A theoretical investigation of human skin thermal response to near-infrared laser irradiation

Near-infrared wavelengths are absorbed less by epidermal melanin mainly located at the basal layer of epidermis (dermo-epidermal junction), and penetrate deeper into human skin dermis and blood than visible wavelengths. Therefore, laser irradiation using near-infrared wavelength may improve the therapeutic outcome of cutaneous hyper-vascular malformations in moderately to heavily pigmented skin patients and those with large-sized blood vessels or blood vessels extending deeply into the skin. A mathematical model composed of a Monte Carlo algorithm to estimate the distribution of absorbed light followed by numerical solution of a bio-heat diffusion equation was utilized to investigate the thermal response of human skin to near-infrared laser irradiation, and compared it with that to visible laser irradiation. Additionally, the effect of skin surface cooling on epidermal protection was theoretically investigated. Simulation results indicated that 940 nm wavelength is superior to 810 and 1064 nm in terms of the ratio of light absorption by targeted blood vessel to the absorption by the basal layer of epidermis, and is more efficient than 595 nm wavelength for the treatment of patients with large-sized blood vessels and moderately to heavily pigmented skin. Dermal blood content has a considerable effect on the laser-induced peak temperature at the basal layer of epidermis, while the effect of blood vessel size is minimum

A theoretical investigation of human skin thermal response to near-infrared laser irradiation

Near-infrared wavelengths are absorbed less by epidermal melanin mainly located at the basal layer of epidermis (dermo-epidermal junction), and penetrate deeper into human skin dermis and blood than visible wavelengths. Therefore, laser irradiation using near-infrared wavelength may improve the therapeutic outcome of cutaneous hyper-vascular malformations in moderately to heavily pigmented skin patients and those with large-sized blood vessels or blood vessels extending deeply into the skin. A mathematical model composed of a Monte Carlo algorithm to estimate the distribution of absorbed light followed by numerical solution of a bio-heat diffusion equation was utilized to investigate the thermal response of human skin to near-infrared laser irradiation, and compared it with that to visible laser irradiation. Additionally, the effect of skin surface cooling on epidermal protection was theoretically investigated. Simulation results indicated that 940 nm wavelength is superior to 810 and 1064 nm in terms of the ratio of light absorption by targeted blood vessel to the absorption by the basal layer of epidermis, and is more efficient than 595 nm wavelength for the treatment of patients with large-sized blood vessels and moderately to heavily pigmented skin. Dermal blood content has a considerable effect on the laser-induced peak temperature at the basal layer of epidermis, while the effect of blood vessel size is minimum

Asiakaspalaute OP-bonusjärjestelmästä Ruukin OP:ssa

Tämän opinnäytetyön tarkoituksena oli selvittää asiakkaiden yleistä asiakastyytyväisyyttä ja mielipidettä sekä saada parannusehdotuksia. Teoreettisessa osuudessa käydään läpi OP-Pohjola-ryhmän yritysrakennetta, historiaa, tunnuslukuja, omistajajäsenyyttä, etuasiakkuutta ja keskittäjäasiakkuutta. Asiakassuhdemarkkinoinnilla on tärkeä rooli pankkien toiminnassa, joten myös sitä on käsitelty työssä. Laadullisen tutkimuksen osiossa tarkastellaan puhelimella tehtyä asiakaskyselyä, johon vastasi 30 omistajajäsentä. Kysymyksillä pyrittiin saamaan selville omistajajäsenten tiedot OP-bonusjärjestelmästä, tiedonsaannista sekä annettiin mahdollisuus antaa palautetta. Tutkimuksesta saadut tulokset osoittivat, että omistajajäsenet kokevat OP-bonusjärjestelmän tutuksi, mutta OP-bonusten kertymis- ja käyttökohteista ei tunnisteta kuin muutama. Avoin palaute OP-bonusjärjestelmästä oli pääsääntöisesti positiivista.The purpose of this thesis was to analyze general customer satisfaction and opinions, and to get proposals for improvements. The theoretical part of the study deals with the OP-Pohjola Group company structure, history, key ratios and owner membership, benefit customership and focus customership. Customer relationship marketing has an important role in the operation of banks so it is also discussed in the study. The part of the qualitative research examines the customer surveys carried out by phone and replied by 30 owner members.The goal of the survey questions was to find out what owner members know about the OP-bonussystem, how and where they get information. It was also possible for them to givefeedback. The study results showed that the owner members regard the OP-bonussystem as familiar. However, only few of the accumulating and use targets of OP bonuses were identified. The open feedback on the OP-bonussystem was positive as a main rule

Optimization of cryogen spray cooling: Increasing epidermal protection during cutaneous laser procedures

Cryogen spray cooling (CSC) is an effective method to minimize epidermal damage during laser treatment of various cutaneous anomalies such as port wine stains (PWS). We examined the mechanism of heat removal by CSC from skin, and heat removal was compared for CSC and contact cooling, another precooling method for cutaneous laser therapy. Next, we examined the heat removal ability of various cryogen delivery devices using a skin phantom and an inverse heat conduction algorithm. Third, the droplet characteristics were evaluated and correlated with heat removal in the skin phantom. An ex vivo study was used to confirm the results of the phantom work. Lastly, a comparative study of the droplet characteristics used to increase heat removal was performed on in vivo human skin to verify results from previous studies. Results demonstrated that heat removal is limited in skin by its low thermal diffusivity and heat removal by evaporative cooling was negligible on skin using CSC. Next, it was determined that different cryogen delivery devices remove various amounts of heat from the skin phantom. The cause of the differing rates of heat removal was determined to be by three main factors: the initial temperature differential between the impinging droplets and substrate, velocity of the droplets, and droplet diameter. The Weber number, which is proportional to the velocity2·diameter, showed a correlation to heat removal in the skin phantom. Using an equal temperature differential, it was confirmed that an increased Weber number provided greater epidermal protection in ex vivo human skin in response to laser irradiation. Lastly, an in vivo study of human skin also demonstrated that an increased Weber number spray was better able to reduce nonspecific thermal damage, especially with darker skin types, in response to 595 nm pulsed laser irradiation. Gross purpura after irradiation was correlated to vascular damage histologically and to apoptosis, giving the clinician a visual indication of the vascular damage occurring. This study confirmed that although the low thermal diffusivity of skin is a limiting factor in heat removal, altering the droplet characteristics can increase heat removal and provide increased epidermal protection

Comparison of human skin opto-thermal response to near-infrared and visible laser irradiations: a theoretical investigation

Near-infrared wavelengths are absorbed less by epidermal melanin, and penetrate deeper into human skin dermis and blood than visible wavelengths. Therefore, laser irradiation using near-infrared wavelengths may improve the therapeutic outcome of cutaneous hyper-vascular malformations in moderately to heavily pigmented skin patients and those with large-sized blood vessels or blood vessels extending deeply into the skin. A mathematical model composed of a Monte Carlo algorithm to estimate the distribution of absorbed light, numerical solution of a bio-heat diffusion equation to calculate the transient temperature distribution, and a damage integral based on an empirical Arrhenius relationship to quantify the tissue damage was utilized to investigate the opto-thermal response of human skin to near-infrared and visible laser irradiations in conjunction with cryogen spray cooling. In addition, the thermal effects of a single continuous laser pulse and micropulse-composed laser pulse profiles were compared. Simulation results indicated that a 940 nm wavelength induces improved therapeutic outcome compared with a 585 and 595 nm wavelengths for the treatment of patients with large-sized blood vessels and moderately to heavily pigmented skin. On the other hand, a 585 nm wavelength shows the best efficacy in treating small-sized blood vessels, as characterized by the largest laser-induced blood vessel damage depth compared with 595 and 940 nm wavelengths. Dermal blood content has a considerable effect on the threshold incident dosage for epidermal damage, while the effect of blood vessel size is minimal. For the same macropulse duration and incident dosage, a micropulse-composed pulse profile results in higher peak temperature at the basal layer of skin epidermis than an ideal single continuous pulse profile

Comparison of human skin opto-thermal response to near-infrared and visible laser irradiations: a theoretical investigation

Near-infrared wavelengths are absorbed less by epidermal melanin, and penetrate deeper into human skin dermis and blood than visible wavelengths. Therefore, laser irradiation using near-infrared wavelengths may improve the therapeutic outcome of cutaneous hyper-vascular malformations in moderately to heavily pigmented skin patients and those with large-sized blood vessels or blood vessels extending deeply into the skin. A mathematical model composed of a Monte Carlo algorithm to estimate the distribution of absorbed light, numerical solution of a bio-heat diffusion equation to calculate the transient temperature distribution, and a damage integral based on an empirical Arrhenius relationship to quantify the tissue damage was utilized to investigate the opto-thermal response of human skin to near-infrared and visible laser irradiations in conjunction with cryogen spray cooling. In addition, the thermal effects of a single continuous laser pulse and micropulse-composed laser pulse profiles were compared. Simulation results indicated that a 940 nm wavelength induces improved therapeutic outcome compared with a 585 and 595 nm wavelengths for the treatment of patients with large-sized blood vessels and moderately to heavily pigmented skin. On the other hand, a 585 nm wavelength shows the best efficacy in treating small-sized blood vessels, as characterized by the largest laser-induced blood vessel damage depth compared with 595 and 940 nm wavelengths. Dermal blood content has a considerable effect on the threshold incident dosage for epidermal damage, while the effect of blood vessel size is minimal. For the same macropulse duration and incident dosage, a micropulse-composed pulse profile results in higher peak temperature at the basal layer of skin epidermis than an ideal single continuous pulse profile