Sustainable Living Aboard Spacecraft
Modern spacecraft utilize complex recycling systems to maintain proper levels of atmospheric gases inside astronaut living spaces. Since we cannot reuse 100% of our waste, this is not a completely sustainable process. Longer expeditions would require bringing containers of oxygen or similar life support systems to ensure that the recycling process could go on as long as possible. Food is also a very important aspect of space travel, yet food cannot be recycled. Travelers must either bring all necessary food with them or grow it on board (Satyapal et al. 2001, Wieland 1998).
The only surefire way to fully maintain food and oxygen levels aboard a spaceship is via plants and their photosynthesis. The two types of plants typically considered for life support use are algae and higher plants. The benefits and drawbacks of these two types of plant life as detailed by Salisbury et al. are shown below in Figure 1 below
Figure 1. Benefits and drawbacks of algae and higher plants aboard spaceships, information retrieved from Salisbury et al.
The point that algae leads to nutrient deficiency over time is a very compelling component for the (primary) usage of higher plants. These plants can be grown by using xenon lamps roughly as powerful as sunlight. Although successful experimental trials have taken place in remote locations on Earth, there has not yet been an entirely successful attempt to grow a higher plant in outer space (Salisbury et al. 1997).
A more fully encompassing dietary recycling loop titled MELiSSA has been proposed. MELiSSA utilizes varied types of bacteria and plant life in four separate compartments to create a highly sustainable system of interactions (Hendrickx et al. 2005). The interaction diagram for the MELiSSA design as created by Hendrickx et al. is shown in Figure 2
Figure 2. “Scheme of the MELiSSA loop” retrieved from Hendrickx et al. 2005
It is important to note that life support systems go beyond the role of providing food, water, and comfortable living conditions for astronauts. These support systems must be able to decisively combat any sudden on-board emergency such as a fire. Fires rob the closed habitat of its precious oxygen and can throw sophisticated systems such as the MELiSSA loop into chaos. It is highly important to have fallback systems in place in case of emergency situations (Wieland 1994).
Future spacecraft may be extremely large, maybe the size of small cities. These spacecraft will be able to have complex sustainable life support systems of both plant and animal life. With a spaceship large enough, life on board can fully simulate life on Earth and provide thousands of travelers with an entirely stable habitat.
References:
Salisbury FB, Gitelson JI, Lisovsky GM. 1997. Bios-3: Siberian Experiments in Bioregenerative Life Support 575:585
Hendrickx L, De Wever H, Hermans V, Mastroleo F, Morin N, Wilmotte A, Janssen P, Mergeay M. 2005. Microbial ecology of the closed artificial ecosystem MELiSSA (Micro-Ecological Life Support System Alternative): Reinventing and compartmentalizing the Earth’s food and oxygen regeneration system for long-haul space exploration missions 77:86
Wieland P. 1994. Designing for human presence in space: An introduction to environmental control and life support systems Abstract
Satyapal S, Filburn T, Trela J, Strange J. 2001. Performance and Properties of a Solid Amine Sorbent for Carbon Dioxide Removal in Space Life Support Applications 250:255
Wieland PO. 1998. Living Together in Space: The Design and Operation of the
Life Support Systems on the International Space Station 1:59
Brief Literature Review of Pain Assessment
In his literature review of pain research, Bill Noble elaborates on the methods used to test effectiveness of analgesics between 1945 and 2000. His research outlines three different approaches: (1) psychophysics, (2) standardized words on questionnaires, and (3) verbal rating scales. Psychophysics is the oldest method of the three and it uses a stimulus to evoke pain (Hardy & Goodwell, 1940). The stimulus needed to elicit pain is quantified (pain threshold) and then subtracted from the maximum amount of stimulus that the subject is able to handle (pain tolerance) to get the difference (pain interval). The second method has a more clinical use as it is a survey format that asks patients to describe their pain using a set a standardized questions. The first of these surveys was the McGill Questionnaire, which Scarry also references in her analysis of how the assessment of physical pain in a clinical setting has changed. The third method of measuring pain Noble addresses is a verbal scale where patients express their pain on a numerical scale (Figure 1). All three methods have a place in modern medicine. (Noble)
Fig 1. Numerical scale used to quantify pain in people 3 years of age and older (Wong & Baker, 2001)
In their essay, Resnik and Rehm dissect why clinicians do not adequately address pain and what steps need to be taken in order to fix this issue. He points out that clinicians are firstly not given enough training on pain management. Secondly, they are often hesitant to prescribe analgesics because of possible side effects. Medical regulations also prohibit excess or unnecessary prescriptions of narcotics as they can lead to abuse of medication. Along with improper treatment of pain by the physician, inadequate communication of pain by the patient also contributes to the problem at hand. Patients sometimes hold back from expressing pain for various reasons (insurance does not always cover pain medication, pain can mean their illness is progressing, etc.) Resnik and Rehm suggest that retraining medical professionals in pain management would help to overcome this communication gap between physicians and patients. This encompasses using subjective descriptions of pain by patients for diagnosis, alternative methods of treatment pain outside of commercial medicine, and more conversation regarding pain between the physicians and patient to normalize the subject. (Resnik & Rehm, 2001)
Evidently, research has shown that pain is difficult to expressive because of its subjectivity. However, in clinical medicine, standardized questionnaires and scales are used to quantify pain and diagnose patients. These diagnoses are sometimes inaccurate because of confounding variables such as legal pressures against prescribing analgesics and the communication gap between physicians and their patients.
The sources examined in this literature review examine pain assessment from a clinical perspective. While this is a large application of pain assessment, there is little research about the cultural differences that come into play when looking at how pain is perceived and treated. Additionally, there seem to be several standard measures of pain assessment in modern medicine. Having several standards is the equivalent of having no standard. Another area of research that is currently not well studied is the existence of a universal standard to assess pain. Further research should evaluate current models of pain assessment to establish the strengths and weaknesses of each established method used in medicine today.
Citations:
Hardy, J. D., Wolff, H. G., & Goodell, H. (1940). Studies on pain. A new method for measuring pain threshold: observations on spatial summation of pain. Journal of Clinical Investigation, 19(4), 649.
Noble, B., Clark, D., Meldrum, M., ten Have, H., Seymour, J., Winslow, M., & Paz, S. (2005). The measurement of pain, 1945–2000. Journal of pain and symptom management, 29(1), 14-21.
Resnik, D. B., & Rehm, M. (2001). The undertreatment of pain: scientific, clinical, cultural, and philosophical factors. Medicine, Health Care and Philosophy, 4(3), 277-288.
Scarry, E. (1985). The body in pain: The making and unmaking of the world. Oxford University Press, USA.
Wong, D. L., & Baker, C. M. (2001). Smiling face as anchor for pain intensity scales. Pain, 89(2-3), 295-297.
Terraforming Celestial Bodies For Human Life: Mars Case Study
Manned galactic space travel, coupled with a population likely too large for the Earth, will inadvertently lead to human colonization of different planets and moons. The construction of safe indoor and outdoor living spaces on other planets requires changing the ecology and atmosphere of the planet to be friendly towards the species of Earth. It takes a monumental engineering effort for a planet to become habitable enough for an astronaut to land and be able to safely take off their spacesuit. Since the most viable planet closest to us is Mars, most ecopoiesis/terraforming research efforts are being directed there.
The first phase in making a planet hospitable to the human race is ecopoiesis, where an ecosystem is artificially constructed to begin altering the planet i.e. its atmosphere. The oxygen requirement for human life is nearly nonexistent, so photosynthesis is needed to transform the carbon dioxide of Mars (Thomas 1995). Earth plant life has a minimum requirement of about 10mbar of nitrogen, however, which would first need to be produced by Earth bacteria through denitrification (McKay et al. 1991, Friedman et al. 1995). Because of this, the first step in transforming the biosphere of Mars is to introduce large amounts of nitrogen-releasing bacteria to martian soil (Friedmann et al. 1995).
Once the atmosphere has enough nitrogen in it, plants engineered to survive on as low as 1mbar of oxygen can get to work on converting the massive amounts of carbon dioxide in the atmosphere – there is no observable limit to the maximum concentration of carbon dioxide conducive to Earth plant life. Sending species heavily resistant to UV damage would lead to the best results, as Mars has no ozone layer (Thomas 1995).
The resulting engineered atmosphere will still be too light for human life – the average pressure of Mars’s atmosphere is 6-10mbar while one Earth atmosphere is defined as 1bar. CFCs and other greenhouse gases are being considered as candidates for increasing the thickness of the martian atmosphere to weights friendly to humans. The increase of atmospheric density would also lead to the increase of global temperatures – the average martian surface temperature is -60 Celsius and would ideally need to rise at least 60 degrees to allow for liquid water (Budzik 2000). The increasing temperatures caused from the release of greenhouse gases would lead to the polar caps melting and heating the atmosphere even further in a positive feedback loop (McKay et al. 1991). Budzik claims that an initial increase of 4 degrees Celsius will result in a total increase of 55 degrees (Budzik 2000).
A very careful balance must be struck between the concentrations of the various gases in the newly engineered atmosphere to safely recreate the Earth’s atmosphere. A detailed breakdown of concentrations is provided by McKay et al. in Figure 1:
Figure 1. Atmospheric gas limits for sustainable human life retrieved from McKay et al. 1991
This transformation process of gas ratios is very lengthy and convoluted. Birch proposed an alternative method of evaporating the polar caps by using a giant (200,000 ton) mirror to redirect sunlight towards them (Budzik 2000, Birch 1992). Other more immediate methods include dropping bombs or redirecting asteroids to kick up large amounts of dust and make the atmosphere heavier (Budzik 2000).
The methods presented here can be adapted for barren dusty planets with polar caps. As we have not yet tried expanding to planets hotter than our own (e.g. Venus), we have not yet developed methods for terraforming these types of bodies. Although some planets may be completely uninhabitable, it is likely that the astronauts of the far distant future will be able to transform the vast majority of celestial bodies.
References:
Budzik JM. 2000. How to Terraform Mars: An Analysis of Ecopoiesis and Terraforming Research 1:17
Thomas DJ. 1995. Biological Aspects of the Ecopoiesis and Terraformation of Mars: Current Perspectives and Research 415:418
McKay CP, Toon OB, Kasting JF. 1991. Making Mars Habitable 489:496
Friedmann EI, Ocampo-Friedmann R. 1995. Advances in Space Research 243:246
Birch P. 1992. Terraforming Mars quickly Abstract
Detecting The Event Horizon of A Black Hole Using Radio Technology
Discovering and viewing the event horizon of a black hole has always been a goal of scientists since their speculation. They have intrigued the minds of many, as no one knows exactly what happens at the event horizon, or even if they truly exist as black holes could very much be taken as a mistake for something else. Many attempts in the past have been made to discover and view the event horizons of nearby black holes, and technology is still being used today in newer ways to extend this search and possibly reach the actual goal by finally finding the event horizons and viewing them. Newer methods have been proposed, but have yet to be tested.
Firstly, the black hole itself is difficult to view, as it is “not visible to the outside world” and “no signal can reach the region of space-time outside” a certain “Schwarzchild radius,” and the boundary in between this radius becomes known as the event horizon (Dolan, 2001). In a sense, discovering the black hole or its event horizon become synonymous where detecting the event horizon to the black hole leads to the proving and discovery of the black hole itself. Instead, x-ray and UV vision is used to detect and see black holes generally (Dolan, 2001). Another article discusses how the Hubble Space Telescope was able to collect data from a decade ago and how that data is being synthesized to “observe what seems to be the last gasp emitted by gaseous material spiraling Cygnus X-1, a suspected black hole 6,000 light-years from Earth” (Cowen, 2001). Blobs of hot gas supposedly spiraling and/or orbiting a black hole, radiate pulses of ultraviolet light, growing fainter rapidly and then just simply disappearing, lead to the expectation that these gases are about to enter the event horizon. Furthermore, the light emitted from these gasses “grows dimmer because the black hole’s gravity shifts the light to longer and longer wavelengths,” where radiation actually stops by the time the gas enters the black hole (Cowen, 2001).
Before using technology to find the event horizon, mathematical algorithms were created to find these event horizons, where they would make sense in theory. Once these algorithms were created, they would then be used in conjunction with radio technology, to detect and locate the black hole and its respective event horizon. In specific, Jonathan Thornburg uses “3 + 1 ADM formalism” to conduct calculations that help find the “apparent horizons in numerically-computed spacetimes” (Thornburg, 2001).
A new method of spacing out telescopes a great distance apart, and using the images collected by each of the three telescopes in a unifying manner has allowed scientists to attain a resolution much greater than the one provided by the Hubble Space Telescope. The new technique is called Very Long Baseline Interferometry and it exploits the phenomenon of interference, where multiple light waves are superimposed to amplify a signal (Wanjek, 2008). The technique of VLBI has been used to detect a massive radio source at the center of the Milky Way Galaxy, Sagittarius A. Very Long Baseline Interferometry allowed for three telescopes to achieve Sagittarius A’s first size measurement (Schwarzschild, 2008).
The James Clerk Maxwell Radio Telescope, served as one of three radio telescopes to form an array as part of Very Long Baseline Interferometry to achieve the first size measurement of Sagittarius A, a nearby black hole (Schwarzchild, 2008).
Works Cited
Cowen, R. “Peering At Black Holes: An Eventful Look.” Science News 159.3 (2001): 38.
Dolan, Joseph F. “How To Find A Stellar Black Hole.” Science 292.5519 (2001): 1079-1080.
Schwarzschild, Bertram. “Radio Interferometry Measures The Black Hole At The Milky Way’s Center.” Physics Today 61.11 (2008): 14-18.
Thornburg, Jonathan. “Event And Apparent Horizon Finders For 3+1 Numerical Relativity.” Living Reviews In Relativity 10.4 (2007): 1-68.
Wanjek, Christopher. “Radio Dishes Tune In To Event Horizon.” Mercury 37.4 (2008): 9.
Is it More Helpful or Harmful? Evaluating the Impact of Cyberknife Radiosurgery on Pain Elimination
One important area of research for the Cyberknife system is the study of its impact on improving pain after treatment. As previous assignments have suggested, the Cyberknife holistically shows promise as a precise and effective alternative treatment method for people suffering from various types of cancer. What has not been explored as in depth is the impact of the Cyberknife system on pain post-treatment. Though the device may be able to shrink tumors and kill off cancer very precisely, a person’s quality of life (QOL) may not be very good if he or she is still experiencing pain after treatment. The objective of this paper was to evaluate the impact of the Cyberknife on pain elimination for cancer patients.
Past literature has indicated that the Cyberknife is capable of maintaining quality of life post-treatment. But within the realm of QOL exists the experience of pain. Research related to pain treatment has predominantly been conducted for patients battling cancers of the nervous system. Few articles have been published exploring this. For example, two research articles have been reported stating that although QOL was not significantly effected for cancer patients with spinal lesions, the Cyberknife system did significantly improve patient pain post-treatment (Degan et al., 2005; Gagnon et al., 2009). Additional research has reported similar findings. For example, in a 10 patient sample undergoing Cyberknife treatment for trigeminal neuralgia, 7 of the patients experienced pain relief (Romanelli et al., 2003). In a study evaluating Cyberknife treatment for 41 patients with trigeminal neuralgia, 36 patients (~88%) reported excellent pain control, 2 reported moderate, and 3 reported no change in pain at a median of 1week post treatment (Lim et al., 2005). Recurrence of pain was experienced in 6 patients 6 months post treatment (Lim et al., 2005), suggesting that the pain relief for this patient sample was immediate but then returned shortly after treatment (Lim et al., 2005). Similar findings were reported in research conducted by Singh on trigeminal neuralgia treatment; a majority of patients experienced immediate pain relief (Singh et al., 2016). Lastly, in research evaluating the treatment of the Cyberknife on atypical trigeminal neuralgia, 4 out of 7 patients experienced immediate pain relief, 2 had minimal relief, and 1 reported no change (Patil et al., 2007).
Figure 1: Kaplan-Meier curve for TN1 patients. 28 out of the initial 125 TN1 patients performed follow-ups of greater than 1 year post treatment. 82% of patients low pain scores one year after treatment. 11 patients had follow-ups of greater than two years after treatment; 72% reported lower pain scores 2 years post-treatment. Out of 5 patients performing the 3-year post treatment survey, 40% experienced total symptom relief. (Singh et al., 2016).
Overall, the literature in this field suggests that the Cyberknife system has an immediate positive impact on reducing pain, specifically for those suffering from cancers of the nervous system.
References
Degen, J. W., Gagnon, G. J., Voyadzis, J., Mcrae, D. A., Lunsden, M., Dieterich, S., Henderson, F. C. (2005). CyberKnife stereotactic radiosurgical treatment of spinal tumors for pain control and quality of life [Abstract]. Journal of Neurosurgery: Spine, 2(5), 540-549.
Gagnon, G. J., Nasr, N. M., Liao, J. J., Molzahn, I., Marsh, D., Mcrae, D., & Henderson, F. C. (2009). Treatment Of Spinal Tumors Using Cyberknife Fractionated Stereotactic Radiosurgery [Abstract]. Neurosurgery, 64(2), 297-307.
Lim, M., Villavicencio, A., Burneikiene, S., Chang, S., & Adler, J. (n.d.). CyberKnife radiosurgery for idiopathic trigeminal neuralgia. Neurosurg Focus, 18(5), 1-7.
Patil, C. G., Veeravagu, A., Bower, R. S., Li, G., Chang, S. D., Lim, M., & Adler, J. R. (2007). CyberKnife radiosurgical rhizotomy for the treatment of atypical trigeminal nerve pain [Abstract]. Neurosurgical FOCUS, 23(6).
Romanelli, P., Heit, G., Ching, S., Pham, C., & Adler, J. (2003). Cyberknife Radiosurgery for Trigeminal Neuralgia [Abstract]. Karger, 81.
Singh, R., Davis, J., & Sharma, S. (2016). Stereotactic Radiosurgery for Trigeminal Neuralgia: A Retrospective Multi-Institutional Examination of Treatment Outcomes. Cureus, 8(4).
Music Through the Lens of Neuroscience and Psychology
I have chosen the focus of this writing assignment to be apart from my video project about the Mars mission. I play many instruments of music, in a lot different genres, and my love of listening to music is even more diverse and extensive. I use music as a therapy, a creative output, a stimulant, a pastime, and an aide to any social situation. I have always been fascinated about the science behind humanity’s affection for this art of sound, and what neurological and psychological research has uncovered about one of the oldest and most prolific forms of culture.
In one study, 16 participants listened to 5 characteristically happy songs, 5 sad songs, and 10 neutral songs, all in the genre of classical music, while inside of an fMRI machine. Blood oxygenation level dependent (BOLD) signal contrasts were used to indicate which parts of the brain were most active under the influence of the music. With happy music, the ventral and dorsal striatum, anterior cingulate, parahippocampal gyrus, and auditory association areas received BOLD signal contrasts, commonly areas of the brain associated with reward, movement, and emotional processing. The hippocampus/amygdala region received a BOLD signal contrast with sad music, commonly associated with memory and emotions. The study showed the neurological response of different areas of the human brain to music of different moods (Mitterschiffthaler et al., 2007).
Another study used an fMRI machine to compare the neurological differences in language and music. A 29-year-old bilingual pianist, literate in both Japanese and English, underwent a series of fMRI tests while reading Japanese, English, and a musical score. Figure 1 shows images of the fMRI results of the three categories, showing the similarities between processing written music and written language. However, there are differences, such as in the right transverse occipital sulcus, which can be accounted by written music’s representation of rhythm and pitch. These aspects require more cortical processing (Nakada et al., 1998).
Figure 1: fMRI images of the regions of the participant’s brain (shown in red and yellow) that responded most to reading the three categories of language: Japanese, English, and music.
Aside from these fascinating insights of music’s effects on the physical brain, psychological research has also demonstrated music’s strange influence. A study on 60 college students, 30 biology majors and 30 music majors, tried to determine whether musical education influenced biological responses to two types of music. Plasma levels of cortisol and norepinephrine were measured before and after listening to both musical pieces, and galvanic skin responses were measured as well. The study concluded that cortisol levels and galvanic skin responses were significantly higher after listening for music majors than for biology majors, and that cortisol increase is a good indicator of analytical and critical listening to music (VanderArk & Ely, 1993).
A case study of two patients suffering from frontotemporal dementia (FTD) investigated a sudden development of taste in pop music. A 68-year-old lawyer, whose musical preference had always been classical, and who regarded pop music as “mere noise,” began listening to Italian pop music two years after being diagnosed with FTD. After three years, he began listening for hours every day, until his death four years after the diagnosis. A 73-year-old housewife originally could not tolerate listening to music, and only did so for occasional dance songs, until she developed a great affinity for Italian pop music one year after her diagnosis of FTD. This study builds on past research of dementia patients developing greater preferences and abilities in art and music (Geroldi et al., 2000).
79 participants with an ICD-10 diagnosis of depression were randomized to receive individual therapy, in the form of standard care with music therapy or standard care alone, for 20 weeks. Figure 2 displays the results of the study, showing that participants who received the standard care with music therapy had far better improvements in psychiatric scores than those who only received psychiatric care (Erkkila, 2011).
Figure 2: The results of five psychiatric tests, with change in scores on the y-axis and time in months on the x-axis. (a) Montgomery–Åsberg Depression Rating Scale; (b) Hospital Anxiety and Depression Scale – Anxiety; (c) Global Assessment of Functioning; (d) Toronto Alexithymia Scale – 20; (e) Health-related quality of life scale RAND–36.
Works Cited
Erkkila, Kaakko, Marko Punkanen, Jorg Fachner, et al. “Individual music therapy for depression: randomised controlled trial.” The British Journal of Psychiatry. 199, no. 2 (July, 2011) [Cited 20 November 2016].
Geroldi, Cristina, Tizina Metitieri, Giuliano Binetti, et al. “Pop Music and Frontotemporal Dementia.” Neurology. 55, no. 12 (December, 2000) [Cited 20 November 2016].
Mitterschiffthaler, Martina T., Cynthia H.Y. Fu, Jeffrey A. Dalton, et al. “A functional MRI study of happy and sad affective states induced by classical music.” Human Brain Mapping. 128, no. 11 (November, 2007) [Cited 20 November 2016].
Nakada, Tsutomu, Yukihiko Fujii, Kiyotaka Suzuki, et al.“‘Musical brain’ revealed by high-field (3 Tesla) functional MRI.” Cognitive Neuroscience. 9, no. 17 (December, 1998) [Cited 20 November 2016].
VanderArk, Sherman D., Daniel Ely. “Cortisol, biochemical, and galvanic skin responses to music stimuli of different preference values by college students in biology and music.” SAGE Journals. 77, no. 1 (August, 1993) [Cited 20 November 2016].
Searching for Search Algorithms in Yelp
According to Alexa.com, the most popular sites are search engines with Google.com as the leading provider on the World Wide Web. Practically, it is easy to see why this is so. The World Wide Web is an information system of documents that may be linked together with hyperlinks. These documents can be accessed via the Internet, which is a system of interconnected computer networks. To be able to access these documents, the address of the website needs to either be known or “Googled”. While Google didn’t pioneer search engines, it is indeed on the forefront of search engine technology. As the company is dominant in this industry, it become a verb, so to speak. As there are billions of documents on the internet, a search query would seemingly take ages. However, Google searches take less than a second on average as the time is listed whenever you make a search.
The whole concept of searches stems from information retrieval – “a field concerned with the structure, analysis, organization, storage, searching, and retrieval of information.” (Croft, et al.) Generally, there are many types of searches in Computer Science. The most simple of all is the linear search where you traverse an array linearly to compare the value of each index to find a target. Another interesting search is the binary search which is seen in the figure. When given a sorted array, simply divide and conquer by asking: is the target greater or smaller than the current index being looked at in the array? A decision tree is shown that will clarify the process for a binary search (Horowitz).
Figure 1: Binary Search Decision Tree (Horowitz)
Google is a crawler-based search engine in that it is divided into three tasks. First, there is a “spider” that goes through a website and all of the links in the directory of that web server. Second, these web pages are coped into an index that will allow for the final step where a search engine software will traverse the index to find pages that would satisfy a target (Sullivan). As discussed before, we know what a linear search and binary search is. A linear search simply could not suffice for billions of pages as your daily Google search will take hours and maybe even days. A binary search would also take very long. Suppose for a small data set, we used a binary search. Entering a search query would then go through this index of pages that point to a set of documents based on the keywords in the search query.
People that use Google for the most part only want a few pages out of the hundreds of thousands of documents returned. An estimated 85% of queries only had the first page of results requested (Henziner, et al.). As there are many results, it is given that users would only want a small subset to satisfy their request (Joachims). How does this relate to Yelp? Like any search engine, it utilizes an indexing system that would allow it to search for restaurants and businesses efficiently. If you did a linear search through the many businesses in Manhattan alone for Alice’s Tea Cup, the resources exhausted for merely one query would be unsustainable in a searching service. By indexing keywords, Yelp can easily return a list of restaurants with a simple search. Furthermore, Yelp’s discrete tags allow you to filter restaurants based on their accommodations and cuisine.
Works Cited
Croft, W. Bruce, Donald Metzler, and Trevor Strohmann. Search engines. Pearson Education, 2010.
Henzinger, Monika R., Rajeev Motwani, and Craig Silverstein. “Challenges in web search engines.” ACM SIGIR Forum. Vol. 36. No. 2. ACM, 2002.
Horowitz, Ellis, and Sartaj Sahni. Fundamentals of computer algorithms. Computer Science Press, 1978.
Joachims, Thorsten. “Optimizing search engines using clickthrough data.” Proceedings of the eighth ACM SIGKDD international conference on Knowledge discovery and data mining. ACM, 2002.
Sullivan, Danny. “How search engines work.” SEARCH ENGINE WATCH, at http://www. searchenginewatch. com/webmasters/work. html (last updated June 26, 2001)(on file with the New York University Journal of Legislation and Public Policy) (2002).
Who is really flying in the cockpit?
At any given time, there are more than 5,000 airplanes in United States Airspace transporting passengers to one of over 19,000 airports around the country. Tens of thousands of hours are spent in the sky on any given day and accompanied on every flight is the plane’s autopilot system (Awad, Wang).
When air travel was first introduced, flying demanded complete control by the pilot. As air travel became more advanced, longer flight routes became possible making pilots more likely to experience fatigue. Autopilot systems were created to automate some of the tasks and make flying easier (Efimov, Raissi).
Planes are controlled three dimensionally by adjusting the pitch, yaw, and roll. A change in pitch would point the nose of the plane up or down, yaw left or right, and roll would rotate the length of the plane left or right. These adjustments are made by moving the elevators, the rudder, and ailerons respectively. A basic autopilot system works by mechanizing control of pitch, yaw, or roll by the given parameters of the pilot (Damiano, Fatiha).
In the case of commercial aircraft, the autothrottle and autopilot is maneuvered by a highly equipped navigation computer, known as a “Flight Management System” that is installed onboard. The programming of the Flight Management System is done by the pilot himself before flight to control the altitude, cruising speed, and landmarks being entered. The Flight Management System employs radio signals and instrument readings from fixed points on the ground to find out what adjustments need to be made in order to meet the flight plan (Damiano, Fatiha).
Since these advanced autopilot systems are beneficial to the pilot and accurate in maximizing efficiency, they are almost always employed throughout a commercial flight. However, human pilots are still necessary and take control of the aircraft during takeoff and landings and sometimes during mid flight (Zohlgadri).
Automated systems can be very helpful when weather conditions are not ideal or when emergencies are happening. Rather than relying on visual cues that pilots need in order to fly safely, these systems use radar to technology to fly and even land planes. Without these systems, cloudy weather and fog makes commercial aircraft almost impossible to land by pilots themselves (Surnan, Widborne).
Figure 1: Flowchart showing how the autopilot reads and processes information.
Figure 2: Diagram of the mechanical functions of the airplane
References:
Shaoming He, Jiang Wang, Defu Lin. (2016) Robust Missile Autopilots With
Finite-TimeConvergence. Asian Journal of Control 18:3, 1010-1019
- Awad, H. P. Wang. (2016) Integrated Pitch-Yaw Acceleration Autopilot Design for
Varying-Velocity Man Portable Missile. International Journal of Modeling and Optimization 6:1, 11-17 Online publication date: 1-Jan-2016.
- Efimov, T. Raissi, W. Perruquetti, A. Zolghadri. (2015) Design of interval observers
for estimation and stabilization of discrete-time LPV systems. IMA Journal of Mathematical Control and Information Online publication date: 7-Jun-2015.
Damiano Rotondo, Fatiha Nejjari, Vicenç Puig, Joaquim Blesa. (2015) Model reference
FTC for LPV systems using virtual actuators and set-membership fault
estimation. International Journal of Robust and Nonlinear Control 25:5, 735-760
Online publication date: 25-Mar-2015.
Sunan Chumalee, James F. Whidborne. (2015) Gain-Scheduled H ∞ Control for Tensor
Product Type Polytopic Plants. Asian Journal of Control 17:2, 417-431
Online publication date: 1-Mar-2015.
Fiducial Markers: An Important Tool for the Cyberknife’s Motion Tracking Capability
The past several assignments have explicitly focused on evaluating aspects of the Cyberknife system, such as the treatment method’s precision, efficacy, and cost-effect ratio. What has yet to be explored among these assignments is an important tool that essentially enables the Cyberknfie to do its job and effectively treat patients with various types of cancers. This important tool is known as a fiducial marker.
One of the main aspects of the Cyberknife system that makes it unique from other cancer treatment methods is that it can correct for patient motion while it is delivering radiation to a target cancer site. What enables the Cyberknife to do this is the use of gold fiducial markers. Past scientific literature in this field has predominantly focused on the use of fiducial markers for prostate cancer. Fiducial markers are placed into patients’ prostates in either a transperineal or transrectal manner under the guidance of a transrectal ultrasound (Hellinger et al., 2015). The Cyberknife is able to offer real time movement correction when delivering radiation by monitoring the positions of the fiducial markers with the use of a digital x-ray (Hellinger et al., 2015).
Fig 1: Fiducial markers in the prostate. The markers are inserted into the prostate (2 are visibly sparkling the center of the figure) and then used by the X-ray portion of the Cyberknife to track and correct for position changes made by patients undergoing treatment. (Hellinger et al., 2015)
Variations on fiducial markers have been produced over the years as a means of developing a more accurate way of localizing the prostate so that treatment from the Cyberknife can be delivered more precisely. A few of these variations include round markers, cylindrical markers, and elongated markers (Boer et al., 2012). Research conducted in 2012 specifically sought to evaluate the number of elongated fiducial markers that would produce the most accurate localization of the prostate during treatment (Boer et al., 2012). Using either 1, 2 or 3 markers for 24 patients, the researchers saw that placing 2 markers, one on each side of the prostate, was able to accurately locate the prostate; using 1 produced a larger position tracking error and using 3 produced a tracking error (0.3-0.8mm) similar to 2 markers (0.4-1mm) (Boer et al., 2012). Furthermore, research conducted in 2008 suggested that fiducial markers enable the Cyberknife x-ray to keep the prostate in tracking range at approximately 40 seconds between consecutive x-rays (Xie et al., 2008).
Additional research has been conducted not only to understand the capacity of fiducial markers and their impact on prostate movement tracking, but on improving the Cyberknife’s ability to track prostate motion. A study published in 2011 specifically focused on acquiring a six-dimensional prostate motion tracking system (Lei et al., 2011). In contrast to research by Boer mentioned above, 4 fiducial markers were placed at least 2 cm apart in the prostate in order to obtain 6D motion tracking for Lei’s patient sample (Lei et al., 2011). In 98% of the 88 patients undergoing the Cyberknife system with the use of fiducial markers, at least one fiducial marker met the criteria for 6D correction of prostate motion (Lei et al., 2011). By obtaining 6D motion tracking, a higher dose of radiation could be imposed on a patient to ultimately reduce the number of fractions he would have to undergo in order to treat his cancer.
One incredibly important factor to consider when it comes to any form of treatment for cancer are the complications that may result from it. In addition to exploring 6D motion tracking, Lei’s article reported that patients did not experience complications higher than grade 2 (Lei et al., 2011). Additional research reviewed 270 fiducial markers placed in 77 patients; 31 of these implants were placed into the prostate (Kim et al., 2012). 21% of the patients experienced minor complication rates either before and during treatment; 1% experienced severe complications (Kim et al., 2012). 2.2% of fiducial markers migrated from initial implantation sites. 96.7% of the implants were considered successful (Kim et al., 2012). In another study by Gill, the authors noted that out of the 234 patients assessed, 32% reported at least one new symptom post treatment (Gill et al., 212). However, most of the symptoms presented were considered either grade 1 or grade 2, such as urinary frequency and mild rectal bleeding, and often lasted less than 2 weeks (Gill et al.,2012).
Overall, this paper focused on evaluating the importance of fiducial markers for the use of the Cyberknife system for prostate cancer patients. The articles provided information on different types of fiducial markers, how they aid in motion tracking, ways of improving motion tracking with their use, and ultimate safety and efficacy were all assessed. It appeared that the fiducial markers had a high success rate for 6D correction and often did not result in incredible severe complications post treatment. Despite this, it is important to note that 32% of patients undergoing radiation therapy paired with fiducial markers experienced some grade level of complication as a result of the fiducial markers and treatment.
References
Boer, J. D., Herk, M. V., & Sonke, J. (2012). The Influence Of The Number Of Implanted Fiducial Markers On The Localization Accuracy Of The Prostate [Abstract]. IOP Science, 57(19).
Gill, S., Li, J., Thomas, J., Bressel, M., Thursky, K., Styles, C., Foroudi, F. (2012). Patient-reported complications from fiducial marker implantation for prostate image-guided radiotherapy. The British Journal of Radiology, 85(1015), 1011-1017.
Hellinger, J. C., Blacksberg, S., Haas, J., & Melnick, J. (2015, September). Interventional uroradiology in the management of prostate cancer. Applied Radiology, 40-41.
Kim, J. H., Hong, S. S., Kim, J. H., Park, H. J., Chang, Y., Chang, A. R., & Kwon, S. (2012). Safety and Efficacy of Ultrasound-Guided Fiducial Marker Implantation for CyberKnife Radiation Therapy. Korean Journal of Radiology, 13(3), 307-313.
Lei, S., Piel, N., Oermann, E. K., Chen, V., Ju, A. W., Dahal, K. N., Collins, S. P. (2011). Six-Dimensional Correction of Intra-Fractional Prostate Motion with CyberKnife Stereotactic Body Radiation Therapy. Frontiers in Oncology, 1, 1-12.
Xie, Y., Djajaputra, D., King, C. R., Hossain, S., Ma, L., & Xing, L. (2008). Intrafractional Motion of the Prostate During Hypofractionated Radiotherapy. International Journal of Radiation Oncology*Biology*Physics, 72(1), 236-246.
Cyberknife Linked to Maintaining Cancer Patient Quality of Life Scores Before and After Treatment
As previously mentioned, the Cyberknife is a radiosurgery technique used to target and treat cancerous masses in the body. Although this treatment method has become popular recently, various research studies have been published on the Cyberknife. For example, past literature has evaluated the precision of the Cyberknife, how it is able to track and correct for patient motion, its efficacy, as well as the overall cost-effect ratio of the system. In addition to exploring all of these factors, it is incredibly important for researchers to evaluate the impact of the Cyberknife system on quality of life for cancer patients.
Before delving into literature on this topic, it is useful to define the phrase “quality of life,” or QOL. A hypothesized meaning of the term is the measurement of the difference between a person’s expectations for their lives and their present day life experiences (Calman, 1984). Past research has been published regarding the impact of the Cyberknife system on quality of life for cancer patients. For instance, a 2014 study evaluated urinary, bowel, and sexual QOL scores for prostate cancer patients at baseline and numerous times post-treatment (Katz et al., 2013). Out of the patients assessed, mean urinary and bowel QOL declined 1-month post treatment and returned to baseline after two years; at 6-12 months, sexual QOL declined by a mean of 23% and remained stable afterward (Katz et al., 2013). Similar findings were reported in a follow-up QOL assessment conducted by Katz (2014). Thus, this research focused on prostate cancer indicates that the Cyberknife does not have a particularly positive impact on patient quality of life post-treatment.
Figure 1: Quality of life scores for prostate cancer patients post-cyberknife treatment. The graph represents the mean and standard QOL scores for patients at baseline and up to three years post treatment. Bowel, urinary, and sexual QOL were assessed for this patient sample. The graph indicates that bowel and urinary QOL dipped post-treatment but eventually returned to baseline, whereas sexual QOL slightly decreased overtime without returning to baseline. (Katz et al., 2013)
In addition to prostate cancer, research on this topic has been conducted on patients being treated for spinal tumors. After undergoing Cyberknife treatment, patients with spinal lesions completed quality of life surveys (Gagnon et al., 2009). Patients exhibited no significant changes in physical quality of life post-treatment, but they did exhibit significantly higher mental quality of life scores post treatment (Gagnon et al., 2009). Research published by Degen on spinal tumor treatment suggested that mental and physical well-being QOL remained relatively constant both before Cyberknife treatment and up to two years post-treatment (2005). Both of these studies on spinal tumor treatment indicated that the Cyberknife system had a significant impact on improving patient pain post-treatment (Gagnon et al., 2009; Degan et al., 2005).
Overall, literature regarding the impact of the Cyberknife system on QOL for cancer patients depict quite similar findings. This treatment method does not have a significant impact on improving or reducing QOL post-treatment, but appears to stabilize QOL overtime. Although findings were not considered significant, QOL for sexual functioning of prostate cancer patients decreased and was maintained at that level numerous years post-treatment (Katz et al., 2013 & 2014). Although QOL was not significantly effected for cancer patients with spinal lesions, the Cyberknife system did significantly improve patient pain post-treatment (Gagnon et al., 2009; Degan et al., 2005).
Despite the insignificant findings presented, a majority of the research suggests that the Cyberknife essentially maintained QOL scores before and after treatment. In the future, it would be important for research to compare QOL scores for patients undergoing Cyberknife versus other treatment methods. Research in this field could help elucidate which treatment method has the best impact on patients perceptions of their physical and mental QOL and would ultimately enable them to return back to their daily lives at a faster pace.
References
Calman, K. C. (1984). Quality of life in cancer patients–an hypothesis. [Abstract]. Journal of Medical Ethics,10(3), 124-127.
Degen, J. W., Gagnon, G. J., Voyadzis, J., Mcrae, D. A., Lunsden, M., Dieterich, S., Henderson, F. C. (2005).CyberKnife stereotactic radiosurgical treatment of spinal tumors for pain control and quality of life [Abstract]. Journal of Neurosurgery: Spine, 2(5), 540-549.
Gagnon, G. J., Nasr, N. M., Liao, J. J., Molzahn, I., Marsh, D., Mcrae, D., & Henderson, F. C. (2009). Treatment Of Spinal Tumors Using Cyberknife Fractionated Stereotactic Radiosurgery [Abstract]. Neurosurgery, 64(2), 297-307.
Katz, A. J., Santoro, M., Diblasio, F., & Ashley, R. (2013). Stereotactic body radiotherapy for localized prostate cancer: Disease control and quality of life at 6 years. Radiation Oncology, 8(1), 118-125.
Katz, A. J., & Kang, J. (2014). Quality of Life and Toxicity after SBRT for Organ-Confined Prostate Cancer, a 7-Year Study. Frontiers in Oncology, 4.
