Just Science

Latest Episodes:

Just PMI Estimation Research_Special Release_013 Jul 24, 2017

Show notes

Dr. LaMotte and Dr. Wells discuss their NIJ funded research on PMI and how it can help crime scene investigators. This is their abstract submitted for the R&D Symposium: "To our knowledge an estimate of time since death is almost never accompanied by the kind of mathematically explicit probability statement that is the standard in most scientific disciplines. This has been a problem both for death investigation casework (and court testimony) and for research, because scientists have not known how to design decomposition experiments to provide adequate statistical power for postmortem interval (PMI) estimation. We have been developing methods for calculating statistical confidence limits about a PMI estimate based on either continuous quantitative or categorical data. The examples we present are from forensic entomology, but the approach is suitable for any postmortem variable. To do this we extended and adapted the time-tested statistical method of inverse prediction (IP, also called calibration) to the PMI estimation setting. Methods to produce valid p-values for this process are known for single, quantitative y and x that follow a linear regression relation and with y having constant variance. Some exist for multivariate y, but only for settings where y has constant variance. Many measurements used for PMI estimation do not fit these criteria. The current project builds on earlier work in which we developed IP methods for non-constant variance of a single, quantitative y (e.g. estimating carrion maggot age using a single size measurement, Wells and LaMotte 1995), and in which we developed the first ever method for IP based on categorical data (e.g. estimating PMI based on carrion insect succession, LaMotte and Wells 2000). One possible barrier to the adoption of these new inverse prediction methods by researchers and death investigators has been that they are not implemented in statistical software packages. In this presentation we will show how IP using categorical data can be done by simply reading a table. Concerning quantitative data we will show how inverse prediction of PMI can be performed using statistical analysis software already widely available for general linear mixed models, where the statistical theory and methodology are well-established. We will show how flexible models using polynomial splines can be fit for both the means and variance-covariance matrices, and how to use dummy variables over a grid of values of x to get the p-values required for confidence sets automatically. Attendees familiar with mixed models and their applications will be able to implement these methods in standard statistical packages. Statistical Methods for Combining Multivariate and Categorical Data in Postmortem Interval Estimation 2013‐DN‐BXK042 Lynn R. LaMotte,1 and Jeffrey D. Wells2 1Biostatistics Program, LSU School of Public Health To learn more visit www.ForensicCOE.org

Just Bath Salts_Special Release_012 Jul 17, 2017

Show notes

Just Bath Salts In this special release episode of the 2017 NIJ R&D Symposium, Just Science interviews Lindsay Glicksberg, a student from Sam Houston State University. This is an excerpt from the abstract submitted by the guest, Lindsay Glicksberg explaining the research discussed in this episode: The ongoing proliferation of designer drugs present a variety of public health and safety concerns. Synthetic cathinones are capable of producing a variety of psychostimulant effects. According to the National Forensic Laboratory Information System (NFLIS), their use has escalated. Forensic laboratories must be able to identify these new drugs as part of antemortem and postmortem toxicology investigations. Due to limitations in immunoassay-based screening technologies, many forensic toxicology laboratories must rely on chromatographic-based screening approaches in order to detect these drugs in biological evidence. The detection of drugs is heavily dependent upon the stability of the drug in biological matrices, information that is relatively limited for synthetic cathinones. This research presents a validated method for the quantification of twenty- two synthetic cathinones in urine and blood using liquid chromatography/quadrupole time of flight mass spectrometry (LC/Q-TOF-MS). The validated method was used to systematically evaluate the stability of synthetic cathinones in blood and urine over a six-month period. Drug stability was assessed in terms of pH, temperature, matrix, concentration-dependence and chemical properties. This episode is funded by the National Institute of Justice's Forensic Technology Center of Excellence.

Just One Pot Methamphetamine_Special Release_011 Jul 10, 2017

Show notes

In this special release season, Just Science will be covering presenters at the National Institute of Justice’s Research and Development Symposium Meeting held in conjunction with the American Academy of Forensic Sciences annual meeting in New Orleans, Louisiana in February of 2017. The first of four episodes, funded by the National Institute of Justice’s Forensic Technology Center of Excellence, we interviewed Dr. Jarrad Wagner, from Oklahoma State University. This NIJ funded research is striving to make law enforcement officials and their communities safer by determining practical ways to detect methamphetamine clandestine laboratories through water waste systems.

Just Hairy Isotopes_Numbers_010 Jun 26, 2017

Show notes

Just Hairy Isotopes In episode ten of Just Science, funded by the National Institute of Justice’s Forensic Technology Center of Excellence [Award 2016-MU-BX-K110], we spoke with Dr. Gwyneth Gordon, from Arizona State University. Dr. Gordon and her team have developed methods to use the isotopic abundance of elements in hair to learn more about the history of an individual. This NIJ funded research, used in the investigation of unidentified dead, isotopic analysis will measures strontium, trace elements, and even rare earth minerals to shed light on diet, birthplace and residential history. https://forensiccoe.org/?p=4412&preview=true

Just Blood Spatter_Numbers_009 Jun 19, 2017

Show notes

Just Blood Spatter In episode nine of Just Science, funded by the National Institute of Justice’s Forensic Technology Center of Excellence [Award 2016-MU-BX-K110], we spoke with Dr. Marc Smith, from the Georgia Institute of Technology. Dr. Smith’s NIJ funded research in blood spatter has connected computational fluid dynamics with empirical studies to improve the understanding of blood spatter onto solid, slanted surfaces. His work looks at many variables, including droplet size, speed, surface roughness and wettability. https://forensiccoe.org/ep9s1/

Just the Facts About Campus Sexual Assault_Numbers_008 Jun 12, 2017

Show notes

In episode eight of Just Science, funded by the National Institute of Justice’s Forensic Technology Center of Excellence [Award 2016-MU-BX-K110], we spoke with Dr. Christopher Krebs, a Senior Research Social Scientist at RTI International. Dr. Krebs’ research has shed light on the problem of sexual assault on college campuses and prisons. We discuss the history of RTI research in the area and how to interpret the data considering the methodology of social science. This could be a lesson in data interpretation and statistics that may be useful for forensic scientists, but it also raises the awareness of an issue of which the magnitude is not yet fully understood. Some content in this podcast is sensitive and may evoke emotional responses or may not be appropriate for younger audiences. https://forensiccoe.org/ep8s1/

Just Dry Bones_Numbers_007 Jun 05, 2017

Show notes

Just Dry Bones: In the seventh episode of Just Science, funded by the National Institute of Justice’s Forensic Technology Center of Excellence [Award 2016-MU-BX-K110], guest speakers Dr. Melissa Connor, Dr. Eriek Hansen, and Christiane Baigent discuss their NIJ funded research. A study was launched in late 2015 using two methods, Bioelectrical impedance analysis (BIA) and Total Body Desiccation. Observations from three years of study at Colorado Mesa University created a qualitative scoring system the Total Body Desiccation Score (TBDS) showing major changes over time by desiccated remains. Visit the FTCOE website to learn more at https://forensiccoe.org/e7s1/

Just Budgets_Numbers_006 May 29, 2017

Show notes

In the sixth episode of Just Science, funded by the National Institute of Justice’s Forensic Technology Center of Excellence [Award 2016-MU-BX-K110], guest speaker Dr. Paul Speaker discusses the FORESIGHT program. Dr. Speaker, an Associate Professor at West Virginia University, will describe how The FORESIGHT program helps crime laboratories manage their finances and track their performance by using data. This episode will stress the importance of knowing business jargon, and how it can help a crime laboratories persuade policy makers. Listen and subscribe to learn more.

Just DNA Mixture Interpretation_Numbers_005 May 22, 2017

Show notes

DNA Mixture Interpretation In the fifth episode of Just Science, funded by the National Institute of Justice’s Forensic Technology Center of Excellence [Award 2016-MU-BX-K110], we have guest speaker Dr. Catherine Grgicak speaking about one of the hot topics in forensic science, DNA Mixture interpretation. Dr. Grgicak and her colleagues at Boston University have developed tools and resources that are openly available to the forensic science community. This episode covers the CEESIt (Computational Evaluation of Evidentiary Signal) and NOCIt (Number Of Contributors) tools along with some of the other contributions that Dr. Grgicak and her colleagues have made to the forensic community. Listen and subscribe to learn more.

Just Subjective Probability_ Numbers_004 May 15, 2017

Show notes

SUBJECTIVE PROBABILITY For episode four of Just Science, funded by the National Institute of Justice’s Forensic Technology Center of Excellence [Award 2016-MU-BX-K110], we will be diving into the world of statistics and how it applies forensic case work with Dr. Christophe Champod and Dr. Tacha Hicks from the University of Lausanne. They, along with RTI International resident fingerprint expert, co-host Heidi Eldridge, will be discussing subjective probability and how it can be used in forensic science. There are many different viewpoints and methods about how to use statistical analysis in the courtroom and this episode will help listeners better understand these differing viewpoints. Subscribe and listen to learn more about how logical thinking must be applied appropriately when determining subjective probability through examples given by the guests. Visit the landing page to learn more: https://forensiccoe.org/episode-four-subjective-probability/

Our TOPPODCAST Picks

Follow Us

Stay Connected

Related Podcasts

Links

Stay Connected