It is clear from our results that decreasing the solar constant redistributes and reduces warming, yet it does not do so in a spatially uniform way. Moreover, it redistributes precipitation. The top row in Figure 3 shows the amount of temperature and precipitation increase we will experience, from present, based upon RCP4.5. The middle row represents the amount of temperature and precipitation change experienced with the implementation of the G3 scenario. The bottom row shows the amount of warming and precipitation we will not experience if geoengineering is implemented.

As shown in Figure 3, no mitigation, with the assumed RCP4.5 forcing, will result in warmer temperatures. These temperature changes are greatest at the poles. Precipitation will increase in the Tropical Pacific and decrease in certain semi-arid regions of the globe. The 2013 IPCC showed that using geoengineering to counteract atmospheric warming, caused by increased CO2, will change the atmospheric vertical heating profile. This leads to less cooling in the tropopause, a boundary between the troposphere and the stratosphere. Since precipitation and temperature share a direct relationship, the decrease in cooling from geoengineering corresponds to a decrease in rainfall (10). This decrease in temperature and precipitation is manifested in the spatial patterns represented by the difference between the RCP4.5 and G3 scenarios. Even though temperature and precipitation are predicted to redistribute globally with the G3 scenario, temperature and precipitation changes are more severe without mitigation. A spatial redistribution of temperature and precipitation can impact a region politically, biologically, and socioeconomically. Geoengineering as a form of mitigation has the potential to lessen climate change if the associated consequences are managed.

It is important to note that global climate models exhibit some biases and are not entirely consistent with historical records. The models consistently produce precipitation results that are generally too wet overall (9, 11). Models also tend to reduce precipitation in dry regions and increase precipitation in damp regions (5). Many models do not accurately represent the Tropical Pacific. Models tend to depict this region with a two-band-like pattern of precipitation, as shown in the right column of Figure 3. This region should be depicted with a single band of increased precipitation rather than two. This bias is represented in our results shown in the right column of Figure 3. These considerations are particularly relevant to the problem of geoengineering because the projected changes look like the biases.

Although the modeled responses are not perfect, global climate models are the best option for exploring the real potential outcomes of deliberately changing insolation because they do not pose actual risks to humans and ecosystems like field experiments might. Moreover, because we have a good idea of what model biases exist, we minimize the effect of the model biases by using multiple models and by looking at overall trends rather than specific spatial patterns. The work here helps to explore possible outcomes in regard to temperature and precipitation, with or without geoengineering, and document the potential benefits of it.

The authors demonstrated that the more contrast there was between a letter and its background, the more commonly the letters were identified at lower levels of light. The authors also determined how much effect age has on contrast sensitivity.

The authors hypothesized that every subject would be able to identify at least the first five letters (20% saturation) by the time all five candles were lit (50 lux). The first five letters had the most contrast with the white printer paper background, so we predicted that these letters would be most commonly correctly identified because they are the darkest. On the other hand, it was predicted that very few, if any, subjects would be able to see the last five letters (3% saturation) at any of the levels of light. The prediction that all of the subjects would identify at least the first five letters with 50 lux of light was correct. In addition, 96% of the subjects identified more than the first five letters. The number of letters identified with all five lights on ranged from 4 to all 25 letters.

We hypothesized that, in general, the younger subjects would have better contrast sensitivity and would identify the letters at the lower saturation levels better, since their eyes are younger and stronger. On average, the subjects who were under 40 identified 18 letters by the fifth light. On average, the subjects who were over 40 identified 13 letters. Three subjects, all in the younger age group, were the only individuals to identify any of the letters presented at the lowest contrast (3% saturation). Other contrast sensitivity experiments that have been conducted in regular room light levels and did not involve different levels of low light found a decline in contrast sensitivity as a person gets older (10). Studies have shown significant differences in the performance levels of a younger age group (age 20-30 years) in comparison with an older age group (age 50-87 years) (11).

Many subjects mentioned that they could see the letters easier when they were not looking at them directly. This is because rod cells are missing at the very center of the human retina and instead, extend to the periphery of the retina (9).

This experiment included several systematic errors. For example, the exact amount of time each subject took at each interval to study the letters varied, including the length of the interval in complete darkness. Also, the amount of time each subject was in the bright light of the kitchen varied. One potential measurement error was that the light meter was not sensitive enough to accurately measure the light intensity at the subjects’ seat, so the measurement of the illumination (10-50 lux) was taken 10 cm away from the light sources.

Errors that could have affected the experiment are that the exact eye sight and vision corrections for each subject varied and the size of the subject’s shadow cast by the light onto the table where the letter card was may have made some of the letters harder to see or appear different from one person to another. Some subjects were more reluctant to guess or change their guesses because they wanted to name the correct letter and not make errors.

Future experiments based off of this study could include the use of different colors of letters. In this case, yellow would have less contrast with the white background than a dark blue would have. Different tests could be done with a black background for different contrasts of gray to black letters. This data would be compared to the data from a white background test.

The hypothesis was that if the viscosity of a fluid increased, then the surface tension would increase because the molecules are more tightly bonded. It was based on the idea that when the cohesion of the molecules in a fluid is higher, the viscosity of the substance will increase and will lead to the increase of surface tension because the water molecules on the surface show more cohesion. Contrary to these predictions, the results from the flour surface tension experiment showed that water, which had the least viscosity, had higher or about the same surface tension as most of the other solutions with a higher viscosity (Figure 2B). Results from the agar surface tension experiment showed that water, which had the lowest viscosity, had about the same surface tension as all of the other higher viscosity solutions (Figure 2A). These results reject the hypothesis, since surface tension did not increase as the viscosity increased.

Viscosity can be understood as the effect of different layers of the fluid exerting shearing force on each other, or on other surfaces, as they move against each other (1). In other words, the friction between neighboring particles in a fluid causes the viscosity. Viscosity results from the strength of the attraction between the particles of the liquid (5). Surface tension can be understood as a downward net attraction exerted on the surface of a fluid (1). Hydrogen bonding causes molecules away from the surface to engage in a tug of war with their neighbors on every side and thus undergo no net attraction. However, since molecules are not present above the surface of the fluid, the molecules located on the surface are pulled inward (2). This creates some internal pressure and forces liquid surfaces to contract to the minimal area (6).

Intermolecular forces play a role in viscosity, because stronger attractions between molecules cause them to resist flow more strongly. Molecule size is also an important factor in viscosity because the attraction of intermolecular forces is stronger, so that they cause more friction. Surface tension is also a result of intermolecular forces (7). If both are related to intermolecular forces, why are they not related to each other?

Flour contains a high proportion of starches, which contain a large number of glucose molecules. The chemical formula for glucose is C₆H₁₂O₆ which is larger in size than water molecules (H₂O) since it has more chemical components. Therefore, starch, which is the major molecule in flour, is larger than a water molecule. Agar is a gelatinous substance. Gelatin is a mixture of peptides and proteins. Peptides and proteins are made of amino acids which have the chemical formula RCH(NH₂)COOH (8). R represents the rest of the amino acid structure which is different for each amino acid (8). Amino acids are larger than water molecules because they contain more chemical components. Therefore, peptides and proteins are larger than water molecules, and thus gelatin, and agar molecules are larger than water molecules. The large molecules in flour and agar solutions have a lot of polar functional groups, which means that they have a lot of atoms which are slightly charged and attracted to each other. The results show that solutions with higher concentrations of agar and flour, which had higher viscosities than water, had practically the same surface tensions as water. Therefore, the intermolecular bonding of water, which causes surface tension via hydrogen bonding interaction was not increased when viscosity increased.

The viscosity increases when the concentration of large, charged molecules increases, which causes increased intermolecular attractions that result in resistance to flow. The hypothesis was proven wrong because the cohesion measured in the viscosity test was not the same cohesion that caused surface tension. Essentially, the viscosity test measured the resistance to flow caused by interactions between flour or agar molecules, while the cohesion responsible for surface tension was dictated by the intermolecular attraction of water. Surface tension was only caused by the intermolecular attraction of water molecules (hydrogen bonding) because adding other compounds to water did not change the surface tension (Figure 2).

The solution with the lowest concentration of flour (0.22 g/mL) had lower surface tension than water and other flour concentrations. It could be speculated that a small concentration of flour might affect the fluid’s surface tension. Another explanation could be that an experimental error occurred during the mixing process or the surface tension measurement. An improvement to my experiment could be to increase the number of experiments to verify the conclusion.

This experiment explained one of the fundamental features of water, the most important and common substance on our planet. Whenever surface tension is taken into account, only the hydrogen bonds of the water molecules should be considered. Another significance of the experiment is that it shows that what might be taken for granted is not always fact. This study contributes to our fundamental understanding of water, which is important to life and research. Any knowledge gained about its function is vital for our understanding of life and the forward march of fundamental and applied research.A future study could be conducted to determine whether temperature affects the relationship between surface tension and viscosity. A possible hypothesis is that a lower temperature would affect the interactions between the large molecules and water because the molecules have less kinetic energy.

Results show that surface tension did not increase when viscosity increased. The hypothesis was that if the viscosity of a fluid increased, then the surface tension would increase because the molecules were more tightly bonded. It was proven wrong. The idea behind the hypothesis was that the increase in viscosity, due to increased cohesion of the molecules in the fluid, would also increase the surface tension. The surface tension did not increase because surface tension is affected by the intermolecular attraction of water molecules (hydrogen bonding); however, the viscosity of a fluid is influenced more by the friction caused by the interactions between large charged molecules. The intermolecular hydrogen bonding of water molecules was apparently not changed when viscosity increased in this experiment.

For decades, the use of hand-sutured CABG has been widely successful. However, with the increased interest in reducing surgery time to potentially reduce the risks associated with longer surgeries, a new interest in staple anastomosis devices has emerged (10). The original problem between the staple and suture was that surgeons and medical researchers were not fully clear on which method provides a higher flow rate. Moreover, while increased benefits are recognized from new medical devices related to heart surgeries, results of a clinical study indicated that three patents who had undergone stapling had to be converted to hand-sutured anastomoses due to “inadequate blood flow” (10). As such, it appears that additional research on comparing stapling and suturing anastomoses is warranted.

According to the results of this study, the sutured artery appears to have had the higher flow rate between the two graft types measured. This research shows that suturing should continue being utilized in coronary bypass grafting anastomosis because it appears to have a higher flow rate as demonstrated by Poiseuille’s Law. According to Poiseuille’s Law, even a minimal reduction in the artery’s radius could make a big impact on the blood flow rate, with all other factors remaining constant (Equation 1). Also, suturing can continue helping many coronary artery disease patients to have a higher blood flow rate in their coronary artery after surgeries. Coronary heart disease is a worldwide disease, so this research can help people worldwide to better understand this disease, how to cure it, and how to still have a good flow rate after it is threated. Moreover, with the results of this study, it is evident that additional research may be needed to further investigate the full impact of automated suturing (also known as arterial stapling) while maintaining a quality blood flow rate for the patients.

There were some limitations with this experiment, including inaccuracies in measuring tools, along with some differences between the artificial heart used and an actual procedure on a human. Inaccuracies in measuring tools included a need for a more precise gauge that can measure PSI. A more accurate gauge with a sensitivity of 0.1 PSI could have helped obtain more precise measurements. Additionally, the Lego® NXTTM arm had to be put at -120° to begin or else it wouldn’t have provided sufficient starting pumping power, and as a result, wouldn’t pump enough blood for circulation.

Figure 8

Figure 8: A simulated clear coronary artery (A) and low as well as medium occlusion levels (B & C) in the Lego® NXTTM artificial heart.

While the model used in this study included a simulation of a biological heart, the model is still valid when it comes to the demonstration of the impact of differences in the occlusion level on flow rate along with a novel application of Poiseuille’s Law. However, there were still some differences between the experiment on the artificial heart used and an actual procedure on a human. These differences include the experimental artery/anastomosis replacement in the device and type of staple. Specifically, switching the arteries was difficult due to short blood loss, so the heart reservoir had to be refilled several times during the experiments (similar to blood transfusion in real operations). Another limitation is that the staples used in this experiment were the ones for skin, rather than those used for actual coronary anastomosis; however, the ratio of coronary-radius to staple size was maintained. Using the skin stapler distorted the artery’s shape even more than it would have with actual coronary stapler, but due to the very high price of the coronary stapling device, its use was not feasible. As a result, it caused a slightly lower flow rate, and the stapling reported here most likely shows more blockage than a real coronary stapling device would. However, coronary stapling still needs technical improvements and more scientific research. It has been documented that suturing takes much more time, stress, and skill compared to stapling. A surgeon can press the handle of the coronary stapling device and the artery is connected; however, if it isn’t stapled correctly, additional procedures will be required to fix it (10). In general, the aim is to reduce time and complications for the patient, while attempting to save their life. Additional research is recommended to learn more about how to improve the staple anastomosis in terms of improving blood flow rate in the grafted artery. Future research can be done using more precise digital gauges, more accurate and delicate staplers, as well as a more realistic artificial heart.

This study aimed to find relationships between the presence of external factors, such as water vapor and smoke, and the ability of insects to communicate via pheromones. The results of the test of water vapor’s effect with the house crickets pointed towards the conclusion that water vapor can obstruct house cricket pheromone communication. The water vapor appeared to reduce the house cricket alarm response by blocking the volatile acetic acid molecules from being received by the crickets. The crickets in the experimental group in Experiment 1 showed an alarm pheromone social response when they were treated with volatile acetic acid. They ran around the container and tried to escape from it. Alternatively, the control group did not act differently than normal behavior, confirming that the acetic acid really did prompt the response. With this relationship established, water vapor’s effect on the pheromone communication could be tested. The results of this experiment (Experiment 2) confirmed what had been hypothesized: the pheromone prompt was much less effective with the water vapor present. The levels of activity for the experimental group in Experiment 1 (Figure 1) had been high, confirming that the social response had been prompted. In Experiment 2 (Figure 2), however, the activity levels were much lower in the alarm social response with water vapor present.

When testing smoke’s effect, the microscope images showed how smoke particles accumulated on the surfaces of the ants’ bodies over time. This confirms what was hypothesized. The smoke particle abundances of the ants treated with smoke trended upwards during the experimentation period (Experiment 3, Figures 3 and 4). The control ants did not show such trends. When it came to comparing the trends of different parts of the ants’ body in the experimental group, however, there was more of a surprise. For the antennae of the experimental group, there was a trend upwards in the accumulation of the smoke particles; however, it was not as steep a trend as other parts of the body. It was observed that the ants would rub on their antennae after the smoke doses with their two front legs. This is considered the reason why the trends for the antennae are not as steep, as they would clean some of the particles off themselves. In other body parts, such as the eyes of the ants, there was almost no accumulation in both the experimental group and the control group. The body parts with the sharpest trends in smoke particle accumulation included the thorax and the legs. In the control experiment, there were some particles of dust on the surfaces of the ants’ bodies; however, they were at significantly lower levels than the experimental group, and they remained static over time. In addition to observing the smoke particle abundances, the particle radii were measured (Figure 6). The most abundant particles visible through the microscope were those with a radius of approximately 150-175 μm. The particle sizes of least abundance lay in the 250-300 μm range. Knowing the particle sizes may prove useful in making future hypotheses about how smoke may affect insects anatomically.

Table 1

Table 1: Cricket activity scale.

The materials and methods used were designed to maximize accuracy and precision of the data collection, but some limitations did exist. The number of crickets used in each trial varied because some of them died during the timeframe of the experiment. However, regardless of the number of crickets used, the patterns viewed were the same during each trial. Another possible limitation is the substitute for cricket pheromone; if all the cricket alarm pheromone components had been used, there might have been a fuller alarm pheromone response. The full pheromone might create bigger and more significant differences in activity levels in the different trials. The limiting factors in experimentation with ants include the fact that the microscope was only able to view particles of 150 micrometers or larger. This means that there could have been particles less than 150 micrometers affecting the ants in a significant way.

The results of the investigation support the hypotheses of both projects. The smoke builds up at a slow rate on the bodies of the insects, and the water vapor can cause difficulties in pheromone communication between insects. These effects may help to identify factors that are causing colony collapse disorder. Though they might not be the direct or singular causes of CCD, they are possible explanations for the unanswered questions made by scientists and beekeepers. For example, long periods of a humid climate in a region may inhibit honey bees and other insects from communicating through pheromones. Since smoking is a standard method used by beekeepers when controlling a hive, it is also likely that smoke particles adhere to bees’ bodies in the same way that they adhere to ant’s bodies. It is also possible that the smoke irritation has a detrimental effect on the health of the bees in the hive. Future experiments should attempt to address these questions.