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Sample records for ablative fractional resurfacing

  1. Laser systems for ablative fractional resurfacing.

    PubMed

    Paasch, Uwe; Haedersdal, Merete

    2011-01-01

    Ablative fractional resurfacing (AFR) creates microscopic vertical ablated channels that are surrounded by a thin layer of coagulated tissue, constituting the microscopic treatment zones (MTZs). AFR induces epidermal and dermal remodeling, which raises new possibilities for the treatment of a variety of skin conditions, primarily chronically photodamaged skin, but also acne and burn scars. In addition, it is anticipated that AFR can be utilized in the laser-assisted delivery of topical drugs. Clinical efficacy coupled with minimal downtime has driven the development of various fractional ablative laser systems. Fractionated CO(2) (10,600-nm), erbium yttrium aluminum garnet, 2940-nm and yttrium scandium gallium garnet, 2790-nm lasers are available. In this article, we present an overview of AFR technology, devices and histopathology, and we summarize the current clinical possibilities with AFR incorporating our personal experience. AFR is still in the exploratory era, and systematic investigations of clinical outcomes related to various system settings are needed. PMID:21158542

  2. Ablative Fractional Laser Resurfacing: A Promising Adjunct to Surgical Reconstruction.

    PubMed

    Griffin, David; Brelsford, Megan; O'Reilly, Eamon; Stroup, Sean P; Shumaker, Peter

    2016-06-01

    Ablative fractional laser resurfacing (AFLR) is emerging as a safe and effective treatment option for the mitigation of cosmetic and functional deficits resulting from traumatic scars and scar contractures. Military centers of excellence engaged in the multidisciplinary rehabilitation of wounded warriors have been instrumental in the widening acceptance of the technique in both the military and civilian realms. Despite the end of large-scale combat operations, AFLR remains a promising complement to surgical reconstruction and a novel option in challenging clinical situations that defy resolution with traditional methods. Herein, we present the case of a man in his 50s who underwent extensive genital and perineal debridement related to Fournier's gangrene. Despite successful reconstruction including extensive skin grafting, the patient suffered from intractable discomfort related to developing scar contractures that responded rapidly to a course of AFLR. This case serves to highlight the potential benefits of AFLR for postoperative wound management, and the importance of a multidisciplinary approach for the care of complex injuries. PMID:27244076

  3. Ablative skin resurfacing.

    PubMed

    Agrawal, Nidhi; Smith, Greg; Heffelfinger, Ryan

    2014-02-01

    Ablative laser resurfacing has evolved as a safe and effective treatment for skin rejuvenation. Although traditional lasers were associated with significant thermal damage and lengthy recovery, advances in laser technology have improved safety profiles and reduced social downtime. CO2 lasers remain the gold standard of treatment, and fractional ablative devices capable of achieving remarkable clinical improvement with fewer side effects and shorter recovery times have made it a more practical option for patients. Although ablative resurfacing has become safer, careful patient selection and choice of suitable laser parameters are essential to minimize complications and optimize outcomes. This article describes the current modalities used in ablative laser skin resurfacing and examines their efficacy, indications, and possible side effects. PMID:24488638

  4. Laser Resurfacing: Full Field and Fractional.

    PubMed

    Pozner, Jason N; DiBernardo, Barry E

    2016-07-01

    Laser resurfacing is a very popular procedure worldwide. Full field and fractional lasers are used in many aesthetic practices. There have been significant advances in laser resurfacing in the past few years, which make patient treatments more efficacious and with less downtime. Erbium and carbon dioxide and ablative, nonablative, and hybrid fractional lasers are all extremely effective and popular tools that have a place in plastic surgery and dermatology offices. PMID:27363765

  5. Topical corticosteroids minimise the risk of postinflammatory hyper-pigmentation after ablative fractional CO2 laser resurfacing in Asians.

    PubMed

    Cheyasak, Nutjira; Manuskiatti, Woraphong; Maneeprasopchoke, Pitchaya; Wanitphakdeedecha, Rungsima

    2015-02-01

    Postinflammatory hyperpigmentation (PIH) is the most common adverse effect of laser treatment in dark-skinned individuals. Little is known whether PIH can be prevented or minimised. The objective of this study was to investigate the effect of short-term application of topical corticosteroids on the incidence of PIH after ablative fractional resurfacing in Asians. Forty subjects with skin phototype IV and atrophic acne scars were treated with a fractional CO2 laser on both sides of the face. Post-operatively, clobetasol propionate 0.05% ointment was applied to one randomly selected side of the face for the first 2 days, followed by an application of petrolatum jelly for the rest of the week (petrolatum was applied to the other side for 7 days). Assessments on the clinical outcome, the wound healing process and the occurrence of PIH were obtained once weekly for the first month and at 2 and 3 months post-treatment. The side of the face treated with petrolatum alone had significantly (p < 0.001) higher incidence of PIH (75%) after laser irradiation than the side of the face treated with topical corticosteroids and petrolatum (40%). The PIH occurring on the petrolatum-treated sides had significantly higher intensity (p < 0.001) and was spread over a significantly larger area (p < 0.001), compared with the corticosteroid- and petrolatum-treated sides. In conclusion, a short-term application of topical corticosteroids postoperatively is associated with a decreased risk of PIH after ablative fractional resurfacing. PMID:24854088

  6. Case report: rapidly healing epidermolysis bullosa wound after ablative fractional resurfacing.

    PubMed

    Krakowski, Andrew C; Ghasri, Pedram

    2015-01-01

    Recessive dystrophic epidermolysis bullosa (RDEB) is a devastating genodermatosis characterized by generalized skin fragility, severe blistering, and wounding that heals with mutilating scarring. Patients are in constant need of effective wound therapies as they often succumb to aggressive metastatic squamous cell carcinomas or to sepsis that may develop from their chronic wounds. Herein, we demonstrate accelerated wound healing with use of a fractionated CO2 laser protocol in a 22-year-old man with RDEB. His 9-month-old, non-healing wound decreased from 7 cm in diameter to 2 cm in diameter (a 92% reduction in wound surface area) within 4 weeks of a single laser treatment, and he had near-complete re-epithelialization within 4 weeks of his second laser treatment without blistering or other adverse effects. This novel intervention of using fractionated CO2 for photo-microdebridement could help revolutionize wound care for patients who have RDEB and whose chronic wounds serve as one of their greatest sources of morbidity and mortality. Dissemination to a pediatric audience is critical so that laser protocols might be more thoroughly investigated and incorporated into wound management strategies for this uniquely vulnerable population. PMID:25535263

  7. Current Status of Fractional Laser Resurfacing.

    PubMed

    Carniol, Paul J; Hamilton, Mark M; Carniol, Eric T

    2015-01-01

    Fractional lasers were first developed based on observations of lasers designed for hair transplantation. In 2007, ablative fractional laser resurfacing was introduced. The fractionation allowed deeper tissue penetration, leading to greater tissue contraction, collagen production and tissue remodeling. Since then, fractional erbium:YAG resurfacing lasers have also been introduced. These lasers have yielded excellent results in treating photoaging, acne scarring, and dyschromia. With the adjustment of microspot density, pulse duration, number of passes, and fluence, the surgeon can adjust the treatment effects. These lasers have allowed surgeons to treat patients with higher Fitzpatrick skin types (types IV to VI) and greater individualize treatments to various facial subunits. Immunohistochemical analysis has demonstrated remodeling effects of the tissues for several months, producing longer lasting results. Adjuvant treatments are also under investigation, including concomitant face-lift, product deposition, and platelet-rich plasma. Finally, there is a short recovery time from treatment with these lasers, allowing patients to resume regular activities more quickly. Although there is a relatively high safety profile for ablative fractionated lasers, surgeons should be aware of the limitations of specific treatments and the associated risks and complications. PMID:26133312

  8. Fractional Carbon Dioxide Laser Resurfacing

    PubMed Central

    Ramsdell, William M.

    2012-01-01

    Currently available ablative fractional CO2 lasers provide excellent results and diminish down time with fewer complications than previous generation CO2 lasers. Mechanisms of action, treatment parameters, as well as pre- and postoperative care will be discussed. PMID:23904820

  9. 3D in vivo optical skin imaging for intense pulsed light and fractional ablative resurfacing of photodamaged skin.

    PubMed

    Clementoni, Matteo Tretti; Lavagno, Rosalia; Catenacci, Maximilian; Kantor, Roman; Mariotto, Guido; Shvets, Igor

    2011-11-01

    The authors present a 3D in vivo imaging system used to assess the effectiveness of IPL and fractional laser treatments of photodamaged skin. Preoperative and postoperative images of patients treated with these procedures are analyzed and demonstrate the superior ability of this 3D technology to reveal decrease in vascularity and improvement in melanin distribution and calculate the degree of individual deep wrinkles before and after treatment. PMID:22004864

  10. Complete resolution of minocycline pigmentation following a single treatment with non-ablative 1550-nm fractional resurfacing in combination with the 755-nm Q-switched alexandrite laser.

    PubMed

    Vangipuram, Ramya K; DeLozier, Whitney L; Geddes, Elizabeth; Friedman, Paul M

    2016-03-01

    Pigmentation secondary to minocycline ingestion is an uncommon adverse event affecting 3.7-14.8% of treated individuals for which few effective therapies are available. Three patterns of minocycline pigmentation have a characteristic clinical and histological appearance. The pigment composition in each variety is different and occurs at varying skin depths. Accordingly, a tailored approach according to the type of minocycline pigmentation is crucial for treatment success. The purpose of this intervention was to evaluate the efficacy of non-ablative fractional photothermolysis in combination with the Q-switched alexandrite laser for the treatment of type I minocycline pigmentation on the face. A patient with type I minocycline pigmentation was treated with non-ablative 1550-nm fractional photothermolysis followed immediately by 755-nm Q-switched alexandrite laser and then observed clinically to determine the outcome of this modality. The patient was seen in clinic 1 month later following her single treatment session and 100% clearance of all blue facial pigment was observed. Non-ablative fractional photothermolysis in combination with the 755-nm Q-switched alexandrite laser should be considered for treatment of type I minocycline pigmentation. PMID:26718463

  11. Nontuberculous Mycobacterial Infection after Fractionated CO2 Laser Resurfacing

    PubMed Central

    Culton, Donna A.; Miller, Becky A.; Miller, Melissa B.; MacKuen, Courteney; Groben, Pamela; White, Becky; Cox, Gary M.; Stout, Jason E.

    2013-01-01

    Nontuberculous mycobacteria are increasingly associated with cutaneous infections after cosmetic procedures. Fractionated CO2 resurfacing, a widely used technique for photorejuvenation, has been associated with a more favorable side effect profile than alternative procedures. We describe 2 cases of nontuberculous mycobacterial infection after treatment with a fractionated CO2 laser at a private clinic. Densely distributed erythematous papules and pustules developed within the treated area within 2 weeks of the laser procedure. Diagnosis was confirmed by histologic analysis and culture. Both infections responded to a 4-month course of a multidrug regimen. An environmental investigation of the clinic was performed, but no source of infection was found. The case isolates differed from each other and from isolates obtained from the clinic, suggesting that the infection was acquired by postprocedure exposure. Papules and pustules after fractionated CO2 resurfacing should raise the suspicion of nontuberculous mycobacterial infection. PMID:23628077

  12. Fractional CO2 Laser Resurfacing as Monotherapy in the Treatment of Atrophic Facial Acne Scars

    PubMed Central

    Majid, Imran; Imran, Saher

    2014-01-01

    Background: While laser resurfacing remains the most effective treatment option for atrophic acne scars, the high incidence of post-treatment adverse effects limits its use. Fractional laser photothermolysis attempts to overcome these limitations of laser resurfacing by creating microscopic zones of injury to the dermis with skip areas in between. Aim: The aim of the present study is to assess the efficacy and safety of fractional CO2 laser resurfacing in atrophic facial acne scars. Materials and Methods: Sixty patients with moderate to severe atrophic facial acne scars were treated with 3-4 sessions of fractional CO2 laser resurfacing at 6-week intervals. The therapeutic response to treatment was assessed at each follow up visit and then finally 6 months after the last laser session using a quartile grading scale. Response to treatment was labelled as ‘excellent’ if there was >50% improvement in scar appearance and texture of skin on the grading scale while 25-50% response and <25% improvement were labelled as ‘good’ and ‘poor’ response, respectively. The overall satisfaction of the patients and any adverse reactions to the treatment were also noted. Results: Most of the patients showed a combination of different morphological types of acne scars. At the time of final assessment 6 months after the last laser session, an excellent response was observed in 26 patients (43.3%) while 15 (25%) and 19 patients (31.7%) demonstrated a good and poor response respectively. Rolling and superficial boxcar scars responded the best while pitted scars responded the least to fractional laser monotherapy. The commonest reported adverse effect was transient erythema and crusting lasting for an average of 3-4 and 4-6 days, respectively while three patients developed post-inflammatory pigmentation lasting for 8-12 weeks. Conclusions: Fractional laser resurfacing as monotherapy is effective in treating acne scars especially rolling and superficial boxcar scars with minimal

  13. Efficiency of Carbon Dioxide Fractional Laser in Skin Resurfacing

    PubMed Central

    Petrov, Andrej

    2016-01-01

    AIM: The aim of the study was to confirm the efficiency and safety of the fractional CO2 laser in skin renewal and to check the possibility of having a synergistic effect in patients who besides carbon dioxide laser are treated with PRP (platelet-rich plasma) too. MATERIAL AND METHODS: The first group (Examined Group 1 or EG1) included 107 patients treated with fractional CO2 laser (Lutronic eCO2) as mono-therapy. The second group (Control Group or CG) covered 100 patients treated with neither laser nor plasma in the same period but subjected to local therapy with drugs or other physio-procedures under the existing protocols for treatment of certain diseases. The third group (Examined Group 2 or EG2) treated 25 patients with combined therapy of CO2 laser and PRP in the treatment of facial rejuvenation or treatment of acne scars. RESULTS: Patient’s satisfaction, in general, is significantly greater in both examined groups (EG1 and EG2) (p < 0.001). It was found the significant difference between control and examined group from the treatment in acne scar (Fisher exact two tailed p < 0.001). Patients satisfaction with the treatment effect in rejuvenation of the skin is significant (χ2 = 39.41; df = 4; p < 0.001). But, patients satisfaction from the treatment with HPV on the skin was significantly lower in examined group (treated with laser), p = 0.0002. CONCLUSION: Multifunctional fractional carbon dioxide laser used in treatment of patients with acne and pigmentation from acne, as well as in the treatment of scars from different backgrounds, is an effective and safe method that causes statistically significant better effect of the treatment, greater patients’ satisfaction, minimal side effects and statistically better response to the therapy, according to assessments by the patient and the therapist. PMID:27335599

  14. YSGG 2790-nm superficial ablative and fractional ablative laser treatment.

    PubMed

    Smith, Kevin C; Schachter, G Daniel

    2011-05-01

    The 2790-nm wavelength YSGG laser was introduced for aesthetic purposes under the trade name Pearl by Cutera in 2007. In clinical use, the Pearl superficial resurfacing laser has proved effective and well tolerated for the correction of superficial brown epidermal dyschromia and superficial fine lines and scars, and the Pearl Fractional laser produces excellent improvement in both dyschromia and improvement of deeper lines and moderately deep acne scarring. The two laser treatments can be combined in a single treatment session on different parts of the face or on the entire face, depending on patient needs and priorities. PMID:21763987

  15. A split-face comparison of ablative fractional lasers (CO(2) and Er:YAG) in Asian patients; postprocedure erythema, pain and patient's satisfaction.

    PubMed

    Jung, Kyung Eun; Jung, Kum Hee; Park, Young Min; Lee, Jun Young; Kim, Tae Yoon; Kim, Hyung Ok; Kim, Hei Sung

    2013-04-01

    Fractional photothermolysis has become popular in the recent years and is currently widely used for the treatment of scars and for photo-rejuvenation purposes. The fractional photothermolysis is to thermally alter a 'fraction' of the skin, leaving intervening areas of normal skin untouched, which rapidly repopulate the altered columns of tissue. Fractional photothermolysis is subdivided into non-ablative and ablative fractional resurfacing. Ablative fractional resurfacing uses fractional CO(2) or Er:YAG lasers to create deeper columns of thermal damage.Few studies have compared fractional CO(2) and Er:YAG lasers on scars and cutaneous photodamages by a split trial. In this pilot study, we have compared the effects, down time, postprocedure erythema, pain of CO(2) and Er:YAG fractional lasers using analysis of clinical photographs, dermoscopic findings and patient's rate of satisfaction. PMID:23464882

  16. Feasibility of ablative fractional laser-assisted drug delivery with optical coherence tomography.

    PubMed

    Yang, Chih-Hsun; Tsai, Meng-Tsan; Shen, Su-Chin; Ng, Chau Yee; Jung, Shih-Ming

    2014-11-01

    Fractional resurfacing creates hundreds of microscopic wounds in the skin without injuring surrounding tissue. This technique allows rapid wound healing owing to small injury regions, and has been proven as an effective method for repairing photodamaged skin. Recently, ablative fractional laser (AFL) treatment has been demonstrated to facilitate topical drug delivery into skin. However, induced fractional photothermolysis depends on several parameters, such as incident angle, exposure energy, and spot size of the fractional laser. In this study, we used fractional CO2 laser to induce microscopic ablation array on the nail for facilitating drug delivery through the nail. To ensure proper energy delivery without damaging tissue structures beneath the nail plate, optical coherence tomography (OCT) was implemented for quantitative evaluation of induced microscopic ablation zone (MAZ). Moreover, to further study the feasibility of drug delivery, normal saline was dripped on the exposure area of fingernail and the speckle variance in OCT signal was used to observe water diffusion through the ablative channels into the nail plate. In conclusion, this study establishes OCT as an effective tool for the investigation of fractional photothermolysis and water/drug delivery through microscopic ablation channels after nail fractional laser treatment. PMID:25426321

  17. Feasibility of ablative fractional laser-assisted drug delivery with optical coherence tomography

    PubMed Central

    Yang, Chih-Hsun; Tsai, Meng-Tsan; Shen, Su-Chin; Ng, Chau Yee; Jung, Shih-Ming

    2014-01-01

    Fractional resurfacing creates hundreds of microscopic wounds in the skin without injuring surrounding tissue. This technique allows rapid wound healing owing to small injury regions, and has been proven as an effective method for repairing photodamaged skin. Recently, ablative fractional laser (AFL) treatment has been demonstrated to facilitate topical drug delivery into skin. However, induced fractional photothermolysis depends on several parameters, such as incident angle, exposure energy, and spot size of the fractional laser. In this study, we used fractional CO2 laser to induce microscopic ablation array on the nail for facilitating drug delivery through the nail. To ensure proper energy delivery without damaging tissue structures beneath the nail plate, optical coherence tomography (OCT) was implemented for quantitative evaluation of induced microscopic ablation zone (MAZ). Moreover, to further study the feasibility of drug delivery, normal saline was dripped on the exposure area of fingernail and the speckle variance in OCT signal was used to observe water diffusion through the ablative channels into the nail plate. In conclusion, this study establishes OCT as an effective tool for the investigation of fractional photothermolysis and water/drug delivery through microscopic ablation channels after nail fractional laser treatment. PMID:25426321

  18. Safe and effective one-session fractional skin resurfacing using a carbon dioxide laser device in super-pulse mode: a clinical and histologic study.

    PubMed

    Trelles, Mario A; Shohat, Michael; Urdiales, Fernando

    2011-02-01

    Carbon dioxide (CO(2)) laser ablative fractional resurfacing produces skin damage, with removal of the epidermis and variable portions of the dermis as well as associated residual heating, resulting in new collagen formation and skin tightening. The nonresurfaced epidermis helps tissue to heal rapidly, with short-term postoperative erythema. The results for 40 patients (8 men and 32 women) after a single session of a fractional CO(2) resurfacing mode were studied. The treatments included resurfacing of the full face, periocular upper lip, and residual acne scars. The patients had skin prototypes 2 to 4 and wrinkle degrees 1 to 3. The histologic effects, efficacy, and treatment safety in various clinical conditions and for different phototypes are discussed. The CO(2) laser for fractional treatment is used in super-pulse mode. The beam is split by a lens into several microbeams, and super-pulse repetition is limited by the pulse width. The laser needs a power adaptation to meet the set fluence per microbeam. Laser pulsing can operate repeatedly on the same spot or be moved randomly over the skin, using several passes to achieve a desired residual thermal effect. Low, medium, and high settings are preprogrammed in the device, and they indicate the strength of resurfacing. A single treatment was given with the patient under topical anesthesia. However, the anesthesia was injected on areas of scar tissue. Medium settings (2 Hz, 30 W, 60 mJ) were used, and two passes were made for dark skins and degree 1 wrinkles. High settings (2 Hz, 60 W, 120 mJ) were used, and three passes were made for degree 3 wrinkles and scar tissue. Postoperatively, resurfaced areas were treated with an ointment of gentamycin, Retinol Palmitate, and DL-methionine (Novartis; Farmaceutics, S.A., Barcelona, Spain). Once epithelialization was achieved, antipigment and sun protection agents were recommended. Evaluations were performed 15 days and 2 months after treatment by both patients and

  19. Immunohistochemical evaluation of the heat shock response to nonablative fractional resurfacing

    NASA Astrophysics Data System (ADS)

    Hantash, Basil M.; Bedi, Vikramaditya P.; Struck, Steven K.; Chan, Kin F.

    2010-11-01

    Despite the emergence of nonablative fractional resurfacing (NFR) as a new therapeutic modality for skin photoaging, little is known about the molecular events that underlie the heat shock response to different treatment parameters. Human subjects are treated with a scanned 1550-nm fractional laser at pulse energies spanning 6 to 40 mJ and a 140-μm spot size. The heat shock response is assessed immunohistochemically immediately through 7 days posttreatment. At the immediately posttreatment time point, we observe subepidermal clefting in most sections. The basal epidermis and dermal zones of sparing are both found to express HSP47, but not HSP72. By day 1, expression of HSP72 is detected throughout the epidermis, while that of HSP47 remains restricted to the basal layer. Both proteins are detected surrounding the dermal portion of the microscopic treatment zone (MTZ). This pattern of expression persists through day 7 post-NFR, although neither protein is found within the MTZ. Immediately posttreatment, the mean collagen denaturation zone width is 50 μm at 6 mJ, increasing to 202 μm at 40 mJ. The zone of cell death exceeds the denaturation zone by 19 to 55% over this pulse energy range. The two zones converge by day 7 posttreatment.

  20. Bacterial infections following non-ablative fractional laser treatment: a case series and discussion.

    PubMed

    Xu, Lisa Y; Kilmer, Suzanne L; Ross, E Victor; Avram, Mathew M

    2015-02-01

    Non-ablative fractional laser procedures have become increasingly popular since their introduction in 2004. The fractional 1,927 nm thulium laser is a non-ablative device that penetrates up to 300 μm in the skin and the 1,550 nm erbium:glass laser penetrates up to 1,400 μm. These procedures are considered minimally invasive with a high safety profile; therefore, infectious complications are exceedingly rare. However, we report five recent cases of bacterial infection with both gram-positive and gram-negative organisms following treatment with the fractional 1550/1927 nm laser approximately 1 day to 1 week post-procedure. One patient had a rapidly progressing pustular eruption with symptoms of sepsis. These patients were seen immediately, cultures were obtained and empiric antibiotic therapy was initiated. They recovered without long-term complications. Rapid-onset bacterial infections following non-ablative laser resurfacing with the 1550/1927 nm laser have not been previously reported in the literature. The infections can progress quickly and lead to serious sequelae, including systemic illness and severe scarring, if not identified and appropriately treated. We present these cases to highlight the importance of close surveillance and when appropriate, rapid intervention, following non-ablative fractional procedures, especially when patients present with atypical symptoms and signs. PMID:25586939

  1. The role of vascular endothelial growth factor in fractional laser resurfacing with the carbon dioxide laser.

    PubMed

    Jiang, Xia; Ge, Hongmei; Zhou, Chuanqing; Chai, Xinyu; Ren, Qiu Shi

    2012-05-01

    of acute inflammation, fibroblast proliferation and vessel formation induced by fractional CO(2) laser resurfacing. PMID:21960121

  2. Efficacy and Safety of Fractional CO2 Laser Resurfacing in Non-hypertrophic Traumatic and Burn Scars

    PubMed Central

    Majid, Imran; Imran, Saher

    2015-01-01

    Background: Fractional photothermolysis is one of the most effective treatment options used to resurface scars of different aetiologies. Aim: To assess the efficacy and safety of fractional CO2 laser resurfacing treatment in the management of non-hypertrophic traumatic and burn scars. Materials and Methods: Twenty-five patients affected by non-hypertrophic traumatic and burn scars were treated with four sessions of fractional CO2 laser resurfacing treatment at 6-weekly intervals. Patients were photographed at each visit and finally, 3 months after the end of treatment schedule. Response to treatment was assessed clinically as well as by comparing the initial photograph of the patient with the one taken at the last follow-up visit 3-months after the final treatment session. Changes in skin texture, surface irregularity and pigmentation were assessed on a quartile grading scale and scored individually from 0 to 4. A mean of the three individual scores was calculated and the response was labelled as ‘excellent’ if the mean score achieved was >2. A score of 1-2 was labeled as good response while a score below 1 was labeled as ‘poor’ response. The subjective satisfaction of each patient with the treatment offered was also assessed at the last follow-up visit. Results: The commonest site of scarring treated was the face followed by hands. Response to treatment was rated as excellent in 60% (15/25) patients while 24% (6/25) and 16% (4/25) patients were labeled as good and poor responders, respectively. Skin texture showed better response than other variables with average score of 2.44. Linear post-traumatic scars were seen to respond less than other morphological types. Majority of the patients (19 out of 25) were highly satisfied with the treatment offered. No long-term adverse effects were noted in any patient. Conclusions: Fractional photothermolysis with a fractional CO2 laser gives excellent results in patients with post-burn scars with minimal adverse

  3. [Catheter ablation of persistent atrial fibrillation : pulmonary vein isolation, ablation of fractionated electrograms, stepwise approach or rotor ablation?].

    PubMed

    Scherr, D

    2015-02-01

    Catheter ablation is an established treatment option for patients with atrial fibrillation (AF). In paroxysmal AF ablation, pulmonary vein isolation alone is a well-defined procedural endpoint, leading to success rates of up to 80% with multiple procedures over 5 years of follow-up. The success rate in persistent AF ablation is significantly more limited. This is partly due to the rudimentary understanding of the substrate maintaining persistent AF. Three main pathophysiological concepts for this arrhythmia exist: the multiple wavelet hypothesis, the concept of focal triggers, mainly located in the pulmonary veins and the rotor hypothesis. However, the targets and endpoints of persistent AF ablation are ill-defined and there is no consensus on the optimal ablation strategy in these patients. Based on these concepts, several ablation approaches for persistent AF have emerged: pulmonary vein isolation, the stepwise approach (i.e. pulmonary vein isolation, ablation of fractionated electrograms and linear ablation), magnetic resonance imaging (MRI) and rotor-based approaches. Currently, persistent AF ablation is a second-line therapy option to restore and maintain sinus rhythm. Several factors, such as the presence of structural heart disease, duration of persistent AF and dilatation and possibly also the degree of fibrosis of the left atrium should influence the decision to perform persistent AF ablation. PMID:25687615

  4. Efficacy of Punch Elevation Combined with Fractional Carbon Dioxide Laser Resurfacing in Facial Atrophic Acne Scarring: A Randomized Split-face Clinical Study

    PubMed Central

    Faghihi, Gita; Nouraei, Saeid; Asilian, Ali; Keyvan, Shima; Abtahi-Naeini, Bahareh; Rakhshanpour, Mehrdad; Nilforoushzadeh, Mohammad Ali; Hosseini, Sayed Mohsen

    2015-01-01

    Background: A number of treatments for reducing the appearance of acne scars are available, but general guidelines for optimizing acne scar treatment do not exist. The aim of this study was to compare the clinical effectiveness and side effects of fractional carbon dioxide (CO2) laser resurfacing combined with punch elevation with fractional CO2 laser resurfacing alone in the treatment of atrophic acne scars. Materials and Methods: Forty-two Iranian subjects (age range 18–55) with Fitzpatrick skin types III to IV and moderate to severe atrophic acne scars on both cheeks received randomized split-face treatments: One side received fractional CO2 laser treatment and the other received one session of punch elevation combined with two sessions of laser fractional CO2 laser treatment, separated by an interval of 1 month. Two dermatologists independently evaluated improvement in acne scars 4 and 16 weeks after the last treatment. Side effects were also recorded after each treatment. Results: The mean ± SD age of patients was 23.4 ± 2.6 years. Clinical improvement of facial acne scarring was assessed by two dermatologists blinded to treatment conditions. No significant difference in evaluation was observed 1 month after treatment (P = 0.56). Their evaluation found that fractional CO2 laser treatment combined with punch elevation had greater efficacy than that with fractional CO2 laser treatment alone, assessed 4 months after treatment (P = 0.02). Among all side effects, coagulated crust formation and pruritus at day 3 after fractional CO2 laser treatment was significant on both treatment sides (P < 0.05). Conclusion: Concurrent use of fractional laser skin resurfacing with punch elevation offers a safe and effective approach for the treatment of acne scarring. PMID:26538695

  5. Next generation Er:YAG fractional ablative laser

    NASA Astrophysics Data System (ADS)

    Heinrich, A.; Vizhanyo, A.; Krammer, P.; Summer, S.; Gross, S.; Bragagna, T.; Böhler, C.

    2011-03-01

    Pantec Biosolutions AG presents a portable fractional ablative laser system based on a miniaturized diode pumped Er:YAG laser. The system can operate at repetition rates up to 500 Hz and has an incorporated beam deflection unit. It is smaller, lighter and cost efficient compared to systems based on lamp pumped Er:YAG lasers and incorporates a skin layer detection to guarantee precise control of the microporation process. The pulse parameters enable a variety of applications in dermatology and in general medicine, as demonstrated by first results on transdermal drug delivery of FSH (follicle stimulating hormone).

  6. Combination ALA-PDT and Ablative Fractional Er:YAG Laser (2,940 nm) on the Treatment of Severe Acne

    PubMed Central

    Yin, Rui; Lin, Lin; Xiao, Yan; Hao, Fei; Hamblin, Michael R.

    2014-01-01

    Background Scarring is a very common complication of severe acne and is difficult to treat by conventional methods. 5-Aminolevulinic acid (ALA) photodynamic therapy (PDT) is a novel treatment for improving acne lesions. Fractional laser resurfacing is a promising treatment for scar treatment because of its unique ability to stimulate the wound healing response and its depth of penetration. Objective To evaluate the efficacy of combination therapies of ALA-PDT and ablative fractional Er:YAG laser (2,940 nm) for scarring lesions in severe acne patients. Methods A prospective, single-arm, pilot study. Forty subjects with severe acne were treated with 15% ALA-PDT for four times at 10-day intervals. They then received ablative fractional Er:YAG laser treatment five times at 4-week intervals. Three independent investigators evaluated subject outcomes at 1, 3, 6, and 12 months post-treatment (primary outcome); patients also provided self-assessments of improvement (secondary outcome). Results Significant reductions in acne score (P<0.01) were obtained at follow-up visits after 1, 3, 6, and 12 months. After 6 month, the lesions showed overall improvement in all of subjects (good to excellent in acne inflammatory lesions), 80% overall improvement in acne scars. After 12 months, most of subjects had improved hypertrophic/atrophic scars (good to excellent in 85%) and no one had recurrent acne inflammatory lesions. Patient self-evaluation also revealed good to excellent improvements (on average) in acne lesions and scarring, with significant improvements in self-esteem after 6 months post-treatment. Conclusions PDT can control the inflammation and improve the severity of acne lesions. Fractional resurfacing is a promising new treatment modality for scars by stimulating wound healing and remodeling. The combination therapy is a promising option for severe acne to prevent and improve car formation. PMID:24391075

  7. A tectonic resurfacing model for Venus

    NASA Technical Reports Server (NTRS)

    Solomon, Sean C.

    1993-01-01

    Two remarkable aspects of the population of impact craters on Venus are that craters at all sizes are indistinguishable from a random population and that the vast majority of craters have not been significantly modified by tectonic strain or by volcanic flows external to the crater rim, despite evidence from Magellan images that volcanic and tectonic features are widespread on Venus. One interpretation of these observations is that most of the surface dates from the end of a catastrophic global resurfacing event that ceased about 500 My ago, and that the small fraction of craters volcanically embayed or modified by deformation indicates that volcanic and tectonic activity subsequent to that time has been at much lower levels. An alternative model, in which resurfacing occurs episodically in patches a few hundred kilometers in extent and there is a wider spectrum of surface ages, also appears to be consistent with the characteristics of impact craters on Venus. A number of potential mechanisms for catastrophic resurfacing of Venus have been proposed, ranging from geologically sudden convective destabilization of the global lithosphere to strongly time-dependent heat flux and melt generation in the underlying mantle. In most of these geophysical models, resurfacing occurs implicitly or explicitly by volcanism. We explore the hypothesis that, at least in the geologically recent history of Venus, the primary resurfacing mechanism has been tectonic deformation rather than volcanism. We show how such a hypothesis provides at least as good an explanation of a wide range of observations as do volcanic resurfacing models. Finally, we explore the implications of tectonic resurfacing hypothesis for the controversy over the recent resurfacing history of the planet.

  8. Current Laser Resurfacing Technologies: A Review that Delves Beneath the Surface

    PubMed Central

    Preissig, Jason; Hamilton, Kristy; Markus, Ramsey

    2012-01-01

    Numerous laser platforms exist that rejuvenate the skin by resurfacing its upper layers. In varying degrees, these lasers improve the appearance of lentigines and rhytides, eliminate photoaging, soften scarring due to acne and other causes, and treat dyspigmentation. Five major classes of dermatologic lasers are currently in common use: ablative and nonablative lasers in both fractionated and unfractionated forms as well as radiofrequency technologies. The gentler nonablative lasers allow for quicker healing, whereas harsher ablative lasers tend to be more effective. Fractionating either laser distributes the effect, increasing the number of treatments but minimizing downtime and complications. In this review article, the authors seek to inform surgeons about the current laser platforms available, clarify the differences between them, and thereby facilitate the identification of the most appropriate laser for their practice. PMID:23904818

  9. Microstructural and molecular considerations in the treatment of scars with ablative fractional lasers.

    PubMed

    Giordano, Cerrene N; Ozog, David

    2015-03-01

    Fractional ablative lasers have recently proven to be an effective modality for improving the clinical appearance and minimizing the morbidity associated with restrictivetype scars. Their tolerable safety profile on nonfacial sites and darker Fitzpatrick skin types provides an advantage over its fully ablative counterpart in treating facial rhytides, photodamaged skin, and acne scars. However, despite its increasing usage in clinical practice, the mechanism behind the observed clinical benefit remains complex and has yet to be fully elucidated. This paper reviews the work on the histological mechanism of action of ablative fractional lasers, and the molecular changes that occur posttreatment on restrictive scars, with an emphasis on mature burn and postsurgical scars. As the majority of research has been on the carbon dioxide laser, a natural focus on this wavelength is presented. PMID:25922951

  10. Photodynamic Therapy with Ablative Carbon Dioxide Fractional Laser in Treatment of Actinic Keratosis

    PubMed Central

    Jang, Yong Hyun; Lee, Dong Jun; Shin, Jaeyoung; Kang, Hee Young; Lee, Eun-So

    2013-01-01

    Background Recently, photodynamic therapy (PDT) has been shown to be an effective first-line treatment for actinic keratosis (AK). However, a major limitation of PDT is the long incubation time required to allow penetration of the photosensitizer. Objective The aim of this study was to assess if pretreatment with an ablative carbon dioxide (CO2) fractional laser can reduce the incubation time of the photosensitizer. Methods Initially, 29 patients with a total of 34 AK lesions were treated with an ablative CO2 fractional laser at Ajou University Hospital between January and December 2010. Immediately after the laser treatment, topical 20% 5-aminolevulinic acid or methyl-aminolevulinate was applied to the AK lesions and incubated for 70 to 90 minutes. Then, the treated areas were illuminated with a red light source. Improvement was clinically or histologically assessed eight weeks after the treatment. Results In spite of the short incubation time, 24 lesions (70.6%) showed a complete response (CR) within three sessions of PDT (10 lesions a clinical CR and 14 lesions a clinical/histological CR). There were no significant side effects associated with the combination of ablative CO2 fractional laser and PDT. Conclusion Ablative CO2 fractional laser may be considered an additional treatment option for reducing the incubation time of the photosensitizer in PDT. PMID:24371387

  11. Hip Resurfacing Implants.

    PubMed

    Cadossi, Matteo; Tedesco, Giuseppe; Sambri, Andrea; Mazzotti, Antonio; Giannini, Sandro

    2015-08-01

    EDUCATIONAL OBJECTIVES As a result of reading this article, physicians should be able to: 1. Describe the advantages of hip resurfacing. 2. Describe the disadvantages of hip resurfacing. 3. Identify the population in which hip resurfacing is most often indicated. 4. Demonstrate how to properly postoperatively manage patients with metal-on-metal prostheses. Hip resurfacing offers a suitable solution for young patients affected by hip disease who have high function demands and good bone quality. Bone stock preservation, restoration of the normal proximal femur anatomy, the lack of stress shielding, and the possibility of resuming sporting activity are proven advantages of hip resurfacing. However, there are some disadvantages, such as fracture of the femoral neck, onset of neck narrowing, and possible complications due to the metal-on-metal bearings, including pseudotumors, peri-implant osteolysis, and chronic elevation of metal ions in serum levels. Recent data suggest that the ideal candidate for hip resurfacing is an active male, younger than 65 years, with primary or posttraumatic osteoarthritis, and with a femoral head diameter larger than 50 to 54 mm. Based on these selection criteria, the literature reports implant survival to be similar to that of total hip arthroplasty. The current authors' experience confirms a low failure rate and excellent functional outcomes, with metal ion serum levels becoming stable over time in well-functioning implants. Proper surgical technique, correct patient selection, and the right choice of a well-established prosthetic model are essential elements for the long-term success of these implants. PMID:26270748

  12. Elemental fractionation in 785 nm picosecond and femtosecond laser ablation inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Shaheen, M. E.; Gagnon, J. E.; Fryer, B. J.

    2015-05-01

    Elemental fractionation and ICP-MS signal response were investigated for two different pulse width laser beams originating from the same laser system. Femtosecond and picosecond laser beams at pulse widths of 130 fs and 110 ps, respectively, and wavelength of 785 nm were used to ablate NIST 610 synthetic glass and SRM 1107 Naval Brass B at the same spot for 800 to 1000 laser pulses at different repetition rates (5 to 50 Hz). Elemental fractionation was found to depend on repetition rate and showed a trend with femtosecond laser ablation that is opposite to that observed in picosecond laser ablation for most measured isotopes. ICP-MS signal intensity was higher in femtosecond than picosecond LA-ICP-MS in both NIST 610 and naval brass when ablation was conducted under the same fluence and repetition rate. The differences in signal intensity were partly related to differences in particle size distribution between particles generated by femtosecond and picosecond laser pulses and the consequent differences in transport and ionization efficiencies. The main reason for the higher signal intensity resulting from femtosecond laser pulses was related to the larger crater sizes compared to those created during picosecond laser ablation. Elemental ratios measured using 66Zn/63Cu, 208Pb/238U, 232Th/238U, 66Zn/232Th and 66Zn/208Pb were found to change with the number of laser pulses with data points being more scattered in picosecond than femtosecond laser pulses. Reproducibility of replicate measurements of signal intensities, fractionation and elemental ratios was better for fs-LA-ICP-MS (RSD ~ 3 to 6%) than ps-LA-ICP-MS (RSD ~ 7 to 11%).

  13. Photodynamic Therapy with Ablative Carbon Dioxide Fractional Laser for Treating Bowen Disease

    PubMed Central

    Kim, Sue Kyung; Park, Ji-Youn; Song, Hyo Sang; Kim, You-Sun

    2013-01-01

    Background Topical photodynamic therapy (PDT) has been increasingly used to treat malignant skin tumors including the Bowen disease. However, patients could be displeased with the long incubation time required for conventional PDT. Objective We evaluated the efficacy and safety of PDT with a short incubation time of ablative CO2 fractional laser pretreatment for treating Bowen disease. Methods Ten patients were included. Just before applying the topical photosensitizer, all lesions were treated with ablative CO2 fractional laser, following the application of methyl aminolevulinate and irradiation with red light (Aktilite CL 128). Histological confirmation, rebiopsy, and clinical assessments were performed. Adverse events were also recorded. Results Five of the ten (50%) lesions showed a complete response (CR) within three PDT sessions. After four treatment sessions, all lesions except one penile shaft lesion (90%) achieved clinical and histological CR or clinical CR only. The average number of treatments to CR was 3.70±1.70. The treatments showed favorable cosmetic outcomes and no serious adverse events. Conclusion The results suggest that pretreatment with an ablative fractional CO2 laser before PDT has similar treatment efficacy and requires a shorter photosensitizer incubation time compared with the conventional PDT method. PMID:24003277

  14. Micro-scale novel stable isotope fractionation during weathering disclosed by femtosecond laser ablation

    NASA Astrophysics Data System (ADS)

    Schuessler, J. A.; von Blanckenburg, F.

    2012-12-01

    The stable isotope fractionation of metals and metalloids during chemical weathering and alteration of rocks at low temperature is a topic receiving increasing scientific attention. For these systems, weathering of primary minerals leads to selective partitioning of isotopes between the secondary minerals formed from them, and the dissolved phase of soil or river water. While the isotopic signatures of these processes have been mapped-out at the catchment or the soil scale, the actual isotopic fractionation is occurring at the mineral scale. To identify the processes underlying such micro-scale fractionation, the development of micro-analytical tools allows to investigate mechanisms of isotope fractionation in-situ, in combination with textural information of weathering reactions. We have developed a second-generation UV femtosecond (fs) laser system at GFZ Potsdam. The advantage of UV-fs laser ablation is the reduction of laser-induced isotopic and elemental fractionation by avoiding 'thermal effects' during ablation, such that accurate isotope ratios can be measured by standard-sample-standard bracketing using laser ablation multicollector ICP-MS; where the matrix of the bracketing standard does not need to match that of the sample [1]. Our system consists of the latest generation femtosecond solid-state laser (Newport Spectra Physics Solstice), producing an ultra short pulse width of about 100 femtoseconds at a wavelength of 196 nm. The system is combined with a custom-build computer-controlled sample stage and allows fully automated isotope analyses through synchronised operation of the laser with the Neptune MC-ICP-MS. To assess precision and accuracy of our laser ablation method, we analysed various geological reference materials. We obtained δ30Si values of -0.31 ± 0.23 (2SD, n = 13) for basalt glass BHVO-2G, and -1.25 ± 0.21 (2SD, n = 27) for pure Si IRMM17 when bracketed against NBS-28 quartz. δ56Fe and δ26Mg values obtained from non-matrix matched

  15. New postlaser resurfacing medical treatment

    NASA Astrophysics Data System (ADS)

    Longo, Leonardo; Postiglione, Marco

    2000-06-01

    Today, laser resurfacing technique is codified. The purpose of our study is to reduce the post-intervention discomfort and the clinical signs. We tested a combination of pharmacological substances, applied as spray lotion and gel during and immediately after the intervention and the days after. We used this substances after laser resurfacing done with CO2 laser, Er:YAG laser and both. We noted a reduction statistically significant of the signs up described, with reduction of the recovery time. It is our opinion that this medical treatment must be done always, during and post laser resurfacing treatment.

  16. Anesthesia Methods in Laser Resurfacing

    PubMed Central

    Gaitan, Sergio; Markus, Ramsey

    2012-01-01

    Laser resurfacing technology offers the ability to treat skin changes that are the result of the aging process. One of the major drawbacks of laser resurfacing technologies is the pain associated with the procedure. The methods of anesthesia used in laser resurfacing to help minimize the pain include both noninvasive and invasive procedures. The noninvasive procedures can be divided into topical, cryoanesthesia, and a combination of both. The invasive methods of anesthesia include injected forms (infiltrative, nerve blocks, and tumescent anesthesia) and supervised anesthesia (monitored anesthesia care and general anesthesia). In this review, the authors summarize the types of anesthesia used in laser resurfacing to aid the provider in offering the most appropriate method for the patient to have as painless a procedure as possible. PMID:23904819

  17. A novel 1565 nm non-ablative fractional device for stretch marks: A preliminary report

    PubMed Central

    Tretti Clementoni, Matteo; Lavagno, Rosalia

    2015-01-01

    Abstract Background: Striae Distensae (SD) is a very common dermatologic condition. We evaluated the effectiveness and safety of a novel non-ablative fractional 1565 nm laser (ResurFX) on the appearance of SD. Materials and methods: Twelve Caucasian subjects with various stages of SD received three non-ablative laser treatments. Each treatment consisted of two different laser settings, in order to achieve a demarcated dense impact together with a diffused deep impact. Three months after the last treatment, SD improvement was assessed by blinded and non-blinded reviewers using clinical images and 3D image analyses. Results: Good clinical improvement (between 51% and 75%) was observed in all patients. Most patients showed improvement of > 50% in the volume of depressions and in lesion color (91.7% and 83.3% of patients, respectively). The average pain during treatment was generally defined as tolerable and the average downtime was 4 days. Transient erythema and severe edema were noted immediately after the procedure, but long-lasting or severe adverse effects were not observed. All patients noted a good improvement and were satisfied with the treatment and the results. Conclusions: The treatment with the 1565 nm ResurFX laser resulted in improved pigmentation, volume, and textural appearance of SD. PMID:25633176

  18. In vivo confocal imaging of epidermal cell migration and dermal changes post nonablative fractional resurfacing: study of the wound healing process with corroborated histopathologic evidence

    NASA Astrophysics Data System (ADS)

    Stumpp, Oliver F.; Bedi, Vikramaditya P.; Wyatt, Danica; Lac, Diana; Rahman, Zakia; Chan, Kin F.

    2009-03-01

    In vivo wound healing response post nonablative fractional laser treatment is evaluated. Seven healthy subjects receive treatments with a Fraxel re:store™ laser system on the forearm with pulse energies ranging from 10 to 70 mJ. The treatment sites are imaged at 1-h increments up to 40 h using confocal microscope z-stacks using 10-μm-depth spacing. At least five individual microscopic treatment zones are imaged per subject, time point, and treatment energy. Images are analyzed for tissue structure and morphology to classify each lesion as healed or not healed, depending on epidermal re-epithelialization at each time point and treatment energy. Probit analysis is used to statistically determine the ED50 and ED84 probabilities for a positive dose response (healed lesion) as a function of treatment energy. Confocal observations reveal epidermal keratinocyte migration patterns confirmed with histological analysis using hematoxylin and eosin (HE) and lactate dehydrogenase (LDH) staining at 10 mJ at 0, 7, 16, and 24-h post-treatment. Results indicate that more time is required to conclude re-epithelialization with larger lesion sizes (all less than 500 μm) corresponding to higher treatment energies. For the entire pulse energy range tested, epidermal re-epithelialization concludes between 10 to 22-h post-treatment for ED50 and 13 to 28 h for ED84.

  19. A novel thermo-mechanical system enhanced transdermal delivery of hydrophilic active agents by fractional ablation.

    PubMed

    Sintov, Amnon C; Hofmann, Maja A

    2016-09-25

    The Tixel is a novel device based on a thermo-mechanical ablation technology that combines a sophisticated motion and a temperature control. The fractional technology is used to transfer a very precise thermal energy to the skin thereby creating an array of microchannels, accompanying by no signs of pain or inconvenience. This study aimed to evaluate the effect of the Tixel on the skin permeability of three hydrophilic molecular models: verapamil hydrochloride, diclofenac sodium, and magnesium ascorbyl phosphate. Tixel's gold-platted stainless steel tip heated to a temperature of 400°C was applied on skin for 8ms or 9ms at a protrusion of 400μm (the distance in which the tip protrudes beyond the distance gauge). The experiments were carried out partly in vivo in humans using a fluorescent dye and a confocal microscopy and partly in vitro using porcine skin and a Franz diffusion cell system. The results obtained in this study have shown that (a) no significant collateral damage to the skin tissue and no necrosis or dermal coagulation have been noted, (b) the microchannels remained open and endured for at least 6h, and (c) the skin permeability of hydrophilic molecules, which poorly penetrate the lipophilic stratum corneum barrier, was significantly enhanced by using Tixel's pretreatment. PMID:27480396

  20. Adjusted Left Atrial Emptying Fraction as a Predictor of Procedural Outcome after Catheter Ablation for Atrial Fibrillation

    PubMed Central

    Im, Sung Il; Kim, Sun Won; Choi, Cheol Ung; Kim, Jin Won; Yong, Hwan Seok; Kim, Eung Ju; Rha, Seung-Woon; Park, Chang Gyu; Seo, Hong Seog; Oh, Dong Joo; Lim, Hong Euy

    2015-01-01

    Structural remodeling of the left atrium is a risk factor for recurrent arrhythmia after catheter ablation for atrial fibrillation; however, data are sparse regarding the role of functional left atrial remodeling in predicting procedural outcomes. We evaluated whether left atrial transport function could be used to predict recurrent atrial fibrillation. From July 2008 through August 2010, we enrolled 202 consecutive patients who underwent catheter ablation for atrial fibrillation (paroxysmal=120, persistent=82). Left atrial volumes (LAVs) were measured by means of multislice computed tomography at every 10% of the R-R interval, and measurements were adjusted for body surface area to yield the LAV index (LAVI) at baseline. The left atrial emptying fraction (LAEF) was calculated according to LAV differences. During the mean follow-up period of 10 ± 4 months after a single ablation procedure, atrial fibrillation recurred in 59 patients (paroxysmal=19, persistent=40). Multivariate analysis revealed that persistent atrial fibrillation, early mitral inflow velocity, LAVImax, LAVImin, LAEF, LAVImax/LAEF, and LAVImin/LAEF were all independent predictors of atrial fibrillation, but the best predictor was LAVImin/LAEF (β=1.329, P=0.001). The cutoff value was 1.61 (mL/m2)/%, and the sensitivity and specificity were 74.6% and 62.2%, respectively (area under the curve=0.761). Our study shows that adjusted left atrial emptying fraction with use of multislice computed tomography might be a useful, noninvasive method to select patients for ablation. PMID:26175632

  1. In vivo histological evaluation of fractional ablative microplasma radio frequency technology using a roller tip: an animal study.

    PubMed

    Li, Xiaodan; Fang, Lin; Huang, Luping

    2015-12-01

    The aim of the present study is to investigate the histological characteristics associated with microplasma radio frequency (MPRF) technology in an animal study using different treatment parameters. Two white piglets, aged 6 months, received MPRF treatment using a roller tip; the treatment site was located on the dorsal skin. Four groups of parameters were adopted regarding the performance of the treatment at four zones on the dorsum. Immediately, at 7 days and at 1, 3, and 6 months posttreatment, we observed the healing process and obtained specimens from each treatment zone. Hematoxylin and eosin and Masson stainings of histological sections were performed to assess the degree of tissue injury, the heat effect, the healing process, and neocollagenesis. Heat shock protein (HSP) was also detected using immunohistochemistry. The roller tip generated a fractional treatment, which had a general trend involving an increase in depth and width with increasing pulse energy and decreasing sliding speed. During the wound healing process, dermal neocollagenesis was stimulated, remodeled, and matured gradually. The expression of HSP47 and HPS72 was elevated in the dermis surrounding the microlesions after treatment; it peaked at 1 month posttreatment and became diffuse in the dermis. MPRF is a promising fractional skin resurfacing technique. The roller tip can be used with low risk in the entire treatment zone with rapid healing. An appropriate treatment regimen should be chosen to guarantee therapeutic efficacy and safety. PMID:26396104

  2. A case of successfully treated recalcitrant EGFR inhibitor-induced acneiform eruption following non-ablative fractional laser.

    PubMed

    Choi, Joong Woon; Kim, Tae In; Jeong, Ki-Heon; Shin, Min Kyung

    2016-07-01

    Epidermal growth factor receptor (EGFR) inhibitor, a targeted therapy in the field of oncology, is a new drugs suggested for the cause of acneiform eruptions. The unresponsiveness to conventional acne therapy is a pivotal reason of seeking alternatives to treat drug-induced acneiform eruptions. A 30-year-old female treated with cetuximab, EGFR inhibitor presented with numerous sized erythematous papules and pustules on her face. All responses of oral medications and topical application were poor. She was treated with two passes of non-ablative 1550 nm fractional erbium glass laser with topical clindamycin. After three laser sessions, the skin lesions improved dramatically without any side effects. There is currently no single effective treatment for acneiform eruption. This report shed light on the possibility that non-ablative fractional laser can be an alternative for recalcitrant drug-induced acneiform eruptions. PMID:27146102

  3. Fractional Erbium laser in the treatment of photoaging: randomized comparative, clinical and histopathological study of ablative (2940nm) vs. non-ablative (1540nm) methods after 3 months*

    PubMed Central

    Borges, Juliano; Cuzzi, Tullia; Mandarim-de-Lacerda, Carlos Alberto; Manela-Azulay, Mônica

    2014-01-01

    BACKGROUND Fractional non-ablative lasers keep the epidermis intact, while fractional ablative lasers remove it, making them theoretically more effective. OBJECTIVES To evaluate the clinical and histological alterations induced by fractional photothermolysis for treating photoaging, comparing the possible equivalence of multiple sessions of 1540nm Erbium, to one session of 2940nm Erbium. METHODS Eighteen patients (mean age 55.9) completed the treatment with three sessions of 1540nm fractional Erbium laser on one side of the face (50 mJ/mB, 15ms, 2 passes), and one session of 2940nm on the other side (5mJ/mB, 0.25ms, 2 passes). Biopsies were performed before and 3 months after treatment. Clinical, histological and morphometric evaluations were carried out. RESULTS All patients presented clinical improvement with no statistically significant difference (p> 0.05) between the treated sides. Histopathology revealed a new organization of collagen and elastic fibers, accompanied by edema, which was more evident with the 2940nm laser. This finding was confirmed by morphometry, which showed a decrease in collagen density for both treatments, with a statistical significance for the 2940nm laser (p > 0.001). CONCLUSIONS Three 1540nm sessions were clinically equivalent to one 2940nm session. The edema probably contributed to the positive results after three months, togheter with the new collagen and elastic fibers organization. The greater edema after the 2940nm session indicates that dermal remodeling takes longer than with 1540nm. It is possible that this histological superiority relates to a more prolonged effect, but a cohort longer than three months is needed to confirm that supposition. PMID:24770501

  4. Recontouring, resurfacing, and scar revision in skin cancer reconstruction.

    PubMed

    Brenner, Michael J; Perro, Christopher A

    2009-08-01

    Residual disfigurement is a common problem for patients who have undergone skin cancer reconstruction. Restoring form and function in these patients is an artistic and technical endeavor. The efficacy of surgical scar revision, dermabrasion, chemical peels, and laser resurfacing is predicated upon the skin's innate ability to regenerate over time in response to mechanical, chemical, and thermal or ablative stresses. The patient and surgeon should be accepting of a process that is often gradual and may proceed in stages. Achieving proficiency with the secondary procedures for improving scars and local flaps may allow the motivated surgeon to mold an initially passable surgical result into an excellent one. PMID:19698924

  5. Endometrial ablation

    MedlinePlus

    Hysteroscopy-endometrial ablation; Laser thermal ablation; Endometrial ablation-radiofrequency; Endometrial ablation-thermal balloon ablation; Rollerball ablation; Hydrothermal ablation; Novasure ablation

  6. Non-ablative fractional laser assists cutaneous delivery of small- and macro-molecules with minimal bacterial infection risk.

    PubMed

    Lee, Woan-Ruoh; Shen, Shing-Chuan; Aljuffali, Ibrahim A; Lin, Yin-Ku; Huang, Chang-Wei; Fang, Jia-You

    2016-09-20

    Use of the ablative laser has been approved to enhance topical drug penetration. Investigation into the usefulness of the non-ablative laser for assisting drug delivery is very limited. In this study, we explored the safety and efficacy of the non-ablative fractional erbium:glass (Er:glass) laser as an enhancement approach to promote drug permeation. Both pig and nude mouse skins were employed as transport barriers. We histologically examined the skin structure after laser exposure. The permeants of 5-aminolevulinic acid (ALA), imiquimod, tretinoin, peptide, dextrans and quantum dots (QD) were used to evaluate in vitro and in vivo skin passage. The fractional laser selectively created an array of photothermal dots deep into the dermis with the preservation of the stratum corneum and epidermis. The barrier function of the skin could be recovered 8-60h post-irradiation depending on the laser spot densities. The application of the laser caused no local infection of Staphylococcus aureus and Pseudomonas aeruginosa. Compared to intact skin, ALA flux was enhanced up to 1200-fold after laser exposure. The penetration enhancement level by the laser was decreased following the increase of permeant lipophilicity. The skin accumulation of tretinoin, an extremely lipophilic drug, showed only a 2-fold elevation by laser irradiation. The laser promoted peptide penetration 10-fold compared to the control skin. Skin delivery of dextrans with a molecular weight (MW) of at least 40kDa could be achieved with the Er:glass laser. QD with a diameter of 20nm penetrated into the skin with the assistance of the non-ablative laser. The confocal microscopic images indicated the perpendicular and lateral diffusions of dextrans and nanoparticles via laser-created microscopic thermal zones. Controlled Er:glass laser irradiation offers a valid enhancement strategy to topically administer the permeants with a wide MW and lipophilicity range. PMID:27345564

  7. Skin resurfacing procedures: new and emerging options

    PubMed Central

    Loesch, Mathew M; Somani, Ally-Khan; Kingsley, Melanie M; Travers, Jeffrey B; Spandau, Dan F

    2014-01-01

    The demand for skin resurfacing and rejuvenating procedures has progressively increased in the last decade and has sparked several advances within the skin resurfacing field that promote faster healing while minimizing downtime and side effects for patients. Several technological and procedural skin resurfacing developments are being integrated into clinical practices today allowing clinicians to treat a broader range of patients’ skin types and pathologies than in years past, with noteworthy outcomes. This article will discuss some emerging and developing resurfacing therapies and treatments that are present today and soon to be available. PMID:25210469

  8. Release of monocyte migration signals by breast cancer cell lines after ablative and fractionated γ-irradiation

    PubMed Central

    2014-01-01

    Background Radiotherapy, administered in fractionated as well as ablative settings, is an essential treatment component for breast cancer. Besides the direct tumor cell death inducing effects, there is growing evidence that immune mechanisms contribute - at least in part - to its therapeutic success. The present study was designed to characterize the type and the extent of cell death induced by fractionated and ablative radiotherapy as well as its impact on the release of monocyte migration stimulating factors by dying breast cancer cells. Methods Cell death and senescence assays were employed to characterize the response of a panel of breast cancer cell lines with different receptor and p53 status towards γ-irradiation applied in a fractionated (daily doses of 2 Gy) or ablative setting (single dose of 20 Gy). Cell-free culture supernatants were examined for their monocyte migration stimulating potential in transwell migration and 2D chemotaxis/chemokinesis assays. Irradiation-induced transcriptional responses were analyzed by qRT-PCR, and CD39 surface expression was measured by flow cytometry. Results Fast proliferating, hormone receptor negative breast cancer cell lines with defective p53 predominantly underwent primary necrosis in response to γ-irradiation when applied at a single, ablative dose of 20 Gy, whereas hormone receptor positive, p53 wildtype cells revealed a combination of apoptosis, primary, and secondary (post-apoptotic) necrosis. During necrosis the dying tumor cells released apyrase-sensitive nucleotides, which effectively stimulated monocyte migration and chemokinesis. In hormone receptor positive cells with functional p53 this was hampered by irradiation-induced surface expression of the ectonucleotidase CD39. Conclusions Our study shows that ablative radiotherapy potently induces necrosis in fast proliferating, hormone receptor negative breast cancer cell lines with mutant p53, which in turn release monocyte migration and chemokinesis

  9. Clinical applications of CO2 laser resurfacing in the treatment of various pathologic skin disorders

    NASA Astrophysics Data System (ADS)

    Giler, Shamai

    1997-12-01

    CO2 laser skin resurfacing devices are widely used in cosmetic surgery for the treatment of facial rhytides, acne scars and aging skin. This technique is also useful in the treatment of various benign and premalignant or multiple pathological skin conditions and disorders originating in the epidermal, dermal and skin appendages, vascular lesions, epidermal nevi, infected wounds and ulcers, and keloids. Various surgical techniques have been developed in our clinic using laser resurfacing in the treatment of more than 2,000 patients with various skin pathologic disorders. We describe our experience with the various techniques used. The precise depth control and ablation properties combined with the hemostatic and sterilizing effects of the CO2 laser beam, reduction of the possibility of bleeding, infection and damage to healthy tissues, make the CO2 laser resurfacing techniques the treatment of choice for cosmetic surgery and treatment of benign, premalignant and multiple pathologic skin conditions.

  10. Observation of in vivo morphologic changes after carbon dioxide ablative fractional laser in a mouse model using noninvasive imaging modalities and comparison with histologic examination.

    PubMed

    Yoo, Kwang Ho; Kwon, Tae Rin; Kim, So Young; Song, Yi Seop; Cheon, Young Sook; Kim, Yu Mi; Yeo, In Kwon; Ko, Eun Jung; Li, Kapsok; Kim, Myeung Nam; Kim, Beom Joon

    2014-01-01

    Ablative fractional carbon dioxide (CO2) lasers have been widely used for several types of cosmetic dermatosis. A number of previous studies have evaluated this technique in animals or human beings by observing morphologic changes using an invasive modality such as skin biopsy. In this study, we assessed in vivo skin changes after CO2 ablative fractional laser treatment in a mouse model using noninvasive imaging modalities (Folliscope(®) and Visioscan 98(®)), and each results was compared with data from histologic examination. An ablative fractional CO2 laser was applied with different pulse energy between 7 to 35 mJ/microspot. As results of above methods, we also confirmed that the CO2 ablative fractional laser generated injuries with increasing width and depth with increasing pulse energy. Although numerous papers have described application of this laser in vivo skin specimens, our study evaluated the feasibility of using relative noninvasive imaging modalities for assessing the outcome of laser ablation. Based on our data, we suggest that these technologies may be useful alternative modalities for assessing laser ablation that are easier to perform and less invasive than skin biopsy. PMID:25041574

  11. Current chemical peels and other resurfacing techniques.

    PubMed

    Mangat, Devinder S; Tansavatdi, Kristina; Garlich, Paul

    2011-02-01

    The currently available methods for resurfacing will be addressed in this article, which has been divided into three areas of focus: chemical peels, lasers, and dermabrasion. Emphasis will be placed on chemical peels, a technique with a long history that provides a very reliable method of resurfacing and that every facial plastic surgeon should be familiar with. PMID:21246455

  12. Facial Resurfacing With Coblation Technology

    PubMed Central

    Weber, Stephen M.; Downs, Brian W.; Ferraz, Mario B.J.; Wang, Tom D.; Cook, Ted A.

    2008-01-01

    Objective To describe our experience with coblation technology for facial resurfacing Methods Retrospective chart review of all patients treated with coblation at our institution Results Twenty-four patients (22 female) underwent a total of 29 coblation procedures for aging face (n = 21) or acne scarring (n = 3). The perioral region was the most frequently treated aesthetic subunit (n = 14), followed by the lower eyelid (n = 7). Five patients underwent full-face coblation. Three patients underwent a second coblation procedure for aging face while a single patient with severe acne scarring underwent 3 procedures. Repeat coblation was delayed at least 5 months (mean, 9 months). Seventeen coblation procedures (59%) were performed concurrently with procedures including, but not limited to, injection treatment, rhinoplasty, blepharoplasty, or combined face/necklift; no adverse events occurred. Seven procedures, including a full-face coblation, were performed in the office under local anesthesia and oral sedation without any adverse events. Mean follow-up was 6 months (range, 1 week to 24 months). No complications were observed. All patients were satisfied with the results after their final coblation treatment. Conclusions Facial coblation is a safe and effective treatment modality for facial resurfacing. PMID:18769690

  13. Effects of MTZs parameters during non-ablative fractional photothermolysis treatments: a numerical study

    NASA Astrophysics Data System (ADS)

    Ma, Jing-bo; Zhang, Ji-zhuang

    2010-11-01

    The novel method of non-ablative FP is acknowledged as an effective technique by offering significant clinical improvement while minimal risk of complications. A new time-dependent mathematical model was built up to investigate the photo-thermal interactions during FP treatments. With this model, effects of treatment-affecting parameters, such as diameter, density and energy of the micro laser beam as well as skin cooling, were numerically investigated. Different photo-thermal behaviors with various treatment parameters were particularly discussed, based on which, a novel concept of programmable treatment procedure (PTP) was proposed. With this technique, desired therapeutic outcomes may be obtained from personalized treatments.

  14. Effects of non-ablative fractional erbium glass laser treatment on gene regulation in human three-dimensional skin models.

    PubMed

    Amann, Philipp M; Marquardt, Yvonne; Steiner, Timm; Hölzle, Frank; Skazik-Voogt, Claudia; Heise, Ruth; Baron, Jens M

    2016-04-01

    Clinical experiences with non-ablative fractional erbium glass laser therapy have demonstrated promising results for dermal remodelling and for the indications of striae, surgical scars and acne scars. So far, molecular effects on human skin following treatment with these laser systems have not been elucidated. Our aim was to investigate laser-induced effects on skin morphology and to analyse molecular effects on gene regulation. Therefore, human three-dimensional (3D) organotypic skin models were irradiated with non-ablative fractional erbium glass laser systems enabling qRT-PCR, microarray and histological studies at same and different time points. A decreased mRNA expression of matrix metalloproteinases (MMPs) 3 and 9 was observed 3 days after treatment. MMP3 also remained downregulated on protein level, whereas the expression of other MMPs like MMP9 was recovered or even upregulated 5 days after irradiation. Inflammatory gene regulatory responses measured by the expression of chemokine (C-X-C motif) ligands (CXCL1, 2, 5, 6) and interleukin expression (IL8) were predominantly reduced. Epidermal differentiation markers such as loricrin, filaggrin-1 and filaggrin-2 were upregulated by both tested laser optics, indicating a potential epidermal involvement. These effects were also shown on protein level in the immunofluorescence analysis. This novel standardised laser-treated human 3D skin model proves useful for monitoring time-dependent ex vivo effects of various laser systems on gene expression and human skin morphology. Our study reveals erbium glass laser-induced regulations of MMP and interleukin expression. We speculate that these alterations on gene expression level could play a role for dermal remodelling, anti-inflammatory effects and increased epidermal differentiation. Our finding may have implications for further understanding of the molecular mechanism of erbium glass laser-induced effects on human skin. PMID:26796701

  15. Resurfacing history of Tempe Terra and surroundings

    SciTech Connect

    Frey, H.V. ); Grant, T.D. )

    1990-08-30

    The resurfacing history of the Tempe Terra region is determined using the Neukum and Hiller technique of breaking cumulative frequency curves into separate branches where the curves depart from a standard production curve. We find four surfaces recorded in the heavily cratered portions of Tempe Terra, with crater retention ages N(1) = (242,100), (95,700), (20,800), and (5,500). This is interpreted to indicate three major resurfacing events occurred in this region, ending at N(1) = (95,700), (20,800), and (5,500). The ridged plains on the Tempe Terra plateau have an oldest recorded surface age of (20,400), identical to that of the second resurfacing event recorded in the heavily cratered areas. A single resurfacing of the ridged plains (which may have been a second episode of ridged plains volcanism) occurred at N(1) = (7,800). The knobby plains to the north west and east of Tempe Terra also show a resurfacing at (20,000) and additional events at (5,400) and perhaps (1,600). Mottled plains to the northeast record surfaces with crater retention age (7,500), (5,000), and (3,900), where the first age is determined by a single surviving crater. It appears that the Lunae Planum Age (LPA) (at N(1) = (20,000)) resurfacing event seen elsewhere on mars was widespread and effective in this region. A second widespread event appears to have ended at N(1) = (5,000). The authors estimate the thickness of the resurfacing materials corresponding to the LPA event to be less than 90 m in the heavily cratered areas but 300-500 m in the ridged plains themselves. Later resurfacing materials were generally thicker farther north in the mottled plains (300 m) than in the knobby plains (200 m).

  16. Histopathology of laser skin resurfacing

    NASA Astrophysics Data System (ADS)

    Thomsen, Sharon L.; Baldwin, Bonnie; Chi, Eric; Ellard, Jeff; Schwartz, Jon A.

    1997-05-01

    Pulsed carbon-dioxide laser skin resurfacing is a purportedly 'non-thermal' procedure enjoying wide application as a cosmetic treatment for skin wrinkles. Treatment success has been based on clinical assessments of skin smoothness. Skin lesions (1 cm2) created by one, two or three superimposed carbon-dioxide laser passes were placed on the backs of 28 'fuzzy' Harlan Sprague Dawley rats. The variable laser irradiation parameters included measured energies ranging from 112 to 387/pulse with pulse widths of 65 and 125 microseconds and a repetition rate of 8 Hz. The square, flat laser beam measured 3 mm2 at the focal point. The lesions were collected from 0 to 10 days after treatment for qualitative and quantitative histopathology. Thermal damage and treatment effect tended to increase in severity and, to a lesser extent, depth with increased delivery parameters. In acute lesions, the vacuolated and fragmented, desiccated and thermally coagulated epidermis was partially removed exposing the underlying thermally coagulated dermal collagen and cells. Epidermal and dermal necrosis and slough occurred between 24 to 72 hours after treatment. Epithelial regeneration originated from the adnexa and the lesion edges. Dermal fibrous scar formation began at 5 days below the regenerated epidermis and became more prominent at 7 and 10 days.

  17. Non-ablative fractional laser in conjunction with microneedle arrays for improved cutaneous vaccination

    NASA Astrophysics Data System (ADS)

    Wang, Ji; Li, Bo; Wu, Mei X.

    2015-03-01

    Skin is more potent than the muscle for vaccination, but it is not a common site for immunization to date owing, in part, to a relatively high rate of pains and skin irritation and difficulty of administration. Here, we show effective and lesion free cutaneous vaccination by a combination of a biodegradable microneedle array (MNs) and an FDA-approved nonablative fractional laser (NAFL). Delivering a vaccine into many micropores, instead of a single "big" pore in the skin, effectively segregated vaccine-induced inflammation into many microzones and resulted in quick resolution of the inflammation, provided that distances between any two micropores were far enough. When the inoculation site was treated by NAFL prior to insertion of the MNs comprised of PR8 model influenza vaccine, the mice displayed vigorous antigen-uptake, giving rise to strong, Th1-biased immunity. The mice were protected from a challenge of homologous influenza virus at a high dose as well as heterologous H1N1 and H3N2 viruses. The adjuvant effect of NAFL was ascribed primarily to activation of the dsDNA sensing pathway by dsDNA released from laser-damaged skin cells. Thus, mice deficient in the dsDNA sensing pathway, but not toll like receptor (TLR) or inflammasome pathways, showed poor response to NAFL. Importantly, both mice and swine exhibited strong, protective immunity, but no overt skin reactions with this approach, in sharp contrast to intradermal injections that caused severe, overt skin reactions. The effective lesion-free transcutaneous vaccination merits further clinical studies.

  18. New insight in the treatment of refractory melasma: Laser Q-switched Nd: YAG non-ablative fractionated followed by intense pulsed light.

    PubMed

    Cunha, Paulo Rowilson; Pinto, Clovis Antonio Lopes; Mattos, Camila Bonati; Cabrini, Dayane Peverari; Tolosa, Joana Lugli

    2015-01-01

    The purpose of our study was to verify the results of the association of Q-switched Nd: YAG non-ablative fractionated with intense pulsed light, in order to treat patients with refractory melasma. The combination of these two devices seems to be the best treatment to combat hyperpigmentation produced by melasma, with low occurrence of side effects, which may be justified by the selective photothermolysis at subcellular level. PMID:26032175

  19. Erbium laser resurfacing for actinic cheilitis.

    PubMed

    Cohen, Joel L

    2013-11-01

    Actinic cheilitis is a precancerous condition characterized by grayish-whitish area(s) of discoloration on the mucosal lip, often blunting the demarcation between mucosa and cutaneous lip. Actinic cheilitis is considered to be an early part of the spectrum of squamous cell carcinoma. Squamous cell carcinoma specifically of the lip has a high rate of recurrence and metastasis through the oral cavity leading to a poor overall survival. Risk factors for the development of actinic cheilitis include chronic solar irradiation, increasing age, male gender, light skin complexion, immunosuppression, and possibly tobacco and alcohol consumption. Treatment options include topical pharmacotherapy (eg, fluorouracil, imiquimod) or procedural interventions (eg, cryotherapy, electrosurgery, surgical vermillionectomy, laser resurfacing), each with their known advantages and disadvantages. There is little consensus as to which treatment options offer the most clinical utility given the paucity of comparative clinical data. In my practice, laser resurfacing has become an important tool for the treatment of actinic cheilitis owing to its ease of use and overall safety, tolerability, and cosmetic acceptability. Herein the use of erbium laser resurfacing is described for three actinic cheilitis presentations for which I find it particularly useful: clinically prominent actinic cheilitis, biopsy-proven actinic cheilitis, and treatment of the entire lip following complete tumor excision of squamous cell carcinoma. All patients were treated with a 2940-nm erbium laser (Sciton Profile Contour Tunable Resurfacing Laser [TRL], Sciton, Inc., Palo Alto, CA). PMID:24196339

  20. Volcanic resurfacing rates and implications for volatiles on Io

    NASA Technical Reports Server (NTRS)

    Johnson, T. V.; Cook, A. F., II; Sagan, C.; Soderblom, L. A.

    1979-01-01

    The rates of volcanic resurfacing on Io are estimated on the basis of two separate observations and the implications of these rates for the volatile history of Io and the supply of material to the Jovian torus are discussed. Rates of resurfacing based on the lack of observable impact craters and assuming a Jovian cratering rate similar to those of the moon and Mars are found to be on the order of 0.1 cm/year. Estimated deposition rates of volcanic matter are found to be in general agreement with cratering rate determinations, if large particle deposition, undetected volcanic activity, volcanic flows and gas condensation are taken into account. Escape rates from Io estimated for sulfur, oxygen and sodium, based on their concentrations around Io, indicate that only a fraction of the present volcanic material can escape. Thermal and nonthermal escape mechanisms are suggested to account for the current loss of sulfur and oxygen from Io's upper atmosphere, while sputtering of atoms from the surface by impacting magnetospheric ions is suggested as the mechanism of sodium supply.

  1. The resurfacing controversy for Venus: An overview and a mechanistic perspective

    NASA Technical Reports Server (NTRS)

    Solomon, Sean C.

    1993-01-01

    Two remarkable aspects of the population of impact craters on Venus are that craters at all sizes are indistinguishable from a random population and that most craters have not been significantly modified by tectonic strain or by volcanic flows external to the crater rim, despite evidence from Magellan images that volcanic and tectonic features are widespread on Venus. One interpretation of these observations is that most of the surface dates from the end of a catastrophic global resurfacing event that ceased about 500 My ago, and that a small fraction of craters volcaniclly embayed or modified by deformation indicate that volcanic and tectonic activity subsequent to that time has been at much lower levels. A competing scenario, in which resurfacing occurs episodically in patches a few hundred kilometers in extent and there is a wider spectrum of surface ages, also appears to be consistent with the characteristics of impact craters on Venus. While geological and statistical studies of the crater population on Venus offer some promise for distinguishing between these two hypotheses, consideration of the possible mechanisms of catastrophic episodic resurfacing provides an independent perspective. Potential mechanisms for catastrophic resurfacing of Venus range from geologically sudden convective destabilization of the global lithosphere to strongly time-dependent heat flux and melt generation in the underlying mantle. For most of these mechanisms, resurfacing occurs implicitly or explicitly by volcanism. An alternative hypothesis is that, at least in the geologically recent history of Venus, the primary resurfacing mechanism has been tectonic deformation rather than volcanism. Because the rate of surface strain should be controlled by the temperature-dependent strength of the lower crust, a geologically rapid transition in surface strain rates should be the natural result of planetary cooling. This transition would occur at comparable times for areas of similar

  2. Early outcomes of patella resurfacing in total knee arthroplasty

    PubMed Central

    Clements, Warren J; Miller, Lisa; Whitehouse, Sarah L; Graves, Stephen E; Ryan, Philip

    2010-01-01

    Background Patella resurfacing in total knee arthroplasty is a contentious issue. The literature suggests that resurfacing of the patella is based on surgeon preference, and little is known about the role and timing of resurfacing and how this affects outcomes. Methods We analyzed 134,799 total knee arthroplasties using data from the Australian Orthopaedic Association National Joint Replacement Registry. Hazards ratios (HRs) were used to compare rates of early revision between patella resurfacing at the primary procedure (the resurfacing group, R) and primary arthroplasty without resurfacing (no-resurfacing group, NR). We also analyzed the outcomes of NR that were revised for isolated patella addition. Results At 5 years, the R group showed a lower revision rate than the NR group: cumulative per cent revision (CPR) 3.1% and 4.0%, respectively (HR = 0.75, p < 0.001). Revisions for patellofemoral pain were more common in the NR group (17%) than in the R group (1%), and “patella only” revisions were more common in the NR group (29%) than in the R group (6%). Non-resurfaced knees revised for isolated patella addition had a higher revision rate than patella resurfacing at the primary procedure, with a 4-year CPR of 15% and 2.8%, respectively (HR = 4.1, p < 0.001). Interpretation Rates of early revision of primary total knees were higher when the patella was not resurfaced, and suggest that surgeons may be inclined to resurface later if there is patellofemoral pain. However, 15% of non-resurfaced knees revised for patella addition are re-revised by 4 years. Our results suggest an early beneficial outcome for patella resurfacing at primary arthroplasty based on revision rates up to 5 years. PMID:19968604

  3. Solutions that enable ablative radiotherapy for large liver tumors: Fractionated dose painting, simultaneous integrated protection, motion management, and computed tomography image guidance.

    PubMed

    Crane, Christopher H; Koay, Eugene J

    2016-07-01

    The emergence and success of stereotactic body radiation therapy (SBRT) for the treatment of lung cancer have led to its rapid adoption for liver cancers. SBRT can achieve excellent results for small liver tumors. However, the vast majority of physicians interpret SBRT as meaning doses of radiation (range, 4-20 Gray [Gy]) that may not be ablative but are delivered within about 1 week (ie, in 3-6 fractions). Adherence to this approach has limited the effectiveness of SBRT for large liver tumors (>7 cm) because of the need to reduce doses to meet organ constraints. The prognosis for patients who present with large liver tumors is poor, with a median survival ≤12 months, and most of these patients die from tumor-related liver failure. Herein, the authors present a comprehensive solution to achieve ablative SBRT doses for patients with large liver tumors by using a combination of classic, modern, and novel concepts of radiotherapy: fractionation, dose painting, motion management, image guidance, and simultaneous integrated protection. The authors discuss these concepts in the context of large, inoperable liver tumors and review how this approach can substantially prolong survival for patients, most of whom otherwise have a very poor prognosis and few effective treatment options. Cancer 2016;122:1974-86. © 2016 American Cancer Society. PMID:26950735

  4. Hip resurfacing: history, current status, and future.

    PubMed

    Amstutz, Harlan C; Le Duff, Michel J

    2015-01-01

    Hip resurfacing arthroplasty (HRA) presents several advantages over conventional total hip arthroplasty (THA), including conservation and preservation of bone, reduced risk of dislocation, easy replication of hip biomechanics and easy revision if needed. It is a particularly appealing procedure for young patients. HRA has been performed for over 40 years following the same technological advances as THA. The bearing material used by most designs is metal-on-metal (MoM), which has the best compromise between strength and wear properties. However, MoM HRA has a specific set of possible complications. Aseptic femoral failures were initially the most prevalent cause for revision but progress in patient selection and surgical technique seem to have resolved this problem. Wear-related failures (high metal ion levels and adverse local tissue reactions) are now the main concern, and are essentially associated with poor acetabular component design and orientation, to which MoM is more sensitive than other bearing materials. The concept of functional coverage is key to understanding how MoM bearings are affected by edge wear. Only a 3-D assessment of cup position (e.g., the contact patch to rim distance) provides the necessary information to determine the role of cup positioning in relationship with abnormal bearing wear.The concept of hip resurfacing is more valid today than ever as the age of the patients in need of hip arthroplasty keeps getting lower. The recent publication of several excellent long-term survivorship results suggests that selection of a well-designed resurfacing system and accuracy in the placement of the cup can achieve long-term durability. PMID:26109156

  5. Noninvasive delivery of siRNA and plasmid DNA into skin by fractional ablation: erbium:YAG laser versus CO₂ laser.

    PubMed

    Lee, Woan-Ruoh; Shen, Shing-Chuan; Chen, Wei-Yu; Aljuffali, Ibrahim A; Suen, Shih-Yun; Fang, Jia-You

    2014-04-01

    The present study was conducted to evaluate the impacts of fractional erbium (Er):YAG and CO2 lasers on skin permeation of small interfering (si)RNA and plasmid (p)DNA vectors. In vitro skin delivery was determined with a Franz diffusion cell. In vivo absorption was investigated by observing fluorescence and confocal microscopic imaging. Fractional laser-mediated ablation of the skin resulted in significant enhancement of dextran and siRNA penetration. Respective fluxes of dextran (10 kDa) and siRNA, which had similar molecular size, with Er:YAG laser irradiation at 5 J/cm(2) were 56- and 11-fold superior to that of intact skin. The respective permeation extents of dextran and siRNA by the CO2 laser at 4 mJ/400 spots were 42- and 12-fold greater than that of untreated skin. Fluorescence and confocal images showed increased fluorescence intensities and penetration depths of siRNA and pDNA delivery. According to an examination of the follicular permeant amount and fluorescence microscopy, hair follicles were important deposition areas for fractional laser-assisted delivery, with the Er:YAG modality revealing higher follicular siRNA selectivity than the CO2 modality. This is the first report of siRNA and pDNA penetrating the skin with a sufficient amount and depth with the assistance of fractional lasers. PMID:23962771

  6. Liquid water and active resurfacing on Europa

    NASA Technical Reports Server (NTRS)

    Squyres, S. W.; Reynolds, R. T.; Cassen, P. M.; Peale, S. J.

    1983-01-01

    Arguments for recent resurfacing of Europa by H2O from a liquid layer are presented, based on new interpretations of recent spacecraft and earth-based observations and revised theoretical calculations. The heat flow in the core and shell due to tidal forces is discussed, and considerations of viscosity and convection in the interior are found to imply water retention in the outer 60 km or so of the silicates, forming a layer of water/ice many tens of km thick. The outer ice crust is considered to be too thin to support heat transport rates sufficient to freeze the underlying water. Observational evidence for the calculations would consist of an insulating layer of frosts derived from water boiling up between cracks in the surface crust. Evidence for the existence of such a frost layer, including the photometric function of Europa and the deposits of sulfur on the trailing hemisphere, is discussed.

  7. Plasma skin resurfacing: personal experience and long-term results.

    PubMed

    Bentkover, Stuart H

    2012-05-01

    This article presents a comprehensive clinical approach to plasma resurfacing for skin regeneration. Plasma technology, preoperative protocols, resurfacing technique, postoperative care, clinical outcomes, evidence-based results, and appropriate candidates for this procedure are discussed. Specific penetration depth and specific laser energy measurements are provided. Nitrogen plasma skin regeneration is a skin-resurfacing technique that offers excellent improvement of mild to moderate skin wrinkles and overall skin rejuvenation. It also provides excellent improvement in uniformity of skin color and texture in patients with hyperpigmentation with Fitzpatrick skin types 1 through 4. PMID:22537783

  8. Optimal acetabular orientation for hip resurfacing.

    PubMed

    Grammatopoulos, G; Pandit, H; Glyn-Jones, S; McLardy-Smith, P; Gundle, R; Whitwell, D; Gill, H S; Murray, D W

    2010-08-01

    Pseudotumours are a rare complication of hip resurfacing. They are thought to be a response to metal debris which may be caused by edge loading due to poor orientation of the acetabular component. Our aim was to determine the optimal acetabular orientation to minimise the risk of pseudotumour formation. We matched 31 hip resurfacings revised for pseudotumour formation with 58 controls who had a satisfactory outcome from this procedure. The radiographic inclination and anteversion angles of the acetabular component were measured on anteroposterior radiographs of the pelvis using Einzel-Bild-Roentgen-Analyse software. The mean inclination angle (47 degrees, 10 degrees to 81 degrees) and anteversion angle (14 degrees, 4 degrees to 34 degrees) of the pseudotumour cases were the same (p = 0.8, p = 0.2) as the controls, 46 degrees (29 degrees to 60 degrees) and 16 degrees (4 degrees to 30 degrees) respectively, but the variation was greater. Assuming an accuracy of implantation of +/- 10 degrees about a target position, the optimal radiographic position was found to be approximately 45 degrees of inclination and 20 degrees of anteversion. The incidence of pseudotumours inside the zone was four times lower (p = 0.007) than outside the zone. In order to minimise the risk of pseudotumour formation we recommend that surgeons implant the acetabular component at an inclination of 45 degrees (+/- 10) and anteversion of 20 degrees (+/- 10) on post-operative radiographs. Because of differences between the radiographic and the operative angles, this may be best achieved by aiming for an inclination of 40 degrees and an anteversion of 25 degrees. PMID:20675749

  9. Granular convection and its application to asteroidal resurfacing timescale

    NASA Astrophysics Data System (ADS)

    Yamada, Tomoya; Ando, Kosuke; Morota, Tomokatsu; Katsuragi, Hiroaki

    2016-04-01

    A model for the asteroid resurfacing resulting from regolith convection is built to estimate its timescale. The regolith convection by impact-induced global seismic shaking could be a possible reason for regolith migration and resultant segregated terrain which were found on the asteroids Itokawa [1]. Some recent studies [2, 3] experimentally investigated the convective velocity of the vibrated granular bed to discuss the feasibility of regolith convection under the microgravity condition such as small asteroids. These studies found that the granular convective velocity is almost proportional to the gravitational acceleration [2, 3]. Namely, the granular (regolith) convective velocity would be very low under the microgravity condition. Therefore, the timescale of resurfacing by regolith convection would become very long. In order to examine the feasibility of the resurfacing by regolith convection on asteroids, its timescale have to be compared with the surface age or the lifetime of asteroids. In this study, we aim at developing a model of asteroid resurfacing process induced by regolith convection. The model allows us to estimate the resurfacing timescale for various-sized asteroids covered with regolith. In the model, regolith convection is driven by the impact-induced global seismic shaking. The model consists of three phases, (i) Impact phase: An impactor intermittently collides with a target asteroid [4], (ii) Vibration phase: The collision results in a global seismic shaking [5], (iii) Convection phase: The global seismic shaking induces the regolith convection on the asteroid [3]. For the feasibility assessment of the resurfacing process driven by regolith convection, we estimate the regolith-convection-based resurfacing timescale T as a function of the size of a target asteroid Da. According to the estimated result, the resurfacing time scale is 40 Myr for the Itokawa-sized asteroid, and this value is shorter than the mean collisional lifetime of Itokawa

  10. Biologic resurfacing of the patella: current status.

    PubMed

    Scapinelli, Raphaele; Aglietti, Paolo; Baldovin, Marino; Giron, Francesco; Teitge, Robert

    2002-07-01

    The techniques of biologic resurfacing of the patella, like other joint surfaces, are still evolving. Currently none of them is free from criticism. In this regard it is our hope that progress in the basic science will offer in the near future new and more optimistic therapeutic possibilities (i.e., the restoration of a reparative cartilage that is structurally and functionally comparable to the native one). The greater expectancies come perhaps from the present experimental investigations about the combined use of tissue-engineered implants embedded with staminal cells and growth factors. Many problems remain to be solved, however, before reliable applicability in humans. From a general point of view, stem cells obtained from various sources (e.g., adult bone marrow, umbilical cord) offer the same finalities as the embryonic stem cells, without the ethical obstacles related to the latter. Therefore, it may be that restoration of part or all of the articular surface of a joint will be possible by way of these mesenchymal progenitors that have the ability to differentiate into the chondrogenic and osteogenic lines, which is required for the restoration of the various layers of a normal articular cartilage and subchondral bone. PMID:12365242

  11. Cement applicator use for hip resurfacing arthroplasty.

    PubMed

    Jaeger, Sebastian; Rieger, Johannes S; Obermeyer, Beate; Klotz, Matthias C; Kretzer, J Philippe; Bitsch, Rudi G

    2015-05-01

    We compared the manufacturer recommended cementing technique for a femoral hip resurfacing implant (BHR, S&N) to a newly designed cement applicator on 20 porous carbon foam specimens. Substantial design changes and improvements of the cement applicator were necessary: The diameter and number of the cement escaping holes at the top of the applicator were optimized for medium viscosity cement. It was necessary to add four separate air inlet holes with large diameters. The inner shape of the applicator had to be adapted to the BHR design with a circular extending chamfer in the proximal region, a parallel inner wall and a second chamfer distally. The interface temperatures showed no risk for heat necrosis using both techniques. The cement penetration depth was more uniform and significantly reduced for the applicator cementing technique (4.34 ± 1.42 mm, 6.42 ± 0.43 mm, p = 0.001). The cement-applicator showed no cement defects compared to a large defect length (0.0 ± 0.0 mm, 10.36 ± 1.10 mm, p < 0.001) with the manufacturer recommended cementing technique. The cement applicator technique appears to be effective for a homogenous cement distribution without cement defects and safe with a lower risk of polar over-penetration. PMID:25772262

  12. Fire hazards and CO2 laser resurfacing.

    PubMed

    Wald, D; Michelow, B J; Guyuron, B; Gibb, A A

    1998-01-01

    The purpose of this study was to investigate the fire risk of laser resurfacing in the presence of supplemental oxygen. This study aims at defining safety parameters of variables such as laser energy level, oxygen flow rate, and "oxygen to laser target distance" when oxygen is delivered through a nasal cannula or nasopharyngeal tube. The typical operating room environment was simulated in the laboratory using the Yucatan minipig animal model. The energy source was a Coherent Ultrapulse CO2 laser. It was found that combustion did not occur at laser settings of 500 mJ, 50 W, 100 kHz, and a density of 5, used in conjunction with an oxygen flow rate of 6 liter/minute with the target area as close as 0.5 cm to the oxygen delivery. A total of 400 computer pattern generator treatments were delivered using this energy setting without observation of any combustion (p < 0.001). This provides evidence that while using even somewhat high laser settings and oxygen flow rate, laser induced fires can be avoided. We conclude that use of the laser in the presence of oxygen is safe, provided the target area is free of combustible fuels. Despite this assurance, laser mishaps are serious because they lead to both morbidity and mortality. It is our recommendation that close attention be constantly paid to all details, thus reducing the hazard potential of laser energy on local factors in an oxygen-rich environment. PMID:9427936

  13. Carbon dioxide laser resurfacing with fast recovery.

    PubMed

    Chajchir, Abel; Benzaquen, Iliana

    2005-01-01

    ABTRACT: Long sun exposure, in addition to ozone layer damage, produces structural damase to the normal skin. Injury to the dermal collagen and elastic fiber results in facial wrinkles. Photodamage to the skin is one of the most common sources of concern for patients visiting the plastic surgeon or dermatologist. Over the years, many alternative solutions have been developed. CO2 laser treatment is one of the alternatives bringing unique benefits and satisfactory results for both patient and surgeons. However, the initial problems of emotional discomfort, prolonged postoperative recovery and delayed return to normal activities have made patients reluctant to accept this method. This article discusses single-pass CO2 laser resurfacing with lower energy. Also, it proposes a technique that does not use wet gauze to remove the surface of the skin. This technique is applied in combination with an intensive skin care treatment. Different authors propose a single pass of CO2 laser with excellent results. With the reported method, identical long-lasting benefits are achieved, but the post-operative time is shorter. PMID:15803351

  14. Hip resurfacing: a large, US single-surgeon series.

    PubMed

    Brooks, P J

    2016-01-01

    Hip resurfacing has been proposed as an alternative to traditional total hip arthroplasty in young, active patients. Much has been learned following the introduction of metal-on-metal resurfacing devices in the 1990s. The triad of a well-designed device, implanted accurately, in the correct patient has never been more critical than with these implants. Following Food and Drug Administration approval in 2006, we studied the safety and effectiveness of one hip resurfacing device (Birmingham Hip Resurfacing) at our hospital in a large, single-surgeon series. We report our early to mid-term results in 1333 cases followed for a mean of 4.3 years (2 to 5.7) using a prospective, observational registry. The mean patient age was 53.1 years (12 to 84); 70% were male and 91% had osteoarthritis. Complications were few, including no dislocations, no femoral component loosening, two femoral neck fractures (0.15%), one socket loosening (0.08%), three deep infections (0.23%), and three cases of metallosis (0.23%). There were no destructive pseudotumours. Overall survivorship at up to 5.7 years was 99.2%. Aseptic survivorship in males under the age of 50 was 100%. We believe this is the largest United States series of a single surgeon using a single resurfacing system. PMID:26733633

  15. Metal-on-Metal Hip Resurfacing Arthroplasty

    PubMed Central

    Sehatzadeh, S; Kaulback, K; Levin, L

    2012-01-01

    Background Metal-on-metal (MOM) hip resurfacing arthroplasty (HRA) is in clinical use as an appropriate alternative to total hip arthroplasty in young patients. In this technique, a metal cap is placed on the femoral head to cover the damaged surface of the bone and a metal cup is placed in the acetabulum. Objectives The primary objective of this analysis was to compare the revision rates of MOM HRA using different implants with the benchmark set by the National Institute of Clinical Excellence (NICE). The secondary objective of this analysis was to review the literature regarding adverse biological effects associated with implant material. Review Methods A literature search was performed on February 13, 2012, to identify studies published from January 1, 2009, to February 13, 2012. Results The revision rates for MOM HRA using 6 different implants were reviewed. The revision rates for MOM HRA with 3 implants met the NICE criteria, i.e., a revision rate of 10% or less at 10 years. Two implants had short-term follow-ups and MOM HRA with one of the implants failed to meet the NICE criteria. Adverse tissue reactions resulting in failure of the implants have been reported by several studies. With a better understanding of the factors that influence the wear rate of the implants, adverse tissue reactions and subsequent implant failure can be minimized. Many authors have suggested that patient selection and surgical technique affect the wear rate and the risk of tissue reactions. The biological effects of high metal ion levels in the blood and urine of patients with MOM HRA implants are not known. Studies have shown an increase in chromosomal aberrations in patients with MOM articulations, but the clinical implications and long-term consequences of this increase are still unknown. Epidemiological studies have shown that patients with MOM HRA implants did not have an overall increase in mortality or risk of cancer. There is insufficient clinical data to confirm the

  16. Activities: Understanding Division of Fractions.

    ERIC Educational Resources Information Center

    Bezuk, Nadine S.; Armstrong, Barbara E.

    1993-01-01

    Presents a series of five activities that introduce division of fractions through real-world situations. Discusses problems related to resurfacing a highway, painting dividing stripes on a highway, covering one area A with another area B, looking for patterns, and maximizing the result of a division problem. Includes reproducible worksheets. (MDH)

  17. Resurfacing of the Metatarsal Head to Treat Advanced Hallux Rigidus.

    PubMed

    Kline, Alex J; Hasselman, Carl T

    2015-09-01

    Advanced stages of hallux rigidus are usually treated with various arthroplasties or arthrodesis. Recent results with resurfacing of the metatarsal head have shown promising results and outcomes similar or superior to those of arthrodesis. In this article, the authors show their preoperative decision making, surgical techniques, postoperative management, results, and a comparative literature review to identify metatarsal head resurfacing as an acceptable technique for the treatment of advanced hallux rigidus in active patients. Key points in this article are adequate soft tissue release, immediate rigid fixation of the components, and appropriate alignment of the components. PMID:26320559

  18. 21 CFR 888.3590 - Knee joint tibial (hemi-knee) metallic resurfacing uncemented prosthesis.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Knee joint tibial (hemi-knee) metallic resurfacing... Knee joint tibial (hemi-knee) metallic resurfacing uncemented prosthesis. (a) Identification. A knee joint tibial (hemi-knee) metallic resurfacing uncemented prosthesis is a device intended to be...

  19. 21 CFR 888.3590 - Knee joint tibial (hemi-knee) metallic resurfacing uncemented prosthesis.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Knee joint tibial (hemi-knee) metallic resurfacing... Knee joint tibial (hemi-knee) metallic resurfacing uncemented prosthesis. (a) Identification. A knee joint tibial (hemi-knee) metallic resurfacing uncemented prosthesis is a device intended to be...

  20. 21 CFR 888.3590 - Knee joint tibial (hemi-knee) metallic resurfacing uncemented prosthesis.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Knee joint tibial (hemi-knee) metallic resurfacing... Knee joint tibial (hemi-knee) metallic resurfacing uncemented prosthesis. (a) Identification. A knee joint tibial (hemi-knee) metallic resurfacing uncemented prosthesis is a device intended to be...

  1. 21 CFR 888.3590 - Knee joint tibial (hemi-knee) metallic resurfacing uncemented prosthesis.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Knee joint tibial (hemi-knee) metallic resurfacing... Knee joint tibial (hemi-knee) metallic resurfacing uncemented prosthesis. (a) Identification. A knee joint tibial (hemi-knee) metallic resurfacing uncemented prosthesis is a device intended to be...

  2. 21 CFR 888.3590 - Knee joint tibial (hemi-knee) metallic resurfacing uncemented prosthesis.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Knee joint tibial (hemi-knee) metallic resurfacing... Knee joint tibial (hemi-knee) metallic resurfacing uncemented prosthesis. (a) Identification. A knee joint tibial (hemi-knee) metallic resurfacing uncemented prosthesis is a device intended to be...

  3. Failure of total knee arthroplasty with or without patella resurfacing

    PubMed Central

    2011-01-01

    Background and purpose Patella resurfacing during primary total knee arthroplasty (TKA) is disputed and new prosthesis designs have been introduced without documentation of their survival. We assessed the impact on prosthesis survival of patella resurfacing and of prosthesis brand, based on data from the Norwegian Arthroplasty Register. Patients and methods 5 prosthesis brands in common use with and without patella resurfacing from 1994 through 2009 were included n = 11,887. The median follow-up times were 9 years for patella-resurfaced implants and 7 years for implants without patella resurfacing. For comparison of prosthesis brands, also brands in common use with only one of the two treatment options were included in the study population (n = 25,590). Cox regression analyses were performed with different reasons for revision as endpoints with adjustment for potential confounders. Results We observed a reduced overall risk of revision for patella resurfaced (PR) TKAs, but the statistical significance was borderline (RR = 0.84, p = 0.05). At 15 years, 92% of PR and 91% of patella non resurfaced (NR) prostheses were still unrevised. However, PR implants had a lower risk of revision due to pain alone (RR = 0.1, p < 0.001), but a higher risk of revision due to loosening of the tibial component (RR = 1.4, p = 0.03) and due to a defective polyethylene insert (RR = 3.2, p < 0.001). At 10 years, the survival for the reference NR brand AGC Universal was 93%. The NR brands Genesis I, Duracon, and Tricon (RR = 1.4–1.7) performed statistically significantly worse than NR AGC Universal, while the NR prostheses e.motion, Profix, and AGC Anatomic (RR = 0.1–0.7), and the PR prostheses NexGen and AGC Universal (RR = 0.4–0.5) performed statistically significantly better. LCS, NexGen, LCS Complete (all NR), and Tricon, Genesis I, LCS, and Kinemax (all PR) showed no differences in this respect from the reference brand. A lower risk of revision (crude) was found for TKAs

  4. Primary total hip replacement versus hip resurfacing - hospital considerations.

    PubMed

    Ward, William G; Carter, Christina J; Barone, Marisa; Jinnah, Riyaz

    2011-01-01

    Multiple factors regarding surgical procedures and patient selection affect hospital staffing needs as well as hospital revenues. In order to better understand the potential impact on hospitals that hip arthroplasty device selection (standard total hip arthroplasty vs. resurfacing) creates, a review of all primary hip arthroplasties performed at one institution was designed to identify factors that impacted hospital staffing needs and revenue generation. All primary hip arthroplasties undertaken over three fiscal years (2008 to 2010) were reviewed, utilizing only hospital business office data and medical records data that had been previously extracted prior for billing purposes. Analysis confirmed differing demographics for two hip arthroplasty populations, with the resurfacing patients (compared to the conventional total hip arthroplasty population) consisting of younger patients (mean age, 50 vs. 61 years), who were more often male (75% vs. 45%), were more likely to have osteoarthritis as their primary diagnosis (83 vs. 67%) and were more often covered by managed care or commercial insurance (83 vs. 34%). They also had shorter hospital stays (mean length of stay, 2.3 vs. 4.1 days) and consequently provided a more favorable financial revenue stream to the hospital on a per patient basis. Several trends appeared during the study periods. There was a steady increase in all procedures in all groups except for the resurfacings, which decreased 26% in males and 53% in females between 2009 and 2010. Differences were observed in the demographics of patients presenting for resurfacing, compared to those presenting for conventional total hip arthroplasty. In addition to the revenue stream considerations, institutions undertaking a resurfacing program must commit the resources and planning in order to rehabilitate these patients more expeditiously than is usually required with conventional hip arthroplasty patients. PMID:22035493

  5. Hip resurfacing in a district general hospital: 6-year clinical results using the ReCap hip resurfacing system

    PubMed Central

    2012-01-01

    Background The purpose of our study was to prospectively report the clinical results of 280 consecutive hips (240 patients) who received a ReCap Hip Resurfacing System implant (Biomet Inc., Warsaw, USA) in a single district general hospital. Literature reports a large variation in clinical results between different resurfacing designs and published results using this particular design are scarce. Methods Mean follow up was 3.3 years (1.0 to 6.3) and four patients were lost to follow-up. All patients were diagnosed with end-stage hip osteoarthritis, their mean age was 54 years and 76.4% of all patients were male. Results There were 16 revisions and four patients reported a Harris Hip Score <70 points at their latest follow up. There were no pending revisions. Kaplan-Meier implant survival probability, with revision for any reason as endpoint, was 93.5% at six years follow-up (95%-CI: 88.8-95.3). There were no revisions for Adverse Reactions to Metal Debris (ARMD) and no indications of ARMD in symptomatic non-revised patients, although diagnostics were limited to ultrasound scans. Conclusions This independent series confirms that hip resurfacing is a demanding procedure, and that implant survival of the ReCap hip resurfacing system is on a critical level in our series. In non-revised patients, reported outcomes are generally excellent. Trial registration ClinicalTrials.gov Identifier: NCT00603395 PMID:23234268

  6. Similar patient-reported outcomes and performance after total knee arthroplasty with or without patellar resurfacing.

    PubMed

    Ali, Abdulemir; Lindstrand, Anders; Nilsdotter, Anna; Sundberg, Martin

    2016-06-01

    Background and purpose - Knee pain after total knee arthroplasty (TKA) is not uncommon. Patellar retention in TKA is one cause of postoperative knee pain, and may lead to secondary addition of a patellar component. Patellar resurfacing in TKA is controversial. Its use ranges from 2% to 90% worldwide. In this randomized study, we compared the outcome after patellar resurfacing and after no resurfacing. Patients and methods - We performed a prospective, randomized study of 74 patients with primary osteoarthritis who underwent a Triathlon CR TKA. The patients were randomized to either patellar resurfacing or no resurfacing. They filled out the VAS pain score and KOOS questionnaires preoperatively, and VAS pain, KOOS, and patient satisfaction 3, 12, and 72 months postoperatively. Physical performance tests were performed preoperatively and 3 months postoperatively. Results - We found similar scores for VAS pain, patient satisfaction, and KOOS 5 subscales at 3, 12, and 72 months postoperatively in the 2 groups. Physical performance tests 3 months postoperatively were also similar in the 2 groups. No secondary resurfacing was performed in the group with no resurfacing during the first 72 months Interpretation - Patellar resurfacing in primary Triathlon CR TKA is of no advantage regarding pain, physical performance, KOOS 5 subscales, or patient satisfaction compared to no resurfacing. None of the patients were reoperated with secondary addition of a patellar component within 6 years. According to these results, routine patellar resurfacing in primary Triathlon TKA appears to be unnecessary. PMID:27212102

  7. Similar patient-reported outcomes and performance after total knee arthroplasty with or without patellar resurfacing

    PubMed Central

    Ali, Abdulemir; Lindstrand, Anders; Nilsdotter, Anna; Sundberg, Martin

    2016-01-01

    Background and purpose Knee pain after total knee arthroplasty (TKA) is not uncommon. Patellar retention in TKA is one cause of postoperative knee pain, and may lead to secondary addition of a patellar component. Patellar resurfacing in TKA is controversial. Its use ranges from 2% to 90% worldwide. In this randomized study, we compared the outcome after patellar resurfacing and after no resurfacing. Patients and methods We performed a prospective, randomized study of 74 patients with primary osteoarthritis who underwent a Triathlon CR TKA. The patients were randomized to either patellar resurfacing or no resurfacing. They filled out the VAS pain score and KOOS questionnaires preoperatively, and VAS pain, KOOS, and patient satisfaction 3, 12, and 72 months postoperatively. Physical performance tests were performed preoperatively and 3 months postoperatively. Results We found similar scores for VAS pain, patient satisfaction, and KOOS 5 subscales at 3, 12, and 72 months postoperatively in the 2 groups. Physical performance tests 3 months postoperatively were also similar in the 2 groups. No secondary resurfacing was performed in the group with no resurfacing during the first 72 months Interpretation Patellar resurfacing in primary Triathlon CR TKA is of no advantage regarding pain, physical performance, KOOS 5 subscales, or patient satisfaction compared to no resurfacing. None of the patients were reoperated with secondary addition of a patellar component within 6 years. According to these results, routine patellar resurfacing in primary Triathlon TKA appears to be unnecessary. PMID:27212102

  8. Laserpeel: a peeling concept revolution with laser resurfacing protocols

    NASA Astrophysics Data System (ADS)

    Tenenbaum, Alain

    2000-06-01

    The author who is inventor of EasyPeel then Laserpeel wants to introduce new ways to choose the right indications for patients asking for cosmetic surgery. A lifting is as if you take a shirt and want to reduce its size cutting it. A resurfacing is as if you put a shirt and want to iron it. A peeling was as if you changed the color and grain of the shirt. Laserpeel is as if you iron the shirt treated with amidon, transform the second hand shirt as new, up to date on with glance effect sand give it then a stretching disco new wave effect. So, indications of facial lifting decrease at the same speed at the increase of indications of 'LASERPEEL'. Laser CO2 resurfacing should reborn because the post redness appearance decreases in intensity and duration due to LASERPEEL. LASERPEEL should be considered too as a preventive therapy coupled with preventive treatment resulting from longevity tests.

  9. Thermal injuries as a result of CO2 laser resurfacing.

    PubMed

    Grossman, A R; Majidian, A M; Grossman, P H

    1998-09-01

    CO2 laser resurfacing of the face for fine wrinkles has gained great popularity over a short period of time. The use of the CO2 laser has proven to be effective in reducing or eliminating fine wrinkles. This tool in the surgeon's armamentarium has been added to those of dermabrasion and chemical peel. The theoretical advantage of the use of the CO2 laser for resurfacing has been better accuracy and reportedly more control of the depth of penetration. The use of the CO2 laser has been welcomed by many cosmetic surgeons. Until now, there have been few reported cases of complications with the use of the CO2 laser. To many, this would sound too good to be true; unfortunately, that is the case. The CO2 laser is a high-energy machine that can indeed cause thermal injury. This thermal injury can result in deep burns to the skin and hypertrophic scarring. We feel this is more common than is currently being reported, and we share our experience as a burn and wound care referral service. During an 18-month period, 20 consecutive patients were referred to our practice who had received injuries from the CO2 laser resurfacing laser. We present here in this review a summary of those injuries. The CO2 resurfacing laser is a very effective tool for the treatment of fine wrinkles, but it is not without the potential for serious complications. We urge caution with the use of the laser and prompt recognition and treatment of thermal injury to the skin. PMID:9734452

  10. Resurfacing Damaged Articular Cartilage to Restore Compressive Properties

    PubMed Central

    Grenier, Stephanie; Donnelly, Patrick E.; Gittens, Jamila; Torzilli, Peter A.

    2014-01-01

    Surface damage to articular cartilage is recognized as the initial underlying process causing the loss of mechanical function in early-stage osteoarthritis. In this study, we developed structure-modifying treatments to potentially prevent, stabilize or reverse the loss in mechanical function. Various polymers (chondroitin sulfate, carboxymethylcellulose, sodium hyaluronate) and photoinitiators (riboflavin, irgacure 2959) were applied to the surface of collagenase-degraded cartilage and crosslinked in situ using UV light irradiation. While matrix permeability and deformation significantly increased following collagenase-induced degradation of the superficial zone, resurfacing using tyramine-substituted sodium hyaluronate and riboflavin decreased both values to a level comparable to that of intact cartilage. Repetitive loading of resurfaced cartilage showed minimal variation in the mechanical response over a 7 day period. Cartilage resurfaced using a low concentration of riboflavin had viable cells in all zones while a higher concentration resulted in a thin layer of cell death in the uppermost superficial zone. Our approach to repair surface damage initiates a new therapeutic advance in the treatment of injured articular cartilage with potential benefits that include enhanced mechanical properties, reduced susceptibility to enzymatic degradation and reduced adhesion of macrophages. PMID:25468298

  11. Monte Carlo computer simulations of Venus equilibrium and global resurfacing models

    NASA Technical Reports Server (NTRS)

    Dawson, D. D.; Strom, R. G.; Schaber, G. G.

    1992-01-01

    Two models have been proposed for the resurfacing history of Venus: (1) equilibrium resurfacing and (2) global resurfacing. The equilibrium model consists of two cases: in case 1, areas less than or equal to 0.03 percent of the planet are spatially randomly resurfaced at intervals of less than or greater than 150,000 yr to produce the observed spatially random distribution of impact craters and average surface age of about 500 m.y.; and in case 2, areas greater than or equal to 10 percent of the planet are resurfaced at intervals of greater than or equal to 50 m.y. The global resurfacing model proposes that the entire planet was resurfaced about 500 m.y. ago, destroying the preexisting crater population and followed by significantly reduced volcanism and tectonism. The present crater population has accumulated since then with only 4 percent of the observed craters having been embayed by more recent lavas. To test the equilibrium resurfacing model we have run several Monte Carlo computer simulations for the two proposed cases. It is shown that the equilibrium resurfacing model is not a valid model for an explanation of the observed crater population characteristics or Venus' resurfacing history. The global resurfacing model is the most likely explanation for the characteristics of Venus' cratering record. The amount of resurfacing since that event, some 500 m.y. ago, can be estimated by a different type of Monte Carolo simulation. To date, our initial simulation has only considered the easiest case to implement. In this case, the volcanic events are randomly distributed across the entire planet and, therefore, contrary to observation, the flooded craters are also randomly distributed across the planet.

  12. Ablative system

    NASA Technical Reports Server (NTRS)

    Gray, V. H. (Inventor)

    1973-01-01

    A carrier liquid containing ablative material bodies is connected to a plenum chamber wall with openings to a high temperature environment. The liquid and bodies pass through the openings of the wall to form a self replacing ablative surface. The wall is composed of honeycomb layers, spheres containing ablative whiskers or wads, and a hardening catalyst for the carrier liquid. The wall also has woven wicks of ablative material fibers that extend through the wall openings and into plenum chamber which contains the liquid.

  13. Current indications for hip resurfacing arthroplasty in 2016.

    PubMed

    Sershon, Robert; Balkissoon, Rishi; Valle, Craig J Della

    2016-03-01

    Hip resurfacing arthroplasty (HRA) is an alternative to conventional, stemmed total hip arthroplasty (THA). The best reported results are young, active patients with good bone stock and a diagnosis of osteoarthritis. Since the 1990s, metal-on-metal (MoM) HRA has achieved excellent outcomes when used in the appropriate patient population. Concerns regarding the metal-on-metal bearing surface including adverse local tissue reaction (ALTR) to metal debris have recently lead to a decline in the use of this construct. The current paper aims to provide an updated review on HRA, including a critical review of the most recent literature on HRA. PMID:26830851

  14. Photoaging and the clinical utility of fractional laser

    PubMed Central

    Borges, Juliano; Manela-Azulay, Mônica; Cuzzi, Tullia

    2016-01-01

    The description of atomic structure by Niels Bohr set the basis for the emergence of quantum physics. Based on these fundamentals, Einstein published in 1917 a paper on the amplification of energy by Stimulated Emission of Radiation as part of his quantum theories. In 1955, Townes and Gordon turned Einstein’s theories into practice, creating a coherent and amplified microwave device using ammonia gas in an optical medium. But it was at the beginning of the 1980s, that Anderson and Parrish published an article about the selective photothermolysis model which revolutionized clinical practice. The use of laser in photoaging began with CO2 (10,600 nm). In 1989, it was first used for resurfacing of a face with prominent photoaging. Ablative lasers have therefore had great popularity in the 1980s and 1990s, but prolonged postoperative time and significant risk of side effects have lowered the acceptance by patients. In 2004, the description of the fractionated radiation for the treatment of photoaging, by Mainstein, represented a great event. The stimulation of collagen occurred through fractional laser beams, which would reach the selected area while saving islands of sound skin. These islands accelerated the process of cicatrization of the treated tissue and shortened the postprocedure time. Furthermore, the fractionated radiation presented a smaller range of side effects, increasing the safety of the procedure. As mentioned earlier, as fractional lasers incise on the skin, they leave islands of healthy skin that accelerate recovery, while generating necrosis columns. Such necrosis columns remove damaged extracellular matrix material, allowing resettlement of fibroblasts. Such resettled fibroblasts, under the influence of a new tensile strength, restart to produce structures for extracellular matrix, such as collagen, elastin, and proteoglycans, in a more physiological way. Fractional lasers are considered by many dermatologists as the best choice in laser therapy

  15. Photoaging and the clinical utility of fractional laser.

    PubMed

    Borges, Juliano; Manela-Azulay, Mônica; Cuzzi, Tullia

    2016-01-01

    The description of atomic structure by Niels Bohr set the basis for the emergence of quantum physics. Based on these fundamentals, Einstein published in 1917 a paper on the amplification of energy by Stimulated Emission of Radiation as part of his quantum theories. In 1955, Townes and Gordon turned Einstein's theories into practice, creating a coherent and amplified microwave device using ammonia gas in an optical medium. But it was at the beginning of the 1980s, that Anderson and Parrish published an article about the selective photothermolysis model which revolutionized clinical practice. The use of laser in photoaging began with CO2 (10,600 nm). In 1989, it was first used for resurfacing of a face with prominent photoaging. Ablative lasers have therefore had great popularity in the 1980s and 1990s, but prolonged postoperative time and significant risk of side effects have lowered the acceptance by patients. In 2004, the description of the fractionated radiation for the treatment of photoaging, by Mainstein, represented a great event. The stimulation of collagen occurred through fractional laser beams, which would reach the selected area while saving islands of sound skin. These islands accelerated the process of cicatrization of the treated tissue and shortened the postprocedure time. Furthermore, the fractionated radiation presented a smaller range of side effects, increasing the safety of the procedure. As mentioned earlier, as fractional lasers incise on the skin, they leave islands of healthy skin that accelerate recovery, while generating necrosis columns. Such necrosis columns remove damaged extracellular matrix material, allowing resettlement of fibroblasts. Such resettled fibroblasts, under the influence of a new tensile strength, restart to produce structures for extracellular matrix, such as collagen, elastin, and proteoglycans, in a more physiological way. Fractional lasers are considered by many dermatologists as the best choice in laser therapy for

  16. Current Hot Potatoes in Atrial Fibrillation Ablation

    PubMed Central

    Roten, Laurent; Derval, Nicolas; Pascale, Patrizio; Scherr, Daniel; Komatsu, Yuki; Shah, Ashok; Ramoul, Khaled; Denis, Arnaud; Sacher, Frédéric; Hocini, Mélèze; Haïssaguerre, Michel; Jaïs, Pierre

    2012-01-01

    Atrial fibrillation (AF) ablation has evolved to the treatment of choice for patients with drug-resistant and symptomatic AF. Pulmonary vein isolation at the ostial or antral level usually is sufficient for treatment of true paroxysmal AF. For persistent AF ablation, drivers and perpetuators outside of the pulmonary veins are responsible for AF maintenance and have to be targeted to achieve satisfying arrhythmia-free success rate. Both complex fractionated atrial electrogram (CFAE) ablation and linear ablation are added to pulmonary vein isolation for persistent AF ablation. Nevertheless, ablation failure and necessity of repeat ablations are still frequent, especially after persistent AF ablation. Pulmonary vein reconduction is the main reason for arrhythmia recurrence after paroxysmal and to a lesser extent after persistent AF ablation. Failure of persistent AF ablation mostly is a consequence of inadequate trigger ablation, substrate modification or incompletely ablated or reconducting linear lesions. In this review we will discuss these points responsible for AF recurrence after ablation and review current possibilities on how to overcome these limitations. PMID:22920482

  17. 21 CFR 888.3580 - Knee joint patellar (hemi-knee) metallic resurfacing uncemented prosthesis.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Knee joint patellar (hemi-knee) metallic... § 888.3580 Knee joint patellar (hemi-knee) metallic resurfacing uncemented prosthesis. (a) Identification. A knee joint patellar (hemi-knee) metallic resurfacing uncemented prosthesis is a device made...

  18. 21 CFR 888.3580 - Knee joint patellar (hemi-knee) metallic resurfacing uncemented prosthesis.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Knee joint patellar (hemi-knee) metallic... § 888.3580 Knee joint patellar (hemi-knee) metallic resurfacing uncemented prosthesis. (a) Identification. A knee joint patellar (hemi-knee) metallic resurfacing uncemented prosthesis is a device made...

  19. 21 CFR 888.3580 - Knee joint patellar (hemi-knee) metallic resurfacing uncemented prosthesis.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Knee joint patellar (hemi-knee) metallic... § 888.3580 Knee joint patellar (hemi-knee) metallic resurfacing uncemented prosthesis. (a) Identification. A knee joint patellar (hemi-knee) metallic resurfacing uncemented prosthesis is a device made...

  20. 21 CFR 888.3400 - Hip joint femoral (hemi-hip) metallic resurfacing prosthesis.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Hip joint femoral (hemi-hip) metallic resurfacing... HUMAN SERVICES (CONTINUED) MEDICAL DEVICES ORTHOPEDIC DEVICES Prosthetic Devices § 888.3400 Hip joint femoral (hemi-hip) metallic resurfacing prosthesis. (a) Identification. A hip joint femoral...

  1. 21 CFR 888.3400 - Hip joint femoral (hemi-hip) metallic resurfacing prosthesis.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Hip joint femoral (hemi-hip) metallic resurfacing... HUMAN SERVICES (CONTINUED) MEDICAL DEVICES ORTHOPEDIC DEVICES Prosthetic Devices § 888.3400 Hip joint femoral (hemi-hip) metallic resurfacing prosthesis. (a) Identification. A hip joint femoral...

  2. 21 CFR 888.3400 - Hip joint femoral (hemi-hip) metallic resurfacing prosthesis.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Hip joint femoral (hemi-hip) metallic resurfacing... HUMAN SERVICES (CONTINUED) MEDICAL DEVICES ORTHOPEDIC DEVICES Prosthetic Devices § 888.3400 Hip joint femoral (hemi-hip) metallic resurfacing prosthesis. (a) Identification. A hip joint femoral...

  3. 21 CFR 888.3400 - Hip joint femoral (hemi-hip) metallic resurfacing prosthesis.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Hip joint femoral (hemi-hip) metallic resurfacing... HUMAN SERVICES (CONTINUED) MEDICAL DEVICES ORTHOPEDIC DEVICES Prosthetic Devices § 888.3400 Hip joint femoral (hemi-hip) metallic resurfacing prosthesis. (a) Identification. A hip joint femoral...

  4. 21 CFR 888.3400 - Hip joint femoral (hemi-hip) metallic resurfacing prosthesis.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Hip joint femoral (hemi-hip) metallic resurfacing... HUMAN SERVICES (CONTINUED) MEDICAL DEVICES ORTHOPEDIC DEVICES Prosthetic Devices § 888.3400 Hip joint femoral (hemi-hip) metallic resurfacing prosthesis. (a) Identification. A hip joint femoral...

  5. Thermal measurements of short-duration CO2 laser resurfacing

    NASA Astrophysics Data System (ADS)

    Harris, David M.; Fried, Daniel; Reinisch, Lou; Bell, Thomas; Lyver, Rex

    1997-05-01

    The thermal consequences of a 100 microsecond carbon-dioxide laser used for skin resurfacing were examined with infrared radiometry. Human skin was evaluated in a cosmetic surgery clinic and extirpated rodent skin was measured in a research laboratory. Thermal relaxation following single pulses of in vivo human and ex vivo animal skin were quantitatively similar in the 30 - 1000 msec range. The thermal emission from the area of the irradiated tissue increased monotonically with increasing incident laser fluence. Extremely high peak temperatures during the 100 microsecond pulse are attributed to plume incandescence. Ejecta thermal emission may also contribute to our measurements during the first several msecs. The data are combined into a thermal relaxation model. Given known coefficients, and adjusting tissue absorption to reflect a 50% water content, and thermal conductivity of 2.3 times that of water, the measured (both animal back and human forearm) and calculated values coincide. The high thermal conductance suggests preferential thermal conduction along the protein matrix. The clinical observation of a resurfacing procedure clearly shows thermal overlap and build-up is a result of sequential, adjacent pulses. A decrease of 4 - 6 degrees Celsius in surface temperature at the treatment site that appeared immediately post-Tx and gradually diminished over several days is possibly a sign of dermal convective and/or evaporative cooling.

  6. Endometrial ablation

    MedlinePlus

    ... can be seen on the video screen. Small tools can be used through the scope to remove abnormal growths or tissue for examination. Ablation uses heat, cold, or electricity to destroy the lining of the womb. The ...

  7. Ablation article and method

    NASA Technical Reports Server (NTRS)

    Erickson, W. D.; Sullivan, E. M. (Inventor)

    1973-01-01

    An ablation article, such as a conical heat shield, having an ablating surface is provided with at least one discrete area of at least one seed material, such as aluminum. When subjected to ablation conditions, the seed material is ablated. Radiation emanating from the ablated seed material is detected to analyze ablation effects without disturbing the ablation surface. By providing different seed materials having different radiation characteristics, the ablating effects on various areas of the ablating surface can be analyzed under any prevailing ablation conditions. The ablating article can be provided with means for detecting the radiation characteristics of the ablated seed material to provide a self-contained analysis unit.

  8. Metal-on-Metal Total Hip Resurfacing Arthroplasty

    PubMed Central

    2006-01-01

    Executive Summary Objective The objective of this review was to assess the safety and effectiveness of metal on metal (MOM) hip resurfacing arthroplasty for young patients compared with that of total hip replacement (THR) in the same population. Clinical Need Total hip replacement has proved to be very effective for late middle-aged and elderly patients with severe degenerative diseases of the hips. As indications for THR began to include younger patients and those with a more active life style, the longevity of the implant became a concern. Evidence suggests that these patients experience relatively higher rates of early implant failure and the need for revision. The Swedish hip registry, for example, has demonstrated a survival rate in excess of 80% at 20 years for those aged over 65 years, whereas this figure was 33% by 16 years in those aged under 55 years. Hip resurfacing arthroplasty is a bone-conserving alternative to THR that restores normal joint biomechanics and load transfer. The technique has been used around the world for more than 10 years, specifically in the United Kingdom and other European countries. The Technology Metal-on-metal hip resurfacing arthroplasty is an alternative procedure to conventional THR in younger patients. Hip resurfacing arthroplasty is less invasive than THR and addresses the problem of preserving femoral bone stock at the initial operation. This means that future hip revisions are possible with THR if the initial MOM arthroplasty becomes less effective with time in these younger patients. The procedure involves the removal and replacement of the surface of the femoral head with a hollow metal hemisphere, which fits into a metal acetabular cup. Hip resurfacing arthroplasty is a technically more demanding procedure than is conventional THR. In hip resurfacing, the femoral head is retained, which makes it much more difficult to access the acetabular cup. However, hip resurfacing arthroplasty has several advantages over a

  9. Bipaddled anterolateral thigh perforator flap for simultaneous reconstruction of bilateral buccal defects following oral cancer ablation or release of oral submucous fibrosis

    PubMed Central

    Chen, Wei-Chen; Changchien, Chih-Hsuan; Su, Yu-Min

    2016-01-01

    It is a challenge to simultaneously reconstruct bilateral buccal defects following oral cancer ablation or release of oral submucous fibrosis. In this study, we report two cases where bipaddled anterolateral thigh perforator flaps were used to resurface two separate buccal defects. PMID:27619322

  10. Does patella resurfacing really matter? Pain and function in 972 patients after primary total knee arthroplasty

    PubMed Central

    Espehaug, Birgitte; Havelin, Leif Ivar; Vollset, Stein Emil; Furnes, Ove

    2010-01-01

    Background and purpose Resurfacing of the patella during primary total knee arthroplasty (TKA) is often recommended based on higher revision rates in non-resurfaced knees. As many of these revisions are insertions of a patella component due to pain, and since only patients with a non-resurfaced patella have the option of secondary resurfacing, we do not really know whether these patients have more pain and poorer function. The main purpose of the present paper was therefore to assess pain and function at least 2 years after surgery for unrevised primary non-resurfaced and resurfaced TKA, and secondary among prosthesis brands. Methods Information needed to calculate subscales from the knee injury and osteoarthritis outcome score (KOOS) was collected in a questionnaire given to 972 osteoarthritis patients with intact primary TKAs that had been reported to the Norwegian Arthroplasty Register. Pain and satisfaction on visual analog scales and improvement in EQ-5D index score ΔEQ-5D) were also used as outcomes. Outcomes were measured on a scale from 0 to 100 units (worst to best). To estimate differences in mean scores, we used multiple linear regression with adjustment for possible confounders. Results We did not observe any differences between resurfacing and non-resurfacing in any outcome, with estimated differences of ≤ 1.4 units and p-values of > 0.4. There was, however, a tendency of better results for the NexGen implant as compared to the reference brand AGC for symptoms (difference = 4.9, p = 0.05), pain (VAS) (difference = 8.3, p = 0.004), and satisfaction (VAS) (difference = 7.9, p = 0.02). However, none of these differences reached the stated level of minimal perceptible clinical difference. Interpretation Resurfacing of the patella has no clinical effect on pain and function after TKA. Differences between the brands investigated were small and they were assumed to be of minor importance. PMID:20158405

  11. Confronting Hip Resurfacing and Big Femoral Head Replacement Gait Analysis

    PubMed Central

    Karampinas, Panagiotis K.; Evangelopoulos, Dimitrios S.; Vlamis, John; Nikolopoulos, Konstantinos; Korres, Dimitrios S.

    2014-01-01

    Improved hip kinematics and bone preservation have been reported after resurfacing total hip replacement (THRS). On the other hand, hip kinematics with standard total hip replacement (THR) is optimized with large diameter femoral heads (BFH-THR). The purpose of this study is to evaluate the functional outcomes of THRS and BFH-THR and correlate these results to bone preservation or the large femoral heads. Thirty-one patients were included in the study. Gait speed, postural balance, proprioception and overall performance. Our results demonstrated a non-statistically significant improvement in gait, postural balance and proprioception in the THRS confronting to BFH-THR group. THRS provide identical outcomes to traditional BFH-THR. The THRS choice as bone preserving procedure in younger patients is still to be evaluated. PMID:24744841

  12. Ages of fracturing and resurfacing in the Amenthes region, Mars

    NASA Technical Reports Server (NTRS)

    Maxwell, Ted A.; Mcgill, George E.

    1988-01-01

    An attempt is made to determine whether there is any tectonic evidence in the relatively recent history of the boundary zone that will place contraints on the origin of the Martian dichotomy. It is found that the timing of resurfacing events and structural modification of outlier plateaus and mesas in the Martian eastern hemisphere provides a contraint on the history of tectonic events along the cratered terrain-northern plains boundary. The circumferential grabens surrounding the Isidis basin ceased forming before the final emplacement of ridged plains on the adjacent northern lowlands. The cratered plateau east of the Isidis basin includes two crater populations; stripping of the rims of craters was complete before downfalling of the transition zone between the cratered terrain and the northern plains, and a young population of craters on the plateau records the same age as the ridged plains units north of the boundary.

  13. MOLECULAR RESURFACING OF CARTILAGE WITH PROTEOGLYCAN 4 (PRG4)

    PubMed Central

    Chawla, Kanika; Ham, Hyun Ok; Nguyen, Trung; Messersmith, Phillip B.

    2010-01-01

    Early loss of proteoglycan 4 (PRG4), a lubricating glycoprotein implicated in boundary lubrication, from the cartilage surface has been associated with degeneration of cartilage and early onset of osteoarthritis. Viscosupplementation with hyaluronic acid and other macromolecules has been proposed as a treatment of osteoarthritis, however efficacy of viscosupplementation is variable and may be influenced by the short residence time of lubricant in the knee joint after injection. Recent studies have demonstrated the use of aldehyde (CHO) modified extracellular matrix proteins for targeted adherence to a biological tissue surface. We hypothesized that CHO could be exploited to enhance binding of lubricating proteoglycans to the surface of PRG4 depleted cartilage. The objective of this study was to determine the feasibility of molecular resurfacing of cartilage with aldehyde modified PRG4. PRG4 was chemically functionalized with aldehyde (PRG4-CHO), and aldehyde plus Oregon Green (OG) fluorophore (PRG4-OG-CHO) to allow for differentiation of endogenous and exogenous PRG4. Cartilage disks depleted of native PRG4 were then treated with solutions of PRG4, PRG4-CHO, or PRG4-OG-CHO and then assayed for the presence of PRG4 by immunohistochemistry, ELISA, and fluorescence imaging. Repletion of cartilage surfaces was significantly enhanced with the inclusion of CHO compared to repletion with unmodified PRG4. These findings suggest a generalized approach that may be used for molecular resurfacing of tissue surfaces with PRG4 and other lubricating biomolecules, perhaps leading in the future to a convenient method for overcoming loss of lubrication during the early stages of osteoarthritis. PMID:20338268

  14. Volcanic resurfacing of Io between Galileo and New Horizons Observations

    NASA Astrophysics Data System (ADS)

    Coman, E.; Phillips, C. B.

    2011-12-01

    Io is the most geologically active object in our solar system. Due to its tumultuous volcanism, determining Io's resurfacing rate will allow better characterization of the subsurface structure, thermal state, and history of tidal heating of this small moon. Numerous active volcanic centers were documented during the Galileo mission in the late 1990's and early 2000's, and the opportunity to discover more of these centers was presented with the flyby of New Horizons in 2007. Previous authors (i.e. Spencer et al. 2007) have compared Galileo SSI and New Horizons LORRI images with similar viewing geometry, and have found multiple new potential features such as dark lava flows and bright plume deposits emplaced between the two flybys. The purpose of this study was to measure the extent of these changes on Io. Because an ISIS camera model does not yet exist for LORRI, a direct ratio image for comparison with the Galileo SSI images could not be created. By changing the stretch of the Galileo SSI images to match those of New Horizons as closely as possible, we were able to create a rough ratio image for the active center locations. We used these ratio images to measure the areal extent of the new deposits, taking careful precautions to measure more changes in shape than brightness, as brightness variations can be caused by certain surface materials being viewed at different phase angles between the Galileo and New Horizons flybys. This presentation will report our measurement findings. We then are able to use our measurements of the total area covered by new volcanic features to make estimates of the resurfacing rate of Io. Spencer, J.R. et al. (2007), Io Volcanism Seen by New Horizons: A Major Eruption of the Tvashtar Volcano, Science, 318, 240, DOI:10.1126/science.1147621.

  15. Scratching the Surface: Resurfacing Proteins to Endow New Properties and Function.

    PubMed

    Chapman, Alex M; McNaughton, Brian R

    2016-05-19

    Protein engineering is an emerging discipline that dovetails modern molecular biology techniques with high-throughput screening, laboratory evolution technologies, and computational approaches to modify sequence, structure, and, in some cases, function and properties of proteins. The ultimate goal is to develop new proteins with improved or designer functions for use in biotechnology, medicine, and basic research. One way to engineer proteins is to change their solvent-exposed regions through focused or random "protein resurfacing." In this review we explain what protein resurfacing is, and discuss recent examples of how this strategy is used to generate proteins with altered or broadened recognition profiles, improved stability, solubility, and expression, cell-penetrating ability, and reduced immunogenicity. Additionally we comment on how these properties can be further improved using chemical resurfacing approaches. Protein resurfacing will likely play an increasingly important role as more biologics enter clinical use, and we present some arguments to support this view. PMID:27203375

  16. Determining Statistically Significant Deviations from a Model Crater Production Function for Estimating Resurfacing Events

    NASA Astrophysics Data System (ADS)

    Weaver, B. P.; Hilbe, J. M.; Robbins, S. J.; Plesko, C. S.; Riggs, J. D.

    2015-05-01

    Many crater analysts will search for deviations of observed crater population data from model crater populations and treat those deviations as a modification event - usually resurfacing. We will discuss how to assign confidences for these deviations.

  17. Timescale of asteroid resurfacing by regolith convection resulting from the impact-induced global seismic shaking

    NASA Astrophysics Data System (ADS)

    Yamada, Tomoya M.; Ando, Kousuke; Morota, Tomokatsu; Katsuragi, Hiroaki

    2016-07-01

    A model for the asteroid resurfacing by regolith convection is built to estimate its timescale. In the model, regolith convection is driven by the impact-induced global seismic shaking. The model consists of three steps: (i) intermittent impact of meteoroids, (ii) impact-induced global vibration (seismic shaking), and (iii) vibration-induced regolith convection. In order to assess the feasibility of the resurfacing process driven by regolith convection, we estimate the resurfacing timescale as a function of the size of a target asteroid. In the estimate, a set of parameter values is assumed on the basis of previous works. However, some of them (e.g., seismic quality factor Q, seismic efficiency η, and seismic frequency f) are very uncertain. Although these parameter values might depend on asteroid size, we employ the standard values to estimate the representative behavior. To clarify the parameter dependences, we develop an approximated scaling form for the resurfacing timescale. According to the estimated result, we find that the regolith-convection-based resurfacing timescale is shorter than the mean collisional lifetime in most of the parameter uncertainty ranges. These parameter ranges are within those reported by previous works for small asteroids. This means that the regolith convection can be a possible mechanism for the asteroid resurfacing process.

  18. History of plains resurfacing in the Scandia region of Mars

    USGS Publications Warehouse

    Tanaka, Kenneth L.; Fortezzo, Corey M.; Hayward, Rosalyn K.; Rodriguez, J. Alexis P.; Skinner, James A.

    2011-01-01

    We present a preliminary photogeologic map of the Scandia region of Mars with the objective of reconstructing its resurfacing history. The Scandia region includes the lower section of the regional lowland slope of Vastitas Borealis extending about 500–1800 km away from Alba Mons into the Scandia sub-basin below −4800 m elevation. Twenty mapped geologic units express the diverse stratigraphy of the region. We particularly focus on the materials making up the Vastitas Borealis plains and its Scandia sub-region, where erosional processes have obscured stratigraphic relations and made the reconstruction of the resurfacing history particularly challenging. Geologic mapping implicates the deposition, erosion, and deformation/degradation of geologic units predominantly during Late Hesperian and Early Amazonian time (~3.6–3.3 Ga). During this time, Alba Mons was active, outflow channels were debouching sediments into the northern plains, and basal ice layers of the north polar plateau were accumulating. We identify zones of regional tectonic contraction and extension as well as gradation and mantling. Depressions and scarps within these zones indicate collapse and gradation of Scandia outcrops and surfaces at scales of meters to hundreds of meters. We find that Scandia Tholi display concentric ridges, rugged peaks, irregular depressions, and moats that suggest uplift and tilting of layered plains material by diapirs and extrusion, erosion, and deflation of viscous, sedimentary slurries as previously suggested. These appear to be long-lived features that both pre-date and post-date impact craters. Mesa-forming features may have similar origins and occur along the southern margin of the Scandia region, including near the Phoenix Mars Lander site. Distinctive lobate materials associated with local impact craters suggest impact-induced mobilization of surface materials. We suggest that the formation of the Scandia region features potentially resulted from crustal heating

  19. History of plains resurfacing in the Scandia region of Mars

    NASA Astrophysics Data System (ADS)

    Tanaka, Kenneth L.; Fortezzo, Corey M.; Hayward, Rosalyn K.; Rodriguez, J. Alexis P.; Skinner, James A.

    2011-09-01

    We present a preliminary photogeologic map of the Scandia region of Mars with the objective of reconstructing its resurfacing history. The Scandia region includes the lower section of the regional lowland slope of Vastitas Borealis extending about 500-1800 km away from Alba Mons into the Scandia sub-basin below -4800 m elevation. Twenty mapped geologic units express the diverse stratigraphy of the region. We particularly focus on the materials making up the Vastitas Borealis plains and its Scandia sub-region, where erosional processes have obscured stratigraphic relations and made the reconstruction of the resurfacing history particularly challenging. Geologic mapping implicates the deposition, erosion, and deformation/degradation of geologic units predominantly during Late Hesperian and Early Amazonian time (˜3.6-3.3 Ga). During this time, Alba Mons was active, outflow channels were debouching sediments into the northern plains, and basal ice layers of the north polar plateau were accumulating. We identify zones of regional tectonic contraction and extension as well as gradation and mantling. Depressions and scarps within these zones indicate collapse and gradation of Scandia outcrops and surfaces at scales of meters to hundreds of meters. We find that Scandia Tholi display concentric ridges, rugged peaks, irregular depressions, and moats that suggest uplift and tilting of layered plains material by diapirs and extrusion, erosion, and deflation of viscous, sedimentary slurries as previously suggested. These appear to be long-lived features that both pre-date and post-date impact craters. Mesa-forming features may have similar origins and occur along the southern margin of the Scandia region, including near the Phoenix Mars Lander site. Distinctive lobate materials associated with local impact craters suggest impact-induced mobilization of surface materials. We suggest that the formation of the Scandia region features potentially resulted from crustal heating

  20. Volcanic eruptions on Io: Heat flow, resurfacing, and lava composition

    NASA Technical Reports Server (NTRS)

    Blaney, Diana L.; Johnson, Torrence V.; Matson, Dennis L.; Veeder, Glenn J.

    1995-01-01

    We model an infrared outburst on Io as being due to a large, erupting lava flow which increased its area at a rate of 1.5 x 10(exp 5)/sq m and cooled from 1225 to 555 K over the 2.583-hr period of observation. The inferred effusion rate of 3 x 10(exp 5) cu m/sec for this eruption is very high, but is not unprece- dented on the Earth and is similar to the high eruption rates suggested for early lunar volcanism. Eruptions occur approxi- mately 6% of the time on Io. These eruptions provide ample resurfacing to explain Io's lack of impact craters. We suggest that the large total radiometric heat flow, 10(exp 14) W, and the size and temperature distribution of the thermal anomalies (McEwen et al. 1992; Veeder et al. 1994) can be accounted for by a series of silicate lava flows in various stages of cooling. We propose that the whole suite of Io's currently observed thermal anomalies was produced by multiple, high-eruptive-rate silicate flows within the past century.

  1. Kinematic radiography of the hip joint after hip resurfacing arthroplasty.

    PubMed

    Kawashima, Hiroki; Kajino, Yoshitomo; Kabata, Tamon; Tsuchiya, Hiroyuki; Sanada, Shigeru; Ichikawa, Katsuhiro

    2016-07-01

    This study aimed to evaluate the usefulness of dynamic radiography using a dynamic flat-panel detector (FPD) system after hip resurfacing arthroplasty (HRA). A total of 32 hips of 26 patients who underwent HRA were included. Sequential images of active abduction in the supine position and flexion in the 45° semilateral position were obtained using the FPD system. We examined the imaging findings of impingement between the acetabular component and femoral neck with cooperative motion at maximal exercise. Moreover, the central component coordinate of the acetabulum and femoral head sides was measured. For abduction motion, impingement was detected in two (6.3 %) hips between the superior portion of the femoral neck and acetabular component. For flexion motion, impingement was detected in 19 (59.4 %) hips. There were no findings of subluxation between the acetabular component and femoral neck after impingement, but cooperative motion of lumbar and pelvic flexion was observed. There was no significant difference in the center-to-center distance regardless of the presence or absence of impingement. Detailed postoperative kinematics of the hips after HRA showed that the proposed dynamic FPD system could reveal acquired impingement and cooperative motion as dynamic images and possibly reveal findings that would be unobservable using static images. PMID:27207072

  2. Resurfacing of Ganymede by Liquid-Water Volcanism

    NASA Technical Reports Server (NTRS)

    Showman, A. P.; Mosqueira, I.; Head, J. W., III

    2004-01-01

    A long-popular model for producing Ganymede s bright terrain involves flooding of low-lying graben with liquid water, slush, or warm, soft ice. The model suffers from major problems, however, including the absence of obvious near-surface heat sources, the negative buoyancy of liquid water, and the lack of a mechanism for confining the flows to graben floors. We show that topography - such as a global set of graben - causes subsurface (a hydrostatic) pressure gradients that can "suck" subsurface liquid water upward onto the floors of topographic lows (graben). As the low areas become full, the pressure gradients disappear and the resurfacing ceases. This provides an explanation for the observed straight dark-bright terrain boundaries: water cannot overflow the graben, so surfacing rarely embays craters and other rough topography. Subsurface liquid water must exist for the scenario to exist, of course, and is plausibly provided by tidal heating during an ancient orbital resonance. This abstract is a summary of Showman et al. recently submitted to Icarus.

  3. Experience with non-ablative fractional photothermolysis with a dual-mode laser device (1,440/1,320 nm): no considerable clinical effect on hypertrophic/acne scars and facial wrinkles.

    PubMed

    Babilas, Philipp; Schreml, Stephan; Eames, Tatiana; Hohenleutner, Ulrich; Landthaler, Michael; Hohenleutner, Silvia

    2011-07-01

    In the literature, non-ablative fractionated photothermolysis (nFP) is accredited with improvement of wrinkles and scars combined with a reduced downtime. The purpose of this work was to evaluate the impact of a combination laser (1,320/1,440 nm) for nFP on hypertrophic scars, acne scars, and facial wrinkles. Thirty-six patients suffering from hypertrophic scars (n = 7), acne scars (n = 9), and wrinkles (n = 20) were treated using a combination Nd:YAG laser [λ(em) = 1,320 and 1,440 nm, pulse duration: 3-ms single pulse, fluence: 8.0-9.0 J/cm(2) (1,320 nm); 2.0-2.5 J/cm(2) (1,440 nm)]. The appearance of the treated condition was evaluated in a retrospective study by two blinded investigators based on follow-up photographs and by patient self-assessment. The frequency of side-effects was also assessed. Both patients and blinded observers rated the treatment results for hypertrophic scars and acne scars as slight improvement, and for wrinkles as equal as compared to baseline. No serious side-effects were reported. The light device used did not lead to a considerable clinical improvement of hypertrophic scars, acne scars, or wrinkles in this study. PMID:21318344

  4. Hip resurfacing arthroplasty: A new method to assess and quantify learning phase.

    PubMed

    Aulakh, T S; Jayasekera, N; Singh, R; Patel, A; Kuiper, J H; Richardson, J B

    2014-09-01

    Hip resurfacing had initially gained acceptance and popularity as it helps preserve femoral bone stock. In this study we tried to answer the following questions; 1. Whether there is a learning curve for hip resurfacing? 2. Is it present in surgeons from non-developer centres? 3. Is it present in surgeons from developer centres as well? The Oswestry outcome centre was setup to serve an independent international registry for collecting, analysing and reporting outcomes following hip resurfacing. Over a 10 year period, 4535 patients (5000 hips) were recruited from different countries and within the UK from different centres in this study by 139 surgeons from 37 different countries. Our study has shown that function can be used to assess the level of surgical competence. The results from this multilevel analysis have helped to answer the questions posed in the introduction. Hip resurfacing is a surgical procedure with a learning phase and this learning effect is more pronounced in non-developer surgeons as compared to developer surgeons. Hip scores can be used to assess proficiency and competence of surgeons undertaking hip resurfacing arthroplasty. PMID:26280614

  5. Periprosthetic humeral fracture after Copeland resurfacing and the role of revision arthroplasty: A report of three cases

    PubMed Central

    MacLean, Simon Bruce Murdoch; Mangat, Karanjit; Nandra, Rajpal; Kalogrianitis, Socrates

    2015-01-01

    Follow-up series of the Copeland resurfacing hemiarthroplasty have reported few postoperative fractures around the prosthesis. We report three cases of periprosthetic fracture around a Copeland resurfacing arthroplasty. Due to prosthetic loosening and tuberosity comminution, all cases were managed with revision shoulder arthroplasty. All patients had good functional outcome and range of movement on early follow-up. PMID:26622129

  6. Does prosthesis design affect the need for secondary resurfacing in total knee arthroplasty?

    PubMed Central

    Rotigliano, Niccolò; Hirschmann, Michael T.

    2016-01-01

    Aims and Objectives: The purpose of this retrospective consecutive study was to compare the rate of secondary resurfacing in consecutive series of five different TKA systems. It was our hypothesis that different brands of TKA show different rates of secondary resurfacing. Materials and Methods: A retrospective study was performed on data from patients who underwent TKA without primary patellar resurfacing from 2004 to 2012 in an university affiliated hospital. The study cohort included 784 patients (m:f=302:482, mean age at surgery±SD 71±10) operated with TKA during this period. Five different cruciate-retaining TKA systems were used in consecutives series. These were the following: A) Triathlon, Stryker, Switzerland (n=296), B) PFC Sigma, DepuySynthes, Switzerland (n=215), C) LCS, DepuySynthes, Switzerland (n=80), D) Balansys, Mathys, Bettlach, Switzerland (n=129), E) Duracon, Stryker, Switzerland (n=64). Data was retrospectively obtained from our different hospital archives. Patients demographics, age at surgery, type of total knee arthroplasty were noted. In addition, the data were screened for a secondary resurfacing in each patient. On anterior-posterior, lateral and skyline view radiographs different measurements were performed. TKA component position was assessed on radiographs with respect to "The knee society total knee arthroplasty roentgenographic evaluation and scoring system (TKA-RESS). Pearson Chi square test was used to compare differences between groups (p<0.05). There was no significant difference between the groups in terms of age, gender, and radiological outcomes. Results: Twenty-six of 784 patients (3.3%) underwent secondary resurfacing due to patellofemoral pain during follow-up. In group A four of 296 patients (1.4%), in group B fifteen of 215 patients (7%), in group C four of 80 patients (5%), in group D two of 129 patients (1.6%), in group E one of 64 patients (1.6%) underwent secondary patellar resurfacing during follow-up. There was a

  7. Computer navigation vs conventional mechanical jig technique in hip resurfacing arthroplasty: a meta-analysis based on 7 studies.

    PubMed

    Liu, Hao; Li, Lin; Gao, Wei; Wang, Meilin; Ni, Chunhui

    2013-01-01

    The studies on the accuracy of femoral component in hip resurfacing arthroplasty with the help of computer-assisted navigation were not consistent. This study aims to assess at the functional outcomes after computer navigation in hip resurfacing arthroplasty by systematically reviewing and meta-analyzing the data, which were searched up to December 2011 in PubMed, MEDLINE, EMBASE, MetaMed, EBSCO HOST, and the Web site of Google scholar. Totally, 197 articles about hip resurfacing arthroplasty were collected; finally, 7 articles met the inclusion criteria and were included in this meta-analysis (520 patients with 555 hip resurfacing arthroplasty). The odds ratio for the number of outliers was 0.155 (95% confidence interval, 0.048-0.498; P < .003). In conclusion, this meta-analysis suggests that the computer-assisted navigation system makes the femoral component positioning in hip resurfacing arthroplasty easier and more precise. PMID:22771091

  8. Erbium:YAG laser resurfacing increases skin permeability and the risk of excessive absorption of antibiotics and sunscreens: the influence of skin recovery on drug absorption.

    PubMed

    Lee, Woan-Ruoh; Shen, Shing-Chuan; Al-Suwayeh, Saleh A; Li, Yi-Ching; Fang, Jia-You

    2012-06-01

    While laser skin resurfacing is expected to result in reduced barrier function and increased risk of drug absorption, the extent of the increment has not yet been systematically investigated. We aimed to establish the skin permeation profiles of tetracycline and sunscreens after exposure to the erbium:yttrium-aluminum-garnet (Er:YAG) laser during postoperative periods. Physiological and histopathological examinations were carried out for 5 days after laser treatment on nude mice. Percutaneous absorption of the permeants was determined by an in vitro Franz cell. Ablation depths varied in reaching the stratum corneum (10 μm, 2.5 J/cm²) to approach the epidermis (25 μm, 6.25 J/cm²) and upper dermis (40 μm, 10 J/cm²). Reepithelialization evaluated by transepidermal water loss was complete within 2-4 days and depended on the ablation depth. Epidermal hyperplasia was observed in the 40-μm-treated group. The laser was sufficient to disrupt the skin barrier and allow the transport of the permeants into and across the skin. The laser fluence was found to play an important role in modulating skin absorption. A 25-μm ablation depth increased tetracycline flux 84-fold. A much smaller enhancement (3.3-fold) was detected for tetracycline accumulation within the skin. The laser with different fluences produced enhancement of oxybenzone skin deposition of 3.4-6.4-fold relative to the untreated group. No penetration across the skin was shown regardless of whether titanium dioxide was applied to intact or laser-treated skin. However, laser resurfacing increased the skin deposition of titanium dioxide from 46 to 109-188 ng/g. Tetracycline absorption had recovered to the level of intact skin after 5 days, while more time was required for oxybenzone absorption. The in vivo skin accumulation and plasma concentration revealed that the laser could increase tetracycline absorption 2-3-fold. The experimental results indicated that clinicians should be cautious when determining the

  9. Extent, age, and resurfacing history of the northern smooth plains on Mercury from MESSENGER observations

    NASA Astrophysics Data System (ADS)

    Ostrach, Lillian R.; Robinson, Mark S.; Whitten, Jennifer L.; Fassett, Caleb I.; Strom, Robert G.; Head, James W.; Solomon, Sean C.

    2015-04-01

    MESSENGER orbital images show that the north polar region of Mercury contains smooth plains that occupy ~7% of the planetary surface area. Within the northern smooth plains (NSP) we identify two crater populations, those superposed on the NSP ("post-plains") and those partially or entirely embayed ("buried"). The existence of the second of these populations is clear evidence for volcanic resurfacing. The post-plains crater population reveals that the NSP do not exhibit statistically distinguishable subunits on the basis of crater size-frequency distributions, nor do measures of the areal density of impact craters reveal volcanically resurfaced regions within the NSP. These results suggest that the most recent outpouring of volcanic material resurfaced the majority of the region, and that this volcanic flooding emplaced the NSP over a relatively short interval of geologic time, perhaps 100 My or less. Stratigraphic embayment relationships within the buried crater population, including partial crater flooding and the presence of smaller embayed craters within the filled interiors of larger craters and basins, indicate that a minimum of two episodes of volcanic resurfacing occurred. From the inferred rim heights of embayed craters, we estimate the NSP to be regionally 0.7-1.8 km thick, with a minimum volume of volcanic material of 4 × 106 to 107 km3. Because of the uncertainty in the impact flux at Mercury, the absolute model age of the post-plains volcanism could be either ∼3.7 or ∼2.5 Ga, depending on the chronology applied.

  10. The Tribology of Explanted Hip Resurfacings Following Early Fracture of the Femur

    PubMed Central

    Lord, James K.; Langton, David J.; Nargol, Antoni V.F.; Meek, R.M. Dominic; Joyce, Thomas J.

    2015-01-01

    A recognized issue related to metal-on-metal hip resurfacings is early fracture of the femur. Most theories regarding the cause of fracture relate to clinical factors but an engineering analysis of failed hip resurfacings has not previously been reported. The objective of this work was to determine the wear volumes and surface roughness values of a cohort of retrieved hip resurfacings which were removed due to early femoral fracture, infection and avascular necrosis (AVN). Nine resurfacing femoral heads were obtained following early fracture of the femur, a further five were retrieved due to infection and AVN. All fourteen were measured for volumetric wear using a co-ordinate measuring machine. Wear rates were then calculated and regions of the articulating surface were divided into “worn” and “unworn”. Roughness values in these regions were measured using a non-contacting profilometer. The mean time to fracture was 3.7 months compared with 44.4 months for retrieval due to infection and AVN. Average wear rates in the early fracture heads were 64 times greater than those in the infection and AVN retrievals. Given the high wear rates of the early fracture components, such wear may be linked to an increased risk of femoral neck fracture. PMID:26501331

  11. The Tribology of Explanted Hip Resurfacings Following Early Fracture of the Femur.

    PubMed

    Lord, James K; Langton, David J; Nargol, Antoni V F; Meek, R M Dominic; Joyce, Thomas J

    2015-01-01

    A recognized issue related to metal-on-metal hip resurfacings is early fracture of the femur. Most theories regarding the cause of fracture relate to clinical factors but an engineering analysis of failed hip resurfacings has not previously been reported. The objective of this work was to determine the wear volumes and surface roughness values of a cohort of retrieved hip resurfacings which were removed due to early femoral fracture, infection and avascular necrosis (AVN). Nine resurfacing femoral heads were obtained following early fracture of the femur, a further five were retrieved due to infection and AVN. All fourteen were measured for volumetric wear using a co-ordinate measuring machine. Wear rates were then calculated and regions of the articulating surface were divided into "worn" and "unworn". Roughness values in these regions were measured using a non-contacting profilometer. The mean time to fracture was 3.7 months compared with 44.4 months for retrieval due to infection and AVN. Average wear rates in the early fracture heads were 64 times greater than those in the infection and AVN retrievals. Given the high wear rates of the early fracture components, such wear may be linked to an increased risk of femoral neck fracture. PMID:26501331

  12. Hip resurfacing arthroplasty: mid-term results in 486 cases and current indication in our institution.

    PubMed

    Ribas, Manuel; Cardenas, Carlomagno; Astarita, Emanuele; Moya, Esther; Bellotti, Vittorio

    2014-01-01

    In the previous decade, metal-on-metal hip resurfacing has been considered an attractive option and theoretically advantageous over conventional total hip arthroplasty, especially in young active patients. Different authors have reported favourable mid-term clinical and functional results with acceptable survival rates. Proper indication and planning, as accurate technical execution have been advocated to be crucial elements for success.Concerns regarding serum metal ion levels and possible clinical implications have led in the last years to a decline in the use of metal-on-metal hip resurfacing and metal-on-metal bearings in general.The aim of this study is to present the results of our first 486 cases of hybrid hip resurfacing arthroplasties with a second generation cementing technique, and to describe our current restricted indication of this type of prosthesis, in the light of recent findings in the literature about the possible complications related to metallosis or improper patient selection. Global survivorship of our series was 97.9% at a mean follow-up of 7.2 years.In the second season of our experience the indication is restrictive. The candidate for a resurfacing hip replacement is a young and active male patient, with good bone quality, that has been made aware of the risks and benefits of this type of prosthesis. PMID:24970031

  13. Fracture of the femoral alignment stem of a hip resurfacing arthroplasty. A case report.

    PubMed

    Bhutta, Mohammed A; Shah, Vinod B

    2011-02-01

    Metal-on-metal hip resurfacing arthroplasty has become increasingly popular for the treatment of osteoarthritis in a younger patient population. While the initial complication of femoral neck fracture is being addressed, we describe a fracture of the femoral alignment stem in a component two years from the primary procedure. PMID:21473460

  14. Surgical Ablation of Atrial Fibrillation.

    PubMed

    Ramlawi, Basel; Abu Saleh, Walid K

    2015-01-01

    The Cox-maze procedure for the restoration of normal sinus rhythm, initially developed by Dr. James Cox, underwent several iterations over the years. The main concept consists of creating a series of transmural lesions in the right and left atria that disrupt re-entrant circuits responsible for propagating the abnormal atrial fibrillation rhythm. The left atrial appendage is excluded as a component of the Maze procedure. For the first three iterations of the Cox- maze procedure, these lesions were performed using a surgical cut-and-sew approach that ensured transmurality. The Cox-Maze IV is the most currently accepted iteration. It achieves the same lesion set of the Cox- maze III but uses alternative energy sources to create the transmural lesions, potentially in a minimally invasive approach on the beating heart. High-frequency ultrasound, microwave, and laser energy have all been used with varying success in the past. Today, bipolar radiofrequency heat or cryotherapy cooling are the most accepted sources for creating linear lesions with consistent safety and transmurality. The robust and reliable nature of these energy delivery methods has yielded a success rate reaching 90% freedom from atrial fibrillation at 12 months. Such approaches offer a significant long-term advantage over catheter-based ablation, especially in patients having longstanding, persistent atrial fibrillation with characteristics such as dilated left atrial dimensions, poor ejection fraction, and failed catheter ablation. Based on these improved results, there currently is significant interest in developing a hybrid ablation strategy that incorporates the superior transmural robust lesions of surgical ablation, the reliable stroke prevention potential of epicardial left atrial appendage exclusion, and sophisticated mapping and confirmatory catheter-based ablation technology. Such a minimally invasive hybrid strategy for ablation may lead to the development of multidisciplinary "Afib teams" to

  15. Lessons from computer simulations of ablation of atrial fibrillation.

    PubMed

    Jacquemet, Vincent

    2016-05-01

    This paper reviews the simulations of catheter ablation in computer models of the atria, from the first attempts to the most recent anatomical models. It describes how postulated substrates of atrial fibrillation can be incorporated into mathematical models, how modelling studies can be designed to test ablation strategies, what their current trade-offs and limitations are, and what clinically relevant lessons can be learnt from these simulations. Drawing a parallel between clinical and modelling studies, six ablation targets are considered: pulmonary vein isolation, linear ablation, ectopic foci, complex fractionated atrial electrogram, rotors and ganglionated plexi. The examples presented for each ablation target illustrate a major advantage of computer models, the ability to identify why a therapy is successful or not in a given atrial fibrillation substrate. The integration of pathophysiological data to create detailed models of arrhythmogenic substrates is expected to solidify the understanding of ablation mechanisms and to provide theoretical arguments supporting substrate-specific ablation strategies. PMID:26846178

  16. Laser ablation in analytical chemistry - A review

    SciTech Connect

    Russo, Richard E.; Mao, Xianglei; Liu, Haichen; Gonzalez, Jhanis; Mao, Samuel S.

    2001-10-10

    Laser ablation is becoming a dominant technology for direct solid sampling in analytical chemistry. Laser ablation refers to the process in which an intense burst of energy delivered by a short laser pulse is used to sample (remove a portion of) a material. The advantages of laser ablation chemical analysis include direct characterization of solids, no chemical procedures for dissolution, reduced risk of contamination or sample loss, analysis of very small samples not separable for solution analysis, and determination of spatial distributions of elemental composition. This review describes recent research to understand and utilize laser ablation for direct solid sampling, with emphasis on sample introduction to an inductively coupled plasma (ICP). Current research related to contemporary experimental systems, calibration and optimization, and fractionation is discussed, with a summary of applications in several areas.

  17. Topographic and Morphologic Evidence for Flooding of Ganymede's Resurfaced Terrains by Low-Viscosity Water-Ice Lavas

    NASA Technical Reports Server (NTRS)

    McKinnon, W. B.; Schenk, P. M.; Moore, J. M.

    2001-01-01

    Topographic mapping in at least three distinct regions of Ganymede reveals that smooth terrains are flat and are topographically depressed. This and embayment relationships are consistent with volcanic resurfacing. Additional information is contained in the original extended abstract.

  18. Laser-ablation processes

    SciTech Connect

    Dingus, R.S.

    1992-01-01

    The various mechanisms by which ablation of materials can be induced with lasers are discussed in this paper. The various ablation processes and potential applications are reviewed from the threshold for ablation up to fluxes of about 10{sup 13} W/cm{sup 2}, with emphasis on three particular processes; namely, front-surface spallation, two-dimensional blowoff, and contained vaporization.

  19. Chemically assisted laser ablation ICP mass spectrometry.

    PubMed

    Hirata, Takafumi

    2003-01-15

    A new laser ablation technique combined with a chemical evaporation reaction has been developed for elemental ratio analysis of solid samples using an inductively coupled plasma mass spectrometer (ICPMS). Using a chemically assisted laser ablation (CIA) technique developed in this study, analytical repeatability of the elemental ratio measurement was successively improved. To evaluate the reliability of the CLA-ICPMS technique, Pb/U isotopic ratios were determined for zircon samples that have previously been analyzed by other techniques. Conventional laser ablation for Pb/U shows a serious elemental fractionation during ablation mainly due to the large difference in elemental volatility between Pb and U. In the case of Pb/U ratio measurement, a Freon R-134a gas (1,1,1,2-tetrafluoroethane) was introduced into the laser cell as a fluorination reactant. The Freon gas introduced into the laser cell reacts with the ablated sample U, and refractory U compounds are converted to a volatile U fluoride compound (UF6) under the high-temperature condition at the ablation site. This avoids the redeposition of U around the ablation pits. Although not all the U is reacted with Freon, formation of volatile UF compounds improves the transmission efficiency of U. Typical precision of the 206Pb/238U ratio measurement is 3-5% (2sigma) for NIST SRM 610 and Nancy 91500 zircon standard, and the U-Pb age data obtained here show good agreement within analytical uncertainties with the previously reported values. Since the observed Pb/U ratio for solid samples is relatively insensitive to laser power and ablation time, optimization of ablation conditions or acquisition parameters no longer needs to be performed on a sample-to-sample basis. PMID:12553756

  20. Ten different hip resurfacing systems: biomechanical analysis of design and material properties

    PubMed Central

    Kleinhans, Jennifer A.; Menge, Michael; Kretzer, Jan Philippe

    2008-01-01

    This study gives an overview of the main macro- and microstructural differences of ten commercially available total hip resurfacing implants. The heads and cups of resurfacing hip implants from ten different manufacturers were analysed. The components were measured in a coordinate measuring machine. The microstructure of the heads and cups was inspected by scanning electron microscopy. The mean radial clearance was 84.86 μm (range: 49.47–120.93 μm). The implants were classified into three groups (low, medium and high clearance). All implants showed a deviation of roundness of less than 10 μm. It was shown that all implants differ from each other and a final conclusion about the ideal design and material combination cannot be given based on biomechanical data. Widespread use of specific designs can only be recommended if clinical long-term follow-up studies are performed and analysed for each design. PMID:18600323

  1. Another Estimate for the Percentage of Partly Embayed Craters in Equilibrium Resurfacing

    NASA Astrophysics Data System (ADS)

    Muinonen, P. J.

    1996-03-01

    When choosing between different scenarios of Venus' resurfacing history, one of the objections against an Equilibrium Resurfacing Model (ERM) is an apparent lack of craters that have suffered a partial embayment by lava flows of outside origin. Any test of ERM so far, be it numeric or analytic in nature, has failed to predict anything even near the observed ~5% of partly embayed craters (PECs) without violating the statistics of crater distribution. This study is mainly based on straightening out as many as possible of the simplifications that have been employed while estimating the statistical implications of the ERM. As a result, the expectation value for PECs falls to less than 10% from previous ~30%.

  2. ELIGIBILITY FOR THE HIP-RESURFACING ARTHROPLASTY PROCEDURE: AN EVALUATION ON 592 HIPS

    PubMed Central

    Queiroz, Roberto Dantas; Faria, Rafael Salomon Silva; Duarte, David Marcelo; Takano, Marcelo Itiro; Sugiyama, Mauricio Morita

    2015-01-01

    Objective: To investigate the percentage of ideal patients who would be eligible for hip-resurfacing surgery at a reference service for hip arthroplasty. Methods: Out of all the cases of hip arthroplasty operated at Hospital do Servidor Público Estadual de São Paulo (HSPE) between January 2009 and December 2010, we assessed a total of 592 procedures that would fit the criteria for indication for resurfacing arthroplasty, after clinical and radiological evaluation according to the criteria established by the Food and Drug Administration (FDA) and by Seyler et al. Results: Among the total number of hip replacement arthroplasty cases, 5.74% of the patients were eligible. Among the patients who underwent primary arthroplasty, we found that 8.23% presented ideal conditions for this procedure. Conclusion: The study demonstrated that this type of surgery still has a limited role among hip surgery methods. PMID:27047851

  3. Failure of a novel ceramic-on-ceramic hip resurfacing prosthesis.

    PubMed

    Matharu, Gulraj S; Daniel, Joseph; Ziaee, Hena; McMinn, Derek J W

    2015-03-01

    We report the early failure of five ceramic-on-ceramic hip resurfacings (CoCHRs). The ceramic used for the acetabular liner was a novel ceramic-composite (two thirds polyurethane and one third alumina ceramic). All cases were revised for increasing metal ion levels (blood cobalt 3.93-208.0 μg/l and chromium 1.57-17.5 μg/l) due to ceramic liner fracture and/or accelerated wear of the ceramic femoral head coating. Patients underwent bearing exchange and revision using primary hip arthroplasty implants at a mean of 3.0 years following CoCHR. Intraoperatively all patients had metallosis. At 1 to 2 years of follow-up blood metal ions normalized with no complications. We do not recommend this particular type of ceramic-on-ceramic bearing for hip resurfacing. PMID:25453631

  4. "Active" and "Passive" Lava Resurfacing Processes on Io: A Comparative Study of Loki Patera and Prometheus

    NASA Technical Reports Server (NTRS)

    Davies, A. G.; Matson, D. L.; Leone, G.; Wilson, L.; Keszthelyi, L. P.

    2004-01-01

    Studies of Galileo Near Infrared Mapping Spectrometer (NIMS) data and ground based data of volcanism at Prometheus and Loki Patera on Io reveal very different mechanisms of lava emplacement at these two volcanoes. Data analyses show that the periodic nature of Loki Patera s volcanism from 1990 to 2001 is strong evidence that Loki s resurfacing over this period resulted from the foundering of a crust on a lava lake. This process is designated passive , as there is no reliance on sub-surface processes: the foundering of the crust is inevitable. Prometheus, on the other hand, displays an episodicity in its activity which we designate active . Like Kilauea, a close analog, Prometheus s effusive volcanism is dominated by pulses of magma through the nearsurface plumbing system. Each system affords views of lava resurfacing processes through modelling.

  5. Laser ablation of blepharopigmentation

    SciTech Connect

    Tanenbaum, M.; Karas, S.; McCord, C.D. Jr. )

    1988-01-01

    This article discusses laser ablation of blepharopigmentation in four stages: first, experimentally, where pigment vaporization is readily achieved with the argon blue-green laser; second, in the rabbit animal model, where eyelid blepharopigmentation markings are ablated with the laser; third, in human subjects, where the argon blue-green laser is effective in the ablation of implanted eyelid pigment; and fourth, in a case report, where, in a patient with improper pigment placement in the eyelid, the laser is used to safely and effectively ablate the undesired pigment markings. This article describes in detail the new technique of laser ablation of blepharopigmentation. Potential complications associated with the technique are discussed.

  6. Volcanically embayed craters on Venus: testing the catastrophic and equilibrium resurfacing models

    NASA Astrophysics Data System (ADS)

    Ivanov, M. A.; Head, J. W.

    2015-02-01

    Two major types of volcanic units, older regional plains and younger lobate plains, make up ~50% of the surface of Venus and represent different epochs of volcanism. The abundance of impact craters partially embayed from the exterior by each of these two types of units permits the testing of the key points of the model of equilibrium resurfacing. The proportion of craters embayed by the older regional plains is ~3%, which requires the typical size of a volcanic resurfacing event to be ~2700 km (~25° of angular diameter) in the framework of the equilibrium model. These event dimensions are inconsistent with the quasi-random spatial distribution of the craters. The proportion of craters embayed by younger lobate plains is 33%, which can be achieved if the characteristic size of the resurfacing event is less than ~160 km (~1.5° of angular diameter). Events of this size do not disturb the character of the spatial distribution of craters. We conclude that the style of volcanic resurfacing on Venus has changed significantly during its observable portion of the geologic history. During the global volcanic regime when regional plains were emplaced, volcanism acted in large regions and the process of formation of regional plains was more intensive than accumulation of impact craters. This led to the very small proportion of embayed craters (~3%). Later, during the network-rifting and volcanism regime (emplacement of lobate plains), volcanic sources were localized at distinctive centers, the net volcanic intensity decreased and became comparable to the rate of accumulation of craters, which resulted in much larger percentage (33%) of craters embayed by lobate plains.

  7. Measurement of the migration of a focal knee resurfacing implant with radiostereometry

    PubMed Central

    2014-01-01

    Background and purpose Articular resurfacing metal implants have been developed to treat full-thickness localized articular cartilage defects. Evaluation of the fixation of these devices is mandatory. Standard radiostereometry (RSA) is a validated method for evaluation of prosthetic migration, but it requires that tantalum beads are inserted into the implant. For technical reasons, this is not possible for focal articular resurfacing components. In this study, we therefore modified the tip of an articular knee implant and used it as a marker for RSA, and then validated the method. Material and methods We modified the tip of a resurfacing component into a hemisphere with a radius of 3 mm, marked it with a 1.0-mm tantalum marker, and implanted it into a sawbone marked with 6 tantalum beads. Point-motion RSA of the “hemisphere bead” using standard automated RSA as the gold standard was compared to manual measurement of the tip hemisphere. 20 repeated stereograms with gradual shifts of position of the specimen between each double exposure were used for the analysis. The tip motion was compared to the point motion of the hemisphere bead to determine the accuracy and precision. Results The accuracy of the manual tip hemisphere method was 0.08–0.19 mm and the precision ranged from 0.12 mm to 0.33 mm. Interpretation The accuracy and precision for translations is acceptable when using a small hemisphere at the tip of a focal articular knee resurfacing implant instead of tantalum marker beads. Rotations of the implant cannot be evaluated. The method is accurate and precise enough to allow detection of relevant migration, and it will be used for future clinical trials with the new implant. PMID:24286562

  8. Persistent atrial fibrillation ablation: conventional versus driver-guided strategy.

    PubMed

    Lim, Han S; Sacher, Frédéric; Zellerhoff, Stephan; Jesel, Laurence; Shah, Ashok J; Komatsu, Yuki; Daly, Matthew; Denis, Arnaud; Derval, Nicolas; Hocini, Mélèze; Jaïs, Pierre; Haïssaguerre, Michel

    2015-01-01

    While pulmonary vein isolation for paroxysmal atrial fibrillation (AF) is highly effective, catheter ablation for persistent AF remains a challenge with varying clinical success reported. Several ablation techniques have been proposed to target persistent AF, with the additional ablation of complex fractionated electrograms and linear lesions shown to provide incremental success to pulmonary vein isolation alone. Recently, several studies have suggested the presence of localized drivers (re-entrant or focal) in AF. By targeting these drivers, clinical outcomes may be maintained while minimizing the extent of ablation. This article will focus on the conventional stepwise ablation approach for persistent AF versus driver-guided ablation with the use of newer mapping technologies. PMID:26610158

  9. Dione's resurfacing history as determined from a global impact crater database

    NASA Astrophysics Data System (ADS)

    Kirchoff, Michelle R.; Schenk, Paul

    2015-08-01

    Saturn's moon Dione has an interesting and unique resurfacing history recorded by the impact craters on its surface. In order to further resolve this history, we compile a crater database that is nearly global for diameters (D) equal to and larger than 4 km using standard techniques and Cassini Imaging Science Subsystem images. From this database, spatial crater density maps for different diameter ranges are generated. These maps, along with the observed surface morphology, have been used to define seven terrain units for Dione, including refinement of the smooth and "wispy" (or faulted) units from Voyager observations. Analysis of the terrains' crater size-frequency distributions (SFDs) indicates that: (1) removal of D ≈ 4-50 km craters in the "wispy" terrain was most likely by the formation of D ≳ 50 km craters, not faulting, and likely occurred over a couple billion of years; (2) resurfacing of the smooth plains was most likely by cryovolcanism at ∼2 Ga; (3) most of Dione's largest craters (D ⩾ 100 km), including Evander (D = 350 km), may have formed quite recently (<2 Ga), but are still relaxed, indicating Dione has been thermally active for at least half its history; and (4) the variation in crater SFDs at D ≈ 4-15 km is plausibly due to different levels of minor resurfacing (mostly subsequent large impacts) within each terrain.

  10. Patellar resurfacing in total knee arthroplasty: functional outcome differs with different outcome scores

    PubMed Central

    Aunan, Eirik; Næss, Grethe; Clarke-Jenssen, John; Sandvik, Leiv; Kibsgård, Thomas Johan

    2016-01-01

    Background and purpose — Recent research on outcomes after total knee arthroplasty (TKA) has raised the question of the ability of traditional outcome measures to distinguish between treatments. We compared functional outcomes in patients undergoing TKA with and without patellar resurfacing, using the knee injury and osteoarthritis outcome score (KOOS) as the primary outcome and 3 traditional outcome measures as secondary outcomes. Patients and methods — 129 knees in 115 patients (mean age 70 (42–82) years; 67 female) were evaluated in this single-center, randomized, double-blind study. Data were recorded preoperatively, at 1 year, and at 3 years, and were assessed using repeated-measures mixed models. Results — The mean subscores for the KOOS after surgery were statistically significantly in favor of patellar resurfacing: sport/recreation, knee-related quality of life, pain, and symptoms. No statistically significant differences between the groups were observed with the Knee Society clinical rating system, with the Oxford knee score, and with visual analog scale (VAS) for patient satisfaction. Interpretation — In the present study, the KOOS—but no other outcome measure used—indicated that patellar resurfacing may be beneficial in TKA. PMID:26540368

  11. Influence of ingrowth regions on bone remodelling around a cementless hip resurfacing femoral implant.

    PubMed

    Haider, Ifaz T; Speirs, Andrew D; Beaulé, Paul E; Frei, Hanspeter

    2015-01-01

    Hip resurfacing arthroplasty is an alternative to traditional hip replacement that can conserve proximal bone stock and has gained popularity but bone resorption may limit implant survival and remains a clinical concern. The goal of this study was to analyze bone remodelling patterns around an uncemented resurfacing implant and the influence of ingrowth regions on resorption. A computed tomography-derived finite element model of a proximal femur with a virtually implanted resurfacing component was simulated under peak walking loads. Bone ingrowth was simulated by six interface conditions: fully bonded; fully friction; bonded cap with friction stem; a small bonded region at the stem-cup intersection with the remaining surface friction; fully frictional, except for a bonded band along the distal end of the cap and superior half of the cap bonded with the rest frictional. Interface condition had a large influence on remodelling patterns. Bone resorption was minimized when no ingrowth occurred at the bone-implant interface. Bonding only the superior half of the cap increased bone resorption slightly but allowed for a large ingrowth region to improve secondary stability. PMID:24697332

  12. Effects of acetabular resurfacing component material and fixation on the strain distribution in the pelvis.

    PubMed

    Thompson, M S; Northmore-Ball, M D; Tanner, K E

    2002-01-01

    A 3D finite element (FE) model of an implanted pelvis was developed as part of a project investigating an all-polymer hip resurfacing design. The model was used to compare this novel design with a metal-on-metal design in current use and a metal-on-polymer design typical of early resurfacing implants. The model included forces representing the actions of 22 muscles as well as variable cancellous bone stiffness and variable cortical shell thickness. The hip joint reaction force was applied via contact modelled between the femoral and acetabular components of the resurfacing prosthesis. Five load cases representing time points through the gait cycle were analysed. The effect of varying fixation conditions was also investigated. The highest cancellous bone strain levels were found at mid-stance, not heel-strike. Remote from the acetabulum there was little effect of prosthesis material and fixation upon the von Mises stresses and maximum principal strains. Implant material appeared to have little effect upon cancellous bone strain failure with both bended and unbonded bone-implant interfaces. The unbonded implants increased stresses in the subchondral bone at the centre of the acetabulum and increased cancellous bone loading, resembling behaviour obtained previously for the intact acetabulum. PMID:12206520

  13. Biomechanical optimization of subject-specific implant positioning for femoral head resurfacing to reduce fracture risk.

    PubMed

    Miles, Brad; Kolos, Elizabeth; Appleyard, Richard; Theodore, Willy; Zheng, Keke; Li, Qing; Ruys, Andrew J

    2016-07-01

    Peri-prosthetic femoral neck fracture after femoral head resurfacing can be either patient-related or surgical technique-related. The study aimed to develop a patient-specific finite element modelling technique that can reliably predict an optimal implant position and give minimal strain in the peri-prosthetic bone tissue, thereby reducing the risk of peri-prosthetic femoral neck fracture. The subject-specific finite element modelling was integrated with optimization techniques including design of experiments to best possibly position the implant for achieving minimal strain for femoral head resurfacing. Sample space was defined by varying the floating point to find the extremes at which the cylindrical reaming operation actually cuts into the femoral neck causing a notch during hip resurfacing surgery. The study showed that the location of the maximum strain, for all non-notching positions, was on the superior femoral neck, in the peri-prosthetic bone tissue. It demonstrated that varus positioning resulted in a higher strain, while valgus positioning reduced the strain, and further that neutral version had a lower strain. PMID:27098752

  14. Temperature, age and crust thickness distributions of Loki Patera on Io: implications for resurfacing mechanism

    NASA Technical Reports Server (NTRS)

    Davies, A. G.

    2003-01-01

    A high-spatial-resolution, multi-wavelength observation by the Galileo NIMS instrument has been analysed to determine the temperature and area distribution of a large portion of the ionian volcano Loki Patera. The temperatures of the cooler components from a two-temperature fit to the data can be used to determine ages of the surface. The age of the floor along a profile across the floor of the caldera ranges from 10 to 80 days. This puts the start of the resurfacing in July/early August 2001, yielding a resurfacing rate of approximately 1 km/day, with the new lava spreading from the SW corner of the caldera in a NE direction. This rate is consistent with resurfacing by foundering of the crust on a lava lake. However,the temperature distribution may also result from the emplacement of flows. Implied crust thicknesses (derived using a lava cooling model) range from 2.6 to 0.9 m.

  15. Transplacental passage of metal ions in women with hip resurfacing: no teratogenic effects observed.

    PubMed

    deSouza, Ruth-Mary; Wallace, David; Costa, Matthew L; Krikler, Stephen J

    2012-01-01

    Over recent years, hip resurfacing has been performed in young, active patients, including women in their child bearing years. Current work investigating the transplacental passage of metal ions (cobalt and chromium) suggests significant passage of ions across the placenta in mothers with metal on metal hip resurfacing. In vitro studies show that cobalt and chromium can create DNA and chromosome damage in human cells. The consequences of this ion transfer on the child during fetal development and thereafter have not been fully quantified. We report on 3 patients with metal on metal hip resurfacings who had the prosthesis in situ during pregnancy. Our data show that umbilical cord blood chromium levels are under a quarter of the maternal serum levels. Cord blood cobalt levels are approximately half that of maternal blood. All 3 children are healthy. Although there was transplacental passage of ions, there was no significant effect on the child in these cases. We did not show any teratogenic effect of metal ions on the child, and this is consistent with the reported literature. PMID:22383325

  16. Outcomes of patellar resurfacing versus nonresurfacing in total knee arthroplasty: a 9-year experience based on a case series of scorpio PS knees.

    PubMed

    Epinette, Jean-Alain; Manley, Michael T

    2008-10-01

    Patellar resurfacing during total knee arthroplasty (TKA) is an actively debated issue. This prospective study addresses fundamental questions regarding whether to resurface the patella. To do this, we compared clinical results of Scorpio PS knees with and without patellar resurfacing to determine whether there was any statistically significant difference in survivorship, function, pain, and radiographic analyses. Our study failed to demonstrate any statistical difference between the 2 groups (resurfaced versus nonresurfaced) according to knee pain, walking abilities, stair climbing, range of motion, and radiologic findings, as well as cross-correlations between patellar pain and age, gender, obesity, or etiology. Our radiologic findings did not reveal any failures of bony structures facing the metallic flange. Some knee designs can thus be seen as "patella friendly." Given the significant cost of patella resurfacing and the resulting well-known complications, we continue to avoid systematic resurfacing of the patella during Scorpio TKA. PMID:18979932

  17. Nonequilibrium Ablation of Phenolic Impregnated Carbon Ablator

    NASA Technical Reports Server (NTRS)

    Milos, Frank S.; Chen, Yih K.; Gokcen, Tahir

    2012-01-01

    In previous work, an equilibrium ablation and thermal response model for Phenolic Impregnated Carbon Ablator was developed. In general, over a wide range of test conditions, model predictions compared well with arcjet data for surface recession, surface temperature, in-depth temperature at multiple thermocouples, and char depth. In this work, additional arcjet tests were conducted at stagnation conditions down to 40 W/sq cm and 1.6 kPa. The new data suggest that nonequilibrium effects become important for ablation predictions at heat flux or pressure below about 80 W/sq cm or 10 kPa, respectively. Modifications to the ablation model to account for nonequilibrium effects are investigated. Predictions of the equilibrium and nonequilibrium models are compared with the arcjet data.

  18. Surgical Ablation of Atrial Fibrillation

    PubMed Central

    Ramlawi, Basel; Abu Saleh, Walid K.

    2015-01-01

    The Cox-maze procedure for the restoration of normal sinus rhythm, initially developed by Dr. James Cox, underwent several iterations over the years. The main concept consists of creating a series of transmural lesions in the right and left atria that disrupt re-entrant circuits responsible for propagating the abnormal atrial fibrillation rhythm. The left atrial appendage is excluded as a component of the Maze procedure. For the first three iterations of the Cox- maze procedure, these lesions were performed using a surgical cut-and-sew approach that ensured transmurality. The Cox-Maze IV is the most currently accepted iteration. It achieves the same lesion set of the Cox- maze III but uses alternative energy sources to create the transmural lesions, potentially in a minimally invasive approach on the beating heart. High-frequency ultrasound, microwave, and laser energy have all been used with varying success in the past. Today, bipolar radiofrequency heat or cryotherapy cooling are the most accepted sources for creating linear lesions with consistent safety and transmurality. The robust and reliable nature of these energy delivery methods has yielded a success rate reaching 90% freedom from atrial fibrillation at 12 months. Such approaches offer a significant long-term advantage over catheter-based ablation, especially in patients having longstanding, persistent atrial fibrillation with characteristics such as dilated left atrial dimensions, poor ejection fraction, and failed catheter ablation. Based on these improved results, there currently is significant interest in developing a hybrid ablation strategy that incorporates the superior transmural robust lesions of surgical ablation, the reliable stroke prevention potential of epicardial left atrial appendage exclusion, and sophisticated mapping and confirmatory catheter-based ablation technology. Such a minimally invasive hybrid strategy for ablation may lead to the development of multidisciplinary “Afib teams

  19. Renal Ablation Update

    PubMed Central

    Khiatani, Vishal; Dixon, Robert G.

    2014-01-01

    Thermal ablative technologies have evolved considerably in the recent past and are now an important component of current clinical guidelines for the treatment of small renal masses. Both radiofrequency ablation and cryoablation have intermediate-term oncologic control that rivals surgical options, with favorable complication profiles. Studies comparing cryoablation and radiofrequency ablation show no significant difference in oncologic control or complication profile between the two modalities. Early data from small series with microwave ablation have shown similar promising results. Newer technologies including irreversible electroporation and high-intensity–focused ultrasound have theoretical advantages, but will require further research before becoming a routine part of the ablation armamentarium. The purpose of this review article is to discuss the current ablative technologies available, briefly review their mechanisms of action, discuss technical aspects of each, and provide current data supporting their use. PMID:25049445

  20. Renal ablation update.

    PubMed

    Khiatani, Vishal; Dixon, Robert G

    2014-06-01

    Thermal ablative technologies have evolved considerably in the recent past and are now an important component of current clinical guidelines for the treatment of small renal masses. Both radiofrequency ablation and cryoablation have intermediate-term oncologic control that rivals surgical options, with favorable complication profiles. Studies comparing cryoablation and radiofrequency ablation show no significant difference in oncologic control or complication profile between the two modalities. Early data from small series with microwave ablation have shown similar promising results. Newer technologies including irreversible electroporation and high-intensity-focused ultrasound have theoretical advantages, but will require further research before becoming a routine part of the ablation armamentarium. The purpose of this review article is to discuss the current ablative technologies available, briefly review their mechanisms of action, discuss technical aspects of each, and provide current data supporting their use. PMID:25049445

  1. Radiofrequency Ablation of Cancer

    PubMed Central

    Friedman, Marc; Mikityansky, Igor; Kam, Anthony; Libutti, Steven K.; Walther, McClellan M.; Neeman, Ziv; Locklin, Julia K.; Wood, Bradford J.

    2008-01-01

    Radiofrequency ablation (RFA) has been used for over 18 years for treatment of nerve-related chronic pain and cardiac arrhythmias. In the last 10 years, technical developments have increased ablation volumes in a controllable, versatile, and relatively inexpensive manner. The host of clinical applications for RFA have similarly expanded. Current RFA equipment, techniques, applications, results, complications, and research avenues for local tumor ablation are summarized. PMID:15383844

  2. Radiofrequency Ablation of Cancer

    SciTech Connect

    Friedman, Marc; Mikityansky, Igor; Kam, Anthony; Libutti, Steven K.; Walther, McClellan M.; Neeman, Ziv; Locklin, Julia K.; Wood, Bradford J.

    2004-09-15

    Radiofrequency ablation (RFA) has been used for over 18 years for treatment of nerve-related chronic pain and cardiac arrhythmias. In the last 10 years, technical developments have increased ablation volumes in a controllable, versatile, and relatively inexpensive manner. The host of clinical applications for RFA have similarly expanded. Current RFA equipment, techniques, applications, results, complications, and research avenues for local tumor ablation are summarized.

  3. Lung Ablation: Whats New?

    PubMed

    Xiong, Lillian; Dupuy, Damian E

    2016-07-01

    Lung cancer had an estimated incidence of 221,200 in 2015, making up 13% of all cancer diagnoses. Tumor ablation is an important treatment option for nonsurgical lung cancer and pulmonary metastatic patients. Radiofrequency ablation has been used for over a decade with newer modalities, microwave ablation, cryoablation, and irreversible electroporation presenting as additional and possibly improved treatment options for patients. This minimally invasive therapy is best for small primary lesions or favorably located metastatic tumors. These technologies can offer palliation and sometimes cure of thoracic malignancies. This article discusses the current available technologies and techniques available for tumor ablation. PMID:27050331

  4. Ablative Thermal Protection System Fundamentals

    NASA Technical Reports Server (NTRS)

    Beck, Robin A. S.

    2013-01-01

    This is the presentation for a short course on the fundamentals of ablative thermal protection systems. It covers the definition of ablation, description of ablative materials, how they work, how to analyze them and how to model them.

  5. Total knee replacement with and without patellar resurfacing: a prospective, randomised trial using the profix total knee system.

    PubMed

    Smith, A J; Wood, D J; Li, M-G

    2008-01-01

    We have examined the differences in clinical outcome of total knee replacement (TKR) with and without patellar resurfacing in a prospective, randomised study of 181 osteoarthritic knees in 142 patients using the Profix total knee system which has a femoral component with features considered to be anatomical and a domed patellar implant. The procedures were carried out between February 1998 and November 2002. A total of 159 TKRs in 142 patients were available for review at a mean of four years (3 to 7). The patients and the clinical evaluator were blinded in this prospective study. Evaluation was undertaken annually by an independent observer using the knee pain scale and the Knee Society clinical rating system. Specific evaluation of anterior knee pain, stair-climbing and rising from a seated to a standing position was also undertaken. No benefit was shown of TKR with patellar resurfacing over that without resurfacing with respect to any of the measured outcomes. In 22 of 73 knees (30.1%) with and 18 of 86 knees (20.9%) without patellar resurfacing there was some degree of anterior knee pain (p = 0.183). No revisions related to the patellofemoral joint were performed in either group. Only one TKR in each group underwent a re-operation related to the patellofemoral joint. A significant association between knee flexion contracture and anterior knee pain was observed in those knees with patellar resurfacing (p = 0.006). PMID:18160498

  6. Microwave Ablation of Hepatic Malignancy

    PubMed Central

    Lubner, Meghan G.; Brace, Christopher L.; Ziemlewicz, Tim J.; Hinshaw, J. Louis; Lee, Fred T.

    2013-01-01

    Microwave ablation is an extremely promising heat-based thermal ablation modality that has particular applicability in treating hepatic malignancies. Microwaves can generate very high temperatures in very short time periods, potentially leading to improved treatment efficiency and larger ablation zones. As the available technology continues to improve, microwave ablation is emerging as a valuable alternative to radiofrequency ablation in the treatment of hepatic malignancies. This article reviews the current state of microwave ablation including technical and clinical considerations. PMID:24436518

  7. Monoblock Expanded Full-thickness Graft for Resurfacing of the Burned Face in Young Patients.

    PubMed

    Allam, A M; El Khalek, A E A; Mustafa, W; Zayed, E

    2007-12-31

    It has been emphasized by many authors that to obtain better aesthetic results in a burned facial area to be resurfaced - if it extends into more than one aesthetic territory - the units involved should be combined into a single large composite unit allowing the largest possible skin graft to be used. Unfortunately, the donor site for full-thickness grafts is limited in young patients and hence tissue expansion is used. A monoblock expanded full-thickness skin graft for facial resurfacing after post-burn sequelae excision was used in 12 young patients after expansion of the superolateral aspect of the buttock. Females made up the majority of the patients (75%) and the ages ranged between 8 and 18 yr. The operating time was 3-3.5 hours, in two sessions. Post-operatively, we recorded partial graft necrosis in two cases (16.7%) and infection in one (8.3%), and some minor donor-site-related complications were reported, such as haematoma in one patient (8.3%), wound infection in one patient (8.3%), and wide scarring in two patients (16.7%). At follow-up, eight of the patients (66.7%) were satisfied with their new facial look as the mask effect of facial scarring had been overcome. With monoblock expanded full-thickness graft we were able to resurface the face in nine cases (75%). A second complementary procedure to reconstruct the eyebrows or reshape the nose was required in two cases (16.7%). We concluded that the monoblock expanded full-thickness graft was a suitable solution for limitation of the donor site in young patients, as the resulting wound could be closed primarily with a scar that could be concealed by the underwear, with lim. PMID:21991093

  8. Femoral head viability following resurfacing arthroplasty. A clinical positron emission tomography study.

    PubMed

    Ullmark, Gösta; Sundgren, Kent; Milbrink, Jan; Nilsson, Olle

    2011-01-01

    Hip resurfacing (HR) carries attendant risks of avascular necrosis (AVN) and femoral neck fracture. We used fluoride positron emission tomography (PET) scans to analyze bone metabolism 2-5 years after surgery in 35 cases. Three of the patients had been clinical failures. Using PET scans in the remaining 32 cases, 7 were found to have an area of non-viable bone in the femoral head. This was seen following both posterior and antero lateral approaches. Fluoride PET is a sensitive and useful method for evaluating bone metabolism following HR. PMID:21298626

  9. Observation of the post-inflammatory hyperpigmentation of the face laser resurfacing in China

    NASA Astrophysics Data System (ADS)

    Lin, Xiao-Hua; Wu, Hui-Zhen

    1998-11-01

    There were one hundred Chinese cases treated with face laser resurfacing. Observed the result, the post-inflammatory hyperpigmentation was found in all case. It is not any use that the cases used the 3 percent hydroquinone before the operation. Eighty-five cases were going down between two and six months after the operation. Fifteen cases continued to nine months. Five cases continued to a year. Cosmetics are possible to affect the course of inflammatory hyperpigmentation. Hyperpigmentation disappeared more quickly while using 3 percent hydroquinone cream or KA cream after the operation. And intravenous injections with vitamin C is helpful.

  10. Crater counts reveal young resurfacing in the Eastern Hellas Basin, Mars

    NASA Astrophysics Data System (ADS)

    Zuschneid, Wilhelm; van Gasselt, Stephan

    2014-05-01

    We are investigating the stratigraphy of the eastern rim region of the Hellas impact basin on Mars. As the largest well-preserved impact basin (with a diameter exceeding 2000 km and a depth of more than 8000 m below datum), it has acted as the most important depositional sink in the southern Martian hemisphere since its formation 4 Ga ago. Especially in the northeastern part of the basin, features indicating fluvial activity are widespread, and form a complex pattern of erosional and depositional units, with isolated remnants of an underlying landscape embayed by younger geologic units. The stratigraphic sequence of this region and the surface ages of the different geologic units have not been well constrained in previous work. Using data acquired by HRSC (Mars Express), CTX (Mars Reconnaissance Orbiter) and THEMIS (Mars Odyssey), we identified several small depositional areas associated with small and medium-sized fluvial channels in the vicinity of Dao and Harmakhis Valles. Several of these areas were selected for further investigation, as not all surfaces were suitable for age determination by crater size-frequency statistics. Also included in the study were several shallow basins located on the floor in the eastern part of the Hellas basin. These basins are located in the flow path of water discharged from the channels into the basin. Using crater size frequency statistics based on CTX image data for age determination, we determined a spatially extensive episode of resurfacing in the younger Martian geologic history, spanning from 400 to 600 Ma. Both the deposits associated with the channels on the basin slopes and the shallow basins on the Hellas floor are similarly affected. The large spatial spread of the crater counting areas indicates that this episode has caused resurfacing in a large region, presumably by sediment deposition. Areas with a different geologic setting did not experience resurfacing in this timespan, showing that not all surfaces were

  11. Catheter Ablation of Fascicular Ventricular Tachycardia

    PubMed Central

    Liu, Yaowu; Fang, Zhen; Yang, Bing; Kojodjojo, Pipin; Chen, Hongwu; Ju, Weizhu; Cao, Kejiang; Chen, Minglong

    2015-01-01

    Background— Fascicular ventricular tachycardia (FVT) is a common form of sustained idiopathic left ventricular tachycardia with an Asian preponderance. This study aimed to prospectively investigate long-term clinical outcomes of patients undergoing ablation of FVT and identify predictors of arrhythmia recurrence. Methods and Results— Consecutive patients undergoing FVT ablation at a single tertiary center were enrolled. Activation mapping was performed to identify the earliest presystolic Purkinje potential during FVT that was targeted by radiofrequency ablation. Follow-up with clinic visits, ECG, and Holter monitoring was performed at least every 6 months. A total of 120 consecutive patients (mean age, 29.3±12.7 years; 82% men; all patients with normal ejection fraction) were enrolled. FVT involved left posterior fascicle and left anterior fascicle in 118 and 2 subjects, respectively. VT was noninducible in 3 patients, and ablation was acutely successful in 117 patients. With a median follow-up of 55.7 months, VT of a similar ECG morphology recurred in 17 patients, and repeat procedure confirmed FVT recurrence involving the same fascicle. Shorter VT cycle length was the only significant predictor of FVT recurrence (P=0.03). Six other patients developed new-onset upper septal FVT that was successfully ablated. Conclusions— Ablation of FVT guided by activation mapping is associated with a single procedural success rate without the use of antiarrhythmic drugs of 80.3%. Arrhythmia recurrences after an initially successful ablation were caused by recurrent FVT involving the same fascicle in two thirds of patients or new onset of upper septal FVT in the remainder. PMID:26386017

  12. A Simulation of Laser Ablation During the Laser Pulse

    NASA Astrophysics Data System (ADS)

    Suzuki, Motoyuki; Ventzek, Peter L. G.; Sakai, Y.; Date, H.; Tagashira, H.; Kitamori, K.

    1996-10-01

    Charge damage considerations in plasma assisted etching are prompting the development of neutral beam sources. Already, anisotropic etching of has been demonstrated by neutral beams generated by exhausting heated ecthing gases into vacuum via a nozzle. Laser ablation of condensed etching gases may also be an attractive alternative means of generating neutral beams. Laser ablation coupled with electrical breakdown of the ablation plume may afford some degree of control over a neutral beam's dissociation fraction and ion content. Results from a Monte Carlo simulation of the laser ablation plume as it expands into vacuum at time-scales during the laser pulse will be presented. The model includes both heavy particle interactions and photochemistry. In particular, the influence of the initial particle angular distribution on the beam spread will be demonstrated as will the relationship between laser beam energy and initial ionization and dissociation fraction.

  13. How do metal ion levels change over time in hip resurfacing patients? A cohort study.

    PubMed

    Savarino, Lucia; Cadossi, Matteo; Chiarello, Eugenio; Fotia, Caterina; Greco, Michelina; Baldini, Nicola; Giannini, Sandro

    2014-01-01

    Metal-on-metal hip resurfacing (MOM-HR) is offered as an alternative to traditional hip arthroplasty for young, active adults with advanced osteoarthritis. Nevertheless, concerns remain regarding wear and corrosion of the bearing surfaces and the resulting increase in metal ion levels. We evaluated three cohorts of patients with Birmingham hip resurfacing (BHR) at an average follow-up of 2, 5, and 9 years. We asked whether there would be differences in ion levels between the cohorts and inside the gender. Nineteen patients were prospectively analyzed. The correlation with clinical-radiographic data was also performed. Chromium, cobalt, nickel, and molybdenum concentrations were measured by atomic absorption spectrophotometry. Chromium and cobalt levels demonstrated a tendency to decrease over time. Such tendency was present only in females. An inverse correlation between chromium, implant size, and Harris hip score was present at short term; it disappeared over time together with the decreased ion levels. The prospective analysis showed that, although metal ion levels remained fairly constant within each patient, there was a relatively large variation between subjects, so mean data in this scenario must be interpreted with caution. The chronic high exposure should be carefully considered during implant selection, particularly in young subjects, and a stricter monitoring is mandatory. PMID:25580456

  14. The thermal effects of lavage on 57 ox femoral heads prepared for hip resurfacing arthroplasty

    PubMed Central

    2013-01-01

    Background and purpose Previously, we have documented surface temperatures recorded by thermography great enough to cause osteonecrosis of the femoral head during hip resurfacing. We now performed an in vitro investigation with 3 questions: (1) whether water irrigation reduced bone surface temperature, (2) whether external bone temperatures were similar to core temperatures, and (3) whether blunting of the reamer affected temperature generation. Methods Using an ox-bone model, 57 femoral heads were peripherally reamed. The surface temperatures of bone were measured using a thermal camera and internal bone temperatures were measured using 2 theromocouples. We measured the effects of cooling with water at room temperature and with ice-cooled water. Progressive blunting of reamers was assessed over the 57 experiments. Results Mean and maximum temperatures generated during peripheral reaming were greater when no irrigation was used. Ice-cold saline protected femoral heads from thermal damage. External bone temperatures were much greater than internal temperatures, which were not sufficiently elevated to cause osteonecrosis regardless of lavage. Blunting of the reamer was not found to have a statistically significant effect in this study. Interpretation Cooling with ice-cooled water is recommended. Internal bone temperatures are not elevated despite the high surface temperatures reached during femoral head resurfacing. PMID:24079554

  15. Improved mechanical long-term reliability of hip resurfacing prostheses by using silicon nitride.

    PubMed

    Zhang, Wen; Titze, M; Cappi, B; Wirtz, D C; Telle, R; Fischer, H

    2010-11-01

    Although ceramic prostheses have been successfully used in conventional total hip arthroplasty (THA) for many decades, ceramic materials have not yet been applied for hip resurfacing (HR) surgeries. The objective of this study is to investigate the mechanical reliability of silicon nitride as a new ceramic material in HR prostheses. A finite element analysis (FEA) was performed to study the effects of two different designs of prostheses on the stress distribution in the femur-neck area. A metallic (cobalt-chromium-alloy) Birmingham hip resurfacing (BHR) prosthesis and our newly designed ceramic (silicon nitride) HR prosthesis were hereby compared. The stresses induced by physiologically loading the femur bone with an implant were calculated and compared with the corresponding stresses for the healthy, intact femur bone. Here, we found stress distributions in the femur bone with the implanted silicon nitride HR prosthesis which were similar to those of healthy, intact femur bone. The lifetime predictions showed that silicon nitride is indeed mechanically reliable and, thus, is ideal for HR prostheses. Moreover, we conclude that the FEA and corresponded post-processing can help us to evaluate a new ceramic material and a specific new implant design with respect to the mechanical reliability before clinical application. PMID:20725769

  16. Facial resurfacing using a high-energy, short-pulse carbon dioxide laser.

    PubMed

    Goodman, G J

    1996-08-01

    Facial skin resurfacing is now possible using short-pulse, high-energy carbon dioxide (CO2) lasers. The laser utilized in this particular paper is the Ultra-pulse CO2 laser. The Ultra-pulse laser represents the first CO2 laser able to vaporize tissue in a single pulse with the use of a large spot size. This laser utilizes the principles of selective photothermolysis. The high-power pulses are completed in less than the thermal relaxation time of skin, estimated to be less than 1 millisecond. This translates into rapid vaporization of tissue with little heat conduction to surrounding tissues. It also should allow a reproducibility of results between practitioners with set parameters not possible with previous CO2 lasers. Clinically, this laser is useful for the removal of skin lesions, and the resurfacing of areas of sun damage, wrinkles and scars. The immediate haemostasis and excellent visibility allows for precise vaporization of abnormal tissue. Rapid and pain-free wound healing is usual. The complication rate would appear to compare very favourably with dermabrasion and chemical peeling techniques. PMID:8771864

  17. Implications of the Utopia Gravity Anomaly for the Resurfacing of the Northern Plains of Mars

    NASA Technical Reports Server (NTRS)

    Banerdt, W. B.

    2004-01-01

    Whereas the surface units of the northern plain of Mars generally exhibit ages ranging from late Hesperian to Amazonian, interpretation of precise topographic measurements indicate that the age of the underlying "basement" is early Noachian, or almost as old as the southern highlands. This suggests that widespread but relatively superficial resurfacing has occurred throughout the northern plains since the end of early heavy bombardment. In this abstract I examine some of the possible implications of the subsurface structure inferred for the Utopia basin from gravity data on the nature of this resurfacing. The large, shallow, circular depression in Utopia Planitia has been identified as a huge impact basin, based on both geological evidence and detailed analysis of MOLA topography. Its diameter (approx. 3000 km) is equivalent to that of the Hellas basin, as is its inferred age (early Noachian). However, whereas Hellas is extremely deep with rough terrain and large slopes, the Utopia basin is a smooth, shallow, almost imperceptible bowl. Conversely, Utopia displays one of the largest (non-Tharsis-related) positive geoid anomalies on Mars, in contrast to a much more subdued negative anomaly over Hellas.

  18. Economically and environmentally informed policy for road resurfacing: tradeoffs between costs and greenhouse gas emissions

    NASA Astrophysics Data System (ADS)

    Reger, Darren; Madanat, Samer; Horvath, Arpad

    2014-10-01

    As road conditions worsen, users experience an increase in fuel consumption and vehicle wear and tear. This increases the costs incurred by the drivers, and also increases the amount of greenhouse gases (GHGs) that vehicles emit. Pavement condition can be improved through rehabilitation activities (resurfacing) to reduce the effects on users, but these activities also have significant cost and GHG emission impacts. The objective of pavement management is to minimize total societal (user and agency) costs. However, the environmental impacts associated with the cost-minimizing policy are not currently accounted for. We show that there exists a range of potentially optimal decisions, known as the Pareto frontier, in which it is not possible to decrease total emissions without increasing total costs and vice versa. This research explores these tradeoffs for a system of pavement segments. For a case study, a network was created from a subset of California’s highways using available traffic data. It was shown that the current resurfacing strategy used by the state’s transportation agency, Caltrans, does not fall on the Pareto frontier, meaning that significant savings in both total costs and total emissions can be achieved by switching to one of the optimal policies. The methods presented in this paper also allow the decision maker to evaluate the impact of other policies, such as reduced vehicle kilometers traveled or better construction standards.

  19. Turn over split fascial flap - a refinement for resurfacing shin defect

    PubMed Central

    Bhattacharya, Visweswar; Agrawal, Neeraj K; Chaudhuri, Gaurab R; Barooah, Partha S; SK, Tripathi; Birendra, Rana; Bhattacharya, Siddhartha; Deka, Dhruva J

    2012-01-01

    Moderate size defects of the shin of tibia are frequently encountered following trauma and infection. They may be associated with or without a fracture. Such defects require resurfacing by a flap. Many different types of flaps have been described but most of them proved to be more bulky than desired. Although these procedures cover the defects successfully the results they produce are not aesthetically appropriate. The flap looks bulkier because the native subcutaneous tissue is thin over the shin and distal leg. Hence a search for a vascularized tissue of minimal bulk for suitable resurfacing was initiated. A turnover fascial flap fulfilled the requirement. Such a flap can be made thinner by splitting its distal part into two layers while maintaining a common vascular fascial pedicle with both the layers of the fascia. This allowed a larger surface area to be covered. Such refinement is based on the following parameters (a) fresh cadaveric dissection, (b) demonstration of live microcirculation individually in the superficial and deep layers of the deep fascia and (c) intraoperative flourescein study of the split fascial flap. The technique has been used in 5 cases over the upper and middle third of the shin of tibia. The split fascial flap was turned over and inset in the defect and covered with a split skin graft. The donor site was primarily closed. The functional and aesthetic results were highly satisfactory. The follow up of 18 months proved the durability and usefulness of the flap. PMID:23071906

  20. Does Ion Release Differ Between Hip Resurfacing and Metal-on-metal THA?

    PubMed Central

    Moroni, Antonio; Cadossi, Matteo; Baldini, Nicola; Giannini, Sandro

    2008-01-01

    Modern metal-on-metal hip resurfacing was introduced as a bone-preserving method of joint reconstruction for young and active patients; however, the large diameter of the bearing surfaces is of concern for potential increased metal ion release. We hypothesized there were no differences in serum concentrations of chromium, cobalt, and molybdenum between patients who had metal-on-metal hip resurfacing (Group A; average head diameter, 48 mm; median followup, 24 months) and patients who had 28-mm metal-on-metal THA (Group B; median followup, 25 months). Serum concentrations also were compared with concentrations in healthy subjects. We identified no differences in ion levels between Groups A and B. A distinction was made according to gender. Women showed a higher chromium release in Group A whereas men had a higher cobalt release in Group B. Values obtained from Group A were higher than those of the control subjects. Our data suggest metal-on-metal bearings for THA should not be rejected because of concern regarding potential increased metal ion release; however, patients with elevated ion levels, even without loosening or toxicity, could be at higher risk and should be followed up periodically. Level of Evidence: Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence. PMID:18196364

  1. How Do Metal Ion Levels Change over Time in Hip Resurfacing Patients? A Cohort Study

    PubMed Central

    Savarino, Lucia; Cadossi, Matteo; Chiarello, Eugenio; Fotia, Caterina; Greco, Michelina; Baldini, Nicola; Giannini, Sandro

    2014-01-01

    Metal-on-metal hip resurfacing (MOM-HR) is offered as an alternative to traditional hip arthroplasty for young, active adults with advanced osteoarthritis. Nevertheless, concerns remain regarding wear and corrosion of the bearing surfaces and the resulting increase in metal ion levels. We evaluated three cohorts of patients with Birmingham hip resurfacing (BHR) at an average follow-up of 2, 5, and 9 years. We asked whether there would be differences in ion levels between the cohorts and inside the gender. Nineteen patients were prospectively analyzed. The correlation with clinical-radiographic data was also performed. Chromium, cobalt, nickel, and molybdenum concentrations were measured by atomic absorption spectrophotometry. Chromium and cobalt levels demonstrated a tendency to decrease over time. Such tendency was present only in females. An inverse correlation between chromium, implant size, and Harris hip score was present at short term; it disappeared over time together with the decreased ion levels. The prospective analysis showed that, although metal ion levels remained fairly constant within each patient, there was a relatively large variation between subjects, so mean data in this scenario must be interpreted with caution. The chronic high exposure should be carefully considered during implant selection, particularly in young subjects, and a stricter monitoring is mandatory. PMID:25580456

  2. Birmingham Hip Resurfacing--Patient reported outcomes pre and post 'Metal-on-Metal' media attention.

    PubMed

    Barke, Samuel; Malagelada, Francesc; Stafford, Giles; McMinn, Derek; Field, Richard

    2016-03-01

    We have investigated whether patient reported outcomes provided by patients with Birmingham Hip Resurfacing (BHR) changed after negative media coverage of metal-on-metal (MOM) hip replacement. We also investigated whether patients whose procedures were performed by a designer surgeon behaved differently to those performed elsewhere. 1178 consecutive BHR procedures performed between January 2002 and December 2006, by one of the designer surgeons in his private practice, were reviewed. We also reviewed 402 BHRs undertaken by two non-designer surgeons in both their NHS and private practice. 150 of the latter cohort were undertaken at an NHS hospital and 252 at an independent private hospital. All patients had annual Oxford Hip Scores (OHS) collected. We chose 2007 as pre-"media attention" and compared scores from this year against subsequent years. We found no clinically significant change in OHS between 2007 and subsequent years, at all centres. We conclude that negative media reporting does not appear to have had an impact on patients' perceived outcome after BHR. In consequence, patients who have undergone this type of hip resurfacing and show deterioration should be investigated. PMID:26984649

  3. Convergent ablator performance measurements

    SciTech Connect

    Hicks, D. G.; Spears, B. K.; Braun, D. G.; Sorce, C. M.; Celliers, P. M.; Collins, G. W.; Landen, O. L.; Olson, R. E.

    2010-10-15

    The velocity and remaining ablator mass of an imploding capsule are critical metrics for assessing the progress toward ignition of an inertially confined fusion experiment. These and other convergent ablator performance parameters have been measured using a single streaked x-ray radiograph. Traditional Abel inversion of such a radiograph is ill-posed since backlighter intensity profiles and x-ray attenuation by the ablated plasma are unknown. To address this we have developed a regularization technique which allows the ablator density profile {rho}(r) and effective backlighter profile I{sub 0}(y) at each time step to be uniquely determined subject to the constraints that {rho}(r) is localized in radius space and I{sub 0}(y) is delocalized in object space. Moments of {rho}(r) then provide the time-resolved areal density, mass, and average radius (and thus velocity) of the remaining ablator material. These results are combined in the spherical rocket model to determine the ablation pressure and mass ablation rate during the implosion. The technique has been validated on simulated radiographs of implosions at the National Ignition Facility [Miller et al., Nucl. Fusion 44, 228 (2004)] and implemented on experiments at the OMEGA laser facility [Boehly et al., Opt. Commun. 133, 495 (1997)].

  4. Tumor Ablation and Nanotechnology

    PubMed Central

    Manthe, Rachel L.; Foy, Susan P.; Krishnamurthy, Nishanth; Sharma, Blanka; Labhasetwar, Vinod

    2010-01-01

    Next to surgical resection, tumor ablation is a commonly used intervention in the treatment of solid tumors. Tumor ablation methods include thermal therapies, photodynamic therapy, and reactive oxygen species (ROS) producing agents. Thermal therapies induce tumor cell death via thermal energy and include radiofrequency, microwave, high intensity focused ultrasound, and cryoablation. Photodynamic therapy and ROS producing agents cause increased oxidative stress in tumor cells leading to apoptosis. While these therapies are safe and viable alternatives when resection of malignancies is not feasible, they do have associated limitations that prevent their widespread use in clinical applications. To improve the efficacy of these treatments, nanoparticles are being studied in combination with nonsurgical ablation regimens. In addition to better thermal effect on tumor ablation, nanoparticles can deliver anticancer therapeutics that show synergistic anti-tumor effect in the presence of heat and can also be imaged to achieve precision in therapy. Understanding the molecular mechanism of nanoparticle-mediated tumor ablation could further help engineer nanoparticles of appropriate composition and properties to synergize the ablation effect. This review aims to explore the various types of nonsurgical tumor ablation methods currently used in cancer treatment and potential improvements by nanotechnology applications. PMID:20866097

  5. Convergent ablator performance measurements

    NASA Astrophysics Data System (ADS)

    Hicks, D. G.; Spears, B. K.; Braun, D. G.; Olson, R. E.; Sorce, C. M.; Celliers, P. M.; Collins, G. W.; Landen, O. L.

    2010-10-01

    The velocity and remaining ablator mass of an imploding capsule are critical metrics for assessing the progress toward ignition of an inertially confined fusion experiment. These and other convergent ablator performance parameters have been measured using a single streaked x-ray radiograph. Traditional Abel inversion of such a radiograph is ill-posed since backlighter intensity profiles and x-ray attenuation by the ablated plasma are unknown. To address this we have developed a regularization technique which allows the ablator density profile ρ(r ) and effective backlighter profile I0(y) at each time step to be uniquely determined subject to the constraints that ρ(r ) is localized in radius space and I0(y) is delocalized in object space. Moments of ρ(r ) then provide the time-resolved areal density, mass, and average radius (and thus velocity) of the remaining ablator material. These results are combined in the spherical rocket model to determine the ablation pressure and mass ablation rate during the implosion. The technique has been validated on simulated radiographs of implosions at the National Ignition Facility [Miller et al., Nucl. Fusion 44, 228 (2004)] and implemented on experiments at the OMEGA laser facility [Boehly et al., Opt. Commun. 133, 495 (1997)].

  6. Catheter Ablation for Long-Standing Persistent Atrial Fibrillation

    PubMed Central

    Romero, Jorge; Gianni, Carola; Di Biase, Luigi; Natale, Andrea

    2015-01-01

    Atrial fibrillation (AF) is the most common sustained arrhythmia worldwide and represents a major burden to health care systems. Atrial fibrillation is associated with a 4- to 5-fold increased risk of thromboembolic stroke. The pulmonary veins have been identified as major sources of atrial triggers for AF. This is particularly true in patients with paroxysmal AF but not always the case for those with long-standing persistent AF (LSPAF), in which other locations for ectopic beats have been well recognized. Structures with foci triggering AF include the coronary sinus, the left atrial appendage (LAA), the superior vena cava, the crista terminalis, and the ligament of Marshall. More than 30 studies reporting results on radiofrequency ablation of LSPAF have been published to date. Most of these are observational studies with very different methodologies using different strategies. As a result, there has been remarkable variation in short- and long-term success, which suggests that the optimal ablation technique for LSPAF is still to be elucidated. In this review we discuss the different approaches to LSPAF catheter ablation, starting with pulmonary vein isolation (PVI) through ablation lines in different left atrial locations, the role of complex fractionated atrial electrograms, focal impulses and rotor modulation, autonomic modulation (ganglionated plexi), alcohol ablation, and the future of epicardial mapping and ablation for this arrhythmia. A stepwise ablation approach requires several key ablation techniques, such as meticulous PVI, linear ablation at the roof and mitral isthmus, electrogram-targeted ablation with particular attention to triggers in the coronary sinus and LAA, and discretionary right atrial ablation (superior vena cava, intercaval, or cavotricuspid isthmus lines). PMID:26306125

  7. Navigation Systems for Ablation

    PubMed Central

    Wood, B. J.; Kruecker, J.; Abi-Jaoudeh, N; Locklin, J.; Levy, E.; Xu, S.; Solbiati, L.; Kapoor, A.; Amalou, H.; Venkatesan, A.

    2010-01-01

    Navigation systems, devices and intra-procedural software are changing the way we practice interventional oncology. Prior to the development of precision navigation tools integrated with imaging systems, thermal ablation of hard-to-image lesions was highly dependent upon operator experience, spatial skills, and estimation of positron emission tomography-avid or arterial-phase targets. Numerous navigation systems for ablation bring the opportunity for standardization and accuracy that extends our ability to use imaging feedback during procedures. Existing systems and techniques are reviewed, and specific clinical applications for ablation are discussed to better define how these novel technologies address specific clinical needs, and fit into clinical practice. PMID:20656236

  8. Ablation of kidney tumors.

    PubMed

    Karam, Jose A; Ahrar, Kamran; Matin, Surena F

    2011-04-01

    While surgical excision remains the gold standard for curative treatment of small renal cell carcinomas, ablative therapy has a place as a minimally invasive, kidney function-preserving therapy in carefully selected patients who are poor candidates for surgery. Although laparoscopic cryoablation and percutaneous radiofrequency ablation (RFA) are commonly performed, percutaneous cryoablation and laparoscopic RFA are reportedly being performed with increasing frequency. The renal function and complication profiles following ablative therapy are favorable, while oncologic outcomes lag behind those of surgery, thus reinforcing the need for careful patient selection. PMID:21377587

  9. Moldable cork ablation material

    NASA Technical Reports Server (NTRS)

    1977-01-01

    A successful thermal ablative material was manufactured. Moldable cork sheets were tested for density, tensile strength, tensile elongation, thermal conductivity, compression set, and specific heat. A moldable cork sheet, therefore, was established as a realistic product.

  10. Cardiac ablation procedures

    MedlinePlus

    ... Accessory pathway, such as Wolff-Parkinson-White Syndrome Atrial fibrillation and atrial flutter Ventricular tachycardia ... consensus statement on catheter and surgical ablation of atrial fibrillation: ... for personnel, policy, procedures and follow-up. ...

  11. Laser ablation of concrete.

    SciTech Connect

    Savina, M.

    1998-10-05

    Laser ablation is effective both as an analytical tool and as a means of removing surface coatings. The elemental composition of surfaces can be determined by either mass spectrometry or atomic emission spectroscopy of the atomized effluent. Paint can be removed from aircraft without damage to the underlying aluminum substrate, and environmentally damaged buildings and sculptures can be restored by ablating away deposited grime. A recent application of laser ablation is the removal of radioactive contaminants from the surface and near-surface regions of concrete. We present the results of ablation tests on concrete samples using a high power pulsed Nd:YAG laser with fiber optic beam delivery. The laser-surface interaction was studied on various model systems consisting of Type I Portland cement with varying amounts of either fine silica or sand in an effort to understand the effect of substrate composition on ablation rates and mechanisms. A sample of non-contaminated concrete from a nuclear power plant was also studied. In addition, cement and concrete samples were doped with non-radioactive isotopes of elements representative of cooling waterspills, such as cesium and strontium, and analyzed by laser-resorption mass spectrometry to determine the contamination pathways. These samples were also ablated at high power to determine the efficiency with which surface contaminants are removed and captured. The results show that the neat cement matrix melts and vaporizes when little or no sand or aggregate is present. Surface flows of liquid material are readily apparent on the ablated surface and the captured aerosol takes the form of glassy beads up to a few tens of microns in diameter. The presence of sand and aggregate particles causes the material to disaggregate on ablation, with intact particles on the millimeter size scale leaving the surface. Laser resorption mass spectrometric analysis showed that cesium and potassium have similar chemical environments in the

  12. 21 CFR 888.3410 - Hip joint metal/polymer or ceramic/polymer semiconstrained resurfacing cemented prosthesis.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... use with bone cement (§ 888.3027). (b) Classification. Class III. (c) Date PMA or notice of completion of a PDP is required. A PMA or a notice of completion of a PDP is required to be filed with the Food... semiconstrained resurfacing cemented prosthesis must have an approved PMA or a declared completed PDP in...

  13. 21 CFR 888.3410 - Hip joint metal/polymer or ceramic/polymer semiconstrained resurfacing cemented prosthesis.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... use with bone cement (§ 888.3027). (b) Classification. Class III. (c) Date PMA or notice of completion of a PDP is required. A PMA or a notice of completion of a PDP is required to be filed with the Food... semiconstrained resurfacing cemented prosthesis must have an approved PMA or a declared completed PDP in...

  14. 21 CFR 888.3410 - Hip joint metal/polymer or ceramic/polymer semiconstrained resurfacing cemented prosthesis.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Hip joint metal/polymer or ceramic/polymer... Devices § 888.3410 Hip joint metal/polymer or ceramic/polymer semiconstrained resurfacing cemented prosthesis. (a) Identification. A hip joint metal/polymer or ceramic/polymer semi-constrained...

  15. 21 CFR 888.3410 - Hip joint metal/polymer or ceramic/polymer semiconstrained resurfacing cemented prosthesis.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Hip joint metal/polymer or ceramic/polymer... Devices § 888.3410 Hip joint metal/polymer or ceramic/polymer semiconstrained resurfacing cemented prosthesis. (a) Identification. A hip joint metal/polymer or ceramic/polymer semi-constrained...

  16. 21 CFR 888.3410 - Hip joint metal/polymer or ceramic/polymer semiconstrained resurfacing cemented prosthesis.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Hip joint metal/polymer or ceramic/polymer... Devices § 888.3410 Hip joint metal/polymer or ceramic/polymer semiconstrained resurfacing cemented prosthesis. (a) Identification. A hip joint metal/polymer or ceramic/polymer semi-constrained...

  17. On the lack of commensurabilities in the mean motions of the satellites of Uranus and the resurfacing of Ariel

    NASA Technical Reports Server (NTRS)

    Peale, S. J.

    1987-01-01

    The lack of commensurabilites among the mean motion of the satellites of Uranus is investigated by determining the probabilities of capture into those orbital resonances which might be encountered as the satellite orbits expand differentially from tidal torques. An alternate to this is investigated to evaluate the conditions necessary to allow sufficient tidal heating of Ariel for the observed resurfacing.

  18. Comment on 'The Global Resurfacing of Venus' by R. G. Strom, G.G. Schaber, and D.D. Dawson

    NASA Technical Reports Server (NTRS)

    Herrick, Robert R.; Izenberg, Noam; Phillips, Roger J.

    1995-01-01

    The distribution of impact craters on Venus has been the subject of a great deal of analysis since the return of Magellan data. Phillips el al. (1992) performed Monte Carlo two-dimensional (2-D) modeling of the areal distribution of craters, and the results of that exercise allowed a restricted, but still quite large, range of possible planetary resurfacing histories, including the possibility that the crater, were emplaced on a geologically inactive planet. However, the nonrandom distribution of embayed and deformed craters (Phillips el al., 1992), the hypsometric distribution of craters (Herrick and Phillips, 1994), the varied degradation states of craters (Izenberg et al., 1994), their nonrandom distribution with different geologic terrain types (Namiki and Solomon, 1994; Price et al, 1994), and three-dimensional resurfacing modeling (Bullock el al., 1993) all seem to argue against that particular possibility. In contrast, Strom el al. (1994) have collected a refined and more comprehensive data set of impact features, and they input these data into more sophisticated 2-D Monte Carlo modeling and statistical analyses of the areal distribution of craters, the hypsometric distribution of craters, and the number of embayed craters. They concluded that 'Venus experienced a global resurfacing event about 300 m.y. ago followed by a dramatic reduction of volcanism and tectonism. This global resurfacing event ended abruptly (less than 10 m.y.). The present crater population has accumulated since then and remains largely intact . . . only about 4%-6% of the planet has been volcanically resurfaced since the global event . . .' If these conclusions are well-founded, this work certainly represents a significant advancement in restricting tile number of plausible resurfacing histories for the planet. If Strom et al. (1994) are correct, it would also mean that all of the other aforementioned works are in error to various degrees, or at least represent overzealous

  19. Comment on 'The Global Resurfacing of Venus' by R. G. Strom, G.G. Schaber, and D.D. Dawson

    NASA Astrophysics Data System (ADS)

    Herrick, Robert R.; Izenberg, Noam; Phillips, Roger J.

    1995-11-01

    The distribution of impact craters on Venus has been the subject of a great deal of analysis since the return of Magellan data. Phillips el al. (1992) performed Monte Carlo two-dimensional (2-D) modeling of the areal distribution of craters, and the results of that exercise allowed a restricted, but still quite large, range of possible planetary resurfacing histories, including the possibility that the crater, were emplaced on a geologically inactive planet. However, the nonrandom distribution of embayed and deformed craters (Phillips el al., 1992), the hypsometric distribution of craters (Herrick and Phillips, 1994), the varied degradation states of craters (Izenberg et al., 1994), their nonrandom distribution with different geologic terrain types (Namiki and Solomon, 1994; Price et al, 1994), and three-dimensional resurfacing modeling (Bullock el al., 1993) all seem to argue against that particular possibility. In contrast, Strom el al. (1994) have collected a refined and more comprehensive data set of impact features, and they input these data into more sophisticated 2-D Monte Carlo modeling and statistical analyses of the areal distribution of craters, the hypsometric distribution of craters, and the number of embayed craters. They concluded that 'Venus experienced a global resurfacing event about 300 m.y. ago followed by a dramatic reduction of volcanism and tectonism. This global resurfacing event ended abruptly (less than 10 m.y.). The present crater population has accumulated since then and remains largely intact . . . only about 4%-6% of the planet has been volcanically resurfaced since the global event . . .' If these conclusions are well-founded, this work certainly represents a significant advancement in restricting tile number of plausible resurfacing histories for the planet. If Strom et al. (1994) are correct, it would also mean that all of the other aforementioned works are in error to various degrees, or at least represent overzealous

  20. Hip resurfacing after iliofemoral distraction for type IV developmental dysplasia of the hip a case report.

    PubMed

    Sambri, A; Cadossi, M; Mazzotti, A; Faldini, C; Giannini, S

    2015-01-01

    Osteoarthritis secondary to developmental dysplasia of the hip is a surgical challenge because of the modified anatomy of the acetabulum which is deficient in its shape with poor bone quality, torsional deformities of the femur and the altered morphology of femoral head. Particularly in Crowe type III and IV, additional surgical challenges are present, such as limb-length discrepancy and adductor muscle contractures. This is a bilateral hip dysplasia case where bilateral hip replacement was indicated, on the left side with a resurfacing one and on the other side a two stage procedure using a iliofemoral external fixator to restore equal leg length with a lower risk of complications. This case report shows both the negative clinical outcome of the left and the excellent one of the right hip where the dysplasia was much more severe. Patient selection and implant positioning are crucial in determining long-term results. PMID:27218252

  1. Skin resurfacing in a circumferential full thickness burn to the penis: lessons learnt

    PubMed Central

    Jabir, Shehab; Frew, Quentin; Thompson, Richard; Dziewulski, Peter

    2013-01-01

    A circumferential full-thickness burn to the penis is a rarely encountered injury. However, when it does occur, it proves a management challenge to the plastic and burns surgeon in terms of reconstruction. This is due to the need of not only regaining adequate function of the organ, but also because of the need for a pleasing aesthetic outcome. Split-skin grafts have been utilised successfully to resurface full thickness burns of the penis and have given good results. Yet the success of split-skin grafts, especially those applied to an anatomically challenging region of the body such as the penis, depends on a number of carefully thought-out steps. We discuss the case of a circumferential full-thickness burn to the penis which was treated with split-skin grafting and highlight important pitfalls that the plastic and burns surgeon need to be aware of to ensure a successful outcome. PMID:23946511

  2. Venus impact craters: Implications for atmospheric and resurfacing processes from Magellan observations

    NASA Technical Reports Server (NTRS)

    Phillips, Roger J.

    1991-01-01

    Observations of impact craters on Venus by Magellan yield important insights into: (1) atmospheric effects on the formation of impact craters and their attendant ejecta deposits and (2) the resurfacing history of the planet. Most craters smaller than 15 km are classified as irregular; they possess irregularly shaped rims, and multiple hummocky floors. The irregular nature of these craters is interpreted to be the consequence of breakup and dispersion of incoming meteoroids by the dense atmosphere. Two major ejecta facies of venusian impact craters are hummocky ejecta and outer ejecta. A number of craters documented in the Magellan images possess often non-radial, flow-like ejecta indicative of a low viscosity materials. Approximately half of the impact craters observed with the Magellan radar are partially or wholly surrounded by areas with low radar backscatter cross sections.

  3. Ablative therapies for renal tumors

    PubMed Central

    Ramanathan, Rajan; Leveillee, Raymond J.

    2010-01-01

    Owing to an increased use of diagnostic imaging for evaluating patients with other abdominal conditions, incidentally discovered kidney masses now account for a majority of renal tumors. Renal ablative therapy is assuming a more important role in patients with borderline renal impairment. Renal ablation uses heat or cold to bring about cell death. Radiofrequency ablation and cryoablation are two such procedures, and 5-year results are now emerging from both modalities. Renal biopsy at the time of ablation is extremely important in order to establish tissue diagnosis. Real-time temperature monitoring at the time of radiofrequency ablation is very useful to ensure adequacy of ablation. PMID:21789083

  4. Resurfacing hip arthroplasty in neuromuscular hip disorders – A retrospective case series

    PubMed Central

    Tudor, Francois; Ariamanesh, Amir; Potty, Anish; Hashemi-Nejad, Aresh

    2013-01-01

    Background Management of the degenerate hip in patients with neuromuscular conditions should be aimed at improving quality of life and ease of nursing care. Arthroplasty poses a significant challenge with predisposition to dislocation and loosening due to anatomical abnormalities, soft tissue contractures and impaired muscle tone. Methods We present a series of 11 hips (9 patients) following total hip resurfacing arthroplasty for painful osteoarthritis in patients with differing neuromuscular conditions. Patients were assessed clinically and radiographically and also for satisfaction of their carers due to improved ability to provide nursing care. Mean patient age was 33.1 years (range 13–49 years) with mean follow up at publication 63.7 months (41–89 months). All patients were operated by a single surgeon (AHN) and received the required post operative care and physiotherapy. Soft tissue releases were performed when necessary. All hips were assessed clinically and radiographically at 6 weeks and 6 months and 1 year post-operatively. Six month follow-up also included a questionnaire with scoring of care-provider satisfaction. Results Ten hips had good clinical results with improvement in pain and function and radiologically showed no signs of loosening. One hip required revision to proximal femoral excision due to dislocation and loose acetabular component with severe pain. None of the other hips dislocated. Analysis of care provider satisfaction assessing ability to provide personal care, positioning and transferring, comfort, interaction and communication scored excellent to good in 10 patients and satisfactory in one. Conclusion We believe hip resurfacing arthroplasty to be a viable option in the treatment of the complex problem of osteoarthritis in the hips of patients with neuromuscular disease. The improved biomechanics confer greater stability when compared to conventional total hip arthroplasty. Although technically demanding, a successful result has

  5. 100-μsec pulsed CO2 laser resurfacing of lower eyelids: erythema and rhytides reduction

    NASA Astrophysics Data System (ADS)

    Bell, Thomas; Harris, David M.; Schachter, Daniel; Burkart, John

    1997-05-01

    Lower eyelid skin is very thin with a low density of adnexal structures. Attempts to remove rhytides and improve surface appearance with chemical peels and dermabrasion have been disappointing. Laser resurfacing offers a new modality that may improve the outcome. We evaluated a very short duration (100 microsecond(s) ec) pulsed carbon-dioxide laser (Tru-PulseTM) in terms of healing time (duration of erythema) and efficacy (wrinkle reduction). Female patients aged 35 - 75 received laser resurfacing in a variety of cosmetic zones but only data from lower lids are reported here. Dosimetry varied from total fluences of 5 to 20 J/cm2 (9 mm2 spot, 250 - 500 mJ pulse, 1 to 4 passes). Patients followed a strict regime of post-op wound care. Pre-treatment and follow-up photographs were taken in a studio with constant photographic parameters. Projected 35 mm slides were evaluated side-by-side for clinical improvement and presence of erythema. Within the first 4 days post-op all (100%) lower eyelids exhibited erythema and swelling, at 7 days: 71%, 12 days: 60%, 3 weeks: 25%, and one (1) month or longer 7%. In our sample the longest duration of post-op lower lid erythema lasted 5 weeks. Most patients experienced 70 -80% wrinkle reduction with a range of 0 - 100%. Regression analysis was used to evaluate the relationships between percent wrinkle reduction and the treatment, demographic, and evaluation variables. There was a significant trend for wrinkles to improve over the 3 to 9 month evaluation period. Older patients improved slightly more than younger patients. There was no relationship between total energy density and wrinkle reduction.

  6. Atrial fibrillation ablation.

    PubMed

    Pappone, Carlo; Santinelli, Vincenzo

    2012-06-01

    Atrial fibrillation is the commonest cardiac arrhythmia, with significant morbidity related to symptoms, heart failure, and thromboembolism, which is associated with excess mortality. Over the past 10 years, many centers worldwide have reported high success rates and few complications after a single ablation procedure in patients with paroxysmal atrial fibrillation. Recent studies indicate a short-term and long-term superiority of catheter ablation as compared with conventional antiarrhythmic drug therapy in terms of arrhythmia recurrence, quality of life, and arrhythmia progression. As a result, catheter ablation is evolving to a front-line therapy in many patients with atrial fibrillation. However, in patients with persistent long-standing atrial fibrillation catheter ablation strategy is more complex and time-consuming, frequently requiring repeat procedures to achieve success rates as high as in paroxysmal atrial fibrillation. In the near future, however, with growing experience and evolving technology, catheter ablation of atrial fibrillation may be extended also to patients with long-standing atrial fibrillation. PMID:22541284

  7. Infrared laser bone ablation

    SciTech Connect

    Nuss, R.C.; Fabian, R.L.; Sarkar, R.; Puliafito, C.A.

    1988-01-01

    The bone ablation characteristics of five infrared lasers, including three pulsed lasers (Nd:YAG, lambda = 1064 micron; Hol:YSGG, lambda = 2.10 micron; and Erb:YAG, lambda = 2.94 micron) and two continuous-wave lasers (Nd:YAG, lambda = 1.064 micron; and CO/sub 2/, lambda = 10.6 micron), were studied. All laser ablations were performed in vitro, using moist, freshly dissected calvarium of guinea pig skulls. Quantitative etch rates of the three pulsed lasers were calculated. Light microscopy of histologic sections of ablated bone revealed a zone of tissue damage of 10 to 15 micron adjacent to the lesion edge in the case of the pulsed Nd:YAG and the Erb:YAG lasers, from 20 to 90 micron zone of tissue damage for bone ablated by the Hol:YSGG laser, and 60 to 135 micron zone of tissue damage in the case of the two continuous-wave lasers. Possible mechanisms of bone ablation and tissue damage are discussed.

  8. Hydrodynamic Efficiency of Ablation Propulsion with Pulsed Ion Beam

    SciTech Connect

    Buttapeng, Chainarong; Yazawa, Masaru; Harada, Nobuhiro; Suematsu, Hisayuki; Jiang Weihua; Yatsui, Kiyoshi

    2006-05-02

    This paper presents the hydrodynamic efficiency of ablation plasma produced by pulsed ion beam on the basis of the ion beam-target interaction. We used a one-dimensional hydrodynamic fluid compressible to study the physics involved namely an ablation acceleration behavior and analyzed it as a rocketlike model in order to investigate its hydrodynamic variables for propulsion applications. These variables were estimated by the concept of ablation driven implosion in terms of ablated mass fraction, implosion efficiency, and hydrodynamic energy conversion. Herein, the energy conversion efficiency of 17.5% was achieved. In addition, the results show maximum energy efficiency of the ablation process (ablation efficiency) of 67% meaning the efficiency with which pulsed ion beam energy-ablation plasma conversion. The effects of ion beam energy deposition depth to hydrodynamic efficiency were briefly discussed. Further, an evaluation of propulsive force with high specific impulse of 4000s, total impulse of 34mN and momentum to energy ratio in the range of {mu}N/W was also analyzed.

  9. Laser ablation in analytical chemistry-a review.

    PubMed

    Russo, Richard E; Mao, Xianglei; Liu, Haichen; Gonzalez, Jhanis; Mao, Samuel S

    2002-05-24

    Laser ablation is becoming a dominant technology for direct solid sampling in analytical chemistry. Laser ablation refers to the process in which an intense burst of energy delivered by a short laser pulse is used to sample (remove a portion of) a material. The advantages of laser ablation chemical analysis include direct characterization of solids, no chemical procedures for dissolution, reduced risk of contamination or sample loss, analysis of very small samples not separable for solution analysis, and determination of spatial distributions of elemental composition. This review describes recent research to understand and utilize laser ablation for direct solid sampling, with emphasis on sample introduction to an inductively coupled plasma (ICP). Current research related to contemporary experimental systems, calibration and optimization, and fractionation is discussed, with a summary of applications in several areas. PMID:18968642

  10. Transient Ablation of Teflon Hemispheres

    NASA Technical Reports Server (NTRS)

    Arai, Norio; Karashima, Kei-ichi; Sato, Kiyoshi

    1997-01-01

    For high-speed entry of space vehicles into atmospheric environments, ablation is a practical method for alleviating severe aerodynamic heating. Several studies have been undertaken on steady or quasi-steady ablation. However, ablation is a very complicated phenomenon in which a nonequilibrium chemical process is associated with an aerodynamic process that involves changes in body shape with time. Therefore, it seems realistic to consider that ablation is an unsteady phenomenon. In the design of an ablative heat-shield system, since the ultimate purpose of the heat shield is to keep the internal temperature of the space vehicle at a safe level during entry, the transient heat conduction characteristics of the ablator may be critical in the selection of the material and its thickness. This note presents an experimental study of transient ablation of Teflon, with particular emphasis on the change in body shape, the instantaneous internal temperature distribution, and the effect of thermal expansion on ablation rate.

  11. Tumour ablation: technical aspects

    PubMed Central

    Bodner, Gerd; Bale, Reto

    2009-01-01

    Abstract Image-guided percutaneous radiofrequency ablation (RFA) is a minimally invasive, relatively low-risk procedure for tumour treatment. Local recurrence and survival rates depend on the rate of complete ablation of the entire tumour including a sufficient margin of surrounding healthy tissue. Currently a variety of different RFA devices are available. The interventionalist must be able to predict the configuration and extent of the resulting ablation necrosis. Accurate planning and execution of RFA according to the size and geometry of the tumour is essential. In order to minimize complications, individualized treatment strategies may be necessary for tumours close to vital structures. This review examines the state-of-the art of different device technologies, approaches, and treatment strategies for percutaneous RFA of liver tumours. PMID:19965296

  12. Advanced Ablative TPS

    NASA Technical Reports Server (NTRS)

    Gasch, Matthew J.

    2011-01-01

    Early NASA missions (Gemini, Apollo, Mars Viking) employed new ablative TPS that were tailored for the entry environment. After 40 years, heritage ablative TPS materials using Viking or Pathfinder era materials are at or near their performance limits and will be inadequate for future exploration missions. Significant advances in TPS materials technology are needed in order to enable any subsequent human exploration missions beyond Low Earth Orbit. This poster summarizes some recent progress at NASA in developing families of advanced rigid/conformable and flexible ablators that could potentially be used for thermal protection in planetary entry missions. In particular the effort focuses technologies required to land heavy (approx.40 metric ton) masses on Mars to facilitate future exploration plans.

  13. The digital global geologic map of Mars: chronostratigraphic ages, topographic and crater morphologic characteristics, and updated resurfacing history

    USGS Publications Warehouse

    Tanaka, K.L.; Robbins, S.J.; Fortezzo, C.M.; Skinner, J.A., Jr.; Hare, T.M.

    2014-01-01

    A new global geologic map of Mars has been completed in a digital, geographic information system (GIS) format using geospatially controlled altimetry and image data sets. The map reconstructs the geologic history of Mars, which includes many new findings collated in the quarter century since the previous, Viking-based global maps were published, as well as other discoveries that were made during the course of the mapping using new data sets. The technical approach enabled consistent and regulated mapping that is appropriate not only for the map's 1:20,000,000 scale but also for its widespread use by diverse audiences. Each geologic unit outcrop includes basic attributes regarding identity, location, area, crater densities, and chronostratigraphic age. In turn, units are grouped by geographic and lithologic types, which provide synoptic global views of material ages and resurfacing character for the Noachian, Hesperian, and Amazonian periods. As a consequence of more precise and better quality topographic and morphologic data and more complete crater-density dating, our statistical comparisons identify significant refinements for how Martian geologic terrains are characterized. Unit groups show trends in mean elevation and slope that relate to geographic occurrence and geologic origin. In comparison with the previous global geologic map series based on Viking data, the new mapping consists of half the number of units due to simpler, more conservative and globally based approaches to discriminating units. In particular, Noachian highland surfaces overall have high percentages of their areas now dated as an epoch older than in the Viking mapping. Minimally eroded (i.e., pristine) impact craters ≥3 km in diameter occur in greater proportion on Hesperian surfaces. This observation contrasts with a deficit of similarly sized craters on heavily cratered and otherwise degraded Noachian terrain as well as on young Amazonian surfaces. We interpret these as reflecting the

  14. The digital global geologic map of Mars: Chronostratigraphic ages, topographic and crater morphologic characteristics, and updated resurfacing history

    NASA Astrophysics Data System (ADS)

    Tanaka, K. L.; Robbins, S. J.; Fortezzo, C. M.; Skinner, J. A.; Hare, T. M.

    2014-05-01

    A new global geologic map of Mars has been completed in a digital, geographic information system (GIS) format using geospatially controlled altimetry and image data sets. The map reconstructs the geologic history of Mars, which includes many new findings collated in the quarter century since the previous, Viking-based global maps were published, as well as other discoveries that were made during the course of the mapping using new data sets. The technical approach enabled consistent and regulated mapping that is appropriate not only for the map's 1:20,000,000 scale but also for its widespread use by diverse audiences. Each geologic unit outcrop includes basic attributes regarding identity, location, area, crater densities, and chronostratigraphic age. In turn, units are grouped by geographic and lithologic types, which provide synoptic global views of material ages and resurfacing character for the Noachian, Hesperian, and Amazonian periods. As a consequence of more precise and better quality topographic and morphologic data and more complete crater-density dating, our statistical comparisons identify significant refinements for how Martian geologic terrains are characterized. Unit groups show trends in mean elevation and slope that relate to geographic occurrence and geologic origin. In comparison with the previous global geologic map series based on Viking data, the new mapping consists of half the number of units due to simpler, more conservative and globally based approaches to discriminating units. In particular, Noachian highland surfaces overall have high percentages of their areas now dated as an epoch older than in the Viking mapping. Minimally eroded (i.e., pristine) impact craters ≥3 km in diameter occur in greater proportion on Hesperian surfaces. This observation contrasts with a deficit of similarly sized craters on heavily cratered and otherwise degraded Noachian terrain as well as on young Amazonian surfaces. We interpret these as reflecting the

  15. Shuttle subscale ablative nozzle tests

    NASA Technical Reports Server (NTRS)

    Powers, L. B.; Bailey, R. L.

    1980-01-01

    Recent subscale nozzle tests have identified new and promising carbon phenolic nozzle ablatives which utilize staple rayon, PAN, and pitch based carbon cloth. A 4-inch throat diameter submerged test nozzle designed for the 48-inch Jet Propulsion Laboratory char motor was used to evaluate five different designs incorporating 20 candidate ablatives. Test results indicate that several pitch and PAN-based carbon phenolic ablatives can provide erosion and char performance equivalent or superior to the present continuous rayon-based SRM ablative.

  16. Ablative thermal protection systems

    NASA Technical Reports Server (NTRS)

    Vaniman, J.; Fisher, R.; Wojciechowski, C.; Dean, W.

    1983-01-01

    The procedures used to establish the TPS (thermal protection system) design of the SRB (solid rocket booster) element of the Space Shuttle vehicle are discussed. A final evaluation of the adequacy of this design will be made from data obtained from the first five Shuttle flights. Temperature sensors installed at selected locations on the SRB structure covered by the TPS give information as a function of time throughout the flight. Anomalies are to be investigated and computer design thermal models adjusted if required. In addition, the actual TPS ablator material loss is to be measured after each flight and compared with analytically determined losses. The analytical methods of predicting ablator performance are surveyed.

  17. Is Mapping of Complex Fractionated Electrograms Obsolete?

    PubMed

    Sohal, Manav; Choudhury, Rajin; Taghji, Philippe; Louw, Ruan; Wolf, Michael; Fedida, Joel; Vandekerckhove, Yves; Tavernier, Rene; Duytschaever, Mattias; Knecht, Sébastien

    2015-08-01

    Atrial fibrillation is the most common clinically encountered arrhythmia and catheter ablation has emerged as a viable treatment option in drug-refractory cases. Pulmonary vein isolation is widely regarded as the cornerstone for successful outcomes in paroxysmal AF given that the pulmonary veins are a frequent source of AF triggering. Ablation strategies for persistent AF are less well defined. Mapping and ablation of complex fractionated electrograms (CFAEs) is one strategy that has been proposed as a means of modifying the atrial substrate thought to be critical to the perpetuation of AF. Results of clinical studies have proved conflicting and there are now strong data to suggest that pulmonary vein isolation alone is associated with outcomes comparable to those of pulmonary vein isolation plus CFAE ablation. Several studies have demonstrated that the majority of CFAEs are passive phenomena and therefore not critical to the perpetuation of AF. Conventional mapping technologies (using a bipolar or circular mapping catheter) lack the spatiotemporal resolution to identify mechanisms of AF persistence. The development of wide-field mapping techniques allows simultaneous acquisition of activation data over large areas. This strategy has the potential to better identify regions critical to AF perpetuation, and preliminary data suggest that ablation outcomes are improved when guided by these techniques. While mapping and ablation of all CFAEs is almost certainly obsolete, better identification of regions responsible for AF persistence has the potential to improve outcomes in ablation of persistent AF. PMID:26835111

  18. A Randomized controlled trial comparing patellar retention versus patellar resurfacing in primary total knee arthroplasty: 5–10 year follow-up

    PubMed Central

    2012-01-01

    Background The primary purpose of this randomized controlled trial (RCT) was to compare knee-specific outcomes (stiffness, pain, function) between patellar retention and resurfacing up to 10 years after primary total knee arthroplasty (TKA). Secondarily, we compared re-operation rates. Methods 38 subjects with non-inflammatory arthritis were randomized at primary TKA surgery to receive patellar resurfacing (n = 21; Resurfaced group) or to retain their native patella (n = 17; Non-resurfaced group). Evaluations were performed preoperatively, one, five and 10 years postoperatively by an evaluator who was blinded to group allocation. Self-reported knee-specific stiffness, pain and function, the primary outcomes, were measured by the Western Ontario McMaster Osteoarthritis Index (WOMAC). Revision rate was determined at each evaluation and through hospital record review. Results 30 (88%) and 23 (72%) of available subjects completed the five and 10-year review respectively. Knee-specific scores continued to improve for both groups over the 10-years, despite diminishing overall health with no significant group differences seen. All revisions occurred within five years of surgery (three Non-resurfaced subjects; one Resurfaced subject) (p = 0.31). Two revisions in the Non-resurfaced group were due to persistent anterior knee pain. Conclusions We found no differences in knee-specific results between groups at 5–10 years postoperatively. The Non-resurfaced group had two revisions due to anterior knee pain similar to rates reported in other studies. Knee-specific results provide useful postoperative information and should be used in future studies comparing patellar management strategies. ClinicalTrials.gov identifier NCT01500252 PMID:22676495

  19. Monte Carlo models of the interaction between impact cratering and volcanic resurfacing on Venus: The effect of the Beta-Atla-Themis anomaly

    NASA Astrophysics Data System (ADS)

    Romeo, I.

    2013-10-01

    Detailed Monte Carlo models of the interaction of impact cratering and volcanic resurfacing, which included the Beta-Atla-Themis (BAT) volcanic concentration, were used to test different planetary resurfacing histories. The results were compared with: (1) the randomness of the spatial distribution of craters, (2) the number of modified craters, (3) the number of dark-floored craters due to volcanic flooding, (4) the frequency-area distribution of volcanic units, (5) the frequency-size distribution of craters and modified craters, and (6) the spatial distribution of craters and modified craters with respect to the BAT anomaly. Two catastrophic and two equilibrium resurfacing models were tested. The two catastrophic models consisted of one with a drastic decay and the other with a moderate decay of volcanic activity following the catastrophic event. The two equilibrium models consisted of one with a gradual decay of volcanic activity at the end of the model and the other with a magmatic event followed by a gradual decay of volcanic activity. Both equilibrium models and the catastrophic model with moderate decay fail to reproduce the small reduction of the crater density in the BAT area. The model that best fits all the observations is a global catastrophic resurfacing event followed by a drastic decay of volcanic activity. Thus, a Venus global catastrophic resurfacing event erasing all previous craters with little post-resurfacing volcanism is supported by this study.

  20. Is Electrocautery of Patella Useful in Patella Non-Resurfacing Total Knee Arthroplasty?: A Prospective Randomized Controlled Study.

    PubMed

    Kwon, Sae Kwang; Nguku, Levis; Han, Chang Dong; Koh, Yong-Gon; Kim, Dong-Wook; Park, Kwan Kyu

    2015-12-01

    There is controversy over the need for electrocauterization of the patella in non-resurfacing total knee arthroplasty (TKA). We investigated whether this procedure is beneficial through a prospective randomized controlled trial. Fifty patients who underwent electrocautery were compared with 50 patients who did not undergo this procedure. We determined cartilage status, preoperative and postoperative American Knee Society (AKS) score, the Western Ontario and McMaster Universities score (WOMAC) and the Patellofemoral (PF) scores for a minimum of 5 years. The two groups did not differ significantly in demographics, intraoperative cartilage status, or preoperative or postoperative outcomes. No complications were detected in either group. We found no benefits of electrocautery of the patella in patellar non-resurfacing TKA up to 5 years. PMID:26100474

  1. Therapeutic stimulation versus ablation.

    PubMed

    Hariz, Marwan I; Hariz, Gun-Marie

    2013-01-01

    The renaissance of functional stereotactic neurosurgery was pioneered in the mid 1980s by Laitinen's introduction of Leksell's posteroventral pallidotomy for Parkinson´s disease (PD). This ablative procedure experienced a worldwide spread in the 1990s, owing to its excellent effect on dyskinesias and other symptoms of post-l-dopa PD. Modern deep brain stimulation (DBS), pioneered by Benabid and Pollak in 1987 for the treatment of tremor, first became popular when it was applied to the subthalamic nucleus (STN) in the mid 1990s, where it demonstrated a striking effect on all cardinal symptoms of advanced PD, and permitted reduced dosages of medication. DBS, as a nondestructive, adaptable, and reversible procedure that is proving safe in bilateral surgery on basal ganglia, has great appeal to clinicians and patients alike, despite the fact that it is expensive, laborious, and relies on very strict patient selection criteria, especially for STN DBS. Psychiatric surgery has experienced the same phenomenon, with DBS supplanting completely stereotactic ablative procedures. This chapter discusses the pros and cons of ablation versus stimulation and investigates the reasons why DBS has overshadowed proven efficient ablative procedures such as pallidotomy for PD, and capsulotomy and cingulotomy for obsessive-compulsive disorder and depression. PMID:24112885

  2. Advanced Rigid Ablative TPS

    NASA Technical Reports Server (NTRS)

    Gasch, Matthew J.

    2011-01-01

    NASA Exploration Systems Mission Directorate s (ESMD) Entry, Descent, and Landing (EDL) Technology Development Project (TDP) and the NASA Aeronautics Research Mission Directorate s (ARMD) Hypersonics Project are developing new advanced rigid ablators in an effort to substantially increase reliability, decrease mass, and reduce life cycle cost of rigid aeroshell-based entry systems for multiple missions. Advanced Rigid Ablators combine ablation resistant top layers capable of high heat flux entry and enable high-speed EDL with insulating mass-efficient bottom that, insulate the structure and lower the areal weight. These materials may benefit Commercial Orbital Transportation Services (COTS) vendors and may potentially enable new NASA missions for higher velocity returns (e.g. asteroid, Mars). The materials have been thermally tested to 400-450 W/sq cm at the Laser Hardened Materials Evaluation Lab (LHMEL), Hypersonics Materials Evaluation Test System (HyMETS) and in arcjet facilities. Tested materials exhibit much lower backface temperatures and reduced recession over the baseline materials (PICA). Although the EDL project is ending in FY11, NASA in-house development of advanced ablators will continue with a focus on varying resin systems and fiber/resin interactions.

  3. New Ablation Technologies and Techniques

    PubMed Central

    Berte, Benjamin; Yamashita, Seigo; Derval, Nicolas; Denis, Arnaud; Shah, Ashok; Amraoui, Sana; Hocini, Meleze; Haissaguerre, Michel; Jais, Pierre; Sacher, Frederic

    2014-01-01

    Catheter ablation is an established treatment strategy for a range of different cardiac arrhythmias. Over the past decade two major areas of expansion have been ablation of atrial fibrillation (AF) and ventricular tachycardia (VT) in the context of structurally abnormal hearts. In parallel with the expanding role of catheter ablation for AF and VT, multiple novel technologies have been developed which aim to increase safety and procedural success. Areas of development include novel catheter designs, novel navigation technologies and higher resolution imaging techniques. The aim of the present review is to provide an overview of novel developments in AF ablation and VT ablation in patients with of structural cardiac diseases. PMID:26835075

  4. New Ablation Technologies and Techniques.

    PubMed

    Mahida, Saagar; Berte, Benjamin; Yamashita, Seigo; Derval, Nicolas; Denis, Arnaud; Shah, Ashok; Amraoui, Sana; Hocini, Meleze; Haissaguerre, Michel; Jais, Pierre; Sacher, Frederic

    2014-08-01

    Catheter ablation is an established treatment strategy for a range of different cardiac arrhythmias. Over the past decade two major areas of expansion have been ablation of atrial fibrillation (AF) and ventricular tachycardia (VT) in the context of structurally abnormal hearts. In parallel with the expanding role of catheter ablation for AF and VT, multiple novel technologies have been developed which aim to increase safety and procedural success. Areas of development include novel catheter designs, novel navigation technologies and higher resolution imaging techniques. The aim of the present review is to provide an overview of novel developments in AF ablation and VT ablation in patients with of structural cardiac diseases. PMID:26835075

  5. Survivorship of standard versus modified posterior surgical approaches in metal-on-metal hip resurfacing

    PubMed Central

    M. Takamura, K.; Maher, P.; Nath, T.; Su, E. P.

    2014-01-01

    Objectives Metal-on-metal hip resurfacing (MOMHR) is available as an alternative option for younger, more active patients. There are failure modes that are unique to MOMHR, which include loosening of the femoral head and fractures of the femoral neck. Previous studies have speculated that changes in the vascularity of the femoral head may contribute to these failure modes. This study compares the survivorship between the standard posterior approach (SPA) and modified posterior approach (MPA) in MOMHR. Methods A retrospective clinical outcomes study was performed examining 351 hips (279 male, 72 female) replaced with Birmingham Hip Resurfacing (BHR, Smith and Nephew, Memphis, Tennessee) in 313 patients with a pre-operative diagnosis of osteoarthritis. The mean follow-up period for the SPA group was 2.8 years (0.1 to 6.1) and for the MPA, 2.2 years (0.03 to 5.2); this difference in follow-up period was statistically significant (p < 0.01). Survival analysis was completed using the Kaplan–Meier method. Results At four years, the Kaplan–Meier survival curve for the SPA was 97.2% and 99.4% for the MPA; this was statistically significant (log-rank; p = 0.036). There were eight failures in the SPA and two in the MPA. There was a 3.5% incidence of femoral head collapse or loosening in the SPA and 0.4% in the MPA, which represented a significant difference (p = 0.041). There was a 1.7% incidence of fractures of the femoral neck in the SPA and none in the MPA (p = 0.108). Conclusion This study found a significant difference in survivorship at four years between the SPA and the MPA (p = 0.036). The clinical outcomes of this study suggest that preserving the vascularity of the femoral neck by using the MPA results in fewer vascular-related failures in MOMHRs. Cite this article: Bone Joint Res 2014;3:150–4 PMID:24842931

  6. Three-dimensional electroanatomic mapping systems in catheter ablation of atrial fibrillation.

    PubMed

    Lo, Li-Wei; Chen, Shih-Ann

    2010-01-01

    Atrial fibrillation (AF) is the most common tachyarrhythmia, with a prevalence of 5% in people over the age of 65. Catheter ablation of AF has emerged as an important management choice for drug-refractory symptomatic paroxysmal or persistent AF. Three-dimensional (3D) electroanatomic mapping systems were introduced into catheter ablation of AF more than a decade ago. The 3D tool has the benefit of reducing the radiation exposure time, as well as voltage and fractionation mapping in order to identify the critical substrate during the ablation, prevent the formation of gaps, guide the ablation of post-ablation atrial tachycardia or flutter, and integrate images to improve the safety and long-term success rate. The 3D systems successfully enable safe and tailored radiofrequency ablation of AF in individual patients. (Circ J 2010; 74: 18 - 23). PMID:19920357

  7. Ablation, Thermal Response, and Chemistry Program for Analysis of Thermal Protection Systems

    NASA Technical Reports Server (NTRS)

    Milos, Frank S.; Chen, Yih-Kanq

    2010-01-01

    In previous work, the authors documented the Multicomponent Ablation Thermochemistry (MAT) and Fully Implicit Ablation and Thermal response (FIAT) programs. In this work, key features from MAT and FIAT were combined to create the new Fully Implicit Ablation, Thermal response, and Chemistry (FIATC) program. FIATC is fully compatible with FIAT (version 2.5) but has expanded capabilities to compute the multispecies surface chemistry and ablation rate as part of the surface energy balance. This new methodology eliminates B' tables, provides blown species fractions as a function of time, and enables calculations that would otherwise be impractical (e.g. 4+ dimensional tables) such as pyrolysis and ablation with kinetic rates or unequal diffusion coefficients. Equations and solution procedures are presented, then representative calculations of equilibrium and finite-rate ablation in flight and ground-test environments are discussed.

  8. Percutaneous Ablation of Adrenal Tumors

    PubMed Central

    Venkatesan, Aradhana M.; Locklin, Julia; Dupuy, Damian E.; Wood, Bradford J.

    2010-01-01

    Adrenal tumors comprise a broad spectrum of benign and malignant neoplasms, and include functional adrenal adenomas, pheochromocytomas, primary adrenocortical carcinoma and adrenal metastases. Percutaneous ablative approaches that have been described and used in the treatment of adrenal tumors include percutaneous radiofrequency ablation (RFA), cryoablation, microwave ablation and chemical ablation. Local tumor ablation in the adrenal gland presents unique challenges, secondary to the adrenal gland’s unique anatomic and physiologic features. The results of clinical series employing percutaneous ablative techniques in the treatment of adrenal tumors are reviewed in this article. Clinical and technical considerations unique to ablation in the adrenal gland are presented, including approaches commonly used in our practices, and risks and potential complications are discussed. PMID:20540918

  9. Evaluation of the analytical capability of NIR femtosecond laser ablation-inductively coupled plasma mass spectrometry.

    PubMed

    Hirata, Takafumi; Kon, Yoshiaki

    2008-03-01

    A laser ablation-inductively coupled plasma-mass spectrometric (LA-ICPMS) technique utilizing a titanium-sapphire (TiS) femtosecond laser (fs-laser) has been developed for elemental and isotopic analysis. The signal intensity profile, depth of the ablation pit and level of elemental fractionation were investigated in order to evaluate the analytical capability of the present fs-laser ablation-ICPMS technique. The signal intensity profile of (57)Fe, obtained from iron sulfide (FeS(2)), demonstrated that the resulting signal intensity of (57)Fe achieved by the fs-laser ablation was almost 4-times higher than that obtained by ArF excimer laser ablation under a similar energy fluence (5 J/cm(2)). In fs-laser ablation, there is no significant difference in a depth of the ablation pit between glass and zircon material, while in ArF laser ablation, the resulting crater depth on the zircon crystal was almost half the level than that obtained for glass material. Both the thermal-induced and particle size-related elemental fractionations, which have been thought to be main sources of analytical error in the LA-ICPMS analysis, were measured on a Harvard 91500 zircon crystal. The resulting fractionation indexes on the (206)Pb/(238)U (f(Pb/U)) and (238)U/(232)Th (f(U/Th)) ratios obtained by the present fs-laser ablation system were significantly smaller than those obtained by a conventional ArF excimer laser ablation system, demonstrative of smaller elemental fractionation. Using the present fs-laser ablation technique, the time profile of the signal intensity of (56)Fe and the isotopic ratios ((57)Fe/(54)Fe and (56)Fe/(54)Fe) have been measured on a natural pyrite (FeS(2)) sample. Repeatability in signal intensity of (56)Fe achieved by the fs-laser ablation system was significantly better than that obtained by ArF excimer laser ablation. Moreover, the resulting precision in (57)Fe/(54)Fe and (56)Fe/(54)Fe ratio measurements could be improved by the fs-laser ablation system

  10. Tsunami waves extensively resurfaced the shorelines of an early Martian ocean

    NASA Astrophysics Data System (ADS)

    Rodriguez, J. Alexis P.; Fairén, Alberto G.; Tanaka, Kenneth L.; Zarroca, Mario; Linares, Rogelio; Platz, Thomas; Komatsu, Goro; Miyamoto, Hideaki; Kargel, Jeffrey S.; Yan, Jianguo; Gulick, Virginia; Higuchi, Kana; Baker, Victor R.; Glines, Natalie

    2016-05-01

    It has been proposed that ~3.4 billion years ago an ocean fed by enormous catastrophic floods covered most of the Martian northern lowlands. However, a persistent problem with this hypothesis is the lack of definitive paleoshoreline features. Here, based on geomorphic and thermal image mapping in the circum-Chryse and northwestern Arabia Terra regions of the northern plains, in combination with numerical analyses, we show evidence for two enormous tsunami events possibly triggered by bolide impacts, resulting in craters ~30 km in diameter and occurring perhaps a few million years apart. The tsunamis produced widespread littoral landforms, including run-up water-ice-rich and bouldery lobes, which extended tens to hundreds of kilometers over gently sloping plains and boundary cratered highlands, as well as backwash channels where wave retreat occurred on highland-boundary surfaces. The ice-rich lobes formed in association with the younger tsunami, showing that their emplacement took place following a transition into a colder global climatic regime that occurred after the older tsunami event. We conclude that, on early Mars, tsunamis played a major role in generating and resurfacing coastal terrains.

  11. Fast growing pseudotumour in a hairdresser after metal-on-metal hip resurfacing: a case report.

    PubMed

    Cadossi, M; Chiarello, E; Savarino, L; Mazzotti, A; Tedesco, G; Greco, M; Giannini, S

    2014-01-01

    A 44-year-old female hairdresser who underwent metal-on-metal hip resurfacing (MOMHR) for hip osteoarthritis developed a benign pelvic pseudotumour. Elevated levels of chromium and cobalt ions were detected in the blood. Patch testing after pseudotumor formation, showed positive skin reactions to cobalt and nickel. Marked hypereosinophilia was noted, as well as the presence of eosinophils in the pseudotumor mass. A revision to a ceramic-on-ceramic implant was performed. Radiographs showed no implant loosening or bone resorption. We hypothesized that a steep cup positioning as well as hypersensitivity response to the metal nanoparticles and ion release may have induced pseudotumour development. Currently there is no evidence that negative patch testing reduces the probability to develop an adverse reaction to metal debris therefore we suggest to carefully investigate patient medical history regarding occupation exposure and daily contact with jewellery, beauty and cleaning products before implanting MOMHR. The main challenge is to identify a sensitive patient candidate to MOMHR never suspected to be. PMID:24825038

  12. Gait and stair function in total and resurfacing hip arthroplasty: a pilot study.

    PubMed

    Shrader, M Wade; Bhowmik-Stoker, Manoshi; Jacofsky, Marc C; Jacofsky, David J

    2009-06-01

    Standard total hip arthroplasty (THA) is the established surgical treatment for patients older than 65 years with progressive osteoarthritis but survivorship curves wane in patients younger than 50. Resurfacing hip arthroplasty (RHA) is an alternative for younger, active patients reportedly providing superior range of motion. Quantitative investigation of functional recovery following arthroplasty may elucidate limitations that aid in device selection. Although limited long-term kinematic data are available, the early rate of recovery and gait compensations are not well described. This information may aid in refining rehabilitation protocols based on limitations specific to the implant. We presumed hip motion and forces for subjects receiving RHA are more similar to age-matched controls during physically demanding tasks, such as stair negotiation, at early time points than those for THA. In a pilot study, we quantified walking and stair negotiation preoperatively and 3 months postoperatively for seven patients with RHA (mean age, 49 years), seven patients with standard THA (mean age, 52 years), and seven age-matched control subjects (mean age, 56 years). Although both treatment groups demonstrated trends toward functional recovery, the RHA group had greater improvements in hip extension and abduction moment indicating typical loading of the hip. Further investigation is needed to determine if differences persist long term or are clinically meaningful. PMID:19305961

  13. Dust levitation as a major resurfacing process on the surface of a saturnian icy satellite, Atlas

    NASA Astrophysics Data System (ADS)

    Hirata, Naoyuki; Miyamoto, Hideaki

    2012-07-01

    A small inner satellite of Saturn, Atlas, has an enigmatic saucer-like shape explained by an accumulation of particles from A-ring of Saturn. However, its unusual smooth surface remains unexplained. Gardening through continuous particle impact events cannot be a unique explanation for the smoothness, because Prometheus does not exhibit a similar surface, though it too would have experienced a similar bombardment. Here, a detailed investigation using close-up images of Atlas reveals the surface to be (1) covered by fine particles (i.e., probably as small as several tens of micrometers); (2) mostly void of impact craters (i.e., only one has been thus far identified); and (3) continuously smooth, even between the equatorial ridge and the undulating polar region. These findings imply that some sort of crater-erasing process has been active on the surface of Atlas. From electro-static analyses, we propose that the upper-most layer of the fine particles can become electro-statically unstable and migrate as a result of dust levitation, which resulted in erasing craters on the surface of Atlas. If true, Atlas would represent the first recognized body where resurfacing is dominated by dust levitation.

  14. Evidence and considerations in the application of chemical peels in skin disorders and aesthetic resurfacing.

    PubMed

    Rendon, Marta I; Berson, Diane S; Cohen, Joel L; Roberts, Wendy E; Starker, Isaac; Wang, Beatrice

    2010-07-01

    Chemical peeling is a popular, relatively inexpensive, and generally safe method for treatment of some skin disorders and to refresh and rejuvenate skin. This article focuses on chemical peels and their use in routine clinical practice. Chemical peels are classified by the depth of action into superficial, medium, and deep peels. The depth of the peel is correlated with clinical changes, with the greatest change achieved by deep peels. However, the depth is also associated with longer healing times and the potential for complications. A wide variety of peels are available, utilizing various topical agents and concentrations, including a recent salicylic acid derivative, beta-lipohydroxy acid, which has properties that may expand the clinical use of peels. Superficial peels, penetrating only the epidermis, can be used to enhance treatment for a variety of conditions, including acne, melasma, dyschromias, photodamage, and actinic keratoses. Medium-depth peels, penetrating to the papillary dermis, may be used for dyschromia, multiple solar keratoses, superficial scars, and pigmentary disorders. Deep peels, affecting reticular dermis, may be used for severe photoaging, deep wrinkles, or scars. Peels can be combined with other in-office facial resurfacing techniques to optimize outcomes and enhance patient satisfaction and allow clinicians to tailor the treatment to individual patient needs. Successful outcomes are based on a careful patient selection as well as appropriate use of specific peeling agents. Used properly, the chemical peel has the potential to fill an important therapeutic need in the dermatologist's and plastic surgeon's armamentarium. PMID:20725555

  15. Evidence and Considerations in the Application of Chemical Peels in Skin Disorders and Aesthetic Resurfacing

    PubMed Central

    Berson, Diane S.; Cohen, Joel L.; Roberts, Wendy E.; Starker, Isaac; Wang, Beatrice

    2010-01-01

    Chemical peeling is a popular, relatively inexpensive, and generally safe method for treatment of some skin disorders and to refresh and rejuvenate skin. This article focuses on chemical peels and their use in routine clinical practice. Chemical peels are classified by the depth of action into superficial, medium, and deep peels. The depth of the peel is correlated with clinical changes, with the greatest change achieved by deep peels. However, the depth is also associated with longer healing times and the potential for complications. A wide variety of peels are available, utilizing various topical agents and concentrations, including a recent salicylic acid derivative, β-lipohydroxy acid, which has properties that may expand the clinical use of peels. Superficial peels, penetrating only the epidermis, can be used to enhance treatment for a variety of conditions, including acne, melasma, dyschromias, photodamage, and actinic keratoses. Medium-depth peels, penetrating to the papillary dermis, may be used for dyschromia, multiple solar keratoses, superficial scars, and pigmentary disorders. Deep peels, affecting reticular dermis, may be used for severe photoaging, deep wrinkles, or scars. Peels can be combined with other in-office facial resurfacing techniques to optimize outcomes and enhance patient satisfaction and allow clinicians to tailor the treatment to individual patient needs. Successful outcomes are based on a careful patient selection as well as appropriate use of specific peeling agents. Used properly, the chemical peel has the potential to fill an important therapeutic need in the dermatologist's and plastic surgeon's armamentarium. PMID:20725555

  16. Impingement and stability of total hip arthroplasty versus femoral head resurfacing using a cadaveric robotics model.

    PubMed

    Colbrunn, R W; Bottros, J J; Butler, R S; Klika, A K; Bonner, T F; Greeson, C; van den Bogert, A J; Barsoum, W K

    2013-07-01

    We identified and compared the impingent-free range of motion (ROM) and subluxation potential for native hip, femoral head resurfacing (FHR), and total hip arthroplasty (THA). These constructs were also compared both with and without soft tissue to elucidate the role of the soft tissue. Five fresh-frozen bilateral hip specimens were mounted to a six-degree of freedom robotic manipulator. Under load-control parameters, in vivo mechanics were recreated to evaluate impingement free ROM, and the subluxation potential in two "at risk" positions for native hip, FHR, and THA. Impingement-free ROM of the skeletonized THA was greater than FHR for the anterior subluxation position. For skeletonized posterior subluxations, stability for THA and FHR constructs were similar, while a different pattern was observed for specimens with soft tissues intact. FHR constructs were more stable than THA constructs for both anterior and posterior subluxations. When the femoral neck is intact the joint has an earlier impingement profile placing the hip at risk for subluxation. However, FHR design was shown to be more stable than THA only when soft tissues were intact. PMID:23494830

  17. Return to sporting activity after Birmingham hip resurfacing arthroplasty: Mid term results

    PubMed Central

    Sandiford, Nemandra; Muirhead-Allwood, SK; Skinner, JA

    2015-01-01

    Background: Hip resurfacing arthroplasty (HRA) is primarily indicated for young, active patients with disabling coxarthrosis who wish to remain active and return to sports after surgery. Relatively few prospective studies have assessed return to sporting activity and impact of gender and age on this. Materials and Methods: Seventy-nine consecutive patients treated with HRA were included. Patients were reviewed clinically and radiologically. Function was assessed using the modified University of California Los Angeles (UCLA) activity score. The Oxford, Harris and WOMAC hip scores were calculated. Results: Average age at the time of surgery was 54.9 years (range 34.5–73.6 years). Average preoperative and postoperative UCLA scores were 4 and 7.6 respectively. Patients were involved in 2 (0–4) sporting activities preoperatively and 2 (0–5) postoperatively. Preoperative and postoperative Oxford Hip Scores, Harris Hip Score and WOMAC scores were 40, 46 and 51 and 16, 94 and 3 respectively (P < 0.0001). Patients returned to sports at an average of 3 months postoperatively. Conclusion: Patients were able to return to sports by 3 months and perform the same number of activities at preoperative intensity. Activity levels are maintained up to the medium term with few complications. PMID:26806965

  18. Tsunami waves extensively resurfaced the shorelines of an early Martian ocean

    PubMed Central

    Rodriguez, J. Alexis P.; Fairén, Alberto G.; Tanaka, Kenneth L.; Zarroca, Mario; Linares, Rogelio; Platz, Thomas; Komatsu, Goro; Miyamoto, Hideaki; Kargel, Jeffrey S.; Yan, Jianguo; Gulick, Virginia; Higuchi, Kana; Baker, Victor R.; Glines, Natalie

    2016-01-01

    It has been proposed that ~3.4 billion years ago an ocean fed by enormous catastrophic floods covered most of the Martian northern lowlands. However, a persistent problem with this hypothesis is the lack of definitive paleoshoreline features. Here, based on geomorphic and thermal image mapping in the circum-Chryse and northwestern Arabia Terra regions of the northern plains, in combination with numerical analyses, we show evidence for two enormous tsunami events possibly triggered by bolide impacts, resulting in craters ~30 km in diameter and occurring perhaps a few million years apart. The tsunamis produced widespread littoral landforms, including run-up water-ice-rich and bouldery lobes, which extended tens to hundreds of kilometers over gently sloping plains and boundary cratered highlands, as well as backwash channels where wave retreat occurred on highland-boundary surfaces. The ice-rich lobes formed in association with the younger tsunami, showing that their emplacement took place following a transition into a colder global climatic regime that occurred after the older tsunami event. We conclude that, on early Mars, tsunamis played a major role in generating and resurfacing coastal terrains. PMID:27196957

  19. Tsunami waves extensively resurfaced the shorelines of an early Martian ocean.

    PubMed

    Rodriguez, J Alexis P; Fairén, Alberto G; Tanaka, Kenneth L; Zarroca, Mario; Linares, Rogelio; Platz, Thomas; Komatsu, Goro; Miyamoto, Hideaki; Kargel, Jeffrey S; Yan, Jianguo; Gulick, Virginia; Higuchi, Kana; Baker, Victor R; Glines, Natalie

    2016-01-01

    It has been proposed that ~3.4 billion years ago an ocean fed by enormous catastrophic floods covered most of the Martian northern lowlands. However, a persistent problem with this hypothesis is the lack of definitive paleoshoreline features. Here, based on geomorphic and thermal image mapping in the circum-Chryse and northwestern Arabia Terra regions of the northern plains, in combination with numerical analyses, we show evidence for two enormous tsunami events possibly triggered by bolide impacts, resulting in craters ~30 km in diameter and occurring perhaps a few million years apart. The tsunamis produced widespread littoral landforms, including run-up water-ice-rich and bouldery lobes, which extended tens to hundreds of kilometers over gently sloping plains and boundary cratered highlands, as well as backwash channels where wave retreat occurred on highland-boundary surfaces. The ice-rich lobes formed in association with the younger tsunami, showing that their emplacement took place following a transition into a colder global climatic regime that occurred after the older tsunami event. We conclude that, on early Mars, tsunamis played a major role in generating and resurfacing coastal terrains. PMID:27196957

  20. Analysis of ablation debris from natural and artificial iron meteorites

    NASA Technical Reports Server (NTRS)

    Blanchard, M. B.; Davis, A. S.

    1977-01-01

    Artificial ablation studies were performed on iron and nickel-iron samples using an arc-heated plasma of ionized air. Experiment conditions simulated a meteoroid traveling about 12 km/sec at an altitude of 70 km. The artificially produced fusion crusts and ablation debris show features very similar to natural fusion crusts of the iron meteorites Boguslavka, Norfork, and N'Kandhla and to magnetic spherules recovered from Mn nodules. X-ray diffraction, electron microprobe, optical, and scanning electron microscope analyses reveal that important mineralogical, elemental, and textural changes occur during ablation. Some metal is melted and ablated. The outer margin of the melted rind is oxidized and recrystallizes as a discontinuous crust of magnetite and wustite. Adjacent to the oxidized metallic ablation zone is an unoxidized metallic ablation zone in which structures such as Widmannstatten bands are obliterated as the metal is transformed to unequilibrated alpha 2 nickel-iron. Volatile elements are vaporized and less volatile elements undergo fractionation.

  1. Ventricular dysfunction following direct-current shock atrioventricular junction ablation.

    PubMed

    Warren, R J; Vohra, J K; Chan, W; Lichtenstein, M; Mond, H G; Hunt, D

    1991-02-01

    Catheter-induced His bundle ablation for refractory supraventricular arrhythmias is most commonly performed with direct-current shock energy of 200-300 joules. The high energy pulse delivered by direct-current shock produces a lesion in the atrioventricular node by fulguration, with the residual energy being dissipated as a pressure wave. The effect of direct-current shock His bundle ablation on global and regional ventricular function was assessed in 14 consecutive patients by radionuclide ventriculography performed before and after ablation and again three months later. All studies were performed with ventricular pacing at 110 bpm. Global left ventricular ejection fraction was found to be significantly reduced at the three month study (0.43 +/- 0.03 vs 0.50 +/- 0.03, pre ablation, p = 0.02). A significant reduction in wall-motion score was also seen in six of the seven patients who had normal wall motion in pacing rhythm prior to ablation. Deterioration was mainly seen at the left and right ventricular apices. The observed reduction in ventricular function that follows direct-current shock His bundle ablation may result from myocardial damage from electro-coagulation or from barotrauma and supports continued investigation into alternative, less traumatic energy sources for the procedure. PMID:2036072

  2. Femtosecond laser ablation elemental mass spectrometry.

    PubMed

    Hergenröder, Roland; Samek, Ota; Hommes, Vanja

    2006-01-01

    Laser ablation mass spectrometry (LA-MS) has always been an interesting method for the elemental analysis of solid samples. Chemical analysis with a laser requires small amounts of material. Depending on the analytical detection system, subpicogram quantities may be sufficient. In addition, a focused laser beam permits the spatial characterization of heterogeneity in solid samples typically with micrometer resolution in terms of lateral and depth dimensions. With the advent of high-energy, ultra-short pulse lasers, new possibilities arise. The task of this review is to discuss the principle differences between the ablation process of short (>1 ps) and ultra-short (<1 ps) pulses. Based on the timescales and the energy balance of the process that underlies an ablation event, it will be shown that ultra-short pulses are less thermal and cause less collateral damages than longer pulses. The confinement of the pulse energy to the focal region guarantees a better spatial resolution in all dimensions and improves the analytical figures of merit (e.g., fractionation). Applications that demonstrate these features and that will be presented are in-depth profiling of multi-layer samples and the elemental analysis of biological materials. PMID:16477613

  3. Radiofrequency Ablation of Metastatic Pheochromocytoma

    PubMed Central

    Venkatesan, Aradhana M.; Locklin, Julia; Lai, Edwin W.; Adams, Karen T.; Fojo, Antonio Tito; Pacak, Karel; Wood, Bradford J.

    2013-01-01

    In the present report on the preliminary safety and effectiveness of radiofrequency (RF) ablation for pheochromocytoma metastases, seven metastases were treated in six patients (mean size, 3.4 cm; range, 2.2–6 cm). α- and β-adrenergic and catecholamine synthesis inhibition and intraprocedural anesthesia monitoring were used. Safety was assessed by recording ablation-related complications. Complete ablation was defined as a lack of enhancement within the ablation zone on follow-up computed tomography. No serious adverse sequelae were observed. Complete ablation was achieved in six of seven metastases (mean follow-up, 12.3 months; range, 2.5–28 months). In conclusion, RF ablation may be safely performed for metastatic pheochromocytoma given careful attention to peri-procedural management. PMID:19875067

  4. OCDR guided laser ablation device

    DOEpatents

    Dasilva, Luiz B.; Colston, Jr., Bill W.; James, Dale L.

    2002-01-01

    A guided laser ablation device. The device includes a mulitmode laser ablation fiber that is surrounded by one or more single mode optical fibers that are used to image in the vicinity of the laser ablation area to prevent tissue damage. The laser ablation device is combined with an optical coherence domain reflectometry (OCDR) unit and with a control unit which initializes the OCDR unit and a high power laser of the ablation device. Data from the OCDR unit is analyzed by the control unit and used to control the high power laser. The OCDR images up to about 3 mm ahead of the ablation surface to enable a user to see sensitive tissue such as a nerve or artery before damaging it by the laser.

  5. Multiple target laser ablation system

    DOEpatents

    Mashburn, Douglas N.

    1996-01-01

    A laser ablation apparatus and method are provided in which multiple targets consisting of material to be ablated are mounted on a movable support. The material transfer rate is determined for each target material, and these rates are stored in a controller. A position detector determines which target material is in a position to be ablated, and then the controller controls the beam trigger timing and energy level to achieve a desired proportion of each constituent material in the resulting film.

  6. Multiple target laser ablation system

    DOEpatents

    Mashburn, D.N.

    1996-01-09

    A laser ablation apparatus and method are provided in which multiple targets consisting of material to be ablated are mounted on a movable support. The material transfer rate is determined for each target material, and these rates are stored in a controller. A position detector determines which target material is in a position to be ablated, and then the controller controls the beam trigger timing and energy level to achieve a desired proportion of each constituent material in the resulting film. 3 figs.

  7. Electrosensitization assists cell ablation by nanosecond pulsed electric field in 3D cultures

    PubMed Central

    Muratori, Claudia; Pakhomov, Andrei G.; Xiao, Shu; Pakhomova, Olga N.

    2016-01-01

    Previous studies reported a delayed increase of sensitivity to electroporation (termed “electrosensitization”) in mammalian cells that had been subjected to electroporation. Electrosensitization facilitated membrane permeabilization and reduced survival in cell suspensions when the electric pulse treatments were split in fractions. The present study was aimed to visualize the effect of sensitization and establish its utility for cell ablation. We used KLN 205 squamous carcinoma cells embedded in an agarose gel and cell spheroids in Matrigel. A local ablation was created by a train of 200 to 600 of 300-ns pulses (50 Hz, 300–600 V) delivered by a two-needle probe with 1-mm inter-electrode distance. In order to facilitate ablation by engaging electrosensitization, the train was split in two identical fractions applied with a 2- to 480-s interval. At 400–600 V (2.9–4.3 kV/cm), the split-dose treatments increased the ablation volume and cell death up to 2–3-fold compared to single-train treatments. Under the conditions tested, the maximum enhancement of ablation was achieved when two fractions were separated by 100 s. The results suggest that engaging electrosensitization may assist in vivo cancer ablation by reducing the voltage or number of pulses required, or by enabling larger inter-electrode distances without losing the ablation efficiency. PMID:26987779

  8. Comparison of Patient-Reported Outcome from Neck-Preserving, Short-Stem Arthroplasty and Resurfacing Arthroplasty in Younger Osteoarthritis Patients

    PubMed Central

    Dettmer, Marius; Pourmoghaddam, Amir; Kreuzer, Stefan W.

    2015-01-01

    Hip resurfacing has been considered a good treatment option for younger, active osteoarthritis patients. However, there are several identified issues concerning risk for neck fractures and issues related to current metal-on-metal implant designs. Neck-preserving short-stem implants have been discussed as a potential alternative, but it is yet unclear which method is better suited for younger adults. We compared hip disability and osteoarthritis outcome scores (HOOS) from a young group of patients (n = 52, age 48.9 ± 6.1 years) who had received hip resurfacing (HR) with a cohort of patients (n = 73, age 48.2 ± 6.6 years) who had received neck-preserving, short-stem implant total hip arthroplasty (THA). Additionally, durations for both types of surgery were compared. HOOS improved significantly preoperatively to last followup (>1 year) in both groups (p < 0.0001, η2 = 0.69); there were no group effects or interactions. Surgery duration was significantly longer for resurfacing (104.4 min ± 17.8) than MiniHip surgery (62.5 min ± 14.8), U = 85.0, p < 0.0001, η2 = 0.56. The neck-preserving short-stem approach may be preferable to resurfacing due to the less challenging surgery, similar outcome, and controversy regarding resurfacing implant designs. PMID:26101669

  9. Anatomically shaped tissue-engineered cartilage with tunable and inducible anticytokine delivery for biological joint resurfacing

    PubMed Central

    Moutos, Franklin T.; Glass, Katherine A.; Compton, Sarah A.; Ross, Alison K.; Gersbach, Charles A.; Estes, Bradley T.

    2016-01-01

    Biological resurfacing of entire articular surfaces represents an important but challenging strategy for treatment of cartilage degeneration that occurs in osteoarthritis. Not only does this approach require anatomically sized and functional engineered cartilage, but the inflammatory environment within an arthritic joint may also inhibit chondrogenesis and induce degradation of native and engineered cartilage. The goal of this study was to use adult stem cells to engineer anatomically shaped, functional cartilage constructs capable of tunable and inducible expression of antiinflammatory molecules, specifically IL-1 receptor antagonist (IL-1Ra). Large (22-mm-diameter) hemispherical scaffolds were fabricated from 3D woven poly(ε-caprolactone) (PCL) fibers into two different configurations and seeded with human adipose-derived stem cells (ASCs). Doxycycline (dox)-inducible lentiviral vectors containing eGFP or IL-1Ra transgenes were immobilized to the PCL to transduce ASCs upon seeding, and constructs were cultured in chondrogenic conditions for 28 d. Constructs showed biomimetic cartilage properties and uniform tissue growth while maintaining their anatomic shape throughout culture. IL-1Ra–expressing constructs produced nearly 1 µg/mL of IL-1Ra upon controlled induction with dox. Treatment with IL-1 significantly increased matrix metalloprotease activity in the conditioned media of eGFP-expressing constructs but not in IL-1Ra–expressing constructs. Our findings show that advanced textile manufacturing combined with scaffold-mediated gene delivery can be used to tissue engineer large anatomically shaped cartilage constructs that possess controlled delivery of anticytokine therapy. Importantly, these cartilage constructs have the potential to provide mechanical functionality immediately upon implantation, as they will need to replace a majority, if not the entire joint surface to restore function. PMID:27432980

  10. Metal release and metal allergy after total hip replacement with resurfacing versus conventional hybrid prosthesis

    PubMed Central

    Gustafson, Klas; Jakobsen, Stig S; Lorenzen, Nina D; Thyssen, Jacob P; Johansen, Jeanne D; Bonefeld, Charlotte M; Stilling, Maiken; Baad-Hansen, Thomas; Søballe, Kjeld

    2014-01-01

    Background Metal-on-metal (MOM) total hip arthroplasties were reintroduced because of the problems with osteolysis and aseptic loosening related to polyethylene wear of early metal-on-polyethylene (MOP) arthroplasties. The volumetric wear rate has been greatly reduced with MOM arthroplasties; however, because of nano-size wear particles, the absolute number has been greatly increased. Thus, a source of metal ion exposure with the potential to sensitize patients is present. We hypothesized that higher amounts of wear particles result in increased release of metal ions and ultimately lead to an increased incidence of metal allergy. Methods 52 hips in 52 patients (median age 60 (51–64) years, 30 women) were randomized to either a MOM hip resurfacing system (ReCap) or a standard MOP total hip arthoplasty (Mallory Head/Exeter). Spot urine samples were collected preoperatively, postoperatively, after 3 months, and after 1, 2, and 5 years and tested with inductively coupled plasma-sector field mass spectrometry. After 5 years, hypersensitivity to metals was evaluated by patch testing and lymphocyte transformation assay. In addition, the patients answered a questionnaire about hypersensitivity. Results A statistically significant 10- to 20-fold increase in urinary levels of cobalt and chromium was observed throughout the entire follow-up in the MOM group. The prevalence of metal allergy was similar between groups. Interpretation While we observed significantly increased levels of metal ions in the urine during the entire follow-up period, no difference in prevalence of metal allergy was observed in the MOM group. However, the effect of long-term metal exposure remains uncertain. PMID:24930546

  11. Anatomically shaped tissue-engineered cartilage with tunable and inducible anticytokine delivery for biological joint resurfacing.

    PubMed

    Moutos, Franklin T; Glass, Katherine A; Compton, Sarah A; Ross, Alison K; Gersbach, Charles A; Guilak, Farshid; Estes, Bradley T

    2016-08-01

    Biological resurfacing of entire articular surfaces represents an important but challenging strategy for treatment of cartilage degeneration that occurs in osteoarthritis. Not only does this approach require anatomically sized and functional engineered cartilage, but the inflammatory environment within an arthritic joint may also inhibit chondrogenesis and induce degradation of native and engineered cartilage. The goal of this study was to use adult stem cells to engineer anatomically shaped, functional cartilage constructs capable of tunable and inducible expression of antiinflammatory molecules, specifically IL-1 receptor antagonist (IL-1Ra). Large (22-mm-diameter) hemispherical scaffolds were fabricated from 3D woven poly(ε-caprolactone) (PCL) fibers into two different configurations and seeded with human adipose-derived stem cells (ASCs). Doxycycline (dox)-inducible lentiviral vectors containing eGFP or IL-1Ra transgenes were immobilized to the PCL to transduce ASCs upon seeding, and constructs were cultured in chondrogenic conditions for 28 d. Constructs showed biomimetic cartilage properties and uniform tissue growth while maintaining their anatomic shape throughout culture. IL-1Ra-expressing constructs produced nearly 1 µg/mL of IL-1Ra upon controlled induction with dox. Treatment with IL-1 significantly increased matrix metalloprotease activity in the conditioned media of eGFP-expressing constructs but not in IL-1Ra-expressing constructs. Our findings show that advanced textile manufacturing combined with scaffold-mediated gene delivery can be used to tissue engineer large anatomically shaped cartilage constructs that possess controlled delivery of anticytokine therapy. Importantly, these cartilage constructs have the potential to provide mechanical functionality immediately upon implantation, as they will need to replace a majority, if not the entire joint surface to restore function. PMID:27432980

  12. Strain and micromotion in intact and resurfaced composite femurs: experimental and numerical investigations.

    PubMed

    Pal, Bidyut; Gupta, Sanjay; New, Andrew M R; Browne, Martin

    2010-07-20

    Understanding the load transfer within a resurfaced femur is necessary to determine the influence of mechanical factors on potential failure mechanisms such as early femoral neck fractures and stress shielding. In this study, an attempt has been made to measure the stem-bone micromotion and implant cup-bone relative displacements (along medial-lateral and anterior-posterior direction), in addition to surface strains at different locations and orientations on the proximal femur and to compare these measurements with those predicted by equivalent FE models. The loading and the support conditions of the experiment were closely replicated in the FE models. A new experimental set-up has been developed, with specially designed fixtures and load application mechanism, which can effectively impose bending and deflection of the tested femurs, almost in any direction. High correlation coefficient (0.92-0.95), low standard error of the estimate (170-379 muepsilon) and low percentage error in regression slope (12.8-17.5%), suggested good agreement between the numerical and measured strains. The effect of strain shielding was observed in two (out of eight) strain gauges located on the posterior side. A pronounced strain increase occurred in strain gauges located on the anterior head and neck regions after implantation. Experimentally measured stem-bone micromotion and implant cup-bone relative displacements (0-13.7 microm) were small and similar in trends predicted by the FE models (0-25 microm). Despite quantitative deviations in the measured and numerical results, it appears that the FE model can be used as a valid predictor of the actual strain and stem-bone micromotion. PMID:20392448

  13. Implantation of scaffold-free engineered cartilage constructs in a rabbit model for chondral resurfacing.

    PubMed

    Brenner, Jillian M; Ventura, Nicole M; Tse, M Yat; Winterborn, Andrew; Bardana, Davide D; Pang, Stephen C; Hurtig, Mark B; Waldman, Stephen D

    2014-02-01

    Joint resurfacing techniques offer an attractive treatment for damaged or diseased cartilage, as this tissue characteristically displays a limited capacity for self-repair. While tissue-engineered cartilage constructs have shown efficacy in repairing focal cartilage defects in animal models, a substantial number of cells are required to generate sufficient quantities of tissue for the repair of larger defects. In a previous study, we developed a novel approach to generate large, scaffold-free cartilaginous constructs from a small number of donor cells (20 000 cells to generate a 3-cm(2) tissue construct). As comparable thicknesses to native cartilage could be achieved, the purpose of the present study was to assess the ability of these constructs to survive implantation as well as their potential for the repair of critical-sized chondral defects in a rabbit model. Evaluated up to 6 months post-implantation, allogenic constructs survived weight bearing without a loss of implant fixation. Implanted constructs appeared to integrate near-seamlessly with the surrounding native cartilage and also to extensively remodel with increasing time in vivo. By 6 months post-implantation, constructs appeared to adopt both a stratified (zonal) appearance and a biochemical composition similar to native articular cartilage. In addition, constructs that expressed superficial zone markers displayed higher histological scores, suggesting that transcriptional prescreening of constructs prior to implantation may serve as an approach to achieve superior and/or more consistent reparative outcomes. As the results of this initial animal study were encouraging, future studies will be directed toward the repair of chondral defects in more mechanically demanding anatomical locations. PMID:24571514

  14. Development of Naphthalene PLIF for Making Quantitative Measurements of Ablation Products Transport in Supersonic Flows

    NASA Astrophysics Data System (ADS)

    Combs, Christopher; Clemens, Noel

    2014-11-01

    Ablation is a multi-physics process involving heat and mass transfer and codes aiming to predict ablation are in need of experimental data pertaining to the turbulent transport of ablation products for validation. Low-temperature sublimating ablators such as naphthalene can be used to create a limited physics problem and simulate ablation at relatively low temperature conditions. At The University of Texas at Austin, a technique is being developed that uses planar laser-induced fluorescence (PLIF) of naphthalene to visualize the transport of ablation products in a supersonic flow. In the current work, naphthalene PLIF will be used to make quantitative measurements of the concentration of ablation products in a Mach 5 turbulent boundary layer. For this technique to be used for quantitative research in supersonic wind tunnel facilities, the fluorescence properties of naphthalene must first be investigated over a wide range of state conditions and excitation wavelengths. The resulting calibration of naphthalene fluorescence will be applied to the PLIF images of ablation from a boundary layer plug, yielding 2-D fields of naphthalene mole fraction. These images may help provide data necessary to validate computational models of ablative thermal protection systems for reentry vehicles. Work supported by NASA Space Technology Research Fellowship Program under grant NNX11AN55H.

  15. Fractional oscillator.

    PubMed

    Stanislavsky, A A

    2004-11-01

    We consider a fractional oscillator which is a generalization of the conventional linear oscillator in the framework of fractional calculus. It is interpreted as an ensemble average of ordinary harmonic oscillators governed by a stochastic time arrow. The intrinsic absorption of the fractional oscillator results from the full contribution of the harmonic oscillator ensemble: these oscillators differ a little from each other in frequency so that each response is compensated by an antiphase response of another harmonic oscillator. This allows one to draw a parallel in the dispersion analysis for media described by a fractional oscillator and an ensemble of ordinary harmonic oscillators with damping. The features of this analysis are discussed. PMID:15600586

  16. High temperature ablative foam

    NASA Technical Reports Server (NTRS)

    Liu, Matthew T. (Inventor)

    1992-01-01

    An ablative foam composition is formed of approximately 150 to 250 parts by weight polymeric isocyanate having an isocyanate functionality of 2.6 to 3.2; approximately 15 to 30 parts by weight reactive flame retardant having a hydroxyl number range from 200-260; approximately 10 to 40 parts by weight non-reactive flame retardant; approximately 10 to 40 parts by weight nonhydrolyzable silicone copolymer having a hydroxyl number range from 75-205; and approximately 3 to 16 parts by weight amine initiated polyether resin having an isocyanate functionality greater than or equal to 3.0 and a hydroxyl number range from 400-800.

  17. LASER ABLATION STUDIES OF CONCRETE

    EPA Science Inventory

    Laser ablation was studied as a means of removing radioactive contaminants from the surface and near-surface regions of concrete. We present the results of ablation tests on cement and concrete samples using a 1.6 kW pulsed Nd:YAG laser with fiber optic beam delivery. The laser-s...

  18. Atrial Fibrillation Ablation in Systolic Dysfunction: Clinical and Echocardiographic Outcomes

    PubMed Central

    Lobo, Tasso Julio; Pachon, Carlos Thiene; Pachon, Jose Carlos; Pachon, Enrique Indalecio; Pachon, Maria Zelia; Pachon, Juan Carlos; Santillana, Tomas Guillermo; Zerpa, Juan Carlos; Albornoz, Remy Nelson; Jatene, Adib Domingos

    2015-01-01

    Background Heart failure and atrial fibrillation (AF) often coexist in a deleterious cycle. Objective To evaluate the clinical and echocardiographic outcomes of patients with ventricular systolic dysfunction and AF treated with radiofrequency (RF) ablation. Methods Patients with ventricular systolic dysfunction [ejection fraction (EF) <50%] and AF refractory to drug therapy underwent stepwise RF ablation in the same session with pulmonary vein isolation, ablation of AF nests and of residual atrial tachycardia, named "background tachycardia". Clinical (NYHA functional class) and echocardiographic (EF, left atrial diameter) data were compared (McNemar test and t test) before and after ablation. Results 31 patients (6 women, 25 men), aged 37 to 77 years (mean, 59.8±10.6), underwent RF ablation. The etiology was mainly idiopathic (19 p, 61%). During a mean follow-up of 20.3±17 months, 24 patients (77%) were in sinus rhythm, 11 (35%) being on amiodarone. Eight patients (26%) underwent more than one procedure (6 underwent 2 procedures, and 2 underwent 3 procedures). Significant NYHA functional class improvement was observed (pre-ablation: 2.23±0.56; postablation: 1.13±0.35; p<0.0001). The echocardiographic outcome also showed significant ventricular function improvement (EF pre: 44.68%±6.02%, post: 59%±13.2%, p=0.0005) and a significant left atrial diameter reduction (pre: 46.61±7.3 mm; post: 43.59±6.6 mm; p=0.026). No major complications occurred. Conclusion Our findings suggest that AF ablation in patients with ventricular systolic dysfunction is a safe and highly effective procedure. Arrhythmia control has a great impact on ventricular function recovery and functional class improvement. PMID:25387404

  19. Mortality rates at 10 years after metal-on-metal hip resurfacing compared with total hip replacement in England: retrospective cohort analysis of hospital episode statistics

    PubMed Central

    Kendal, Adrian R; Prieto-Alhambra, Daniel; Arden, Nigel K; Judge, Andrew

    2013-01-01

    Objectives To compare 10 year mortality rates among patients undergoing metal-on-metal hip resurfacing and total hip replacement in England. Design Retrospective cohort study. Setting English hospital episode statistics database linked to mortality records from the Office for National Statistics. Population All adults who underwent primary elective hip replacement for osteoarthritis from April 1999 to March 2012. The exposure of interest was prosthesis type: cemented total hip replacement, uncemented total hip replacement, and metal-on-metal hip resurfacing. Confounding variables included age, sex, Charlson comorbidity index, rurality, area deprivation, surgical volume, and year of operation. Main outcome measures All cause mortality. Propensity score matching was used to minimise confounding by indication. Kaplan-Meier plots estimated the probability of survival up to 10 years after surgery. Multilevel Cox regression modelling, stratified on matched sets, described the association between prosthesis type and time to death, accounting for variation across hospital trusts. Results 7437 patients undergoing metal-on-metal hip resurfacing were matched to 22 311 undergoing cemented total hip replacement; 8101 patients undergoing metal-on-metal hip resurfacing were matched to 24 303 undergoing uncemented total hip replacement. 10 year rates of cumulative mortality were 271 (3.6%) for metal-on-metal hip resurfacing versus 1363 (6.1%) for cemented total hip replacement, and 239 (3.0%) for metal-on-metal hip resurfacing versus 999 (4.1%) for uncemented total hip replacement. Patients undergoing metal-on-metal hip resurfacing had an increased survival probability (hazard ratio 0.51 (95% confidence interval 0.45 to 0.59) for cemented hip replacement; 0.55 (0.47 to 0.65) for uncemented hip replacement). There was no evidence for an interaction with age or sex. Conclusions Patients with hip osteoarthritis undergoing metal-on-metal hip resurfacing have reduced mortality in

  20. The Fatigue of Water Ice: Insight into the Tectonic Resurfacing of Tidally Deformed Icy Satellites

    NASA Astrophysics Data System (ADS)

    Hammond, N. P.; Barr, A. C.; Hirth, G.; Cooper, R. F.

    2015-12-01

    allow us to determine how subcritical crack growth rates vary as a function of stress intensity, temperature and frequency. We will use our data to extrapolate to conditions present in the near-surface of icy satellites to determine the effect of fatigue on icy satellite resurfacing. [1] Hubner H. and Jillik J., (1977) J. Material Sci. 12.

  1. Thermal response and ablation characteristics of light weight ceramic ablators

    NASA Technical Reports Server (NTRS)

    Tran, Huy K.; Rasky, Daniel J.; Esfahani, Lili

    1993-01-01

    An account is given of the thermal performance and ablation characteristics of the NASA-Ames Lightweight Ceramic Ablators (LCAs) in supersonic, high-enthalpy convective environments, which use low density ceramic or carbon fiber matrices as substrates for main structural support, with organic resin fillers. LCA densities are in the 0.224-1.282 g/cu cm range. In-depth temperature data have been obtained to determine thermal penetration depths and conductivity. The addition of SiC and PPMA is noted to significantly improve the ablation performance of LCAs with silica substrates. Carbon-based LCAs are the most mass-efficient at high flux levels.

  2. Electrophysiological mapping and radiofrequency catheter ablation for ventricular tachycardia in a patient with peripartum cardiomyopathy.

    PubMed

    Tokuda, Michifumi; Stevenson, William G; Nagashima, Koichi; Rubin, David A

    2013-11-01

    A 38-year-old female with prior failed endocardial ablation for ventricular tachycardia (VT) was referred for further treatment. She had been diagnosed with peripartum cardiomyopathy 7 years before and had persistent left ventricular dysfunction with an ejection fraction of 20%. Epicardial voltage mapping showed extensive epicardial scar despite absence of endocardial scar. Five distinct VT morphologies were induced. Ablation was aided by electrogram characteristics, pace mapping, entrainment mapping, and establishing electrical inexcitability along areas of epicardial scar. After epicardial ablation no sustained VT was induced. She had been doing well without VT occurrence but died 1 year later unexpectedly at home. PMID:24102817

  3. Ultrasonic characterization of laser ablation

    NASA Astrophysics Data System (ADS)

    Smith, J. A.; Telschow, K. L.

    When a pulsed laser beam strikes the surface of an absorbing material, ultrasonic waves are generated due to thermoelectric expansion and, at higher laser power densities, ablation of the material. These sound generation mechanisms have been the subject of numerous theoretical and experimental studies and are now fairly well understood. In particular, it has been established that at low power densities the thermoelastic mechanism is well described by a surface center of expansion. This mechanism produces a characteristic waveform whose amplitude is proportional to the energy absorbed from the laser pulse and also dependent on the thermal and elastic properties of the material. The ablation ultrasonic source can be described by a point normal force acting on the material surface. For laser power densities near the ablation onset, the time dependence of the source is that of the laser pulse. The resultant waveform recorded on epicenter (source and detector collinear) has a sharp peak determined by the momentum impulse delivered to the material by the ablation process. Particularly in the near ablation onset region, this ultrasonic displacement peak can be used to characterize the ablation process occurring at the material surface. The onset power density for ablation and subsequent ablation dependence on power density are material dependent and thought to be a function of the heat capacity and thermal conductivity of the material. With this in mind, it is possible that these ablation signals could be used to characterize material microstructures, and perhaps material mechanical properties such as hardness, through microstructural changes of the material thermal parameters. This paper explores this question for samples of Type 304 stainless steel with microstructures controlled through work hardening and annealing.

  4. Current ablation techniques for persistent atrial fibrillation: results of the European Heart Rhythm Association Survey.

    PubMed

    Dagres, Nikolaos; Bongiorni, Maria Grazia; Larsen, Torben Bjerregaard; Hernandez-Madrid, Antonio; Pison, Laurent; Blomström-Lundqvist, Carina

    2015-10-01

    The aim of this survey was to provide insight into current practice regarding ablation of persistent atrial fibrillation (AF) among members of the European Heart Rhythm Association electrophysiology research network. Thirty centres responded to the survey. The main ablation technique for first-time ablation was stand-alone pulmonary vein isolation (PVI): in 67% of the centres for persistent but not long-standing AF and in 37% of the centres for long-standing persistent AF as well. Other applied techniques were ablation of fractionated electrograms, placement of linear lesions, stepwise approach until AF termination, and substrate mapping and isolation of low-voltage areas. However, the percentage of centres applying these techniques during first ablation did not exceed 25% for any technique. When stand-alone PVI was performed in patients with persistent but not long-standing AF, the majority (80%) of the centres used an irrigated radiofrequency ablation catheter whereas 20% of the respondents used the cryoballoon. Similar results were reported for ablation of long-standing persistent AF (radiofrequency 90%, cryoballoon 10%). Neither rotor mapping nor one-shot ablation tools were used as the main first-time ablation methods. Systematic search for non-pulmonary vein triggers was performed only in 10% of the centres. Most common 1-year success rate off antiarrhythmic drugs was 50-60%. Only 27% of the centres knew their 5-year results. In conclusion, patients with persistent AF represent a significant proportion of AF patients undergoing ablation. There is a shift towards stand-alone PVI being the primary choice in many centres for first-time ablation in these patients. The wide variation in the use of additional techniques and in the choice of endpoints reflects the uncertainties and lack of guidance regarding the most optimal approach. Procedural success rates are modest and long-term outcomes are unknown in most centres. PMID:26498718

  5. Ablative heat shield design for space shuttle

    NASA Technical Reports Server (NTRS)

    Seiferth, R. W.

    1973-01-01

    Ablator heat shield configuration optimization studies were conducted for the orbiter. Ablator and reusable surface insulation (RSI) trajectories for design studies were shaped to take advantage of the low conductance of ceramic RSI and high temperature capability of ablators. Comparative weights were established for the RSI system and for direct bond and mechanically attached ablator systems. Ablator system costs were determined for fabrication, installation and refurbishment. Cost penalties were assigned for payload weight penalties, if any. The direct bond ablator is lowest in weight and cost. A mechanically attached ablator using a magnesium subpanel is highly competitive for both weight and cost.

  6. Advances in Atrial Fibrillation Ablation

    PubMed Central

    Darge, Alicia; Reynolds, Matthew R.; Germano, Joseph J.

    2009-01-01

    Atrial Fibrillation (AF) is an increasingly common and costly medical problem.1–3 Given the disappointing efficacy and side effects associated with pharmacological therapy for AF, new treatment options are needed. Over the last decade, advances in our understanding of the mechanisms of AF, coupled with iterative improvements in catheter ablation techniques, have spurred the evolution of catheter ablation for AF from an experimental procedure to an increasingly important treatment option.4 This paper will review recent advances in the approaches and outcomes of AF ablation. PMID:19411729

  7. Epicardial Ablation For Ventricular Tachycardia

    PubMed Central

    Maccabelli, Giuseppe; Mizuno, Hiroya; Della Bella, Paolo

    2012-01-01

    Epicardial ablation has lately become a necessary tool to approach some ventricular tachycardias in different types of cardiomyopathy. Its diffusion is now limited to a few high volume centers not because of the difficulty of the pericardial puncture but since it requires high competence not only in the VT ablation field but also in knowing and recognizing the possible complications each of which require a careful treatment. This article will review the state of the art of epicardial ablation with special attention to the procedural aspects and to the possible selection criteria of the patients PMID:23233758

  8. [Percutaneous ablation of renal tumors: radiofrequency ablation or cryoablation?].

    PubMed

    Buy, X; Lang, H; Garnon, J; Gangi, A

    2011-09-01

    Percutaneous ablation of renal tumors, including radiofrequency ablation and cryoablation, are increasingly being used for small tumors as an alternative to surgery for poor surgical candidates. Compared to radiofrequency ablation, cryoablation has several advantages: improved volume control and preservation of adjacent structures due to the excellent depiction of the ice ball on CT and MRI; better protection of the collecting system for central tumor with reduced risk of postprocedural urinary fistula. The main pitfall of cryoablation is the higher cost. Therefore, cryoablation should be reserved for the treatment of complex tumors. In this article, we will review the different steps of percutaneous renal tumor ablation procedures including patient selection, technical considerations, and follow-up imaging. PMID:21944236

  9. Ion acceleration enhanced by target ablation

    SciTech Connect

    Zhao, S.; Lin, C. Wang, H. Y.; Lu, H. Y.; He, X. T.; Yan, X. Q.; Chen, J. E.; Cowan, T. E.

    2015-07-15

    Laser proton acceleration can be enhanced by using target ablation, due to the energetic electrons generated in the ablation preplasma. When the ablation pulse matches main pulse, the enhancement gets optimized because the electrons' energy density is highest. A scaling law between the ablation pulse and main pulse is confirmed by the simulation, showing that for given CPA pulse and target, proton energy improvement can be achieved several times by adjusting the target ablation.

  10. TPS Ablator Technologies for Interplanetary Spacecraft

    NASA Technical Reports Server (NTRS)

    Curry, Donald M.

    2004-01-01

    This slide presentation reviews the status of Thermal Protection System (TPS) Ablator technologies and the preparation for use in interplanetary spacecraft. NASA does not have adequate TPS ablatives and sufficient selection for planned missions. It includes a comparison of shuttle and interplanetary TPS requirements, the status of mainline TPS charring ablator materials, a summary of JSC SBIR accomplishments in developing advanced charring ablators and the benefits of SBIR Ablator/fabrication technology.

  11. Fraction Reduction through Continued Fractions

    ERIC Educational Resources Information Center

    Carley, Holly

    2011-01-01

    This article presents a method of reducing fractions without factoring. The ideas presented may be useful as a project for motivated students in an undergraduate number theory course. The discussion is related to the Euclidean Algorithm and its variations may lead to projects or early examples involving efficiency of an algorithm.

  12. Usefulness of Skin Explants for Histologic Analysis after Fractional Photothermolysis

    PubMed Central

    Park, Gyeong-Hun; Bang, Seunghyun; Won, Kwang Hee; Won, Chong Hyun; Lee, Mi Woo; Choi, Jee Ho; Moon, Kee Chan

    2015-01-01

    Background Fractional laser resurfacing treatment has been extensively investigated and is widely used. However, the mechanism underlying its effects is poorly understood because of the ethical and cosmetic problems of obtaining skin biopsies required to study the changes after laser treatment. Objective To evaluate the usefulness of human skin explants for the investigation of fractional photothermolysis. Methods Full-thickness discarded skin was treated in 4 ways: no treatment (control), fractional carbon dioxide laser, fractional Er:YAG laser, and fractional 1,550-nm erbium-doped fiber laser. Both treated and non-treated skin samples were cultured ex vivo at the air-medium interface for 7 days. Frozen tissue was sectioned and stained with hematoxylin & eosin for histologic examination and nitro blue tetrazolium chloride for viability testing. Results Skin explants cultured for up to 3 days exhibited histologic changes similar to those observed in in vivo studies, including microscopic treatment zones surrounded by a thermal coagulation zone, re-epithelialization, and formation of microscopic epidermal necrotic debris. However, the explant structure lost its original form within 7 days of culture. The viability of skin explants was maintained for 3 days of culture but was also lost within 7 days. Conclusion The skin explant model may be a useful tool for investigating the immediate or early changes following fractional photothermolysis, but further improvements are required to evaluate the long-term and dermal changes. PMID:26082585

  13. Hypofractionated ablative radiotherapy for locally advanced pancreatic cancer

    PubMed Central

    Crane, Christopher H.

    2016-01-01

    The role of radiation in locally advanced unresectable pancreatic cancer (LAPC) is controversial. Randomized trials evaluating standard doses of chemoradiation have not shown a significant benefit from the use of consolidative radiation. Results from non-randomized studies of 3–5-fraction stereotactic body radiotherapy (SBRT) have been similar to standard chemoradiation, but with less toxicity and a shorter treatment time. Doses of SBRT have been reduced to subablative levels for the sake of tolerability. The benefit of both options is unclear. In contrast, ablative doses can be delivered using an SBRT technique in 15–28 fractions. The keys to the delivery of ablative doses are computed tomography (CT) image guidance and respiratory gating. Higher doses have resulted in encouraging long-term survival results. In this review, we present a comprehensive solution to achieving ablative doses for selected patients with pancreatic tumors by using a combination of classical, modern and novel concepts of radiotherapy: fractionation, CT image guidance, respiratory gating, intentional dose heterogeneity, and simultaneous integrated protection. PMID:27029741

  14. Cryoballoon Ablation for Atrial Fibrillation

    PubMed Central

    Andrade, Jason G; Dubuc, Marc; Guerra, Peter G; Macle, Laurent; Rivard, Lena; Roy, Denis; Talajic, Mario; Thibault, Bernard; Khairy, Paul

    2012-01-01

    Focal point-by-point radiofrequency catheter ablation has shown considerable success in the treatment of paroxysmal atrial fibrillation. However, it is not without limitations. Recent clinical and preclinical studies have demonstrated that cryothermal ablation using a balloon catheter (Artic Front©, Medtronic CryoCath LP) provides an effective alternative strategy to treating atrial fibrillation. The objective of this article is to review efficacy and safety data surrounding cryoballoon ablation for paroxysmal and persistent atrial fibrillation. In addition, a practical step-by-step approach to cryoballoon ablation is presented, while highlighting relevant literature regarding: 1) the rationale for adjunctive imaging, 2) selection of an appropriate cryoballoon size, 3) predictors of efficacy, 4) advanced trouble-shooting techniques, and 5) strategies to reduce procedural complications, such as phrenic nerve palsy. PMID:22557842

  15. Bipedicled Preexpanded Forehead Flaps for Simultaneous Reconstruction of Total Nasal and Upper Lip Subunits: A Novel Approach to Complex Facial Resurfacing.

    PubMed

    Su, Weijie; Min, Peiru; Sadigh, Parviz; Grassetti, Luca; Lazzeri, Davide; Munnee, Krishna; Pu, Zheming; Zhang, Yixin

    2016-06-01

    Background Reconstruction of the central facial subunits is a complex and challenging task. In cases in which both the nasal and upper lip subunits are involved, a technique that can reconstruct both aesthetic units with tissue of similar color and texture from a single donor site will be ideal. In this article we present our experience with the bipedicled preexpanded forehead flap for simultaneous nasal and upper lip resurfacing. Patients and Methods Between January 2012 and January 2015 we used this technique in the simultaneous reconstruction of total nasal and upper lip subunits in five patients. All cases were for burns scar resurfacing. Results Good aesthetic results were achieved in each of our five cases to date and no complications were encountered. All donor sites closed primarily with aesthetically pleasing well-concealed linear scars. In all cases small modifications such as philtral shaping and further flap thinning were performed under local anesthesia between 6 and 12 months postoperatively Conclusion The preexpanded forehead flap provides an unparalleled color and texture match when it comes to facial resurfacing. When both total nasal and upper lip resurfacings are required, it is possible to achieve this in a single sitting from a single donor site by using a bipedicled preexpanded forehead flap. PMID:27128261

  16. CO2 Laser Absorption in Ablation Plasmas

    SciTech Connect

    Eckel, Hans-Albert; Tegel, Jochen; Schall, Wolfgang O.

    2006-05-02

    The impulse formation by laser ablation is limited by the premature absorption of the incident laser radiation in the initially produced cloud of ablation products. The power fraction of a CO2 laser pulse transmitted through a small hole in a POM sample for pulse energies of 35 to 150 J focused on a spot of 2 cm2 has been compared with the incident power. The plasma formation in vacuum and in air of 3500 Pa and the spread of the shock wave with velocities of 1.6 to 2.4 km/s in the low pressure air was observed by Schlieren photography. A sharp edged dark zone with a maximum extension of 10 to 12 mm away from the target surface develops within 5 {mu}s independently of the pressure and is assumed to be a plasma. In order to find out, if this is also the zone where the majority of the incident laser radiation is absorbed, a CO2 probe laser beam was directed through the expansion cloud parallel to and at various distances from the sample surface. The time behavior of the absorption signal of the probe beam has been measured and an absorption wave could be observed.

  17. Laser ablation in analytical chemistry.

    PubMed

    Russo, Richard E; Mao, Xianglei; Gonzalez, Jhanis J; Zorba, Vassilia; Yoo, Jong

    2013-07-01

    In 2002, we wrote an Analytical Chemistry feature article describing the Physics of Laser Ablation in Microchemical Analysis. In line with the theme of the 2002 article, this manuscript discusses current issues in fundamental research, applications based on detecting photons at the ablation site (LIBS and LAMIS) and by collecting particles for excitation in a secondary source (ICP), and directions for the technology. PMID:23614661

  18. Bone and Soft Tissue Ablation

    PubMed Central

    Foster, Ryan C.B.; Stavas, Joseph M.

    2014-01-01

    Bone and soft tissue tumor ablation has reached widespread acceptance in the locoregional treatment of various benign and malignant musculoskeletal (MSK) lesions. Many principles of ablation learned elsewhere in the body are easily adapted to the MSK system, particularly the various technical aspects of probe/antenna design, tumoricidal effects, selection of image guidance, and methods to reduce complications. Despite the common use of thermal and chemical ablation procedures in bone and soft tissues, there are few large clinical series that show longitudinal benefit and cost-effectiveness compared with conventional methods, namely, surgery, external beam radiation, and chemotherapy. Percutaneous radiofrequency ablation of osteoid osteomas has been evaluated the most and is considered a first-line treatment choice for many lesions. Palliation of painful metastatic bone disease with thermal ablation is considered safe and has been shown to reduce pain and analgesic use while improving quality of life for cancer patients. Procedure-related complications are rare and are typically easily managed. Similar to all interventional procedures, bone and soft tissue lesions require an integrated approach to disease management to determine the optimum type of and timing for ablation techniques within the context of the patient care plan. PMID:25053865

  19. Bone and soft tissue ablation.

    PubMed

    Foster, Ryan C B; Stavas, Joseph M

    2014-06-01

    Bone and soft tissue tumor ablation has reached widespread acceptance in the locoregional treatment of various benign and malignant musculoskeletal (MSK) lesions. Many principles of ablation learned elsewhere in the body are easily adapted to the MSK system, particularly the various technical aspects of probe/antenna design, tumoricidal effects, selection of image guidance, and methods to reduce complications. Despite the common use of thermal and chemical ablation procedures in bone and soft tissues, there are few large clinical series that show longitudinal benefit and cost-effectiveness compared with conventional methods, namely, surgery, external beam radiation, and chemotherapy. Percutaneous radiofrequency ablation of osteoid osteomas has been evaluated the most and is considered a first-line treatment choice for many lesions. Palliation of painful metastatic bone disease with thermal ablation is considered safe and has been shown to reduce pain and analgesic use while improving quality of life for cancer patients. Procedure-related complications are rare and are typically easily managed. Similar to all interventional procedures, bone and soft tissue lesions require an integrated approach to disease management to determine the optimum type of and timing for ablation techniques within the context of the patient care plan. PMID:25053865

  20. Metal ion levels and functional results after either resurfacing hip arthroplasty or conventional metal-on-metal hip arthroplasty

    PubMed Central

    2011-01-01

    Background Modern metal-on-metal hip resurfacing was introduced as a bone-preserving method of joint reconstruction for young and active patients; however, the large diameter of the bearing surfaces is of concern for potentially increased metal ion release. Patients and methods 71 patients (< 65 years old) were randomly assigned to receive either a resurfacing (R) hip arthroplasty (n = 38) or a conventional metal-on-metal (C) hip arthroplasty (n = 33). Functional outcomes were assessed preoperatively and at 6, 12, and 24 months. Cobalt and chromium blood levels were analyzed preoperatively and at 3, 6, 12, and 24 months. Results All functional outcome scores improved for both groups. At 12 and 24 months, the median UCLA activity score was 8 in the R patients and 7 in the C patients (p < 0.05). At 24 months, OHS was median 16 in C patients and 13 in R patients (p < 0.05). However, in spite of randomization, UCLA scores also appeared to be higher in R patients at baseline. Satisfaction was similar in both groups at 24 months. Cobalt concentrations were statistically significantly higher for R patients only at 3 and 6 months. Chromium levels remained significantly higher for R patients until 24 months. No pseudotumors were encountered in either group. One R patient was revised for early aseptic loosening and in 2 C patients a cup insert was exchanged for recurrent dislocation. Interpretation R patients scored higher on UCLA, OHS, and satisfaction at some time points; however, as for the UCLA, preoperative levels were already in favor of R. The differences, although statistically significant, were of minor clinical importance. Chromium blood levels were statistically significantly higher for R patients at all follow-up measurements, whereas for cobalt this was only observed up to 6 months. The true value of resurfacing hip arthroplasty over conventional metal-on-metal hip arthroplasty will be determined by longer follow-up and a possible shift of balance between their

  1. Effect of acetabular cup design on metal ion release in two designs of metal-on-metal hip resurfacing.

    PubMed

    Cadossi, Matteo; Tedesco, Giuseppe; Savarino, Lucia; Baldini, Nicola; Mazzotti, Antonio; Greco, Michelina; Giannini, Sandro

    2014-10-01

    The purpose of this observational prospective cohort study was to evaluate the serum concentrations of cobalt (Co), chromium (Cr), and nickel (Ni) at a 2-year follow-up in patients operated on with a novel design of hip resurfacing: Romax resurfacing system (RRS). RRS is characterized by the presence of an acetabular notch which theoretically provides a wider range of motion and a reduced incidence of groin pain. The presence of radiolucencies and functional outcome, assessed using the Harris hip score (HHS) and the University of California Activity scale (UCLA), were secondary endpoints. Moreover, these results were compared with those obtained in our previous study from a similar cohort of patients implanted using the Birmingham Hip Resurfacing (BHR) system. At a 2-year follow-up, the serum levels of Co in patients operated on using the RRS were five times higher (p = 0.0002) than those found before surgery (Co, means: 1.04 and 0.20 ng/mL, respectively); similarly, Cr levels were 13 times higher (p < 0.0001) at a 2-year follow-up than before surgery (Cr, means: 1.69 and 0.13 ng/mL, respectively). Ni concentrations (0.42 and 0.78 ng/mL) were not significantly different (p = 0.16), even if they increased 86% after surgery. In the RRS patients, an inverse correlation was found between Co and Cr concentrations and length of follow-up (Co: r = -0.64, p = 0.0096; Cr: r= -0.45, p = 0.08). The serum levels of Co and Cr were not significantly different between RRS (Co: 1.04 ng/mL and Cr: 1.69 ng/mL) and BHR (Co: 1.39 ng/mL and Cr: 2.30 ng/mL) patients at 2 years (p = 0.95 and 0.26 for Co and Cr, respectively). Our results showed that RRS patients achieved an excellent clinical outcome with limited metal ion release. PMID:24962936

  2. South Pole-Aitken Basin: Evidence for Post-Basin Resurfacing from Lunar Orbiter Laser Altimeter (LOLA) Data

    NASA Astrophysics Data System (ADS)

    Head, J. W.; Fassett, C.; Kadish, S.; Smith, D. E.; Zuber, M. T.; Neumann, G. A.; Mazarico, E.

    2010-12-01

    The lunar farside South Pole-Aitken Basin is the largest and oldest documented basin on the Moon and is thus of interest from the point of view of the scale of production of impact melt at large basin-event sizes and its ring structure and potential depth of sampling at such a large diameter. We used new LOLA data from the Lunar Reconnaissance Orbiter 1) to characterize the basin interior topography, 2) to assess the nature of the nearby and relatively pristine Orientale basin and compare it to the SPA interior, and 3) to compile a new global crater database of all lunar craters ≥20 km in diameter and to assess the population of impact craters superposed on the SPA interior and exterior. We find that impact crater size-frequency distribution plots show that the exterior of the SPA basin is similar to the most heavily cratered regions of the Moon, but that the interior of the basin has a deficiency of craters in the 20-64 km diameter crater range. One interpretation of these data is that some resurfacing process (or processes) has modified the superposed crater population. Among the candidates are 1) impact crater proximity weathering/degradation by adjacent (e.g., Apollo) and nearby (e.g., Orientale) impact basin ejecta, 2) volcanic resurfacing by early non-mare volcanism, cryptomaria and/or maria, and 3) viscous relaxation removing crater topography. We consider viscous relaxation of crater topography to be the least likely due to the wavelength dependence of the process (rim-crests should be preserved and thus detected in our crater counts). Careful analysis of the impact ejecta thickness radial decay suggests that it is an important resurfacing mechanism within a basin radius from the rim crest, but is unlikely to be sufficient to explain the observed deficiency. Morphometric analysis of impact craters, modeling, and simulations of volcanic flooding suggest that the deficiency may be related to the patchy distribution of cryptomaria, suspected from mineralogic

  3. On dynamic gas ablation from spherical galaxies

    NASA Astrophysics Data System (ADS)

    Nepveu, M.

    1981-05-01

    Two-dimensional, time dependent gas dynamic calculations are presented on the transonic motion of galaxies through a cluster medium. Lea and De Young's (1976) calculations are extended to include violent behavior in the center. On time scales of 10 to the 8th yr, galaxies in clusters can already lose a significant fraction of their gaseous content (up to 50% has been found in the calculations). This dynamic ablation occurs through rarefaction rather than shock heating. Explosions in spherical galaxies become effective as mechanisms for gas removal only if the galaxy moves with respect to its surroundings. Speculations are made on stripping of spiral galaxies (moving head-on in a cluster); the Gunn and Gott (1972) stripping formula is put to doubt. A method is suggested to obtain information on the state of motion of field galaxies.

  4. Birmingham Hip Resurfacing: A Single Surgeon Series Reported at a Minimum of 10 Years Follow-Up.

    PubMed

    Mehra, Akshay; Berryman, Fiona; Matharu, Gulraj S; Pynsent, Paul B; Isbister, Eric S

    2015-07-01

    We report outcomes on 120 Birmingham Hip Resurfacings (BHRs) (mean age 50 years) at a minimum of ten-years follow-up. Cases were performed by one surgeon and included his learning curve. Six hips were revised, with no revisions for infection, dislocation, or adverse reaction to metal debris. Ten-year survival was 94.2% (95% confidence interval (CI) 88.8%-98.7%) for all revisions and 96.1% (95% CI 91.5%-99.8%) for revisions for aseptic loosening. Gender (P = 0.463) and head size (P = 0.114) did not affect revision risk. Mean post-operative Harris hip score was 84.0. Contrary to previous independent reports, good outcomes into the second decade were achieved with the BHR in both men and women. Longer term follow-up will confirm whether these promising outcomes in women continue. PMID:25769743

  5. Resurfacing history of the northern plains of Mars based on geologic mapping of Mars Global Surveyor data

    USGS Publications Warehouse

    Tanaka, K.L.; Skinner, J.A.; Hare, T.M.; Joyal, T.; Wenker, A.

    2003-01-01

    Geologic mapping of the northern plains of Mars, based on Mars Orbiter Laser Altimeter topography and Viking and Mars Orbiter Camera images, reveals new insights into geologic processes and events in this region during the Hesperian and Amazonian Periods. We propose four successive stages of lowland resurfacing likely related to the activity of near-surface volatiles commencing at the highland-lowland boundary (HLB) and progressing to lower topographic levels as follows (highest elevations indicated): Stage 1, upper boundary plains, Early Hesperian, <-2.0 to -2.9 km; Stage 2, lower boundary plains and outflow channel dissection, Late Hesperian, <-2.7 to -4.0 km; Stage 3, Vastitas Borealis Formation (VBF) surface, Late Hesperian to Early Amazonian, <-3.1 to -4.1 km; and Stage 4, local chaos zones, Early Amazonian, <-3.8 to -5.0 km. At Acidalia Mensa, Stage 2 and 3 levels may be lower (<-4.4 and -4.8 km, respectively). Contractional ridges form the dominant structure in the plains and developed from near the end of the Early Hesperian to the Early Amazonian. Geomorphic evidence for a northern-plains-filling ocean during Stage 2 is absent because one did not form or its evidence was destroyed by Stage 3 resurfacing. Remnants of possible Amazonian dust mantles occur on top of the VBF. The north polar layered deposits appear to be made up of an up to kilometer-thick lower sequence of sandy layers Early to Middle Amazonian in age overlain by Late Amazonian ice-rich dust layers; both units appear to have outliers, suggesting that they once were more extensive.

  6. Resurfacing history of the northern plains of Mars based on geologic mapping of Mars Global Surveyor data

    NASA Astrophysics Data System (ADS)

    Tanaka, K. L.; Skinner, J. A.; Hare, T. M.; Joyal, T.; Wenker, A.

    2003-04-01

    Geologic mapping of the northern plains of Mars, based on Mars Orbiter Laser Altimeter topography and Viking and Mars Orbiter Camera images, reveals new insights into geologic processes and events in this region during the Hesperian and Amazonian Periods. We propose four successive stages of lowland resurfacing likely related to the activity of near-surface volatiles commencing at the highland-lowland boundary (HLB) and progressing to lower topographic levels as follows (highest elevations indicated): Stage 1, upper boundary plains, Early Hesperian, <-2.0 to -2.9 km; Stage 2, lower boundary plains and outflow channel dissection, Late Hesperian, <-2.7 to -4.0 km; Stage 3, Vastitas Borealis Formation (VBF) surface, Late Hesperian to Early Amazonian, <-3.1 to -4.1 km; and Stage 4, local chaos zones, Early Amazonian, <-3.8 to -5.0 km. At Acidalia Mensa, Stage 2 and 3 levels may be lower (<-4.4 and -4.8 km, respectively). Contractional ridges form the dominant structure in the plains and developed from near the end of the Early Hesperian to the Early Amazonian. Geomorphic evidence for a northern-plains-filling ocean during Stage 2 is absent because one did not form or its evidence was destroyed by Stage 3 resurfacing. Remnants of possible Amazonian dust mantles occur on top of the VBF. The north polar layered deposits appear to be made up of an up to kilometer-thick lower sequence of sandy layers Early to Middle Amazonian in age overlain by Late Amazonian ice-rich dust layers; both units appear to have outliers, suggesting that they once were more extensive.

  7. Chronic cough and dyspnea in ice hockey players after an acute exposure to combustion products of a faulty ice resurfacer.

    PubMed

    Kahan, Erika S; Martin, Ubaldo J; Spungen, Steve; Ciccolella, David; Criner, Gerard J

    2007-01-01

    The aim of this study was to characterize pulmonary function and radiologic testing in ice hockey players after exposure to combustion products of a faulty ice resurfacer. Our patients were 16 previously healthy hockey players who developed chronic cough and dyspnea after exposure. Symptom questionnaires, pulmonary function tests (PFTs), bronchoprovocation testing, cardiopulmonary exercise testing, high-resolution computed tomography (CT) imaging, and impulse oscillometry (IOS) were all used. A normal group was used for PFTs and IOS controls. Patients had onset of cough within 72 h of exposure. Ninety-two percent complained of dyspnea, 75% chest pain, and 33% hemoptysis. Eight percent were initially hospitalized for their symptoms. Eighty-five percent were treated with systemic steroids and 39% with inhaled bronchodilators. Six months postexposure, 54% complained of cough and 46% complained of dyspnea on exertion. All patients had normal PFTs; 8.3% had a significant bronchodilator response. All had normal exercise tests (mean VO2max = 90 +/- 3% predicted) and chest CTs. With IOS, 80% had a significant bronchodilator response (decreased resistance > 12% and SD score > 1; mean change = 21.1 +/- 9.9%, mean SD score = 3.1 +/- 2.5). No correlation existed between changes in resistance or reactance and spirometric values. Patient symptoms correlated significantly with bronchodilator response on IOS resistance (R=0.61, p=0.03). More than 50% of patients exposed to the combustion products of a faulty ice resurfacer remained symptomatic six months after exposure. Despite persistence of symptoms, conventional pulmonary function tests and radiologic evaluation did not reveal airway abnormalities. IOS showed evidence of increased airway resistance and small-airway disease, which correlated with patient symptoms. PMID:17294334

  8. Radiofrequency Ablation to Prevent Sudden Cardiac Death

    PubMed Central

    Atoui, Moustapha; Gunda, Sampath; Lakkireddy, Dhanunjaya; Mahapatra, Srijoy

    2015-01-01

    Radiofrequency ablation may prevent or treat atrial and ventricular arrhythmias. Since some of these arrhythmias are associated with sudden cardiac death, it has been hypothesized that ablation may prevent sudden death in certain cases. We performed a literature search to better understand under which circumstances ablation may prevent sudden death and found little randomized data demonstrating the long-term effects of ablation. Current literature shows that ablation clearly prevents symptoms of arrhythmia and may reduce the incidence of sudden cardiac death in select patients, although data does not indicate improved mortality. Ongoing clinical trials are needed to better define the role of ablation in preventing sudden cardiac death. PMID:26306130

  9. Thermal Response of In Vivo Human Skin to Fractional Radiofrequency Microneedle Device

    PubMed Central

    Manuskiatti, Woraphong; Pattanaprichakul, Penvadee; Inthasotti, Siriluk; Sitthinamsuwan, Panitta; Hanamornroongruang, Suchanan; Wanitphakdeedecha, Rungsima; Chu-ongsakol, Sorawuth

    2016-01-01

    Background. Fractional radiofrequency microneedle system (FRMS) is a novel fractional skin resurfacing system. Data on thermal response to this fractional resurfacing technique is limited. Objectives. To investigate histologic response of in vivo human skin to varying energy settings and pulse stacking of a FRMS in dark-skinned subjects. Methods. Two female volunteers who were scheduled for abdominoplasty received treatment with a FRMS with varying energy settings at 6 time periods including 3 months, 1 month, 1 week, 3 days, 1 day, and the time immediately before abdominoplasty. Biopsy specimens were analyzed using hematoxylin and eosin (H&E), Verhoeff-Van Gieson (VVG), colloidal iron, and Fontana-Masson stain. Immunohistochemical study was performed by using Heat Shock Protein 70 (HSP70) antibody and collagen III monoclonal antibody. Results. The average depth of radiofrequency thermal zone (RFTZ) ranged from 100 to 300 μm, correlating with energy levels. Columns of cell necrosis and collagen denaturation followed by inflammatory response were initially demonstrated, with subsequent increasing of mucin at 1 and 3 months after treatment. Immunohistochemical study showed positive stain with HSP70. Conclusion. A single treatment with a FRMS using appropriate energy setting induces neocollagenesis. This wound healing response may serve as a mean to improve the appearance of photodamaged skin and atrophic scars. PMID:27247943

  10. Leonid meteor ablation, energy exchange and trail morphology

    SciTech Connect

    Zinn, John; Judd, O'Dean P.; ReVelle, D. O.

    2002-01-01

    This paper describes theoretical model studies of the interaction of Leonid meteoroids with the earth's atmosphere. Subject to some modest-to-strenuous approximations we compute the rates of ablation and deceleration, energy deposition, and terminal altitudes of the meteors as functions of their initial mass and bulk density, velocity, trajectory entry angle, drag coefficient, heat of ablation, and an ablation energy transfer fraction. We find that the dominant energy deposition in the atmosphere is associated with the stopping of the ablated meteor particles and vapor by the surrounding air. Then having computed the energy deposition rates versus altitude we compute the hydrodynamic and radiative expansion of the hot wake material in the radial direction, along with the associated air chemistry. From the computed results we can then plot two-dimensional temperature contours -- as functions of the instantaneous distance behind the meteor and radial distance from the center of the wake, at various altitudes along the meteor's path. We also compute the rates of emission of radiation and the radiative efficiency, and discuss comparisons with observations.

  11. Conjunction of Endocardial and Coronary Venous System Mapping to Ablate Ventricular Arrhythmias

    PubMed Central

    Wo, Hung-Ta; Yeh, Jih-Kai; Chang, Po-Cheng; Wen, Ming-Shien; Wang, Chun-Chieh; Chou, Chung-Chuan; Yeh, San-Jou

    2016-01-01

    Background Ablation of idiopathic ventricular arrhythmias (VAs) with epicardial or intramural origins is technically challenging. Herein, we have described the successful ablation of left VAs via the coronary venous system (CVS) in conjunction with endocardial map guided by three-dimensional electroanatomical map in six patients. Methods Out of a total consecutive 84 patients with symptomatic idiopathic VAs, radiofrequency ablation via the CVS was performed on six patients (7%). Furthermore, we reviewed patient records and electrophysiologic studies with respect to clinical characteristics. Results Activation map was conducted in 5 patients, and the earliest activation sites were identified within the CVS. The preceding times to the onset of QRS complex were longer than those at the earliest endocardial sites (36.2 ± 5.6 ms vs. 14.2 ± 6.4 ms, p = 0.02, n = 5). Spiky fractionated long-duration potentials were recorded at the successful ablation sites in all 5 patients. The other patient received pacemapping only because of few spontaneous VAs during the procedure, and the best pacemap spot was found within the CVS. Irrigated catheters were required in 4 out of 6 patients because VAs were temporarily suppressed with regular ones. Conclusions Idiopathic VAs can be ablated via the CVS in conjunction with endocardial mapping. Additionally, spiky fractionated long-duration potential can function as a clue to identify the good ablation site.

  12. Thermal response and ablation characteristics of lightweight ceramic ablators

    SciTech Connect

    Tran, H.K.; Rasky, D.J.; Esfahani, L.

    1994-11-01

    This paper presents the thermal performance and ablation characteristics of the newly developed lightweight ceramic ablators (LCAs) in a supersonic, high-enthalpy convective environment. Lightweight ceramic ablators were recently conceived and developed at NASA Ames using low-density ceramic or carbon fibrous matrices as substrates for main structural support and organic resins as fillers. These LCAs were successfully produced with densities ranging from approximately 0.224 to 1.282 g/cu cm. Several infiltrants with different char yields were used to study the effect on surface recession. Tests were conducted in the NASA Ames arc-jet facilities. Material thermal performance was evaluated at cold-wall heat fluxes from 113.5 to 1634 W/sq cm, and stagnation pressures of 0.018 to 0.331 atm. Conventional ablators such as SLA-561, Avcoat 5026-39HC, MA-25S, and balsa wood were tested at the same heat fluxes for direct comparison. Surface temperature was measured using optical pyrometers, and the recession rates were obtained from the high-speed films. In-depth temperature data were obtained to determine the thermal penetration depths and conductivity. Preliminary results indicated that most LCAs performed comparably to or better than conventional ablators. At low flux levels (less than 454 W/sq cm), the addition of silicon carbide and polymethyl methacrylate significantly improved the ablation performance of silica substrates. The carbon-based LCAs were the most mass-efficient at high flux levels (greater than 454 W/sq cm). 16 refs.

  13. Fragmentation and ablation during entry

    SciTech Connect

    Canavan, G.H.

    1997-09-01

    This note discusses objects that both fragment and ablate during entry, using the results of previous reports to describe the velocity, pressure, and fragmentation of entering objects. It shows that the mechanisms used there to describe the breakup of non-ablating objects during deceleration remain valid for most ablating objects. It treats coupled fragmentation and ablation during entry, building on earlier models that separately discuss the entry of objects that are hard, whose high heat of ablation permits little erosion, and those who are strong whose strength prevents fragmentation, which are discussed in ``Radiation from Hard Objects,`` ``Deceleration and Radiation of Strong, Hard, Asteroids During Atmospheric Impact,`` and ``Meteor Signature Interpretation.`` This note provides a more detailed treatment of the further breakup and separation of fragments during descent. It replaces the constraint on mass per unit area used earlier to determine the altitude and magnitude of peak power radiation with a detailed analytic solution of deceleration. Model predictions are shown to be in agreement with the key features of numerical calculations of deceleration. The model equations are solved for the altitudes of maximum radiation, which agree with numerical integrations. The model is inverted analytically to infer object size and speed from measurements of peak power and altitude to provide a complete model for the approximate inversion of meteor data.

  14. Laser ablation studies of concrete

    SciTech Connect

    Savina, M.; Xu, Z.; Wang, Y.; Reed, C.; Pellin, M.

    1999-10-20

    Laser ablation was studied as a means of removing radioactive contaminants from the surface and near-surface regions of concrete. The authors present the results of ablation tests on cement and concrete samples using a 1.6 kW pulsed Nd:YAG laser with fiber optic beam delivery. The laser-surface interaction was studied using cement and high density concrete as targets. Ablation efficiency and material removal rates were determined as functions of irradiance and pulse overlap. Doped samples were also ablated to determine the efficiency with which surface contaminants were removed and captured in the effluent. The results show that the cement phase of the material melts and vaporizes, but the aggregate portion (sand and rock) fragments. The effluent consists of both micron-size aerosol particles and chunks of fragmented aggregate material. Laser-induced optical emission spectroscopy was used to analyze the surface during ablation. Analysis of the effluent showed that contaminants such as cesium and strontium were strongly segregated into different regions of the particle size distribution of the aerosol.

  15. Femtosecond laser ablation of enamel

    NASA Astrophysics Data System (ADS)

    Le, Quang-Tri; Bertrand, Caroline; Vilar, Rui

    2016-06-01

    The surface topographical, compositional, and structural modifications induced in human enamel by femtosecond laser ablation is studied. The laser treatments were performed using a Yb:KYW chirped-pulse-regenerative amplification laser system (560 fs and 1030 nm) and fluences up to 14 J/cm2. The ablation surfaces were studied by scanning electron microscopy, grazing incidence x-ray diffraction, and micro-Raman spectroscopy. Regardless of the fluence, the ablation surfaces were covered by a layer of resolidified material, indicating that ablation is accompanied by melting of hydroxyapatite. This layer presented pores and exploded gas bubbles, created by the release of gaseous decomposition products of hydroxyapatite (CO2 and H2O) within the liquid phase. In the specimen treated with 1-kHz repetition frequency and 14 J/cm2, thickness of the resolidified material is in the range of 300 to 900 nm. The micro-Raman analysis revealed that the resolidified material contains amorphous calcium phosphate, while grazing incidence x-ray diffraction analysis allowed detecting traces of a calcium phosphate other than hydroxyapatite, probably β-tricalcium phosphate Ca3), at the surface of this specimen. The present results show that the ablation of enamel involves melting of enamel's hydroxyapatite, but the thickness of the altered layer is very small and thermal damage of the remaining material is negligible.

  16. Study of polymer ablation products obtained by ultraviolet laser ablation — inductively coupled plasma atomic emission spectrometry

    NASA Astrophysics Data System (ADS)

    Todolí, J.-L.; Mermet, J.-M.

    1998-10-01

    A study of the nature of aerosols following polymer laser ablation was performed. A glass sample was used for comparison. Aerosol fractions were analyzed by using simple methods based on transport efficiency and filters. Three different tube lengths, i.e. 4, 29 and 54 m, were inserted between the ablation cell and the inductively coupled plasma atomic emission spectrometry (ICP-AES) injector. For the glass sample, 10 elements were studied. Only Na and K exhibited different results as the particle size, i.e. tube length, was varied. The polymers used were poly(vinyl chloride), PVC, and poly(ethylene), PE. Three elements (Ca, Ti and Sn) under different chemical forms were measured. Unlike Ti and Sn the ablated aerosol particle size (mass) seemed to depend on the Ca chemical form. Another PVC sample containing 11 elements was also studied. Na, Al and C exhibited a different behavior with particle size with respect to the remaining elements. Then, the carbon signal was studied after a 0.3 μm pore size filter had been placed between the ablation cell and the ICP torch. The results indicated that carbon was mainly present under gaseous form and particles smaller than 0.3 μm size. The analysis of the aerosol gaseous phase by thermal desorption GC-MS confirmed the presence of polymer volatile thermal degradation products. These results explained why carbon could not be applied as an efficient internal standard.

  17. Laser Ablation as Treatment Strategy for Medically Refractory Dominant Insular Epilepsy – Therapeutic and Functional Considerations

    PubMed Central

    Hawasli, Ammar H.; Bandt, S. Kathleen; Hogan, R. Edward; Werner, Nicole; Leuthardt, Eric C.

    2014-01-01

    Since its introduction to neurosurgery in 2008, laser ablative techniques have been largely confined to the management of unresectable tumors. Application of this technology for the management of focal epilepsy in the adult population has not been fully explored. Given that nearly 1,000,000 Americans live with medically refractory epilepsy and current surgical techniques only address a fraction of epileptic pathologies, additional therapeutic options are needed. We report the successful treatment of dominant insular epilepsy in a 53 year-old male with minimally-invasive laser ablation complicated by mild verbal and memory deficits. We also report neuropsychological test data on this patient before surgery and at 8-months after the ablation procedure. This account represents the first reported successful patient outcome of laser ablation as an effective treatment option for medically refractory post-stroke epilepsy in an adult. PMID:25359500

  18. Implementation of Radiation, Ablation, and Free Energy Minimization Modules for Coupled Simulations of Hypersonic Flow

    NASA Technical Reports Server (NTRS)

    Gnoffo, Peter A.; Johnston, Christopher O.; Thompson, Richard A.

    2009-01-01

    A description of models and boundary conditions required for coupling radiation and ablation physics to a hypersonic flow simulation is provided. Chemical equilibrium routines for varying elemental mass fraction are required in the flow solver to integrate with the equilibrium chemistry assumption employed in the ablation models. The capability also enables an equilibrium catalytic wall boundary condition in the non-ablating case. The paper focuses on numerical implementation issues using FIRE II, Mars return, and Apollo 4 applications to provide context for discussion. Variable relaxation factors applied to the Jacobian elements of partial equilibrium relations required for convergence are defined. Challenges of strong radiation coupling in a shock capturing algorithm are addressed. Results are presented to show how the current suite of models responds to a wide variety of conditions involving coupled radiation and ablation.

  19. The effect of magnetic fields on the products of laser ablation

    NASA Astrophysics Data System (ADS)

    Musaev, O. R.; Sutter, E. A.; Wrobel, J. M.; Kruger, M. B.

    2016-02-01

    Structures of gold nanoparticles were formed by laser ablation of bulk gold immersed in water. An excimer laser with a wavelength of 351 nm and a pulse energy of 7 mJ was used. Ablation was performed in two configurations: without and with an external 0.2 T magnetic field parallel to the ablation plume. Both configurations result in structures that include chains of aggregated nanoparticles, but to different degrees. Ablation in a magnetic field results in a higher fraction of spherical nanoparticles and shorter nanowires, compared to the nanowire networks formed in the absence of the field. This can be explained by magnetic confinement of the plasma during plume expansion. A model explaining nanowire formation and dependence on fluence and magnetic field is proposed.

  20. A Review of Mitral Isthmus Ablation

    PubMed Central

    Wong, Kelvin CK; Betts, Timothy R

    2012-01-01

    Mitral isthmus ablation forms part of the electrophysiologist’s armoury in the catheter ablation treatment of atrial fibrillation. It is well recognised however, that mitral isthmus ablation is technically challenging and incomplete ablation may be pro-arrhythmic, leading some to question its role. This article first reviews the evidence for the use of adjunctive mitral isthmus ablation and its association with the development of macroreentrant perimitral flutter. It then describes the practical techniques of mitral isthmus ablation, with particular emphasis on the assessment of bi-directional mitral isthmus block. The anatomy of the mitral isthmus is also discussed in order to understand the possible obstacles to successful ablation. Finally, novel techniques which may facilitate mitral isthmus ablation are reviewed. PMID:22912536

  1. Femtosecond lasers for machining of transparent, brittle materials: ablative vs. non-ablative femtosecond laser processing

    NASA Astrophysics Data System (ADS)

    Hendricks, F.; Matylitsky, V. V.

    2016-03-01

    This paper focuses on precision machining of transparent materials by means of ablative and non-ablative femtosecond laser processing. Ablation technology will be compared with a newly developed patent pending non-ablative femtosecond process, ClearShapeTM, using the Spectra-Physics Spirit industrial femtosecond laser.

  2. Microwave ablation of hepatocellular carcinoma

    PubMed Central

    Poggi, Guido; Tosoratti, Nevio; Montagna, Benedetta; Picchi, Chiara

    2015-01-01

    Although surgical resection is still the optimal treatment option for early-stage hepatocellular carcinoma (HCC) in patients with well compensated cirrhosis, thermal ablation techniques provide a valid non-surgical treatment alternative, thanks to their minimal invasiveness, excellent tolerability and safety profile, proven efficacy in local disease control, virtually unlimited repeatability and cost-effectiveness. Different energy sources are currently employed in clinics as physical agents for percutaneous or intra-surgical thermal ablation of HCC nodules. Among them, radiofrequency (RF) currents are the most used, while microwave ablations (MWA) are becoming increasingly popular. Starting from the 90s’, RF ablation (RFA) rapidly became the standard of care in ablation, especially in the treatment of small HCC nodules; however, RFA exhibits substantial performance limitations in the treatment of large lesions and/or tumors located near major heat sinks. MWA, first introduced in the Far Eastern clinical practice in the 80s’, showing promising results but also severe limitations in the controllability of the emitted field and in the high amount of power employed for the ablation of large tumors, resulting in a poor coagulative performance and a relatively high complication rate, nowadays shows better results both in terms of treatment controllability and of overall coagulative performance, thanks to the improvement of technology. In this review we provide an extensive and detailed overview of the key physical and technical aspects of MWA and of the currently available systems, and we want to discuss the most relevant published data on MWA treatments of HCC nodules in regard to clinical results and to the type and rate of complications, both in absolute terms and in comparison with RFA. PMID:26557950

  3. Thermal Ablation of Lung Tumors

    PubMed Central

    Sonntag, P. David; Hinshaw, J. Louis; Lubner, Meghan G.; Brace, Christopher L.; Lee, Fred T.

    2011-01-01

    Lung cancer remains the leading cause of cancer death in the United States, accounting for an estimated 29% of cancer deaths in 2009.1 Pneumonectomy or lobectomy with hilar and mediastinal lymph node sampling is the gold standard treatment and offers the best option for cure of stage 1/2 nonsmall cell lung cancer (NSCLC).2 Unfortunately, only 15% of patients present with stage 1/2 disease, and many of these patients do not meet the pulmonary physiologic guidelines for lobar resection.3 In addition to lung cancer, pulmonary metastases are present in 25% to 30% of patients dying from all types of cancer.4 For some patients with oligometastatic pulmonary disease, metastectomy is associated with an improvement in survival.5 External beam radiation traditionally has been offered as the alternative to surgical resection for NSCLC or pulmonary metastatic disease. Unfortunately, the 5-year survival following radiation for stage 1 and 2 NSCLC remains low at 15% to 20%, with local recurrence being the most common mode of failure.6,7 Thermal ablation offers an intriguing therapeutic option to increase local tumor control and survival in patients with early stage NSCLC or with limited metastatic disease from nonlung primaries who are not surgical candidates because of poor cardiopulmonary reserve, anatomic constraints limiting resection, failure of traditional therapies, or refusal of operative approaches. Thermal ablation has been shown to be effective in treating tumors in bone, kidney, and liver.8–11 Most preclinical and clinical trials have focused on demonstrating the feasibility of three modalities for pulmonary thermal ablation, namely radiofrequency (RF) ablation, microwave (MW) ablation, and cryoablation. This article discusses the unique challenges of performing thermal ablation in lung tissue and reviews the current literature regarding RF, MW, and cryoablation in the lung. PMID:21377589

  4. Microwave ablation of hepatocellular carcinoma.

    PubMed

    Poggi, Guido; Tosoratti, Nevio; Montagna, Benedetta; Picchi, Chiara

    2015-11-01

    Although surgical resection is still the optimal treatment option for early-stage hepatocellular carcinoma (HCC) in patients with well compensated cirrhosis, thermal ablation techniques provide a valid non-surgical treatment alternative, thanks to their minimal invasiveness, excellent tolerability and safety profile, proven efficacy in local disease control, virtually unlimited repeatability and cost-effectiveness. Different energy sources are currently employed in clinics as physical agents for percutaneous or intra-surgical thermal ablation of HCC nodules. Among them, radiofrequency (RF) currents are the most used, while microwave ablations (MWA) are becoming increasingly popular. Starting from the 90s', RF ablation (RFA) rapidly became the standard of care in ablation, especially in the treatment of small HCC nodules; however, RFA exhibits substantial performance limitations in the treatment of large lesions and/or tumors located near major heat sinks. MWA, first introduced in the Far Eastern clinical practice in the 80s', showing promising results but also severe limitations in the controllability of the emitted field and in the high amount of power employed for the ablation of large tumors, resulting in a poor coagulative performance and a relatively high complication rate, nowadays shows better results both in terms of treatment controllability and of overall coagulative performance, thanks to the improvement of technology. In this review we provide an extensive and detailed overview of the key physical and technical aspects of MWA and of the currently available systems, and we want to discuss the most relevant published data on MWA treatments of HCC nodules in regard to clinical results and to the type and rate of complications, both in absolute terms and in comparison with RFA. PMID:26557950

  5. Transhemangioma Ablation of Hepatocellular Carcinoma

    SciTech Connect

    Pua, Uei

    2012-12-15

    Radiofrequency ablation (RFA) is a well-established treatment modality in the treatment of early hepatocellular carcinoma (HCC) [1]. Safe trajectory of the RFA probe is crucial in decreasing collateral tissue damage and unwarranted probe transgression. As a percutaneous technique, however, the trajectory of the needle is sometimes constrained by the available imaging plane. The presence of a hemangioma beside an HCC is uncommon but poses the question of safety related to probe transgression. We hereby describe a case of transhemangioma ablation of a dome HCC.

  6. Laser ablation of human tooth

    NASA Astrophysics Data System (ADS)

    Franklin, Sushmita R.; Chauhan, P.; Mitra, A.; Thareja, R. K.

    2005-05-01

    We report the measurements of ablation threshold of human tooth in air using photo-thermal deflection technique. A third harmonic (355nm) of Nd:YAG (yttrium aluminum garnet) laser was used for irradiation and a low power helium neon laser as a probe beam. The experimental observations of ablation threshold in conjunction with theoretical model based on heat conduction equations for simulating the interaction of a laser radiation with a calcified tissue are used to estimate the absorption coefficient of human tooth.

  7. Tektite ablation - Some confirming calculations.

    NASA Technical Reports Server (NTRS)

    O'Keefe, J. A., III; Silver, A. D.; Cameron, W. S.; Adams , E. W.; Warmbrod, J. D.

    1973-01-01

    The calculation of tektite ablation has been redone, taking into account transient effects, internal radiation, melting and nonequilibrium vaporization of the glass, and the drag effect of the flanges. It is found that the results confirm the earlier calculations of Chapman and his group and of Adams and his co-workers. The general trend of the results is not sensitive to reasonable changes of the physical parameters. The ablation is predominantly by melting rather than by vaporization at all velocities up to 11 km/sec; this is surprising in view of the lack of detectable melt flow in most tektites. Chemical effects have not been considered.

  8. Ablative Therapies for Barrett's Esophagus

    PubMed Central

    Garman, Katherine S.; Shaheen, Nicholas J.

    2011-01-01

    Barrett's esophagus has gained increased clinical attention because of its association with esophageal adenocarcinoma, a cancer with increasing incidence and poor survival rates. The goals of ablating Barrett's esophagus are to decrease esophageal cancer rates and to improve overall survival and quality of life. Different techniques have been developed and tested for their effectiveness eradicating Barrett's epithelium. This review assesses the literature associated with different ablative techniques. The safety and efficacy of different techniques are discussed. This review concludes with recommendations for the clinician, including specific strategies for patient care decisions for patients with Barrett's esophagus with varying degrees of dysplasia. PMID:21373836

  9. Laser ablation based fuel ignition

    DOEpatents

    Early, J.W.; Lester, C.S.

    1998-06-23

    There is provided a method of fuel/oxidizer ignition comprising: (a) application of laser light to a material surface which is absorptive to the laser radiation; (b) heating of the material surface with the laser light to produce a high temperature ablation plume which emanates from the heated surface as an intensely hot cloud of vaporized surface material; and (c) contacting the fuel/oxidizer mixture with the hot ablation cloud at or near the surface of the material in order to heat the fuel to a temperature sufficient to initiate fuel ignition. 3 figs.

  10. Laser ablation based fuel ignition

    DOEpatents

    Early, James W.; Lester, Charles S.

    1998-01-01

    There is provided a method of fuel/oxidizer ignition comprising: (a) application of laser light to a material surface which is absorptive to the laser radiation; (b) heating of the material surface with the laser light to produce a high temperature ablation plume which emanates from the heated surface as an intensely hot cloud of vaporized surface material; and (c) contacting the fuel/oxidizer mixture with the hot ablation cloud at or near the surface of the material in order to heat the fuel to a temperature sufficient to initiate fuel ignition.

  11. Atrial Fibrillation Ablation and Stroke.

    PubMed

    Aagaard, Philip; Briceno, David; Csanadi, Zoltan; Mohanty, Sanghamitra; Gianni, Carola; Trivedi, Chintan; Nagy-Baló, Edina; Danik, Stephan; Barrett, Conor; Santoro, Francesco; Burkhardt, J David; Sanchez, Javier; Natale, Andrea; Di Biase, Luigi

    2016-05-01

    Catheter ablation has become a widely available and accepted treatment to restore sinus rhythm in atrial fibrillation patients who fail antiarrhythmic drug therapy. Although generally safe, the procedure carries a non-negligible risk of complications, including periprocedural cerebral insults. Uninterrupted anticoagulation, maintenance of an adequate ACT during the procedure, and measures to avoid and detect thrombus build-up on sheaths and atheters during the procedure, appears useful to reduce the risk of embolic events. This is a review of the incidence, mechanisms, impact, and methods to reduce catheter ablation related cerebral insults. PMID:27150179

  12. Plasma acceleration processes in an ablative pulsed plasma thruster

    SciTech Connect

    Koizumi, Hiroyuki; Noji, Ryosuke; Komurasaki, Kimiya; Arakawa, Yoshihiro

    2007-03-15

    Plasma acceleration processes in an ablative pulsed plasma thruster (APPT) were investigated. APPTs are space propulsion options suitable for microspacecraft, and have recently attracted much attention because of their low electric power requirements and simple, compact propellant system. The plasma acceleration mechanism, however, has not been well understood. In the present work, emission spectroscopy, high speed photography, and magnetic field measurements are conducted inside the electrode channel of an APPT with rectangular geometry. The successive images of neutral particles and ions give us a comprehensive understanding of their behavior under electromagnetic acceleration. The magnetic field profile clarifies the location where the electromagnetic force takes effect. As a result, it is shown that high density, ablated neutral gas stays near the propellant surface, and only a fraction of the neutrals is converted into plasma and electromagnetically accelerated, leaving the residual neutrals behind.

  13. Radiofrequency ablation during continuous saline infusion can extend ablation margins

    PubMed Central

    Ishikawa, Toru; Kubota, Tomoyuki; Horigome, Ryoko; Kimura, Naruhiro; Honda, Hiroki; Iwanaga, Akito; Seki, Keiichi; Honma, Terasu; Yoshida, Toshiaki

    2013-01-01

    AIM: To determine whether fluid injection during radiofrequency ablation (RFA) can increase the coagulation area. METHODS: Bovine liver (1-2 kg) was placed on an aluminum tray with a return electrode affixed to the base, and the liver was punctured by an expandable electrode. During RFA, 5% glucose; 50% glucose; or saline fluid was infused continuously at a rate of 1.0 mL/min through the infusion line connected to the infusion port. The area and volume of the thermocoagulated region of bovine liver were determined after RFA. The Joule heat generated was determined from the temporal change in output during the RFA experiment. RESULTS: No liquid infusion was 17.3 ± 1.6 mL, similar to the volume of a 3-cm diameter sphere (14.1 mL). Mean thermocoagulated volume was significantly larger with continuous infusion of saline (29.3 ± 3.3 mL) than with 5% glucose (21.4 ± 2.2 mL), 50% glucose (16.5 ± 0.9 mL) or no liquid infusion (17.3 ± 1.6 mL). The ablated volume for RFA with saline was approximately 1.7-times greater than for RFA with no liquid infusion, representing a significant difference between these two conditions. Total Joule heat generated during RFA was highest with saline, and lowest with 50% glucose. CONCLUSION: RFA with continuous saline infusion achieves a large ablation zone, and may help inhibit local recurrence by obtaining sufficient ablation margins. RFA during continuous saline infusion can extend ablation margins, and may be prevent local recurrence. PMID:23483097

  14. Percutaneous Tumor Ablation with Radiofrequency

    PubMed Central

    Wood, Bradford J.; Ramkaransingh, Jeffrey R.; Fojo, Tito; Walther, McClellan M.; Libutti, Stephen K.

    2008-01-01

    BACKGROUND Radiofrequency thermal ablation (RFA) is a new minimally invasive treatment for localized cancer. Minimally invasive surgical options require less resources, time, recovery, and cost, and often offer reduced morbidity and mortality, compared with more invasive methods. To be useful, image-guided, minimally invasive, local treatments will have to meet those expectations without sacrificing efficacy. METHODS Image-guided, local cancer treatment relies on the assumption that local disease control may improve survival. Recent developments in ablative techniques are being applied to patients with inoperable, small, or solitary liver tumors, recurrent metachronous hereditary renal cell carcinoma, and neoplasms in the bone, lung, breast, and adrenal gland. RESULTS Recent refinements in ablation technology enable large tumor volumes to be treated with image-guided needle placement, either percutaneously, laparoscopically, or with open surgery. Local disease control potentially could result in improved survival, or enhanced operability. CONCLUSIONS Consensus indications in oncology are ill-defined, despite widespread proliferation of the technology. A brief review is presented of the current status of image-guided tumor ablation therapy. More rigorous scientific review, long-term follow-up, and randomized prospective trials are needed to help define the role of RFA in oncology. PMID:11900230

  15. Modern Advances in Ablative TPS

    NASA Technical Reports Server (NTRS)

    Venkatapathy, Ethiraj

    2013-01-01

    Topics covered include: Physics of Hypersonic Flow and TPS Considerations. Destinations, Missions and Requirements. State of the Art Thermal Protection Systems Capabilities. Modern Advances in Ablative TPS. Entry Systems Concepts. Flexible TPS for Hypersonic Inflatable Aerodynamic Decelerators. Conformal TPS for Rigid Aeroshell. 3-D Woven TPS for Extreme Entry Environment. Multi-functional Carbon Fabric for Mechanically Deployable.

  16. Photochemical Ablation of Organic Solids

    NASA Astrophysics Data System (ADS)

    Garrison, Barbara

    2004-03-01

    As discovered by Srinivasan in 1982, irradiation of materials by far UV laser light can lead to photochemical ablation, a process distinct from normal thermal ablation in which the laser primarily heats the material. A versatile mesoscopic model for molecular dynamics simulations of the laser ablation phenomena is presented. The model incorporates both the thermal and photochemical events, that is, both heating of the system and UV induced bond-cleavage followed by abstraction and radical-radical recombination reactions. The results from the simulations are compared to experimental data and the basic physics and chemistry for each irradiation regime are discussed. Initial results from polymer ablation simulations will be presented. L. V. Zhigilei, P. B. S. Kodali and B. J. Garrison, J. Phys. Chem. B, 102, 2845-2853 (1998); L. V. Zhigilei and B. J. Garrison, Journal of Applied Physics, 88, 1281-1298 (2000). Y. G. Yingling, L. V. Zhigilei and B. J. Garrison, J. Photochemistry and Photobiology A: Chemistry, 145, 173-181 (2001); Y. G. Yingling and B. J. Garrison, Chem. Phys. Lett., 364, 237-243 (2002).

  17. Electron Beam Ablation of Metals

    NASA Astrophysics Data System (ADS)

    Kovaleski, S. D.; Gilgenbach, R. M.; Rintamaki, J. I.; Ang, L. K.; Spindler, H. L.; Cohen, W. E.; Lau, Y. Y.; Lash, J. S.

    1996-10-01

    An experiment has recently been devised for material ablation using a channelspark electron beam. The ultimate goal of this experiment is to deposit thin films by electron beam ablation. The channelspark is a pseudospark device developed by Forschungszentrum Karlsruhe (G. Muller, C. Schultheiss, Proc. of Beams, 2, 833(1994)) for production of high current, low energy electron beams. The channelspark has the following operating parameters: a 15-20kV accelerating potential and measured source current of <2000A. Initial experiments have concentrated on characterizing ion-focused electron beam current transport through the necessary background fill gas (typically 5-50 mTorr of Argon). Ablation of Al, Fe, and Ti is being studied with spectroscopy and electron beam current diagnostics. Physical beam target damage is also being investigated and compared to laser ablated targets. Simulations of electron transport and energy deposition are being conducted via the ITS-TIGER code (Sandia Report No. SAND 91-1634) developed at Sandia National Laboratory.

  18. Photophysical ablation of porous silicon

    NASA Astrophysics Data System (ADS)

    Aksenov, Valerii P.; Mikhailova, G. N.

    2004-07-01

    Laser ablation of porous silicon as a function of laser wavelength and width of silicon nanowires was studied in our experiments. The time-resolved evolution of the cloud of the porous silicon particles produced by laser ablation is studied in situ by the analysis of the kinetics of photoluminescence signal. The laser ablation of porous silicon produced by pulses of 532 nm or 337 nm radiation with addition of synchronized power pulses of 1064 nm radiation. The cloud of the nanometer-sized silicon crystallites had the high enhancement of luminescence quantum efficiency in the red region of spectra. The slow PL kinetics component, which is due to the localized carriers, decays on a millisecond time scale. The squeezed electron-hole plasma heating by IR-laser radiation may produce a damage of silicon nanowires. The fragments of nanowires in cloud must be smaller, than the critical length. The energy of excitation of e-h pair in fragment with contribution of longitude quantum modes must be lower than energy of the excited photons. Particles with lesser length don't absorb excited laser radiation and don't damage. For this case we may speak about the quantum mechanism of laser ablation of nanowires.

  19. A safe zone for acetabular component position in metal-on-metal hip resurfacing arthroplasty: winner of the 2012 HAP PAUL award.

    PubMed

    Liu, Fei; Gross, Thomas P

    2013-08-01

    A safe zone for acetabular component positioning in hip resurfacing (RAIL: Relative Acetabular Inclination Limit) was calculated based on implant size and acetabular inclination angle (AIA). For AIA below the RAIL, there were no adverse wear failures or dislocations, and only 1% of cases with ion levels above 10 μg/L. Other than high inclination angle and small bearing size, female gender was the only other factor that correlated with high ion levels in the multivariate analysis. Seven hundred sixty-one hip resurfacing cases are included in this study. The UCLA activity score, femoral shaft angle, body mass index, weight, American Society of Anesthesiologists score, combined range of motion, diagnosis, age, gender, implant brand, AIA, bearing size, and duration of implantation were analyzed to determine the potential risk factors for elevated metal ion levels. These findings apply to sub hemispheric metal-on-metal bearings with similar coverage arcs as the Biomet and Corin hip resurfacing brands. Additional problems may occur when these bearings are connected with trunions on stems for total hip arthroplasty. PMID:23540536

  20. Esophageal papilloma: Flexible endoscopic ablation by radiofrequency

    PubMed Central

    del Genio, Gianmattia; del Genio, Federica; Schettino, Pietro; Limongelli, Paolo; Tolone, Salvatore; Brusciano, Luigi; Avellino, Manuela; Vitiello, Chiara; Docimo, Giovanni; Pezzullo, Angelo; Docimo, Ludovico

    2015-01-01

    Squamous papilloma of the esophagus is a rare benign lesion of the esophagus. Radiofrequency ablation is an established endoscopic technique for the eradication of Barrett esophagus. No cases of endoscopic ablation of esophageal papilloma by radiofrequency ablation (RFA) have been reported. We report a case of esophageal papilloma successfully treated with a single session of radiofrequency ablation. Endoscopic ablation of the lesion was achieved by radiofrequency using a new catheter inserted through the working channel of endoscope. The esophageal ablated tissue was removed by a specifically designed cup. Complete ablation was confirmed at 3 mo by endoscopy with biopsies. This case supports feasibility and safety of as a new potential indication for BarrxTM RFA in patients with esophageal papilloma. PMID:25789102

  1. Microwave Ablation Compared with Radiofrequency Ablation for Breast Tissue in an Ex Vivo Bovine Udder Model

    SciTech Connect

    Tanaka, Toshihiro; Westphal, Saskia; Isfort, Peter; Braunschweig, Till; Penzkofer, Tobias Bruners, Philipp; Kichikawa, Kimihiko; Schmitz-Rode, Thomas Mahnken, Andreas H.

    2012-08-15

    Purpose: To compare the effectiveness of microwave (MW) ablation with radiofrequency (RF) ablation for treating breast tissue in a nonperfused ex vivo model of healthy bovine udder tissue. Materials and Methods: MW ablations were performed at power outputs of 25W, 35W, and 45W using a 915-MHz frequency generator and a 2-cm active tip antenna. RF ablations were performed with a bipolar RF system with 2- and 3-cm active tip electrodes. Tissue temperatures were continuously monitored during ablation. Results: The mean short-axis diameters of the coagulation zones were 1.34 {+-} 0.14, 1.45 {+-} 0.13, and 1.74 {+-} 0.11 cm for MW ablation at outputs of 25W, 35W, and 45W. For RF ablation, the corresponding values were 1.16 {+-} 0.09 and 1.26 {+-} 0.14 cm with electrodes having 2- and 3-cm active tips, respectively. The mean coagulation volumes were 2.27 {+-} 0.65, 2.85 {+-} 0.72, and 4.45 {+-} 0.47 cm{sup 3} for MW ablation at outputs of 25W, 35W, and 45W and 1.18 {+-} 0.30 and 2.29 {+-} 0.55 cm{sup 3} got RF ablation with 2- and 3-cm electrodes, respectively. MW ablations at 35W and 45W achieved significantly longer short-axis diameters than RF ablations (P < 0.05). The highest tissue temperature was achieved with MW ablation at 45W (P < 0.05). On histological examination, the extent of the ablation zone in MW ablations was less affected by tissue heterogeneity than that in RF ablations. Conclusion: MW ablation appears to be advantageous with respect to the volume of ablation and the shape of the margin of necrosis compared with RF ablation in an ex vivo bovine udder.

  2. Does surface wettability influence the friction and wear of large-diameter CoCrMo alloy hip resurfacings?

    PubMed

    Curran, Sarah; Hoskin, Tom; Williams, Sarah; Scholes, Susan C; Kinbrum, Amy; Unsworth, Anthony

    2013-08-01

    The role of surface tension in the lubrication of metal-on-metal (CoCrMo alloy) hip resurfacings has been investigated to try to explain why all metal joints fail to be lubricated with simple water-based lubricants (sodium carboxymethyl cellulose), which have similar rheology to synovial fluid, but are lubricated with the same fluid with the addition of a proportion of bovine serum. As part of this study, surfactants, in the form of detergents, when added to carboxymethyl cellulose, have been shown to produce a predominantly fluid-film lubrication mechanism with friction even lower than the biological lubricant containing serum. Friction factors were reduced by 80% when a detergent was added to the lubricant. It is considered that the failure of the water-based fluids to generate fluid-film lubrication is due to the fact that 'boundary slip' takes place where the fluid does not fully attach to the bounding solid surfaces as assumed in Reynolds' equation, thereby drawing in less lubricant than predicted from hydrodynamic theory. The addition of surfactants either in the form of natural materials such as serum or in the form of detergent reduces surface tension and helps the water-based lubricant to attach more fully to the bounding surfaces resulting in more fluid entrainment and thicker fluid-film formation. This was confirmed by up to 70% lower wear being found when these joints were lubricated in a detergent solution rather than 25% bovine serum. PMID:23852389

  3. In vivo evaluation of edge-loading in metal-on-metal hip resurfacing patients with pseudotumours

    PubMed Central

    Kwon, Y-M.; Mellon, S. J.; Monk, P.; Murray, D. W.; Gill, H. S.

    2012-01-01

    Objectives Pseudotumours (abnormal peri-prosthetic soft-tissue reactions) following metal-on-metal hip resurfacing arthroplasty (MoMHRA) have been associated with elevated metal ion levels, suggesting that excessive wear may occur due to edge-loading of these MoM implants. This study aimed to quantify in vivo edge-loading in MoMHRA patients with and without pseudotumours during functional activities. Methods The duration and magnitude of edge-loading in vivo was quantified during functional activities by combining the dynamic hip joint segment contact force calculated from the three-dimensional (3D) motion analysis system with the 3D reconstruction of orientation of the acetabular component and each patient’s specific hip joint centre, based on CT scans. Results Edge-loading in the hips with pseudotumours occurred with a four-fold increase in duration and magnitude of force compared with the hips without pseudotumours (p = 0.02). Conclusions The study provides the first in vivo evidence to support that edge-loading is an important mechanism that leads to localised excessive wear (edge-wear), with subsequent elevation of metal ion levels in MoMHRA patients with pseudotumours. PMID:23610670

  4. Iron isotopic evidence for convective resurfacing of recycled arc-front mantle beneath back-arc basins

    NASA Astrophysics Data System (ADS)

    Nebel, O.; Arculus, R. J.; Sossi, P. A.; Jenner, F. E.; Whan, T. H. E.

    2013-11-01

    observations suggest sub-arc convective flow transports melt-exhausted and metasomatized wedge mantle into deeper mantle regions. Reciprocally, asthenospheric, fertile mantle may supply back-arc ridges distal to the trench by shallow, lateral mantle ingress, insinuating initial wedge mantle depletion in its back-arc region. Here we show that light Fe isotope compositions of the Central Lau Spreading Centre located in the Lau back-arc basin on the farside of the Tonga-Kermadec arc are indicative for derivation from a modified arc-front mantle with elemental and Nd-isotopic memory of former slab fluid addition. We propose that this shallow wedge material has been transported from the sub-arc mantle to the back-arc either convectively or in a buoyant diapir. This implies that melt-depleted mantle in subduction zones is, at least in parts, recycled in a resurfacing loop. This can explain the depletion in back-arc regions, and the progressively depleted nature of island arc sources in maturing arc systems.

  5. Effect of diamond burs on process and damage involving in vitro dental resurfacing of a restorative porcelain

    NASA Astrophysics Data System (ADS)

    Yin, Ling; Han, Yi-Gang; Song, Xiao-Fei; Wang, Hui

    2007-09-01

    This work reports on the effect of diamond burs with coarse, medium and fine grit sizes and nickel or chromium coatings on in vitro dental resurfacing of a restorative porcelain. Process parameters such as tangential and normal forces, surface roughness, surface damage and morphology were studied as a function of removal rate using the different burs. At the lower removal rate, the differences for both the tangential and the normal forces were not significant among the coarse, medium and fine burs. However, when the porcelain was removed at the higher removal rate, both the tangential and the normal forces were markedly higher using the fine bur than those using the medium and coarse burs. Surface roughness values in terms of arithmetic mean and maximum roughness decreased significantly with a decrease in diamond grit size. The scale of surface damage in the form of brittle fracture decreased, and more transitions from brittle removal to ductile flow were observed when using finer grit diamond burs. In a comparison of the diamond bur topographies before and after dental finishing, it was found that minimal wear occurred on the nickel-coated coarse diamond bur, while minor abrasive wear occurred on the nickel-coated medium and chromium-coated fine burs.

  6. Convergent ablation measurements with gas-filled rugby hohlraum on OMEGA

    NASA Astrophysics Data System (ADS)

    Casner, A.; Jalinaud, T.; Galmiche, D.

    2016-03-01

    Convergent ablation experiments with gas-filled rugby hohlraum were performed for the first time on the OMEGA laser facility. A time resolved 1D streaked radiography of capsule implosion is acquired in the direction perpendicular to hohlraum axis, whereas a 2D gated radiography is acquired at the same time along the hohlraum axis on a x-ray framing camera. The implosion trajectory has been measured for various kinds of uniformly doped ablators, including germanium-doped and silicon-doped polymers (CH), at two different doping fraction (2% and 4% at.). Our experiments aimed also at measuring the implosion performance of laminated capsules. A laminated ablator is constituted by thin alternate layers of un-doped and doped CH. It has been previously shown in planar geometry that laminated ablators could mitigate Rayleigh Taylor growth at ablation front. Our results confirm that the implosion of a capsule constituted with a uniform or laminated ablator behaves similarly, in accordance with post-shot simulations performed with the CEA hydrocode FCI2.

  7. Representative sampling using single-pulse laser ablation withinductively coupled plasma mass spectroscopy

    SciTech Connect

    Liu, Haichen; Mao, Xianglei; Russo, Richard E.

    2001-04-02

    Single pulse laser ablation sampling with inductively coupled plasma mass spectrometry (ICP-MS) was assessed for accurate chemical analysis. Elemental fractionation (e.g. Pb/U), the quantity of ablated mass (crater volume), ICP-MS intensity and the particle contribution (spike signal) during single pulse ablation of NIST 610 glass were investigated. Pb/U fractionation significantly changed between the first and second laser pulse and showed strong irradiance dependence. The Pb/U ratio obtained by the first pulse was usually higher than that of the second pulse, with the average value close to the representative level. Segregation during laser ablation is proposed to explain the composition change between the first and second pulse. Crater volume measurements showed that the second pulse produced significantly more ablated mass. A roll-off of the crater depth occurred at {approx}750 GW/cm{sup 2}. The absolute ICP-MS intensity from the second pulse showed no correlation with crater depth. Particle induced spikes on the transit signal showed irradiance and elemental species dependence.

  8. Characterization of degradation fragments released by arc-induced ablation of polymers in air

    NASA Astrophysics Data System (ADS)

    Aminlashgari, Nina; Becerra, Marley; Hakkarainen, Minna

    2016-02-01

    Polymers exposed to high intensity arc plasmas release material in a process called arc-induced ablation. In order to investigate the degradation fragments released due to this process, two different polymeric materials, poly(oxymethylene) copolymer (POM-C) and poly(methyl methacrylate) (PMMA), were exposed to a transient, high-power arc plasma in air. A small fraction of the ablated material drifting away from the arcing volume was deposited on a fixed glass substrate during the total duration of a 2 kA ac current semicycle. In addition, another fraction of the released material was deposited on a second moving substrate to obtain a time-resolved streak ‘image’ of the arc-induced ablation process. For the first time, mass spectra of degradation fragments produced by arc-induced ablation were obtained from the material deposited on the substrates by using laser desorption ionization time-of-flight mass spectrometry (LDI-ToF-MS). It was found that oligomers with mean molecular weight ranging between 400 and 600 Da were released from the surface of the studied polymers. The obtained spectra suggest that the detected degradation fragments of POM could be released by random chain scission of the polymer backbone. In turn, random chain scission and splitting-off the side groups are suggested as the main chemical mechanism leading to the release of PMMA fragments under arc-induced ablation.

  9. Laser Ablation Propulsion A Study

    NASA Astrophysics Data System (ADS)

    Irfan, Sayed A.; Ugalatad, Akshata C.

    Laser Ablation Propulsion (LAP) will serve as an alternative propulsion system for development of microthrusters. The principle of LAP is that when a laser (pulsed or continuous wave) with sufficient energy (more than the vaporization threshold energy of material) is incident on material, ablation or vaporization takes place which leads to the generation of plasma. The generated plasma has the property to move away from the material hence pressure is generated which leads to the generation of thrust. Nowadays nano satellites are very common in different space and defence applications. It is important to build micro thruster which are useful for orienting and re-positioning small aircraft (like nano satellites) above the atmosphere. modelling of LAP using MATLAB and Mathematica. Schematic is made for the suitable optical configuration of LAP. Practical experiments with shadowgraphy and self emission techniques and the results obtained are analysed taking poly (vinyl-chloride) (PVC) as propellant to study the

  10. Laser Ablation Molecular Isotopic Spectrometry

    NASA Astrophysics Data System (ADS)

    Russo, Richard E.; Bol'shakov, Alexander A.; Mao, Xianglei; McKay, Christopher P.; Perry, Dale L.; Sorkhabi, Osman

    2011-02-01

    A new method of performing optical isotopic analysis of condensed samples in ambient air and at ambient pressure has been developed: Laser Ablation Molecular Isotopic Spectrometry (LAMIS). The technique uses radiative transitions from molecular species either directly vaporized from a sample or formed by associative mechanisms of atoms or ions in a laser ablation plume. This method is an advanced modification of a known atomic emission technique called laser-induced breakdown spectroscopy (LIBS). The new method — LAMIS — can determine not only chemical composition but also isotopic ratios of elements in the sample. Isotopic measurements are enabled by significantly larger isotopic shifts found in molecular spectra relative to atomic spectra. Analysis can be performed from a distance and in real time. No sample preparation or pre-treatment is required. Detection of the isotopes of hydrogen, boron, carbon, and oxygen are discussed to illustrate the technique.

  11. Electron Beam Ablation and Deposition

    NASA Astrophysics Data System (ADS)

    Kovaleski, S. D.; Gilgenbach, R. M.; Ang, L. K.; Lau, Y. Y.

    1997-11-01

    Ablation of fused silica, titanium nitride, and boron nitride with a channel spark electron beam is being studied. The channel spark is a low energy (15-20kV), high current (1600A) electron beam source developed at KFK(G. Muller and C. Schultheiss, Proc. of Beams `94, Vol. II, p833). This is a pseudospark device which operates in the ion focused regime of electron beam transport. For this reason, a low pressure (10-15mTorr of Ar) background gas is used to provide electron beam focusing. Plume composition and excitation has been studied via optical emission spectroscopy. Ablation has also been imaged photographically. Electron density gradients and densities are being studied through laser deflection. Film deposition experiments are also being performed. Electron transport and energy deposition in metals are being simulated in the ITS-TIGER code(Sandia Report No. SAND 91-1634).

  12. Artificial meteor ablation studies: Olivine

    NASA Technical Reports Server (NTRS)

    Blanchard, M. B.; Cunningham, G. G.

    1973-01-01

    Artificial meteor ablation was performed on a Mg-rich olivine sample using an arc-heated plasma of ionized air. Experimental conditions simulated a meteor traveling about 12 km/sec at an altitude of 70 km. The mineral content of the original olivine sample was 98% olivine (including traces of olivine alteration products) and 2% chromite. Forsterite content of the original olivine was Fo-89. After ablation, the forsterite content had increased to Fo-94 in the recrystallized olivine. In addition, lamella-like intergrowths of magnetite were prevalent constituents. Wherever magnetite occurred, there was an increase in Mg and a corresponding decrease in Fe for the recrystallized olivine. The Allende fusion crust consisted of a recrystallized olivine, which was more Mg-rich and Fe-deficient than the original meteorite's olivine, and abundant magnetite grains. Although troilite and pentlandite were the common opaque mineral constituents in this meteorite, magnetite was the principal opaque mineral found in the fusion crust.

  13. Investigations of the Cavitation and Damage Thresholds of Histotripsy and Applications in Targeted Tissue Ablation

    NASA Astrophysics Data System (ADS)

    Vlaisavljevich, Eli

    Histotripsy is a noninvasive ultrasound therapy that controls acoustic cavitation to mechanically fractionate soft tissue. This dissertation investigates the physical thresholds to initiate cavitation and produce tissue damage in histotripsy and factors affecting these thresholds in order to develop novel strategies for targeted tissue ablation. In the first part of this dissertation, the effects of tissue properties on histotripsy cavitation thresholds and damage thresholds were investigated. Results demonstrated that the histotripsy shock scattering threshold using multi-cycle pulses increases in stiffer tissues, while the histotripsy intrinsic threshold using single-cycle pulses is independent of tissue stiffness. Further, the intrinsic threshold slightly decreases with lower frequencies and significantly decreases with increasing temperature. The effects of tissue properties on the susceptibility to histotripsy-induced tissue damage were also investigated, demonstrating that stiffer tissues are more resistant to histotripsy. Two strategies were investigated for increasing the effectiveness of histotripsy for the treatment of stiffer tissues, with results showing that thermal preconditioning may be used to alter tissue susceptibility to histotripsy and that lower frequency treatments may increase the efficiency of histotripsy tissue ablation due to enhanced bubble expansion. In the second part of this dissertation, the feasibility of using histotripsy for targeted liver ablation was investigated in an intact in vivo porcine model, with results demonstrating that histotripsy was capable of non-invasively creating precise lesions throughout the entire liver. Additionally, a tissue selective ablation approach was developed, where histotripsy completely fractionated the liver tissue surrounding the major hepatic vessels and gallbladder while being self-limited at the boundaries of these critical structures. Finally, the long-term effects of histotripsy liver

  14. Caries selective ablation: the handpiece

    NASA Astrophysics Data System (ADS)

    Hennig, Thomas; Rechmann, Peter; Holtermann, Andreas

    1995-05-01

    Caries selective ablation is fixed to a window of fluences predicted by the ablation thresholds of carious and healthy dentin, respectively. The aim of the study was to develop a dental handpiece which guarantees homogeneous fluence at the irradiated tooth surface. Furthermore the point of treatment should be cooled down without energy losses due to the cooling system. We suggest the direct coupling of the laser radiation into a laminar stream of liquid, which acts in turn as a lengthened beam guide. The impacts of the laser radiation and of the cooling medium fall exactly into the same point. Hot ablation debris is removed out of the crater by the flush of the water jet. Fluences are constant if the handpiece is used in contact mode or at a distance. Normally the surface of a bare fiber working in contact mode is destroyed after a few shots. Coupling the laser radiation into a stream of liquid prevents this destruction. Putting together the benefits of this special handpiece short overall treatment times seem to be possible. High average power can be applied to the tooth without the threat of thermal damage. Furthermore no time consuming cutting of the fiber prolongs the treatment time.

  15. Excimer laser ablation of ferrites

    NASA Astrophysics Data System (ADS)

    Tam, A. C.; Leung, W. P.; Krajnovich, D.

    1991-02-01

    Laser etching of ferrites was previously done by scanning a focused continuous-wave laser beam on a ferrite sample in a chemical environment. We study the phenomenon of photo-ablation of Ni-Zn or Mn-Zn ferrites by pulsed 248-nm KrF excimer laser irradiation. A transfer lens system is used to project a grating pattern of a mask irradiated by the pulsed KrF laser onto the ferrite sample. The threshold fluence for ablation at the ferrite surface is about 0.3 J/cm2. A typical fluence of 1 J/cm2 is used. The etched grooves produced are typically 20-50 μm wide, with depths achieved as deep as 70 μm . Groove straightness is good as long as a sharp image is projected onto the sample surface. The wall angle is steeper than 60 degrees. Scanning electron microscopy of the etched area shows a ``glassy'' skin with extensive microcracks and solidified droplets being ejected that is frozen in action. We found that this skin can be entirely removed by ultrasonic cleaning. A fairly efficient etching rate of about 10 nm/pulse for a patterned area of about 2 mm×2 mm is obtained at a fluence of 1 J/cm2. This study shows that projection excimer laser ablation is useful for micromachining of ferrite ceramics, and indicates that a hydrodynamic sputtering mechanism involving droplet emission is a cause of material removal.

  16. Image-guided ablation for hepatocellular carcinoma.

    PubMed

    Lencioni, Riccardo; Crocetti, Laura

    2013-01-01

    Image-guided ablation is accepted as the best therapeutic choice for patients with early-stage hepatocellular carcinoma (HCC) when surgical options-including resection and transplantation-are precluded. The term image-guided tumor ablation is defined as the direct application of chemical substances or sources of energy to a focal tumor in an attempt to achieve eradication or substantial tumor destruction. Over the past 25 years, several methods for local tumor destruction have been developed and clinically tested. Radiofrequency ablation (RFA) has shown superior anticancer effect and greater survival benefit with respect to the seminal percutaneous technique, ethanol injection, in meta-analyses of randomized controlled trials, and is currently established as the standard ablative modality. Nevertheless, novel thermal and nonthermal techniques for tumor ablation-including microwave ablation and irreversible electroporation-seem to have potential to improve the efficacy of RFA and are currently undergoing clinical investigation. PMID:22941021

  17. Time-resolved studies of particle effects in laser ablation inductively coupled plasma-mass spectrometry

    SciTech Connect

    Perdian, D.; Bajic, S.; Baldwin, D.; Houk, R.

    2007-11-13

    Time resolved signals in laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) are studied to determine the influence of experimental parameters on ICP-induced fractionation effects. Differences in sample composition and morphology, i.e., ablating brass, glass, or dust pellets, have a profound effect on the time resolved signal. Helium transport gas significantly decreases large positive signal spikes arising from large particles in the ICP. A binder for pellets also reduces the abundance and amplitude of spikes in the signal. MO{sup +} ions also yield signal spikes, but these MO{sup +} spikes generally occur at different times from their atomic ion counterparts.

  18. Fractional CO2 laser treatment for a skin graft.

    PubMed

    Stephan, Farid E; Habre, Maya B; Helou, Josiane F; Tohme, Roland G; Tomb, Roland R

    2016-01-01

    Skin grafts are widely used in reconstructive and plastic surgery, leaving an inevitable scar appearance on the body, affecting the quality of life of the patients. Fractional ablative lasers have become a leading procedure for the treatment of acne and burn scars. We report a case of a skin graft showing excellent improvement in overall appearance after three sessions of fractional CO2 laser. The undamaged tissue left between the microthermal treatment zones is responsible of collagen formation and reepithelialization. Remodeling and collagen formation are observed even 6 months after a fractional CO2 laser session. PMID:26052811

  19. Catheter ablation of persistent atrial fibrillation: The importance of substrate modification

    PubMed Central

    Letsas, Konstantinos P; Efremidis, Michael; Sgouros, Nikolaos P; Vlachos, Konstantinos; Asvestas, Dimitrios; Sideris, Antonios

    2015-01-01

    Accumulating data have shown that elimination of atrial fibrillation (AF) sources should be the goal in persistent AF ablation. Pulmonary vein isolation, linear lesions and complex fractionated atrial electrograms (CFAEs) ablation have shown limited efficacy in patients with persistent AF. A combined approach using voltage, CFAEs and dominant frequency (DF) mapping may be helpful for the identification of AF sources and subsequent focal substrate modification. The fibrillatory activity is maintained by intramural reentry centered on fibrotic patches. Voltage mapping may assist in the identification of fibrotic areas. Stable rotors display the higher DF and possibly drive AF. Furthermore, the single rotor is usually consistent with organized AF electrograms without fractionation. It is therefore quite possible that rotors are located at relatively “healthy islands” within the patchy fibrosis. This is supported by the fact that high DF sites have been negatively correlated to the amount of fibrosis. CFAEs are located in areas adjacent to high DF. In conclusion, patchy fibrotic areas displaying the maximum DF along with high organization index and the lower fractionation index are potential targets of ablation. Prospective studies are required to validate the efficacy of substrate modification in left atrial ablation outcomes. PMID:25810810

  20. Inductively Coupled Plasma: Fundamental Particle Investigations with Laser Ablation and Applications in Magnetic Sector Mass Spectrometry

    SciTech Connect

    Saetveit, Nathan Joe

    2008-01-01

    Particle size effects and elemental fractionation in laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) are investigated with nanosecond and femtosecond laser ablation, differential mobility analysis, and magnetic sector ICP-MS. Laser pulse width was found to have a significant influence on the LA particle size distribution and the elemental composition of the aerosol and thus fractionation. Emission from individual particles from solution nebulization, glass, and a pressed powder pellet are observed with high speed digital photography. The presence of intact particles in an ICP is shown to be a likely source of fractionation. A technique for the online detection of stimulated elemental release from neural tissue using magnetic sector ICP-MS is described. Detection limits of 1 μg L-1 or better were found for P, Mn, Fe, Cu, and Zn in a 60 μL injection in a physiological saline matrix.

  1. Quantification of the effect of electrical and thermal parameters on radiofrequency ablation for concentric tumour model of different sizes.

    PubMed

    Jamil, Muhammad; Ng, E Y K

    2015-07-01

    Radiofrequency ablation (RFA) has been increasingly used in treating cancer for multitude of situations in various tissue types. To perform the therapy safely and reliably, the effect of critical parameters needs to be known beforehand. Temperature plays an important role in the outcome of the therapy and any uncertainties in temperature assessment can be lethal. This study presents the RFA case of fixed tip temperature where we've analysed the effect of electrical conductivity, thermal conductivity and blood perfusion rate of the tumour and surrounding normal tissue on the radiofrequency ablation. Ablation volume was chosen as the characteristic to be optimised and temperature control was achieved via PID controller. The effect of all 6 parameters each having 3 levels was quantified with minimum number of experiments harnessing the fractional factorial characteristic of Taguchi's orthogonal arrays. It was observed that as the blood perfusion increases the ablation volume decreases. Increasing electrical conductivity of the tumour results in increase of ablation volume whereas increase in normal tissue conductivity tends to decrease the ablation volume and vice versa. Likewise, increasing thermal conductivity of the tumour results in enhanced ablation volume whereas an increase in thermal conductivity of the surrounding normal tissue has a debilitating effect on the ablation volume and vice versa. With increase in the size of the tumour (i.e., 2-3cm) the effect of each parameter is not linear. The parameter effect varies with change in size of the tumour that is manifested by the different gradient observed in ablation volume. Most important is the relative insensitivity of ablation volume to blood perfusion rate for smaller tumour size (2cm) that is also in accordance with the previous results presented in literature. These findings will provide initial insight for safe, reliable and improved treatment planning perceptively. PMID:25965014

  2. Laser Ablation of Alumina in Water

    SciTech Connect

    Musaev, O.; Midgley, A; Wrobel, J; Kruger, M

    2010-01-01

    Bulk {alpha}-alumina immersed in distilled water was ablated by pulsed UV laser radiation. The resulting colloidal solution contained micron and submicron size particles. X-ray diffraction and Raman spectra of the ablated and original material are similar. Hence, most of the ablated material is {alpha}-alumina. From transmission electron microscope images, most of the submicron and all of the micron-sized particles have sharp edges and do not have spherical shapes, indicating that the dominant ablation mechanism is due to crack propagation. Some spherical particles of diameter less than 100 nm are observed, indicating that they were formed from the liquid state.

  3. Ablative therapies in renal cell carcinoma.

    PubMed

    Chan, A A; Ahrar, K; Matin, S F

    2011-09-01

    We reviewed the use of ablative therapies in the management of renal cell carcinoma. We performed a PubMed search of the English language literature using the keywords "ablation" and "renal carcinoma." Pertinent articles specific to the technologic advancement of ablative therapy and clinical outcomes were selected for review. Intermediate-term oncologic outcomes of cryoablation and radiofrequency ablation are acceptable but are not quite as good as for surgical excision based nearly all on retrospective studies. No randomized studies have been performed comparing excisional and ablative therapies. Careful selection of patients and tumor characteristics results in improved outcomes. Diagnostic biopsy for tissue confirmation is mandatory and should even be considered post therapy after 6-12 months in patients with a concern about recurrence. Ablative therapies are associated with decreased morbidity, less severe complication rates, and excellent preservation of renal function in comparison with surgical excision. The majority of recurrences occur early, but long-term surveillance is required as delayed recurrences are also possible and the long-term oncologic efficacy is not yet established. Ablation can be delivered percutaneously or laparoscopically, and the superiority of one over the other remains controversial. The percutaneous approach is more cost effective and causes less perinephric desmoplasia. Nearly all data on ablation are retrospective and, with few exceptions, from single institutions. Ablative therapy is an appealing option for the management of small renal tumors shown to be renal cell carcinoma on biopsy in patients who are unsuitable candidates for surgical extirpation. PMID:21993322

  4. Plasma-mediated ablation of biofilm contamination

    NASA Astrophysics Data System (ADS)

    Guo, Zhixiong; Wang, Xiaoliang; Huang, Huan

    2010-12-01

    Ultra-short pulsed laser removal of thin biofilm contamination on different substrates has been conducted via the use of plasma-mediated ablation. The biofilms were formed using sheep whole blood. The ablation was generated using a 1.2 ps ultra-short pulsed laser with wavelength centered at 1552 nm. The blood contamination was transformed into plasma and collected with a vacuum system. The single line ablation features have been measured. The ablation thresholds of blood contamination and bare substrates were determined. It is found that the ablation threshold of the blood contamination is lower than those of the beneath substrates including the glass slide, PDMS, and human dermal tissues. The ablation effects of different laser parameters (pulse overlap rate and pulse energy) were studied and ablation efficiency was measured. Proper ablation parameters were found to efficiently remove contamination with maximum efficiency and without damage to the substrate surface for the current laser system. Complete removal of blood contaminant from the glass substrate surface and freeze-dried dermis tissue surface was demonstrated by the USP laser ablation with repeated area scanning. No obvious thermal damage was found in the decontaminated glass and tissue samples.

  5. Analysis of iodinated contrast delivered during thermal ablation: is material trapped in the ablation zone?

    NASA Astrophysics Data System (ADS)

    Wu, Po-hung; Brace, Chris L.

    2016-08-01

    Intra-procedural contrast-enhanced CT (CECT) has been proposed to evaluate treatment efficacy of thermal ablation. We hypothesized that contrast material delivered concurrently with thermal ablation may become trapped in the ablation zone, and set out to determine whether such an effect would impact ablation visualization. CECT images were acquired during microwave ablation in normal porcine liver with: (A) normal blood perfusion and no iodinated contrast, (B) normal perfusion and iodinated contrast infusion or (C) no blood perfusion and residual iodinated contrast. Changes in CT attenuation were analyzed from before, during and after ablation to evaluate whether contrast was trapped inside of the ablation zone. Visualization was compared between groups using post-ablation contrast-to-noise ratio (CNR). Attenuation gradients were calculated at the ablation boundary and background to quantitate ablation conspicuity. In Group A, attenuation decreased during ablation due to thermal expansion of tissue water and water vaporization. The ablation zone was difficult to visualize (CNR  =  1.57  ±  0.73, boundary gradient  =  0.7  ±  0.4 HU mm‑1), leading to ablation diameter underestimation compared to gross pathology. Group B ablations saw attenuation increase, suggesting that iodine was trapped inside the ablation zone. However, because the normally perfused liver increased even more, Group B ablations were more visible than Group A (CNR  =  2.04  ±  0.84, boundary gradient  =  6.3  ±  1.1 HU mm‑1) and allowed accurate estimation of the ablation zone dimensions compared to gross pathology. Substantial water vaporization led to substantial attenuation changes in Group C, though the ablation zone boundary was not highly visible (boundary gradient  =  3.9  ±  1.1 HU mm‑1). Our results demonstrate that despite iodinated contrast being trapped in the ablation zone, ablation visibility

  6. Analysis of iodinated contrast delivered during thermal ablation: is material trapped in the ablation zone?

    PubMed

    Wu, Po-Hung; Brace, Chris L

    2016-08-21

    Intra-procedural contrast-enhanced CT (CECT) has been proposed to evaluate treatment efficacy of thermal ablation. We hypothesized that contrast material delivered concurrently with thermal ablation may become trapped in the ablation zone, and set out to determine whether such an effect would impact ablation visualization. CECT images were acquired during microwave ablation in normal porcine liver with: (A) normal blood perfusion and no iodinated contrast, (B) normal perfusion and iodinated contrast infusion or (C) no blood perfusion and residual iodinated contrast. Changes in CT attenuation were analyzed from before, during and after ablation to evaluate whether contrast was trapped inside of the ablation zone. Visualization was compared between groups using post-ablation contrast-to-noise ratio (CNR). Attenuation gradients were calculated at the ablation boundary and background to quantitate ablation conspicuity. In Group A, attenuation decreased during ablation due to thermal expansion of tissue water and water vaporization. The ablation zone was difficult to visualize (CNR  =  1.57  ±  0.73, boundary gradient  =  0.7  ±  0.4 HU mm(-1)), leading to ablation diameter underestimation compared to gross pathology. Group B ablations saw attenuation increase, suggesting that iodine was trapped inside the ablation zone. However, because the normally perfused liver increased even more, Group B ablations were more visible than Group A (CNR  =  2.04  ±  0.84, boundary gradient  =  6.3  ±  1.1 HU mm(-1)) and allowed accurate estimation of the ablation zone dimensions compared to gross pathology. Substantial water vaporization led to substantial attenuation changes in Group C, though the ablation zone boundary was not highly visible (boundary gradient  =  3.9  ±  1.1 HU mm(-1)). Our results demonstrate that despite iodinated contrast being trapped in the ablation zone, ablation visibility

  7. Influence of the stem fixation scenario on load transfer in a hip resurfacing arthroplasty with a biomimetic stem.

    PubMed

    Caouette, C; Bureau, M N; Vendittoli, P-A; Lavigne, M; Nuño, N

    2015-05-01

    Finite element (FE) analysis is a widely used tool for extensive preclinical testing of orthopaedic implants such as hip resurfacing femoral components, including evaluation of different stem fixation scenarios (cementation vs osseointegration, etc.). Most FE models use surface-to-surface contact elements to model the load-bearing interfaces that connect bone, cement and implant and neglect the mechanical effects of phenomena such as residual stresses from bone cement curing. The objective of the current study is to evaluate and quantify the effect of different stem fixation scenarios and related phenomena such as residual stresses from bone cement curing. Four models of a previously clinically available implant (Durom) were used to model different stem fixation scenarios of a new biomimetic stem: a cemented stem, a frictional stem, a partially and completely bonded stem, with and without residual stresses from bone cement curing. For the frictional stem, stem-bone micromotions were increased from 0% to 61% of the available surface subjected to micromotions between 10 and 40μm with the inclusion of residual stresses from bone cement curing. Bonding the stem, even partially, increased stress in the implant at the stem-head junction. Complete bonding of the stem decreased bone strain at step tip, at the cost of increased strain shielding when compared with the frictional stem and partially bonded stem. The increase of micromotions and changes in bone strain highlighted the influence of interfacial conditions on load transfer, and the need for a better modeling method, one capable of assessing the effect of phenomena such as interdigitation and residual stresses from bone cement curing. PMID:25688031

  8. Fine-scale Fractures on the Surface of 433 Eros: Implications for Structural Control and Tectonic Resurfacing of Craters

    NASA Astrophysics Data System (ADS)

    Prockter, L.; Barnouin-Jha, O.

    2003-12-01

    Detailed lineament mapping of the surface of Eros is underway, using high-resolution images obtained by the NEAR-Shoemaker spacecraft during its recent highly successful mission. It is likely that most of the grooves on the asteroid's surface are the result of disturbances of regolith overlying deeper fractures in a coherent substrate, an interpretation that is also plausible for other asteroids and small bodies such as Ida, Gaspra, and Phobos. The presence of numerous single and cross-cutting grooves which may be continuous for several kilometers, implies that the underlying material of which Eros is comprised is largely coherent, and that it is likely not a rubble pile. In addition to grooves, some regions of Eros' surface have a high density of fine-scale lineaments, spaced tens of meters apart. Preexisting structural features have clearly influenced the shapes of some craters, leading to squared-off outlines. Close examination of the surface shows that fine-scale fractures may also be responsible for erasing craters. This type of "tectonic resurfacing" has been inferred on Ganymede, where there are examples of craters strained tens of percent by the formation of fractures and grooves. On Eros, examples can be found of craters that are highly degraded due to numerous parallel fractures running through their interiors. Topographic profiles across these craters show that some are unusually shallow, in part because of regolith infilling, but also possibly as a result of tectonic disruption. We examine the hypothesis that closely-spaced fractures within craters post-date crater formation, since they may not survive the impact process. Such fractures may be the result of reactivation of preexisting structure by later, possibly distant, impact events and may cause subsequent degradation.

  9. Infra-red femtosecond laser ablation: Benefit for LA-ICP-MS elemental analysis?

    NASA Astrophysics Data System (ADS)

    Poitrasson, F.; d'Abzac, F.; Freydier, R.; Seydoux-Guillaume, A.; Chmeleff, J.; Chatel, B.

    2011-12-01

    Femtosecond (fs) laser ablation systems have now been used for about a decade for elemental analysis in chemical and geosciences laboratories. Published studies investigated the influence of various analytical parameters, such as laser pulsewidth, wavelength, energy or ablation duration, on the quality of the analytical data produced by fs Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS). It was rapidly found that under comparable analytical conditions, chemical fractionation effects that may occur during laser-induced particle production, transport and/or decomposition in the ICP-MS plasma torch become negligible in the fs laser ablation regime under 300 fs laser pulsewidth. Another major benefit of fs laser ablation is its restricted matrix-sensitive nature compared to ns laser ablation, thereby facilitating greatly LA-ICP-MS calibration for chemical analysis with a reference material having completely different optical and chemical properties compared to the sample to be analyzed (e.g., a standard glass to calibrate analyses of a phosphate mineral). This effect is particularly remarkable as it can be stated from both UV and IR fs laser ablation studies. Reproducible laser ablations of optical quality quartz can also be produced using such an IR laser. Precise, accurate and reproducible chemical analyses may be obtained using ns laser ablation systems. However, this is achieved under carefully controlled analytical conditions using state of the art ablation cells. Instead, it appears that fs laser ablation is making LA-ICP-MS analyses more reliable. More recently, analytical studies combined with high spatial resolution microscopic techniques allowed us to understand better the nature of fs laser-matter interaction through the direct examination of the laser-induced craters and of the particles produced. These investigations have shown the dominance of mechanical over thermal effects on the solids ablated using a fs laser. Whatever the

  10. Have cementless and resurfacing components improved the medium-term results of hip replacement for patients under 60 years of age?

    PubMed Central

    Mason, James; Baker, Paul; Gregg, Paul J; Porter, Martyn; Deehan, David J; Reed, Mike R

    2015-01-01

    Background and purpose The optimal hip replacement for young patients remains unknown. We compared patient-reported outcome measures (PROMs), revision risk, and implant costs over a range of hip replacements. Methods We included hip replacements for osteoarthritis in patients under 60 years of age performed between 2003 and 2010 using the commonest brand of cemented, cementless, hybrid, or resurfacing prosthesis (11,622 women and 13,087 men). The reference implant comprised a cemented stem with a conventional polyethylene cemented cup and a standard-sized head (28- or 32-mm). Differences in implant survival were assessed using competing-risks models, adjusted for known prognostic influences. Analysis of covariance was used to assess improvement in PROMs (Oxford hip score (OHS) and EQ5D index) in 2014 linked procedures. Results In males, PROMs and implant survival were similar across all types of implants. In females, revision was statistically significantly higher in hard-bearing and/or small-stem cementless implants (hazard ratio (HR) = 4) and resurfacings (small head sizes (< 48 mm): HR = 6; large head sizes (≥ 48 mm): HR = 5) when compared to the reference cemented implant. In component combinations with equivalent survival, women reported significantly greater improvements in OHS with hybrid implants (22, p = 0.006) and cementless implants (21, p = 0.03) (reference, 18), but similar EQ5D index. For men and women, National Health Service (NHS) costs were lowest with the reference implant and highest with a hard-bearing cementless replacement. Interpretation In young women, hybrids offer a balance of good early functional improvement and low revision risk. Fully cementless and resurfacing components are more costly and do not provide any additional benefit for younger patients. PMID:25285617

  11. A Randomized Controlled Trial of Skin Care Protocols for Facial Resurfacing: Lessons Learned from the Plastic Surgery Educational Foundation’s Skin Products Assessment Research Study

    PubMed Central

    Pannucci, Christopher J.; Reavey, Patrick L.; Kaweski, Susan; Hamill, Jennifer B.; Hume, Keith M.; Wilkins, Edwin G.; Pusic, Andrea L.

    2011-01-01

    Background The Skin Products Assessment Research (SPAR) Committee was created by the Plastic Surgery Educational Foundation (PSEF) in 2006. SPAR study aims were to (1) develop an infrastructure for PSEF-conducted, industry sponsored research in facial aesthetic surgery and (2) test the research process by comparing outcomes of the Obagi Nu-Derm System (ONDS) versus conventional therapy as treatment adjuncts for facial resurfacing procedures. Methods The SPAR study was designed as a multi-center, double-blind, randomized controlled trial (RCT). The study was conducted in women with Fitzpatrick type I-IV skin, moderate to severe facial photo damage, and peri-ocular and/or peri-oral fine wrinkles. Patients underwent chemical peel or laser facial resurfacing and were randomized to ONDS or a standard care regimen. The study endpoints were time to re-epithelization, erythema, and pigmentation changes. Results Fifty-six women were enrolled and 82% were followed beyond re-epithelization. There were no significant differences in mean time to re-epithelialization between ONDS and control groups. The ONDS group had a significantly higher median erythema score on day of surgery (after 4 weeks of product use) which did not persist after surgery. Test-retest photo evaluations demonstrated that both inter- and intra-rater reliability were adequate for primary study outcomes. Conclusions In a clinical RCT, we demonstrated no significant difference in time to re-epithelization between patients who used the ONDS or a standard care regimen as an adjunct to facial resurfacing procedures. The SPAR research team has also provided a discussion of future challenges for PSEF sponsored clinical research for readers of this article. PMID:21364435

  12. Preparation of silver nanoparticles in virgin coconut oil using laser ablation

    PubMed Central

    Zamiri, Reza; Azmi, B Z; Sadrolhosseini, Amir Reza; Ahangar, Hossein Abbastabar; Zaidan, A W; Mahdi, M A

    2011-01-01

    Laser ablation of a silver plate immersed in virgin coconut oil was carried out for fabrication of silver nanoparticles. A Nd:YAG laser at wavelengths of 1064 nm was used for ablation of the plate at different times. The virgin coconut oil allowed formation of nanoparticles with well-dispersed, uniform particle diameters that were stable for a reasonable length of time. The particle sizes and volume fraction of nanoparticles inside the solutions obtained at 15, 30, 45 min ablation times were 4.84, 5.18, 6.33 nm and 1.0 × 10−8, 1.6 × 10−8, 2.4 × 10−8, respectively. The presented method for preparation of silver nanoparticles in virgin coconut oil is environmentally friendly and may be considered a green method. PMID:21289983

  13. Fractional vector calculus and fractional Maxwell's equations

    SciTech Connect

    Tarasov, Vasily E.

    2008-11-15

    The theory of derivatives and integrals of non-integer order goes back to Leibniz, Liouville, Grunwald, Letnikov and Riemann. The history of fractional vector calculus (FVC) has only 10 years. The main approaches to formulate a FVC, which are used in the physics during the past few years, will be briefly described in this paper. We solve some problems of consistent formulations of FVC by using a fractional generalization of the Fundamental Theorem of Calculus. We define the differential and integral vector operations. The fractional Green's, Stokes' and Gauss's theorems are formulated. The proofs of these theorems are realized for simplest regions. A fractional generalization of exterior differential calculus of differential forms is discussed. Fractional nonlocal Maxwell's equations and the corresponding fractional wave equations are considered.

  14. Possible Role for Cryoballoon Ablation of Right Atrial Appendage Tachycardia when Conventional Ablation Fails

    PubMed Central

    Kilic, Ayhan

    2015-01-01

    Focal atrial tachycardia arising from the right atrial appendage usually responds well to radiofrequency ablation; however, successful ablation in this anatomic region can be challenging. Surgical excision of the right atrial appendage has sometimes been necessary to eliminate the tachycardia and prevent or reverse the resultant cardiomyopathy. We report the case of a 48-year-old man who had right atrial appendage tachycardia resistant to multiple attempts at ablation with use of conventional radiofrequency energy guided by means of a 3-dimensional mapping system. The condition led to cardiomyopathy in 3 months. The arrhythmia was successfully ablated with use of a 28-mm cryoballoon catheter that had originally been developed for catheter ablation of paroxysmal atrial fibrillation. To our knowledge, this is the first report of cryoballoon ablation without isolation of the right atrial appendage. It might also be an alternative to epicardial ablation or surgery when refractory atrial tachycardia originates from the right atrial appendage. PMID:26175651

  15. Testing and evaluation of light ablation decontamination

    SciTech Connect

    Demmer, R.L.; Ferguson, R.L.

    1994-10-01

    This report details the testing and evaluation of light ablation decontamination. It details WINCO contracted research and application of light ablation efforts by Ames Laboratory. Tests were conducted with SIMCON (simulated contamination) coupons and REALCON (actual radioactive metal coupons) under controlled conditions to compare cleaning effectiveness, speed and application to plant process type equipment.

  16. PULSED LASER ABLATION OF CEMENT AND CONCRETE

    EPA Science Inventory

    Laser ablation was investigated as a means of removing radioactive contaminants from the surface and near-surface regions of concrete from nuclear facilities. We present the results of ablation tests on cement and concrete samples using a pulsed Nd:YAG laser with fiber optic beam...

  17. Percutaneous Local Ablative Therapy for Hepatocellular Carcinoma

    PubMed Central

    Lau, W. Y.; Leung, Thomas W. T.; Yu, Simon C. H.; Ho, Stephen K. W.

    2003-01-01

    Objective To review and compare treatment result for percutaneous local ablative therapy (PLAT) with surgical resection in the treatment of small hepatocellular carcinoma (HCC). Summary Background Data PLAT is indicated for small unresectable HCC localized to the liver. From the use of ethanol to the latest technology of radiofrequency ablation, ablative techniques have been refined and their role in the management of HCC established. This review aims to give an overview of various ablative methods, including their efficacy, indications, and limitations, and also tries to look into the future of clinical trials in PLAT. Methods The authors reviewed recent papers in the English medical literature about the use of local ablative therapy for HCC. Focus was given to the results of treatment in terms of local control, progression-free survival, and overall survival, and to compare treatment results with those of surgery. Results PLAT for small HCC (<5 cm) with thermal ablation (radiofrequency ablation or microwave coagulation) can achieve effective local control of disease and is superior to ethanol injection. Progressive disease in untreated areas is a common reason for failure. Overall progression-free survival is similar to that of surgical resection. Conclusions Thermal ablation gives good local control of small HCC, is superior to ethanol, and may be comparable to surgical resection in long-term outcome. PMID:12560774

  18. Excimer laser ablation of the lens.

    PubMed

    Nanevicz, T M; Prince, M R; Gawande, A A; Puliafito, C A

    1986-12-01

    Ablation of the bovine crystalline lens was studied using radiation from an excimer laser at four ultraviolet wave lengths as follows: 193 nm (argon fluoride), 248 nm (krypton fluoride), 308 nm (xenon chloride), and 351 nm (xenon fluoride). The ablation process was quantitated by measuring mass ablated with an electronic balance, and characterized by examining ablation craters with scanning electron microscopy. The highest ablation rate was observed at 248 nm with lower rates at 193 and 308 nm. No ablation was observed at 351 nm. Scanning electron microscopy revealed the smoothest craters at 193 nm while at 248 nm there was vacuolization in the crater walls and greater disruption of surrounding tissue. The craters made at 308 nm did not have as smooth a contour as the 193-nm lesions. The spectral absorbance of the bovine lens was calculated at the wavelengths used for ablation and correlated with ablation rates and thresholds. High peak-power, pulsed ultraviolet laser radiation may have a role in surgical removal of the lens. PMID:3789982

  19. Local Ablation for Hepatocellular Carcinoma in Taiwan

    PubMed Central

    Lin, Shi-Ming

    2013-01-01

    Hepatocellular carcinoma (HCC) is the second commonest cancer in Taiwan. The national surveillance program can detect HCC in its early stages, and various curative modalities (including surgical resection, orthotopic liver transplantation, and local ablation) are employed for the treatment of small HCC. Local ablation therapies are currently advocated for early-stage HCC that is unresectable because of co-morbidities, the need to preserve liver function, or refusal of resection. Among the various local ablation therapies, the most commonly used modalities include percutaneous ethanol injection and radiofrequency ablation (RFA); percutaneous acetic acid injection and microwave ablation are used less often. RFA is more commonly employed than other local ablative modalities in Taiwan because the technique is highly effective, minimally invasive, and requires fewer sessions. RFA is therefore advocated in Taiwan as the first-line curative therapy for unresectable HCC or even for resectable HCC. However, current RFA procedures are less effective against tumors that are in high-risk or difficult-to-ablate locations, are poorly visualized on ultrasonography (US), or are large. Recent advancements in RFA in Taiwan can resolve these issues by the creation of artificial ascites or pleural effusion, application of real-time virtual US assistance, use of combination therapy before RFA, or use of switching RF controllers with multiple electrodes. This review article provides updates on the clinical outcomes and advances in local ablative modalities (mostly RFA) for HCC in Taiwan. PMID:24159599

  20. Radiofrequency catheter ablation of the atrioventricular junction from the left ventricle

    SciTech Connect

    Sousa, J.; el-Atassi, R.; Rosenheck, S.; Calkins, H.; Langberg, J.; Morady, F. )

    1991-08-01

    The purpose of this study was to describe a new technique for catheter ablation of the atrioventricular junction using radiofrequency energy delivered in the left ventricle. Catheter ablation of the atrioventricular (AV) junction using a catheter positioned across the tricuspid annulus was unsuccessful in eight patients with a mean {plus minus} SD age of 51 {plus minus} 19 years who had AV nodal reentry tachycardia (three patients), orthodromic tachycardia using a concealed midseptal accessory pathway, atrial tachycardia, atrial flutter (two patients), or atrial fibrillation. Before attempts at catheter ablation of the AV junction, each patient had been refractory to pharmacological therapy, and four had failed attempts at either catheter modification of the AV node using radiofrequency energy or surgical and catheter ablation of the accessory pathway. Conventional right-sided catheter ablation of the AV junction using radiofrequency energy in six patients and both radiofrequency energy and direct current shocks in two patients was ineffective. The mean amplitude of the His bundle potential recorded at the tricuspid annulus at the sites of unsuccessful AV junction ablation was 0.1 {plus minus} 0.08 mV, with a maximum His amplitude of 0.03-0.28 mV. A 7F deflectable-tip quadripolar electrode catheter with a 4-mm distal electrode was positioned against the upper left ventricular septum using a retrograde aortic approach from the femoral artery. Third-degree AV block was induced in each of the eight patients with 20-36 W applied for 15-30 seconds. The His bundle potential at the sites of successful AV junction ablation ranged from 0.06 to 0.99 mV, with a mean of 0.27 {plus minus} 0.32 mV. There was no rise in the creatine kinase-MB fraction and no complications occurred. An intrinsic escape rhythm of 30-60 beats/min was present in seven of the eight patients.

  1. Lung Cancer Ablation: Technologies and Techniques

    PubMed Central

    Alexander, Erica S.; Dupuy, Damian E.

    2013-01-01

    The incidence of lung cancers in 2012 is estimated to reach 226,160 new cases, with only a third of patients suitable surgical candidates. Tumor ablation has emerged as an important and efficacious treatment option for nonsurgical lung cancer patients. This localized minimally invasive therapy is best suited for small oligonodular lesions or favorably located metastatic tumors. Radiofrequency ablation has been in use for over a decade, and newer modalities including microwave ablation, cryoablation, and irreversible electroporation have emerged as additional treatment options for patients. Ablation therapies can offer patients and clinicians a repeatable and effective therapy for palliation and, in some cases, cure of thoracic malignancies. This article discusses the available technologies and techniques available for tumor ablation of thoracic malignancies including patient selection, basic aspects of procedure technique, imaging follow-up, treatment outcomes, and comparisons between various therapies. PMID:24436530

  2. Epicardial Ventricular Tachycardia Ablation for Which Patients?

    PubMed Central

    Roten, Laurent; Sacher, Frédéric; Daly, Matthew; Pascale, Patrizio; Komatsu, Yuki; Ramoul, Khaled; Scherr, Daniel; Chaumeil, Arnaud; Shah, Ashok; Denis, Arnaud; Derval, Nicolas; Hocini, Mélèze; Haïssaguerre, Michel; Jaïs, Pierre

    2012-01-01

    With the widespread use of implantable cardioverter-defibrillators, an increasing number of patients present with ventricular tachycardia (VT). Large multicentre studies have shown that ablation of VT successfully reduces recurrent VT and this procedure is being performed by an increasing number of centres. However, for a number of reasons, many patients experience VT recurrence after ablation. One important reason for VT recurrence is the presence of an epicardial substrate involved in the VT circuit which is not affected by endocardial ablation. Epicardial access and ablation is now frequently performed either after failed endocardial VT ablation or as first-line treatment in selected patients. This review will focus on the available evidence for identifying VT of epicardial origin, and discuss in which patients an epicardial approach would be benefitial. PMID:26835028

  3. Pulsed Laser Ablation of Soft Biological Tissues

    NASA Astrophysics Data System (ADS)

    Vogel, Alfred; Venugopalan, Vasan

    In this chapter we focus on the key elements that form our current understanding of the mechanisms of pulsed laser ablation of soft biological tissues. We present a conceptual framework providing mechanistic links between various ablation applications and the underlying thermodynamic and phase change processes [1]. We define pulsed laser ablation as the use of laser pulses with duration of ~1 ms or less for the incision or removal of tissue regardless of the photophysical or photochemical processes involved. However, we will confine this presentation to pulsed ablation performed on a tissue level that does not involve laser-induced plasma formation. Ablation processes within transparent tissues or cells resulting from non-linear absorption have been considered in reviews by Vogel and Venugopalan [1] and by Vogel and co-workers [2].

  4. RF Field Visualization of RF Ablation at the Larmor Frequency

    PubMed Central

    Stang, Pascal; Kerr, Adam; Pauly, John; Scott, Greig

    2012-01-01

    Radiofrequency ablation is an effective minimally invasive treatment for tumors. One primary source of difficulty is monitoring and controlling the ablation region. Currently, RF ablation is performed at 460 kHz, for which MRI could play a role given its capability for temperature monitoring and tumor visualization. If instead the ablation were to be performed at the MRI Larmor frequency, then the MR capability for B1 field mapping could be used to directly visualize the RF fields created by the ablation currents. Visualizing the RF fields may enable better control of the ablation currents, enabling better control of lesion shape and size and improving repeatability. We demonstrate the feasibility of performing RF ablations at 64 MHz and show preliminary results from imaging the RF fields from the ablation. The post-ablation RF fields show an increase in current density in the ablated region, consistent with an increase in conductivity of the ablated tissue. PMID:21775256

  5. Radiofrequency ablation for hepatocellular carcinoma.

    PubMed

    Nishikawa, Hiroki; Kimura, Toru; Kita, Ryuichi; Osaki, Yukio

    2013-09-01

    Hepatocellular carcinoma (HCC) is one of the most common causes of cancer-related mortality worldwide. Unfortunately, only 20% of HCC patients are amenable to curative therapy (liver transplantation or surgical resection). Locoregional therapies such as radiofrequency ablation (RFA), percutaneous ethanol injection, microwave coagulation therapy, and transcatheter arterial chemoembolisation play a key role in the management of HCC. The choice of the treatment modality depends on the size of the tumour, tumour location, anatomic considerations and the number of tumours present and liver function. RFA therapy for HCC can be performed safely using a percutaneous, laparoscopic, or an open approach, even in patients with poor functional reserve. Since the introduction of RFA, several randomised controlled trials and non-randomised studies comparing RFA and other therapies for HCC have been conducted. In addition, in the last decade there have been technical advances in RFA therapy for HCC, resulting in significant improvement in the prognosis of HCC patients treated with this modality. In this review, we primarily focus on percutaneous RFA therapy for HCC and refer to current knowledge and future perspectives for this therapy. We also discuss new emerging ablation techniques. PMID:23937321

  6. Stellar Ablation of Planetary Atmospheres

    NASA Technical Reports Server (NTRS)

    Moore, Thomas E.; Horwitz, J. L.

    2007-01-01

    We review observations and theories of the solar ablation of planetary atmospheres, focusing on the terrestrial case where a large magnetosphere holds off the solar wind, so that there is little direct atmospheric impact, but also couples the solar wind electromagnetically to the auroral zones. We consider the photothermal escape flows known as the polar wind or refilling flows, the enhanced mass flux escape flows that result from localized solar wind energy dissipation in the auroral zones, and the resultant enhanced neutral atom escape flows. We term these latter two escape flows the "auroral wind." We review observations and theories of the heating and acceleration of auroral winds, including energy inputs from precipitating particles, electromagnetic energy flux at magnetohydrodynamic and plasma wave frequencies, and acceleration by parallel electric fields and by convection pickup processes also known as "centrifugal acceleration." We consider also the global circulation of ionospheric plasmas within the magnetosphere, their participation in magnetospheric disturbances as absorbers of momentum and energy, and their ultimate loss from the magnetosphere into the downstream solar wind, loading reconnection processes that occur at high altitudes near the magnetospheric boundaries. We consider the role of planetary magnetization and the accumulating evidence of stellar ablation of extrasolar planetary atmospheres. Finally, we suggest and discuss future needs for both the theory and observation of the planetary ionospheres and their role in solar wind interactions, to achieve the generality required for a predictive science of the coupling of stellar and planetary atmospheres over the full range of possible conditions.

  7. Ablative shielding for hypervelocity projectiles

    NASA Technical Reports Server (NTRS)

    Rucker, Michelle A. (Inventor)

    1993-01-01

    A hypervelocity projectile shield which includes a hollow semi-flexible housing fabricated from a plastic like, or otherwise transparent membrane which is filled with a fluid (gas or liquid) is presented. The housing has a inlet valve, similar to that on a tire or basketball, to introduce an ablating fluid into the housing. The housing is attached by a Velcro mount or double-sided adhesive tape to the outside surface of a structure to be protected. The housings are arrayed in a side-by-side relationship for complete coverage of the surface to be protected. In use, when a hypervelocity projectile penetrates the outer wall of a housing it is broken up and then the projectile is ablated as it travels through the fluid, much like a meteorite 'burns up' as it enters the earth's atmosphere, and the housing is deflated. The deflated housing can be easily spotted for replacement, even from a distance. Replacement is then accomplished by simply pulling a deflated housing off the structure and installing a new housing.

  8. Initialized Fractional Calculus

    NASA Technical Reports Server (NTRS)

    Lorenzo, Carl F.; Hartley, Tom T.

    2000-01-01

    This paper demonstrates the need for a nonconstant initialization for the fractional calculus and establishes a basic definition set for the initialized fractional differintegral. This definition set allows the formalization of an initialized fractional calculus. Two basis calculi are considered; the Riemann-Liouville and the Grunwald fractional calculi. Two forms of initialization, terminal and side are developed.

  9. Tempered fractional calculus

    NASA Astrophysics Data System (ADS)

    Sabzikar, Farzad; Meerschaert, Mark M.; Chen, Jinghua

    2015-07-01

    Fractional derivatives and integrals are convolutions with a power law. Multiplying by an exponential factor leads to tempered fractional derivatives and integrals. Tempered fractional diffusion equations, where the usual second derivative in space is replaced by a tempered fractional derivative, govern the limits of random walk models with an exponentially tempered power law jump distribution. The limiting tempered stable probability densities exhibit semi-heavy tails, which are commonly observed in finance. Tempered power law waiting times lead to tempered fractional time derivatives, which have proven useful in geophysics. The tempered fractional derivative or integral of a Brownian motion, called a tempered fractional Brownian motion, can exhibit semi-long range dependence. The increments of this process, called tempered fractional Gaussian noise, provide a useful new stochastic model for wind speed data. A tempered fractional difference forms the basis for numerical methods to solve tempered fractional diffusion equations, and it also provides a useful new correlation model in time series.

  10. Tempered fractional calculus

    SciTech Connect

    Sabzikar, Farzad; Meerschaert, Mark M.; Chen, Jinghua

    2015-07-15

    Fractional derivatives and integrals are convolutions with a power law. Multiplying by an exponential factor leads to tempered fractional derivatives and integrals. Tempered fractional diffusion equations, where the usual second derivative in space is replaced by a tempered fractional derivative, govern the limits of random walk models with an exponentially tempered power law jump distribution. The limiting tempered stable probability densities exhibit semi-heavy tails, which are commonly observed in finance. Tempered power law waiting times lead to tempered fractional time derivatives, which have proven useful in geophysics. The tempered fractional derivative or integral of a Brownian motion, called a tempered fractional Brownian motion, can exhibit semi-long range dependence. The increments of this process, called tempered fractional Gaussian noise, provide a useful new stochastic model for wind speed data. A tempered fractional difference forms the basis for numerical methods to solve tempered fractional diffusion equations, and it also provides a useful new correlation model in time series.

  11. Which imaging modality is most effective for identifying pseudotumours in metal-on-metal hip resurfacings requiring revision

    PubMed Central

    Matharu, G. S.; Mansour, R.; Dada, O.; Ostlere, S.; Pandit, H. G.; Murray, D. W.

    2016-01-01

    Aims The aims of this study were to compare the diagnostic test characteristics of ultrasound alone, metal artefact reduction sequence MRI (MARS-MRI) alone, and ultrasound combined with MARS-MRI for identifying intra-operative pseudotumours in metal-on-metal hip resurfacing (MoMHR) patients undergoing revision surgery. Methods This retrospective diagnostic accuracy study involved 39 patients (40 MoMHRs). The time between imaging modalities was a mean of 14.6 days (0 to 90), with imaging performed at a mean of 5.3 months (0.06 to 12) before revision. The prevalence of intra-operative pseudotumours was 82.5% (n = 33). Results Agreement with the intra-operative findings was 82.5% (n = 33) for ultrasound alone, 87.5% (n = 35) for MARS-MRI alone, and 92.5% (n = 37) for ultrasound and MARS-MRI combined. The diagnostic characteristics for ultrasound alone and MARS-MRI alone reached similar sensitivities (90.9% vs 93.9%) and positive predictive values (PPVs; 88.2% vs 91.2%), but higher specificities (57.1% vs 42.9%) and negative predictive values (NPVs; 66.7% vs 50.0%) were achieved with MARS-MRI. Ultrasound and MARS-MRI combined produced 100% sensitivity and 100% NPV, whilst maintaining both specificity (57.1%) and PPV (91.7%). For the identification of a pseudotumour, which was confirmed at revision surgery, agreement was substantial for ultrasound and MARS-MRI combined (κ = 0.69), moderate for MARS-MRI alone (κ = 0.54), and fair for ultrasound alone (κ = 0.36). Discussion These findings suggest that ultrasound and/or MARS-MRI have a role when assessing patients with a MoMHR, with the choice dependent on local financial constraints and the availability of ultrasound expertise. However in patients with a MoMHR who require revision, combined imaging was most effective. Take home message: Combined imaging with ultrasound and MARS-MRI always identified intra-operative pseudotumours if present. Furthermore, if neither imaging modality showed a pseudotumour, one was not

  12. Effects of overlap and pass number in CO2 laser skin resurfacing: preliminary results of residual thermal damage, cell death, and wound healing

    NASA Astrophysics Data System (ADS)

    Ross, E. V.; Glatter, Robert D.; Duke, Daniella; Grevelink, Joop M.

    1997-05-01

    Newer carbon-dioxide laser systems incorporating short pulse and scanning technology have been used effectively to resurface the skin. Although scarring is rare, as the number of resurfacing cases has increased, some hypertrophic scarring has been observed. Previous dermabrasion and continuous wave (cw) carbon-dioxide studies suggest that depth of injury and/or thermal damage are important predictors of scarring for a given anatomic region. To determine if overlapping laser pulses/scans significantly altered wound healing, we examined residual thermal damage, cell death, and histologic and clinical wound healing in a farm pig. The Ultrapulse and SilkTouch systems were used with various radiant exposures, degrees of overlap, and numbers of passes. Thermal damage was assessed by histology, and dermal cell viability was measured with nitrotetrazolium blue staining. Presence or absence of clinical scarring was determined by noting textural change and loss of skin markings. We observed that thermal damage and cell death depth did not increase significantly with pass number; however, by double-pulsing or double-scanning sites, residual thermal damage and cell death depth were increased as much as 100% over areas without immediate overlap of laser impacts. Also, scarring was increased focally in areas with overlap. We conclude that immediate overlapping of carbon- dioxide laser pulses/scans is a significant risk factor in increasing thermal damage, cell death, and scarring.

  13. Cartilage resurfacing potential of PLGA scaffolds loaded with autologous cells from cartilage, fat, and bone marrow in an ovine model of osteochondral focal defect.

    PubMed

    Caminal, M; Peris, D; Fonseca, C; Barrachina, J; Codina, D; Rabanal, R M; Moll, X; Morist, A; García, F; Cairó, J J; Gòdia, F; Pla, A; Vives, J

    2016-08-01

    Current developments in tissue engineering strategies for articular cartilage regeneration focus on the design of supportive three-dimensional scaffolds and their use in combination with cells from different sources. The challenge of translating initial successes in small laboratory animals into the clinics involves pilot studies in large animal models, where safety and efficacy should be investigated during prolonged follow-up periods. Here we present, in a single study, the long-term (up to 1 year) effect of biocompatible porous scaffolds non-seeded and seeded with fresh ex vivo expanded autologous progenitor cells that were derived from three different cell sources [cartilage, fat and bone marrow (BM)] in order to evaluate their advantages as cartilage resurfacing agents. An ovine model of critical size osteochondral focal defect was used and the test items were implanted arthroscopically into the knees. Evidence of regeneration of hyaline quality tissue was observed at 6 and 12 months post-treatment with variable success depending on the cell source. Cartilage and BM-derived mesenchymal stromal cells (MSC), but not those derived from fat, resulted in the best quality of new cartilage, as judged qualitatively by magnetic resonance imaging and macroscopic assessment, and by histological quantitative scores. Given the limitations in sourcing cartilage tissue and the risk of donor site morbidity, BM emerges as a preferential source of MSC for novel cartilage resurfacing therapies of osteochondral defects using copolymeric poly-D,L-lactide-co-glycolide scaffolds. PMID:25595211

  14. Humeral Head Arthroplasty and Meniscal Allograft Resurfacing of the Glenoid: A Concise Follow-up of a Previous Report and Survivorship Analysis.

    PubMed

    Bois, Aaron J; Whitney, Ian J; Somerson, Jeremy S; Wirth, Michael A

    2015-10-01

    The two to five-year results of humeral head arthroplasty and lateral meniscal allograft resurfacing of the glenoid in patients fifty-five years of age or younger were previously reported by the senior author (M.A.W.). The purpose of the present study was to report the survival rate, clinical findings, and radiographic results of the original thirty shoulders (thirty patients) followed for a mean duration of 8.3 years (range, five to twelve years). The scores on the visual analog scale for pain, American Shoulder and Elbow Surgeons scoring system, and Simple Shoulder Test were significantly improved at the latest follow-up evaluation compared with the preoperative findings (p < 0.001). Radiographic indices of posterior subluxation did not significantly increase from the immediate postoperative imaging to the latest radiographs, while the glenohumeral joint space demonstrated a gradual decrease. Nine (30%) of thirty shoulders were known to have undergone a reoperation. The present study demonstrated that biological glenoid resurfacing combined with hemiarthroplasty can provide significant improvement in shoulder function and pain relief in young patients with glenohumeral arthritis; however, mid-term follow-up at a mean of over eight years demonstrated a high reoperation rate. PMID:26446964

  15. Iron isotope composition of particles produced by UV-femtosecond laser ablation of natural oxides, sulfides, and carbonates.

    PubMed

    d'Abzac, Francois-Xavier; Beard, Brian L; Czaja, Andrew D; Konishi, Hiromi; Schauer, James J; Johnson, Clark M

    2013-12-17

    The need for femtosecond laser ablation (fs-LA) systems coupled to MC-ICP-MS to accurately perform in situ stable isotope analyses remains an open question, because of the lack of knowledge concerning ablation-related isotopic fractionation in this regime. We report the first iron isotope analysis of size-resolved, laser-induced particles of natural magnetite, siderite, pyrrhotite, and pyrite, collected through cascade impaction, followed by analysis by solution nebulization MC-ICP-MS, as well as imaging using electron microscopy. Iron mass distributions are independent of mineralogy, and particle morphology includes both spheres and agglomerates for all ablated phases. X-ray spectroscopy shows elemental fractionation in siderite (C-rich agglomerates) and pyrrhotite/pyrite (S-rich spheres). We find an increase in (56)Fe/(54)Fe ratios of +2‰, +1.2‰, and +0.8‰ with increasing particle size for magnetite, siderite, and pyrrhotite, respectively. Fe isotope differences in size-sorted aerosols from pyrite ablation are not analytically resolvable. Experimental data are discussed using models of particles generation by Hergenröder and elemental/isotopic fractionation by Richter. We interpret the isotopic fractionation to be related to the iron condensation time scale, dependent on its saturation in the gas phase, as a function of mineral composition. Despite the isotopic variations across aerosol size fractions, total aerosol composition, as calculated from mass balance, confirms that fs-LA produces a stoichiometric sampling in terms of isotopic composition. Specifically, both elemental and isotopic fractionation are produced by particle generation processes and not by femtosecond laser-matter interactions. These results provide critical insights into the analytical requirements for laser-ablation-based stable isotope measurements of high-precision and accuracy in geological samples, including the importance of quantitative aerosol transport to the ICP. PMID

  16. TEMPERED FRACTIONAL CALCULUS

    PubMed Central

    MEERSCHAERT, MARK M.; SABZIKAR, FARZAD; CHEN, JINGHUA

    2014-01-01

    Fractional derivatives and integrals are convolutions with a power law. Multiplying by an exponential factor leads to tempered fractional derivatives and integrals. Tempered fractional diffusion equations, where the usual second derivative in space is replaced by a tempered fractional derivative, govern the limits of random walk models with an exponentially tempered power law jump distribution. The limiting tempered stable probability densities exhibit semi-heavy tails, which are commonly observed in finance. Tempered power law waiting times lead to tempered fractional time derivatives, which have proven useful in geophysics. The tempered fractional derivative or integral of a Brownian motion, called a tempered fractional Brownian motion, can exhibit semi-long range dependence. The increments of this process, called tempered fractional Gaussian noise, provide a useful new stochastic model for wind speed data. A tempered difference forms the basis for numerical methods to solve tempered fractional diffusion equations, and it also provides a useful new correlation model in time series. PMID:26085690

  17. Subpicosecond laser ablation of dental enamel

    NASA Astrophysics Data System (ADS)

    Rode, A. V.; Gamaly, E. G.; Luther-Davies, B.; Taylor, B. T.; Dawes, J.; Chan, A.; Lowe, R. M.; Hannaford, P.

    2002-08-01

    Laser ablation of dental enamel with subpicosecond laser pulses has been studied over the intensity range of (0.1-1.4) x1014 W/cm2 using 95 and 150 fs pulses at a pulse repetition rate of 1 kHz. The experimentally determined ablation threshold of 2.2plus-or-minus0.1 J/cm2 was in good agreement with theoretical predictions based on an electrostatic ablation model. The ablation rate increased linearly with the laser fluence for up to 15 times the ablation threshold. The absence of collateral damage was observed using optical and scanning electron microscopy. Pulpal temperature measurements showed an increase of about 10 degC during the 200 s course of ablation. However, air cooling at a rate of 5 l/min resulted in the intrapulpal temperature being maintained below the pulpal damage threshhold of 5.5 degC. The material removal rates for subpicosecond precision laser ablation of dental enamel are compared with other techniques.

  18. Neural Ablation and Regeneration in Pain Practice.

    PubMed

    Choi, Eun Ji; Choi, Yun Mi; Jang, Eun Jung; Kim, Ju Yeon; Kim, Tae Kyun; Kim, Kyung Hoon

    2016-01-01

    A nerve block is an effective tool for diagnostic and therapeutic methods. If a diagnostic nerve block is successful for pain relief and the subsequent therapeutic nerve block is effective for only a limited duration, the next step that should be considered is a nerve ablation or modulation. The nerve ablation causes iatrogenic neural degeneration aiming only for sensory or sympathetic denervation without motor deficits. Nerve ablation produces the interruption of axonal continuity, degeneration of nerve fibers distal to the lesion (Wallerian degeneration), and the eventual death of axotomized neurons. The nerve ablation methods currently available for resection/removal of innervation are performed by either chemical or thermal ablation. Meanwhile, the nerve modulation method for interruption of innervation is performed using an electromagnetic field of pulsed radiofrequency. According to Sunderland's classification, it is first and foremost suggested that current neural ablations produce third degree peripheral nerve injury (PNI) to the myelin, axon, and endoneurium without any disruption of the fascicular arrangement, perineurium, and epineurium. The merit of Sunderland's third degree PNI is to produce a reversible injury. However, its shortcoming is the recurrence of pain and the necessity of repeated ablative procedures. The molecular mechanisms related to axonal regeneration after injury include cross-talk between axons and glial cells, neurotrophic factors, extracellular matrix molecules, and their receptors. It is essential to establish a safe, long-standing denervation method without any complications in future practices based on the mechanisms of nerve degeneration as well as following regeneration. PMID:26839664

  19. On the Ablation Models of Fuel Pellets

    SciTech Connect

    Rozhansky, V.A.; Senichenkov, I.Yu.

    2005-12-15

    The neutral gas shielding model and neutral-gas-plasma shielding model are analyzed qualitatively. The main physical processes that govern the formation of the shielding gas cloud and, consequently, the ablation rate are considered. For the neutral gas shielding model, simple formulas relating the ablation rate and cloud parameters to the parameters of the pellet and the background plasma are presented. The estimates of the efficiency of neutral gas shielding and plasma shielding are compared. It is shown that the main portion of the energy flux of the background electrons is released in the plasma cloud. Formulas for the ablation rate and plasma parameters are derived in the neutral-gas-plasma shielding model. The question is discussed as to why the neutral gas shielding model describes well the ablation rate of the pellet material, although it does not take into account the ionization effects and the effects associated with the interaction of ionized particles with the magnetic field. The reason is that the ablation rate depends weakly on the energy flux of hot electrons; as a result, the attenuation of this flux by the electrostatic shielding and plasma shielding has little effect on the ablation rate. This justifies the use of the neutral gas shielding model to estimate the ablation rate (to within a factor of about 2) over a wide range of parameters of the pellet and the background plasma.

  20. Neural Ablation and Regeneration in Pain Practice

    PubMed Central

    Choi, Eun Ji; Choi, Yun Mi; Jang, Eun Jung; Kim, Ju Yeon; Kim, Tae Kyun

    2016-01-01

    A nerve block is an effective tool for diagnostic and therapeutic methods. If a diagnostic nerve block is successful for pain relief and the subsequent therapeutic nerve block is effective for only a limited duration, the next step that should be considered is a nerve ablation or modulation. The nerve ablation causes iatrogenic neural degeneration aiming only for sensory or sympathetic denervation without motor deficits. Nerve ablation produces the interruption of axonal continuity, degeneration of nerve fibers distal to the lesion (Wallerian degeneration), and the eventual death of axotomized neurons. The nerve ablation methods currently available for resection/removal of innervation are performed by either chemical or thermal ablation. Meanwhile, the nerve modulation method for interruption of innervation is performed using an electromagnetic field of pulsed radiofrequency. According to Sunderland's classification, it is first and foremost suggested that current neural ablations produce third degree peripheral nerve injury (PNI) to the myelin, axon, and endoneurium without any disruption of the fascicular arrangement, perineurium, and epineurium. The merit of Sunderland's third degree PNI is to produce a reversible injury. However, its shortcoming is the recurrence of pain and the necessity of repeated ablative procedures. The molecular mechanisms related to axonal regeneration after injury include cross-talk between axons and glial cells, neurotrophic factors, extracellular matrix molecules, and their receptors. It is essential to establish a safe, long-standing denervation method without any complications in future practices based on the mechanisms of nerve degeneration as well as following regeneration. PMID:26839664

  1. A preliminary study on the safety and efficacy of a novel fractional CO₂ laser with synchronous radiofrequency delivery.

    PubMed

    Gotkin, Robert H; Sarnoff, Deborah S

    2014-03-01

    Building upon the fractional CO₂ technology incorporated into the first generation SmartXide DOT (DEKA / ElEn, SpA, Calenzano, Italy) introduced in the U.S. in 2008, a second generation SmartXide Quadro has recently been introduced. This is a versatile device that has the ability to combine fractional CO₂ laser output for skin resurfacing with the synchronous delivery of bipolar radiofrequency (RF) energy for deeper, more diffuse heating. A pilot study was undertaken to demonstrate the safety and efficacy of the SmartXide Quadro, employing both fractional CO₂ laser output combined with the synchronous delivery of radiofrequency energy for the treatment of facial rhytides and acne scars. Ten patients, all women, six with facial rhytides and four with acne scarring, were treated with the SmartXide Quadro, a variably pulsed CO₂ laser with Pulse Shape Design® technology, a microablative DOT scanner and synchronized bipolar RF emission. Each patient was treated with a single fractional CO₂ laser-RF treatment; laser and RF parameters varied according to the severity of the rhytides or acne scars and were based upon both manufacturer-recommended settings and surgeon experience. Follow-up was at three days, one week, 2 weeks, and one month, three months, and six months after treatment. Results were judged by comparison of preoperative and post-operative photos evaluated by independent physicians, preoperative and post-operative grading by treating physicians, subjective evaluation of results by the patients themselves, and tabulation and categorization of adverse events (AEs). The SmartXide Quadro variably pulsed CO₂ laser with a microablative DOT scanner, with synchronous delivery of bipolar RF energy emission, proved to be both safe and effective in the treatment of facial rhytides and acne scars. The single treatment protocol was well tolerated and recovery was similar to fractional CO₂ laser skin resurfacing alone. The AEs were minimal and no significant

  2. Thermal protection system ablation sensor

    NASA Technical Reports Server (NTRS)

    Gorbunov, Sergey (Inventor); Martinez, Edward R. (Inventor); Scott, James B. (Inventor); Oishi, Tomomi (Inventor); Fu, Johnny (Inventor); Mach, Joseph G. (Inventor); Santos, Jose B. (Inventor)

    2011-01-01

    An isotherm sensor tracks space vehicle temperatures by a thermal protection system (TPS) material during vehicle re-entry as a function of time, and surface recession through calibration, calculation, analysis and exposed surface modeling. Sensor design includes: two resistive conductors, wound around a tube, with a first end of each conductor connected to a constant current source, and second ends electrically insulated from each other by a selected material that becomes an electrically conductive char at higher temperatures to thereby complete an electrical circuit. The sensor conductors become shorter as ablation proceeds and reduced resistance in the completed electrical circuit (proportional to conductor length) is continually monitored, using measured end-to-end voltage change or current in the circuit. Thermocouple and/or piezoelectric measurements provide consistency checks on local temperatures.

  3. FRACTIONAL INTEGRATION TOOLBOX

    PubMed Central

    Marinov, Toma M.; Ramirez, Nelson; Santamaria, Fidel

    2014-01-01

    The problems formulated in the fractional calculus framework often require numerical fractional integration/differentiation of large data sets. Several existing fractional control toolboxes are capable of performing fractional calculus operations, however, none of them can efficiently perform numerical integration on multiple large data sequences. We developed a Fractional Integration Toolbox (FIT), which efficiently performs fractional numerical integration/differentiation of the Riemann-Liouville type on large data sequences. The toolbox allows parallelization and is designed to be deployed on both CPU and GPU platforms. PMID:24812536

  4. Repigmentation of Hypopigmented Scars Using Combination of Fractionated Carbon Dioxide Laser with Topical Latanoprost Vs. Fractionated Carbon Dioxide Laser Alone

    PubMed Central

    Siadat, Amir Hossein; Rezaei, Reza; Asilian, Ali; Abtahi-Naeini, Bahareh; Rakhshanpour, Mehrdad; Raei, Mehdi; Hosseini, Seyed Mohsen

    2015-01-01

    Background: Fractionated carbon dioxide (CO2) can treat hypopigmented scars. Latanoprost is a prostaglandin analog used to treat glaucoma. It can cause adverse effects, such as periocular hyperpigmentation. The aim of this study was to assess the efficacy and safety of latanoprost plus CO2 laser on the repigmentation of hypopigmented scars. Patients and Methods: 28 patients with hypopigmented scars were divided randomly into two groups. The patients in group A were treated in six sessions (1-month intervals) with 10600-nm fractional CO2 laser plus latanoprost 0.005% and those of group B fractionated CO2 laser plus placebo (distilled water). Digital photographs were taken at baseline and 3 months after the last treatment session. The blinded dermatologist compared the photographs and evaluated the efficacy of treatment in the hypopigmented scars using a 4-scale point (grade 1-4). Patient satisfaction was scored from 0 to 10 on a visual analog scale. Results: Follow-up results 12 weeks after the last treatment session demonstrated that 11 of the 14 patients in group A had more than 50% improvement in hypopigmentation The difference in improvement of the two groups was statistically significant (P = 0.027). The mean of the VAS scores of patients in group A was 6.50 ± 1.45 and in group B 4.57 ± 1.6. The difference in mean satisfaction of the two groups was statistically significant (P = 0.003). Side effects were mild and resolved within 1 to 5 days. Conclusion: The fractional CO2 laser resurfacing plus topical latanoprost can be used as a safe and efficacious method to treat hypopigmented scars. PMID:26288404

  5. High geocentric velocity meteor ablation

    NASA Astrophysics Data System (ADS)

    Hill, K. A.; Rogers, L. A.; Hawkes, R. L.

    2005-12-01

    Interstellar origin meteoroids have now been detected using radar, image intensified video, large aperture radar and space dust impact techniques. Dynamical and radiation production mechanisms will eject some meteoroids from other planetary systems into orbits which will impact Earth with high geocentric velocities. In this paper we numerically model the ablation of high geocentric velocity (71 to 500~km s-1) meteors in order to predict the heights, light curves and trail lengths to be expected. We modeled three compositions and structures: asteroidal, cometary and porous cometary. Meteoroid masses ranging from 10-6 to 10-13~kg were used in the model. As expected, these high geocentric velocity meteors, when compared to other meteors, ablate higher in the atmosphere. For example a 300~km s-1 cometary structure meteor of mass 10-9~kg will have a peak luminosity at about 190 km. They will also have significantly longer trail lengths. The same 300~km s-1, 10-9~kg cometary meteor would be within 2 mag of its peak brightness for a vertical displacement of 60 km if incident at a zenith angle of 45°. The peak light intensity of these high geocentric velocity meteors changes only slowly with velocity. Although the incident kinetic energy per unit time increases dramatically, this is largely offset by a decrease in the optical luminous efficiency in this velocity regime according to our luminous efficiency model. The 300~km s-1, 10-9~kg cometary meteor would have an absolute meteor magnitude at peak luminosity of about +8.5 mag. Our results suggest that at least those high geocentric velocity meteors larger than about 10-8~kg should be observable with current meteor electro-optical technology although there may be observational biases against their detection. The results of this paper can be used to help optimize a search strategy for these very high geocentric velocity meteors.

  6. Atrioventricular Junction Ablation for Atrial Fibrillation.

    PubMed

    Patel, Dilesh; Daoud, Emile G

    2016-04-01

    Atrioventricular junction (AVJ) ablation is an effective therapy in patients with symptomatic atrial fibrillation who are intolerant to or unsuccessfully managed with rhythm control or medical rate control strategies. A drawback is that the procedure mandates a pacing system. Overall, the safety and efficacy of AVJ ablation is high with a majority of the patients reporting significant improvement in symptoms and quality-of-life measures. Risk of sudden cardiac death after device implantation is low, especially with an appropriate postprocedure pacing rate. Mortality benefit with AVJ ablation has been shown in patients with heart failure and cardiac resynchronization therapy devices. PMID:26968669

  7. Atrioventricular junction ablation for atrial fibrillation.

    PubMed

    Patel, Dilesh; Daoud, Emile G

    2014-11-01

    Atrioventricular junction (AVJ) ablation is an effective therapy in patients with symptomatic atrial fibrillation who are intolerant to or unsuccessfully managed with rhythm control or medical rate control strategies. A drawback is that the procedure mandates a pacing system. Overall, the safety and efficacy of AVJ ablation is high with a majority of the patients reporting significant improvement in symptoms and quality-of-life measures. Risk of sudden cardiac death after device implantation is low, especially with an appropriate postprocedure pacing rate. Mortality benefit with AVJ ablation has been shown in patients with heart failure and cardiac resynchronization therapy devices. PMID:25443238

  8. Diamond Ablators for Inertial Confinement Fusion

    SciTech Connect

    Biener, J; Mirkarimi, P B; Tringe, J W; Baker, S L; Wang, Y M; Kucheyev, S O; Teslich, N E; Wu, K J; Hamza, A V; Wild, C; Woerner, E; Koidl, P; Bruehne, K; Fecht, H

    2005-06-21

    Diamond has a unique combination of physical properties for the inertial confinement fusion ablator application, such as appropriate optical properties, high atomic density, high yield strength, and high thermal conductivity. Here, we present a feasible concept to fabricate diamond ablator shells. The fabrication of diamond capsules is a multi-step process, which involves diamond chemical vapor deposition on silicon mandrels followed by polishing, microfabrication of holes, and removing of the silicon mandrel by an etch process. We also discuss the pros and cons of coarse-grained optical quality and nanocrystalline chemical vapor deposition diamond films for the ablator application.

  9. Catheter ablation of inappropriate sinus tachycardia.

    PubMed

    Gianni, Carola; Di Biase, Luigi; Mohanty, Sanghamitra; Gökoğlan, Yalçın; Güneş, Mahmut F; Horton, Rodney; Hranitzky, Patrick M; Burkhardt, J David; Natale, Andrea

    2016-06-01

    Catheter ablation for inappropriate sinus tachycardia (IST) is recommended for patients symptomatic for palpitations and refractory to other treatments. The current approach consists in sinus node modification (SNM), achieved by ablation of the cranial part of the sinus node to eliminate faster sinus rates while trying to preserve chronotropic competence. This approach has a limited efficacy, with a very modest long-term clinical success. To overcome this, proper patient selection is crucial and an epicardial approach should always be considered. This brief review will discuss the current role and limitations of catheter ablation in the management of patients with IST. PMID:26310299

  10. Investigation of different liquid media and ablation times on pulsed laser ablation synthesis of aluminum nanoparticles

    NASA Astrophysics Data System (ADS)

    Baladi, Arash; Sarraf Mamoory, Rasoul

    2010-10-01

    Aluminum nanoparticles were synthesized by pulsed laser ablation of Al targets in ethanol, acetone, and ethylene glycol. Transmission Electron Microscope (TEM) and Scanning Electron Microscope (SEM) images, Particle size distribution diagram from Laser Particle Size Analyzer (LPSA), UV-visible absorption spectra, and weight changes of targets were used for the characterization and comparison of products. The experiments demonstrated that ablation efficiency in ethylene glycol is too low, in ethanol is higher, and in acetone is highest. Comparison between ethanol and acetone clarified that acetone medium leads to finer nanoparticles (mean diameter of 30 nm) with narrower size distribution (from 10 to 100 nm). However, thin carbon layer coats some of them, which was not observed in ethanol medium. It was also revealed that higher ablation time resulted in higher ablated mass, but lower ablation rate. Finer nanoparticles, moreover, were synthesized in higher ablation times.

  11. Current Tumor Ablation Technologies: Basic Science and Device Review

    PubMed Central

    Saldanha, David F.; Khiatani, Vishal L.; Carrillo, Tami C.; Yap, Felix Y.; Bui, James T.; Knuttinen, M. Grace; Owens, Charles A.; Gaba, Ron C.

    2010-01-01

    Image-guided tumor ablation is an increasingly utilized tool to treat focal malignancy. Tumor ablation can be divided into two large categories, thermal and chemical ablation. The authors provide an overview of the current methods used to achieve thermal and chemical ablation of tumors, specifically addressing the basic science behind the ablation methods as well as providing a brief synopsis of the commercial devices currently available for use in the United States. PMID:22550363

  12. Dual beam optical system for pulsed laser ablation film deposition

    DOEpatents

    Mashburn, D.N.

    1996-09-24

    A laser ablation apparatus having a laser source outputting a laser ablation beam includes an ablation chamber having a sidewall, a beam divider for dividing the laser ablation beam into two substantially equal halves, and a pair of mirrors for converging the two halves on a surface of the target from complementary angles relative to the target surface normal, thereby generating a plume of ablated material emanating from the target. 3 figs.

  13. Femtosecond laser ablation of dentin and enamel: relationship between laser fluence and ablation efficiency

    NASA Astrophysics Data System (ADS)

    Chen, Hu; Liu, Jing; Li, Hong; Ge, Wenqi; Sun, Yuchun; Wang, Yong; Lü, Peijun

    2015-02-01

    The objective was to study the relationship between laser fluence and ablation efficiency of a femtosecond laser with a Gaussian-shaped pulse used to ablate dentin and enamel for prosthodontic tooth preparation. A diode-pumped thin-disk femtosecond laser with wavelength of 1025 nm and pulse width of 400 fs was used for the ablation of dentin and enamel. The laser spot was guided in a line on the dentin and enamel surfaces to form a groove-shaped ablation zone under a series of laser pulse energies. The width and volume of the ablated line were measured under a three-dimensional confocal microscope to calculate the ablation efficiency. Ablation efficiency for dentin reached a maximum value of 0.020 mm3/J when the laser fluence was set at 6.51 J/cm2. For enamel, the maximum ablation efficiency was 0.009 mm3/J at a fluence of 7.59 J/cm2. Ablation efficiency of the femtosecond laser on dentin and enamel is closely related to the laser fluence and may reach a maximum when the laser fluence is set to an appropriate value.

  14. The effect of ultrafast laser wavelength on ablation properties and implications on sample introduction in inductively coupled plasma mass spectrometry

    PubMed Central

    LaHaye, N. L.; Harilal, S. S.; Diwakar, P. K.; Hassanein, A.; Kulkarni, P.

    2015-01-01

    We investigated the role of femtosecond (fs) laser wavelength on laser ablation (LA) and its relation to laser generated aerosol counts and particle distribution, inductively coupled plasma-mass spectrometry (ICP-MS) signal intensity, detection limits, and elemental fractionation. Four different NIST standard reference materials (610, 613, 615, and 616) were ablated using 400 nm and 800 nm fs laser pulses to study the effect of wavelength on laser ablation rate, accuracy, precision, and fractionation. Our results show that the detection limits are lower for 400 nm laser excitation than 800 nm laser excitation at lower laser energies but approximately equal at higher energies. Ablation threshold was also found to be lower for 400 nm than 800 nm laser excitation. Particle size distributions are very similar for 400 nm and 800 nm wavelengths; however, they differ significantly in counts at similar laser fluence levels. This study concludes that 400 nm LA is more beneficial for sample introduction in ICP-MS, particularly when lower laser energies are to be used for ablation. PMID:26640294

  15. The effect of ultrafast laser wavelength on ablation properties and implications on sample introduction in inductively coupled plasma mass spectrometry

    SciTech Connect

    LaHaye, N. L.; Harilal, S. S.; Diwakar, P. K.; Hassanein, A.; Kulkarni, P.

    2013-07-14

    We investigated the role of femtosecond (fs) laser wavelength on laser ablation (LA) and its relation to laser generated aerosol counts and particle distribution, inductively coupled plasma-mass spectrometry (ICP-MS) signal intensity, detection limits, and elemental fractionation. Four different NIST standard reference materials (610, 613, 615, and 616) were ablated using 400 nm and 800 nm fs laser pulses to study the effect of wavelength on laser ablation rate, accuracy, precision, and fractionation. Our results show that the detection limits are lower for 400 nm laser excitation than 800 nm laser excitation at lower laser energies but approximately equal at higher energies. Ablation threshold was also found to be lower for 400 nm than 800 nm laser excitation. Particle size distributions are very similar for 400 nm and 800 nm wavelengths; however, they differ significantly in counts at similar laser fluence levels. This study concludes that 400 nm LA is more beneficial for sample introduction in ICP-MS, particularly when lower laser energies are to be used for ablation.

  16. DIY Fraction Pack.

    ERIC Educational Resources Information Center

    Graham, Alan; Graham, Louise

    2003-01-01

    Describes a very successful attempt to teach fractions to year 5 pupils based on pupils making their own fraction pack. Children decided for themselves how to make the fractional slices used in the activity using colored cardboard sheets and templates of a paper circle consisting of 24 equal slices. (Author/NB)

  17. Femtosecond laser ablation of the stapes

    PubMed Central

    McCaughey, Ryan G.; Sun, Hui; Rothholtz, Vanessa S.; Juhasz, Tibor; Wong, Brian J. F.

    2014-01-01

    A femtosecond laser, normally used for LASIK eye surgery, is used to perforate cadaveric human stapes. The thermal side effects of bone ablation are measured with a thermocouple in an inner ear model and are found to be within acceptable limits for inner ear surgery. Stress and acoustic events, recorded with piezoelectric film and a microphone, respectively, are found to be negligible. Optical microscopy, scanning electron microscopy, and optical coherence tomography are used to confirm the precision of the ablation craters and lack of damage to the surrounding tissue. Ablation is compared to that from an Er:YAG laser, the current laser of choice for stapedotomy, and is found to be superior. Ultra-short-pulsed lasers offer a precise and efficient ablation of the stapes, with minimal thermal and negligible mechanical and acoustic damage. They are, therefore, ideal for stapedotomy operations. PMID:19405768

  18. [Ablation of supraventricular tachycardias : Complications and emergencies].

    PubMed

    Sawan, N; Eitel, C; Thiele, H; Tilz, R

    2016-06-01

    Catheter ablation is an established treatment of supraventricular tachycardias (SVT) with high success rates of > 95 %. Complication rates range from 3 to 5 %, with serious complications occurring in about 0.8 %. There are general complications caused either by the vascular access or the catheters (e. g. hematomas, hemo-pneumothorax, embolism, thrombosis and aspiration) und specific ablation related complications (e. g. AV block during ablation of the slow pathway). The complication risk is elevated in elderly and multimorbid patients. Furthermore, the experience of the treating physician and the respective team plays an essential role. The purpose of this article is to give an overview on incidences, causes and management as well as prevention strategies of complications associated with catheter ablation of SVT. PMID:27206630

  19. Femtosecond laser ablation of the stapes

    NASA Astrophysics Data System (ADS)

    McCaughey, Ryan G.; Sun, Hui; Rothholtz, Vanessa S.; Juhasz, Tibor; Wong, Brian J. F.

    2009-03-01

    A femtosecond laser, normally used for LASIK eye surgery, is used to perforate cadaveric human stapes. The thermal side effects of bone ablation are measured with a thermocouple in an inner ear model and are found to be within acceptable limits for inner ear surgery. Stress and acoustic events, recorded with piezoelectric film and a microphone, respectively, are found to be negligible. Optical microscopy, scanning electron microscopy, and optical coherence tomography are used to confirm the precision of the ablation craters and lack of damage to the surrounding tissue. Ablation is compared to that from an Er:YAG laser, the current laser of choice for stapedotomy, and is found to be superior. Ultra-short-pulsed lasers offer a precise and efficient ablation of the stapes, with minimal thermal and negligible mechanical and acoustic damage. They are, therefore, ideal for stapedotomy operations.

  20. Optical Effects on Laser Ablated Polymer Surfaces

    NASA Astrophysics Data System (ADS)

    Prabhu, R. D.; Govinthasamy, R.; Murthy, N. S.

    2006-03-01

    Laser ablation of poly (ethylene terephthalate) and polyimide films were investigated using Excimer-UV laser. SEM analyses indicate the presence of rings for a wide range of ablation parameters (fluence, frequency and number of pulses). It is proposed that the particles present in the plasma plume could cause the incident laser light to diffract, similar to the optical effects observed in the femtosecond laser ablation of solids. The polymer surface provides a perfect medium to register the optical signatures as seen in the SEM images. The fringe-spacings observed in the images are compared with the theoretical diffraction patterns and the height of the plasma particles above the surface is estimated using an optimization scheme. The results of the analysis are consistent with experimentally observed dynamics of the plasma plume. It is proposed that such optical effects could be a routine feature in the laser ablation of polymers. The significance of such artifacts for lithography is discussed.

  1. Photodynamic therapy toward selective endometrial ablation

    NASA Astrophysics Data System (ADS)

    Tadir, Yona; Tromberg, Bruce J.; Krasieva, Tatiana B.; Berns, Michael W.

    1993-05-01

    Potential applications of photodynamic therapy for endometrial disease are discussed. Experimental models that may lead to diagnosis and treatment of endometriosis as well as selective endometrial ablation are summarized.

  2. Left Atrial Anatomy Relevant to Catheter Ablation

    PubMed Central

    Sánchez-Quintana, Damián; Cabrera, José Angel; Saremi, Farhood

    2014-01-01

    The rapid development of interventional procedures for the treatment of arrhythmias in humans, especially the use of catheter ablation techniques, has renewed interest in cardiac anatomy. Although the substrates of atrial fibrillation (AF), its initiation and maintenance, remain to be fully elucidated, catheter ablation in the left atrium (LA) has become a common therapeutic option for patients with this arrhythmia. Using ablation catheters, various isolation lines and focal targets are created, the majority of which are based on gross anatomical, electroanatomical, and myoarchitectual patterns of the left atrial wall. Our aim was therefore to review the gross morphological and architectural features of the LA and their relations to extracardiac structures. The latter have also become relevant because extracardiac complications of AF ablation can occur, due to injuries to the phrenic and vagal plexus nerves, adjacent coronary arteries, or the esophageal wall causing devastating consequences. PMID:25057427

  3. Laser ablation inductively coupled plasma mass spectrometry

    SciTech Connect

    Durrant, S.F.

    1996-07-01

    Laser ablation for solid sample introduction to inductively coupled plasma mass spectrometry for bulk and spatially-resolved elemental analysis is briefly reviewed. {copyright} {ital 1996 American Institute of Physics.}

  4. Thermal Ablation Modeling for Silicate Materials

    NASA Technical Reports Server (NTRS)

    Chen, Yih-Kanq

    2016-01-01

    A general thermal ablation model for silicates is proposed. The model includes the mass losses through the balance between evaporation and condensation, and through the moving molten layer driven by surface shear force and pressure gradient. This model can be applied in the ablation simulation of the meteoroid and the glassy ablator for spacecraft Thermal Protection Systems. Time-dependent axisymmetric computations are performed by coupling the fluid dynamics code, Data-Parallel Line Relaxation program, with the material response code, Two-dimensional Implicit Thermal Ablation simulation program, to predict the mass lost rates and shape change. The predicted mass loss rates will be compared with available data for model validation, and parametric studies will also be performed for meteoroid earth entry conditions.

  5. Nanoscale ablation through optically trapped microspheres

    NASA Astrophysics Data System (ADS)

    Fardel, Romain; McLeod, Euan; Tsai, Yu-Cheng; Arnold, Craig B.

    2010-10-01

    The ability to directly create patterns with size scales below 100 nm is important for many applications where the production or repair of high resolution and density features is needed. Laser-based direct-write methods have the benefit of being able to quickly and easily modify and create structures on existing devices, but ablation can negatively impact the overall technique. In this paper we show that self-positioning of near-field objectives through the optical trap assisted nanopatterning (OTAN) method allows for ablation without harming the objective elements. Small microbeads are positioned in close proximity to a substrate where ablation is initiated. Upon ablation, these beads are temporarily displaced from the trap but rapidly return to the initial position. We analyze the range of fluence values for which this process occurs and find that there exists a critical threshold beyond which the beads are permanently ejected.

  6. Stereotactic Ablative Radiotherapy for Oligometastatic Disease in Liver

    PubMed Central

    Kim, Myungsoo; Son, Seok Hyun; Won, Yong Kyun; Kay, Chul Seung

    2014-01-01

    Liver metastasis in solid tumors, including colorectal cancer, is the most frequent and lethal complication. The development of systemic therapy has led to prolonged survival. However, in selected patients with a finite number of discrete lesions in liver, defined as oligometastatic state, additional local therapies such as surgical resection, radiofrequency ablation, cryotherapy, and radiotherapy can lead to permanent local disease control and improve survival. Among these, an advance in radiation therapy made it possible to deliver high dose radiation to the tumor more accurately, without impairing the liver function. In recent years, the introduction of stereotactic ablative radiotherapy (SABR) has offered even more intensive tumor dose escalation in a few fractions with reduced dose to the adjacent normal liver. Many studies have shown that SABR for oligometastases is effective and safe, with local control rates widely ranging from 50% to 100% at one or two years. And actuarial survival at one and two years has been reported ranging from 72% to 94% and from 30% to 62%, respectively, without severe toxicities. In this paper, we described the definition and technical aspects of SABR, clinical outcomes including efficacy and toxicity, and related parameters after SABR in liver oligometastases from colorectal cancer. PMID:24868526

  7. Stereotactic ablative radiotherapy for oligometastatic disease in liver.

    PubMed

    Kim, Myungsoo; Son, Seok Hyun; Won, Yong Kyun; Kay, Chul Seung

    2014-01-01

    Liver metastasis in solid tumors, including colorectal cancer, is the most frequent and lethal complication. The development of systemic therapy has led to prolonged survival. However, in selected patients with a finite number of discrete lesions in liver, defined as oligometastatic state, additional local therapies such as surgical resection, radiofrequency ablation, cryotherapy, and radiotherapy can lead to permanent local disease control and improve survival. Among these, an advance in radiation therapy made it possible to deliver high dose radiation to the tumor more accurately, without impairing the liver function. In recent years, the introduction of stereotactic ablative radiotherapy (SABR) has offered even more intensive tumor dose escalation in a few fractions with reduced dose to the adjacent normal liver. Many studies have shown that SABR for oligometastases is effective and safe, with local control rates widely ranging from 50% to 100% at one or two years. And actuarial survival at one and two years has been reported ranging from 72% to 94% and from 30% to 62%, respectively, without severe toxicities. In this paper, we described the definition and technical aspects of SABR, clinical outcomes including efficacy and toxicity, and related parameters after SABR in liver oligometastases from colorectal cancer. PMID:24868526

  8. Photogrammetric recession measurements of an ablating surface

    NASA Technical Reports Server (NTRS)

    Schairer, Edward T. (Inventor); Heineck, James T. (Inventor)

    2012-01-01

    An instrument and method for measuring the time history of recession of an ablating surface of a test article during testing in a high enthalpy thermal test facility, such as an arcjet. The method advances prior art by providing time-history data over the full ablating surface without targets and without any modifications to the test article. The method is non-intrusive, simple to implement, requires no external light source, and does not interfere with normal operations of the arcjet facility.

  9. Resonant laser ablation: Mechanisms and applications

    SciTech Connect

    Anderson, J.E.; Allen, T.M.; Garrett, A.W.; Gill, C.G.; Hemberger, P.H.; Kelly, P.B.; Nogar, N.S.

    1997-01-01

    We will report on aspects of resonant laser ablation (RLA) behavior for a number of sample types: metals, alloys, thin films, zeolites and soil. The versatility of RLA is demonstrated, with results on a variety of samples and in several mass spectrometers. In addition, the application to depth profiling of thin films is described; absolute removal rates and detection limits are also displayed. A discussion of possible mechanisms for low-power ablation are presented. {copyright} {ital 1997 American Institute of Physics.}

  10. Catheter Ablation of Arrhythmia During Pregnancy.

    PubMed

    Driver, Kevin; Chisholm, Christian A; Darby, Andrew E; Malhotra, Rohit; Dimarco, John P; Ferguson, John D

    2015-06-01

    Cardiac arrhythmia as a complication of pregnancy can be problematic to maternal health and fetal life and development. Catheter ablation of tachyarrhythmias during pregnancy has been successfully performed in selected patients with limited experience. Techniques to limit maternal and fetal radiation exposure, including intracardiac echo and electroanatomic mapping systems, are particularly important in this setting. Specific accommodations are necessary in the care of the gravid patient during catheter ablation. PMID:25828853

  11. Flexible Ablators: Applications and Arcjet Testing

    NASA Technical Reports Server (NTRS)

    Arnold, James O.; Venkatapathy, Ethiraj; Beck, Robin A S.; Mcguire, Kathy; Prabhu, Dinesh K.; Gorbunov, Sergey

    2011-01-01

    Flexible ablators were conceived in 2009 to meet the technology pull for large, human Mars Exploration Class, 23 m diameter hypersonic inflatable aerodynamic decelerators. As described elsewhere, they have been recently undergoing initial technical readiness (TRL) advancement by NASA. The performance limits of flexible ablators in terms of maximum heat rates, pressure and shear remain to be defined. Further, it is hoped that this emerging technology will vastly expand the capability of future NASA missions involving atmospheric entry systems. This paper considers four topics of relevance to flexible ablators: (1) Their potential applications to near/far term human and robotic missions (2) Brief consideration of the balance between heat shield diameter, flexible ablator performance limits, entry vehicle controllability and aft-body shear layer impingement of interest to designers of very large entry vehicles, (3) The approach for developing bonding processes of flexible ablators for use on rigid entry bodies and (4) Design of large arcjet test articles that will enable the testing of flexible ablators in flight-like, combined environments (heat flux, pressure, shear and structural tensile loading). Based on a review of thermal protection system performance requirements for future entry vehicles, it is concluded that flexible ablators have broad applications to conventional, rigid entry body systems and are enabling to large deployable (both inflatable and mechanical) heat shields. Because of the game-changing nature of flexible ablators, it appears that NASA's Office of the Chief Technologist (OCT) will fund a focused, 3-year TRL advancement of the new materials capable of performance in heat fluxes in the range of 200-600 W/sq. cm. This support will enable the manufacture and use of the large-scale arcjet test designs that will be a key element of this OCT funded activity.

  12. Percutaneous ablation of colorectal lung metastases

    PubMed Central

    Solomon, Stephen B.

    2015-01-01

    Lung metastasectomy can prolong survival in patients with metastatic colorectal carcinoma. Thermal ablation offers a potential solution with similar reported survival outcomes. It has minimal effect on pulmonary function, or quality of life, can be repeated, and may be considered more acceptable to patients because of the associated shorter hospital stay and recovery. This review describes the indications, technique, reported outcomes, complications and radiologic appearances after thermal ablation of colorectal lung metastases. PMID:26697202

  13. The clinical implications of elevated blood metal ion concentrations in asymptomatic patients with MoM hip resurfacings: a cohort study

    PubMed Central

    Langton, David J; Sidaginamale, Raghavendra P; Joyce, Thomas J; Natu, Shonali; Blain, Peter; Jefferson, Robert Drysdale; Rushton, Stephen; Nargol, Antoni V F

    2013-01-01

    Objective To determine whether elevated blood cobalt (Co) concentrations are associated with early failure of metal-on-metal (MoM) hip resurfacings secondary to adverse reaction to metal debris (ARMD). Design Cohort study. Setting Single centre orthopaedic unit. Participants Following the identification of complications potentially related to metal wear debris, a blood metal ion screening programme was instigated at our unit in 2007 for all patients with Articular Surface Replacement (ASR) and Birmingham MoM hip resurfacings. Patients were followed annually unless symptoms presented earlier. Symptomatic patients were investigated with ultrasound scan and joint aspiration. The clinical course of all 278 patients with ‘no pain’ or ‘slight/occasional’ pain and a Harris Hip Score greater than or equal to 95 at the time of venesection were documented. A retrospective analysis was subsequently conducted using mixed effect modelling to investigate the temporal pattern of blood Co levels in the patients and survival analysis to investigate the potential role of case demographics and blood Co levels as risk factors for subsequent failure secondary to ARMD. Results Blood Co concentration was a positive and significant risk factor (z=8.44, p=2×10–16) for joint failure, as was the device, where the Birmingham Hip Resurfacing posed a significantly reduced risk for revision by 89% (z=−3.445, p=0.00005 (95% CI on risk 62 to 97)). Analysis using Cox-proportional hazards models indicated that men had a 66% lower risk of joint failure than women (z=−2.29419, p=0.0218, (95% CI on risk reduction 23 to 89)). Conclusions The results suggest that elevated blood metal ion concentrations are associated with early failure of MoM devices secondary to adverse reactions to metal debris. Co concentrations greater than 20 µg/l are frequently associated with metal staining of tissues and the development of osteolysis. Development of soft tissue damage appears to be more complex

  14. Bimodal albedo distributions in the ablation zone of the southwestern Greenland Ice Sheet

    NASA Astrophysics Data System (ADS)

    Moustafa, S. E.; Rennermalm, A. K.; Smith, L. C.; Miller, M. A.; Mioduszewski, J. R.

    2014-09-01

    Surface albedo is a key variable controlling solar radiation absorbed at the Greenland Ice Sheet (GrIS) surface, and thus, meltwater production. Recent decline in surface albedo over the GrIS has been linked to enhanced snow grain metamorphic rates and amplified ice-albedo feedback from atmospheric warming. However, the importance of distinct surface types on ablation zone albedo and meltwater production is still relatively unknown, and excluded in surface mass balance models. In this study, we analyze albedo and ablation rates using in situ and remotely-sensed data. Observations include: (1) a new high-quality in situ spectral albedo dataset collected with an Analytical Spectral Devices (ASD) spectroradiometer measuring at 325-1075 nm, along a 1.25 km transect during three days in June 2013; (2) broadband albedo at two automatic weather stations; and (3) daily MODerate Resolution Imaging Spectroradiometer (MODIS) albedo (MOD10A1) between 31 May and 30 August. We find that seasonal ablation zone albedos have a bimodal distribution, with two alternate states. This suggests that an abrupt switch from high to low albedo can be triggered by a modest melt event, resulting in amplified surface ablation rates. Our results show that such a shift corresponds to an observed melt rate percent difference increase of 51.6% during peak melt season (between 10-14 and 20-24 July 2013). Furthermore, our findings demonstrate that seasonal changes in GrIS ablation zone albedo are not exclusively a function of a darkening surface from ice crystal growth, but rather are controlled by changes in the fractional coverage of snow, bare ice, and impurity-rich surface types. As the climate continues to warm, regional climate models should consider the seasonal evolution of ice surface types in Greenland's ablation zone to improve projections of mass loss contributions to sea level rise.

  15. Bimodal Albedo Distributions in the Ablation Zone of the Southwestern Greenland Ice Sheet

    NASA Astrophysics Data System (ADS)

    Moustafa, S.; Rennermalm, A. K.; Smith, L. C.; Miller, M. A.; Mioduszewski, J.; Koenig, L.

    2014-12-01

    Surface albedo is a key variable controlling solar radiation absorbed at the Greenland Ice Sheet (GrIS) surface, and thus meltwater production. Recent decline in surface albedo over the GrIS has been linked to enhanced snow grain metamorphic rates and amplified ice-albedo feedback from atmospheric warming. However, the importance of distinct surface types on ablation zone albedo and meltwater production is still relatively unknown, and excluded in surface mass balance models. In this study, we analyze albedo and ablation rates (m d-1) using in situ and remotely-sensed data. Observations include: 1) a new high-quality in situ spectral albedo dataset collected with an Analytical Spectral Devices (ASD) spectroradiometer measuring at 325-1075 nm, along a 1.25 km transect during three days in June 2013; 2) broadband albedo at two automatic weather stations; and 3) daily MODerate Resolution Imaging Spectroradiometer (MODIS) albedo (MOD10A1) between 31 May and 30 August. We find that seasonal ablation zone albedos have a bimodal distribution, with two alternate states. This suggests that an abrupt switch from high to low albedo can be triggered by a modest melt event, resulting in amplified ablation rates. Our results show that such a shift corresponds to an observed melt rate percent difference increase of 51.6% during peak melt season (between 10-14 July and 20-24 July, 2013). Furthermore, our findings demonstrate that seasonal changes in GrIS ablation zone albedo are not exclusively a function of a darkening surface from ice crystal growth, but rather are controlled by changes in the fractional coverage of snow, bare ice, and impurity-rich surface types. As the climate continues to warm, regional climate models should consider the seasonal evolution of ice surface types in Greenland's ablation zone to improve projections of mass loss contributions to sea level rise.

  16. Femtosecond laser lithotripsy: feasibility and ablation mechanism

    NASA Astrophysics Data System (ADS)

    Qiu, Jinze; Teichman, Joel M. H.; Wang, Tianyi; Neev, Joseph; Glickman, Randolph D.; Chan, Kin Foong; Milner, Thomas E.

    2010-03-01

    Light emitted from a femtosecond laser is capable of plasma-induced ablation of various materials. We tested the feasibility of utilizing femtosecond-pulsed laser radiation (λ=800 nm, 140 fs, 0.9 mJ/pulse) for ablation of urinary calculi. Ablation craters were observed in human calculi of greater than 90% calcium oxalate monohydrate (COM), cystine (CYST), or magnesium ammonium phosphate hexahydrate (MAPH). Largest crater volumes were achieved on CYST stones, among the most difficult stones to fragment using Holmium:YAG (Ho:YAG) lithotripsy. Diameter of debris was characterized using optical microscopy and found to be less than 20 μm, substantially smaller than that produced by long-pulsed Ho:YAG ablation. Stone retropulsion, monitored by a high-speed camera system with a spatial resolution of 15 μm, was negligible for stones with mass as small as 0.06 g. Peak shock wave pressures were less than 2 bars, measured by a polyvinylidene fluoride (PVDF) needle hydrophone. Ablation dynamics were visualized and characterized with pump-probe imaging and fast flash photography and correlated to shock wave pressures. Because femtosecond-pulsed laser ablates urinary calculi of soft and hard compositions, with micron-sized debris, negligible stone retropulsion, and small shock wave pressures, we conclude that the approach is a promising candidate technique for lithotripsy.

  17. Laser Ablation for Small Hepatocellular Carcinoma

    PubMed Central

    Pacella, Claudio Maurizio; Francica, Giampiero; Di Costanzo, Giovanni Giuseppe

    2011-01-01

    Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide and is increasingly detected at small size (<5 cm) owing to surveillance programmes in high-risk patients. For these cases, curative therapies such as resection, liver transplantation, or percutaneous ablation have been proposed. When surgical options are precluded, image-guided tumor ablation is recommended as the most appropriate therapeutic choice in terms of tumor local control, safety, and improvement in survival. Laser ablation (LA) represents one of currently available loco-ablative techniques: light is delivered via flexible quartz fibers of diameter from 300 to 600 μm inserted into tumor lesion through either fine needles (21g Chiba needles) or large-bore catheters. The thermal destruction of tissue is achieved through conversion of absorbed light (usually infrared) into heat. A range of different imaging modalities have been used to guide percutaneous laser ablation, but ultrasound and magnetic resonance imaging are most widely employed, according to local experience and resource availability. Available clinical data suggest that LA is highly effective in terms of tumoricidal capability with an excellent safety profile; the best results in terms of long-term survival are obtained in early HCC so that LA can be proposed not only in unresectable cases but, not differently from radiofrequency ablation, also as the first-line treatment. PMID:22191028

  18. Basic ablation phenomena during laser thrombolysis

    NASA Astrophysics Data System (ADS)

    Sathyam, Ujwal S.; Shearin, Alan; Prahl, Scott A.

    1997-05-01

    This paper presents studies of microsecond ablation phenomena that take place during laser thrombolysis. The main goals were to optimize laser parameters for efficient ablation, and to investigate the ablation mechanism. Gelatin containing an absorbing dye was used as the clot model. A parametric study was performed to identify the optimal wavelength, spot size, pulse energies, and repetition rate for maximum material removal. The minimum radiant exposures to achieve ablation at any wavelength were measured. The results suggest that most visible wavelengths were equally efficient at removing material at radiant exposures above threshold. Ablation was initiated at surface temperatures just above 100 degrees Celsius. A vapor bubble was formed during ablation. Less than 5% of the total pulse energy is coupled into the bubble energy. A large part of the delivered energy is unaccounted for and is likely released partly as acoustic transients from the vapor expansion and partly wasted as heat. The current laser and delivery systems may not be able to completely remove large clot burden that is sometimes encountered in heart attacks. However, laser thrombolysis may emerge as a favored treatment for strokes where the occlusion is generally smaller and rapid recanalization is of paramount importance. A final hypothesis is that laser thrombolysis should be done at radiant exposures close to threshold to minimize any damaging effects of the bubble dynamics on the vessel wall.

  19. Novel Laser Ablation Technology for Surface Decontamination

    SciTech Connect

    Cheng, Chung H.

    2004-06-01

    Laser ablation for surface cleaning has been pursued for the removal of paint on airplanes. It has also been pursued for the cleaning of semiconductor surfaces. However, all these approaches have been pursued by laser ablation in air. For highly contaminated surface, laser ablation in air can easily cause secondary contamination. Thus it is not suitable to apply to achieve surface decontamination for DOE facilities since many of these facilities have radioactive contaminants on the surface. Any secondary contamination will be a grave concern. The objective of this project is to develop a novel technology for laser ablation in liquid for surface decontamination. It aims to achieve more efficient surface decontamination without secondary contamination and to evaluate the economic feasibility for large scale surface decontamination with laser ablation in liquid. When laser ablation is pursued in the solution, all the desorbed contaminants will be confined in liquid. The contaminants can be precipitated and subsequently contained in a small volume for disposal. It can reduce the risk of the decontamination workers. It can also reduce the volume of contaminants dramatically.

  20. Lung Cancer Ablation: What Is the Evidence?

    PubMed Central

    de Baere, Thierry; Farouil, Geoffroy; Deschamps, Frederic

    2013-01-01

    Percutaneous ablation of small non-small cell lung cancer (NSCLC) has been demonstrated to be both feasible and safe in nonsurgical candidates. Radiofrequency ablation (RFA), the most commonly used technique for ablation, has a reported rate of complete ablation of ~90%, with best results obtained in tumors <2 to 3 cm in diameter. The best reported 1-, 3-, and 5-year overall survival rates after RFA of NSCLC are 97.7%, 72.9%, and 55.7%, respectively. It is noteworthy that in most studies, cancer-specific survival is greater than overall survival due to severe comorbidities in patients treated with RFA for NSCLC. Aside from tumor size and tumor stage, these comorbidities are predictive of survival. Other ablation techniques such as microwave and irreversible electroporation may in the future prove to overcome some of the limitations of RFA, namely for large tumors or tumors close to large vessels. Stereotactic body radiation therapy has also been demonstrated to be highly efficacious in treating small lung tumors and will need to be compared with percutaneous ablation. This article reviews the current evidence regarding RFA for lung cancer. PMID:24436531

  1. Compartment ablation analysis of the insulin-responsive glucose transporter (GLUT4) in 3T3-L1 adipocytes.

    PubMed Central

    Livingstone, C; James, D E; Rice, J E; Hanpeter, D; Gould, G W

    1996-01-01

    The translocation of a unique facilitative glucose transporter isoform (GLUT4) from an intracellular site to the plasma membrane accounts for the large insulin-dependent increase in glucose transport observed in muscle and adipose tissue. The intracellular location of GLUT4 in the basal state and the pathway by which it reaches the cell surface upon insulin stimulation are unclear. Here, we have examined the colocalization of GLUT4 with the transferrin receptor, a protein which is known to recycle through the endosomal system. Using an anti-GLUT4 monoclonal antibody we immunoisolated a vesicular fraction from an intracellular membrane fraction of 3T3-L1 adipocytes that contained > 90% of the immunoreactive GLUT4 found in this fraction, but only 40% of the transferrin receptor (TfR). These results suggest only a limited degree of colocalization of these proteins. Using a technique to cross-link and render insoluble ("ablate') intracellular compartments containing the TfR by means of a transferrin-horseradish peroxidase conjugate (Tf-HRP), we further examined the relationship between the endosomal recycling pathway and the intracellular compartment containing GLUT4 in these cells. Incubation of non-stimulated cells with Tf-HRP for 3 h at 37 degrees C resulted in quantitative ablation of the intracellular TfR, GLUT1 and mannose-6-phosphate receptor and a shift in the density of Rab5-positive membranes. In contrast, only 40% of intracellular GLUT4 was ablated under the same conditions. Ablation was specific for the endosomal system as there was no significant ablation of either TGN38 or lgp120, which are markers for the trans Golgi reticulum and lysosomes respectively. Subcellular fractionation analysis revealed that most of the ablated pools of GLUT4 and TfR were found in the intracellular membrane fraction. The extent of ablation of GLUT4 from the intracellular fraction was unchanged in cells which were insulin-stimulated prior to ablation, whereas GLUT1 exhibited

  2. Percutaneous Radiofrequency Ablation for Treatment of Recurrent Retroperitoneal Liposarcoma

    SciTech Connect

    Keil, Sebastian Bruners, Philipp; Brehmer, Bernhard; Mahnken, Andreas Horst

    2008-07-15

    Percutaneous CT-guided radiofrequency ablation (RFA) is becoming more and more established in the treatment of various neoplasms, including retroperitoneal tumors of the kidneys and the adrenal glands. We report the case of RFA in a patient suffering from the third relapse of a retroperitoneal liposarcoma in the left psoas muscle. After repeated surgical resection and supportive radiation therapy of a primary retroperitoneal liposarcoma and two surgically treated recurrences, including replacement of the ureter by a fraction of the ileum, there was no option for further surgery. Thus, we considered RFA as the most suitable treatment option. Monopolar RFA was performed in a single session with a 2-cm umbrella-shaped LeVeen probe. During a 27-month follow-up period the patient remained free of tumor.

  3. Plans and status of the Beryllium ablator campaign on NIF

    NASA Astrophysics Data System (ADS)

    Kline, J. L.; Yi, S. A.; Simakov, A. N.; Wilson, D. C.; Olson, R. E.; Krasheninnikova, N. S.; Kyrala, G. A.; Perry, T. S.; Batha, S. H.; Dewald, E. L.; Edwards, M. J.; MacKinnon, A. J.; Meezan, N. B.

    2014-10-01

    Beryllium has long been known to have excellent properties for indirectly driven ICF implosions including enhanced ablation pressure, implosion velocity, and mass ablation rate. The high ablation velocity leads to stabilization of ablative hydrodynamic instabilities and higher ablation pressures. Recent ``high foot'' experiments have shown ablative Rayleigh-Taylor to be a leading cause of degraded performance for ICF implosions. While Beryllium ablators have these advantages, there are also risks associated with Beryllium target designs. A campaign is underway to design and to test these advantages for comparison with other ablator options and determine which provides the best path forward for ICF. Experiments using Beryllium ablators are expected to start in the late summer of 2014. This presentation will discuss the status of the experiments and layout the plans/goals for the campaign. This work is supported by the US DOE.

  4. Magnetocardiographically-guided catheter ablation.

    PubMed

    Fenici, R R; Covino, M; Cellerino, C; Di Lillo, M; De Filippo, M C; Melillo, G

    1995-12-01

    After more than 30 years since the first magnetocardiographic (MCG) recording was carried out with induction coils, MCG is now approaching the threshold of clinical use. During the last 5 years, in fact, there has been a growing interest of clinicians in this new method which provides an unrivalled accuracy for noninvasive, three-dimensional localization of intracardiac source. An increasing number of laboratories are reporting data validating the use of MCG as an effective method for preoperative localization of arrhythmogenic substrates and for planning the best catheter ablation approach for different arrhythmogenic substrates. In this article, available data from literature have been reviewed. We consider the clinical use of MCG to localize arrhythmogenic substrates in patients with Wolff-Parkinson-White syndrome and in patients with ventricular tachycardia in order to assess the state-of-the-art of the method on a large number of patients. This article also addresses some suggestions for industrial development of more compact, medically oriented MCG equipments at reasonable cost. PMID:10159774

  5. Lip Reconstruction after Tumor Ablation

    PubMed Central

    Ebrahimi, Ali; Kalantar Motamedi, Mohammad Hossein; Ebrahimi, Azin; Kazemi, Mohammad; Shams, Amin; Hashemzadeh, Haleh

    2016-01-01

    Approximately 25% of all oral cavity carcinomas involve the lips, and the primary management of these lesions is complete surgical resection. Loss of tissue in the lips after resection is treated with a variety of techniques, depending on the extension and location of the defect. Here we review highly accepted techniques of lip reconstruction and some of new trials with significant clinical results. Reconstruction choice is primarily depend to size of the defect, localization of defect, elasticity of tissues. But patient’s age, comorbidities, and motivation are also important. According to the defect location and size, different reconstruction methods can be used. For defects involved less than 30% of lips, primary closures are sufficient. In defects with 35–70% lip involvement, the Karapandzic, Abbe, Estlander, McGregor or Gillies’ fan flaps or their modifications can be used. When lip remaining tissues are insufficient, cheek tissue can be used in Webster and Bernard advancement flaps and their various modifications. Deltopectoral or radial forearm free flaps can be options for large defects of the lip extending to the Jaws. To achieve best functional and esthetic results, surgeons should be able to choose most appropriate reconstruction method. Considering defects’ size and location, patients’ expects and surgeon’s ability and knowledge, a variety of flaps are presented in order to reconstruct defects resulted from tumor ablation. It’s necessary for surgeons to trace the recent innovations in lip reconstruction to offer best choices to patients. PMID:27308236

  6. Dust Ablation in Pluto's Atmosphere

    NASA Astrophysics Data System (ADS)

    Horanyi, M.; Poppe, A. R.; Sternovsky, Z.

    2015-12-01

    Based on measurements by in situ dust detectors onboard the Pioneer and New Horizon spacecraft the total production rate of dust particles born in the Kuiper belt can be estimated to be on the order of 5 x 10 ^3 kg/s in the approximate size range of 1 - 10 micron. These particles slowly migrate inward due to Poynting - Robertson drag and their spatial distribution is shaped by mean motion resonances with the gas giant planets in the outer solar system. The expected mass influx into Pluto's atmosphere is on the order of 50 kg/day, and the arrival speed of the incoming particles is on the order of 3 - 4 km/s. We have followed the ablation history as function of speed and size of dust particles in Pluto's atmosphere, and found that, if the particles are rich in volatiles, they can fully sublimate due to drag heating and deposit their mass in a narrow layer. This deposition might promote the formation of the haze layers observed by the New Horizons spacecraft. This talk will explore the constraints on the composition of the dust particles, as well as on our newly developed models of Pluto's atmosphere that can be learned by matching the altitude where haze layers could be formed.

  7. Dust ablation in Pluto's atmosphere

    NASA Astrophysics Data System (ADS)

    Horanyi, Mihaly; Poppe, Andrew; Sternovsky, Zoltan

    2016-04-01

    Based on measurements by dust detectors onboard the Pioneer 10/11 and New Horizons spacecraft the total production rate of dust particles born in the Edgeworth Kuiper Belt (EKB) has been be estimated to be on the order of 5 ṡ 103 kg/s in the approximate size range of 1 - 10 μm. Dust particles are produced by collisions between EKB objects and their bombardment by both interplanetary and interstellar dust particles. Dust particles of EKB origin, in general, migrate towards the Sun due to Poynting-Robertson drag but their distributions are further sculpted by mean-motion resonances as they first approach the orbit of Neptune and later the other planets, as well as mutual collisions. Subsequently, Jupiter will eject the vast majority of them before they reach the inner solar system. The expected mass influx into Pluto atmosphere is on the order of 200 kg/day, and the arrival speed of the incoming particles is on the order of 3 - 4 km/s. We have followed the ablation history as function of speed and size of dust particles in Pluto's atmosphere, and found that volatile rich particles can fully sublimate due to drag heating and deposit their mass in narrow layers. This deposition might promote the formation of the haze layers observed by the New Horizons spacecraft. This talk will explore the constraints on the composition of the dust particles by comparing the altitude of the deposition layers to the observed haze layers.

  8. A systematic review of surgical ablation versus catheter ablation for atrial fibrillation

    PubMed Central

    Kearney, Katherine; Stephenson, Rowan; Phan, Kevin; Chan, Wei Yen; Huang, Min Yin

    2014-01-01

    Background Atrial fibrillation (AF) is an increasingly prevalent condition in the ageing population, with significantly associated morbidity and mortality. Surgical and catheter ablative strategies both aim to reduce mortality and morbidity through freedom from AF. This review consolidates all currently available comparative data to evaluate these two interventions. Methods A systematic search was conducted across MEDLINE, PubMed, Embase, Cochrane Central Register of Controlled Trials and the Cochrane Database of Systematic Reviews from January 2000 until August 2013. All studies were critically appraised and only those directly comparing surgical and catheter ablation were included. Results Seven studies were deemed suitable for analysis according to the inclusion criteria. Freedom from AF was significantly higher in the surgical ablation group versus the catheter ablation group at 6-month, 12-month and study endpoint follow-up periods. Subgroup analysis demonstrated similar trends, with higher freedom from AF in the surgical ablation group for paroxysmal AF patients. The incidence of pacemaker implantation was higher, while no difference in stroke or cardiac tamponade was demonstrated for the surgical versus catheter ablation groups. Conclusions Current evidence suggests that epicardial ablative strategies are associated with higher freedom from AF, higher pacemaker implantation rates and comparable neurological complications and cardiac tamponade incidence to catheter ablative treatment. Other complications and risks were poorly reported, which warrants further randomized controlled trials (RCTs) of adequate power and follow-up duration. PMID:24516794

  9. Quantification and controllability study of minimally invasive exothermic chemo-ablation therapy for tumor ablation.

    PubMed

    Liu, Ran; Huang, Yu; Liu, Jing

    2009-01-01

    The recently proposed exothermic chemical reaction based tumor hyperthermia method presented a new way of realizing truly minimally invasive treatment for tumor. This method utilizes heat generated from the reaction between acid and alkali solutions to allow for tumor ablation. Successful clinical implementation of this method requires a clearer understanding and quantification of the ablation area such that a more controllable operation can be made. A number of in-vitro and in-vivo experiments are designed to examine the features of thermal chemo-ablation therapy which include micro and macro characteristics of ablated tissue and temperature change during the ablation process. A Quantitative study on the relationship between velocity and ablation volume as well as a Graphical User Interface in Matlab for computerized ablation area analysis are also presented in this article. We present in here two instrument designs for thermal chemo-ablation and have completed the prototype design for the injection pump which has been tested and successfully applied in ex-vivo and vivo experiments. PMID:19963802

  10. Optimal acetabular component orientation estimated using edge-loading and impingement risk in patients with metal-on-metal hip resurfacing arthroplasty.

    PubMed

    Mellon, Stephen J; Grammatopoulos, George; Andersen, Michael S; Pandit, Hemant G; Gill, Harinderjit S; Murray, David W

    2015-01-21

    Edge-loading in patients with metal-on-metal resurfaced hips can cause high serum metal ion levels, the development of soft-tissue reactions local to the joint called pseudotumours and ultimately, failure of the implant. Primary edge-loading is where contact between the femoral and acetabular components occurs at the edge/rim of the acetabular component whereas impingement of the femoral neck on the acetabular component's edge causes secondary or contrecoup edge-loading. Although the relationship between the orientation of the acetabular component and primary edge-loading has been identified, the contribution of acetabular component orientation to impingement and secondary edge-loading is less clear. Our aim was to estimate the optimal acetabular component orientation for 16 metal-on-metal hip resurfacing arthroplasty (MoMHRA) subjects with known serum metal ion levels. Data from motion analysis, subject-specific musculoskeletal modelling and Computed Tomography (CT) measurements were used to calculate the dynamic contact patch to rim (CPR) distance and impingement risk for 3416 different acetabular component orientations during gait, sit-to-stand, stair descent and static standing. For each subject, safe zones free from impingement and edge-loading (CPR <10%) were defined and, consequently, an optimal acetabular component orientation was determined (mean inclination 39.7° (SD 6.6°) mean anteversion 14.9° (SD 9.0°)). The results of this study suggest that the optimal acetabular component orientation can be determined from a patient's motion and anatomy. However, 'safe' zones of acetabular component orientation associated with reduced risk of dislocation and pseudotumour are also associated with a reduced risk of edge-loading and impingement. PMID:25482661

  11. Factors Limiting Complete Tumor Ablation by Radiofrequency Ablation

    SciTech Connect

    Paulet, Erwan Aube, Christophe; Pessaux, Patrick; Lebigot, Jerome; Lhermitte, Emilie; Oberti, Frederic; Ponthieux, Anne; Cales, Paul; Ridereau-Zins, Catherine; Pereira, Philippe L.

    2008-01-15

    The purpose of this study was to determine radiological or physical factors to predict the risk of residual mass or local recurrence of primary and secondary hepatic tumors treated by radiofrequency ablation (RFA). Eighty-two patients, with 146 lesions (80 hepatocellular carcinomas, 66 metastases), were treated by RFA. Morphological parameters of the lesions included size, location, number, ultrasound echogenicity, computed tomography density, and magnetic resonance signal intensity were obtained before and after treatment. Parameters of the generator were recorded during radiofrequency application. The recurrence-free group was statistically compared to the recurrence and residual mass groups on all these parameters. Twenty residual masses were detected. Twenty-nine lesions recurred after a mean follow-up of 18 months. Size was a predictive parameter. Patients' sex and age and the echogenicity and density of lesions were significantly different for the recurrence and residual mass groups compared to the recurrence-free group (p < 0.05). The presence of an enhanced ring on the magnetic resonance control was more frequent in the recurrence and residual mass groups. In the group of patients with residual lesions, analysis of physical parameters showed a significant increase (p < 0.05) in the time necessary for the temperature to rise. In conclusion, this study confirms risk factors of recurrence such as the size of the tumor and emphasizes other factors such as a posttreatment enhanced ring and an increase in the time necessary for the rise in temperature. These factors should be taken into consideration when performing RFA and during follow-up.

  12. Ultraviolet femtosecond and nanosecond laser ablation of silicon: Ablation efficiency and laser-induced plasma expansion

    SciTech Connect

    Zeng, Xianzhong; Mao, Xianglei; Greif, Ralph; Russo, Richard E.

    2004-03-23

    Femtosecond laser ablation of silicon in air was studied and compared with nanosecond laser ablation at ultraviolet wavelength (266 nm). Laser ablation efficiency was studied by measuring crater depth as a function of pulse number. For the same number of laser pulses, the fs-ablated crater was about two times deeper than the ns-crater. The temperature and electron number density of the pulsed laser-induced plasma were determined from spectroscopic measurements. The electron number density and temperature of fs-pulse plasmas decreased faster than ns-pulse plasmas due to different energy deposition mechanisms. Images of the laser-induced plasma were obtained with femtosecond time-resolved laser shadowgraph imaging. Plasma expansion in both the perpendicular and the lateral directions to the laser beam were compared for femtosecond and nanosecond laser ablation.

  13. Ablation enhancement of silicon by ultrashort double-pulse laser ablation

    SciTech Connect

    Zhao, Xin; Shin, Yung C.

    2014-09-15

    In this study, the ultrashort double-pulse ablation of silicon is investigated. An atomistic simulation model is developed to analyze the underlying physics. It is revealed that the double-pulse ablation could significantly increase the ablation rate of silicon, compared with the single pulse ablation with the same total pulse energy, which is totally different from the case of metals. In the long pulse delay range (over 1 ps), the enhancement is caused by the metallic transition of melted silicon with the corresponding absorption efficiency. At ultrashort pulse delay (below 1 ps), the enhancement is due to the electron excitation by the first pulse. The enhancement only occurs at low and moderate laser fluence. The ablation is suppressed at high fluence due to the strong plasma shielding effect.

  14. Dividing Fractions: A Pedagogical Technique

    ERIC Educational Resources Information Center

    Lewis, Robert

    2016-01-01

    When dividing one fraction by a second fraction, invert, that is, flip the second fraction, then multiply it by the first fraction. To multiply fractions, simply multiply across the denominators, and multiply across the numerators to get the resultant fraction. So by inverting the division of fractions it is turned into an easy multiplication of…

  15. Photoacoustic characterization of radiofrequency ablation lesions

    NASA Astrophysics Data System (ADS)

    Bouchard, Richard; Dana, Nicholas; Di Biase, Luigi; Natale, Andrea; Emelianov, Stanislav

    2012-02-01

    Radiofrequency ablation (RFA) procedures are used to destroy abnormal electrical pathways in the heart that can cause cardiac arrhythmias. Current methods relying on fluoroscopy, echocardiography and electrical conduction mapping are unable to accurately assess ablation lesion size. In an effort to better visualize RFA lesions, photoacoustic (PA) and ultrasonic (US) imaging were utilized to obtain co-registered images of ablated porcine cardiac tissue. The left ventricular free wall of fresh (i.e., never frozen) porcine hearts was harvested within 24 hours of the animals' sacrifice. A THERMOCOOLR Ablation System (Biosense Webster, Inc.) operating at 40 W for 30-60 s was used to induce lesions through the endocardial and epicardial walls of the cardiac samples. Following lesion creation, the ablated tissue samples were placed in 25 °C saline to allow for multi-wavelength PA imaging. Samples were imaged with a VevoR 2100 ultrasound system (VisualSonics, Inc.) using a modified 20-MHz array that could provide laser irradiation to the sample from a pulsed tunable laser (Newport Corp.) to allow for co-registered photoacoustic-ultrasound (PAUS) imaging. PA imaging was conducted from 750-1064 nm, with a surface fluence of approximately 15 mJ/cm2 maintained during imaging. In this preliminary study with PA imaging, the ablated region could be well visualized on the surface of the sample, with contrasts of 6-10 dB achieved at 750 nm. Although imaging penetration depth is a concern, PA imaging shows promise in being able to reliably visualize RF ablation lesions.

  16. Radioiodine Remnant Ablation: A Critical Review

    PubMed Central

    Bal, Chandra Sekhar; Padhy, Ajit Kumar

    2015-01-01

    Radioiodine remnant ablation (RRA) is considered a safe and effective method for eliminating residual thyroid tissue, as well as microscopic disease if at all present in thyroid bed following thyroidectomy. The rationale of RRA is that in the absence of thyroid tissue, serum thyroglobulin (Tg) measurement can be used as an excellent tumor marker. Other considerations are like the presence of significant remnant thyroid tissue makes detection and treatment of nodal or distant metastases difficult. Rarely, microscopic disease in the thyroid bed if not ablated, in the future, could be a source of anaplastic transformation. On the other hand, microscopic tumor emboli in distant sites could be the cause of distant metastasis too. The ablation of remnant tissue would in all probability eliminate these theoretical risks. It may be noted that all these are unproven contentious issues except postablation serum Tg estimation that could be a good tumor marker for detecting early biochemical recurrence in long-term follow-up strategy. Radioactive iodine is administered as a form of “adjuvant therapy” for remnant ablation. There have been several reports with regard to the administered dose for remnant ablation. The first report of a prospective randomized clinical trial was published from India by a prospective randomized study conducted at the All India Institute of Medical Sciences, New Delhi in the year 1996. The study reported that increasing the empirical 131I initial dose to more than 50 mCi results in plateauing of the dose-response curve and thus, conventional high-dose remnant ablation needs critical evaluation. Recently, two important studies were published: One from French group and the other from UK on a similar line. Interestingly, all three studies conducted in three different geographical regions of the world showed exactly similar conclusion. The new era of low-dose remnant ablation has taken a firm scientific footing across the continents. PMID:26420983

  17. Subsurface ablation of atherosclerotic plaque using ultrafast laser pulses

    PubMed Central

    Lanvin, Thomas; Conkey, Donald B.; Frobert, Aurelien; Valentin, Jeremy; Goy, Jean-Jacques; Cook, Stéphane; Giraud, Marie-Noelle; Psaltis, Demetri

    2015-01-01

    We perform subsurface ablation of atherosclerotic plaque using ultrafast pulses. Excised mouse aortas containing atherosclerotic plaque were ablated with ultrafast near-infrared (NIR) laser pulses. Optical coherence tomography (OCT) was used to observe the ablation result, while the physical damage was inspected in histological sections. We characterize the effects of incident pulse energy on surface damage, ablation hole size, and filament propagation. We find that it is possible to ablate plaque just below the surface without causing surface damage, which motivates further investigation of ultrafast ablation for subsurface atherosclerotic plaque removal. PMID:26203381

  18. Clinical Significance of Additional Ablation of Atrial Premature Beats after Catheter Ablation for Atrial Fibrillation

    PubMed Central

    Kim, In-Soo; Yang, Pil-Sung; Kim, Tae-Hoon; Park, Junbeum; Park, Jin-Kyu; Uhm, Jae Sun; Joung, Boyoung; Lee, Moon Hyoung

    2016-01-01

    Purpose The clinical significance of post-procedural atrial premature beats immediately after catheter ablation for atrial fibrillation (AF) has not been clearly determined. We hypothesized that the provocation of immediate recurrence of atrial premature beats (IRAPB) and additional ablation improves the clinical outcome of AF ablation. Materials and Methods We enrolled 200 patients with AF (76.5% males; 57.4±11.1 years old; 64.3% paroxysmal AF) who underwent catheter ablation. Post-procedure IRAPB was defined as frequent atrial premature beats (≥6/min) under isoproterenol infusion (5 µg/min), monitored for 10 min after internal cardioversion, and we ablated mappable IRAPBs. Post-procedural IRAPB provocations were conducted in 100 patients. We compared the patients who showed IRAPB with those who did not. We also compared the IRAPB provocation group with 100 age-, sex-, and AF-type-matched patients who completed ablation without provocation (No-Test group). Results 1) Among the post-procedural IRAPB provocation group, 33% showed IRAPB and required additional ablation with a longer procedure time (p=0.001) than those without IRAPB, without increasing the complication rate. 2) During 18.0±6.6 months of follow-up, the patients who showed IRAPB had a worse clinical recurrence rate than those who did not (27.3% vs. 9.0%; p=0.016), in spite of additional IRAPB ablation. 3) However, the clinical recurrence rate was significantly lower in the IRAPB provocation group (15.0%) than in the No-Test group (28.0%; p=0.025) without lengthening of the procedure time or raising complication rate. Conclusion The presence of post-procedural IRAPB was associated with a higher recurrence rate after AF ablation. However, IRAPB provocation and additional ablation might facilitate a better clinical outcome. A further prospective randomized study is warranted. PMID:26632385

  19. Ablation threshold and ablation mechanism transition of polyoxymethylene irradiated by CO2 laser.

    PubMed

    Li, Gan; Cheng, Mousen; Li, Xiaokang

    2016-09-01

    Polyoxymethylene (POM) decomposes gradually as it is heated up by the irradiation of CO2 laser; the long-chain molecules of POM are broken into short chains, which leads to the lowering of the melting point and the critical temperature of the ablation products. When the product temperature is above the melting point, ablation comes up in the way of vaporization; when the product temperature is higher than the critical temperature, all liquid products are transformed into gas instantly and the ablation mechanism is changed. The laser fluence at which significant ablation is observed is defined as the ablation threshold, and the fluence corresponding to the ablation mechanism changing is denoted as the flyover threshold. In this paper, random pyrolysis is adopted to describe the pyrolytic decomposition of POM, and consequently, the components of the pyrolysis products under different pyrolysis rates are acquired. The Group Contribution method is used to count the thermodynamic properties of the pyrolysis products, and the melting point and the critical temperature of the product mixture are obtained by the Mixing Law. The Knudsen layer relationship is employed to evaluate the ablation mass removal when the product temperature is below the critical temperature. The gas dynamics conservation laws associated with the Jouguet condition are used to calculate the mass removal when the product temperature is higher than the critical temperature. Based on the model, a set of simulations for various laser intensities and lengths are carried out to generalize the relationships between the thresholds and the laser parameters. Besides the ablated mass areal density, which fits the experimental data quite well, the ablation temperature, pyrolysis rate, and product components are also discussed for a better understanding of the ablation mechanism of POM. PMID:27607281

  20. Prospective study of left ventricular function after radiofrequency ablation of atrioventricular junction in patients with atrial fibrillation.

    PubMed Central

    Edner, M.; Caidahl, K.; Bergfeldt, L.; Darpö, B.; Edvardsson, N.; Rosenqvist, M.

    1995-01-01

    BACKGROUND--In patients with drug resistant incessant supraventricular tachycardia, radiofrequency induced ablation of the atrioventricular junction and pacemaker implantation have hitherto been considered a treatment of last resort. OBJECTIVE--To assess the short and long term effects of ablation of the atrioventricular junction on systolic and diastolic left ventricular function in patients with atrial fibrillation with and without impaired left ventricular function. PATIENTS--29 patients (19 men; mean age 65 (SD 7) years (range 50-76)) undergoing ablation of the atrioventricular junction for drug refractory atrial fibrillation were examined a mean of 2, 65, and 216 days after ablation of the bundle of His. MAIN OUTCOME MEASURES--Left ventricular ejection fraction and early filling deceleration times (Edec) were assessed by Doppler echocardiography after 1 to 2 hours of ventricular pacing at a rate of 80 beats/minute. RESULTS--In 14 patients with a left ventricular ejection fraction < 50% left ventricular ejection fraction increased significantly from 32% (11%) to 39% (11%) (65 days) and 45% (11%) (216 days) (P < 0.001); Edec increased from 142 (46) ms to 169 (57) ms (65 days) and 167 (56) ms (216 days) (P < 0.05). In 15 patients with an ejection fraction > or = 50% at the initial examination no significant change in systolic function was observed. CONCLUSIONS--In patients with left ventricular dysfunction long term improvement of systolic and diastolic left ventricular function was seen after ablation of the atrioventricular junction for rate control of atrial fibrillation. This procedure had no adverse effects on normal left ventricular function. PMID:7547020

  1. FRACTIONAL PEARSON DIFFUSIONS

    PubMed Central

    Leonenko, Nikolai N.; Meerschaert, Mark M.

    2013-01-01

    Pearson diffusions are governed by diffusion equations with polynomial coefficients. Fractional Pearson diffusions are governed by the corresponding time-fractional diffusion equation. They are useful for modeling sub-diffusive phenomena, caused by particle sticking and trapping. This paper provides explicit strong solutions for fractional Pearson diffusions, using spectral methods. It also presents stochastic solutions, using a non-Markovian inverse stable time change. PMID:23626377

  2. Effect of Laser Wavelength and Ablation Time on Pulsed Laser Ablation Synthesis of AL Nanoparticles in Ethanol

    NASA Astrophysics Data System (ADS)

    Baladi, A.; Mamoory, R. Sarraf

    Aluminum nanoparticles were synthesized by pulsed laser ablation of Al targets in ethanol for 5-15 minutes using the 1064 and 533 nm wavelengths of a Nd:YAG laser with energies of 280-320 mJ per pulse. It has been found that higher wavelength leads to significantly higher ablation efficiency, and finer spherical nanoparticles are also synthesized. Besides, it was obvious that higher ablation time resulted in higher ablated mass, while lower ablation rate was observed. Finer nanoparticles, moreover, are synthesized in higher ablation times.

  3. Fracture in Phenolic Impregnated Carbon Ablator

    NASA Technical Reports Server (NTRS)

    Agrawal, Parul; Chavez-Garcia, Jose; Pham, John

    2013-01-01

    This paper describes the development of a novel technique to understand the failure mechanisms inside thermal protection materials. The focus of this research is on the class of materials known as phenolic impregnated carbon ablators. It has successfully flown on the Stardust spacecraft and is the thermal protection system material chosen for the Mars Science Laboratory and SpaceX Dragon spacecraft. Although it has good thermal properties, structurally, it is a weak material. To understand failure mechanisms in carbon ablators, fracture tests were performed on FiberForm(Registered TradeMark) (precursor), virgin, and charred ablator materials. Several samples of these materials were tested to investigate failure mechanisms at a microstructural scale. Stress-strain data were obtained simultaneously to estimate the tensile strength and toughness. It was observed that cracks initiated and grew in the FiberForm when a critical stress limit was reached such that the carbon fibers separated from the binder. However, both for virgin and charred carbon ablators, crack initiation and growth occurred in the matrix (phenolic) phase. Both virgin and charred carbon ablators showed greater strength values compared with FiberForm samples, confirming that the presence of the porous matrix helps in absorbing the fracture energy.

  4. Design Calculations for NIF Convergent Ablator Experiments

    NASA Astrophysics Data System (ADS)

    Olson, R. E.; Callahan, D. A.; Hicks, D. G.; Landen, O. L.; Langer, S. H.; Meezan, N. B.; Spears, B. K.; Widmann, K.; Kline, J. L.; Wilson, D. C.; Petrasso, R. D.; Leeper, R. J.

    2010-11-01

    Design calculations for NIF convergent ablator experiments will be described. The convergent ablator experiments measure the implosion trajectory, velocity, and ablation rate of an x-ray driven capsule and are a important component of the U. S. National Ignition Campaign at NIF. The design calculations are post-processed to provide simulations of the key diagnostics -- 1) Dante measurements of hohlraum x-ray flux and spectrum, 2) streaked radiographs of the imploding ablator shell, 3) wedge range filter measurements of D-He3 proton output spectra, and 4) GXD measurements of the imploded core. The simulated diagnostics will be compared to the experimental measurements to provide an assessment of the accuracy of the design code predictions of hohlraum radiation temperature, capsule ablation rate, implosion velocity, shock flash areal density, and x-ray bang time. Post-shot versions of the design calculations are used to enhance the understanding of the experimental measurements and will assist in choosing parameters for subsequent shots and the path towards optimal ignition capsule tuning. *SNL, LLNL, and LANL are operated under US DOE contracts DE-AC04-94AL85000. DE-AC52-07NA27344, and DE-AC04-94AL85000.

  5. Design calculations for NIF convergent ablator experiments.

    SciTech Connect

    Callahan, Debra; Leeper, Ramon Joe; Spears, B. K.; Zylstra, A.; Seguin, F.; Landen, Otto L.; Petrasso, R. D.; Rinderknecht, H.; Kline, J. L.; Frenje, J.; Wilson, D. C.; Langer, S. H.; Widmann, K.; Meezan, Nathan B.; Hicks, Damien G.; Olson, Richard Edward

    2010-11-01

    Design calculations for NIF convergent ablator experiments will be described. The convergent ablator experiments measure the implosion trajectory, velocity, and ablation rate of an x-ray driven capsule and are a important component of the U. S. National Ignition Campaign at NIF. The design calculations are post-processed to provide simulations of the key diagnostics: (1) Dante measurements of hohlraum x-ray flux and spectrum, (2) streaked radiographs of the imploding ablator shell, (3) wedge range filter measurements of D-He3 proton output spectra, and (4) GXD measurements of the imploded core. The simulated diagnostics will be compared to the experimental measurements to provide an assessment of the accuracy of the design code predictions of hohlraum radiation temperature, capsule ablation rate, implosion velocity, shock flash areal density, and x-ray bang time. Post-shot versions of the design calculations are used to enhance the understanding of the experimental measurements and will assist in choosing parameters for subsequent shots and the path towards optimal ignition capsule tuning.

  6. Improved laser ablation model for asteroid deflection

    NASA Astrophysics Data System (ADS)

    Vasile, Massimiliano; Gibbings, Alison; Watson, Ian; Hopkins, John-Mark

    2014-10-01

    This paper presents an improved laser ablation model and compares the performance - momentum coupling and deflection system mass - of laser ablation against contactless deflection methods based on ion-propulsion. The deflection of an asteroid through laser ablation is achieved by illuminating the surface of the asteroid with high intensity laser light. The absorbed energy induces the sublimation of the surface material and the generation of a plume of gas and ejecta. Similar to a rocket engine, the flow of expelled material produces a continuous and controllable thrust that could be used to modify the trajectory and tumbling motion of the asteroid. Recent results gained from a series of laser ablation experiments were used to improve the sublimation and deflection models. In each experiment a terrestrial olivine sample was ablated, under vacuum, with a 90 W continuous wave laser. The paper presents a model that better fits the outcomes of the experimental campaign, in particular in terms of mass flow rate and spot temperature.

  7. Hailey-Hailey disease improved by fractional CO2 laser.

    PubMed

    Campuzano-García, Andres Eduardo; Torres-Alvarez, Bertha; Hernández-Blanco, Diana; Castanedo-Cázares, Juan Pablo

    2015-01-01

    Hailey-Hailey disease (HHD), also known as benign familial pemphigus, is an autosomal dominant skin condition that affects the adhesion of epidermal keratinocytes. Although the initial manifestation of flaccid vesicles on erythematous or normal skin in flexure sites frequently goes unnoticed, large, macerated, exudative plaques of superficial erosions with crusting are observed at the time of diagnosis. There is no specific treatment for HHD, and most cases are symptomatically supported. However, infrared laser ablation has been somewhat helpful. We present a case successfully treated with fractional CO2 laser showing a long-term favourable outcome and no adverse effects. Thus, this modality could be an alternative to full ablation for this condition. PMID:25602185

  8. An Appetite for Fractions

    ERIC Educational Resources Information Center

    Wilkerson, Trena L.; Bryan, Tommy; Curry, Jane

    2012-01-01

    This article describes how using candy bars as models gives sixth-grade students a taste for learning to represent fractions whose denominators are factors of twelve. Using paper models of the candy bars, students explored and compared fractions. They noticed fewer different representations for one-third than for one-half. The authors conclude…

  9. Can Kindergartners Do Fractions?

    ERIC Educational Resources Information Center

    Cwikla, Julie

    2014-01-01

    Mathematics professor Julie Cwikla decided that she needed to investigate young children's understandings and see what precurricular partitioning notions young minds bring to the fraction table. Cwikla realized that only a handful of studies have examined how preschool-age and early elementary school-age students solve fraction problems…

  10. The Future of Fractions

    ERIC Educational Resources Information Center

    Usiskin, Zalman P.

    2007-01-01

    In the 1970s, the movement to the metric system (which has still not completely occurred in the United States) and the advent of hand-held calculators led some to speculate that decimal representation of numbers would render fractions obsolete. This provocative proposition stimulated Zalman Usiskin to write "The Future of Fractions" in 1979. He…

  11. (Carbon isotope fractionation inplants)

    SciTech Connect

    O'Leary, M.H.

    1990-01-01

    The objectives of this research are: To develop a theoretical and experimental framework for understanding isotope fractionations in plants; and to develop methods for using this isotope fractionation for understanding the dynamics of CO{sub 2} fixation in plants. Progress is described.

  12. Effects of material composition on the ablation performance of low density elastomeric ablators

    NASA Technical Reports Server (NTRS)

    Tompkins, S. S.; Kabana, W. P.

    1973-01-01

    The ablation performance of materials composed of various concentrations of nylon, hollow silica spheres, hollow phenolic spheres, and four elastomeric resins was determined. Both blunt-body and flat-panel specimens were used, the cold-wall heating-rate ranges being 0.11 to 0.8 MW/sq m, respectively. The corresponding surface pressure ranges for these tests were 0.017 to 0.037 atmosphere and 0.004 to 0.005 atmosphere. Some of the results show that (1) the addition of nylon significantly improved the ablation performance, but the nylon was not compatible with one resin system; (2) panel and blunt-body specimen data do not show the same effect of phenolic sphere content on ablation effectiveness; and (3) there appears to be an optimum concentration of hollow silica spheres for good ablation performance. The composition of an efficient, nonproprietary ablator for lifting body application is identified and the ablation performance of this ablator is compared with the performance of three commercially available materials.

  13. Microwave ablation versus laser ablation in occluding lateral veins in goats.

    PubMed

    Wang, Xu-hong; Wang, Xiao-ping; Su, Wen-juan; Yuan, Yuan

    2016-02-01

    Increasing number of endovenous techniques are available for the treatment of saphenous vein reflux and endovenous laser ablation (EVLA) is a frequently used method. A newly developed alternative, based on thermal therapy, is endovenous microwave ablation (EMA). This study evaluated the effect of the two procedures, in terms of coagulation and histological changes, in occluding lateral veins in goats. Twelve animals were randomized into two group, with 6 treated with EMA (EMA group), and the rest 6 with EVLA (EVLA group). Results of coagulation, including coagulation, fibrinolysis and platelet activation, were assessed at three or four different time points: before, immediately after, 24 h (and 48 h) after ablation. The diameter change, a measure of efficacy, was ultrasonographically measured before and 1 month after the ablation. Histological changes were grossly and microscopically evaluated immediately, 1 and 3 month(s) after the ablation. The length of the ablated vein and preoperative average diameter were comparable between the two groups. In both EMA and EVLA groups, several coagulation parameters, fibrinolysis and platelet activation parameters only underwent slight changes. Ultrasound imaging displayed that the diameter reduction of the veins treated by EMA was significantly larger than by EVLA, in consistent with the results of macroscopic examination. Microscopic examination revealed necrosis and thickening of the vein wall, and occlusion of the lumen within 3 months after ablation in both EMA and EVLA groups. It is concluded that EMA is a minimally invasive therapy, which appears to be safe and effective for treatment of lateral veins in goats. PMID:26838749

  14. Radiofrequency catheter ablation in pediatric patients with supraventricular arrhythmias.

    PubMed

    Rhodes, L A; Lobban, J H; Schmidt, S B

    1995-01-01

    Radiofrequency (RF) ablation of foci leading to abnormal cardiac rhythms is rapidly becoming the procedure of choice in the management of arrhythmias in adults. This report reviews our initial experience with RF ablation in the pediatric population. PMID:8533398

  15. Simulation of Double-Pulse Laser Ablation

    SciTech Connect

    Povarnitsyn, Mikhail E.; Khishchenko, Konstantin V.; Levashov, Pavel R.; Itina, Tatian E.

    2010-10-08

    We investigate the physical reasons of a strange decrease in the ablation depth observed in femtosecond double-pulse experiments with increasing delay between the pulses. Two ultrashort pulses of the same energy produce the crater which is less than that created by a single pulse. Hydrodynamic simulation shows that the ablation mechanism is suppressed when the delay between the pulses exceeds the electron-ion relaxation time. In this case, the interaction of the second laser pulse with the expanding target material leads to the formation of the second shock wave suppressing the rarefaction wave created by the first pulse. The modeling of the double-pulse ablation for different delays between pulses confirms this explanation.

  16. Deep Dive Topic: Choosing between ablators

    SciTech Connect

    Hurricane, O. A.; Thomas, C.; Olson, R.

    2015-07-14

    Recent data on implosions using identical hohlraums and very similar laser drives underscores the conundrum of making a clear choice of one ablator over another. Table I shows a comparison of Be and CH in a nominal length, gold, 575 μm-diameter, 1.6 mg/cc He gas-fill hohlraum while Table II shows a comparison of undoped HDC and CH in a +700 length, gold, 575 μm diameter, 1.6 mg/cc He gas fill hohlraum. As can be seen in the tables, the net integrated fusion performance of these ablators is the same to within error bars. In the case of the undoped HDC and CH ablators, the hot spot shapes of the implosions were nearly indistinguishable for the experiments listed in Table II.

  17. Image-Guided Spinal Ablation: A Review.

    PubMed

    Tsoumakidou, Georgia; Koch, Guillaume; Caudrelier, Jean; Garnon, Julien; Cazzato, Roberto Luigi; Edalat, Faramarz; Gangi, Afshin

    2016-09-01

    The image-guided thermal ablation procedures can be used to treat a variety of benign and malignant spinal tumours. Small size osteoid osteoma can be treated with laser or radiofrequency. Larger tumours (osteoblastoma, aneurysmal bone cyst and metastasis) can be addressed with radiofrequency or cryoablation. Results on the literature of spinal microwave ablation are scarce, and thus it should be used with caution. A distinct advantage of cryoablation is the ability to monitor the ice-ball by intermittent CT or MRI. The different thermal insulation, temperature and electrophysiological monitoring techniques should be applied. Cautious pre-procedural planning and intermittent intra-procedural monitoring of the ablation zone can help reduce neural complications. Tumour histology, patient clinical-functional status and life-expectancy should define the most efficient and least disabling treatment option. PMID:27329231

  18. Laser ablated hard coating for microtools

    DOEpatents

    McLean, II, William; Balooch, Mehdi; Siekhaus, Wigbert J.

    1998-05-05

    Wear-resistant coatings composed of laser ablated hard carbon films, are deposited by pulsed laser ablation using visible light, on instruments such as microscope tips and micro-surgical tools. Hard carbon, known as diamond-like carbon (DLC), films produced by pulsed laser ablation using visible light enhances the abrasion resistance, wear characteristics, and lifetimes of small tools or instruments, such as small, sharp silicon tips used in atomic probe microscopy without significantly affecting the sharpness or size of these devices. For example, a 10-20 nm layer of diamond-like carbon on a standard silicon atomic force microscope (AFM) tip, enables the useful operating life of the tip to be increased by at least twofold. Moreover, the low inherent friction coefficient of the DLC coating leads to higher resolution for AFM tips operating in the contact mode.

  19. Radiofrequency ablation technique eradicating palpebral margin neoplasm

    PubMed Central

    Jiang, Tian-Yu; Wang, Xing-Lin; Suo, Wei; He, Qing-Hua; Xiao, Hong-Yu

    2011-01-01

    AIM To report the study on radiofrequency ablation technique for eradication of palpebral margin neoplasm and its clinical effects. METHODS One hundred and six cases with the palpebral margin neoplasm were performed surgical removal with radiofrequency ablation technique. The 1-2 months postoperative follow-up was investigated and the lost cases were excluded from statistics. The continuing follow-up lasted about 6-16months. RESULTS One hundred cases underwent one treatment and 6 cases underwent two treatments. Six cases were missed. All the cases followed up healed well without pigmentation or scar left, nor eyelash loss or palpebral margin deformation. No case was recurrent. CONCLUSION Radiofrequency ablation has significant efficiency in eradicating the palpebral margin neoplasm. PMID:22553639

  20. Caries-selective ablation: the second threshold

    NASA Astrophysics Data System (ADS)

    Hennig, Thomas; Rechmann, Peter; Jeitner, Peter; Kaufmann, Raimund

    1993-07-01

    The aim of the study was to describe the appropriate fluence necessary for the effective removal of dental decay by ablation processes without or with at least minimal removal of healthy dentin. The experiments were conducted at two wavelengths [355 nm (frequency tripled, Q-switched Nd:YAG-laser) and 377 nm (frequency doubled, gain-switched Alexandrite-laser)] found to be close to the maximum of preferential absorption of carious dentin over healthy dentin. Optoacoustic techniques were applied to determine the ablation thresholds of healthy and carious dentin. The ablation efficiencies at characteristic fluences were determined using non-tactile microtopography. During all experiments a fiber optic delivery system was engaged.

  1. Thermal Ablation Modeling for Silicate Materials

    NASA Technical Reports Server (NTRS)

    Chen, Yih-Kanq

    2016-01-01

    A thermal ablation model for silicates is proposed. The model includes the mass losses through the balance between evaporation and condensation, and through the moving molten layer driven by surface shear force and pressure gradient. This model can be applied in ablation simulations of the meteoroid or glassy Thermal Protection Systems for spacecraft. Time-dependent axi-symmetric computations are performed by coupling the fluid dynamics code, Data-Parallel Line Relaxation program, with the material response code, Two-dimensional Implicit Thermal Ablation simulation program, to predict the mass lost rates and shape change. For model validation, the surface recession of fused amorphous quartz rod is computed, and the recession predictions reasonably agree with available data. The present parametric studies for two groups of meteoroid earth entry conditions indicate that the mass loss through moving molten layer is negligibly small for heat-flux conditions at around 1 MW/cm(exp. 2).

  2. Numerical Modeling of Ablation Heat Transfer

    NASA Technical Reports Server (NTRS)

    Ewing, Mark E.; Laker, Travis S.; Walker, David T.

    2013-01-01

    A unique numerical method has been developed for solving one-dimensional ablation heat transfer problems. This paper provides a comprehensive description of the method, along with detailed derivations of the governing equations. This methodology supports solutions for traditional ablation modeling including such effects as heat transfer, material decomposition, pyrolysis gas permeation and heat exchange, and thermochemical surface erosion. The numerical scheme utilizes a control-volume approach with a variable grid to account for surface movement. This method directly supports implementation of nontraditional models such as material swelling and mechanical erosion, extending capabilities for modeling complex ablation phenomena. Verifications of the numerical implementation are provided using analytical solutions, code comparisons, and the method of manufactured solutions. These verifications are used to demonstrate solution accuracy and proper error convergence rates. A simple demonstration of a mechanical erosion (spallation) model is also provided to illustrate the unique capabilities of the method.

  3. Advances in Imaging for Atrial Fibrillation Ablation

    PubMed Central

    D'Silva, Andrew; Wright, Matthew

    2011-01-01

    Over the last fifteen years, our understanding of the pathophysiology of atrial fibrillation (AF) has paved the way for ablation to be utilized as an effective treatment option. With the aim of gaining more detailed anatomical representation, advances have been made using various imaging modalities, both before and during the ablation procedure, in planning and execution. Options have flourished from procedural fluoroscopy, electroanatomic mapping systems, preprocedural computed tomography (CT), magnetic resonance imaging (MRI), ultrasound, and combinations of these technologies. Exciting work is underway in an effort to allow the electrophysiologist to assess scar formation in real time. One advantage would be to lessen the learning curve for what are very complex procedures. The hope of these developments is to improve the likelihood of a successful ablation procedure and to allow more patients access to this treatment. PMID:22091384

  4. Laser ablated hard coating for microtools

    DOEpatents

    McLean, W. II; Balooch, M.; Siekhaus, W.J.

    1998-05-05

    Wear-resistant coatings composed of laser ablated hard carbon films, are deposited by pulsed laser ablation using visible light, on instruments such as microscope tips and micro-surgical tools. Hard carbon, known as diamond-like carbon (DLC), films produced by pulsed laser ablation using visible light enhances the abrasion resistance, wear characteristics, and lifetimes of small tools or instruments, such as small, sharp silicon tips used in atomic probe microscopy without significantly affecting the sharpness or size of these devices. For example, a 10--20 nm layer of diamond-like carbon on a standard silicon atomic force microscope (AFM) tip, enables the useful operating life of the tip to be increased by at least twofold. Moreover, the low inherent friction coefficient of the DLC coating leads to higher resolution for AFM tips operating in the contact mode. 12 figs.

  5. Specific Impulse Definition for Ablative Laser Propulsion

    NASA Technical Reports Server (NTRS)

    Herren, Kenneth A.; Gregory, Don A.

    2004-01-01

    The term "specific impulse" is so ingrained in the field of rocket propulsion that it is unlikely that any fundamental argument would be taken seriously for its removal. It is not an ideal measure but it does give an indication of the amount of mass flow (mass loss/time), as in fuel rate, required to produce a measured thrust over some time period This investigation explores the implications of being able to accurately measure the ablation rate and how the language used to describe the specific impulse results may have to change slightly, and recasts the specific impulse as something that is not a time average. It is not currently possible to measure the ablation rate accurately in real time so it is generally just assumed that a constant amount of material will be removed for each laser pulse delivered The specific impulse dependence on the ablation rate is determined here as a correction to the classical textbook definition.

  6. Performance of Conformable Ablators in Aerothermal Environments

    NASA Technical Reports Server (NTRS)

    Thornton, J.; Fan, W.; Skokova, K.; Stackpoole, M.; Beck, R.; Chavez-Garcia, J.

    2012-01-01

    Conformable Phenolic Impregnated Carbon Ablator, a cousin of Phenolic Impregnated Carbon Ablator (PICA), was developed at NASA Ames Research Center as a lightweight thermal protection system under the Fundamental Aeronautics Program. PICA is made using a brittle carbon substrate, which has a very low strain to failure. Conformable PICA is made using a flexible carbon substrate, a felt in this case. The flexible felt significantly increases the strain to failure of the ablator. PICA is limited by its thermal mechanical properties. Future NASA missions will require heatshields that are more fracture resistant than PICA and, as a result, NASA Ames is working to improve PICAs performance by developing conformable PICA to meet these needs. Research efforts include tailoring the chemistry of conformable PICA with varying amounts of additives to enhance mechanical properties and testing them in aerothermal environments. This poster shows the performance of conformable PICA variants in arc jets tests. Some mechanical and thermal properties will also be presented.

  7. Tumor Ablation: Common Modalities and General Practices

    PubMed Central

    Knavel, Erica M.; Brace, Christopher L.

    2014-01-01

    Tumor ablation is a minimally invasive technique that is commonly used in the treatment of tumors of the liver, kidney, bone, and lung. During tumor ablation, thermal energy is used to heat or cool tissue to cytotoxic levels (less than −40°C or more than 60°C). An additional technique is being developed that targets the permeability of the cell membrane and is ostensibly nonthermal. Within the classification of tumor ablation, there are several modalities used worldwide: radiofrequency, microwave, laser, high-intensity focused ultrasound, cryoablation, and irreversible electroporation. Each technique, although similar in purpose, has specific and optimal indications. This review serves to discuss general principles and technique, reviews each modality, and discusses modality selection. PMID:24238374

  8. Excimer laser ablation of ferrite ceramics

    NASA Astrophysics Data System (ADS)

    Tam, A. C.; Leung, W. P.; Krajnovich, D.

    We study the ablation of Ni-Zn or Mn-7n ferrites by 248-nm KrF excimer laser irradiation for high-resolution patterning. A transfer lens system is used to project the image of a mask irradiated by the pulsed KrF laser onto the ferrite sample. The threshold fluente for ablation of the ferrite surface is about 0.3 J/cm2. A typical fluente of 1 J/cm2 is used to produce good-quality patterning. Scanning electron microscopy of the ablated area shows a "glassy" skin with extensive microcracks and solidified droplets being ejected that is frozen in action. This skin can be removed by ultrasonic cleaning.

  9. Ablative Rocket Deflector Testing and Computational Modeling

    NASA Technical Reports Server (NTRS)

    Allgood, Daniel C.; Lott, Jeffrey W.; Raines, Nickey

    2010-01-01

    A deflector risk mitigation program was recently conducted at the NASA Stennis Space Center. The primary objective was to develop a database that characterizes the behavior of industry-grade refractory materials subjected to rocket plume impingement conditions commonly experienced on static test stands. The program consisted of short and long duration engine tests where the supersonic exhaust flow from the engine impinged on an ablative panel. Quasi time-dependent erosion depths and patterns generated by the plume impingement were recorded for a variety of different ablative materials. The erosion behavior was found to be highly dependent on the material s composition and corresponding thermal properties. For example, in the case of the HP CAST 93Z ablative material, the erosion rate actually decreased under continued thermal heating conditions due to the formation of a low thermal conductivity "crystallization" layer. The "crystallization" layer produced near the surface of the material provided an effective insulation from the hot rocket exhaust plume. To gain further insight into the complex interaction of the plume with the ablative deflector, computational fluid dynamic modeling was performed in parallel to the ablative panel testing. The results from the current study demonstrated that locally high heating occurred due to shock reflections. These localized regions of shock-induced heat flux resulted in non-uniform erosion of the ablative panels. In turn, it was observed that the non-uniform erosion exacerbated the localized shock heating causing eventual plume separation and reversed flow for long duration tests under certain conditions. Overall, the flow simulations compared very well with the available experimental data obtained during this project.

  10. Thermal Ablation for Benign Thyroid Nodules: Radiofrequency and Laser

    PubMed Central

    Lee, Jeong Hyun; Valcavi, Roberto; Pacella, Claudio M.; Rhim, Hyunchul; Na, Dong Gyu

    2011-01-01

    Although ethanol ablation has been successfully used to treat cystic thyroid nodules, this procedure is less effective when the thyroid nodules are solid. Radiofrequency (RF) ablation, a newer procedure used to treat malignant liver tumors, has been valuable in the treatment of benign thyroid nodules regardless of the extent of the solid component. This article reviews the basic physics, techniques, applications, results, and complications of thyroid RF ablation, in comparison to laser ablation. PMID:21927553

  11. Stereotactic Body Radiotherapy and Ablative Therapies for Lung Cancer.

    PubMed

    Abbas, Ghulam; Danish, Adnan; Krasna, Mark J

    2016-07-01

    The treatment paradigm for early stage lung cancer and oligometastatic disease to the lung is rapidly changing. Ablative therapies, especially stereotactic body radiation therapy, are challenging the surgical gold standard and have the potential to be the standard for operable patients with early stage lung cancer who are high risk due to co- morbidities. The most commonly used ablative modalities include stereotactic body radiation therapy, microwave ablation, and radiofrequency ablation. PMID:27261915

  12. Ablation driven by hot electrons in shock ignition

    NASA Astrophysics Data System (ADS)

    Piriz, A. R.; Rodriguez Prieto, G.; Tahir, N. A.; Zhao, Y. T.

    2016-03-01

    An analytical model for the ablation driven by hot electrons is developed. The hot electrons are assumed to carry on the totality of the absorbed laser energy. Efficient energy coupling requires to keep the critical surface sufficiently close to the ablation front. To achieve this goal for high laser intensities a short enough laser wavelength is required. Scaling laws for the ablation pressure and the other relevant magnitudes of the ablation cloud are found in terms of the laser and target parameters.

  13. Indirect-drive ablative Richtmyer Meshkov node scaling

    NASA Astrophysics Data System (ADS)

    Landen, O. L.; Baker, K. L.; Clark, D. S.; Goncharov, V. N.; Hammel, B. A.; Ho, D. D.; Hurricane, O. A.; Lindl, J. D.; Loomis, E. N.; Masse, L.; Mauche, C.; Milovich, J. L.; Peterson, J. L.; Smalyuk, V. A.; Yi, S. A.; Velikovich, A. L.; Weber, C.

    2016-05-01

    The ablation front Rayleigh Taylor hydroinstability growth dispersion curve for indirect-drive implosions has been shown to be dependent on the Richtmyer Meshkov growth during the first shock transit phase. In this paper, a simplified treatment of the first shock ablative Richtmyer-Meshkov (ARM) growth dispersion curve is used to extract differences in ablation front perturbation growth behavior as function of foot pulse shape and ablator material for comparing the merits of various ICF design option.

  14. Subcellular analysis by laser ablation electrospray ionization mass spectrometry

    DOEpatents

    Vertes, Akos; Stolee, Jessica A; Shrestha, Bindesh

    2014-12-02

    In various embodiments, a method of laser ablation electrospray ionization mass spectrometry (LAESI-MS) may generally comprise micro-dissecting a cell comprising at least one of a cell wall and a cell membrane to expose at least one subcellular component therein, ablating the at least one subcellular component by an infrared laser pulse to form an ablation plume, intercepting the ablation plume by an electrospray plume to form ions, and detecting the ions by mass spectrometry.

  15. Testing of Advanced Conformal Ablative TPS

    NASA Technical Reports Server (NTRS)

    Gasch, Matthew; Agrawal, Parul; Beck, Robin

    2013-01-01

    In support of the CA250 project, this paper details the results of a test campaign that was conducted at the Ames Arcjet Facility, wherein several novel low density thermal protection (TPS) materials were evaluated in an entry like environment. The motivation for these tests was to investigate whether novel conformal ablative TPS materials can perform under high heat flux and shear environment as a viable alternative to rigid ablators like PICA or Avcoat for missions like MSL and beyond. A conformable TPS over a rigid aeroshell has the potential to solve a number of challenges faced by traditional rigid TPS materials (such as tiled Phenolic Impregnated Carbon Ablator (PICA) system on MSL, and honeycomb-based Avcoat on the Orion Multi Purpose Crew Vehicle (MPCV)). The compliant (high strain to failure) nature of the conformable ablative materials will allow better integration of the TPS with the underlying aeroshell structure and enable monolithic-like configuration and larger segments to be used in fabrication.A novel SPRITE1 architecture, developed by the researchers at NASA Ames was used for arcjet testing. This small probe like configuration with 450 spherecone, enabled us to test the materials in a combination of high heat flux, pressure and shear environment. The heat flux near the nose were in the range of 500-1000 W/sq cm whereas in the flank section of the test article the magnitudes were about 50 of the nose, 250-500W/sq cm range. There were two candidate conformable materials under consideration for this test series. Both test materials are low density (0.28 g/cu cm) similar to Phenolic Impregnated Carbon Ablator (PICA) or Silicone Impregnated Refractory Ceramic Ablator (SIRCA) and are comprised of: A flexible carbon substrate (Carbon felt) infiltrated with an ablative resin system: phenolic (Conformal-PICA) or silicone (Conformal-SICA). The test demonstrated a successful performance of both the conformable ablators for heat flux conditions between 50

  16. Radiofrequency Ablation Complicated by Skin Burn

    PubMed Central

    Huffman, S.D.; Huffman, N.P.; Lewandowski, Robert J.; Brown, Daniel B.

    2011-01-01

    Radiofrequency (RF) ablation has been increasingly utilized as a minimally invasive treatment for primary and metastatic liver tumors, as well as tumors in the kidneys, bones, and adrenal glands. The development of high-current RF ablation has subsequently led to an increased risk of thermal skin injuries at the grounding pad site. The incidence of skin burns in recent studies ranges from 0.1–3.2% for severe skin burns (second-/third-degree), and from 5–33% for first-degree burns.1–3 PMID:22654258

  17. High throughput solar cell ablation system

    SciTech Connect

    Harley, Gabriel; Pass, Thomas; Cousins, Peter John; Viatella, John

    2014-10-14

    A solar cell is formed using a solar cell ablation system. The ablation system includes a single laser source and several laser scanners. The laser scanners include a master laser scanner, with the rest of the laser scanners being slaved to the master laser scanner. A laser beam from the laser source is split into several laser beams, with the laser beams being scanned onto corresponding wafers using the laser scanners in accordance with one or more patterns. The laser beams may be scanned on the wafers using the same or different power levels of the laser source.

  18. High throughput solar cell ablation system

    SciTech Connect

    Harley, Gabriel; Pass, Thomas; Cousins, Peter John; Viatella, John

    2012-09-11

    A solar cell is formed using a solar cell ablation system. The ablation system includes a single laser source and several laser scanners. The laser scanners include a master laser scanner, with the rest of the laser scanners being slaved to the master laser scanner. A laser beam from the laser source is split into several laser beams, with the laser beams being scanned onto corresponding wafers using the laser scanners in accordance with one or more patterns. The laser beams may be scanned on the wafers using the same or different power levels of the laser source.

  19. General Model for Multicomponent Ablation Thermochemistry

    NASA Technical Reports Server (NTRS)

    Milos, Frank S.; Marschall, Jochen; Rasky, Daniel J. (Technical Monitor)

    1994-01-01

    A previous paper (AIAA 94-2042) presented equations and numerical procedures for modeling the thermochemical ablation and pyrolysis of thermal protection materials which contain multiple surface species. This work describes modifications and enhancements to the Multicomponent Ablation Thermochemistry (MAT) theory and code for application to the general case which includes surface area constraints, rate limited surface reactions, and non-thermochemical mass loss (failure). Detailed results and comparisons with data are presented for the Shuttle Orbiter reinforced carbon-carbon oxidation protection system which contains a mixture of sodium silicate (Na2SiO3), silica (SiO2), silicon carbide (SiC), and carbon (C).

  20. Effects of Laser Wavelength on Ablator Testing

    NASA Technical Reports Server (NTRS)

    White, Susan M.

    2014-01-01

    Wavelength-dependent or spectral radiation effects are potentially significant for thermal protection materials. NASA atmospheric entry simulations include trajectories with significant levels of shock layer radiation which is concentrated in narrow spectral lines. Tests using two different high powered lasers, the 10.6 micron LHMEL I CO2 laser and the near-infrared 1.07 micron fiber laser, on low density ablative thermal protection materials offer a unique opportunity to evaluate spectral effects. Test results indicated that the laser wavelength can impact the thermal response of an ablative material, in terms of bond-line temperatures, penetration times, mass losses, and char layer thicknesses.

  1. Difficulties with Ablation for Arrhythmias in Children

    PubMed Central

    Asirvatham, Samuel J

    2008-01-01

    Radiofrequency ablation procedures in children present unique challenges for the electrophysiologist. At times, obtaining vascular access to reach the heart is a problem. If this first step is accomplished, the small size of the child's heart, arrhythmias relatively unique to the pediatric population, and the presence of congenital heart disease add to the complexity. In this manuscript, a review of commonly encountered problems and suggested solutions based on practice are presented. Precise mapping of the arrhythmogenic substrate, techniques to access excluded portions of the atrium from prior surgery, and the basis for electrophysiology maneuvers important in pediatric ablation are highlighted. PMID:18478062

  2. Experimental measurement of ablation effects in plasma armature railguns

    SciTech Connect

    Parker, J.V.; Parsons, W.M.

    1986-01-01

    Experimental evidence supporting the importance of ablation in plasma armature railguns is presented. Experiments conducted using the HYVAX and MIDI-2 railguns are described. Several indirect effects of ablation are identified from the experimental results. An improved ablation model of plasma armature dynamics is proposed which incorporates the restrike process.

  3. Sensors measure surface ablation rate of reentry vehicle heat shield

    NASA Technical Reports Server (NTRS)

    Russel, J. M., III

    1966-01-01

    Sensors measure surface erosion rate of ablating material in reentry vehicle heat shield. Each sensor, which is placed at precise depths in the heat shield is activated when the ablator surface erodes to the location of a sensing point. Sensor depth and activation time determine ablator surface erosion rate.

  4. Experimental measurement of ablation effects in plasma armature railguns

    NASA Astrophysics Data System (ADS)

    Parker, J. V.; Parsons, W. M.

    Experimental evidence supporting the importance of ablation in plasma armature railguns is presented. Experiments conducted using the HYVAX and MIDI-2 railguns are described. Several indirect effects of ablation are identified from the experimental results. An improved ablation model of plasma armature dynamics is proposed which incorporates the restrike process.

  5. Ablation techniques for primary and metastatic liver tumors.

    PubMed

    Ryan, Michael J; Willatt, Jonathon; Majdalany, Bill S; Kielar, Ania Z; Chong, Suzanne; Ruma, Julie A; Pandya, Amit

    2016-01-28

    Ablative treatment methods have emerged as safe and effective therapies for patients with primary and secondary liver tumors who are not surgical candidates at the time of diagnosis. This article reviews the current literature and describes the techniques, complications and results for radiofrequency ablation, microwave ablation, cryoablation, and irreversible electroporation. PMID:26839642

  6. Ablation techniques for primary and metastatic liver tumors

    PubMed Central

    Ryan, Michael J; Willatt, Jonathon; Majdalany, Bill S; Kielar, Ania Z; Chong, Suzanne; Ruma, Julie A; Pandya, Amit

    2016-01-01

    Ablative treatment methods have emerged as safe and effective therapies for patients with primary and secondary liver tumors who are not surgical candidates at the time of diagnosis. This article reviews the current literature and describes the techniques, complications and results for radiofrequency ablation, microwave ablation, cryoablation, and irreversible electroporation. PMID:26839642

  7. Time-resolved studies of particle effects in laser ablation inductively coupled plasma-mass spectrometry

    SciTech Connect

    Perdian, D.; Bajic, S.; Baldwin, D.; Houk, R.

    2007-11-13

    Transient signal responses for ablated samples as a function of particle size and laser parameters are characterized. Data are acquired with time resolution of 5 or 6 ms per data point. Large positive spikes in signal are observed and increase in both amplitude and frequency with increasing particle size. Particle sizes are selected using a differential mobility analyzer. Spikes in the signal also increase with decreasing laser rastering rates. A comparison of lasers with pulse widths of 370 fs and 5 ns shows that shortening the pulse width significantly reduces the frequency and amplitude of positive spikes in signal. These large positive spikes are attributed to the vaporization, atomization, and ionization of individual large intact particles, which are considered to be a major cause of fractionation in laser ablation ICP-MS.

  8. Millimeter-wave broadband antireflection coatings using laser ablation of subwavelength structures.

    PubMed

    Matsumura, Tomotake; Young, Karl; Wen, Qi; Hanany, Shaul; Ishino, Hirokazu; Inoue, Yuki; Hazumi, Masashi; Koch, Jürgen; Suttman, Oliver; Schütz, Viktor

    2016-05-01

    We report on the first use of laser ablation to make submillimeter, broadband, antireflection coatings (ARCs) based on subwavelength structures (SWSs) on alumina and sapphire. We used a 515 nm laser to produce pyramid-shaped structures with a pitch of about 320 μm and a total height of near 800 μm. Transmission measurements between 70 and 140 GHz are in agreement with simulations using electromagnetic propagation software. The simulations indicate that SWS-ARCs with the fabricated shape should have a fractional bandwidth response of Δν/νcenter=0.55 centered on 235 GHz for which reflections are below 3%. Extension of the bandwidth to both lower and higher frequencies, between a few tens of gigahertz and a few terahertz, should be straightforward with appropriate adjustment of laser ablation parameters. PMID:27140362

  9. Absorption of a single 500 fs laser pulse at the surface of fused silica: Energy balance and ablation efficiency

    SciTech Connect

    Varkentina, N.; Sanner, N.; Lebugle, M.; Sentis, M.; Utéza, O.

    2013-11-07

    Ablation of fused silica by a single femtosecond laser pulse of 500 fs pulse duration is investigated from the perspective of efficiency of incident photons to remove matter. We measure the reflected and transmitted fractions of the incident pulse energy as a function of fluence, allowing us to recover the evolution of absorption at the material surface. At the ablation threshold fluence, 25% of incident energy is absorbed. At high fluences, this ratio saturates around 70% due to the appearance of a self-triggered plasma mirror (or shielding) effect. By using the energy balance retrieved experimentally and measurements of the ablated volume, we show that the amount of absorbed energy is far above the bonding energy of fused silica at rest and also above the energy barrier to ablate the material under non-equilibrium thermodynamic conditions. Our results emphasize the crucial role of transient plasma properties during the laser pulse and suggest that the major part of the absorbed energy has been used to heat the plasma formed at the surface of the material. A fluence range yielding an efficient and high quality ablation is also defined, which makes the results relevant for femtosecond micromachining processes.

  10. Pathophysiologic basis of autonomic ganglionated plexus ablation in patients with atrial fibrillation.

    PubMed

    Nakagawa, Hiroshi; Scherlag, Benjamin J; Patterson, Eugene; Ikeda, Atsuhsi; Lockwood, Deborah; Jackman, Warren M

    2009-12-01

    The intrinsic cardiac autonomic nervous system (ganglionated plexuses [GP]) plays a significant role in the initiation and maintenance of atrial fibrillation (AF) in both experimental models and AF patients. Left atrial GP, located in epicardial fat pads and the ligament of Marshall, contain afferent neurons from the atrial myocardium and the central autonomic nervous system, efferent neurons (cholinergic and adrenergic neurons), and interconnecting neurons, which allow communication between GP. Stimulation of the GP produces both parasympathetic stimulation (markedly shortens action potential duration) and sympathetic stimulation (increases calcium transient) in the pulmonary vein (PV) myocardium and atrial myocardium. In a canine model, GP stimulation resulted in early afterdepolarizations, and calcium transient triggered firing in the adjacent PV and initiated AF. Fractionated atrial potentials (FAP) were consistently located in the left atrium close to the stimulated GP. Ablation of the stimulated GP eliminated the FAP surrounding the GP. In patients with paroxysmal AF, epicardial and endocardial high-frequency stimulation produced a positive vagal response (transient AV block during AF and hypotension), allowing the identification and localization of five major left atrial GP (superior left GP, inferior left GP, Marshall tract GP, anterior right GP, inferior right GP). High-density electroanatomic maps of the left atrium and PVs obtained during AF showed the FAP are located in four main left atrial areas (left atrial appendage ridge FAP area, superior-left FAP area, inferoposterior FAP area, anterior-right FAP area). All five GP are located within one of the four FAP areas. In 63 patients with paroxysmal AF, GP ablation alone (before PV antrum isolation) significantly decreased the occurrence of PV firing (47/63 patients before ablation vs 9/63 patients after ablation, P <.01). GP ablation also decreased the inducibility of sustained AF (43/63 patients vs 23

  11. Optimization of laser ablation and signal enhancement for nuclear material detection

    NASA Astrophysics Data System (ADS)

    LaHaye, Nicole L.

    The purpose of the study was to investigate the role of different laser parameters on laser ablation properties, specifically in terms of performance in laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). Many laser parameters affect laser ablation performance, including laser wavelength and pulse duration, as presented here. It was previously thought that wavelength plays no role in ultrafast laser ablation; however, it was found that shorter wavelength yields lower detection limits and ablation threshold. Our results also demonstrate that in the laser pulse duration range of 40 fs to 1 ps, negligible differences occur in signal intensity, elemental ratios, and detection limits. U/Pb and U/Th ratios, which were examined to ensure limited fractionation, give comparable results at all pulse widths investigated. A parametric study of plasma hydrodynamics will also be presented. An elemental detection method combining laser induced breakdown spectroscopy (LIBS) and LA-ICP-MS is developed, with plasma density and temperature actively monitored to investigate how plasma conditions affect ICP-MS results. The combination of these two methods will help to mitigate the disadvantages of using each technique individually. Depth and spatial analysis of thin films was performed using femtosecond LA-ICP-MS to study the stoichiometric distribution of the films. The thin film-substrate interface was probed, revealing intermixing between the two layers. Lastly, the persistence of uranium emission in laser-produced plasmas (LPP) was investigated under various Ar ambient environments. Plasma collisional effects and confinement play a very important role in emission intensity and persistence, yielding important results for future LIBS and laser absorption spectroscopy (LAS) research. Lastly, suggestions for future work are made, which include extension of the LIBS and LA-ICP-MS systems to other samples like oxide thin films and spatial and depth profiling of known

  12. Ablate and pace revisited: long term survival and predictors of permanent atrial fibrillation

    PubMed Central

    Queiroga, A; Marshall, H J; Clune, M; Gammage, M D

    2003-01-01

    Objective: To assess long term mortality and identify factors associated with the development of permanent atrial fibrillation after atrioventricular (AV) node ablation for drug refractory paroxysmal atrial fibrillation. Design: Retrospective cohort study. Setting: UK tertiary centre teaching hospital. Patients: Patients admitted to the University Hospital Birmingham between January 1995 and December 2000. Interventions: AV node ablation and dual chamber mode switching pacing. Main outcome measures: Long term mortality and predictors of permanent atrial fibrillation, assessed through Kaplan-Meier curves and logistic regression. Results: 114 patients (1995–2000) were included: age (mean (SD)), 65 (9) years; 55 (48%) male; left atrial diameter 4 (1) cm; left ventricular end diastolic diameter 5 (1) cm; ejection fraction 54 (17)%. Indications for AV node ablation were paroxysmal atrial fibrillation in 95 (83%) and paroxysmal atrial fibrillation/flutter in 19 (17%). The survival curve showed a low overall mortality after 72 months (10.5%). Fifty two per cent of patients progressed to permanent atrial fibrillation within 72 months. There was no difference in progression to permanency between paroxysmal atrial fibrillation and paroxysmal atrial fibrillation/flutter (log rank 0.06, p = 0.8). Logistic regression did not show any association between the variables collected and the development of permanent atrial fibrillation, although age over 80 years showed a trend (p = 0.07). Conclusions: Ablate and pace is associated with a low overall mortality. No predictors of permanent atrial fibrillation were identified, but 48% of patients were still in sinus rhythm at 72 months. These results support the use of dual chamber pacing for paroxysmal atrial fibrillation patients after ablate and pace. PMID:12923021

  13. Fractional calculus in bioengineering.

    PubMed

    Magin, Richard L

    2004-01-01

    Fractional calculus (integral and differential operations of noninteger order) is not often used to model biological systems. Although the basic mathematical ideas were developed long ago by the mathematicians Leibniz (1695), Liouville (1834), Riemann (1892), and others and brought to the attention of the engineering world by Oliver Heaviside in the 1890s, it was not until 1974 that the first book on the topic was published by Oldham and Spanier. Recent monographs and symposia proceedings have highlighted the application of fractional calculus in physics, continuum mechanics, signal processing, and electromagnetics, but with few examples of applications in bioengineering. This is surprising because the methods of fractional calculus, when defined as a Laplace or Fourier convolution product, are suitable for solving many problems in biomedical research. For example, early studies by Cole (1933) and Hodgkin (1946) of the electrical properties of nerve cell membranes and the propagation of electrical signals are well characterized by differential equations of fractional order. The solution involves a generalization of the exponential function to the Mittag-Leffler function, which provides a better fit to the observed cell membrane data. A parallel application of fractional derivatives to viscoelastic materials establishes, in a natural way, hereditary integrals and the power law (Nutting/Scott Blair) stress-strain relationship for modeling biomaterials. In this review, I will introduce the idea of fractional operations by following the original approach of Heaviside, demonstrate the basic operations of fractional calculus on well-behaved functions (step, ramp, pulse, sinusoid) of engineering interest, and give specific examples from electrochemistry, physics, bioengineering, and biophysics. The fractional derivative accurately describes natural phenomena that occur in such common engineering problems as heat transfer, electrode/electrolyte behavior, and sub

  14. Multiple daily fractionation schedules

    SciTech Connect

    Peschel, R.E.; Fischer, J.J.

    1982-10-01

    Although conventional fractionation schedules have been satisfactory for the treatment of some tumors, there is reason to believe that the results of radiation therapy could be improved in some cases by appropriate alterations in treatment schedules. The pharmacological characteristics of some of the electron affinic radiation sensitizers have provided added incentive to investigate newer fractionation schemes, particularly ones which deliver the majority of the radiation dose in short periods of time. This editorial discusses three papers describing preliminary clinical studies using multi-daily fractionated (MDF) radiation therapy. Two of these studies also make use of the radiation sensitizer misonidazole. (KRM)

  15. [The incidence of ventricular arrhythmia following direct current ablation, high-frequency current ablation and laser photo-ablation].

    PubMed

    Hindricks, G; Haverkamp, W; Dute, U; Gülker, H

    1988-11-01

    Incidence and severity of ventricular arrhythmias (VA) following transvenous catheter ablation have so far not been fully elucidated. In the present study we evaluated the comparative incidence of postablation ventricular arrhythmias following high voltage-direct current electrical ablation (DCA), radiofrequency-ablation (RFA), and laser-photoablation (LPA). Experiments were performed on a total of 26 anesthetized mongrel dogs (BW: 20-30 kg). DCA (n = 14; 150-200 J) and RFA (n = 7; 38.5-72.5 J) were performed unipolarly via a 6F USCI catheter, LPA (n = 5; 40-80 J) was delivered through a quarz core fiber (diameter 0.4 mm) housed within a special designed catheter. Energies were delivered to various sites of free wall and apical endocardium of the left ventricle. Immediately after DCA fast runs of ventricular tachycardia (VT) developed in 13 out of 14 dogs degenerating into ventricular fibrillation in two animals. Mean cycle length of induced VT was 298 +/- 86 ms. Persistent VA, morphologically mainly characterized by an accelerated idioventricular rhythm interrupted by runs of ventricular salvoes, occurred in 12 animals (mean rate: 78 +/- 13 VPB/min 3 h after ablation). During VT early endocardial activations were recorded from the ablation site. No significant correlation between total applied energy (150-550 J) and incidence of arrhythmogenic effects was observed. RFA and LPA induced ventricular salvoes and runs of non-sustained ventricular tachycardia, in one animal ventricular fibrillation occurred during RFA; however, no persistent arrhythmic activity developed after RFA and LPA, respectively.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3213137

  16. Therapeutic effects of ablative radiation on local tumor require CD8+ T cells: changing strategies for cancer treatment

    PubMed Central

    Lee, Youjin; Auh, Sogyong L.; Wang, Yugang; Burnette, Byron; Wang, Yang; Meng, Yuru; Beckett, Michael; Sharma, Rohit; Chin, Robert; Tu, Tony

    2009-01-01

    Patients with locally advanced cancer or distant metastasis frequently receive prolonged treatment with chemotherapy and/or fractionated radiotherapy (RT). Despite the initial clinical response, treatment resistance frequently develops and cure in these patients is uncommon. Developments in RT technology allow for the use of high-dose (or ablative) RT to target local tumors, with limited damage to the surrounding normal tissue. We report that reduction of tumor burden after ablative RT depends largely on T-cell responses. Ablative RT dramatically increases T-cell priming in draining lymphoid tissues, leading to reduction/eradication of the primary tumor or distant metastasis in a CD8+ T cell–dependent fashion. We further demonstrate that ablative RT-initiated immune responses and tumor reduction are abrogated by conventional fractionated RT or adjuvant chemotherapy but greatly amplified by local immunotherapy. Our study challenges the rationale for current RT/chemotherapy strategies and highlights the importance of immune activation in preventing tumor relapse. Our findings emphasize the need for new strategies that not only reduce tumor burden but also enhance the role of antitumor immunity. PMID:19349616

  17. FCC main fractionator revamps

    SciTech Connect

    Golden, S.W.; Martin, G.R.; Sloley, A.W. )

    1993-03-01

    Structured packing use in fluid catalytic cracker (FCC) main fractionators significantly impacts unit pressure profile. Unit pressure balance links the FCC main fractionator, reactor, regenerator, air compressor and wet gas compressor. Unit pressure balance should be viewed as a design variable when evaluating FCC unit revamps. Depending upon limitations of the particular FCC unit, capacity increases of 12.5% to 22.5% have been achieved without modifications to major rotating equipment, by revamping FCC main fractionators with structured packing. An examination of three FCC main fractionator revamps show improvements to pressure profiles and unit capacity. The three revamps described included a wet gas compressor volume limit; an air blower limitation; and a wet gas compressor motor limitation.

  18. Multi-modal albedo distributions in the ablation area of the southwestern Greenland Ice Sheet

    NASA Astrophysics Data System (ADS)

    Moustafa, S. E.; Rennermalm, A. K.; Smith, L. C.; Miller, M. A.; Mioduszewski, J. R.; Koenig, L. S.; Hom, M. G.; Shuman, C. A.

    2015-05-01

    Surface albedo is a key variable controlling solar radiation absorbed at the Greenland Ice Sheet (GrIS) surface and, thus, meltwater production. Recent decline in surface albedo over the GrIS has been linked to enhanced snow grain metamorphic rates, earlier snowmelt, and amplified melt-albedo feedback from atmospheric warming. However, the importance of distinct surface types on ablation area albedo and meltwater production is still relatively unknown. In this study, we analyze albedo and ablation rates using in situ and remotely sensed data. Observations include (1) a new high-quality in situ spectral albedo data set collected with an Analytical Spectral Devices Inc. spectroradiometer measuring at 325-1075 nm along a 1.25 km transect during 3 days in June 2013; (2) broadband albedo at two automatic weather stations; and (3) daily MODerate Resolution Imaging Spectroradiometer (MODIS) albedo (MOD10A1) between 31 May and 30 August 2012 and 2013. We find that seasonal ablation area albedos in 2013 have a bimodal distribution, with snow and ice facies characterizing the two peaks. Our results show that a shift from a distribution dominated by high to low albedos corresponds to an observed melt rate increase of 51.5% (between 10-14 July and 20-24 July 2013). In contrast, melt rate variability caused by albedo changes before and after this shift was much lower and varied between ~10 and 30% in the melting season. Ablation area albedos in 2012 exhibited a more complex multimodal distribution, reflecting a transition from light to dark-dominated surface, as well as sensitivity to the so called "dark-band" region in southwest Greenland. In addition to a darkening surface from ice crystal growth, our findings demonstrate that seasonal changes in GrIS ablation area albedos are controlled by changes in the fractional coverage of snow, bare ice, and impurity-rich surface types. Thus, seasonal variability in ablation area albedos appears to be regulated primarily as a function

  19. A study of particle generation during laser ablation withapplications

    SciTech Connect

    Liu, Chunyi

    2005-08-12

    A study has been made of the generation of particles during laser ablation and has included size distribution measurements and observation of the formation processes. The particle size distribution with respect to different laser parameters was obtained in-line using a differential mobility analyzer (DMA) and a particle counter. The experimental results show that the particle size varies with laser energy, laser pulsewidth, ambient gas flow rate and sample properties. The results serve as a basis for controlling the size of nanoparticles generated by laser ablation. Laser shadowgraph imaging was used to study mass ejection processes and mechanisms. At higher laser irradiance, some particles were ejected in the liquid and even in the solid phase. Time-resolved images show the propagation of the shockwaves: external shockwaves propagate outward and decelerate, and internal shockwaves reflect back and forth between the gas contact surface and the sample surface. The internal shockwave is proposed to cause the ejection of liquid particles when the internal shockwave strikes the liquid molten layer. A simulation based on vapor plume expansion was carried out and provides satisfactory agreement with experimental results. Different material properties result in different particle ejection behavior:particle ejection for most materials including metals result in a conically shaped envelope for the ejected material while ejection for silicon resembles a liquid jet. The difference in density change when the materials melt was proposed to be an important factor in the different ejection behavior. The characteristics of particles generated by laser ablation have a strong influence on the chemical analysis of the irradiated sample. Large particles are more difficult to completely vaporize and ionize, and induced preferential vaporization causes fractionation (i.e. a detected chemical composition that differs from the sample material). Large particles also result in spikes in

  20. UV laser ablation patterns in intraocular lenses

    NASA Astrophysics Data System (ADS)

    Lagiou, D. P.; Evangelatos, Ch.; Apostolopoulos, A.; Spyratou, E.; Bacharis, C.; Makropoulou, M.; Serafetinides, A. A.

    2013-03-01

    The aim of this work is to investigate the effect of UV solid state laser radiation on intraocular lens (IOL) polymer surfaces as an alternative method to conventional surface shaping techniques for IOLs customization. Laser ablation experiments were performed on PMMA plates and commercially available hydrophobic and hydrophilic acrylic IOLs with the 5th harmonic of a Q-switched Nd:YAG laser (λ=213 nm). Circular arrays of holes were drilled on the polymer surface, covering the centre and the peripheries of the IOL. The morphology of the ablated IOL surface was examined with a conventional optical microscope (Leitz GMBH Wetzlar) and with a scanning electron microscope (SEM, Fei - Innova Nanoscope) at various laser parameters. Quantitative measurements of ablation rates were performed with a contact profilometer (Dektak-150), in which a mechanical stylus scanned across the surface of gold-coated IOLs (after SEM imaging) to measure variationsF in surface height. Laser interaction with IOLs depends on optical and mechanical material properties, in addition to laser radiation parameters. The exact ablation mechanism is discussed. Some polymer materials, depending on their properties, are more susceptible to the photothermal mechanism than the photochemical one or vice versa. In summary, every IOL polymer exhibits specific attributes in its interaction with the 5th harmonic of Nd:YAG laser.