Preferences of fourth grade children for certain social studies activities.

Thesis (Ed.M.)--Boston Universit

The Relevance of Relevance: Section 215 of the USA PATRIOT Act and the NSA Metadata Collection Program

In June 2013, a National Security Agency (NSA) contractor, Edward Snowden, leaked classified documents exposing a number of secret government programs. Among these programs was the “telephony metadata” collection program under which the government collects records from phone companies containing call record data for nearly every American. News of this program created considerable controversy and led to a wave of litigation contesting the validity of the program. The legality of the metadata collection program has been challenged on both constitutional and statutory grounds. The program derives its authority from Section 215 of the USA PATRIOT Act, codified as 50 U.S.C. § 1861. The statute requires that there be reasonable grounds to believe the data collected is “relevant to an authorized investigation.” The government deems all these records “relevant” based on the fact that they are used to find patterns and connections in preventing terrorist activity. Critics of the program, however, assert that billions of records cannot possibly be relevant when a negligible portion of those records are actually linked to terrorist activity. This Note examines the conflicting interpretations of “relevant,” and concludes that while the current state of the law permits bulk data collection, the power of the NSA to collect records on such a large scale must be reined in

The Rise of Computerized High Frequency Trading: Use and Controversy

Over the last decade, there has been a dramatic shift in how securities are traded in the capital markets. Utilizing supercomputers and complex algorithms that pick up on breaking news, company/stock/economic information and price and volume movements, many institutions now make trades in a matter of microseconds, through a practice known as high frequency trading. Today, high frequency traders have virtually phased out the dinosaur floor-traders and average investors of the past. With the recent attempted robbery of one of these high frequency trading platforms from Goldman Sachs this past summer, this rise of the machines has become front page news, generating vast controversy and discourse over this largely secretive and ultra-lucrative practice. Because of this phenomenon, those of us on Main Street are faced with a variety of questions: What exactly is high frequency trading? How does it work? How long has this been going on for? Should it be banned or curtailed? What is the end-game, and how will this shape the future of securities trading and its regulation? This iBrief explores the answers to these questions

Using abundance data to assess the relative role of sampling biases and evolutionary radiations in Upper Muschelkalk ammonoids

The Middle Triassic ammonoid genus Ceratites diversified spectacularly within the Germanic Muschelkalk Basin during the Anisian/Ladian (244–232 Mya). Previous studies have interpreted this diversification as a sequence of rapid, endemic radiations from a few immigrant taxa. Here we investigate the possibility that geological and sampling biases, rather than ecological and evolutionary processes, are responsible for this pattern. A new specimen based dataset of Ceratites species-richness and abundance was assembled. This dataset was combined with 1:200000 geological maps in a geodatabase to facilitate geospatial analyses. One set of analyses compared species richness per geological map with the number of occurrences and localities per map. Per-map change in the amount of rock available to sample for fossils was also included as a variable. Of these three variables, number of occurrences is the most strongly correlated with richness. Variation in the amount of rock is not a strong determinant of species-richness. However, rarefaction of basin-wide species/abundance data demonstrates that differences in species-richness through time are not attributable to sample size differences. The average percent similarity among sites remained close to 50% throughout the Upper Muschelkalk. The rank abundance distribution (RAD) of species from the first interval of the Upper Muschelkalk is consistent with colonization of a disturbed environment, while the other two intervals have RADs consistent with more stable ecosystems. These results indicate that genuine ecological and evolutionary events are partly responsible for the observed differences in richness and abundance. Although changes in the RADs through time support changes in the ammonoid assemblage structure, the processes underlying increasing richness and change in RADS cannot be explained by increasing geographic distinctiveness or isolation among the ammonoid assemblages present at different localities

Stress intensity factors for deep cracks emanating from the corner formed by a hole intersecting a plate surface

A technique consisting of freezing photo-elasticity and a numerical method was used to obtain stress intensity factors for natural cracks emanating from the corner at which a hole intersects a plate surface. Geometries studied were: (1) crack depth to thickness ratios of approximately 0.2, (2) 0.5 and 0.75; (3) crack depth to crack length ratios of approximately 1.0 to 2.0; and (4) crack length to hole radius ratios of about 0.5 to 2.0. All final crack geometries were grown under monotonic loading and growth was not self similar, with most of the growth occuring through the thickness under remote extension. Stress intensity factors were determined at the intersection of the flaw border

Stress intensity factors for deep cracks emanating from the corner formed by a hole intersecting a plate surface

A technique consisting of a marriage between stress freezing photoelasticity and a numerical method was used to obtain stress intensity factors for natural cracks emanating from the corner at which a hole intersects a plate surface. Geometrics studied were: crack depth to thickness ratios of approximately 0.2, 0.5, and 0.75; crack depth to crack length ratios of approximately 1.0 to 2.0. All final crack geometries were grown under monotonic loading and growth was not self similar with most of the growth occurring through the thickness under remote extension. Stress intensity plate surface K sub s factors were determined at the intersection of the flaw border with the plate surface K sub s and with the edge of the hole K sub h. Results showed that for the relatively shallow flaws K sub h approximately equal to 1.5 K sub s, for the moderately deep flaws K sub h approximately equal to K sub s, and for the deep flaws K sub h approximately equal to 0.5 K sub s, revealing a severe sensitivity of K to flaw geometry

A plane strain analysis of the blunted crack tip using small strain deformation plasticity theory

A deformation plasticity analysis of the tip region of a blunted crack in plane strain is presented. The power hardening material is incompressible both elastically and plastically, in order to simulate behavior of a stress freezing material above critical temperature. Stress and displacement fields surrounding the crack tip are presented. The results indicate that the maximum stress seen at the crack tip is indeed limited and is determined by the tensile properties; however, the scale over which the stresses act is dependent on the loading. Comparisons are good between the forward crack tip displacement and micro-fractographic measurments of stretch zones observed in plane strain fracture toughness tests

A simplified method for thermal analysis of a cowl leading edge subject to intense local shock-wave-interference heating

Type IV shock wave interference heating on a blunt body causes extremely intense heating over a very localized region of the body. An analytical solution is presented to a heat transfer problem that approximates the shock wave interference heating of an engine cowl leading edge of the National Aero-Space Plane. The problem uses a simplified geometry to represent the leading edge. An analytical solution is developed that provides a means for approximating maximum temperature differences between the outer and inner surface temperatures of the leading edge. The solution is computationally efficient and, as a result, is well suited for conceptual and preliminary design or trade studies. Transient and steady state analyses are conducted, and results obtained from the analytical solution are compared with results of 2-D thermal finite element analyses over a wide range of design parameters. Isotropic materials as well as laminated composite materials are studied. Results of parametric studies are presented to indicate the effects of the thickness of the cowl leading edge and the width of the region heated by the shock wave interference on the thermal response of the leading edge

Studies in immunity: more especially with reference to some of the reactions of complement; and, to the seat of origin of complement and immune body

#1. The method of investigating the seat of origin of antibodies, especially the haemolysins, bactericidal bodies and precipitins, by means of "Organ extracts" is valueless: and no reliance can be placed on results derived by such a method. #2. Normal rabbits, injected intravenously with ox blood corpuscles, show Immune body, in their blood, against ox blood corpuscles, for the first time, on or about the third day. #3. Normal rabbits, from which the spleen alone, the spleen and thyroid, the thyroid alone, or one Kidney has been removed and into which, within a week or so after the operation, ox blood corpuscles have been injected intravenously, show, like the controls, Immune body, against ox blood corpuscles * for the first time on or about the third day. #4. The total leucocyte count of perfectly normal rabbits may vary in different individuals between roughly 4,000 and 15,000; in individual rabbits, in ordinary and exaggerated conditions of laboratory life, as regards feeding time of day &c., the total leucocytes do not vary beyond 3,000 on either side of a mean per Cram,that is beyond the limits to be allowed for experimental error. #5. The differential count, as regards polymorphonuclears and lymphocytes, varies so much, under ordinary laboratory conditions, in the same rabbit, at different times, and in different rabbits, that conclusions should be drawn, with great caution, from any variation under experimental conditions. #6. The spleen was removed from a normal rabbit. Two days after its removal, it was injected intravenously with ox blood corpuscles. Immune body appeared in its blood in three days and yet there was no leucocytosis. To adopt the usual criterion this may be taken as evidence that a compensatory action on the part of the hone marrow and lymphatic apparatus has been excluded. #7. Injections into normal rabbits, intravenously, intraperitoneally, and subcutaneously, of even large amounts of ox blood corpuscles do not produce a variation in the total leucocyte count beyond that in control animals. #8. Such injections, - and I speak here with the greatest caution - produce no effect on the differential count. #9. From the above results, I would conclude provisionally, that so far as such methods can settle such a question, there is great probability that neither, the spleen, nor the bone marrow, nor the lymphatic apparatus, nor the kidney, is the seat of formation in rabbits, of Immune body against ox blood corpuscles. #10. Normal rabbits, from whom blood, a haemoiysin, agglutinin and precipitin for ox blood has been carefully excluded, after being fed for some time on ox blood, show in their blood all of these active principles. This gives some support to the view, to be advanced in this paper, that the formation of antibodies is allied to the ordinary physiological processes of assimilation: and as the liver is accredited by physiologists with a high role in such processes, to the liver being regarded provisionally as a possible seat of formation of Immune body, - (for sensitised ox blood corpuscles. #11. The amount of complement in leech, citrate, fluoride, and oxalate plasmas of the rabbit is the same as in the corresponding leech, citrate, fluoride, and oxalate sera. #12. Normal aqueous humour of rabbits and the fluid from a tape worm cyst of the rabbit, do not contain complement for sensitised ox blood corpuscles. They are both highly specialised secretions. #13. The fluid that collects in a short time after puncture in the anterior chamber of the eye and Blister fluids do contain, such complement. They are both of the nature of transudates from the blood vessels. #14. As showing the highly specialised nature of the secretion in the anterior chamber of the eye, some rabbits, with a blood serum, of very high titre in Immune body against ox blood corpuscles, may have none of this Immune body in even 0.5cc of their aqueous humour). #15. Normal rabbits may be bled to the extent of more than one third of their blood at one sitting, or of more than one half within 18 hours without showing any change in the complement content of their serum for sensitised ox blood corpuscles . #16. If a normal rabbit, whose blood has been ascertained to be free from Immune body against ox blood corpuscles, be injected intravenously with a large amount of ox blood corpuscles - 28cc equivalent to 56cc defibrinated blood - the ox blood corpuscles can be recognised in the rabbit's general circulation until about the third day. At that time there is a critical formation of Immune body, a critical disappearance of the ox blood corpuscles, and a critical haemoglobinuria. contrary to what Sachs found, I did not observe any variation in the complement content for ox blood corpuscles in such an experiment. #17. The infection intravenously into normal rabbits of unsensitised ox blood corpuscles, even in very large quantity, does not produce any diminution of complement. The injection intravenously into normal rabbits, of an amount of sensitised or saturated ox blood corpuscles calculated to be sufficient to use up all the complement in the rabbit's body produces no reduction of the complement, while the injection of four times the calculated amount of such corpuscles into a similar rabbit, produces a scarcely perceptible diminution of the complement. On the other hand, the injection intravenously into rabbits, which have been immunised against ox blood corpuscles, of a quantity of fresh, sensitised, or saturated corpuscles far from sufficient to use up all the calculated amount of complement in the animal's body, markedly reduces the complement content of the animal's blood. Such animals often die rapidly. The possible explanation of both Phenomena may be,that the sudden lysis sets free stromata, which absorb the complement and further block the capillaries of the lung and other organs. #18. If a normal rabbit be injected intraperitoneally with inactivated Immune serum against rabbit corpuscles, obtained by injecting a guinea pig with rabbit corpuscles, this heated immune serum appears to be absorbed into the rabbits bloodyto find complement there free in the blood, to unite with it and to cause extracellular haemolysis of the rabbi'ts red blood corpuscles and intense haemoglobinuria. #19. There is great probability therefore, that complement exists, free in the circulating plasma of the blood, and that, further, the organ, producing complement, must be one of great metabolic activity and of exceptional powers of regeneration. #20. The extirpation of the spleen and of the thyroid in rabbits may be said to cause no variation in the complement content of rabbits' serum. #21. Taking such things in relation, with the positive findings of Nolf, Ehrlich &c., I submit that the liver ought to be considered as a possible seat of origin of complement. #22. When hen corpuscles are injected intravenously into rabbits, the corpuscles tend to accumulate and to be retained in the liver. #23. Such corpuscles are phagocyted to a small degree by the liver cells and Kupfer cells. No evidence was observed for phagocytosis taking place in the spleen or any of the other organs. #24. The liver cells are capable of a wide variation in morphological appearance, possibly corresponding with a similar wide range of metabolic activity and functioning. #25. Taking into consideration the facts exclusive and presumptive accumulated above concerning the seat of origin of Immune body, the facts of the accumulation and retention of hen corpuscles in the liver and then phagocytosis there, and the fact of the great variation possible in the liver cell, I submit that the liver ought to be considered as a possible seat of origin of immune body. #26. To generalise, I would submit the possibility of the formation of antibodies being, in nature, the hypertrophy of a normal physiological process - a process which physiologically deals with overflow from the intestinal tract of material, toxic and non toxic, fluid and particulate, multiplying and non multiplying and which has escaped the process of intestinal digestion to which the bulk of absorbed material is subjected before absorption