asalamon's blog

On October 22, a headless macaque (donated by Harvard Univerity after its natural death) was placed on a piece of slate in Dr. Pérez’s Taphonomy Lab at University of Massachusetts, Amherst.  When the macaque was placed in the lab, it was frozen and had a sagittal incision in its abdomen.  Weekly visits were made to the lab by the 2018 Forensic: Myth and Reality Class.  On November 26, the macaque was removed from the slate and placed directly on the ground.  Motion sensitive infrared cameras captured any movement around the body during its decomposition.  At the conclusion of the class, Kara Koziol continued to make biweekly visits to the lab to record visible changes to the macaque. 

During extraction experiments, two compounds can be separated from each other by utilizing their solubility in two immiscible solvents.  The solvents are separated from each other because they each have their own density.  Therefore, the one with the larger density, would be the bottom layer.  Acid-base extraction utilizes acid-base reactions to alter the solubility of the acidic or basic compounds in the solvent in order to separate them.  During this lab, water is used as the aqueous solvent for the unknown carboxylic acid.  Tert-butyl methyl ether (TBME) was the either used that would contain the neutral compound.  The unknown carboxylic acid is highly soluble in the ether layer, therefore a base, NaHCO3,was added to the carboxylic acid to form a carboxylate which is water soluble and ether insoluble.  This separates with unknown neutral organic compound to the either layer as they both have low polarity and the unknown carboxylate which are both polar.  Because the water layer is denser, it would be found in the bottom of the test tube with the two solutions.  With the two layers determined, they can be separated and purified.  For the organic layer, some residual water can be found in the layer so NaCl is used to backwash the solution and remove any aqueous waste.  In addition, a drying agent, CaCl2, removes the last of the water.  In the aqueous layer containing the unknown carboxylate, HCl is used to turn the basic layer back into the carboxylic acid.  Both solutions utilize recrystallization to purify them. 

In October of 2018, a frozen, headless macaque was placed in the UMass Taphonomy Lab and the taphonomic process of its decomposition was studied  Motion activated infrared cameras captured images of any organisms visiting the macaque throughout the process.  In addition, visits were made biweekly to record the progression of the decomposition.  Due to the time of year and weather patterns, the process of decomposition was unique in that insect activity was subsequent to animal activity.  Also, the wide variety of animals which fed the macaque cooperated in sharing the macaque as a food source.

Observations

• In all the images
  • letters are of different sizes
  • the letters are in different locations
• In images A and B
  • the scope of the image is different, the left panel is from a closer perspective using google earth
  • the right figure uses pink arrows and the left does not use arrows
• In image c
  • the light is different
  • the scope of the image is different as the sidewalk is visible in the left image
  • the angle of the picture is different as the library is in different positions of each picture
  • the quaility of the image is less in the right image
  • there is tent/event in the right image

Alternative catagories

• formatting issues
• phography method
• scaling of images
• timing of images

Factors:

• lack of scaling
• time of day
• type of camera
• perspective/location of camera
• direction to taking the image

    Darwin travelled the world exploring variation within and between species.  Despite all the evidence of variation within other species existing for a specific purpose, he still wrote off the variation of human skin color as having no evolutionary significance.  This is not the case.  Humans evolved around the equator where UV light was the strongest.  Particularly, the equator gets the highest intensity of UVB lighting which is a key catalyst for the vitamin B.  Melanin was also utilized as a sunscreen to protect DNA from the damage of UV light while giving the its darker pigmentation.  As humans traveled away from equator, they adapted to the environment with less UV exposure and evolved to have lighter pigmentation in their skin. Many different groups of humans travelled away from the equator at different points of time, even the Neanderthals experienced this change in skin pigmentation.  With humans moving all over the world, people with darker skin pigmentation are now living in an environment they are not suited for and have resulting heath issues and vice versa for those of lighter skin pigmentation.  

In order to understand the human body, model organisms are used as replacements for humans in experiments.  These organisms are chosen for a variety of factors.  First, they must be genetically similar to humans or have enough similarities in the area of study.  Next, they need to have a short generation span so the effects of the study can be observed through the entire lifespan and into furture generations.  During their lifespan, model organisms need to produce a large number of progenies to increase the sample size of the population.  The gene crosses must be controlled as well and they must be suited to live in lab settings.  Finally, the organisms need to have an accumulated body of knowledge.

There are a variety of model organisms used in reasearch.  The type of organism chosen is determined based on the focus of the research.  Some common types of model organisms include E. coli and saccharomysoes.    E. coli is a species of bacteria.  Despite being a single-celled prokaryote, they have significant value to scientific studies.  They are especially useful in studying cell respiration.  Saccharomyoes or yeast is another type of organims used in laboratory settings.  Scientists use this model organims to study processes like protien scretion, control of the cell cycle, and cell differentiation.  

In order to understand the human body, model organisms are used as replacements for humans in experiments.  These organisms are chosen for a variety of factors.  First, they must be genetically similar to humans or have enough similarities in the area of study.  Next, they need to have a short generation span so the effects of the study can be observed through the entire lifespan and into furture generations.  During their lifespan, model organisms need to produce a large number of progenies to increase the sample size of the population.  The gene crosses must be controlled as well and they must be suited to live in lab settings.  Finally, the organisms need to have an accumulated body of knowledge.  One example of a model organism if E. coli which are useful for the study of cell respiration. 

As a species, humans have recently become vunerable to allergies.  Even if your parents are asked, they will say allergies were not as much of a concern as they were not.  One theory explaining the prevelence of allergies in humans, particularly those of first world countries involves helminth infections.  When an antigen enters the human body, the antigen bind to T cells which then stimulate B cells.  B cells differentiate to form antibodies like IGF which binds to other cells of the immune system and arm them against the antigen.  IGF is an important form of antibody because it is key to the fighting of helminth infections.  The armed cell can then react to antigens like cats and dust that do not pose of risk to the health of the individual.  In populations with high levels of helminth infections, the IGE levels are very high compared to populations lacking helminth infections and none of the individuals have allergies.  It is thought that the helminth infections keep the IGE "busy" so it does not have time to react to antigens that are not dangerous (those causign allergic reactions).

During the lab, melting points of both the phthalic acid and unknown 1 were taken before and after recrystallization.  Before recrystallization, phthalic acid had a melting point of 200-203°C.  The range being greater than 2°C difference is indicative of impurities in the sample. After recrystallization, the melting point of phthalic acid was determined to be 207-208°C.  The increase in temperature as well as the narrowing range is consistent with purifying the solvent.  The presence of impurities in a compound will cause a melting point depression.  This depression will be lower than the actual range for the pure compound and at a higher range of values.  Both these trends are shown with the data.  The melting point of phthalic acid is known to be 207°C (National Center for Biotechnology Information).  Due to this information and the trends of melting points before and after recrystallization, the phthalic acid had been successfully purified during the recrystallization.  Before being purified, unknown 1 had a melting point of 105-110°C.  After recrystallization, the new melting point was 124-125°C.  Like the melting point changes seen in phthalic acid, the impure sample of unknown 1 had a wide melting point range, greater than 2°C, which is indicative of an impure compound.  The new melting range is also larger, showing the melting point depression which occurring when impurities are found with a compound.  Like with phthalic acid, the unknown 1 was successfully purified based on the melting point values.