The Experts below are selected from a list of 3987 Experts worldwide ranked by ideXlab platform
Sandra M Brown - One of the best experts on this subject based on the ideXlab platform.
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dark adapted pupil diameter as a function of age measured with the neuroptics pupillometer
Journal of Refractive Surgery, 2010Co-Authors: Jay C Bradley, Karl C Bentley, Aleem I Mughal, Hari Bodhireddy, Sandra M BrownAbstract:Purpose To measure the dark-adapted pupil diameter of normal research participants in their second through ninth decades of life using the NeurOptics pupillometer (Neuroptics Inc). Methods Individuals aged 18 to 80 years with no history of eye disease or injury, intraocular surgery, or use of systemic antihistamines or opiates were recruited. After 2 minutes of adaptation at 1 lux illumination, the right dark-adapted pupil diameter was measured using the NeurOptics pupillometer, with accommodation controlled by distance fixation. The NeurOptics pupillometer reported a mean dark-adapted pupil diameter and a standard deviation of the mean, which were analyzed as a function of age-decade. Results Two-hundred sixty-three individuals participated. For participants aged 18 to 19 years (n=6), the mean dark-adapted pupil diameter was 6.85 mm (range: 5.6 to 7.5 mm); 20 to 29 years (n=66), 7.33 mm (range: 5.7 to 8.8 mm); 30 to 39 years (n=50), 6.64 mm (range: 5.3 to 8.7 mm); 40 to 49 years (n=51), 6.15 mm (range: 4.5 to 8.2 mm); 50 to 59 years (n=50), 5.77 mm (range: 4.4 to 7.2 mm); 60 to 69 years (n=30), 5.58 mm (range: 3.5 to 7.5 mm); 70 to 79 years (n=6), 5.17 mm (range: 4.6 to 6.0 mm); and 80 years (n=4), 4.85 mm (range: 4.1 to 5.3 mm). These values were consistent with studies using Infrared Photography. The standard deviation was >0.1 mm in 10 (3.8%) participants, all of whom were younger than 55 years. Conclusions The dark-adapted pupil diameter is an important clinical variable when planning refractive surgery. Surgeons can compare a patient's dark-adapted pupil diameter with the results of this population study to identify outlier measurements, which may be erroneous, and repeat testing prior to surgery.
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clinical performance of a handheld digital Infrared monocular pupillometer for measurement of the dark adapted pupil diameter
Journal of Cataract and Refractive Surgery, 2010Co-Authors: Jay C Bradley, Karl C Bentley, Aleem I Mughal, Sandra M BrownAbstract:Purpose To compare the accuracy of a handheld Infrared digital pupillometer and digital Infrared Photography for measurement of the dark-adapted pupil diameter. Setting Department of Ophthalmology and Visual Sciences, Texas Tech University Health Sciences Center, Lubbock, Texas, USA. Methods The right horizontal pupil diameter in healthy volunteers was measured using a NeurOptics PLR-200 pupillometer and then videographed using the Infrared function of a CyberShot video camera after 2 minutes and 5 minutes dark adaptation at 1 lux ambient illumination. The best still image was extracted from the video file, and the horizontal pupil diameter was determined by comparison against an internal photographic length standard using digital image software. Accommodation and alertness were controlled during testing. Results The mean horizontal pupil diameter by Infrared Photography after 2 minutes of dark adaptation by subject age was 7.71 mm for ages 20 to 29 years, 6.80 mm for ages 30 to 39 years, 6.53 mm for ages 40 to 49 years, 5.94 mm for ages 50 to 59 years, and 6.01 mm for ages 60 to 69 years. The mean difference (Infrared Photography minus pupillometer) was +0.09 mm (range +0.30 to −0.14 mm) at 2 minutes of adaptation and +0.07 mm (range +0.25 to −0.13 mm) at 5 minutes. Conclusions The pupillometer accurately measured the horizontal pupil diameter at 1 lux, with no measurement more than 0.3 mm different from Infrared Photography measurements. The pupillometer had a slight negative bias that is unlikely to introduce an error greater than 0.5 mm in clinical measurements. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.
Adrian Renshaw - One of the best experts on this subject based on the ideXlab platform.
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the effects of heat on the physical and spectral properties of bloodstains at arson scenes
Forensic Science International, 2021Co-Authors: Belinda Bastide, Glenn Porter, Adrian RenshawAbstract:Abstract This study examines the spectral characteristics of blood after being exposed to intense heat within a structural fire. Fire and intense heat have previously been understood to destroy or chemically change bloodstain evidence so that traditional forensic science recovery techniques are rendered ineffectual. Understanding the effects of the denaturation process and physical changes that occur to blood when exposed to heat may develop innovative forensic investigation methods, including the use of reflected Infrared Photography to enhance the recording of bloodstains. This research revealed that the denaturation of blood, specifically changes to the haemoglobin state from oxyhaemoglobin to methaemoglobin, resulted in the heat affected blood having a more optimal spectral target range within the Infrared region when exposed to heat> 200 °C. It was observed both qualitatively and quantitatively using spectrophotometry, that there is a relationship between the appearance, viscosity and Infrared absorption properties of blood when exposed to different temperatures as experienced in fire. This result indicated the increased potential for reflected Infrared Photography to be utilised as an effective tool for crime scene evidence recovery of bloodstains from arson scenes involving fire.
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detection of latent bloodstains at fire scenes using reflected Infrared Photography
Forensic Science International, 2019Co-Authors: Belinda Bastide, Glenn Porter, Adrian RenshawAbstract:Bloodstain evidence is an element of crime scene investigation often found at scenes involving violence. Setting fire to the scene is a method sometimes used by offenders of crime in an attempt to conceal evidence. Fire often produces thick soot as a by-product of the combustion and has the potential to cover bloodstain patterns rendering them latent. There is limited published material offering a method of detecting bloodstains hidden beneath dense soot deposits caused by fire. This project employed a modified digital single-lens reflex (SLR) camera to investigate the application of reflected Infrared Photography to detect latent bloodstain evidence beneath varying deposited overlaying soot densities. The potential of this technique was examined by photographing blood samples beneath soot from a scaled fire simulation. A qualitative evaluation was completed by comparing images taken of a series of samples using both reflected Infrared and standard visible light Photography and corroborated with quantitative image analysis to support the findings. Results indicate that Infrared Photography can reveal latent bloodstains beneath a dense layer of soot in excess of ρ2.3 (550nm) density with substantial clarity. The success of this technique is dependent on specific optical and specimen parameters. These parameters include (i) the reflective properties of the background surface, (ii) the spectral absorption properties of blood and (iii) the ability of Infrared wavelengths to transmit through the soot layer. Reflected Infrared Photography may provide crime scene examiners with a specialised field recording method that is easily executed and non-destructive to assist in visualising and locating latent bloodstain patterns beneath dense layers of soot.
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detection of latent bloodstains beneath painted surfaces using reflected Infrared Photography
Journal of Forensic Sciences, 2012Co-Authors: Andrew Farrar, Glenn Porter, Adrian RenshawAbstract:Bloodstain evidence is a highly valued form of physical evidence commonly found at scenes involving violent crimes. However, painting over bloodstains will often conceal this type of evidence. There is limited research in the scientific literature that describes methods of detecting painted-over bloodstains. This project employed a modified digital single-lens reflex camera to investigate the effectiveness of Infrared (IR) Photography in detecting latent bloodstain evidence beneath a layer or multiple layers of paint. A qualitative evaluation was completed by comparing images taken of a series of samples using both IR and standard (visible light) Photography. Further quantitative image analysis was used to verify the findings. Results from this project indicate that bloodstain evidence can be detected beneath up to six layers of paint using reflected IR; however, the results vary depending on the characteristics of the paint. This technique provides crime scene specialists with a new field method to assist in locating, visualizing, and documenting painted-over bloodstain evidence.
Matthew Sturm - One of the best experts on this subject based on the ideXlab platform.
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recording microscale variations in snowpack layering using near Infrared Photography
Journal of Glaciology, 2010Co-Authors: Ken D Tape, Nick Rutter, Hanspeter Marshall, Richard Essery, Matthew SturmAbstract:Deposition of snow from precipitation and wind events creates layering within seasonal snowpacks. The thickness and horizontal continuity of layers within seasonal snowpacks can be highly variable, due to snow blowing around topography and vegetation, and this has important implications for hydrology, remote sensing and avalanche forecasting. In this paper, we present practical field and post-processing protocols for recording lateral variations in snow stratigraphy using near-Infrared (NIR) Photography. A Fuji S9100 digital camera, modified to be sensitive to NIR wavelengths, was mounted on a rail system that allowed for rapid imaging of a 10 m long snow trench excavated on the north side of Toolik Lake, Alaska (68°3? N, 149°36? W). Post-processing of the images included removal of lens distortion and vignetting. A tape measure running along the base of the trench provided known locations (control points) that permitted scaling and georeferencing. Snow layer heights estimated from the NIR images compared well with manual stratigraphic measurements made at 0.2 m intervals along the trench (n = 357, R2 = 0.97). Considerably greater stratigraphic detail was captured by the NIR images than in the manually recorded profiles. NIR imaging of snow trenches using the described protocols is an efficient tool for quantifying continuous microscale variations in snow layers and associated properties.
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instruments and methods recording microscale variations in snowpack layering using near Infrared Photography
Journal of Glaciology, 2010Co-Authors: Ken D Tape, Nick Rutter, Hanspeter Marshall, Richard Essery, Matthew SturmAbstract:Deposition of snow from precipitation and wind events creates layering within seasonal snowpacks. The thickness and horizontal continuity of layers within seasonal snowpacks can be highly variable, due to snow blowing around topography and vegetation, and this has important implications for hydrology, remote sensing and avalanche forecasting. In this paper, we present practical field and post- processing protocols for recording lateral variations in snow stratigraphy using near-Infrared (NIR) Photography. A Fuji S9100 digital camera, modified to be sensitive to NIR wavelengths, was mounted on a rail system that allowed for rapid imaging of a 10 m long snow trench excavated on the north side of Toolik Lake, Alaska (68838 0 N, 149836 0 W). Post-processing of the images included removal of lens distortion and vignetting. A tape measure running along the base of the trench provided known locations (control points) that permitted scaling and georeferencing. Snow layer heights estimated from the NIR images compared well with manual stratigraphic measurements made at 0.2 m intervals along the trench (n = 357, R 2 = 0.97). Considerably greater stratigraphic detail was captured by the NIR images than in the manually recorded profiles. NIR imaging of snow trenches using the described protocols is an efficient tool for quantifying continuous microscale variations in snow layers and associated properties.
Jay C Bradley - One of the best experts on this subject based on the ideXlab platform.
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dark adapted pupil diameter as a function of age measured with the neuroptics pupillometer
Journal of Refractive Surgery, 2010Co-Authors: Jay C Bradley, Karl C Bentley, Aleem I Mughal, Hari Bodhireddy, Sandra M BrownAbstract:Purpose To measure the dark-adapted pupil diameter of normal research participants in their second through ninth decades of life using the NeurOptics pupillometer (Neuroptics Inc). Methods Individuals aged 18 to 80 years with no history of eye disease or injury, intraocular surgery, or use of systemic antihistamines or opiates were recruited. After 2 minutes of adaptation at 1 lux illumination, the right dark-adapted pupil diameter was measured using the NeurOptics pupillometer, with accommodation controlled by distance fixation. The NeurOptics pupillometer reported a mean dark-adapted pupil diameter and a standard deviation of the mean, which were analyzed as a function of age-decade. Results Two-hundred sixty-three individuals participated. For participants aged 18 to 19 years (n=6), the mean dark-adapted pupil diameter was 6.85 mm (range: 5.6 to 7.5 mm); 20 to 29 years (n=66), 7.33 mm (range: 5.7 to 8.8 mm); 30 to 39 years (n=50), 6.64 mm (range: 5.3 to 8.7 mm); 40 to 49 years (n=51), 6.15 mm (range: 4.5 to 8.2 mm); 50 to 59 years (n=50), 5.77 mm (range: 4.4 to 7.2 mm); 60 to 69 years (n=30), 5.58 mm (range: 3.5 to 7.5 mm); 70 to 79 years (n=6), 5.17 mm (range: 4.6 to 6.0 mm); and 80 years (n=4), 4.85 mm (range: 4.1 to 5.3 mm). These values were consistent with studies using Infrared Photography. The standard deviation was >0.1 mm in 10 (3.8%) participants, all of whom were younger than 55 years. Conclusions The dark-adapted pupil diameter is an important clinical variable when planning refractive surgery. Surgeons can compare a patient's dark-adapted pupil diameter with the results of this population study to identify outlier measurements, which may be erroneous, and repeat testing prior to surgery.
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clinical performance of a handheld digital Infrared monocular pupillometer for measurement of the dark adapted pupil diameter
Journal of Cataract and Refractive Surgery, 2010Co-Authors: Jay C Bradley, Karl C Bentley, Aleem I Mughal, Sandra M BrownAbstract:Purpose To compare the accuracy of a handheld Infrared digital pupillometer and digital Infrared Photography for measurement of the dark-adapted pupil diameter. Setting Department of Ophthalmology and Visual Sciences, Texas Tech University Health Sciences Center, Lubbock, Texas, USA. Methods The right horizontal pupil diameter in healthy volunteers was measured using a NeurOptics PLR-200 pupillometer and then videographed using the Infrared function of a CyberShot video camera after 2 minutes and 5 minutes dark adaptation at 1 lux ambient illumination. The best still image was extracted from the video file, and the horizontal pupil diameter was determined by comparison against an internal photographic length standard using digital image software. Accommodation and alertness were controlled during testing. Results The mean horizontal pupil diameter by Infrared Photography after 2 minutes of dark adaptation by subject age was 7.71 mm for ages 20 to 29 years, 6.80 mm for ages 30 to 39 years, 6.53 mm for ages 40 to 49 years, 5.94 mm for ages 50 to 59 years, and 6.01 mm for ages 60 to 69 years. The mean difference (Infrared Photography minus pupillometer) was +0.09 mm (range +0.30 to −0.14 mm) at 2 minutes of adaptation and +0.07 mm (range +0.25 to −0.13 mm) at 5 minutes. Conclusions The pupillometer accurately measured the horizontal pupil diameter at 1 lux, with no measurement more than 0.3 mm different from Infrared Photography measurements. The pupillometer had a slight negative bias that is unlikely to introduce an error greater than 0.5 mm in clinical measurements. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.
Glenn Porter - One of the best experts on this subject based on the ideXlab platform.
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the effects of heat on the physical and spectral properties of bloodstains at arson scenes
Forensic Science International, 2021Co-Authors: Belinda Bastide, Glenn Porter, Adrian RenshawAbstract:Abstract This study examines the spectral characteristics of blood after being exposed to intense heat within a structural fire. Fire and intense heat have previously been understood to destroy or chemically change bloodstain evidence so that traditional forensic science recovery techniques are rendered ineffectual. Understanding the effects of the denaturation process and physical changes that occur to blood when exposed to heat may develop innovative forensic investigation methods, including the use of reflected Infrared Photography to enhance the recording of bloodstains. This research revealed that the denaturation of blood, specifically changes to the haemoglobin state from oxyhaemoglobin to methaemoglobin, resulted in the heat affected blood having a more optimal spectral target range within the Infrared region when exposed to heat> 200 °C. It was observed both qualitatively and quantitatively using spectrophotometry, that there is a relationship between the appearance, viscosity and Infrared absorption properties of blood when exposed to different temperatures as experienced in fire. This result indicated the increased potential for reflected Infrared Photography to be utilised as an effective tool for crime scene evidence recovery of bloodstains from arson scenes involving fire.
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detection of latent bloodstains at fire scenes using reflected Infrared Photography
Forensic Science International, 2019Co-Authors: Belinda Bastide, Glenn Porter, Adrian RenshawAbstract:Bloodstain evidence is an element of crime scene investigation often found at scenes involving violence. Setting fire to the scene is a method sometimes used by offenders of crime in an attempt to conceal evidence. Fire often produces thick soot as a by-product of the combustion and has the potential to cover bloodstain patterns rendering them latent. There is limited published material offering a method of detecting bloodstains hidden beneath dense soot deposits caused by fire. This project employed a modified digital single-lens reflex (SLR) camera to investigate the application of reflected Infrared Photography to detect latent bloodstain evidence beneath varying deposited overlaying soot densities. The potential of this technique was examined by photographing blood samples beneath soot from a scaled fire simulation. A qualitative evaluation was completed by comparing images taken of a series of samples using both reflected Infrared and standard visible light Photography and corroborated with quantitative image analysis to support the findings. Results indicate that Infrared Photography can reveal latent bloodstains beneath a dense layer of soot in excess of ρ2.3 (550nm) density with substantial clarity. The success of this technique is dependent on specific optical and specimen parameters. These parameters include (i) the reflective properties of the background surface, (ii) the spectral absorption properties of blood and (iii) the ability of Infrared wavelengths to transmit through the soot layer. Reflected Infrared Photography may provide crime scene examiners with a specialised field recording method that is easily executed and non-destructive to assist in visualising and locating latent bloodstain patterns beneath dense layers of soot.
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detection of latent bloodstains beneath painted surfaces using reflected Infrared Photography
Journal of Forensic Sciences, 2012Co-Authors: Andrew Farrar, Glenn Porter, Adrian RenshawAbstract:Bloodstain evidence is a highly valued form of physical evidence commonly found at scenes involving violent crimes. However, painting over bloodstains will often conceal this type of evidence. There is limited research in the scientific literature that describes methods of detecting painted-over bloodstains. This project employed a modified digital single-lens reflex camera to investigate the effectiveness of Infrared (IR) Photography in detecting latent bloodstain evidence beneath a layer or multiple layers of paint. A qualitative evaluation was completed by comparing images taken of a series of samples using both IR and standard (visible light) Photography. Further quantitative image analysis was used to verify the findings. Results from this project indicate that bloodstain evidence can be detected beneath up to six layers of paint using reflected IR; however, the results vary depending on the characteristics of the paint. This technique provides crime scene specialists with a new field method to assist in locating, visualizing, and documenting painted-over bloodstain evidence.
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the detection of latent residue tattoo ink pigments in skin using invisible radiation Photography
Australian Journal of Forensic Sciences, 2008Co-Authors: Michelle L Mckechnie, Glenn Porter, Neil E I LangloisAbstract:The identification of tattoos often provides important forensic information when investigating criminal activity. Tattoos may be used by police intelligence as a source of identification of known criminals. Tattoos may be effaced by laser surgery so that they can no longer been seen by visual inspection of the skin. However, remnants of pigment persist within the dermis. This paper describes a novel technique using Infrared Photography that can demonstrate the presence of tattoos that have been ablated by lasers. The method provides adequate detail of the tattoo's characteristics to aid in forensic identification. A literature search did not reveal any known methods of detecting latent residue inks after removal or detecting alteration of a pre-existing tattoo.