals (Sweden)

    Mihailo R. Mrdak


    Full Text Available Plasma spray coatings play an important role in the design of surface properties of engineering components in order to increase their durability and performance under different operating conditions. Coatings are the most often used for wear resistance. This paper presents the microstructure and mechanical properties Al2O3_­40wt.%TiO2 coating resistant to dry friction slide, grain abrasion and erosion of particles at operating temperatures up to 540°C. In order to obtain the optimal characteristics of coating was performed  optimization  of deposition parameters. The powder Al2O3­40wt.%TiO2 is deposited atmospheric plasma spraying (APS process with a plasma current of 700, 800 and 900A. Evaluate the quality of the coating Al2O3­40wt.%TiO2 were made on the basis of their hardness, tensile bond strength and microstructure. The best performance showed the deposited layers with 900A. The morphology of the powder particles Al2O3­40wt.%TiO2 was examined with SEM (Scanning Electron Microscope. Microstructure of the coatings was examined by light microscopy. Analysis of the deposited layers was performed in accordance with standard Pratt & Whitney. Evaluation of mechanical properties of the layers was done by examining HV0.3 microhardness and tensile strength of the tensile testing. Studies have shown that plasma currents significantly affects the mechanical properties and microstructure of coatings which are of crucial importance for the protection for components subjected to wear       

  7. Wear testing of total hip replacements under severe conditions. (United States)

    Zietz, Carmen; Fabry, Christian; Reinders, Joern; Dammer, Rebecca; Kretzer, Jan Philippe; Bader, Rainer; Sonntag, Robert


    Controlled wear testing of total hip replacements in hip joint simulators is a well-established and powerful method, giving an extensive prediction of the long-term clinical performance. To understand the wear behavior of a bearing and its limits under in vivo conditions, testing scenarios should be designed as physiologically as possible. Currently, the ISO standard protocol 14242 is the most common preclinical testing procedure for total hip replacements, based on a simplified gait cycle for normal walking conditions. However, in recent years, wear patterns have increasingly been observed on retrievals that cannot be replicated by the current standard. The purpose of this study is to review the severe testing conditions that enable the generation of clinically relevant wear rates and phenomena. These conditions include changes in loading and activity, third-body wear, surface topography, edge wear and the role of aging of the bearing materials.

  8. Effect of wearing a swimsuit on hydrodynamic drag of swimmer

    Directory of Open Access Journals (Sweden)

    Daniel Almeida Marinho


    Full Text Available The purpose of this study was to analyse the effect of wearing a swimsuit on swimmer's passive drag. A computational fluid dynamics analysis was carried out to determine the hydrodynamic drag of a female swimmer's model (i wearing a standard swimsuit; (ii wearing a last generation swimsuit and; (iii with no swimsuit, wearing light underwear. The three-dimensional surface geometry of a female swimmer's model with different swimsuit/underwear was acquired through standard commercial laser scanner. Passive drag force and drag coefficient were computed with the swimmer in a prone position. Higher hydrodynamic drag values were determined when the swimmer was with no swimsuit in comparison with the situation when the swimmer was wearing a swimsuit. The last generation swimsuit presented lower hydrodynamic drag values, although very similar to standard swimsuit. In conclusion, wearing a swimsuit could positively influence the swimmer's hydrodynamics, especially reducing the pressure drag component.

  9. Correlation between Wear Resistance and Lifetime of Electrical Contacts

    Directory of Open Access Journals (Sweden)

    Jian Song


    Full Text Available Electrical contacts are usually plated in order to prevent corrosion. Platings of detachable electrical contacts experience wear because of the motion between contacts. Once the protecting platings have been worn out, electrical contacts will fail rapidly due to corrosion or fretting corrosion. Therefore the wear resistance of the platings is a very important parameter for the long lifetime of electrical contacts. Many measures which improve the wear resistance can diminish the conductivity of the platings. Due to the fact that platings of electrical contacts must have both a high wear resistance and a high electrical conductivity, the manufacturing of high performance platings of electrical contacts poses a great challenge. Our study shows firstly the correlation between the wear resistance of platings and lifetime of electrical contacts and then the measures, which improve the wear resistance without impairing the electrical performance of the contacts.

  10. Control of erosive tooth wear: possibilities and rationale

    Directory of Open Access Journals (Sweden)

    Mônica Campos Serra


    Full Text Available Dental erosion is a type of wear caused by non bacterial acids or chelation. There is evidence of a significant increase in the prevalence of dental wear in the deciduous and permanent teeth as a consequence of the frequent intake of acidic foods and drinks, or due to gastric acid which may reach the oral cavity following reflux or vomiting episodes. The presence of acids is a prerequisite for dental erosion, but the erosive wear is complex and depends on the interaction of biological, chemical and behavioral factors. Even though erosion may be defined or described as an isolated process, in clinical situations other wear phenomena are expected to occur concomitantly, such as abrasive wear (which occurs, e.g, due to tooth brushing or mastication. In order to control dental loss due to erosive wear it is crucial to take into account its multifactorial nature, which predisposes some individuals to the condition.

  11. Tool Wear Feature Extraction Based on Hilbert Marginal Spectrum (United States)

    Guan, Shan; Song, Weijie; Pang, Hongyang


    In the metal cutting process, the signal contains a wealth of tool wear state information. A tool wear signal’s analysis and feature extraction method based on Hilbert marginal spectrum is proposed. Firstly, the tool wear signal was decomposed by empirical mode decomposition algorithm and the intrinsic mode functions including the main information were screened out by the correlation coefficient and the variance contribution rate. Secondly, Hilbert transform was performed on the main intrinsic mode functions. Hilbert time-frequency spectrum and Hilbert marginal spectrum were obtained by Hilbert transform. Finally, Amplitude domain indexes were extracted on the basis of the Hilbert marginal spectrum and they structured recognition feature vector of tool wear state. The research results show that the extracted features can effectively characterize the different wear state of the tool, which provides a basis for monitoring tool wear condition.

  12. Tribocorrosion wear of austenitic and martensitic steels

    Directory of Open Access Journals (Sweden)

    G. Rozing


    Full Text Available This paper explores the impact of tribocorrosion wear caused by an aggressive acidic media. Tests were conducted on samples made of stainless steel AISI 316L, 304L and 440C. Austenitic steels were tested in their nitrided state and martensitic in quenched and tempered and then induction hardened state. Electrochemical corrosion resistance testing and analysis of the microstructure and hardness in the cross section was carried out on samples of selected steels. To test the possibility of applying surface modification of selected materials in conditions of use, tests were conducted on samples/parts in a worm press for final pressing.

  13. The corneal stroma during contact lens wear. (United States)

    Jalbert, Isabelle; Stapleton, Fiona


    Recent technological advances have lead to novel descriptions of the microanatomy of the corneal stroma. In the first section of this review, these findings and the role they play in the maintenance of vital properties such as corneal transparency, mechanical strength, homeostasis, wound-healing response and metabolism are described. In the second part, contact lens induced stromal alterations such as acidosis, oedema, striae, thinning and opacities are reviewed as well as the more recently described phenomenon of microdot deposits and keratocyte loss with an emphasis on how lens wearing stromal effects can be minimised.

  14. Aging mourning doves by outer primary wear (United States)

    Wight, H.M.; Blankenship, L.H.; Tomlinson, R.E.


    Many immature mourning doves (Zenaidura macroura) cannot be aged by the conventional white-tipped primary covert method if molt has proceeded beyond the 7th primary. A new method of aging doves in this group is based on the presence (immature) or absence (adult) of a buff-colored fringe on the tips of the 9th and 10th primaries. Experienced biologists were nearly 100 percent accurate in aging wings of 100 known-age doves from eastern and midwestern states. The technique is not as reliable for doves from southwestern United States because of added feather wear, apparently from harsh vegetative and soil conditions.

  15. The SCUBA-2 Cosmology Legacy Survey: the nature of bright submm galaxies from 2 deg2 of 850-μm imaging (United States)

    Michałowski, Michał J.; Dunlop, J. S.; Koprowski, M. P.; Cirasuolo, M.; Geach, J. E.; Bowler, R. A. A.; Mortlock, A.; Caputi, K. I.; Aretxaga, I.; Arumugam, V.; Chen, Chian-Chou; McLure, R. J.; Birkinshaw, M.; Bourne, N.; Farrah, D.; Ibar, E.; van der Werf, P.; Zemcov, M.


    We present physical properties [redshifts (z), star-formation rates (SFRs) and stellar masses ({M_star})] of bright (S850 ≥ 4 mJy) submm galaxies in the ≃2 deg2 COSMOS and UDS fields selected with SCUBA-2/JCMT. We complete the galaxy identification process for all (≃2000) S/N ≥ 3.5 850-μm sources, but focus our scientific analysis on a high-quality subsample of 651 S/N ≥ 4 sources with complete multiwavelength coverage including 1.1-mm imaging. We check the reliability of our identifications, and the robustness of the SCUBA-2 fluxes by revisiting the recent ALMA follow-up of 29 sources in our sample. Considering >4 mJy ALMA sources, our identification method has a completeness of ≃86 per cent with a reliability of ≃92 per cent, and only ≃15-20 per cent of sources are significantly affected by multiplicity (when a secondary component contributes >1/3 of the primary source flux). The impact of source blending on the 850-μm source counts as determined with SCUBA-2 is modest; scaling the single-dish fluxes by ≃0.9 reproduces the ALMA source counts. For our final SCUBA-2 sample, we find median z = 2.40^{+0.10}_{-0.04}, SFR = 287 ± 6 M⊙ yr- 1 and log ({M_star}/{M_{⊙}}) = 11.12± 0.02 (the latter for 349/651 sources with optical identifications). These properties clearly locate bright submm galaxies on the high-mass end of the 'main sequence' of star-forming galaxies out to z ≃ 6, suggesting that major mergers are not a dominant driver of the high-redshift submm-selected population. Their number densities are also consistent with the evolving galaxy stellar mass function. Hence, the submm galaxy population is as expected, albeit reproducing the evolution of the main sequence of star-forming galaxies remains a challenge for theoretical models/simulations.


    Directory of Open Access Journals (Sweden)

    V. M. Ilyushenko


    Full Text Available The article presents the results of the tests on the wear resistance of chromium cast irons of different compositions obtained in sand forms. It has been shown that increase of the wear resistance and mechanical properties of the cast iron is possible to obtain using the casting in metal molds. A further increase in wear resistance of parts produced in metal molds is possible by changing the technological parameters of casting and alloying by titanium.

  17. Wearable Android Android wear and Google Fit app development

    CERN Document Server

    Mishra, Sanjay M


    Software Development/Mobile/Android/Wearable/Fitness Build ""Wearable"" Applications on the Android Wear and Google Fit Platforms This book covers wearable computing and wearable application development particularly for Android Wear (smartwatches) and Google Fit (fitness sensors). It provides relevant history, background and core concepts of wearable computing and ubiquitous computing, as a foundation for designing/developing applications for the Android Wear and Google Fit platforms. This book is intended for Android wearable enthusiasts, technologists and software developers. Gain ins

  18. Students Wearing Police Uniforms Exhibit Biased Attention toward Individuals Wearing Hoodies. (United States)

    Civile, Ciro; Obhi, Sukhvinder S


    Police provide an essential public service and they often operate in difficult circumstances, requiring high-speed cognition. Recent incidents involving apparent profiling and aggressive behavior have led to accusations that the police are sometimes biased. Given that previous research has shown a link between clothing and cognition, we investigated the question of whether the police uniform itself might induce a bias in social attention. To address this question, and using a Canadian university student sample, we assessed whether wearing a police uniform biases attention toward black faces compared to white faces, and low-status individuals compared to high-status individuals. In Experiment 1 ( n = 28), participants wore either a police-style uniform or mechanic overalls, and performed a shape categorization task in the presence of a distractor that could be either: a black face, a white face, a person wearing a hoodie (whom we propose will be associated with low SES), or a person wearing a suit (whom we propose will be associated with high SES). Participants wearing the police-style uniform exhibited biased attention, indexed by slower reaction times (RTs), in the presence of low-SES images. In Experiment 2 ( n = 28), we confirmed this bias using a modified Dot-Probe task - an alternate measure of attentional bias in which we observed faster RTs to a dot probe that was spatially aligned with a low SES image. Experiment 3 ( n = 56) demonstrated that attentional bias toward low-SES targets appears only when participants wear the police-style uniform, and not when they are simply exposed to it - by having it placed on the desk in front of them. Our results demonstrate that wearing a police-style uniform biases attention toward low-SES targets. Thus, wearing a police-style uniform may induce a kind of "status-profiling" in which individuals from low-status groups become salient and capture attention. We note that our results are limited to university students and

  19. Wear characteristics of a rheocast leaded aluminium metal - metal composite

    Energy Technology Data Exchange (ETDEWEB)

    Garg, R. (Roorkee Univ. (India). Dept. of Metallurgical Engineering); Mohan, S. (Banaras Hindu Univ., Varanasi (India). Dept. of Metallurgical Engineering); Agarwala, V. (Roorkee Univ. (India). Dept. of Metallurgical Engineering); Agarwala, R.C. (Roorkee Univ. (India). Dept. of Metallurgical Engineering)


    In Al-Pb alloys, boundary lubrication is provided by lead but the matrix with pure aluminium does not provide adequate strength at high loads and high sliding velocities. So in the present investigation an Al-Cu-Si alloy has been taken as the base material and lead has been incorporated by the rheocasting technique. Wear characteristics of the alloy have been investigated at different loads, sliding velocities and sliding distances. Bulk wear has been observed to increase almost linearly with applied load and sliding velocity, but with sliding distance the bulk wear shows a short period of running-in followed by a long steady-state wear. (orig.)

  20. Prediction of Cone Crusher Performance Considering Liner Wear

    Directory of Open Access Journals (Sweden)

    Yanjun Ma


    Full Text Available Cone crushers are used in the aggregates and mining industries to crush rock material. The pressure on cone crusher liners is the key factor that influences the hydraulic pressure, power draw and liner wear. In order to dynamically analyze and calculate cone crusher performance along with liner wear, a series of experiments are performed to obtain the crushed rock material samples from a crushing plant at different time intervals. In this study, piston die tests are carried out and a model relating compression coefficient, compression ratio and particle size distribution to a corresponding pressure is presented. On this basis, a new wear prediction model is proposed combining the empirical model for predicting liner wear with time parameter. A simple and practical model, based on the wear model and interparticle breakage, is presented for calculating compression ratio of each crushing zone along with liner wear. Furthermore, the size distribution of the product is calculated based on existing size reduction process model. A method of analysis of product size distribution and shape in the crushing process considering liner wear is proposed. Finally, the validity of the wear model is verified via testing. The result shows that there is a significant improvement of the prediction of cone crusher performance considering liner wear as compared to the previous model.

  1. Wear Behavior of an Unstable Knee: Stabilization via Implant Design?

    Directory of Open Access Journals (Sweden)

    Jörn Reinders


    Full Text Available Background. Wear-related failures and instabilities are frequent failure mechanisms of total knee replacements. High-conforming designs may provide additional stability for the joint. This study analyzes the effects of a ligamentous insufficiency on the stability and the wear behavior of a high-conforming knee design. Methods. Two simulator wear tests were performed on a high-conforming total knee replacement design. In the first, a ligamentous-stable knee replacement with a sacrificed anterior cruciate ligament was simulated. In the second, a ligamentous-unstable knee with additionally insufficient posterior cruciate ligament and medial collateral ligament was simulated. Wear was determined gravimetrically and wear particles were analyzed. Implant kinematics was recorded during simulation. Results. Significantly higher wear rates (P≤0.001 were observed for the unstable knee (14.58±0.56 mg/106 cycles compared to the stable knee (7.97 ± 0.87 mg/106 cycles. A higher number of wear particles with only small differences in wear particle characteristics were observed. Under unstable knee conditions, kinematics increased significantly for translations and rotations (P≤0.01. This increase was mainly attributed to higher tibial posterior translation and internal rotations. Conclusion. Higher kinematics under unstable test conditions is a result of insufficient stabilization via implant design. Due to the higher kinematics, increased wear was observed in this study.

  2. Friction and wear in polymer-based materials

    CERN Document Server

    Bely, V A; Petrokovets, M I


    Friction and Wear in Polymer-Based Materials discusses friction and wear problems in polymer-based materials. The book is organized into three parts. The chapters in Part I cover the basic laws of friction and wear in polymer-based materials. Topics covered include frictional interaction during metal-polymer contact and the influence of operating conditions on wear in polymers. The chapters in Part II discuss the structure and frictional properties of polymer-based materials; the mechanism of frictional transfer when a polymer comes into contact with polymers, metals, and other materials; and

  3. The hardness and sliding wear behaviour of a bainitic steel

    Energy Technology Data Exchange (ETDEWEB)

    Shipway, P.H. [Nottingham Univ. (United Kingdom). Dept. of Materials Engineering and Materials Design; Wood, S.J. [Nottingham Univ. (United Kingdom). Dept. of Materials Engineering and Materials Design; Dent, A.H. [Nottingham Univ. (United Kingdom). Dept. of Materials Engineering and Materials Design


    High-strength bainitic steels have a number of desirable mechanical properties and have thus been viewed as candidate materials for heavy wear applications. This work examines the role of transformation temperature on the wear resistance of isothermally formed bainite from a single alloy steel and compares it with wear resistance following other heat treatments such as quenching, quenching and tempering and normalisation. The sliding wear resistance was examined for a range of applied loads at a constant sliding velocity of 1 m s{sup -1}. Microstructural constituents of the steels were related to their wear resistance. The hardness of the bainitic steel was a function of the isothermal transformation temperature and its variation has been correlated with the transformation behaviour. However, the hardness of the materials did not correlate well with their wear resistance, with the hardest martensitic steel showing greater wear rates than the normalised steel. Bainitic microstructures formed at low transformation temperatures were found to have a high wear resistance which in many cases was a factor of two better than any of the other microstructures examined; this material had a good combination of hardness and toughness on the microstructural level due to the fine nature of the bainite formed with high dislocation density and the lack of embrittling martensite and cementite phases and it is proposed that these attributes confer its high wear resistance. (orig.)

  4. Polyethylene and metal wear particles: characteristics and biological effects. (United States)

    Catelas, Isabelle; Wimmer, Markus A; Utzschneider, Sandra


    This paper first presents a brief overview about the mechanism of wear particle formation as well as wear particle characteristics in metal-on-polyethylene and metal-on-metal artificial hip joints. The biological effects of such particles are then described, focusing on the inflammatory response induced by each type of particles as well as on how metal wear products may be the source of a T lymphocyte-mediated specific immune response, early adverse tissue responses, and genotoxicity. Finally, some of the current in vivo models used for the analysis of tissue response to various wear particles are presented.

  5. "Work smart, wear your hard hat"

    CERN Multimedia


    Falling objects and collisions are frequent occurrences in work sites and hazardous areas. Hard hats can help prevent many types of accident and can even save lives. Just imagine an 800 g spanner falling from a 13 m high scaffold onto the head of someone standing below - a nightmare scenario! The impact to the head is equivalent to that of a 5 kg weight falling from 2 metres. That is just what happened to Gerd Fetchenhauer when he was working on the UA1 experiment. Fortunately, he was wearing a hard hat at the time. "That hat saved my life," he explains. "It punched a hole right through the hat and I was a bit dazed for a couple of hours but otherwise I was OK." Since that day, Gerd Fetchenhauer, now working on CMS, is never seen on a work site without his hard hat on. Work sites have proliferated at CERN with the construction of the LHC and its detectors, and the wearing of hard hats is compulsory (not to mention life-saving). In the underground caverns and experiment halls, where gantry cranes and other h...

  6. Influence of Thermal Cycling on Flexural Properties and Simulated Wear of Computer-aided Design/Computer-aided Manufacturing Resin Composites. (United States)

    Tsujimoto, A; Barkmeier, W W; Takamizawa, T; Latta, M A; Miyazaki, M

    The purpose of this study was to evaluate the influence of thermal cycling on the flexural properties and simulated wear of computer-aided design/computer-aided manufacturing (CAD/CAM) resin composites. The six CAD/CAM resin composites used in this study were 1) Lava Ultimate CAD/CAM Restorative (LU); 2) Paradigm MZ100 (PM); 3) CERASMART (CS); 4) Shofu Block HC (SB); 5) KATANA AVENCIA Block (KA); and 6) VITA ENAMIC (VE). Specimens were divided randomly into two groups, one of which was stored in distilled water for 24 hours, and the other of which was subjected to 10,000 thermal cycles. For each material, 15 specimens from each group were used to determine the flexural strength and modulus according to ISO 6872, and 20 specimens from each group were used to examine wear using a localized wear simulation model. The test materials were subjected to a wear challenge of 400,000 cycles in a Leinfelder-Suzuki device (Alabama machine). The materials were placed in custom-cylinder stainless steel fixtures, and simulated localized wear was generated using a stainless steel ball bearing (r=2.387 mm) antagonist in a water slurry of polymethyl methacrylate beads. Simulated wear was determined using a noncontact profilometer (Proscan 2100) with Proscan and AnSur 3D software. The two-way analysis of variance of flexural properties and simulated wear of CAD/CAM resin composites revealed that material type and thermal cycling had a significant influence (p0.05) between the two factors. The flexural properties and maximum depth of wear facets of CAD/CAM resin composite were different (pinfluenced (p>0.05) by thermal cycling, except in the case of VE. The volume losses in wear facets on LU, PM, and SB after 10,000 thermal cycles were significantly higher (pinfluenced by thermal cycling.

  7. Expanding subjectivities

    DEFF Research Database (Denmark)

    Lundgaard Andersen, Linda; Soldz, Stephen


    A major theme in recent psychoanalytic thinking concerns the use of therapist subjectivity, especially “countertransference,” in understanding patients. This thinking converges with and expands developments in qualitative research regarding the use of researcher subjectivity as a tool to understa...

  8. How quantity and quality of brace wear affect the brace treatment outcomes for AIS. (United States)

    Lou, Edmond H M; Hill, Douglas L; Raso, Jim V; Moreau, Marc; Hedden, Douglas


    To determine the reliability of a prognostic curve progression model and the role of the quantity and quality of brace wear for adolescent idiopathic scoliosis (AIS) brace treatment. To develop a curve progression model for full-time AIS brace treatment, 20 AIS subjects (Group 1) prescribed full-time thoracolumbar sacral orthosis (TLSO) were monitored and followed for 2 years beyond maturity. The developed curve progression model was: curve progression (in degrees) = 33 + 0.11 × Peterson risk (%) - 0.07 in-brace correction (%) - 0.45 × quality (%) - 0.48 × quantity (%) + 0.0062 × quantity × quality. To validate the model, 40 new (test) subjects (Group 2) who met the same inclusion criteria and used the same type of monitors, were monitored and followed for 2 years after bracing. For the 40 test subjects (Group 2), the average in-brace correction was 40 ± 22 %. The average quantity and quality of the brace wear were 56 ± 19 and 55 ± 17 %, respectively. Twelve subjects (30 %) progressed of which 10 subjects (25 %) required surgery and 28 subjects (70 %) showed no progression. The accuracy of the model to determine which patients would progress was 88 % (35/40) which was better than the Peterson's risk model (68 %; 26/40) alone. Patients who had the combined quantity times the quality over a threshold 43 % had a success treatment rate of 95 %. This study showed the prognostic model of brace treatment outcome on AIS patients treated with full-time TLSO was reliable. Both the quantity and quality of the brace wear were important factors in achieving successful brace treatment.

  9. Resistance to Abrasive Wear and Volume Fraction of Carbides in Cast High-manganese Austenitic Steel with Composite Structure

    Directory of Open Access Journals (Sweden)

    Tęcza G.


    Full Text Available Cast Hadfield steel is characterised by high abrasion resistance, provided, however, that it is exposed to the effect of dynamic loads. During abrasion without loading, e.g. under the impact of loose sand jet, its wear resistance drops very drastically. To increase the abrasion resistance of this alloy under the conditions where no pressure is acting, primary vanadium carbides are formed in the metallurgical process, to obtain a composite structure after the melt solidification. The primary, very hard, carbides uniformly distributed in the austenitic matrix are reported to double the wear resistance of samples subjected to the effect of a silicon carbide-water mixture.

  10. Quality control methods in accelerometer data processing: defining minimum wear time.

    Directory of Open Access Journals (Sweden)

    Carly Rich

    Full Text Available BACKGROUND: When using accelerometers to measure physical activity, researchers need to determine whether subjects have worn their device for a sufficient period to be included in analyses. We propose a minimum wear criterion using population-based accelerometer data, and explore the influence of gender and the purposeful inclusion of children with weekend data on reliability. METHODS: Accelerometer data obtained during the age seven sweep of the UK Millennium Cohort Study were analysed. Children were asked to wear an ActiGraph GT1M accelerometer for seven days. Reliability coefficients(r of mean daily counts/minute were calculated using the Spearman-Brown formula based on the intraclass correlation coefficient. An r of 1.0 indicates that all the variation is between- rather than within-children and that measurement is 100% reliable. An r of 0.8 is often regarded as acceptable reliability. Analyses were repeated on data from children who met different minimum daily wear times (one to 10 hours and wear days (one to seven days. Analyses were conducted for all children, separately for boys and girls, and separately for children with and without weekend data. RESULTS: At least one hour of wear time data was obtained from 7,704 singletons. Reliability increased as the minimum number of days and the daily wear time increased. A high reliability (r = 0.86 and sample size (n = 6,528 was achieved when children with ≥ two days lasting ≥10 hours/day were included in analyses. Reliability coefficients were similar for both genders. Purposeful sampling of children with weekend data resulted in comparable reliabilities to those calculated independent of weekend wear. CONCLUSION: Quality control procedures should be undertaken before analysing accelerometer data in large-scale studies. Using data from children with ≥ two days lasting ≥10 hours/day should provide reliable estimates of physical activity. It's unnecessary to include only children

  11. Development of wear-resistant ceramic coatings for diesel engine components

    Energy Technology Data Exchange (ETDEWEB)

    Naylor, M.G.S. (Cummins Engine Co., Inc., Columbus, IN (United States))


    The tribological properties of a variety of advanced coating materials have been evaluated under conditions which simulate the piston ring -- cylinder liner environment near top ring reversal in a heavy duty diesel engine. Coated ring'' samples were tested against a conventional pearlitic grey cast iron liner material using a high temperature reciprocating wear test rig. Tests were run with a fresh CE/SF 15W40lubricant at 200 and 350{degrees}C, with a high-soot, engine-tested oil at 200{degrees}C and with no lubrication at 200{degrees}C. For lowest wear under boundary lubricated conditions, the most promising candidates to emerge from this study were high velocity oxy-fuel (HVOF) Cr{sub 3} C{sub 2} - 20% NiCr and WC - 12% Co cermets, low temperature arc vapor deposited (LTAVD) CrN and plasma sprayed chromium oxides. Also,plasma sprayed Cr{sub 2}O{sub 3} and A1{sub 2}O{sub 3}-ZrO{sub 2} materials were found to give excellent wear resistance in unlubricated tests and at extremely high temperatures (450{degrees}C) with a syntheticoil. All of these materials would offer substantial wear reductions compared to the conventional electroplated hard chromium ring facing and thermally sprayed metallic coatings, especially at high temperatures and with high-soot oils subjected to degradation in diesel environments. The LTAVD CrN coating provided the lowest lubricated wear rates of all the materials evaluated, but may be too thin (4 {mu}m) for use as a top ring facing. Most of the coatings evaluated showed higher wear rates with high-soot, engine-tested oil than with fresh oil, with increases of more than a factor of ten in some cases. Generally, metallic materials were found to be much more sensitive to soot/oil degradation than ceramic and cermet coatings. Thus, decreased soot sensitivity'' is a significant driving force for utilizing ceramic or cermet coatings in diesel engine wear applications.

  12. Analysis of Wear Particles Formed in Boundary-Lubricated Sliding Contacts

    NARCIS (Netherlands)

    Akchurin, Aydar; Bosman, Rob; Lugt, Pieter Martin; van Drogen, Mark


    The wear process in a sliding contact results in generation of wear debris, which affects the system life. The impact depends on the wear particle properties, such as size, shape and number. In this paper, the wear particles formed during a cylinder-on-disk wear test were examined. PAO additive-free

  13. Effects of Wearing Different Personal Equipment on Force Distribution at the Plantar Surface of the Foot

    Directory of Open Access Journals (Sweden)

    Christoph Schulze


    Full Text Available Background. The wearing of personal equipment can cause specific changes in muscle activity and posture. In the present study, we investigated the influence of differences in equipment related weight loading and load distribution on plantar pressure. In addition, we studied functional effects of wearing different equipment with a particular focus on relevant changes in foot shape. Methods. Static and dynamic pedobarography were performed on 31 male soldiers carrying increasing weights consisting of different items of equipment. Results. The pressure acting on the plantar surface of the foot increased with higher loading, both under static and dynamic conditions (p < 0.05. We observed an increase in the contact area (p < 0.05 and an influence of load distribution through different ways to carry the rifle. Conclusions. The wearing of heavier weights leads to an increase in plantar pressure and contact area. This may be caused by flattening of the transverse and longitudinal arches. The effects are more evident in subjects with flat feet deformities which seem to flatten at an earlier load condition with a greater amount compared to subjects with normal arches. Improving load distribution should be a main goal in the development of military equipment in order to prevent injuries or functional disorders of the lower extremity.

  14. Tempering-Induced Microstructural Changes in the Weld Heat-Affected Zone of 9 to 12 Pct Cr Steels and Their Influence on Sliding Wear (United States)

    Velkavrh, Igor; Kafexhiu, Fevzi; Klien, Stefan; Diem, Alexander; Podgornik, Bojan


    Increasing amount of tribological applications is working under alternating high/low temperature conditions where the material is subjected to temperature fatigue mechanisms such as creep, softening due to annealing, and at the same time must withstand mechanical wear due to sliding contact with pairing bodies. Steam turbine valves, gate valves, valve heads, stems, seats and bushings, and contacting surfaces of the carrier elements are some examples of such applications. The purpose of the present study is to evaluate the potential of X20 and P91 steels as materials for applications operating under combined effect of mechanical wear and alternating high/low temperature conditions. It was focused on how the microstructural changes occurring in the weld zone affect the wear properties of the selected materials. Generally, with longer tempering time and higher tempering temperature, the number of carbide precipitates decreased, while their relative spacing increased. Before tempering, the morphology of the steel matrix (grain size, microstructure homogeneity) governed the wear resistance of both steels, while after tempering wear response was determined by the combination of the number and the size of carbide particles. After tempering, in X20 steel larger number of stable M23C6 carbides was observed as compared with P91 steel, resulting in lower wear rates. It was observed that for both steels, a similar combination of number density and size distribution of carbide particles provided the highest wear resistance.

  15. Investigation on two-body abrasive wear behavior of titanium ...

    African Journals Online (AJOL)

    Investigation on two-body abrasive wear behavior of titanium carbide filled glass fabric-epoxy composites- a Box-Behnken approach. ... International Journal of Engineering, Science and Technology ... The two-body abrasive wear behavior of Glass–Epoxy (G–E) composites has been evaluated by the addition of Titanium

  16. Anisotropy abrasive wear behavior of bagasse fiber reinforced ...

    African Journals Online (AJOL)

    Anisotropy abrasive wear behavior of bagasse fiber reinforced polymer composite. ... International Journal of Engineering, Science and Technology ... Three different types of abrasives wear behaviour have been observed in the composite in three orientations and follow the following trends: WNO < WAPO < WPO, where ...

  17. Assessment of mechanical and three-body abrasive wear peculiarity ...

    Indian Academy of Sciences (India)

    by using VIKOR method. Keywords. Mechanical property; three-body abrasive wear; Taguchi methodology; surface morphology; VIKOR ... wear behaviour of filled epoxy composite systems and concluded that low wt% of boron ... process, which was supported by SEM (scanning electron microscope) studies (reduced ...

  18. Tooth -Wear Lesions Among Patients Attending Tertiary Hospital in ...

    African Journals Online (AJOL)

    Tooth wear manifest in the form of abrasion, attrition, erosion and abfraction and can affect the quality of life of the sufferer. This was a prospective study of patients who ... We recommend oral hygiene advice, dietary counseling and regular dental examination for early detection. Key words: Tooth wear, lesion, prospective, ...

  19. Fracture mechanics approach to estimate rail wear limits (United States)


    This paper describes a systematic methodology to estimate allowable limits for rail head wear in terms of vertical head-height loss, gage-face side wear, and/or the combination of the two. This methodology is based on the principles of engineering fr...

  20. Clinical studies of dental erosion and erosive wear

    NARCIS (Netherlands)

    Huysmans, M.C.D.N.J.M.; Chew, H.P.; Ellwood, R.P.


    We define erosion as a partial demineralisation of enamel or dentine by intrinsic or extrinsic acids and erosive tooth wear as the accelerated loss of dental hard tissue through the combined effect of erosion and mechanical wear (abrasion and attrition) on the tooth surface. Most experts believe

  1. 16 CFR 423.6 - Textile wearing apparel. (United States)


    ... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Textile wearing apparel. 423.6 Section 423.6 Commercial Practices FEDERAL TRADE COMMISSION TRADE REGULATION RULES CARE LABELING OF TEXTILE WEARING APPAREL... the outside of the package or on a hang tag fastened to the product. (b) Care labels must state what...

  2. Using Noncontingent Reinforcement to Increase Compliance with Wearing Prescription Prostheses (United States)

    Richling, Sarah M.; Rapp, John T.; Carroll, Regina A.; Smith, Jeanette N.; Nystedt, Aaron; Siewert, Brook


    We evaluated the effects of noncontingent reinforcement (NCR) on compliance with wearing foot orthotics and a hearing aid with 2 individuals. Results showed that NCR increased the participants' compliance with wearing prescription prostheses to 100% after just a few 5-min sessions, and the behavior change was maintained during lengthier sessions.…

  3. Barriers to Wearing Glasses Among Primary School Children in ...

    African Journals Online (AJOL)

    For those that genuinely had deep-rooted beliefs against wearing glasses, health education by teaching the benefits of wearing glasses could be of great help. We appeal to private eye care service deliverers to accommodate school children and to offer services to them at affordable costs including provision of glasses.

  4. A study on wear behaviour of Al/6101/graphite composites

    Directory of Open Access Journals (Sweden)

    Pardeep Sharma


    Full Text Available The current research work scrutinizes aluminium alloy 6101-graphite composites for their mechanical and tribological behaviour in dry sliding environments. The orthodox liquid casting technique had been used for the manufacturing of composite materials and imperilled to T6 heat treatment. The content of reinforcement particles was taken as 0, 4, 8, 12 and 16 wt.% of graphite to ascertain it is prospective as self-lubricating reinforcement in sliding wear environments. Hardness, tensile strength and flexural strength of cast Al6101 metal matrix and manufactured composites were evaluated. Hardness, tensile strength and flexural strength decreases with increasing volume fraction of graphite reinforcement as compared to cast Al6101 metal matrix. Wear tests were performed on pin on disc apparatus to assess the tribological behaviour of composites and to determine the optimum volume fraction of graphite for its minimum wear rate. Wear rate reduces with increase in graphite volume fraction and minimum wear rate was attained at 4 wt.% graphite. The wear was found to decrease with increase in sliding distance. The average co-efficient of friction also reduces with graphite addition and its minimum value was found to be at 4 wt.% graphite. The worn surfaces of wear specimens were studied through scanning electron microscopy. The occurrence of 4 wt.% of graphite reinforcement in the composites can reveal loftier wear possessions as compared to cast Al6101 metal matrix.

  5. Occlusal wear of provisional implant-supported restorations

    NARCIS (Netherlands)

    Santing, Hendrik J.; Kleverlaan, Cornelis J.; Werner, Arie; Feilzer, Albert J.; Raghoebar, Gerry M.; Meijer, Henny J. A.

    BACKGROUND: Implant-supported provisional restorations should be resistant to occlusal wear. PURPOSE: The purpose of this laboratory study was to evaluate three-body wear of three indirect laboratory composite resins, five chair side bis-acryl resin-based materials, and two chair side

  6. Multi technical analysis of wear mechanisms in axial piston pumps (United States)

    Schuhler, G.; Jourani, A.; Bouvier, S.; Perrochat, J.-M.


    Axial piston pumps convert a motor rotation motion into hydraulic or pneumatic power. Their compactness and efficiency of approximately 0.9 make them suitable for actuation applications especially in aeronautics. However, they suffer a limited life due to the wear of their components. In the literature, studies of axial piston pumps deal with contact between its different elements under lubrication conditions. Nevertheless, they are more focused on analytic or numerical approaches. This study consists in an experimental analysis of worn pump components to highlight and understand wear mechanisms. Piston shoes are central components in the axial piston pump since they are involved in three tribological contacts. These three contacts are thereby studied: piston shoes/swashplate, piston shoes/pistons and piston shoes/shoes hold down plate (SHDP). To perform this analysis, helicopter hydraulic pumps after different operating times have been studied. The wear damage mechanisms and wear debris are analysed using SEM observations. 3D surface roughness measurements are then used to characterize worn surfaces. The observations reveal that in the contact between shoes and swashplate, the main wear mechanism is three-body abrasive wear due to coarse carbides removal. Between shoes and pistons, wear occurs in a less severe way and is mainly due to the debris generated in the first contact and conveyed by the lubricating fluid. In the third contact, the debris are also the prime cause of the abrasive wear and the generation of deep craters in the piston shoes.

  7. The Tooth Wear Evaluation System: development and applications

    NARCIS (Netherlands)

    Wetselaar, P.


    Tooth wear is a multifactorial condition, leading to the loss of dental hard tissues, viz., enamel and dentine. Because of its multifactorial etiology, tooth wear can manifest itself in many different representations, and therefore it can be difficult and demanding to diagnose and manage the

  8. Severe Tooth Wear: European Consensus Statement on Management Guidelines.

    NARCIS (Netherlands)

    Loomans, B.; Opdam, N.J.; Attin, T.; Bartlett, D.; Edelhoff, D.; Frankenberger, R.; Benic, G.; Ramseyer, S.; Wetselaar, P.; Sterenborg, B.; Hickel, R.; Pallesen, U.; Mehta, S.; Banerji, S.; Lussi, A.; Wilson, N.


    This paper presents European expert consensus guidelines on the management of severe tooth wear. It focuses on the definition of physiological vs pathological tooth wear and recommends diagnosis, prevention, counseling, and monitoring aimed at elucidating the etiology, nature, rate and means of

  9. Monitoring of dry sliding wear using fractal analysis

    NARCIS (Netherlands)

    Zhang, Jindang; Regtien, Paulus P.L.; Korsten, Maarten J.


    Reliable online monitoring of wear remains a challenge to tribology research as well as to the industry. This paper presents a new method for monitoring of dry sliding wear using digital imaging and fractal analysis. Fractal values, namely fractal dimension and intercept, computed from the power

  10. Size dependence of nanoscale wear of silicon carbide (United States)

    Chaiyapat Tangpatjaroen; David Grierson; Steve Shannon; Joseph E. Jakes; Izabela Szlufarska


    Nanoscale, single-asperity wear of single-crystal silicon carbide (sc- SiC) and nanocrystalline silicon carbide (nc-SiC) is investigated using single-crystal diamond nanoindenter tips and nanocrystalline diamond atomic force microscopy (AFM) tips under dry conditions, and the wear behavior is compared to that of single-crystal silicon with both thin and thick native...

  11. Wear Resistance of Steel 20MnCr5 After Surfacing with Micro-jet Cooling

    Directory of Open Access Journals (Sweden)

    Tarasiuk W.


    Full Text Available This paper presents results of experimental research concerning the impact of an innovative method of micro-jet cooling on the padding weld performed with MIG welding. Micro-jet cooling is a novel method patented in 2011. It enables to steer the parameters of weld cooling in a precise manner. In addition, various elements which may e.g. enhance hardness or alter tribological properties can be entered into its top surface, depending on the applied cooling gas. The material under study was steel 20MnCr5, which was subject to the welding process with micro-jet cooling and without cooling. Nitrogen was used as a cooling gas. The main parameter of weld assessment was wear intensity. The tests were conducted in a tribological pin-on-disc type position. The following results exhibit growth at approximately 5% in wear resistance of padding welds with micro-jet cooling.

  12. The association between wear facets, bruxism, and severity of facial pain in patients with temporomandibular disorders. (United States)

    Pergamalian, Anna; Rudy, Thomas E; Zaki, Hussein S; Greco, Carol M


    It is unclear whether patients with temporomandibular disorders (TMD) who report high levels of bruxism have more severe signs and symptoms of TMD and more advanced tooth wear than patients with TMD who report lower levels of bruxism. The purpose of this study was to determine whether there was a significant association between tooth wear, the parafunctional oral habit of bruxism, temporomandibular joint (TMJ) pain, and muscle pain severity in a TMD population. A total of 84 subjects previously diagnosed with TMD, according to the Research Diagnostic Criteria for TMD (RDC/TMD) and who met 10 specific inclusion/exclusion criteria underwent a thorough multiaxial examination and classification recommended by the National Institute of Dental and Craniofacial Research (NIDCR). Measurement of tooth wear facets by use of a 4-point scale were graded in 10 zones on mandibular casts. One calibrated examiner performed all scoring. Bruxism was assessed in a standardized pretreatment questionnaire and in the dental history and interview (RDC/TMD) to indicate how frequently (0 = never to 3 = very often) subjects performed a list of oral habits, which included bruxism. The Kappa reliability coefficient (range from: -1.0 to 1.0) was used to correct for chance agreement, and was computed for each of the 10 study sites designated for rating. Subjects were also compared for muscle and joint pain. Muscle pain was a summed measure derived from the dental examination findings (range 0 to 20), calculated from the presence or absence of pain induced by palpation of 20 predetermined muscle sites. Similarly, joint pain was a summed measure of the presence or absence of pain in the TMJs induced by palpation of the joints on the outer surface and in the external auditory canal in 5 different positions of the mandible. A Pearson product-moment correlation was used to compute the summed severity of tooth wear and the subjects' age. Analysis of covariance was used to determine whether the number

  13. Nitrocarburizing for wear, corrosion, and fatigue

    Energy Technology Data Exchange (ETDEWEB)

    Wahl, G. [Durferrit GmbH Thermotechnik, Hanau (Germany)


    Demands for higher strength and corrosion resistance at higher temperatures cannot always be met by advanced materials and designs alone. In many cases, surface engineering can provide required properties and extend service life. A thermochemical surface engineering treatment has been developed that improves the dynamic strength of parts and overcomes many corrosion and wear problems. Known as Melonite, the process was developed by Durferrite GmbH Thermotechnik, and is used to enhance the surface properties of steel and iron parts. The quench, quench-polish, and quench-polish-quench salt bath nitrocarburizing system can provide surface layers with a range of beneficial properties. This article will discuss details of the Melonite process, component properties after treatment, the effects of raising or lowering treatment temperatures, and environmental impact.

  14. Wear Resistance Limited by Step Edge Failure: The Rise and Fall of Graphene as an Atomically Thin Lubricating Material. (United States)

    Qi, Yizhou; Liu, Jun; Zhang, Ji; Dong, Yalin; Li, Qunyang


    Owing to its intrinsically lubricious property, graphene has a high potential to be an atomically thin solid lubricant for sliding interfaces. Despite its ultrahigh breaking strength at the nanoscale, graphene often fails to maintain its integrity when subjected to macroscale tribological tests. To reveal the true wear characteristics of graphene, a nanoscale diamond tip was used to scratch monolayer graphene mechanically exfoliated to SiO2 substrates. Our experimental results show that while graphene exhibited extraordinary wear resistance in the interior region, it could be easily damaged at the step edge under a much lower normal load (∼2 orders of magnitude smaller). Similar behavior with substantially reduced wear resistance at the edge was also observed for monatomic graphene layer on graphite surface. Using molecular dynamics simulations, we attributed this markedly weak wear resistance at the step edge to two primary mechanisms, i.e., atom-by-atom adhesive wear and peel induced rupture. Our findings shed light on the paradox that graphene is nanoscopically strong yet macroscopically weak. As step edge is ubiquitous for two-dimensional materials at the macroscale, our study also provides a guiding direction for maximizing the mechanical and tribological performance of these atomically thin materials.

  15. Wear Properties of Nuclear Graphite IG-110 at Elevated Temperature

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Dunkun; Kim, Jaehoon; Kim, Yeonwook [Chungnam National University, Daejeon (Korea, Republic of)


    The high temperature gas-cooled reactor (HTR-10) is designed to produce electricity and hydrogen. Graphite is used as reflector, support structures, and a moderator in reactor core; it has good resistance to neutron and is a suitable material at high temperatures. Friction is generated in the graphite structures for the core reflector, support structures, and moderator because of vibration from the HTR-10 fuel cycle flow. In this study, the wear characteristics of the isotropic graphite IG-110 used in HTR-10 were evaluated. The reciprocating wear test was carried out for graphite against graphite. The effects of changes in the contact load and sliding speeds at room temperature and 400℃ on the coefficient of friction and specific wear rate were evaluated. The wear behavior of graphite IG-110 was evaluated based on the wear surfaces.

  16. Enhanced DLC wear performance by the presence of lubricant additives

    Directory of Open Access Journals (Sweden)

    Romina Paula de Castro Costa


    Full Text Available Lubricant additives play significant role for reducing friction and wear of mechanical elements. The additives presented in 5W30 oil were developed for metal surfaces. However, they have been used in engine pieces covered with DLC coatings because they also offer the potential to reduce friction losses and wear in automotive applications. The friction and wear tests were carried out by using a UMT-CETR ball-on-disk tribometer in rotational mode under 5W30 synthetic oil at 100 °C. The X-ray photoelectron spectroscopy (XPS showed the presence of Mo and S in the wear tracks. These elements are from decomposition of ZDDP and MoDTC additives producing MoS2 in DLC surface, which offers enhanced durability by low wear rate.

  17. Quasi-nano wear mechanism under repeated impact contact loading

    Institute of Scientific and Technical Information of China (English)


    A new quasi-nano wear mechanism (QNWM) has been proposed in this paper based on the facts of wear curve turning under high energy impact contact loading.Its characteristic is that the wear rate of QNWM is only 1/10-1/3 that of delamination mechanism at the same energy density.The diameters of wear debris and pits on the worn surfaces fall into the quasi-nanometer scale (about 50-120 nm).The necessary and sufficient conditions,which bring about the QNWM,are:(i) the nano-structure (nano-crystalline + amorphous phase) in impact contact surface layer has formed by the intensive impact strain;(ii) the delamination wear cracking in sub-surface layer must be restrained;(iii) the microcracks of QNWM are produced in amorphous phase of surface nano-structure layer rather than in nano-crystalline.

  18. Gradients of occlusal wear in hunter-gatherers and agriculturalists. (United States)

    Deter, Christina A


    Occlusal wear was recorded in maxillary teeth from three North American late Archaic (3385 +/- 365 cal BC) hunter-gatherer sites (n = 306) and late Anasazi-early Zuni agricultural sites ( approximately 1300 AD) (n = 87). Comparisons were undertaken using descriptive and inferential statistics to determine differences between these groups, and along the maxillary tooth row. The hunter-gatherers had a significantly greater percentage of occlusal wear than the agriculturalists. For both hunter-gatherers and agriculturalists, occlusal wear was greatest on the central incisors and first molars. The third molars had the least amount of wear. It was inferred from these results that the hunter-gatherers had a more abrasive diet, and different daily task activities compared to the agriculturalists. One further finding was that wear patterns on anterior and posterior teeth are influenced by the order that teeth erupt into the jaw, as well as diet and behavior. (c) 2008 Wiley-Liss, Inc.

  19. Optical coherence tomography applied to the evaluation of wear of composite resin for posterior teeth (United States)

    Mota, Cláudia C. B. O.; Guerra, Bruna A.; Machado, Brena S. A.; Cabral, Adolfo J.; Gomes, Anderson S. L.


    Resin composites are widely used as restorative materials due to their excellent aesthetical and mechanical properties. Posterior teeth are constantly submitted to occlusal stress and upon restoration require more resistant resins. The aim of this study was to analyze in vitro the wear suffered over time by restorations in resin composite in posterior teeth, by Optical Coherence Tomography (OCT). 30 molars had occlusal cavities prepared and were randomly divided into three groups (n=10) and restored with resin composite: G1: Filtek P90 (3M/ESPE), G2: Tetric N-Ceram (Ivoclar Vivadent); G3: Filtek P60 (3M/ESPE). Specimens were subjected to initial analysis by OCT (OCP930SR, Thorlabs, axial resolution 6.2 μm) and stereoscopic microscope. Specimens were submitted to thermocycling (500 cycles, 5-55 °C) and subjected to simulated wear through a machine chewing movements (Wear Machine WM001), projecting four years of use. After mechanical cycles, the specimens were submitted to a second evaluation by the OCT and stereoscopic microscopy. As a result, it was observed that 90% of the restorations of both groups had fractures and/or points of stress concentration, considered niches for early dissemination of new fracture lines. It was also found that G1 and G2 had more points of stress concentration, whereas G3 had a higher incidence of fracture lines already propagated. It was concluded that the G3 showed more brittle behavior at the masticatory wear when compared to G1 and G2.

  20. An energy dissipation and cross shear time dependent computational wear model for the analysis of polyethylene wear in total knee replacements. (United States)

    O'Brien, Sean T; Bohm, Eric R; Petrak, Martin J; Wyss, Urs P; Brandt, Jan-M


    The cost and time efficiency of computational polyethylene wear simulations may enable the optimization of total knee replacements for the reduction of polyethylene wear. The present study proposes an energy dissipation wear model for polyethylene which considers the time dependent molecular behavior of polyethylene, aspects of tractive rolling and contact pressure. This time dependent - energy dissipation wear model was evaluated, along with several other wear models, by comparison to pin-on-disk results, knee simulator wear test results under various kinematic conditions and knee simulator wear test results that were performed following the ISO 14243-3 standard. The proposed time dependent - energy dissipation wear model resulted in improved accuracy for the prediction of pin-on-disk and knee simulator wear test results compared with several previously published wear models. Crown Copyright © 2014. Published by Elsevier Ltd. All rights reserved.

  1. Peripheral corneal infiltrates associated with contact lens wear. (United States)

    Suchecki, J K; Ehlers, W H; Donshik, P C


    We describe the epidemiological and clinical characteristics of peripheral corneal infiltrates associated with contact lens wear. We conducted a retrospective study of 52 patients with contact lens associated peripheral corneal infiltrates. Demographic data, clinical characteristics of the infiltrates, contact lens parameters, treatment modality, and the time to resolution for the infiltrates were analyzed. Forty-four of the 52 patients in this study presented with a single infiltrate, while the remaining 8 patients had multiple infiltrates. Types of contact lenses worn were as follows: 40% of the patients wore disposable extended wear contact lenses; 21% wore conventional extended wear lenses; 19% wore conventional daily wear lenses; 12% used frequent replacement daily wear lenses; 6% wore rigid gas permeable (RGP) contact lenses; and 2% used disposable lenses as daily wear. Although there was no predilection for a specific quadrant of the cornea, when a subgroup of extended wear contact lens patients was analyzed, 19 of their 40 infiltrates were located in the superior quadrant. The epithelium was intact in 42% of the infiltrates, while 58% of the infiltrates had epithelial involvement, either punctate staining or frank defect. Eight of the 16 patients who had corneal cultures performed had positive cultures. All patients who had positive cultures used extended wear contact lenses. Smoking did not appear to have an effect on the associated inflammatory reaction, positive cultures, or time to resolution. Seventy-five percent of patients were treated with topical antibiotics. Antibiotic steroids were prescribed for 23% of patients, and 2% of patients were treated with topical steroids. The mean time to resolution for all infiltrates was 1.74 weeks. Focal peripheral infiltrates with or without epithelial disturbance represent a distinct clinical complication associated with contact lens wear. All patients in this study had resolution of their infiltrates without

  2. Prevalence and Indicators of Tooth Wear among Chinese Adults.

    Directory of Open Access Journals (Sweden)

    Zhao Wei

    Full Text Available Numerous epidemiological studies have focused on the prevalence and related indicators of tooth wear. However, no sufficient studies have been conducted with Chinese adults. The purpose of this study was to assess the prevalence of tooth wear and identify related indicators among adults aged 36 to 74 years in Wuhan City, P.R. China. A cross-sectional and analytic study was conducted with 720 participants, aged 35-49 yrs and 50-74 yrs, in 2014. Each age group included 360 participants, of which 50% were males and 50% were females. All participants completed a questionnaire before examination. Tooth wear was assessed using the modified Basic Erosive Wear Examination (BEWE index. The data were analyzed using the chi-square test and binary logistic regression analysis. The prevalence of tooth wear was 67.5% and 100% in the 35-49 and 50-74 age groups, respectively. The prevalence of dentin exposure was 64.7% and 98.3%, respectively. A significantly higher prevalence of tooth wear and dentin exposure was found in the 50-74 yr group than in the 35-49 yr group (p < 0.05. Critical indicators of tooth wear and dentin exposure included high frequency of acidic drinks and foods consumption, low socio-economic status, and unilateral chewing. The frequency of changing toothbrushes and the habit of drinking water during meals were associated with tooth wear. In addition, the usage of hard-bristle toothbrushes and consuming vitamin C and aspirin were found to be linked with dentin exposure. In conclusion, the prevalence of tooth wear and dentin exposure observed in Chinese adults was high, and the results revealed an association between tooth wear and socio-behavioral risk indicators.

  3. Friction and wear behaviour of self lubricating bearing liners (United States)

    Gay, Russell

    The thesis describes a numerical model for evaluating the variation of friction and wear of a self lubricating bearing liner over its useful wear life. Self-lubricating bearings have been in widespread use since the mid-1950s, particularly in the aerospace industry where they have the advantage of being low maintenance components. They are commonly used in relatively low speed, reciprocating applications such as control surface actuators, and usually consist of a spherical bearing with the inner and outer elements separated by a composite textile resin-bonded liner. A finite element model has been developed to predict the local stiffness of a particular liner at different states of wear. Results obtained using the model were used to predict the overall friction coefficient as it evolves due to wear, which is a novel approach. Experimental testing was performed on a bespoke flat-on-flat wear test rig with a reciprocating motion to validate the results of the friction model.. These tests were carried out on a commercially-available bearing liner, predominantly at a high contact pressure and an average sliding speed of 0.2 ms-1. Good agreement between predicted and experimentally measured wear was obtained when appropriate coefficients of friction were used in the friction model, and when the reciprocating sliding distance was above a critical value. A numerical wear model was also developed to predict the trend of backlash development in real bearing geometries using a novel approach. Results from the wear model were validated against full-scale bearing tests carried out elsewhere by the sponsoring company. Good agreement was obtained between the model predictions and the experimental results for the first 80% of the bearing wear life, and explanations for the discrepancy during the last 20% of the wear life have been proposed..

  4. Wear behavior of pressable lithium disilicate glass ceramic. (United States)

    Peng, Zhongxiao; Izzat Abdul Rahman, Muhammad; Zhang, Yu; Yin, Ling


    This article reports effects of surface preparation and contact loads on abrasive wear properties of highly aesthetic and high-strength pressable lithium disilicate glass-ceramics (LDGC). Abrasive wear testing was performed using a pin-on-disk device in which LDGC disks prepared with different surface finishes were against alumina pins at different contact loads. Coefficients of friction and wear volumes were measured as functions of initial surface finishes and contact loads. Wear-induced surface morphology changes in both LDGC disks and alumina pins were characterized using three-dimensional laser scanning microscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy. The results show that initial surface finishes of LDGC specimens and contact loads significantly affected the friction coefficients, wear volumes and wear-induced surface roughness changes of the material. Both wear volumes and friction coefficients of LDGC increased as the load increased while surface roughness effects were complicated. For rough LDGC surfaces, three-body wear was dominant while for fine LDGC surfaces, two-body abrasive wear played a key role. Delamination, plastic deformation, and brittle fracture were observed on worn LDGC surfaces. The adhesion of LDGC matrix materials to alumina pins was also discovered. This research has advanced our understanding of the abrasive wear behavior of LDGC and will provide guidelines for better utilization and preparation of the material for long-term success in dental restorations. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 968-978, 2016. © 2015 Wiley Periodicals, Inc.

  5. Wear-caused deflection evolution of a slide rail, considering linear and non-linear wear models (United States)

    Kim, Dongwook; Quagliato, Luca; Park, Donghwi; Murugesan, Mohanraj; Kim, Naksoo; Hong, Seokmoo


    The research presented in this paper details an experimental-numerical approach for the quantitative correlation between wear and end-point deflection in a slide rail. Focusing the attention on slide rail utilized in white-goods applications, the aim is to evaluate the number of cycles the slide rail can operate, under different load conditions, before it should be replaced due to unacceptable end-point deflection. In this paper, two formulations are utilized to describe the wear: Archard model for the linear wear and Lemaitre damage model for the nonlinear wear. The linear wear gradually reduces the surface of the slide rail whereas the nonlinear one accounts for the surface element deletion (i.e. due to pitting). To determine the constants to use in the wear models, simple tension test and sliding wear test, by utilizing a designed and developed experiment machine, have been carried out. A full slide rail model simulation has been implemented in ABAQUS including both linear and non-linear wear models and the results have been compared with those of the real rails under different load condition, provided by the rail manufacturer. The comparison between numerically estimated and real rail results proved the reliability of the developed numerical model, limiting the error in a ±10% range. The proposed approach allows predicting the displacement vs cycle curves, parametrized for different loads and, based on a chosen failure criterion, to predict the lifetime of the rail.

  6. Rod cluster control assemblies and rod cluster control guide tubes: wear and drop time; Grappes de commande et guides de grappes: usure et tempes de chute

    Energy Technology Data Exchange (ETDEWEB)

    Zbinden, M. [Electricite de France (EDF), Direction des Etudes et Recherches, 92 - Clamart (France)


    The wear of RCCAs and of RCC guide tubes is due to two quite different mechanisms and the remedies to apply for each case might lead to contradictory solutions: - the impact/sliding wear for the seldom moving RCCAs, namely the shutdown RCCAs, under flow-induced vibrations, - the axial sliding wear for the control rods subjected to the stepping movements ordered by the acting load. In this case the hydraulic sticking forces are those which produce an evolution of the surface states that may increase the drop time. The introduction, an historical survey of the encountered difficulties, is followed by short description of the components and then the paper presents contributions of EDF in the R and D field, which take place in two successive multi-annual projects. Lastly, some information is given about the recent evolutions and new problems as well for impact/sliding wear as for drop time under normal or seismic conditions. (author).

  7. Effect of wearing a palatal plate on swallowing function. (United States)

    Toyoshita, Yoshifumi; Koshino, Hisashi; Hirai, Toshihiro; Matsumi, Tamachi


    The purpose of this study was to determine the effect of wearing a palatal plate on swallowing function. The subject group consisted of 10 healthy, fully dentate males. Two experimental palatal plates (EPP) were used in this study: one was 1.4mm thick (EPP1), and the other was 2.8mm thick (EPP2). Tongue movements and swallowing sounds were simultaneously recorded. The position of the surface of the tongue was recorded by using ultrasound diagnostic equipment in the sagittal plane. Swallowing tests were performed under three conditions: without EPP (WOE), with EPP1 (WP1), and with EPP2 (WP2). Swallowing index (SI) and tongue contact time (TCT) was calculated. The value of SI was lowest under WOE, and highest under WP2, with a statistically significant difference. There was no statistical significance, however, between SI under WOE and that under WP1. The value of TCT was longest under WOE, and shortest under WP2, with a statistically significant difference. This investigation suggests that the thickness of a palatal plate influences SI and TCT, which correlate with swallowing function.

  8. Erosive Wear Characterization of Materials for Lunar Construction (United States)

    Mpagazehe, Jeremiah N.; Street, Kenneth W., Jr.; Delgado, Irebert R.; Higgs, C. Fred, III


    NASA s Apollo missions revealed that exhaust from the retrorockets of landing spacecraft may act to significantly accelerate lunar dust on the surface of the Moon. A recent study by Immer et al. (C. Immer, P.T. Metzger, P.E. Hintze, A. Nick, and R. Horan, Apollo 12 Lunar Module exhaust plume impingement on Lunar Surveyor III, Icarus, Vol. 211, pp. 1089-1102, 2011) investigated coupons returned to Earth from the Surveyor III lunar probe which were subjected to lunar dust impingement by the Apollo 12 Lunar Module landing. Their study revealed that even with indirect impingement, the spacecraft sustained erosive damage from the fast-moving lunar dust particles. In this work, results are presented from a series of erosive wear experiments performed on 6061 Aluminum using the JSC-1AF lunar dust simulant. Optical profilometry was used to investigate the surface after the erosion process. It was found that even short durations of lunar dust simulant impacting at low velocities produced substantial changes in the surface.

  9. Factors Affecting the Wear Resistance of Forging Tools

    Directory of Open Access Journals (Sweden)

    Zwierzchowski M.


    Full Text Available The durability of forging tools is a function of many variables: tool heat treatment, surface quality, temperature, pressure, number of forgings, diffusion layers (nitriding and many others. The objective of study was to analyze and compare the working conditions of forging tools. For the analysis of selected flat surfaces of tools. Analyzed forging dies subjected to normal use. Presented results of laboratory tests . The effect of temperature and time on the properties of the surface layer of forging tools. The results were compared with the literature data. This article shows the results of microhardness tests for forging dies which have forged the corresponding number of forgings. The results of laboratory studies on microhardness of hot working steel 1.2344 in the furnace at various temperatures and time are also presented. The working conditions of the forging tools are very complex. The most often described in the literature are: thermal fatigue, abrasive wear, mechanical fatigue and cracks. The article discusses the effects of increased temperature on the surface properties of forging tools. Forging dies were made of hot work tool steel 1.2344. FEM modeling of changes in the surface layer should take into account changes in tool hardness as a function of time (number of forgings.

  10. The Berkeley Contact Lens Extended Wear Study. Part II : Clinical results. (United States)

    Polse, K A; Graham, A D; Fusaro, R E; Gan, C M; Rivera, R K; Lin, M C; Sanders, T L; McNamara, N A; Chan, J S


    To describe the principal clinical outcomes associated with 12 months use of rigid gas-permeable (RGP) extended wear contact lenses and address two primary study questions: (1) does extended wear (EW) of high oxygen transmissibility (Dk/t) RGP lenses reduce the incidence of ocular complications, and (2) does the wearing of high-Dk/t lenses reduce the rate of failure to maintain 6-night RGPEW over 12 months? A randomized, concurrently controlled clinical trial. Subjects who adapted to EW with high Dk (oxygen permeability) RGP lenses were randomized to either high Dk or medium-Dk RGP lenses for 12 months of 6-night EW. Contact lens-associated keratopathies (CLAK), changes in refractive error and corneal curvature, and survival in EW. Two hundred one subjects were randomized to medium or high-Dk lenses for 12 months of EW. Sixty-two percent of the subjects in each group completed 12 months of EW; however, the probability of failure was significantly greater for the medium-Dk group. Although the risk of complications was similar for the two groups, the number of CLAK events that led to termination were 16 versus 5 for the medium-Dk and high-Dk groups, respectively. This suggests that the type of adverse response or the inability to reverse an adverse event was different for the group being exposed to the lower oxygen dose. The level of oxygen available to the cornea has a significant impact on maintaining successful RGP extended contact lens wear, but not on the initial onset of CLAK. The number of clinical events leading to termination was substantially higher for the medium Dk group, which suggests that corneal hypoxia is an important factor in the development of CLAK. Although overnight contact lens wear should be recommended with caution and carefully monitored for early detection of ocular complications, it appears that high-Dk RGP lenses can be a safe and effective treatment for correction of refractive error for most individuals who can adapt to EW.


    Indian Academy of Sciences (India)

    Subject Index. Variation of surface electric field during geomagnetic disturbed period at Maitri, Antarctica. 1721. Geomorphology. A simple depression-filling method for raster and irregular elevation datasets. 1653. Decision Support System integrated with Geographic. Information System to target restoration actions in water-.

  12. Surface and Sliding Wear Behaviour of Different Coatings and Steels

    Directory of Open Access Journals (Sweden)

    Vera-Cárdenas E.E.


    Full Text Available In this work, the sliding wear behaviour of the coatings TiN, CrN and WC/C applied on steel substrates was studied using a reciprocating wear test machine. All tests were carried out in dry conditions, at room temperature (20-23 C and 45% - 50% relative humidity. The average sliding velocity was 0.08 m/s and an amplitude of 2 mm was used. The applied loads were 11.76 N (Po = 1.74 GPa and 7.84 N (Po = 1.52 GPa. Optical microscopy was used to observe the characteristics of wear scars and spalls and possible causes of their formation. The variation of the friction coefficient against the number of cycles was obtained. This was used to determine more precisely the time (number of cycles where the coating presented the first signs of wear, in addition Energy Dispersive X-ray analysis (EDS was performed, as well as Scanning Electron Microscopy (SEM and hardness tests on the wear traces, which reinforced the previous observations. Thus it was possible to know the wear life of different coatings and possible causes of variation. Increasing the load was an important factor in the variation of wear life results. But it is also important to consider other factors such as surface roughness and thickness of coatings.

  13. Enamel erosion and mechanical tooth wear in medieval Icelanders. (United States)

    Richter, Svend; Eliasson, Sigfus Thor


    The Icelandic Sagas are an important source of information on the way of life and diet habits in Iceland and possibly other Nordic countries 1000 years ago. Archaeological human skull material worldwide has revealed extensive tooth wear, with the main cause believed to be coarse diet. From a graveyard near volcano Hekla, 66 skeletons dated from before 1104 were excavated. The purpose of this study was to determine the main causes of tooth wear in Icelanders 1000 years ago. Forty-nine skulls were available for research. Two methods were used to evaluate tooth wear and seven for age estimation. An attempt was made to determine the main causes of tooth wear in the light of likely diet and beverage consumption according to a computer search on food and drink customs described in the Icelandic Sagas. Tooth wear was extensive in all groups, increasing with age. The highest score was on first molars, with no difference between sexes. It had all the similarities seen in wear from coarse diet. In some instances it had similar characteristics to those seen in erosion in modern Icelanders consuming excessive amounts of soft drinks. According to the Sagas, acidic whey was a daily drink and used for preservation of food in Iceland until recently. Since acidic whey has considerably high dental erosive potential, it is postulated that consumption of acidic drinks and food, in addition to a coarse and rough diet, played a significant role in the dental wear of ancient Icelanders.

  14. Ferrography Wear Particles Image Recognition Based on Extreme Learning Machine

    Directory of Open Access Journals (Sweden)

    Qiong Li


    Full Text Available The morphology of wear particles reflects the complex properties of wear processes involved in particle formation. Typically, the morphology of wear particles is evaluated qualitatively based on microscopy observations. This procedure relies upon the experts’ knowledge and, thus, is not always objective and cheap. With the rapid development of computer image processing technology, neural network based on traditional gradient training algorithm can be used to recognize them. However, the feedforward neural network based on traditional gradient training algorithms for image segmentation creates many issues, such as needing multiple iterations to converge and easy fall into local minimum, which restrict its development heavily. Recently, extreme learning machine (ELM for single-hidden-layer feedforward neural networks (SLFN has been attracting attentions for its faster learning speed and better generalization performance than those of traditional gradient-based learning algorithms. In this paper, we propose to employ ELM for ferrography wear particles image recognition. We extract the shape features, color features, and texture features of five typical kinds of wear particles as the input of the ELM classifier and set five types of wear particles as the output of the ELM classifier. Therefore, the novel ferrography wear particle classifier is founded based on ELM.

  15. Relationship of engine bearing wear and oil rheology

    Energy Technology Data Exchange (ETDEWEB)

    Olson, D.H.


    Engine wear tests were conducted, using two different engine designs, with single and multigrade engine oils. In one engine there was a significant reduction in bearing wear when multigrade oils were used. For the other engine there was evidence of less bearing wear when multigrade oils were used. In both engines correlations were found among bearing wear, high-temperature high-shear-rate viscosity and oil elasticity. It has been shown that the minimum oil film thickness measured for the front main bearing in an operating engine is related to both oil viscosity and elasticity for multigrade oils. The study presented here is an attempt to extend that work to determine if the same oil rheological parameter can be used to establish a correlation to engine journal bearing wear. Two different engines were used and wear was measured for connecting rod big-ends bearings and main bearings. The results ranged from excellent to poor depending on the engine and bearing location within each engine. Despite the limited success in establishing correlations among the oil rheological properties and bearing wear, the results are being presented in the interest of stimulating further work in this important area.

  16. Effect of wearing an N95 filtering facepiece respirator on superomedial orbital infrared indirect brain temperature measurements. (United States)

    DiLeo, Travis; Roberge, Raymond J; Kim, Jung-Hyun


    To determine any effect of wearing a filtering facepiece respirator on brain temperature. Subjects (n = 18) wore a filtering facepiece respirator (FFR) for 1 h at rest while undergoing infrared thermography measurements of the superomedial periobital region of the eye, a non-invasive indirect method of brain temperature measurements we termed the superomedial orbital infrared indirect brain temperature (SOIIBT) measurement. Temperature of the facial skin covered by the FFR, infrared temperature measurements of the tympanic membrane and superficial temporal artery region were concurrently measured, and subjective impressions of thermal comfort obtained simultaneously. The temperature of the skin under the FFR and subjective impressions of thermal discomfort both increased significantly. The mean tympanic membrane temperature did not increase, and the superficial temporal artery region temperature decreased significantly. The SOIIBT values did not change significantly, but subjects who switched from nasal to oronasal breathing during the study (n = 5) experienced a slight increase in the SOIIBT measurements. Wearing a FFR for 1 h at rest does not have a significant effect on brain temperatures, as evaluated by the SOIIBT measurements, but a change in the route of breathing may impact these measurements. These findings suggest that subjective impressions of thermal discomfort from wearing a FFR under the study conditions are more likely the result of local dermal sensations rather than brain warming.

  17. Accommodative Behavior of Eyes Wearing Aspheric Single Vision Contact Lenses. (United States)

    Altoaimi, Basal H; Almutairi, Meznah S; Kollbaum, Pete; Bradley, Arthur


    Wearing aspheric contact lenses adds significant amounts of negative spherical aberration (SA). Also, when accommodated and converged to near targets, pupil size shrinks and SA shift from positive to more negative direction. Interestingly, in this study, pupil miosis was fully or partially able to compensate for the additional accommodation-induced negative SA. The present study aims to examine the accommodative response characteristics of young eyes fit with aspheric single vision contact lenses (SVCLs) that add significant negative SA to the eye responding to a wide range of accommodation stimuli. Using a Shack-Hartmann aberrometer, the accommodation behavior in eight young adult eyes (mean age and spherical equivalent is 27.25 ± 2.05 years and -1.75 ± 1.80D, respectively) was measured while subjects fixated binocularly and monocularly 20/40 letter E, which were moved from 2 m to 20 cm (0.5 to 5D) in 0.25D steps. Using natural pupils, refractive state was defined using three standard criteria: the dioptric power that (1) minimized the root mean square error (minRMS), (2) best-fit paraxial, and (3) provided the peak image quality (peak IQ). Wearing aspheric lenses with negative SA shifts the mean SA of the unaccommodated eyes from +0.05 μm (eyes only) to -0.029 μm (eyes + SVCL) and increases the negative SA for the eye + lens when accommodating from -0.029 to -0.07 μm for natural pupils. Aberration changes with accommodation were attenuated by the accommodative pupil miosis, which reduced binocular viewing pupil diameters from 3.9 to 3.3 mm. This alteration of the typical SA levels by the aspheric SVCL did not prevent accurate accommodation (mean ± standard deviation accommodative lag under binocular viewing were -0.08 ± 0.12D, -0.38 ± 0.12D, and -0.26 ± 0.08D for paraxial, minRMS, and peak IQ, respectively). These data clearly show that aspheric contact lenses designed to correct some or all of the unaccommodated eye's positive SA do not interfere with

  18. Clinical assessment of enamel wear caused by monolithic zirconia crowns. (United States)

    Stober, T; Bermejo, J L; Schwindling, F S; Schmitter, M


    The purpose of this study was to measure enamel wear caused by antagonistic monolithic zirconia crowns and to compare this with enamel wear caused by contralateral natural antagonists. Twenty monolithic zirconia full molar crowns were placed in 20 patients. Patients with high activity of the masseter muscle at night (bruxism) were excluded. For analysis of wear, vinylpolysiloxane impressions were prepared after crown incorporation and at 6-, 12-, and 24-month follow-up. Wear of the occlusal contact areas of the crowns, of their natural antagonists, and of two contralateral natural antagonists (control teeth) was measured by use of plaster replicas and a 3D laser-scanning device. Differences of wear between the zirconia crown antagonists and the control teeth were investigated by means of two-sided paired Student's t-tests and linear regression analysis. After 2 years, mean vertical loss was 46 μm for enamel opposed to zirconia, 19-26 μm for contralateral control teeth and 14 μm for zirconia crowns. Maximum vertical loss was 151 μm for enamel opposed to zirconia, 75-115 μm for control teeth and 60 μm for zirconia crowns. Statistical analysis revealed significant differences between wear of enamel by zirconia-opposed teeth and by control teeth. Gender, which significantly affected wear, was identified as a possible confounder. Monolithic zirconia crowns generated more wear of opposed enamel than did natural teeth. Because of the greater wear caused by other dental ceramics, the use of monolithic zirconia crowns may be justified. © 2016 John Wiley & Sons Ltd.

  19. The Effect of Shaping Technic toward the Ability of Wearing T-Shirt for Child with Intelectual Disability

    Directory of Open Access Journals (Sweden)

    gayatri hardianti


    Full Text Available The objective of study is to describe skill of shirt wearing before and after intervention and describe effect shaping technique towards skill of shirt wearing for intellectual disability. Method used is single-subject research with A-B-A design. The subject was a child with intellectual disability Grade I of SDLB. Analysis of data used was and inter-condition. Results showed that the effect of shaping techniques towards skills of shirt wearing child with intellectual disability. The conclusion that there is effect shaping techniques toward skill of shirt wearing intellectual disability. Suggestions include provide learning approaches variety, parents expected to cooperate in developing independence of intellectual disability, require fundamental research. Tujuan penelitian ini adalah untuk mendeskripsikan keterampilan memakai kemeja anak sebelum dan setelah diberikan intervensi dan pengaruh teknik shaping terhadap keterampilan memakai kemeja anak tunagrahita. Metode penelitian adalah eksperimen subjek tunggal dengan desain A-B-A. Subjek adalah anak tunagrahita ringan kelas 1 SDLB. Analisis data dengan menggunakan analisis dalam kondisi dan antar kondisi. Hasil penelitian menunjukkan adanya pengaruh teknik shaping terhadap keterampilan memakai kemeja anak tunagrahita. Kesimpulan penelitian adalah terdapat pengaruh antara teknik shaping terhadap keterampilan memakai kemeja anak tunagrahita. Saran penelitian berikan variasi pendekatan pembelajaran, orang tua diharapkan bekerjasama dalam mengembangkan kemandirian anak, perlu penelitian mendasar dalam pembelajaran bina diri.

  20. Improving Rail Wear and RCF Performance using Laser Cladding


    Lewis, S.R.; Fretwell-Smith, S.; Goodwin, P.S.; Smith, L.; Lewis, R.; Aslam, M.; Fletcher, D.I.; Murray, K.; Lambert, R.


    Laser cladding has been considered as a method for improving the wear and RCF performance of standard grade rail. This paper presents results of small scale tests carried out to assess the wear and RCF performance of rail which had been laser clad. Using the laser cladding process premium metals can be deposited on to the working surface of standard rail with the aim of enhancing the wear and RCF life of the rail. Various laser clad samples were tested using a twin-disc method. The candidate ...

  1. Lubricity Additives and Wear with DME in Diesel Injection Pumps

    DEFF Research Database (Denmark)

    Nielsen, Kasper; Sorenson, Spencer C.


    In recent years it has been demonstrated that Dimethyl Ether (DME) possess many characteristics that could make it a successful alternative to diesel in the next century. High wear of the fuel injection system has been reported. This is caused by lack of natural protective constituents of Dimethyl...... wear of standard diesel jerk pump plungers elements were made with weight measurements, diameter measurements, 2-D and 3-D surface roughness measurements, and photography by a Michelson interferometer. Several lubricity additives were tested, but none reduced wear levels to those for diesel fuel...

  2. Evaluating and comparison between wear behavior of dental Amalgam

    Directory of Open Access Journals (Sweden)

    Fathi MH


    Full Text Available Wear characteristics of dental amalgams were investigated by in vivo and in vitro tests. Wear"nof dental amalgam was studied and evaluated using a three - body abrasion test and Pin-On-Disk"nmethod. Porcelain was used for preparing disk and materials such as toothpaste, artificial saliva and"nnaturally saliva were used as the third material that was contributed in tribologic system"nThe results showed that effects of various toothpastes on the wear of dental amalgam are considerably"ndifferent and size, shape and chemical composition of amalgam are important too.

  3. Conscious hypnosis as a method for patient motivation in cervical headgear wear--a pilot study. (United States)

    Trakyali, Göksu; Sayinsu, Korkmaz; Müezzinoğlu, Ali Eşref; Arun, Tülin


    The aim of the present study was to assess the efficiency of conscious hypnosis on patient cooperation. The subjects were 30 patients (14 females and 16 males) with a skeletal Class II division 1 malocclusion, divided into two equal groups, a control and a study group. The mean age was 10.78 +/- 1.06 years for the hypnosis, and 10.07 +/- 1.09 years for the control group. Both groups were treated with cervical headgear containing a timer module. The patients were also asked to record their actual wear time on timetables. The hypnosis group patients were motivated with conscious hypnosis while the control group were given verbal motivation by their orthodontist. The timer modules were read at every visit and compared with the timetables. Analysis of variance was used to determine the differences in measurements at each time point. For comparison of the groups, an independent t-test was used. A statistically significant decrease (P headgear wear was observed in the control group from the first to the sixth month; however, the difference in the hypnosis group was not significant. This result indicates that conscious hypnosis is an effective method for improving orthodontic patient cooperation. There was a low correlation between actual headgear wear indicated by the patient and that recorded by the timing modules, which showed that, timetables are not consistent tools for measuring patient cooperation.

  4. The wearing of hydrophilic contact lenses aboard a commercial jet aircraft: I. Humidity effects on fit. (United States)

    Eng, W G; Harada, L K; Jagerman, L S


    The increasing use of hydrophilic (soft) lenses in the United States hs prompted interest in the clinical investigation of these lenses under various wearing conditions. Any factor causing lens dehydration during wear may affect lens performance and ultimately cause eye discomfort. The purpose of this study was to evaluate the environmental conditions in the aircraft cabin and to observe any changes in the fit of the hydrophilic lenses that might occur during flight. A "laboratory" for testing was set up aboard a World Airways DC-10 on a scheduled round trip between Oakland, California and Honolulu, Hawaii. A keratometer was used to assess lens fit of seven subjects who were wearing hydrophilic lenses. The efficacy of using a soft lens hydrating solution on the fit of the lens was evaluated, but will also be evaluated in a future paper. Atmospheric pressure, humidity, and temperature measurements were recorded throughout the inflight study. The results showed that a decline in cabin humidity from at least 47% to 11% occurred within 30 min of takeoff. Although previous reports have indicated that there are a number of environmental factors in the aircraft that contribute to eye discomfort for lens wearers, this study indicates that low cabin humidity is possibly the most significant factor.

  5. Maximal stress test performance while wearing a self-contained breathing apparatus

    Energy Technology Data Exchange (ETDEWEB)

    Raven, P.B.; Davis, T.O.; Shafer, C.L.; Linnebur, A.C.


    Fifteen adult male volunteers (mean age = 31.0 years; eight non-smokers and seven smokers) carried out a Bruce protocol maximal treadmill stress test under four separate conditions. These four conditions were (1) without Scott Air Pak (SAP) respirator; (2) with SAP respirator apparatus but not wearing face mask; (3) with SAP apparatus, wearing face mask in ''demand'' breathing mode; and (4) with SAP respirator apparatus, wearing face mask in ''pressure-demand'' breathing mode. The data indicate that the overriding factor in the approximately 20% decrement in work performance during conditions 2, 3, and 4 was related to the weight of the SAP respirator (15.8 kg), P < 0.05. Only during condition 3 did eight of 15 subjects report lack of air as one reason for termination. Conditions 3 and 4 resulted in a significant decrease in T/sub Fore/ (2.5/sup 0/C) and was primarily related to the decreased T/sub insp/ which reached a maximum decrement of 9.7/sup 0/C. Under all conditions the smokers' work time was significantly less than nonsmokers, P < 0.05.

  6. Effect of complete denture wearing on deglutition time: a cine-magnetic resonance imaging study. (United States)

    Gokce, H S; Gokce, S M; Akin, E; Bulakbasi, N; Akyol, M


    Purpose of the study was to evaluate the effect of complete denture wearing on deglutition time (DT), hyoid bone and larynx movements in edentulous patients with real-time balanced turbo field echo cine-magnetic resonance imaging. Subjects were examined by cine-magnetic resonance imaging in supine position during swallowing water. Two sets of images for 23 edentulous (with/without wearing complete dentures) and one for 23 dentulous patients were obtained. Radiographic outputs representing three consecutive deglutition stages (oral, pharyngeal and oesophageal) were provided to perform measurements. Deglutition time significantly increased when edentulous patients wore their dentures (mean 0·75 s increased to 1·17 s), whereas dentulous patients' DT was about 0·91 s (P ≤ 0.05). The duration of deglutition is crucial because prolonged pharyngeal transit times increases the risk of aspiration. Within the limitations of the study, complete denture wearing could increase the shortened DT of the edentulous patients. © 2011 Blackwell Publishing Ltd.

  7. Hard contact lens wear and the risk of acquired blepharoptosis: a case-control study. (United States)

    Kitazawa, Takeshi


    Since there are increasing numbers of patients with blepharoptosis who have a history of wearing contact lenses, we attempted to estimate the risk of developing ptosis from wearing hard contact lenses. In an age-matched case-control study that was performed in a hospital in Japan, we compared the rate of hard contact lens users in ptosis cases with that in a control group and then estimated the odds ratio. The history of wearing hard contact lenses was significantly higher in patients (90.2%) versus controls (31.6%). Hard contact lens wearers had a 20 times increased risk of ptosis (odds ratio: 19.9; 95% confidence interval: 6.32-62.9) compared with the nonwearing subjects. This study indicated that there was a significant association between hard contact lenses and blepharoptosis. Because of both the prevalence of use and the aging of the population, contact lens-induced blepharoptosis is no longer just a problem for young and middle-aged people with myopia but also for the elderly population.

  8. Automated visual inspection of brake shoe wear (United States)

    Lu, Shengfang; Liu, Zhen; Nan, Guo; Zhang, Guangjun


    With the rapid development of high-speed railway, the automated fault inspection is necessary to ensure train's operation safety. Visual technology is paid more attention in trouble detection and maintenance. For a linear CCD camera, Image alignment is the first step in fault detection. To increase the speed of image processing, an improved scale invariant feature transform (SIFT) method is presented. The image is divided into multiple levels of different resolution. Then, we do not stop to extract the feature from the lowest resolution to the highest level until we get sufficient SIFT key points. At that level, the image is registered and aligned quickly. In the stage of inspection, we devote our efforts to finding the trouble of brake shoe, which is one of the key components in brake system on electrical multiple units train (EMU). Its pre-warning on wear limitation is very important in fault detection. In this paper, we propose an automatic inspection approach to detect the fault of brake shoe. Firstly, we use multi-resolution pyramid template matching technology to fast locate the brake shoe. Then, we employ Hough transform to detect the circles of bolts in brake region. Due to the rigid characteristic of structure, we can identify whether the brake shoe has a fault. The experiments demonstrate that the way we propose has a good performance, and can meet the need of practical applications.

  9. Orthoptic indications for contact lens wear. (United States)

    Evans, Bruce J W


    Orthoptic anomalies are prevalent: they are encountered in at least 5% of patients seen in a typical primary eyecare practice. Several cases are reviewed that highlight the role of contact lenses in treating orthoptic anomalies. In particular, contact lenses are the preferred optical approach to the correction of anisometropia, and it is often argued that anisometropia should be corrected as young as possible. However, fitting contact lenses to patients, particularly children, with anisometropic amblyopia has been problematic because there is no immediate binocular acuity improvement when the contact lenses are inserted which reduces patient motivation. Continuous wear with silicone hydrogels represents a breakthrough for these cases and some illustrative case studies are given. The visual deficit in amblyopia can be reduced in some cases solely by fitting contact lenses, without the need for occlusion therapy. Other orthoptic uses of contact lenses are reviewed including: correcting motor deviations, occlusion, and infantile onset nystagmus. It is concluded that there are orthoptic anomalies where contact lenses are the preferred mode of correction. It is in patients' best interest for practitioners to discuss contact lenses in these cases.

  10. Non-compliance in contact lens wear. (United States)

    Claydon, B E; Efron, N


    Non-compliance is emerging as a critical issue in the contact lens field. This problem has been studied at depth in general health care situations and is seen as the responsibility of both practitioner and patient (client) working in a health care partnership. The contact lens practitioner and patient present a specific case for the study of non-compliance in areas such as hygiene, solution use, appointment attendance and wearing times. From 40 to 91% of contact lens patients have been reported as non-complaint in the use of recommended care and maintenance regimens and many of these are confused or ignorant about their behaviour. In order to arrive at a general set of conclusions from the studies published to date, it is important to understand the methodology of each study, it purpose, the definition of non-compliance used and the way the results were analysed and described. This review summarizes the research into non-compliance in the contact lens field to data. A set of general conclusions is drawn and a model for compliance in the context of contact lens practice is proposed.

  11. Sunglasses- and photochromic lens-wearing patterns in spectacle and/or contact lens-wearing individuals. (United States)

    Glavas, Ioannis P; Patel, Sarit; Donsoff, Irene; Stenson, Susan


    To determine differences in wearing patterns of sunglasses and/or photochromic lenses in spectacle and contact lens wearers, to assess patient awareness of the indications for the use of tinted lenses, and to identify wearers' lens tint preferences. A total of 100 individuals wearing some combination of contact lenses and spectacles participated in a survey questionnaire composed of 14 questions. Participants were asked if they used sunglasses/photochromic lenses, why they used them, their preferred lens tints, and temporal and seasonal patterns of use. They were also queried on their awareness of the potential adverse effects of ultraviolet radiation (UVR) exposure on the health of the eye and appropriate protective measures. Participants were categorized based on their use of spectacles and/or contact lenses. Demographic characteristics of sex and age were taken into account for the analysis. The data were imported and analyzed using commercial statistical analysis software. A total of 52% of the participants wore spectacles exclusively, while 48% wore some combination of spectacles and contact lenses. In the spectacle group, 36% and 20% wore sunglasses and photochromic lenses, respectively. In the contact lens group, 20% and 10% wore sunglasses and photochromic lenses, respectively. Overall gray was the preferred lens tint, especially in the younger age groups. Summer was the primary season for use of tinted lenses. Approximately one-third of the sample were not aware of the UVR protective properties of their eyewear. A total of 77% believed that UVR could be harmful to the eyes, but only a small percentage of the participants wore sunglasses or photochromic lenses specifically for UVR protection. There was no statistically significant difference (P = 0.07) for preference between sunglasses versus photochromic lenses and in seasonal patterns for tinted lens use among spectacles and contact lens wearers. Spectacle wearers (as well as contact lens wearers) used

  12. Standard test method for ranking resistance of plastics to sliding wear using block-on-ring wear test—cumulative wear method

    CERN Document Server

    American Society for Testing and Materials. Philadelphia


    1.1 This test method covers laboratory procedures for determining the resistance of plastics to sliding wear. The test utilizes a block-on-ring friction and wear testing machine to rank plastics according to their sliding wear characteristics against metals or other solids. 1.2 An important attribute of this test is that it is very flexible. Any material that can be fabricated into, or applied to, blocks and rings can be tested. Thus, the potential materials combinations are endless. In addition, the test can be run with different gaseous atmospheres and elevated temperatures, as desired, to simulate service conditions. 1.3 Wear test results are reported as the volume loss in cubic millimetres for the block and ring. Materials of higher wear resistance will have lower volume loss. 1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with it...

  13. Plasma powder coating of rods of hydraulic cylinders with white wear resistance cast iron

    Directory of Open Access Journals (Sweden)

    S. P. Nefedyev


    Full Text Available The article considers the features to form a structure and properties of Fe-C-Cr-V system coverings provided by the plasma and powder coating (build-up on the low carbon steel.It is shown that it is possible to restore a rod of hydraulic cylinders of small diameter by the plasma and powder coating. Thus, to avoid buckling and provide the built-up metal structure with the best wear resistance it is necessary to find a reasonable approach to a choice of the operation conditions to provide coating.The paper offers a way for efficient control of heat input at coating and a superheat value of the welding bath. It is noted that the coverings, which have been built up at the smallest heat input in a substrate, possess the best wear resistance, with a fusion zone formed with an austenitic crystallization interlayer.The paper defines consistent patterns to form a structure of coverings under various operation conditions of a plasma and powder coating. It shows the influence of the cooling speed after built-up metal crystallization on the formation of covering structure components.The paper formulates requirements for operation conditions of plasma and powder coating to provide coverings to be subjected to shock and abrasive wear, and shows the influence of additional heat treatment on formation of structure and properties of the built-up metal.The article under review meets available lacks in studying high-carbon chrome-vanadium coverings and is useful for scientists, graduates, and students investigating the wear resistance coating materials and effective methods for their deposition.

  14. Clinical and laboratory surface finishing procedures for zirconia on opposing human enamel wear: A laboratory study. (United States)

    Chong, Bevan J; Thangavel, Arun K; Rolton, Shane B; Guazzato, Massimiliano; Klineberg, Iven J


    To investigate the effect of laboratory and clinical finishing procedures for zirconia on antagonistic enamel wear. Forty-eight yttria-tetragonal partially stabilised zirconia (Y-TZP) specimens were prepared and divided into four groups according to their surface preparation: laboratory polished (LP); laboratory polished and glazed (G); clinically adjusted (CA); and clinically adjusted and repolished (CAR). Enamel opposing enamel was used as a control. Pre-testing surface roughness for each group was determined using contact profilometry. Two-body wear resistance tests were conducted using a masticatory simulator. Enamel specimens were subjected to 120,000 cycles in distilled water (frequency 1.6 Hz, loading force of 49 N). Volumetric and vertical enamel losses were measured by superimposition of pre- and post-testing images using a three-dimensional laser scanner and software analysis. Scanning electron microscopy was used for qualitative surface analysis of pre- and post-testing zirconia and enamel surfaces. One-way ANOVA and multiple comparisons with Bonferroni corrections were used for statistical analysis at a significance level of α=0.05. There was no statistical difference in volumetric and vertical enamel loss between CAR, G and LP. CAR produced statistically significantly less volumetric enamel loss compared with CA and control, and statistically significantly less vertical enamel loss compared with CA. Volumetric and vertical enamel loss were highly correlated in all groups. Enamel wear by clinically ground zirconia is comparable to that of opposing enamel surfaces and greater than clinically repolished zirconia. Repolishing of zirconia restorations following clinical adjustment with diamond burs is effective in reducing antagonistic enamel wear. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. To wear or not to wear: current contact lens use in the Royal Canadian Mounted Police. (United States)

    Wells, G A; Brown, J J; Casson, E J; Easterbrook, M; Trottier, A J


    The Canadian Ophthalmological Society was asked by the Royal Canadian Mounted Police (RCMP) and the Canadian Human Rights Commission to render an opinion on the acceptability of contact lenses as a reasonable accommodation to the uncorrected visual acuity standard. Survey by mailed questionnaire. Canada. All RCMP general duty constables with a visual acuity code of V3, V4, V5 or V6 (n = 348) and a random sample of approximately 25% of the constables with an acuity code of V2 (n = 809). Of the 1040 questionnaires returned, 1037 were usable (final response rate 89.6%). Of the 1037 respondents 316 were in the V3 to V6 group and 721 were in the V2 group. Reported frequency of problems with spectacles or contact lenses, weighted according to sampling fraction. A total of 934 respondents indicated that they used some form of visual acuity correction while on duty; of the 934, 360 reported that they wore contact lenses at least some of the time. Approximately 75% of the spectacle wearers reported having to remove their spectacles because of fogging or rain. Although contact lens dislogement or fogging (21.2%) was less frequent than spectacle dislogement (59.2%), 35.4% of the contact lens wearers reported that they were unable to wear their lenses because of irritation on at least one occasion in the previous 2 years; the median length of time was 3.14 days. When the additional amount of time due to other causes is factored in, it is clear that contact lens users wear spectacles for substantial periods while on duty. Not only are RCMP general duty constables who usually wear contact lenses likely to have to wear spectacles at some time, but it is also possible that they will have to remove their spectacles and function in an uncorrected state in critical situations. Thus, altering the current standard to allow the use of contact lenses as a reasonable accommodation would not ensure effective and safe job performance.

  16. Corneal Swelling with Cosmetic etafilcon A Lenses versus No Lens Wear (United States)

    Moezzi, Amir M.; Varikooty, Jalaiah; Schulze, Marc; Ngo, William; Lorenz, Kathrine Osborn; Boree, Danielle; Jones, Lyndon W.


    ABSTRACT Purpose To determine if the use of pigments or adding polyvinyl pyrrolidone during the fabrication of 1-DAY ACUVUE DEFINE (AD) brand contact lenses impacts open-eye corneal swelling compared with no lens wear (NLW). Methods A partial double-masked, randomized, bilateral crossover study was conducted in 24 Asian subjects using AD, 1-DAY ACUVUE DEFINE with Lacreon (ADL), NLW, and a control lens with no tint (1-DAY ACUVUE MOIST [AM]). Central corneal thickness was measured before insertion and immediately after removal after 8 ± 1 h of open-eye wear using an optical pachymeter in one eye. Corneal thickness along a 10-mm cord was measured in the contralateral eye using the Visante optical coherence tomographer (OCT). Corneal swelling was tested for noninferiority using a 5% margin. The endothelial bleb response was measured at baseline and 20 min after lens insertion using specular microscopy. Subjective grading of corneal staining and limbal/bulbar hyperemia were also monitored. Results After 8 ± 1 h of open-eye wear, central corneal swelling across the study lenses with either optical pachymeter or OCT methods was negligible. Peripheral corneal swelling least-square mean differences with OCT were −0.03% (95% confidence interval [95% CI], −0.65 to 0.58%) and −0.26% (95% CI, −0.87 to 0.36%) between AD and ADL and the control lens (AM), respectively, and 1.67% (95% CI, 1.06 to 2.29%) and 1.45% (95% CI, 0.84 to 2.06%) between AD and ADL and NLW, respectively. No endothelial blebs were observed. No clinically significant differences were distinguished between the lenses and NLW for corneal staining and limbal/bulbar hyperemia. Conclusions After 8 ± 1 h of open-eye wear, central and peripheral corneal swelling along the horizontal meridian with AD, ADL, AM, and NLW were equivalent. These results confirm that the addition of polyvinyl pyrrolidone or pigments to etafilcon A to obtain a limbal ring design have no impact on corneal swelling or limbal

  17. How Do Stars Gain Their Mass? A JCMT/SCUBA-2 Transient Survey of Protostars in Nearby Star-forming Regions (United States)

    Herczeg, Gregory J.; Johnstone, Doug; Mairs, Steve; Hatchell, Jennifer; Lee, Jeong-Eun; Bower, Geoffrey C.; Chen, Huei-Ru Vivien; Aikawa, Yuri; Yoo, Hyunju; Kang, Sung-Ju; Kang, Miju; Chen, Wen-Ping; Williams, Jonathan P.; Bae, Jaehan; Dunham, Michael M.; Vorobyov, Eduard I.; Zhu, Zhaohuan; Rao, Ramprasad; Kirk, Helen; Takahashi, Satoko; Morata, Oscar; Lacaille, Kevin; Lane, James; Pon, Andy; Scholz, Aleks; Samal, Manash R.; Bell, Graham S.; Graves, Sarah; Lee, E.'lisa M.; Parsons, Harriet; He, Yuxin; Zhou, Jianjun; Kim, Mi-Ryang; Chapman, Scott; Drabek-Maunder, Emily; Chung, Eun Jung; Eyres, Stewart P. S.; Forbrich, Jan; Hillenbrand, Lynne A.; Inutsuka, Shu-ichiro; Kim, Gwanjeong; Kim, Kyoung Hee; Kuan, Yi-Jehng; Kwon, Woojin; Lai, Shih-Ping; Lalchand, Bhavana; Lee, Chang Won; Lee, Chin-Fei; Long, Feng; Lyo, A.-Ran; Qian, Lei; Scicluna, Peter; Soam, Archana; Stamatellos, Dimitris; Takakuwa, Shigehisa; Tang, Ya-Wen; Wang, Hongchi; Wang, Yiren


    Most protostars have luminosities that are fainter than expected from steady accretion over the protostellar lifetime. The solution to this problem may lie in episodic mass accretion—prolonged periods of very low accretion punctuated by short bursts of rapid accretion. However, the timescale and amplitude for variability at the protostellar phase is almost entirely unconstrained. In A James Clerk Maxwell Telescope/SCUBA-2 Transient Survey of Protostars in Nearby Star-forming Regions, we are monitoring monthly with SCUBA-2 the submillimeter emission in eight fields within nearby (< 500 pc) star-forming regions to measure the accretion variability of protostars. The total survey area of ˜1.6 deg2 includes ˜105 peaks with peaks brighter than 0.5 Jy/beam (43 associated with embedded protostars or disks) and 237 peaks of 0.125-0.5 Jy/beam (50 with embedded protostars or disks). Each field has enough bright peaks for flux calibration relative to other peaks in the same field, which improves upon the nominal flux calibration uncertainties of submillimeter observations to reach a precision of ˜2%-3% rms, and also provides quantified confidence in any measured variability. The timescales and amplitudes of any submillimeter variation will then be converted into variations in accretion rate and subsequently used to infer the physical causes of the variability. This survey is the first dedicated survey for submillimeter variability and complements other transient surveys at optical and near-IR wavelengths, which are not sensitive to accretion variability of deeply embedded protostars.

  18. Hardfacing materials used in valves for seating and wear surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Knecht, W.G.


    Most valves and essentially all critical service valves utilize hardfacing materials for seating and wear surfaces to minimize wear and galling. The type of hardfacing materials used, the methods of deposition, and the quality of the final product all contribute to the wear characteristics, required operating force, and life of the final product. Over the last forty years the most prevalent hardfacing materials furnished to the commercial nuclear industry consisted of cobalt base and nickel base materials. In the last several years there has been extensive development and evaluation work performed on iron base hardfacing materials. This presentation will address the wear characteristics of the various materials and the importance of consistent quality of deposited materials necessary to achieve optimum product performance and longevity.

  19. Severe wear behaviour of alumina balls sliding against diamond ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 39; Issue 2. Severe wear behaviour of alumina balls sliding against diamond ceramic coatings. ANURADHA JANA NANDADULAL DANDAPAT MITUN DAS VAMSI KRISHNA BALLA SHIRSHENDU CHAKRABORTY RAJNARAYAN SAHA AWADESH KUMAR MALLIK.


    Directory of Open Access Journals (Sweden)

    K. E. Baranovskij


    Full Text Available Casting of wear-resistant chrome cast irons in combined molds and iron chills is studied. Application of these ways of casting results in blending of carbides and increasing of hardness of castings.

  1. Evaluating the accuracy of wear formulae for acetabular cup liners. (United States)

    Wu, James Shih-Shyn; Hsu, Shu-Ling; Chen, Jian-Horng


    This study proposes two methods for exploring the wear volume of a worn liner. The first method is a numerical method, in which SolidWorks software is used to create models of the worn out regions of liners at various wear directions and depths. The second method is an experimental one, in which a machining center is used to mill polyoxymethylene to manufacture worn and unworn liner models, then the volumes of the models are measured. The results show that the SolidWorks software is a good tool for presenting the wear pattern and volume of a worn liner. The formula provided by Ilchmann is the most suitable for computing liner volume loss, but is not accurate enough. This study suggests that a more accurate wear formula is required. This is crucial for accurate evaluation of the performance of hip components implanted in patients, as well as for designing new hip components.

  2. Friction and wear methodologies for design and control

    CERN Document Server

    Straffelini, Giovanni


    This book introduces the basic concepts of contact mechanics, friction, lubrication, and wear mechanisms, providing simplified analytical relationships that are useful for quantitative assessments. Subsequently, an overview on the main wear processes is provided, and guidelines on the most suitable design solutions for each specific application are outlined. The final part of the text is devoted to a description of the main materials and surface treatments specifically developed for tribological applications and to the presentation of tribological systems of particular engineering relevance. The text is up to date with the latest developments in the field of tribology and provides a theoretical framework to explain friction and wear problems, together with practical tools for their resolution. The text is intended for students on Engineering courses (both bachelor and master degrees) who must develop a sound understanding of friction, wear, lubrication, and surface engineering, and for technicians or professi...

  3. Wear properties of nanosilica filled epoxy polymers and FRP composites

    Directory of Open Access Journals (Sweden)

    A. Jumahat


    Full Text Available This paper is aimed to determine the wear properties of nanosilica filled epoxy polymers and FRP composites. Woven fiberglass has been deployed as the reinforcement material. The fibers were mixed with three different percentages of nanosilica-modified epoxy resin, i.e: 5wt%; 13wt%; 25wt%, in order to fabricate the desired samples of FRP composites. The effect of nanosilica on wear properties was evaluated using dry sliding wear and slurry tests. The results show that increasing the amount of nanosilica content has reduced the amount of accumulated mass loss. It was found that the FRP laminates with 25wt% of nanosilica have the highest wear resistance. The nanosilica filled fiber reinforced polymer composites have a high potential in tribological application such as ball bearing housing and snow sleds.

  4. Clinical studies of dental erosion and erosive wear

    National Research Council Canada - National Science Library

    Huysmans, M.C.D.N.J.M; Chew, H.P; Ellwood, R.P


    We define erosion as a partial demineralisation of enamel or dentine by intrinsic or extrinsic acids and erosive tooth wear as the accelerated loss of dental hard tissue through the combined effect...

  5. RGW: Goodman-Weare Affine-Invariant Sampling (United States)

    Mantz, Adam B.


    RGW is a lightweight R-language implementation of the affine-invariant Markov Chain Monte Carlo sampling method of Goodman & Weare (2010). The implementation is based on the description of the python package emcee (ascl:1303.002).

  6. Mitigation of wear damage by laser surface alloying technique

    CSIR Research Space (South Africa)

    Adebiyi, ID


    Full Text Available , and alloys having these specific properties are usually very expensive and their use drastically increases components and production costs. Moreover, the economic implications of wear, in form of detrimental effects – and waste, are severe. This includes...

  7. Wearing courses for unpaved roads in southern Africa: a review

    CSIR Research Space (South Africa)

    Netterberg, F


    Full Text Available The requirements of and some specifications for wearing courses for unpaved roads are reviewed. It is concluded that further development of specifications is required, and that there is probably great scope for improvement of our unpaved roads...

  8. Wear deformation of ordered Fe-Al intermetallic alloys

    Energy Technology Data Exchange (ETDEWEB)

    Maupin, H.E. (US Bureau of Mines, Albany Research Center, OR (United States)); Wilson, R.D. (US Bureau of Mines, Albany Research Center, OR (United States)); Hawk, J.A. (US Bureau of Mines, Albany Research Center, OR (United States))


    The Bureau of Mines conducted abrasive wear research on DO[sub 3] ordered and disordered Fe[sub 3]Al intermetallics. The effect of abrasion on these alloys was studied through mixroscopy, X-ray diffraction and hardness measurements. The region near the wear surface undergoes dynamic recrystallization, i.e. the original microstructural morphology of micron-size grains is replaced by one with nanosize grains. Abrasion of the Fe[sub 3]Al alloys also results in a loss of the DO[sub 3] ordering in the wear surface region. The bulk temperature rise of the specimen during abrasion was approximately 28 C which is insufficient to cause recrystallization in these alloys. Therefore, the flash temperature due to interface frictional heating is considered more important than the bulk temperature when considering dynamic recrystallization as the transformation mechanism in the near wear surface region. (orig.)

  9. Analysis of Wear Behavior of Thermoplastic Bio-Composite (United States)

    Bajpai, Pramendra Kumar; Chaudhary, Vijay


    In the present work, response surface methodology (RSM) has been used to model and predict the wear properties of Bio-composites fabricated in this study. Polished stainless steel counterface has been used to analyze the wear response of the bio-composite under dry contact condition. Three process variables namely applied sliding speed, normal load, and sliding distance were taken to investigate their effect on output response (specific wear rate). Statistical analysis was performed in the form of the analysis of variance (ANOVA) to analyze the significance and interaction of experimental parameters. The mathematical relationship between sliding wear input process parameters and output responses has been established to determine the values of output responses.

  10. 32 CFR 507.12 - Possession and wearing. (United States)


    ... PUBLIC RELATIONS MANUFACTURE AND SALE OF DECORATIONS, MEDALS, BADGES, INSIGNIA, COMMERCIAL USE OF... Force by any person not properly authorized to wear such device, or the use of any decoration, service... Secretary of the Air Force. ...

  11. Study of wear performance of deep drawing tooling (United States)

    Naranje, Vishal G.; Karthikeyan, Ram; Nair, Vipin


    One of the most common challenges for many of the mechanical engineers and also in the field of materials science is the issue of occurrences of wear of the material parts which is used in certain applications that involves such surface interactions. In this paper, wear behaviour of particular grade High Carbon High Chromium Steel and many most famously D2, H13, O1 known as the Viking steel has been studied, evaluated and analyzed under certain processing parameters such as speed, load, track diameter and time required for deep drawing process to know it’s the wear rate and coefficient of friction. Also, the significance of the processing parameters which is used for wear testing analysis is also examined.

  12. An Anthropological Perspective: Another Dimension to Modern Dental Wear Concepts

    Directory of Open Access Journals (Sweden)

    John A. Kaidonis


    Full Text Available For many years, research on tooth wear by dental academics has been diametrically opposite to that of anthropological research, with each discipline having a different understanding as to the nature of the wear processes. Dental focus revolved around preventive and restorative considerations while the anthropological focus was a biological understanding related to human evolution, diet, environment, form, and function and included all the craniofacial structures. Introducing the anthropological perspective into modern dentistry gives an insight into the “bigger picture” of the nature and extent of tooth wear. By combining anthropological evidence with clinical knowledge and experience, it is most likely to provide the best-informed and biologically based approach to the management of tooth wear in modern societies.

  13. Adverse events in allergy sufferers wearing contact lenses (United States)

    Urgacz, Agnieszka; Mrukwa, Ewa


    Allergy is the fifth leading chronic condition in industrialized countries among all ages, and the third most common chronic disease among children under 18 years old. Many of allergic patients also have problems with vision and want to improve their quality of life by wearing contact lenses. They are most frequently young and active individuals, for whom contact lenses provide greater convenience and more satisfying vision correction than spectacles. However, application of high quality and immunologically neutral products do not protect from allergic side reactions. Nowadays, eye-related allergy and contact lens wear concern larger and larger populations worldwide. The purpose of this review is to summarize the studies on ocular complications associated with wearing contact lenses. The article presents indications for allergic patients especially on the care system and wear schedule. PMID:26161062

  14. Friction and Wear Behavior of Selected Dental Ceramics (United States)

    Park, Jongee; Pekkan, Gurel; Ozturk, Abdullah

    The purpose of this study was to determine the friction coefficients and wear rates of six commercially available dental ceramics including IPS Empress 2 (E2), Cergo Pressable Ceramic (CPC), Cercon Ceram (CCS) and Super porcelain EX-3 (SPE). Bovine enamel (BE) was also tested as a reference material for comparison purposes. Samples of the dental ceramics were prepared according to the instructions described by the manufacturers in disk-shape with nominal dimensions of 12 mm × 2 mm. The wear tests were performed by means of a pin-on-disk type tribometer. The friction coefficients and specific wear rates of the materials were determined at a load of 10 N and rotating speed of 0.25 cm/s without lubrication. Surface morphology of the wear tracks was examined using a scanning electron microscope. Statistical analyses were made using one-way ANOVA and Turkey's HSD (P < 0.05).

  15. Tooth wear: prevalence and associated factors in general practice patients. (United States)

    Cunha-Cruz, Joana; Pashova, Hristina; Packard, J D; Zhou, Lingmei; Hilton, Thomas J


    To estimate the prevalence of tooth wear and to investigate factors associated with tooth wear in patients from general practices in the Northwest United States. Data on the diagnosis and treatment of oral diseases during the previous year were collected in a survey with a systematic random sample of patients (n= 1530) visiting general dentists from the Northwest Practice-based REsearch Collaborative in Evidence-based DENTistry (PRECEDENT) (n=80). Prevalence ratios (PRs) of moderate to severe occlusal and incisal tooth wear by patient characteristics were estimated using cluster-adjusted multiple binomial regression for adults (18+ years) and children/adolescents (3-17 years). For adults, the mean number of teeth with wear facets was 5.4 [95% confidence interval (CI) =4.6-6.2] and 51% of the adults had four or more teeth with wear. Participants 45-64 and 65+ years old were 1.3 (95% CI=1.1-1.6) and 1.4 (95% CI=1.1-1.8) times as likely to have 4+ teeth with moderate to severe wear facets as participants 18-44 years old. Adult males had a 20% (PR=1.2; 95% CI=1.1-1.4) higher prevalence of wear than adult females. Adults who were using, or had ever used occlusal splints had higher prevalence of tooth wear compared to those who never used such appliances (PR=1.3; 95% CI=1.0-1.5). Adults with any periodontal bone loss also had a 20% higher prevalence of wear than adults without periodontal disease (PR=1.2; 95% CI=1.0-1.4). For children/adolescents, the mean number of teeth with moderate to severe wear facets was 1.6 (95% CI=0.9-2.6) and 31% of the children had one or more teeth with wear facets. The adjusted prevalence ratio of tooth wear (1+ teeth with wear facets) for boys was 1.6 times as high (95% CI=1.1-2.4) as compared with girls. The prevalence of wear for children 12+ years old was 50% (PR=0.5; 95% CI=0.3-0.8) lower than that of children treatment, missing teeth, and race/ethnicity. Tooth wear is a prevalent condition in this population. Among adults, higher

  16. Corrosion and wear resistant metallic layers produced by electrochemical methods

    DEFF Research Database (Denmark)

    Christoffersen, Lasse; Maahn, Ernst Emanuel


    Corrosion and wear-corrosion properties of novel nickel alloy coatings with promising production characteristics have been compared with conventional bulk materials and hard platings. Corrosion properties in neutral and acidic environments have been investigated with electrochemical methods...

  17. Evaluation Of Saltstone Mixer Paddle Configuration For Improved Wear Resistance

    Energy Technology Data Exchange (ETDEWEB)

    Reigel, M. M.; Fowley, M. D.; Pickenheim, B. R.


    A soft metal with low wear resistance (6000 series aluminum), was used to minimize run time while maximizing wear rate. Two paddle configurations were tested, with the first four paddles after the augers replaced by the wear paddles. The first configuration was all flat paddles, with the first paddle not aligned with the augers and is consistent with present SPF mixer. The second configuration had helical paddles for the first three stages after the augers and a flat paddle at the fourth stage. The first helical paddle was aligned with the auger flight for the second configuration. The all flat paddle configuration wear rate was approximately double the wear rate of the helical paddles for the first two sets of paddles after the augers. For both configurations, there was little or no wear on the third and fourth paddle sets based on mass change, indicating that the fully wetted premix materials are much less abrasive than the un-wetted or partially wetted premix. Additionally, inspection of the wear surface of the paddles at higher magnification showed the flat paddles were worn much more than the helical and is consistent with the wear rates. Aligning the auger discharge flight with the first set of helical paddles was effective in reducing the wear rate as compared to the flat paddle configuration. Changing the paddle configuration from flat to helical resulted in a slight increase in rheological properties. Although, both tests produced grout-like material that is within the processing rage of the SPF, it should be noted that cement is not included in the premix and water was used rather than salt solution, which does affect the rheology of the fresh grout. The higher rheological properties from the helical wear test are most likely due to the reduced number of shearing paddles in the mixer. In addition, there is variation in the rheological data for each wear test. This is most likely due to the way that the dry feeds enter the mixer from the dry feeder. The

  18. Comparative evaluation of nutritional status of elderly dentulous and completely edentulous patients wearing complete dentures

    Directory of Open Access Journals (Sweden)

    Bhumita R Makwana


    Full Text Available Introduction: The scientific progress has reached a level where nutritional interventions may play a part in the prevention of degenerative conditions of age, improvement of quality of life and impact on health care burden and resources. Moreover a timely intervention can stop weight loss in elderly at risk of malnutrition or undernourished. Evaluation of nutritional status is important for any nutrition or dietary modification. We therefore did a comparative study of evaluation of nutritional status of elderly dentulous and completely edentulous patients wearing complete dentures. Rationale: To evaluate nutritional status in dentulous and edentulous denture wearing elderly patient. To evaluate any relationship between edentulous denture wearer patient and malnutrition. To determine if the recommended dietary allowance is met by elderly dentulous and completely edentulous patients wearing complete dentures. To find out the need of nutritional supplement for edentulous complete denture wearer patients. Objectives: The objectives were to evaluate nutritional status in dentulous and edentulous denture wearing elderly patients and to find out any relationship between edentulous denture wearer patients and malnutrition. We also tried to find out the need of nutritional supplement for edentulous denture wearer patients. Material & Method: A total of 100  healthy Male and Female  patients  between the age of 60  to 80 years attending the OPD of Department of Prosthodontics, Faculty of Dental Sciences, Dharmsinh Desai University, Nadiad, Gujarat were selected and divided into two sample groups dentulous and edentulous. Subjects with no natural teeth who reported wearing complete maxillary and   mandibular dentures for at least 6 months were taken as the edentulous sample and subjects with at least 24 teeth who did not wear dentures were taken as dentulous sample. Mini Nutrition Assesment Tool, 24 Hour Diet Recall & Food Frequency Form were used to

  19. Fish survey, fishing duration and other data from otter trawls and scuba observations from NOAA Ship MILLER FREEMAN and other platforms as part of Outer Continental Shelf Environmental Assessment Program (OCSEAP) from 1977-11-04 to 1979-11-26 (NODC Accession 8100532) (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Fish survey, fishing duration, and other data were collected from otter trawls and scuba diver observations from NOAA Ship MILLER FREEMAN and other platforms from 04...

  20. Impacts on daily performances related to wearing orthodontic appliances


    Bernabe, E; Sheiham, A.; Oliveira, C. M.


    Objective: To assess the prevalence, intensity, and extent of the impacts on daily performances related to wearing different types of orthodontic appliances.Materials and Methods: A total of 1657 students, 15 to 16 years old, were randomly selected from those attending all secondary schools in Bauru, Sao Paulo, Brazil. Only those wearing orthodontic appliances at the time of the survey were included. Face-to-face structured interviews were done to collect information about impacts on quality ...

  1. Experiment on wear behavior of high pressure gas seal faces (United States)

    Xu, Jing; Peng, Xudong; Bai, Shaoxian; Meng, Xiangkai; Li, Jiyun


    Current researches show that mechanical deformation of seal ring face makes fluid film clearance decrease at high pressure side, thus a divergent clearance is formed and face wear occurs more seriously at the high pressure side than that on the low pressure side. However, there is still lack of published experimental works enough to prove the theoretical results. In this paper, a spiral groove dry gas seal at high pressures is experimentally investigated so as to prove the face wear happened at the high pressure side of seal faces due to the face mechanical deformation, and the wear behavior affected by seal ring structure is also studied. The experimental results show that face wear would occur at the high pressure side of seal faces due to the deformation, thus the leakage and face temperature increase, which all satisfies the theoretical predictions. When sealed pressure is not less than 5 MPa, the pressure can provide enough opening force to separate the seal faces. The seal ring sizes have obvious influence on face wear. Face wear, leakage and face temperature of a dry gas seal with the smaller cross sectional area of seal ring are less than that of a dry gas seal with bigger one, and the difference of leakage rate between these two sizes of seal face width is in the range of 24%-25%. Compared with the effect of seal ring sizes, the effect of secondary O-ring seal position on face deformation and face wear is less. The differences between these two types of dry gas seals with different secondary O-ring seal positions are less than 5.9% when the rotational speed varies from 0 to 600 r/min. By linking face wear and sealing performance changes to the shift in mechanical deformation of seal ring, this research presents an important experimental method to study face deformation of a dry gas seal at high pressures.

  2. An Anthropological Perspective: Another Dimension to Modern Dental Wear Concepts


    Kaidonis, John A.; Sarbin Ranjitkar; Dimitra Lekkas; Townsend, Grant C.


    For many years, research on tooth wear by dental academics has been diametrically opposite to that of anthropological research, with each discipline having a different understanding as to the nature of the wear processes. Dental focus revolved around preventive and restorative considerations while the anthropological focus was a biological understanding related to human evolution, diet, environment, form, and function and included all the craniofacial structures. Introducing the anthropologic...

  3. Wear Assessment of Conical Pick used in Coal Cutting Operation (United States)

    Dewangan, Saurabh; Chattopadhyaya, Somnath; Hloch, Sergej


    Conical pick is a widely used tool for cutting coal in mines. It has a cemented carbide tip inserted in a steel body. Cemented carbide has been in use for many years for coal/rock cutting because it has the optimum combination of hardness, toughness and resistance against abrasive wear. As coal/rock is a heterogeneous substance, the cutting tool has to undergo various obstructions at the time of excavation that cause the tool to wear out. The cracks and fractures developing in the cemented carbide limit the life of the tool. For a long time, different wear mechanisms have been studied to develop improved grades of cemented carbide with high wear resistance properties. The research is still continuing. Moreover, due to the highly unpredictable nature of coal/rock, it is not easy to understand the wear mechanisms. In the present work, an attempt has been made to understand the wear mechanisms in four conical picks, which were used in a continuous miner machine for underground mining of coal. The wearing pattern of the conical pick indicates damage in its cemented carbide tip as well as the steel body. The worn out parts of the tools have been critically examined using scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) point analysis. Mainly four types of wear mechanisms, namely, coal/rock intermixing, plastic deformation, rock channel formation and crushing and cracking, have been detected. The presence of coal/rock material and their respective concentrations in the selected area of worn out surface were observed using the spectra generated by EDX analysis.

  4. Influence of Heat Treatment on Abrasive Wear Resistance of Silumin Matrix Composite Castings

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    Gawdzińska K.


    Full Text Available The authors attempted at examining the effect of heat treatment on abrasive wear resistance of metal composite castings. Metal matrix composites were made by infiltrating preforms created from unordered short fibers (graphite or silumin with liquid aluminium alloy AlSi12(b. Thus prepared composites were subject to solution heat treatment at a temperature of 520°C for four hours, then aging at a temperature of 220°C for four hours. Abrasion resistance of the material was tested before and after thermal treatment.

  5. Impact Wear of Structural Steel with Yield Strength of 235 MPa in Various Liquids

    NARCIS (Netherlands)

    Liu, Y.; Janssen, G.C.A.M.


    The wear of pipelines, used in slurry transport, results in high costs for maintenance and replacement. The wear mechanism involves abrasion, corrosion, impact, and the interaction among them. In this work, we study the effect of impact on the wear mechanism and wear rate. Results show that when the

  6. Policies for Probe-Wear Leveling in MEMS-Based Storage Devices

    NARCIS (Netherlands)

    Khatib, M.G.; Hartel, Pieter H.


    Probes (or read/write heads) in MEMS-based storage devices are susceptible to wear. We study probe wear, and analyze the causes of probe uneven wear. We show that under real-world traces some probes can wear one order of magnitude faster than other probes leading to premature expiry of some probes.

  7. Detecting Safety Zone Drill Process Parameters for Uncoated HSS Twist Drill in Machining GFRP Composites by Integrating Wear Rate and Wear Transition Mapping

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    Sathish Rao Udupi


    Full Text Available The previous research investigations informed that the tool wear of any machining operation could be minimized by controlling the machining factors such as speed, feed, geometry, and type of cutting tool. Hence the present research paper aims at controlling the process parameters to minimize the drill tool wear, during the machining of Glass Fiber Reinforced Polymer (GFRP composites. Experiments were carried out to find the tool wear rate and a wear mechanism map of uncoated High Speed Steel (HSS drill of 10 mm diameter was developed for the drilling of GFRP composite laminates. The surface micrograph images on the drill land surface displayed dominant wear mechanisms induced on HSS drill during machining of GFRP and they were found to be adhesive wear, adhesive and abrasive wear, abrasive wear, and diffusion and fatigue wear. A “safety wear zone” was identified on the wear mechanism map, where the minimum tool wear of the HSS drill occurs. From the safety zone boundaries, it was inferred that the drill spindle speed should be set between 1200 and 1590 rpm and feed rate must be set within a range of 0.10–0.16 mm/rev for GFRP work and HSS tool combination to enhance the service life of 10 mm HSS drills and to minimize the tool wear.

  8. Dendritic Arm Spacing Affecting Mechanical Properties and Wear Behavior of Al-Sn and Al-Si Alloys Directionally Solidified under Unsteady-State Conditions (United States)

    Cruz, Kleber S.; Meza, Elisangela S.; Fernandes, Frederico A. P.; Quaresma, José M. V.; Casteletti, Luiz C.; Garcia, Amauri


    Alloys of Al-Sn and Al-Si are widely used in tribological applications such as cylinder liners and journal bearings. Studies of the influence of the as-cast microstructures of these alloys on the final mechanical properties and wear resistance can be very useful for planning solidification conditions in order to permit a desired level of final properties to be achieved. The aim of the present study was to contribute to a better understanding about the relationship between the scale of the dendritic network and the corresponding mechanical properties and wear behavior. The Al-Sn (15 and 20 wt pct Sn) and Al-Si (3 and 5 wt pct Si) alloys were directionally solidified under unsteady-state heat flow conditions in water-cooled molds in order to permit samples with a wide range of dendritic spacings to be obtained. These samples were subjected to tensile and wear tests, and experimental quantitative expressions correlating the ultimate tensile strength (UTS), yield tensile strength, elongation, and wear volume to the primary dendritic arm spacing (DAS) have been determined. The wear resistance was shown to be significantly affected by the scale of primary dendrite arm spacing. For Al-Si alloys, the refinement of the dendritic array improved the wear resistance, while for the Al-Sn alloys, an opposite effect was observed, i.e., the increase in primary dendrite arm spacing improved the wear resistance. The effect of inverse segregation, which is observed for Al-Sn alloys, on the wear resistance is also discussed.

  9. Standard guide for measuring the wear volumes of piston ring segments run against flat coupons in reciprocating wear tests

    CERN Document Server

    American Society for Testing and Materials. Philadelphia


    1.1 This guide covers and describes a profiling method for use accurately measuring the wear loss of compound-curved (crowned) piston ring specimens that run against flat counterfaces. It does not assume that the wear scars are ideally flat, as do some alternative measurement methods. Laboratory-scale wear tests have been used to evaluate the wear of materials, coatings, and surface treatments that are candidates for piston rings and cylinder liners in diesel engines or spark ignition engines. Various loads, temperatures, speeds, lubricants, and durations are used for such tests, but some of them use a curved piston ring segment as one sliding partner and a flat or curved specimen (simulating the cylinder liner) as its counterface. The goal of this guide is to provide more accurate wear measurements than alternative approaches involving weight loss or simply measuring the length and width of the wear marks. 1.2 This standard does not purport to address all of the safety concerns, if any, associated with its ...

  10. Wear analysis of disc cutters of full face rock tunnel boring machine (United States)

    Zhang, Zhaohuang; Meng, Liang; Sun, Fei


    Wear is a major factor of disc cutters' failure. No current theory offers a standard for the prediction of disc cutter wear yet. In the field the wear prediction method commonly used is based on the excavation length of tunnel boring machine(TBM) to predict the disc cutter wear and its wear law, considering the location number of each disc cutter on the cutterhead(radius for installation); in theory, there is a prediction method of using arc wear coefficient. However, the preceding two methods have their own errors, with their accuracy being 40% or so and largely relying on the technicians' experience. Therefore, radial wear coefficient, axial wear coefficient and trajectory wear coefficient are defined on the basis of the operating characteristics of TBM. With reference to the installation and characteristics of disc cutters, those coefficients are modified according to penetration, which gives rise to the presentation of comprehensive axial wear coefficient, comprehensive radial wear coefficient and comprehensive trajectory wear coefficient. Calculation and determination of wear coefficients are made with consideration of data from a segment of TBM project(excavation length 173 m). The resulting wear coefficient values, after modification, are adopted to predict the disc cutter wear in the follow-up segment of the TBM project(excavation length of 5621 m). The prediction results show that the disc cutter wear predicted with comprehensive radial wear coefficient and comprehensive trajectory wear coefficient are not only accurate(accuracy 16.12%) but also highly congruous, whereas there is a larger deviation in the prediction with comprehensive axial wear coefficient(accuracy 41%, which is in agreement with the prediction of disc cutters' life in the field). This paper puts forth a new method concerning prediction of life span and wear of TBM disc cutters as well as timing for replacing disc cutters.

  11. WearSense: Detecting Autism Stereotypic Behaviors through Smartwatches

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    Amir Mohammad Amiri


    Full Text Available Autism is a complex developmental disorder that affects approximately 1 in 68 children (according to the recent survey conducted by the Centers for Disease Control and Prevention—CDC in the U.S., and has become the fastest growing category of special education. Each student with autism comes with her or his own unique needs and an array of behaviors and habits that can be severe and which interfere with everyday tasks. Autism is associated with intellectual disability, impairments in social skills, and physical health issues such as sleep and abdominal disturbances. We have designed an Internet-of-Things (IoT framework named WearSense that leverages the sensing capabilities of modern smartwatches to detect stereotypic behaviors in children with autism. In this work, we present a study that used the inbuilt accelerometer of a smartwatch to detect three behaviors, including hand flapping, painting, and sibbing that are commonly observed in children with autism. In this feasibility study, we recruited 14 subjects to record the accelerometer data from the smartwatch worn on the wrist. The processing part extracts 34 different features in each dimension of the three-axis accelerometer, resulting in 102 features. Using and comparing various classification techniques revealed that an ensemble of 40 decision trees has the best accuracy of around 94.6%. This accuracy shows the quality of the data collected from the smartwatch and feature extraction methods used in this study. The recognition of these behaviors by using a smartwatch would be helpful in monitoring individuals with autistic behaviors, since the smartwatch can send the data to the cloud for comprehensive analysis and also to help parents, caregivers, and clinicians make informed decisions.

  12. Comparing subjective and objective measures of headgear compliance. (United States)

    Bos, Annemieke; Kleverlaan, Cornelis J; Hoogstraten, Johan; Prahl-Andersen, Birte; Kuitert, Rein


    Many studies have used subjective measures to examine patient compliance during orthodontic treatment. Objective measurement of compliance has been confined to only a few studies that used electronic timing devices built into removable appliances. Our aim in this study was to compare subjective and objective methods of measuring compliance with headgear wear. It was hypothesized that orthodontists, patients, and patients' parents overestimate compliance and report more wearing hours than the headgear timers indicate. Also, relationships between sex, age, treatment time, and headgear compliance were explored. A headgear timer device and 3 questionnaires were developed to assess compliance. The subjects were unaware that their headgear use was being measured. Significant differences between the estimates of orthodontists, patients, parents, and headgear timer scores were found. Also, there were differences regarding age and treatment time. Subjective measures might result in overestimation of compliance. This suggests that the use of an objective instrument to measure headgear compliance should be continued in future studies.

  13. Relating factors to wearing personal radiation protectors among healthcare professionals. (United States)

    Heo, Yunjeong; Chun, Hosun; Kang, Seonghoon; Lee, Wonjin; Jang, Taewon; Park, Jongtae


    With increasing use of medical radiologic procedures, wearing proper protector should be emphasized to reduce occupational radiation exposures. This research describes the rates of lead apron wearing for radiation protection and assessed occupational factors related to wearing rates for various types of healthcare professionals. We conducted a self-administered questionnaire survey through a website, on-site visits, fax, and mail. Of the 13,489 participants, 8858 workers who could not completely separate themselves from radiological procedure areas. Their general characteristics (sex and age), work history (job title, duration of employment, and hospital type), and practices (frequency of radiation procedures, ability to completely separate from radiation, and frequency of wearing protective lead aprons) were examined. The mean rate of lead apron wearing during radiologic procedures was 48.0 %. The rate was different according to sex (male: 52.9 %, female: 39.6 %), hospital type (general hospital: 63.0 %, hospital: 51.3 %, clinic: 35.6 %, dental hospital/clinic: 13.3 %, public health center: 22.8 %), and job title (radiologic technologist: 50.3 %, doctor: 70.3 %, dentist/dental hygienist: 15.0 %, nurse/nursing assistant: 64.5 %) (p lead aprons by radiologic technologists and nurses/nursing assistants was associated with hospital type and exposure frequency score. For doctors, apron wearing was associated with employment duration. For dentists/dental hygienists, apron wearing was associated with the exposure frequency score. To improve working environments for healthcare professionals exposed to radiation, it is necessary to consider related factors, such as job title, duration of employment, and hospital type, when utilizing a planning and management system to prevent radiation-related health problems.

  14. Fissure sealant materials: Wear resistance of flowable composite resins. (United States)

    Asefi, Sohrab; Eskandarion, Solmaz; Hamidiaval, Shadi


    Background. Wear resistance of pit and fissure sealant materials can influence their retention. Wear characteristics of sealant materials may determine scheduling of check-up visits. The aim of this study was to compare wear resistance of two flowable composite resins with that of posterior composite resin materials. Methods. Thirty-five disk-shaped specimens were prepared in 5 groups, including two flowable composite resins (Estelite Flow Quick and Estelite Flow Quick High Flow), Filtek P90 and Filtek P60 and Tetric N-Ceram. The disk-shaped samples were prepared in 25-mm diameter by packing them into a two-piece aluminum mold and then light-cured. All the specimens were polished for 1minute using 600-grit sand paper. The samples were stored in distilled water at room temperature for 1 week and then worn by two-body abrasion test using "pin-on-disk" method (with distilled water under a 15-Nload at 0.05 m/s, for a distance of 100 meter with Steatite ceramic balls antagonists). A Profilometer was used for evaluating the surface wear. Data were analyzed with the one-way ANOVA. Results. Estelite Flow Quick exhibited 2708.9 ± 578.1 μm(2) and Estelite Flow Quick High Flow exhibited 3206 ± 2445.1 μm(2)of wear but there were no significant differences between the groups. They demonstrated similar wear properties. Conclusion. Estelite flowable composite resins have wear resistance similar to nano- and micro-filled and micro-hybrid composite resins. Therefore, they can be recommended as pit and fissure sealant materials in the posterior region with appropriate mechanical characteristics.

  15. Impact of Advertising on Tampon Wear-time Practices

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    Kara E. Woeller


    Full Text Available Objectives (1 To determine whether advertising nighttime tampon use for up to eight hours was understood to be consistent with label recommendations and (2 to determine whether television and print advertising with this message affected tampon wear times in adults and teens. Methods (1 A comprehension study (online advertising and follow-up questionnaire among women aged 14–49 years (300 per group who viewed either the test or a control advertising message; (2 Diary-based surveys of tampon wear times performed prior to ( n = 292 adults, 18–49 years, 74 teens, 12–17 years and after ( n = 287 adults, 104 teens the launch of national advertising. Results Significantly more test message viewers than controls stated tampons should be worn less than or equal to eight hours (93.6% vs. 88.6%, respectively, P = 0.049. A directionally higher percentage of test message viewers said they would use a pad if sleeping longer than eight hours (52% vs. 42% of controls. Among the women who used tampons longer than eight hours when sleeping, 52% reported they would wake up and change compared with 45% of controls. No significant difference between baseline and follow-up diary surveys was found among teens or adults in various measures of tampon wear time (mean wear times; usage intervals from less than two hours to more than 10 hours; percentage of tampons used for more than or equal to eight hours; frequency of wearing at least one tampon more than eight hours. Conclusions Advertising nighttime tampon wear for up to eight hours effectively communicated label recommendations but did not alter tampon wear times. The informational intervention had limited impact on established habits.

  16. Fissure sealant materials: Wear resistance of flowable composite resins

    Directory of Open Access Journals (Sweden)

    Sohrab Asefi


    Full Text Available Background. Wear resistance of pit and fissure sealant materials can influence their retention. Wear characteristics of sealant materials may determine scheduling of check-up visits. The aim of this study was to compare wear resistance of two flowable composite resins with that of posterior composite resin materials. Methods. Thirty-five disk-shaped specimens were prepared in 5 groups, including two flowable composite resins (Estelite Flow Quick and Estelite Flow Quick High Flow, Filtek P90 and Filtek P60 and Tetric N-Ceram. The disk-shaped samples were prepared in 25-mm diameter by packing them into a two-piece aluminum mold and then light-cured. All the specimens were polished for 1minute using 600-grit sand paper. The samples were stored in distilled water at room temperature for 1 week and then worn by two-body abrasion test using "pin-on-disk" method (with distilled water under a 15-Nload at 0.05 m/s, for a distance of 100 meter with Steatite ceramic balls antagonists. A Profilometer was used for evaluating the surface wear. Data were analyzed with the one-way ANOVA. Results. Estelite Flow Quick exhibited 2708.9 ± 578.1 μm2 and Estelite Flow Quick High Flow exhibited 3206 ± 2445.1 μm2of wear but there were no significant differences between the groups. They demonstrated similar wear properties. Conclusion. Estelite flowable composite resins have wear resistance similar to nano- and micro-filled and micro-hybrid composite resins. Therefore, they can be recommended as pit and fissure sealant materials in the posterior region with appropriate mechanical characteristics.

  17. Corneal changes after suspending contact lens wear in early pellucid marginal corneal degeneration and moderate keratoconus. (United States)

    Jinabhai, Amit; Radhakrishnan, Hema; O'Donnell, Clare


    This case study reports on how refraction, visual acuity, and ocular higher-order aberrations changed after rigid gas-permeable (RGP) lens wear was suspended by a patient with early pellucid marginal corneal degeneration (PMD) and by a patient with moderate keratoconus. Alterations in central corneal power and axes, central corneal thickness, and corneal topography were also explored. Ocular aberrations and Scheimpflug photography were measured at 2 visits, 7 days apart, after the patients had removed their contact lenses. Subjective refraction and logarithm of the minimum angle of resolution visual acuities were also recorded at both visits. In contrast to the keratoconic patient, the patient with early PMD showed changes in subjective refraction (approximately -1.75 diopter cylinder of astigmatism), front surface central powers (∼1.3 diopter [D] horizontally and 2 D vertically), and anterior surface topography (∼1.2 D) between visits. Both patients showed an increase in total higher-order root mean square (HORMS) aberrations after suspending lens wear (∼0.40 μm for the moderately keratoconic patient and 0.22 μm for the early PMD patient). Changes in the optical and structural parameters of the cornea after suspending lens wear are likely to be dependent on a multitude of factors, such as the lens fitting and the biomechanical properties of the cornea. The findings of this report may be useful to practitioners when refracting or refitting existing RGP lens wearers with ectasia or to those involved in prescribing aberration-controlling contact lenses for conditions such as keratoconus and PMD.

  18. How experienced alpine-skiers cope with restrictions of ankle degrees-of-freedom when wearing ski-boots in postural exercises. (United States)

    Noé, Frédéric; Amarantini, David; Paillard, Thierry


    The present study investigates the mechanisms underlying changes in postural strategy that occur to compensate for mechanical ankle joint restrictions induced by wearing ski-boots during postural exercises. Fourteen experienced skiers were asked to stand as still as possible in a stable (STA) posture and in 2 postures with instability in the medio/lateral and antero/posterior (ML and AP postures) direction. Postural tasks were performed with eyes open or closed and while wearing or not wearing ski-boots. The electromyographic (EMG) activity of representative lower limb muscles and positions of centre-of-foot pressure (COP) were recorded and analyzed. Our results illustrated enhanced postural performances with ski-boots in the STA posture, whereas postural performances remained unchanged when wearing ski-boots in the ML and AP postures. Analysis of COP sways in the frequency domain did not illustrate any modification in the contribution of different neuronal loops when the study subjects wore ski-boots. EMG showed that the mechanical effects of wearing ski-boots were compensated by changes in postural strategy through the reorganization of muscle coordination, made possible by inherent redundancies in the human body. The preservation of postural performances, despite restrictions of ankle degrees-of-freedom induced by ski-boots, emphasizes the subjects' capacity to exploit the additional support provided by ski-boots by adequately adjusting muscle coordination to control posture in different balance conditions.

  19. Risk factors for moderate and severe microbial keratitis in daily wear contact lens users. (United States)

    Stapleton, Fiona; Edwards, Katie; Keay, Lisa; Naduvilath, Thomas; Dart, John K G; Brian, Garry; Holden, Brien


    To establish risk factors for moderate and severe microbial keratitis among daily contact lens (CL) wearers in Australia. A prospective, 12-month, population-based, case-control study. New cases of moderate and severe microbial keratitis in daily wear CL users presenting in Australia over a 12-month period were identified through surveillance of all ophthalmic practitioners. Case detection was augmented by record audits at major ophthalmic centers. Controls were users of daily wear CLs in the community identified using a national telephone survey. Cases and controls were interviewed by telephone to determine subject demographics and CL wear history. Multiple binary logistic regression was used to determine independent risk factors and univariate population attributable risk percentage (PAR%) was estimated for each risk factor. Independent risk factors, relative risk (with 95% confidence intervals [CIs]), and PAR%. There were 90 eligible moderate and severe cases related to daily wear of CLs reported during the study period. We identified 1090 community controls using daily wear CLs. Independent risk factors for moderate and severe keratitis while adjusting for age, gender, and lens material type included poor storage case hygiene 6.4× (95% CI, 1.9-21.8; PAR, 49%), infrequent storage case replacement 5.4× (95% CI, 1.5-18.9; PAR, 27%), solution type 7.2× (95% CI, 2.3-22.5; PAR, 35%), occasional overnight lens use (<1 night per week) 6.5× (95% CI, 1.3-31.7; PAR, 23%), high socioeconomic status 4.1× (95% CI, 1.2-14.4; PAR, 31%), and smoking 3.7× (95% CI, 1.1-12.8; PAR, 31%). Moderate and severe microbial keratitis associated with daily use of CLs was independently associated with factors likely to cause contamination of CL storage cases (frequency of storage case replacement, hygiene, and solution type). Other factors included occasional overnight use of CLs, smoking, and socioeconomic class. Disease load may be considerably reduced by attention to modifiable

  20. Study on Composition, Microstructure and Wear Behavior of Fe-B-C Wear-Resistant Surfacing Alloys (United States)

    Zhuang, Minghui; Li, Muqin; Wang, Jun; Ma, Zhen; Yuan, Shidan


    Fe-B-C alloy layers with various microstructures were welded on Q235 steel plates using welding powders/H08Mn2Si and welding wires composite surfacing technology. The relationship existing between the chemical composition, microstructure and wear resistance of the surfacing alloy layers was investigated by scanning electron microscopy, x-ray diffraction, electron backscatter diffraction and wear tests. The results demonstrated that the volume fractions and morphologies of the microstructures in the surfacing alloy layers could be controlled by adjusting the boron and carbon contents in the welding powders, which could further regulate the wear resistance of the surfacing alloy layers. The typical microstructures of the Fe-B-C surfacing alloy layers included dendritic Fe, rod-like Fe2B, fishbone-like Fe2B and daisy-like Fe3(C, B). The wear resistance of the alloy layers with various morphologies differed. The wear resistance order of the different microstructures was: rod-like Fe2B > fishbone-like Fe2B > daisy-like Fe3(C, B) > dendritic Fe. A large number of rod-like Fe2B with high microhardness could be obtained at the boron content of 5.70 5.90 wt.% and the carbon content of 0.50 0.60wt.%. The highest wear resistance of the Fe-B-C alloy layers reached the value of 24.1 g-1, which demonstrates the main microscopic cutting wear mechanism of the Fe-B-C alloy layers.