Kenneth R. Diller

University of Texas at Austin, Austin, Texas, United States

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Publications (199)324.15 Total impact

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    ABSTRACT: Relatively little is understood about the practice of teaching for adaptability. Our prior research demonstrates that challenge-based instruction (CBI) can foster Adaptive Expertise (AE). AE is a combination of 1) traditional routine expertise as defined by content knowledge and its correct application and 2) the skills and habits to use that knowledge in new ways on novel problems. The experiments reported in this paper investigate the hypotheses that 1) both the nature of the learning environment (adaptive or routine) and the level of expertise of the learner (adaptive or routine) are important for understanding the development of innovation and efficiency, and 2) innovation and efficiency co-develop in the CBI environment. In Experiment 1, we examined students' exam performance, coding for both innovation and efficiency, across a complete implementation of the CBI biotransport course. We assessed students' level of innovation and efficiency on routine and adaptive problems at four time points at the grain size of exam questions. In Experiment 2, we interviewed eight students three times over the course of their biotransport class. Students solved the same heat transfer problem on each interview, talking aloud as they solved the problem. This design enabled the use of text analysis and clustering learning analytics methods to examine how students' use of innovation and efficiency changed over the course of the interviews in small time segments. Both experiments demonstrated gains in innovation and efficiency, and appropriate use of them given the context of the task. Experiment 2 additionally demonstrated the co-developing nature of the two elements of AE.
  • Journal of Medical Devices 01/2015; DOI:10.1115/1.4029508 · 0.62 Impact Factor
  • Alfred S Song, Amer M. Najjar, Kenneth R Diller
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    ABSTRACT: This study was conducted to compare the heat shock responses of cells grown in two- (2D) and three-dimensional (3D) culture environments as indicated by the level of Heat Shock Protein 70 expression and the incidence of apoptosis and necrosis of prostate cancer cell lines in response to graded thermal stress. PC3 cells were stably transduced with a dual reporter system composed of two tandem expression cassettes - a conditional heat shock protein promoter driving the expression of green fluorescent protein (HSPp-GFP) and a CMV promoter controlling the constitutive expression of a "beacon" red fluorescent protein (CMVp-RFP). Two- and three-dimensional cultures of PC3 prostate cancer cells were grown in 96-well plates for evaluation of their time-dependent response to supraphysiological temperature. To induce controlled thermal stress, culture plates were placed on a flat copper surface of a circulating water manifold that maintained the specimens within +/-0.1 degree C of a target temperature. Stress protocols included various combinations of temperature, ranging from 37-57 degree C, and exposure times of up to 2 hours. The majority of protocols were focused on temperature and time permutations where the response gradient was greatest. Post-treatment analysis by flow cytometry analysis was used to measure the incidences of apoptosis (annexin V-FITC stain), necrosis (propidium iodide (PI) stain) and HSP70 transcription (GFP expression). Cells grown in 3D compared to 2D culture showed reduced incidence of apoptosis and necrosis and a higher level of HSP70 expression in response to heat shock at the temperatures tested. Cells responded differently to thermal stress when grown in 2D and 3D cultures. Three dimensional culture appears to enhance survival plausibly by activating protective processes related to enhanced HSP70 expression. These differences highlight the importance of selecting physiologically relevant 3D models in assessing cellular thermal stress responses in experimental settings.
    Journal of Biomechanical Engineering 03/2014; 136(7). DOI:10.1115/1.4027272 · 1.75 Impact Factor
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    ABSTRACT: We have investigated thermal operating characteristics of 13 commercially available cryotherapy units (CTUs) and their associated cooling pads using IR imaging. Quantitative examination of the temperature profiles from pad IR images shows diverse, non-uniform temperature distribution patterns. The extent of heterogeneity of the temperature fields was quantified via standard image analysis methods, including thresholding, spatial gradient diagrams, and frequency histogram distributions. A primary conclusion of this study is that it is a misnomer to characterize the thermal performance of a CTU and cooling pad combination in terms of a single therapeutic temperature.
    Journal of Biomechanical Engineering 03/2014; 136(7). DOI:10.1115/1.4027270 · 1.75 Impact Factor
  • Sepideh Khoshnevis, Natalie K Craik, Kenneth R Diller
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    ABSTRACT: Localized cooling is widely used in treating soft tissue injuries by modulating swelling, pain, and inflammation. One of the primary outcomes of localized cooling is vasoconstriction within the underlying skin. It is thought that in some instances, cryotherapy may be causative of tissue necrosis and neuropathy via cold-induced ischaemia leading to nonfreezing cold injury (NFCI). The purpose of this study is to quantify the magnitude and persistence of vasoconstriction associated with cryotherapy. Data are presented from testing with four different FDA approved cryotherapy devices. Blood perfusion and skin temperature were measured at multiple anatomical sites during baseline, active cooling, and passive rewarming periods. Local cutaneous blood perfusion was depressed in response to cooling the skin surface with all devices, including the DonJoy (DJO, p = 2.6 × 10(-8)), Polar Care 300 (PC300, p = 1.1 × 10(-3)), Polar Care 500 Lite (PC500L, p = 0.010), and DeRoyal T505 (DR505, p = 0.016). During the rewarming period, parasitic heat gain from the underlying tissues and the environment resulted in increased temperatures of the skin and pad for all devices, but blood perfusion did not change significantly, DJO (n.s.), PC300 (n.s.), PC500L (n.s.), and DR505 (n.s.). The results demonstrate that cryotherapy can create a deep state of vasoconstriction in the local area of treatment. In the absence of independent stimulation, the condition of reduced blood flow persists long after cooling is stopped and local temperatures have rewarmed towards the normal range, indicating that the maintenance of vasoconstriction is not directly dependent on the continuing existence of a cold state. The depressed blood flow may dispose tissue to NFCI.
    Knee Surgery Sports Traumatology Arthroscopy 02/2014; DOI:10.1007/s00167-014-2911-y · 2.68 Impact Factor
  • Sepideh Khoshnevis, Natalie Craik, Kenneth R. Diller
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    ABSTRACT: Localized cooling is commonly used following orthopedic surgery and in sports medicine to reduce swelling, pain, inflammation, metabolism, muscle spasm, and bleeding[1,2]. The therapeutic application of cold therapy has a long history dating from the time of Hippocrates and has been widely documented in the literature[3,4]. Nonetheless, there remains to the present time considerable controversy over the appropriate protocol for application of cryotherapy and the risk factors associated with its use[5].
    ASME 2013 Summer Bioengineering Conference; 06/2013
  • Natalie K. Craik, Sepideh Khoshnevis, Kenneth R. Diller
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    ABSTRACT: Orthopedic surgery and sports medicine commonly use cryotherapy to reduce inflammation, alleviate pain, lower the chance of secondary hypoxic injury, and decrease hematoma formation [1,2]. Methods of cryotherapy vary widely in their sophistication, ranging from bags of ice or freezable gel packs to liquid perfusion cryotherapy devices. These perfusion cryotherapy devices circulate near 0°C water through a flexible bladder, resulting in localized tissue cooling.
    ASME 2013 Summer Bioengineering Conference; 06/2013
  • Kenneth R. Diller
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    ABSTRACT: This presentation will describe the design of several new classes of devices for low temperature therapeutic procedures and the results of initial tests on humans. The devices are used for cryotherapy and for induction of core temperature reduction. Their operation is based on new methods to induce targeted behaviors of the human thermoregulatory system. More than 300 human trials have been conducted that will be presented and discussed. Extensive data records include skin and core temperature measurements, and superficial and deep cutaneous blood flow. Computer simulation models for local and systemic heat transfer behavior during therapeutic cooling include integrated effects such as regional modulation of blood flow, local thermal boundary conditions, and thermoregulatory control schemes.
    Cryobiology 06/2013; 66(3):351. DOI:10.1016/j.cryobiol.2013.02.040 · 1.64 Impact Factor
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    ABSTRACT: This paper presents an updated and augmented version of the Wissler human thermoregulation model that has been developed continuously over the past 50 years. The existing Fortran code is translated into C with extensive embedded commentary. A graphical user interface (GUI) has been developed in Python to facilitate convenient user designation of input and output variables and formatting of data presentation. Use of the code with the GUI is described and demonstrated. New physiological elements were added to the model to represent the hands and feet, including the unique vascular structures adapted for heat transfer associated with glabrous skin. The heat transfer function and efficacy of glabrous skin is unique within the entire body based on the capacity for a very high rate of blood perfusion and the novel capability for dynamic regulation of blood flow. The model was applied to quantify the absolute and relative contributions of glabrous skin flow to thermoregulation for varying levels of blood perfusion. The model also was used to demonstrate how the unique features of glabrous skin blood flow may be recruited to implement thermal therapeutic procedures. We have developed proprietary methods to manipulate the control of glabrous skin blood flow in conjunction with therapeutic devices and simulated the effect of these methods with the model.
    Journal of Biomechanical Engineering 02/2013; 135(2):021006. DOI:10.1115/1.4023383 · 1.75 Impact Factor
  • Sepideh Khoshnevis, Kenneth R. Diller
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    ABSTRACT: Cryotherapy has been used in the treatment of soft tissue trauma and other ailments since the time of Hippocrates. Currently it is commonly applied in conjunction with surgical procedures and by athletic trainers and physical therapists to control pain, swelling, bleeding, and inflammation. Localized cooling also results in slowing of the nerve conduction velocity and reduced muscle spasm and secondary hypoxic injury1,2. Cooling is commonly used for soft tissue injuries in combination with rest, compression and elevation to minimize inflammation.
    ASME 2012 Summer Bioengineering Conference; 06/2012
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    ABSTRACT: Glabrous (hairless) skin found on the hands, feet, face, and ears is a unique component of the thermoregulatory system. Its anatomy and control physiology differ markedly from those of the rest of the skin. Glabrous regions contain vascular networks capable of supporting large blood flows due to the presence of highly tortuous and densely packed arteriovenous anastomoses (AVAs) and associated venous collecting networks [1]. When dilated, these vessels bring large volumes of blood close to the body surface where they function as highly efficient heat exchangers. Furthermore, the manner in which this blood flow is controlled is very unique, exhibiting, for example, rapid and high-magnitude responses, as well as a greater sensitivity to central core signals [1]. In this light, glabrous skin is an important but often overlooked tool the body uses to rapidly and finely adjust energy balance to maintain thermal equilibrium.
    ASME 2012 Summer Bioengineering Conference; 06/2012
  • Kenneth R. Diller
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    ABSTRACT: Bioheat transfer is a field with origins in medical applications that date to thousands of years ago. It has long been appreciated that manipulation of temperature and energy could have significant therapeutic benefits. However, prior to the Second World War, nearly all work in this field was based on empirical studies, many of which were guided by brilliant insights of medical and life scientists. In more recent times, the principles and methods of heat transfer have been applied systematically, and often times in conjunction with highly synergistic collaborations with physicians and biologists, to achieve remarkable advances that have translated to important innovations in life science and medicine. The following discussion presents a limited range of comments concerning work accomplished by researchers associated with the ASME Bioengineering Division.
    ASME 2012 Summer Bioengineering Conference; 06/2012
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    ABSTRACT: Sub-lethal temperature elevations in the tumour incurred during laser cancer therapy can induce heat shock protein (HSP) expression leading to enhanced tumour survival and recurrence. Nanoshells utilised in combination with laser therapy can potentially enable selective heat deposition, greater thermal injury, and diminished HSP expression in the tumour. The study objective was to measure the distribution of temperature and HSP expression in prostate tumours in response to laser therapy alone or with nanoshells to determine if these combinatorial therapies can minimise HSP expression. PC3 cells were inoculated in the backs of CB17-Prkd c SCID/J mice and treated with external laser irradiation (wavelength of 810 nm, irradiance of 5 W/cm(2), spot size of 5 mm, and heating duration of 3 min) alone or in combination with gold nanoshells (diameter of 55 nm and outer gold shell thickness of 10 nm) introduced into the tumour 24 h prior to laser treatment. Magnetic resonance temperature imaging was used to measure the distribution of temperature elevation in the tumours during laser treatment. Tumours were sectioned 16 h following laser treatment, stained for Hsp27 and Hsp70, imaged with a confocal microscope, and HSP expression levels were quantified as a function of depth in the tumours. Maximum temperature elevations at the tumour surface were 28°C for laser treatment only and 50°C for laser heating in combination with gold nanoshells. Laser therapy alone caused significant induction of HSP expression in the first few millimeters of the tumour depth, whereas decreasing HSP expression occurred with greater tumour depth. Tumours treated with laser and nanoshells experienced substantial temperatures (73-78°C) at the tumour surface and temperatures greater than 53°C in the first few millimeters which eliminated HSP expression. Inclusion of nanoshells in laser therapy can provide a mechanism for enhancing heat deposition capable of eliminating HSP expression within a larger tumour region compared to laser heating alone.
    International Journal of Hyperthermia 12/2011; 27(8):791-801. DOI:10.3109/02656736.2011.607485 · 2.77 Impact Factor
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    ABSTRACT: We discuss and give examples of the use of selective laser sintering to fabricate solid macroscopic models of microscopic specimens that have been imaged with a confocal microscope. The digital image processing necessary to create structurally sound models of both translucent and opaque specimens is presented. The fabricated models offer the ultimate in data visualization since they can be physically handled and manipulated to investigate the shape and features of the specimen. Such a powerful visualization tool is useful in both research and educational environments.
    Journal of Microscopy 08/2011; 169(3):383 - 389. DOI:10.1111/j.1365-2818.1993.tb03314.x · 1.63 Impact Factor
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    ABSTRACT: In this paper an approach for improving the quality of 3-D microscopic images obtained through optical serial sectioning is described and implemented. A serially sectioned image is composed of a sequence of 2-D images obtained by incrementing the focusing plane of the microscope through the specimen of interest; ideally, the image obtained at each focusing plane should be in focus, and should contain information lying only within that plane. In practice, however, the images obtained contain redundant information from neighbouring focusing planes and are blurred by a three-dimensional low-pass distortion. These degradations are a consequence of the limited aperture of any optical system; using principles of geometric optics and allowing for the passage of light through the specimen, we are able to demonstrate that the microscope distortion can be described as a linear system, if the absorption of the specimen is assumed to be linear and non-diffractive. The transfer function of the microscope is found to zero a biconic region of 3-D spatial frequencies orientated along the optical axis; a closed-form expression is derived for the low-pass transfer function of the microscope outside the region of missing frequencies. The planar resolution of the serial sections can be greatly improved by convolving the image obtained with the inverse of the low-pass distortion function, although the missing cone of frequencies is not recoverable. The reconstruction technique is demonstrated using both simulated images, to demonstrate more clearly the effects of the distortion and the accuracy of the subsequent reconstruction, and actual experiments with a pollen grain and a stained preparation of human cerebellum tissue.
    Journal of Microscopy 08/2011; 153(2):205 - 221. DOI:10.1111/j.1365-2818.1989.tb00561.x · 1.63 Impact Factor
  • Robert J. Roselli, Kenneth R. Diller
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    ABSTRACT: An important outcome of the VaNTH ERC for Bioengineering Education Technologies is direct evidence of the effectiveness of challenge-based learning. This is a form of active learning that is based on the principle that the most effective learning environment is not only knowledge-centered, but is also learner-centered, assessment-centered and community-centered. Challenges presented in such a learning environment are most effective when they are based on real life applications that are of interest to the learner, but require the learner to extend his/her knowledge base before the challenge can be solved. By design, some of the necessary knowledge is gained outside the classroom and some is gleaned by student activities conducted inside the classroom. An objection to the use of active learning raised by some instructors is that less material can be covered in the classroom than in a traditional lecture-based course. Although this is true, it is not true that less material can be covered in an active learning course than in a lecture-only course. Instead, concepts that are easy to grasp can be moved to out-of-class activities, allowing more in-class time for the more difficult concepts. We have developed resources that can assist instructors of biotransport to begin adopting the challenge-based approach.
    ASME 2011 Summer Bioengineering Conference; 06/2011
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    ABSTRACT: Localized cooling is commonly used after orthopedic surgery and in sports medicine to reduce bleeding, inflammation, metabolism, muscle spasm, pain, and swelling following musculoskeletal trauma and injury. The therapeutic application of cold therapy has a long history dating from the time of Hippocrates and has been widely documented in the literature1–3. Nonetheless, there remains to the present time considerable controversy over the appropriate protocol for application of cryotherapy. One extreme camp advocates continuous use of cryotherapy to a treatment site with no break in cooling for days or even weeks4–5, whereas other practitioners recommend a maximum application duration of 20 to 30 minutes followed by a cessation period of about 2 hours6–7. Although continuous cooling appears to be tolerated by many patients, there has been a large number of reported incidences in which continuous application of cryotherapy device led directly to extensive tissue necrosis and/or nerve injury in the treatment area, sometimes with dire medical consequences6,8.
    ASME 2011 Summer Bioengineering Conference; 06/2011
  • Kenneth R Diller
    Journal of burn care & research: official publication of the American Burn Association 03/2011; 32(2):e33-4; author reply e35-6. DOI:10.1097/BCR.0b013e31820ab159 · 1.55 Impact Factor
  • Robert J. Roselli, Kenneth R. Diller
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    ABSTRACT: Applications of the macroscopic species conservation equation discussed in Chap. 13 are used extensively in biotransport. However, the macroscopic approach has important practical restrictions. It is limited to predicting concentrations, fluxes, or flows that are spatially averaged. If concentrations or fluxes have significant spatial variations, a different approach must be applied. Rather than apply the species conservation principle to the entire system, a microscopic portion of the system is analyzed. The resulting expression will be a differential equation that is valid at any position within the boundaries of the system. Boundary conditions that are specific to the problem at hand must be applied to find a solution for a particular system. Applications include axial variations of oxygen and carbon dioxide in capillaries, axial variations in salt concentration in the Loop of Henle, radial concentration variations of urea in tissue or hemodialyzers, solute concentration variations in porous microcapsules, etc.
  • Kenneth R. Diller
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    ABSTRACT: The irradiation of tissue by laser light results in the absorption of energy. Since this is a fully dissipative process, the consequence is that the increment in energy is expressed entirely as a heat transfer absorbed by the tissue. In conjunction with this absorption, there will be an increase in the energy stored locally in the tissue as a function of the geometric pattern of absorption. Two primary mechanisms of energy storage are encountered most frequently during laser irradiation: sensible and latent. Sensible storage results in a change in temperature and latent in a change in phase. The two mechanisms may occur simultaneously or singularly, depending on the initial state of the tissue and the intensity of the irradiation. A local increase in the temperature will cause a diffusion of heat to surrounding areas that are cooler. Therefore, the analysis of heat transfer is an important and relevant component of understanding the process and consequences of laser irradiation of tissue. Phase change and temperature elevation are often a direct source of injury to tissue.
    12/2010: pages 353-397;

Publication Stats

2k Citations
324.15 Total Impact Points

Institutions

  • 1979–2014
    • University of Texas at Austin
      • • Department of Biomedical Engineering
      • • Institute for Computational Engineering and Sciences
      • • Department of Mechanical Engineering
      • • Department of Electrical & Computer Engineering
      Austin, Texas, United States
  • 2006
    • Virginia Polytechnic Institute and State University
      • Department of Mechanical Engineering
      Blacksburg, VA, United States
  • 1989–1991
    • University of Texas at Dallas
      Richardson, Texas, United States
  • 1988
    • University of Texas Southwestern Medical Center
      • Department of Surgery
      Dallas, TX, United States
    • Umeå University
      Umeå, Västerbotten, Sweden
  • 1982–1985
    • Concordia University Texas
      Austin, Texas, United States