The Gist of Science Reporter: October 2015


The Gist of Science Reporter: October 2015


Pollens to Catch Criminals

Palynology was used as one of the major tools in war crime investigations in Bosnia. In July 1995, civilians were massacred and their bodies were buried in seven mass graves, following the fall of Srebrenica. Three months later the bodies were exhumed and transported to a number of new burial sites to hide the evidence of massacre and deflect the blame. However, palynological investigations clearly showed that the pollen and spores from the original mass graves had been transferred along with the bodies to the secondary burial sites.

During the 1960s and 1970s, a noted Swiss criminalist, Max Frei, often used pollen as a forensic tool to link suspects to events or to crime scenes (Palenik, 1982). In a well-known case, a suspect claimed that his pistol could not have been used to commit a recent murder because it had not been removed from its storage box in months. However, Dr. Frei proved the suspect was lying because grease on the pistol contained alder and birch pollen, both of which were pollinating when the murder occurred, not when the suspect claimed he had last cleaned the pistol and put it away.

In a rape case Horrocks and Walsh (1999) compared the pollen collected from the rape victim’s clothing and the suspects clothing with soil samples taken from the alleged crime scene and the alibi scene. The two scenes were only 7 meters apart but could be differentiated on the basis of pollen. The rape victim’s clothing and the suspects clothing showed very close correlation with each other and the crime scene in the amounts of pollen types present. This supported strongly the presence of the suspect at the scene of crime.

Forensic botany is the study of plants and plant remains and using the results to solve crime cases. This includes the analysis of wood, leaves, twigs, flowering tops, fruit, seeds, plant hair, pollen and spores. Pollen and spores are minute, light, microscopic evidential material, carried away unknowingly by criminals from the crime scene. This helps in linking a suspect with a unique crime scene or geographical region. The study of pollen and spores is called forensic palynology, Greek meaning “the study of scattered dust”. Experts in forensic pollen analysis are called palynologists. They take into account the growing seasons of pollen and spores and their geographical specificity making them beneficial in linking a suspect, victim or object to a particular crime scene.

Characteristics of Pollen

Pollen is the male sex cell produced within anthers in flowering plants or cone- bearing plants (conifers). Pollen grains are so small (avg. 20-60 urn) that they cannot individually be seen by naked eye. They have the property to stick to any surface and object. Pollens from the crime scene stick unknowingly to nostrils, ears, body, hair, cloth and shoes of criminals. Dallas Mildenhall, a senior palynologist from New Zealand, is of the opinion that, normal washing using domestic detergent will always wash some grains but sufficient pollen grains still remain embedded in the cloth to relate a criminal with the crime scene. Pollens are extremely resistant to physical and biological decomposition.

Each pollen grain is covered with a wall made of two layers. The outer wall is called exine, while the inner one is called intine. The exine is relatively thick, composed of cellulose that may be smooth or may have a variety of ornamentation. The exine is not continuous but has a few apertures. The exine is made up of a special complex chemical substance known as sporopollenin, which makes the pollens resistant to chemical destruction and helps them stay preserved at the crime scene for longer periods of time.

Since plants grow almost everywhere and their pollen are tiny, they have morphological diversity which allows many of them to be identified back to their parent plants. Most plants produce pollens in abundance that are dispersed by air. They mostly fall within 2 km of the source and in many cases within 100 meters. Certain plants disperse their pollen merely within a few meters. A pollen finger print is the number and type of pollen grains found in a geographic area at a particular month of a year.

What are the various functions that pollens perform as an important evidential material in solving criminal cases? There are many, such as,

1. To connect a suspect with a crime scene.
2. To connect an object left at the crime scene with the suspect.
3. To prove or disprove statements by the suspect regarding a crime.
4. To ascertain the geographic origin or location of narcotic drug-producing plants (e.g. cocaine, cannabis, opium, etc.) and their probable route of transportation.
5. To establish the purity of commercial honey said to have been made from the nectar of specific plants and produced in a specific geographical location.
6. Domestic pets or animals stolen or lost or associated with the crime scene may be traced to their original owner through the attached pollens in their hair.

Regular watchers of the investigative serial CID will know that after every crime the investigators painstakingly collect evidence from the scene of crime. Now, what are the types of evidential material a forensic palynologist looks for while investigating a crime? A forensic palynologist collects

1. Sample of soil and dust from the crime scene.
2. Sample of soil and dust from the alibi scene.
3. Sample of soil and dirt/ dust from clothing, hair and shoes of a victim for linking victim with the location where the crime occurred.
4. Sample of soil and dirt/dust from clothing, hair and shoes of suspect, thought to be associated with the crime.
5. Mud/ dirt/ soil of vehicle thought to be used in crime.
6. Sample of pollen from nostrils, ears of victim or suspect.
7. Scrapings from finger nails of victim or suspect.

Analysis of Samples

Before taking any exhibit for analysis, it is ensured that all glass-ware and tools are pollen free. For that a blank test is carried out as contaminated samples are of minimal evidential value. No forensic expert wants to waste his valuable time in analyzing contaminated samples.

The suspect’s and victim’s clothing, soil and mud of shoes are excellent traps for pollen and spores. The cloths/soil/mud scrapings of shoes are treated separately with 70% of ethyl alcohol. This process loosens the trapped pollen. Pollen in the wind is trapped in the human hair, as oil and hair lotions applied make the hair sticky. Hair of the suspect/ victim is carefully washed with detergent and distilled water. The water washings are collected and kept in a closed container after adding a small amount of alcohol to avoid growth of microbes.

Forensic Palynology in India

Forensic palynology has been used in crime detection since the last fifty years but is largely ignored especially in the developing world. Some countries have not recognized palynology-based valuable evidence in the court of law. New Zealand is the first country using pollen as evidence routinely in solving civil and criminal matters.

In India, forensic palynology has not received much attention till today. If proper training is given to forensic experts in pollen collection, storage and analysis, it will help in solving important cases like murder and rape. Courses in forensic palynology offered by forensic science institutes/ colleges in India could provide opportunity to students, forensic experts and law enforcement officers to learn more about the technique.

Making Buildings Earthquake Resistant is Good Economics

Buildings turn killers influenced by earthquakes. But this need not be the case always. The destruction to loss of life and property can be reduced to a large extent with intelligent design modifications to buildings. The idea of having earthquake-proof buildings may not be practically feasible, but’ earthquake resistance’ is achievable.

Whenever a major quake rocks our neighbourhood questions are asked ‘when will science be able to predict and prevent earthquakes?’ But little attention is given to ‘what is achievable’ - making our houses and buildings such that they can withstand quakes.

Making houses quake resistant should not be viewed as an isolated issue of science. It must be considered an essential ingredient of economics too. If this aspect is overlooked, all development is reduced to nought in a matter of minutes.

Reports from the Nepal disaster speak for themselves. Apart from the loss of life there has been colossal damage to property and infrastructure. A fraction of this amount if spent on design safety while constructing could have saved much of what has been lost.

In our country too, there was much talk of making houses quake resistant after the quakes in Gujarat and the Himalayan region. However, very recently, Delhi’s three municipal corporations accepted before the court that 80% of Delhi’s houses are unsafe for a tremor of intensity that rattled Nepal.

Minimizing Quake Disasters

Earth scientists say that the solid looking land on which we reside is like a layer of solid cream floating over boiled and cooled milk in a pot. Our Earth being a spherical liquid body of molten materials, there are lumps of solid rocks floating over it. Due to convective activity in the fluid beneath, these lumps are always on the move, pressing against or separating away from each other.

This sudden and vast release of energy creates shock waves in the land mass around the point of realignment. These waves can travel hundreds of miles on the land surface. The waves created are of two types - those moving the land in up-and-down position and those shaking the ground side ways. It is the second kind that causes most of the destruction, because buildings generally bear their movements in vertical direction but are unable to bear the horizontal load exerted by shock waves. Earthquake-resistant technologies for building rest on this understanding of science.

Quake-resistant Measures

In applying the various quake resistant options one must have a fair idea of the scale and economy of the structure being considered for safety. We can have three broad categories:

(i) Landmark structures involving very high capital spending,
(ii) Average residential structures and
(iii) Low cost dwelling units based on local materials.

Both ancient and modern technologies are now being applied to make landmark buildings quake safe. This includes skyscrapers like Burj Dubai and Taipei101, the Transamerica Pyramid, San Francisco City Hall, prominent governmental centres, hospitals, fire brigades, etc.

The buildings are mostly composed of bricks and mortar. When a shock wave comes, it jolts the building making it shake left-right. This may cause cracks and if the sway is beyond the centre of gravity of the building, it simply falls down. Therefore, we must minimize the lateral shift of the building. For this, two prominent methods are being employed by engineers:

l. Base isolation techniques and
2. Vibration damping mechanisms.

In the base isolation method, as the name suggests, the building is separated from its foundations through ball bearings, springs or padded cylinders. When quake shock waves move the earth’s surface sideways the foundation of the building also moves with it. Since the building is separated through bearings, it remains as it is and the horizontal swing is minimized. However, because of structural and material constraints there could still be some swing transmitted to the building.

When the building shakes because of a quake or even a hurricane, the dampers absorb the energy to counteract the motion. It can move 5 feet in any direction. The mass is so heavy that it is not possible to lift by the heaviest crane ever built. So it was assembled and constructed on-site. Such techniques, however are highly capital intensive and can be considered only for special landmark buildings. Testing an earthquake-resistant house takes a big earthquake simulator called a shake table. The facility uses computer-controlled hydraulic pistons to move the platform back and forth in a pattern selected by the engineers, so it can replicate specific earthquakes.

Using video records and data from transducers, it is possible to interpret the dynamic behaviour of the specimen. Earthquake shaking tables are used extensively in seismic research, as they provide the means to excite structures in such a way that they are subjected to conditions representative of true earthquake ground motions. India has around 11 such facilities, including the one at IIT Roorkee, Uttarakhand.

Coming to the average residential structures, one must first have a detailed survey of the place where structural projects are going to start. The seismic activity of the site has to be assessed. The first help comes from the government bodies. In USA, for example, ‘National Seismic Hazard Maps’ are placed in public domain by the U.s. Geological Survey (USGS). These maps give a fair idea of the seismic sensitivity of the particular place. This enables an educated guess of the place in terms of the recurrence of the highest quake shocks likely to be experienced in future. On this basis the entire coast of California is an area of high hazard.

In India too the country is divided into five seismic zones. The Himalayan belt is the most vulnerable. The National Capital Region (CR) comes under zone-IV. Building design is also important. To have the best suited design for a particular site and the type of project perceived there are various guidelines available. International Building Code is the one that is followed by US designers and engineers. India also has a National Building Code. There are guidelines by the Bureau of Indian Standards (BIS) for making earthquake resistant and economically viable designs.

Engineers and architects must adhere to stricter norms in seismically red zones. Irregular and asymmetrical designs need to be avoided. These include L- or T -shaped buildings. They are susceptible to torsion, or twisting about their longitudinal axes. Ornamentations like cornices or cantilever projections must be avoided as earthquakes easily dislodge them from the main building to go crashing on the ground.

The Transamerica Pyramid in San Francisco is an example of strengthening through X-bracing technique. It is 260 meters high. Its truss system supports both vertical and horizontal loading. It is particularly resistant to torsional forces generated by quakes. Since its inception in 1972 it has successfully faced many big quakes. An earthquake of 7.1 magnitude in 1989 made the top story of the pyramid to sway by more than 30 centimeters from side to side, yet it stayed as it is.

Traditional Dwelling Units

The national and international building codes, however, appear to be inapplicable and ineffective in case of traditional houses made using available raw materials in the various geographical locations. The situation needs to be viewed with an entirely new vision. In Peru, an innovator has strengthened the cheap sun-dried brick walls by reinforcing them with strong plastic mesh installed under plaster. In India, locally built walls have been reinforced with bamboo - a cheap and effective method. In Indonesia ground-motion dampers have been designed by filling old tyres with sand bags. May be it is not as strong as high-tech materials, but then it is what is affordable and practicable. In Northern Pakistan, high resilience straw is easily available and so a Californian engineer working there has mixed it with the mud used as binding material in making building walls of stone. Building materials, therefore, must be chosen not only on the basis of their physical strength but also their availability and cost factor.

Technology apart, life and property can be saved against the unpredictable cruelty of quakes primarily by remembering the phrase of wisdom: ‘Prevention is better than cure’.

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