Instant Photography

Instant photography was born 67 years ago and has ever since remained one of the few milestones of photography that still attracts customers to the day.  Even though technology has advanced a great deal, instant cameras still function with the same chemical reactions that were used in the first instant camera developed in 1947. In an instant camera, a colour film is enclosed in a light tight part of the camera. This plastic film consists of three light sensitive layers, sensitive to the colours blue, green and red. In between each of these layers there is a dye developer, which will later turn the photons into metallic silver. Two more very important layers, the light-sensitive layer and the image layer, are located just above the different light sensitive and dye layers. If you take a picture with an instant camera, light hits the light-sensitive layer (covered in silver particles) of the colour film and causes a chemical reaction. A reagent, a mix of opacifiers (light blockers), alkali and white pigment, then starts off the developing process of the picture. While the picture is being passed out of the camera the reagent is spread over the topmost layer, the light sensitive layer. The different chemicals in the reagent slowly make their way downwards through the different layers (light sensitive layers as well as dye layers). In the light sensitive layers, the photons are turned into metallic silver particles by the reagent. After all of the developer dye has been dissolved, the silver particles can move up to the image layer now that the colours are all fully developed. Which of the colours are developed depends on which of the three light sensitive layers has remained unexposed. At this point, the picture is fully developed but it cannot yet be seen. This last step, the reaction of the acid layer with the opacifiers, results in the opacifiers clearing up. Now, after only a couple of minutes, the picture can be discerned.

Current Affairs Journal: Sixth Entry

Just recently I have uncovered another misbelief about forensic sciences. I guess all of you, like me, thought that fingerprints are foolproof and that there is no chance that fingerprints can belong to more than one person? Well, at least half of that statement is wrong. Fingerprints can indeed only belong to one person and one person only. Even identical twins don’t have matching fingerprints. But in forensic sciences, using fingerprints as identification has been doubted and questioned recently. The reason for that is (even though fingerprinting is considered highly reliable) that the methods of comparing fingerprints is „lacking objective standards“.
When fingerprints are analysed  there are two  certain aspects which are observed to distinguish the prints: Friction ridge patterns and minutiae points. The main focus in a forensic analysis lies on the minutiae points. The three patterns that can be found in any fingerprint are loops, arches and whorls. With a rate of 60%, the loop is the most commonly found pattern of the three. Minutiae points are certain features of the ridges on your fingers. About 9 different minutiae points can be distinguished and among these, the most common ones a bifurcation, a short ridge or a ridge ending. 

Now according to these points, fingerprints are compared. In order to be able to match a fingerprint to another fingerprint, a certain number of minutiae points must be matched. And this is where the problem lies: There is no fixed number of matched minutiae points, which makes a match a valid match. How do we know that a match of 5 minutiae points is a “real” match? And if you have two people that share the same 5 minutiae points, how likely is it that something like that occurs?
 The decision is entirely up to the examiner! Experts often declare something a match with about 12 or 20 matched minutiae points. Still, like I already mentioned previously, most of the time the decision is up to the examiner or the individual standards of the different labs.

Also, there are some flaws to the system that searches for matching fingerprints. A false positive, a fingerprint match which turns about to be “false”, and a false negative can still create an invalid evidence. A study conducted by Bradford T. Ulery, R. Austin Hicklin, JoAnn Buscaglia and Maria Antonia Robert, though, showed that only about 0.1% of all the examined latent prints in their study turned out to be a false positive. False negatives ( a print which is said not to be a match but actually is) are much more common with a rate of 7.5%. Even though the rate for both false negatives and false positives is quite low the number of errors that could, or do occur, is still immense. 

Current Affairs Journal: Fifth Entry

If you take a closer look at science fiction TV shows, you will realize that the ways forensic processes or technologies are represented vary greatly. Some shows manage to represent forensic processes very accurately. Still, there are shows that paint a picture that creates completely unrealistic ideas and expectations about this field of work.
As an example, I would like to look into a scene from the BBC’s TV series “Sherlock”. In the last episode of the third season there is a scene which shows Sherlock’s urine being tested for drugs. The scene itself is very short and only consists of three short sequences: the urine sample being taken out of a cup, the sample being mixed with a chemical substance and it being analysed under a microscope. But can urine actually be tested for drugs like this? Is this actually possible or just something the writers of “Sherlock” came up with?

In order to detect illegal substances in any body fluid (let’s assume it is urine), two certain tests are performed: a presumptive test and a confirmatory test. The first type, the presumptive type, can be performed on-site already but it is usually performed in the laboratory. The aim of presumptive tests is to tell if there are any drugs in the questioned sample. Those tests only result in positive or negative results, though. They are unable to identify the specific drug that was found but only the class of drugs it should belong to. In addition, presumptive tests don’t always give clear results or results that can be misinterpreted which makes them unreliable. Only a confirmatory test is able to tell specifically what it is that was found in the sample. Usually the whole process of toxicology screening (examining the patient, presumptive & confirmatory analysis, comparing,…)usually takes between four and six weeks.

The many different types of presumptive tests span from ultraviolet spectrophotometry and microcrystalline tests to Colorimetric tests. Certain reagents in these colorimetric tests react with chemical components of the different drugs. A testing kit for a colorimetric test consists of a specialized paper that changes its colour when it gets in contact with a certain substance. If it turns one colour, the drug is present in the sample. If it turns another, it isn't. The colour it changes to varies because every drug causes a different chemical reaction.  Ultraviolet spectrophotometry is another procedure where the sample is treated with ultraviolet light and, according to the sample’s reaction, analysed and categorized.

Confirmatory Tests are performed either via Gas Chromatography/Mass Spectrometry (GC/MS) or just via Gas Chromatography or Mass Spectrometry. Each of these three processes tries to find out the substance’s chemical signature. The Mass Spectrometer vaporises the atoms that are analysed before they are turned into positive ions (by knocking out electrons). These ions are then accelerated, so they turn into beams, and deflected by a magnet. It depends on their masses on how strongly the ions are deflected e.g. a golf ball would be deflected more strongly than a snooker ball. The beams hit a detection plate and create a tiny electrical current. The more ions of a specific mass-to-charge-ratio, the greater the electrical current and the bigger the graph in the stick diagram becomes. 

The Gas Chromatography on the other hand works in a very different way. A vaporized sample is carried through a “column”. For the sample to be carried through the column (which looks more like a tube, really) you need a gas like nitrogen. The atoms in the sample are carried through the column at different speeds, which is why they separate. A detector then detects the different chemicals and are shown as peaks on a chart. The succession of the difference substances on the chart tells you what chemical it might be. So the difference between MS and GC is the following: while GC only tells you what it is that’s in the chemical, MS can tell you the masses and charges of the substances. This is the reason why those two types of confirmatory test are most often combined to a GC/MS test.

Now, if we look at the scene again (and look at footage that doesn’t show the drug testing) you can see a rather dazed and seemingly tired Sherlock. As a viewer of the show, the audience knows that Sherlock was addicted to heroin. This leads to the presumption that Sherlock might be high on heroin. If a forensic scientist would look at this situation, he or she would usually take an additional step before presumptive and confirmatory testing: analysing the behaviour of the person that has supposedly consumed drugs. Heroin causes a person to be "drowsy" which is why, if one were to observe Sherlock in the scene, his behaviour is accurate.

Now if you look at the scene again, you’ll notice that the three steps I mentioned above (“taking the sample, mixing it with chemical, analysing it under the microscope) don’t fit any of the above mentioned tests. But then again…I mentioned something about a microcrystalline test which I intentionally left unexplained. This test, also a presumptive test, consists of three simple steps. A chemical is put on a slide and mixed with a drop of the sample. The reaction of the substance with the chemical leads to the forming of crystals. The form of the crystals differs very much, though, because every drug has a different crystal pattern. The crystals are then analysed under a light microscope and according to those you can at least identify what class (e.g.narcotics, stimulants,..) the drug belongs to.

So the answer to this overly long post is….yes, the procedure shown in the episode of “Sherlock” is, or could, actually be a real forensic procedure. Well then, kudos to Mark Gatiss and Steven Moffat.

How to kill Hitler

This set of instructions will act as a helpful “how-to” guide for all of you people coming from the future to kill Hitler. It will explain all the necessary information you need to eliminate Hitler once and for all and help you change history for the better.

What you need:

1. A well-functioning time machine or a tardis
2. Knowledge about World War I and World War II
3. A great deal of determination

1.      Get your hands on one of the hopefully already existing time machines or tardises. If humanity hasn’t yet managed to build a time machine, simply go ahead and build one yourself.

2.      Make up your mind about which of the two options you prefer: Killing Hitler back in 1915 or killing him in 1933. If you decide to travel back to 1915, go straight to step three. If you choose 1933, skip the next three steps.

3.      Find out everything about Hitler’s time fighting in World War I.

4.      Travel back through time and space until you reach the year 1915. Become a soldier in World War I and get friends with Hitler.

5.      When an opportunity presents itself, shoot Hitler on the battlefield.

6.      In case you decided to travel back in time to 1933, think about whether you would prefer to plan Hitler’s assassination yourself or if you’d like to help someone else kill Hitler. If the latter is the case, go straight to step eleven.

7.      If you decided to stick to your own plan, find a way to become one of Hitler’s trusted advisers.

8.       Gain his trust. Then, think about which of the two options would be more likely to annihilate Hitler without any room for mistakes: a gun or a bomb.

9.      Make sure that there is absolutely nothing that could possibly go wrong with your plan.

10.  Then, shoot or blow up Hitler when he least expects it.

11.  If you decided to help someone kill Hitler, get in touch with a man called Karl Lutter.

12.  Join Lutter and the KDP.

13.  Find the people who betrayed Lutter and stopped him from killing Hitler. Now, kill them.

14.   If you successfully completed the prior step , Lutter’s assassination attempt will succeed and he’ll kill Hitler for you.

15.  Now that your mission is complete, hurry back to your time machine/tardis and get back home before anybody notices that you might have just changed the course of history for the better…or did the opposite.

Group Comment on Instructional (camera lucida)

Regarding Tim Hunkin’s set of instructions on how to make a camera lucida, we have to remark that they seem more confusing than helpful. There are no detailed explanations delivered on how to perform the different steps. In order to understand Hunkin’s instructions, specific knowledge is required, which makes this set of instructions suitable only for people with more advanced knowledge about how to construct a camera lucida. Above all, the construction of the wooden scaffold for the camera lucida remains a mystery to us, as there is not a single word mentioned in the instructions on how to build it. If you are not familiar with building something by yourself, this step might cause you serious problems. Apart from this lack of information, this set of instructions doesn’t  fulfill two more important aspects. The steps are neither numbered nor in a chronological order, which might cause errors during the process of building the camera. The font used in the set of instruction makes the instructions even more confusing because it is almost impossible to discern the unit of length. Also, at the beginning, the list of needed materials and tools is missing.The only positive aspect we found is the use of pictures in this instructional text, as they make it easier to follow the instructions.

Current Affairs Journal: Fourth Entry

To start off I’d like to give you guys a proper definition of forensic sciences. According to the Staffordshire University forensic sciences can be described as sciences that were solely created for “law-related purposes”. It is supposed to provide “impartial scientific evidence” that can then be used in court to help investigate a case. Forensic sciences, as the name already suggests, consists of many different sub branches. Some of these are “Forensic Chemistry”, “Forensic Biology”, “Forensic Pathology” but also branches that draw from geology/psychology/ such as “Forensic Botany”. For those who have not yet understood, Forensic Sciences is what you see happening at crime scenes or labs in crime TV shows.

But when exactly did people decide that they needed SOMETHING, anything really, that could help them solve crimes? When I talk about crimes, I don’t necessarily mean murder or blackmail but everything that is against the law and needs to be investigated with the use of forensic sciences.
An exact point for the birth of forensic sciences is very difficult to find. Still, the first evidence of the use of fingerprints can already be found 700 BC, and even earlier. These fingerprints were used on clay tables to make “business transactions”, which can most probably be compared to a person’s signature or a receipt today.

Only in the 19^th century (70s and 80s)  fingerprints started to be used in the investigation of murder. The first two people that tried to use fingerprints to identify people were Sir Edward Richard Henry and Sir Francis Galton. Galton was one of the first people to observe fingerprints and consider them as a mean of identification in 1888. He only published his book on fingerprints four years later (1892), though. Sir Edward Henry developed his own classifying system in 1896 and it became the standard for fingerprinting techniques all over the world and has been used by detectives working for Scotland yard since 1901.

Now let’s go back in time a few years and look at something that actually happened before Henry and Galton came up with their brainchild (I didn’t want to confuse you by mentioning it in between the fingerprinting history). Around 1813 Mathiew Orfila published a book on toxicology (first book on toxicology ever!). He is considered „the father of toxicology“. But…what is toxicology? Bear with me. I’ll make you understand what a big deal the birth of toxicology actually is. Toxicology is a study that tries to find out how poisonous substances affect the human body. Toxicologists try to find out how the body is affected by poison, how it reacts, what symptoms are caused by poisoning and how a poison can be detected. Therefore, Forensic Toxicology deals with the detection of such substances (can be poison, drugs, chemical substances,…) in body fluids or hair (CAREFUL: Toxicology is not to be mistaken with drug analysis!).  Without Orfila we would be unable to detect any kind of poison or drug in blood, urine, or hair. Without his wit that helped prove that a lady killed her husband with arsenic, who knows how forensic sciences might have developed.

If we take another big step from where we are now in time and travel to the 1830s we will discover that a man called Henry Goddard made a very important discovery. He was the first person to compare different bullets in order to solve a crime. At this point in time, people only focused on visible flaws or indents on the bullet. But in 1920 Calvin Goddard invented a comparison microscope that was able to identify bullets and match them with their respective shell casings. In the 1970s a method to discover gunshot residue and therefore identify the person who fired a bullet was invented. I think it is quite safe to say that the geniuses Calvin and Henry Goddard founded “ballistics”.

While Calvin and Henry Goddard laid the foundation of ballistics, a man called Edmond Locard also managed to do a revolutionary thing. He was the first person to ever establish a police crime laboratory in Lyon, France in 1910.

One of the next milestones in forensic sciences was the discovery of DNA profiling. The person responsible for this success was Sir Alec Jeffreys. With the help of DNA profiling people can be identified by looking at certain sequences of their genes. The DNA of every person is unique (apart from the DNA of identical twins) and therefore their DNA can be compared to the DNA found in gathered evidence. In 1985 DNA profiling was first used in the UK and two years later it was first used in a criminal court in the United States.

In the 20th century forensic sciences really started to “flourish”. In the mid-1900s different tests to analyse body fluids (blood, saliva, semen) were developed  as well as psychological profiling techniques in the 80s. Also, the very first National Criminal DNA Database was established in London.

Well then, now you know a little more about forensic sciences. Even though there is much more to talk about concerning the entire history and development of these sciences this is enough information to give you an overview. It is more than enough to make you understand how long people have already worked on the development and improvement of forensic sciences until today.