Expertly Speaking

The Latest and Greatest of Automotive Technology Has Just Been Released. Meet the Rimac Nevera.


Yuri A. Apel, BSEE, MSEM, Senior Electrical/Automotive Engineer

Rimac Nevera

Not only is this car insanely fast with incredible horsepower and torque figures (1,914 hp, 1,740 lb-ft) but it is also dripping with technology. For starters, the monocoque is full carbon fiber. Why is this important? Because the construction of carbon fiber is so strong that this vehicle will have the “most rigid structure of any car ever made”. And by the way, this structure only weighs 441 pounds!

Rimac Nevera

Next, we have the 120-kWH battery made up of 6,960 cells which delivers 1.4 MW and can charge up to 80% in 19 minutes. This all means that the battery can deliver power to the 4-electric motors in a very sophisticated way using torque vectoring. Torque vectoring is Rimac’s solution to controlling the vehicle stability in a super direct and effective way by controlling the power of each wheel independently while the vehicle is cornering. To top it off, the Nevera has an AI driver coach (for track use) and a boat load of sensors; 12 ultrasonic sensors, 13 cameras, and 6 radars.

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An Introduction to the Basics of DNA Testing


Dr. Christian G. Westring, Ph.D., Forensic Geneticist

A DNA profile can simply be regarded as a list of numbers similar to a phone number. While the individual numbers used in any given telephone number are not unique, the specific order of each number makes each telephone number unique. Similarly, DNA testing relies on identifying the number of repeats (known as alleles) at 20 or more locations (known to scientists as loci) – that can provide statistics of 1 in nonillion (30 zeros) or more.

DNA Testing

The genetic structure that contains the DNA of interest here are known as chromosomes. In humans, these chromosomes are inherited as 23 unique sets (including the sex determination chromosomes, X and Y), one chromosome inherited from mom, one from dad. The loci we employ in forensic DNA testing are distributed throughout these 23 sets of chromosomes. The number of repeat units at each locus varies from person to person, and is inherited from each parent (baring mutation, of course). Hence, we would anticipate seeing two “peaks” at each location, one from mom, and one from dad. In the event that number of repeats is the same length, it would be seen as a single peak, known as a homozygote, which is made from both parents.

DNA Testing

In order to determine the number of repeats at each locus, laboratory analysts extract DNA from the sample of interest using a variety of chemicals that removes the DNA from other cellular components. The DNA STR profile is generated through a heating and cooling process known at the Polymerase Chain Reaction – where the sample is later separated by size by an electric current – a process known as electrophoresis. In the figure above, we see to alleles – a “four” that was inherited from mom, and a “six” that was inherited from dad. Based on size, the four allele (which is smaller), will migrate faster than the six during electrophoresis. These differences in size and mobility through the gel matrix is what allows forensic scientists to differentiate DNA fragments based on size. This same concept applies to all 20-plus loci which we commonly encounter in forensic applications.

DNA Testing

In 2017, the FBI expanded the original 13 core loci (highlighted yellow) in the Combined DNA Index System (CODIS) databases and expanded to 20 loci (highlighted in green). Credit; National Institute of Standards and Technology.

Learn more about DNA applications here: Modern DNA Applications: Who was the Driver?

Dr. Christian G. Westring, Ph.D., Forensic Geneticist with DJS Associates, Inc., can be reached via email at experts@forensicDJS.com or via phone at 215-659-2010.

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How Do You Find Fault When It Is A “He Said, She Said” Accident?


Hugh B. Borbidge, BSME, Director of Engineering Animations

 

 

Often, drivers involved in an accident will profess that each had their corresponding green light. Unless there isn a signal malfunction, both cannot be right. Sometimes there are clues to help determine who was at fault.

In the following case, the tractor trailer driver stated that he had the green left turn arrow. The oncoming SUV driver stated that he had the green light and the witness said that they received the green light about 5 seconds after the accident happened.

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iPhone Expert Witness

Apple’s Health App: Key to Forensic Analysis


Timothy R. Primrose, Mobile Forensic Analyst

Apple’s health application monitors and documents a user’s day to day activity in detail. Some data is collected by the iPhone, while other data can be collected from a synced Apple watch or input directly by the user. These datatypes include steps, body measurements, menstrual cycle tracking, hearing, heart rate, mindfulness, mobility, nutrition, respiratory, sleep, vitals, and other user input data such as blood glucose and inhaler usage.

From a forensic standpoint, you might not think that health data can help decipher the events that unfolded in a given situation; however, some of these datatypes can be utilized creatively to assist in bizarre scenarios. The hearing datatype proved useful in one of our recent cases.

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Boiling Water

The Value of Product Reviews


John R. Yannaccone, P.E., Senior Mechanical Engineer

A mother purchased a hand-held clothing steamer from an on-line retailer. Soon after starting to use it, the steamer expelled a significant amount of boiling water which landed on the pant leg of the clothing she was wearing. This boiling water soaked the upper portion of one pant leg and caused significant burns to her upper thigh. The woman reported she had the top properly on the steamer at the time of the incident, but the boiling water came out of both the spout and around the steamer lid. This steamer was designed to quickly heat water to the boiling point, creating steam, which would be expelled out the front of the steamer to eliminate wrinkles in clothing.

Prior to conducting an inspection of the subject steamer, an exemplar steamer was ordered to evaluate the design and to perform tests to determine potential causes of water being expelled from the steamer. When ordering the exemplar steamer, it was noted that there were a significant number of negative reviews of the product, reporting similar issues with boiling water being expelled during use. Similar product reviews were posted on other sites that sold the steamer. Some of these reviews included information on how the steamer was being used when the water was expelled and were useful to show how wide-spread the problem was.

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DNA Expert Witness

Modern DNA Applications: Who was the Driver?


Dr. Christian G. Westring, Ph.D., Forensic Geneticist

The advent of DNA testing for forensic science applications has revolutionized the breadth and scope of how investigators can successfully use modern DNA testing to help solve a wide variety of cases. While DNA evidence is usually not enough to solve a case on its own, DNA is generally regarded as the gold standard among forensic practitioners. From its first inception more than 30 years ago, modern DNA testing employing autosomal Short Tandem Repeat (STR) tests can retrieve DNA profiles from as a little as 4 or 5 skin cells left behind on a touched surface. This dramatic improvement in test sensitivity has made it possible for investigators to distinguish various individuals from multiple contributor (mixture) samples.

While more “traditional” criminal investigations will always be the norm (sex assaults, homicides, high-volume crime, etc.), new applications to forensic DNA testing continue to surface. Consider the following case scenario employing modern STR kits. A motor vehicle was involved in a single-car accident – likely as a result of excessive alcohol consumption. The occupants of the car exit the vehicle before law enforcement arrive at the scene. As each individual is questioned, it becomes unclear who was operating the vehicle at the time of the accident. Ultimately, the owner of the car is charged with DUI following a positive test for alcohol. Was the owner of the car the person operating the vehicle at the time of the accident?

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