The design and construction of a pneumatic harvester for crimson clover seed

The current problem in harvesting crimson clover seed is not new. As early as 1915, Mr. J. M. Westgate recognized the shattering tendency of the plant as the principal drawback in harvesting the seed crop. The problem is to reduce or to eliminate the possibility of an appreciable loss of seed caused by shattering both before and during the harvesting process. The problem can be approached in two ways. First, a shatter-resistant strain of crimson clover, which would be well adapted to direct combine harvesting, might be developed through plant breeding; this method of approach, however, would probably require several years of breeding and might even then not be successful. Secondly, as this study proposes to show, a satisfactory solution to the problem can be reached by making a change in the harvesting machinery. The purpose of this study is to arrive at a design for an attachment to be used on a combine. The function of this attachment will be to recover shattered crimson clover seed during the direct combining process and to deliver the recovered seed to the threshing cylinder of the combine. In an effort to evaluate the design, an experimental attachment has been constructed and tested both in the laboratory and in the field

Execution Integrity with In-Place Encryption

Instruction set randomization (ISR) was initially proposed with the main goal of countering code-injection attacks. However, ISR seems to have lost its appeal since code-injection attacks became less attractive because protection mechanisms such as data execution prevention (DEP) as well as code-reuse attacks became more prevalent. In this paper, we show that ISR can be extended to also protect against code-reuse attacks while at the same time offering security guarantees similar to those of software diversity, control-flow integrity, and information hiding. We present Scylla, a scheme that deploys a new technique for in-place code encryption to hide the code layout of a randomized binary, and restricts the control flow to a benign execution path. This allows us to i) implicitly restrict control-flow targets to basic block entries without requiring the extraction of a control-flow graph, ii) achieve execution integrity within legitimate basic blocks, and iii) hide the underlying code layout under malicious read access to the program. Our analysis demonstrates that Scylla is capable of preventing state-of-the-art attacks such as just-in-time return-oriented programming (JIT-ROP) and crash-resistant oriented programming (CROP). We extensively evaluate our prototype implementation of Scylla and show feasible performance overhead. We also provide details on how this overhead can be significantly reduced with dedicated hardware support

More than a passive interest

Abstract The defeat of the Dyer anti-lynching bill in 1922 was a turning point in relations between black Americans and the Republican Party. Little is understood, however, about the role played in the debates by President Warren Harding. This article contends that Harding's conflicted approach to presidential leadership caused him to mishandle the bill. The President's inability to choose between restrained 'whig' leadership and a more active 'stewardship' role resulted in an unstable executive style. The Dyer bill's failure was affected by this dilemma as black hopes were alternately raised and dashed by Harding's indecision. The bitterness of the bill's ultimate defeat was thus heightened, with severe consequences for the Republican party's long term electoral relationship with black voters

Whats Good for the Goose is Bad for the Gander: Negative Political Advertising, Partisanship and Turnout

This study examines citizens’ perceptions of fairness and legitimacy in political advertising. Using focus groups, an original national survey, and data on election 2000, as well as drawing on results from a replication of the national survey in 2004, we characterize political ads from the citizen’s perspective. We then turn to the impact of ‘‘negative’’ advertising on voter turnout. Like several studies, we find circumstances under which turnout can be increased by negative ad criticisms. However, we show that this general result is only part of the story. Drawing on research in political psychology, we suggest that voters are ‘‘motivated processors’’ of advertising claims; as such, they evaluate the fairness of an ad according to their partisan predispositions. We show that when partisans perceive the criticisms of their own party’s candidate to be fair, they are less likely to say they will vote. As a result, we find that negative advertising not only may affect the total turnout in an election but also has an important and varying impact on the composition of the electorate

The Muzzled Dog That Didn’t Bark: Charters and the Behavioral Response of D.C. Public Schools

As of the 2006-2007 school year, 19,733 students attended charter schools in the District of Columbia, representing over a quarter of the District’s total public school student population and one of the largest charter school markets in the country.1 It is under such circumstances, some suggest, that choice will spur competition, ultimately leading to the improvement of public education. Yet, surprisingly little research has evaluated the behavioral response of public schools in D.C. to this source of competition. Most research to date on school choice in D.C. and elsewhere focuses on the largely positive “participant effects” that school choice programs have on choosers. By looking at the issue from the ground level of one of the most choice-prevalent districts in the United States, we seek to closely examine the causal dynamics of “systemic effects” induced by competition from within the D.C. education establishment. Our study consists of a series of interviews, focus groups, and surveys along three levels: District elites, principals, and teachers

Morehead State University Student Members of the American Chemical Society

https://scholarworks.moreheadstate.edu/student_scholarship_posters/1217/thumbnail.jp

PDNPulse: Sensing PCB Anomaly with the Intrinsic Power Delivery Network

The ubiquitous presence of printed circuit boards (PCBs) in modern electronic systems and embedded devices makes their integrity a top security concern. To take advantage of the economies of scale, today's PCB design and manufacturing are often performed by suppliers around the globe, exposing them to many security vulnerabilities along the segmented PCB supply chain. Moreover, the increasing complexity of the PCB designs also leaves ample room for numerous sneaky board-level attacks to be implemented throughout each stage of a PCB's lifetime, threatening many electronic devices. In this paper, we propose PDNPulse, a power delivery network (PDN) based PCB anomaly detection framework that can identify a wide spectrum of board-level malicious modifications. PDNPulse leverages the fact that the PDN's characteristics are inevitably affected by modifications to the PCB, no matter how minuscule. By detecting changes to the PDN impedance profile and using the Frechet distance-based anomaly detection algorithms, PDNPulse can robustly and successfully discern malicious modifications across the system. Using PDNPulse, we conduct extensive experiments on seven commercial-off-the-shelf PCBs, covering different design scales, different threat models, and seven different anomaly types. The results confirm that PDNPulse creates an effective security asymmetry between attack and defense

GW Librae: Still Hot Eight Years Post-Outburst

We report continued Hubble Space Telescope (HST) ultraviolet spectra and ground-based optical photometry and spectroscopy of GW Librae eight years after its largest known dwarf nova outburst in 2007. This represents the longest cooling timescale measured for any dwarf nova. The spectra reveal that the white dwarf still remains about 3000 K hotter than its quiescent value. Both ultraviolet and optical light curves show a short period of 364-373 s, similar to one of the non-radial pulsation periods present for years prior to the outburst, and with a similar large UV/optical amplitude ratio. A large modulation at a period of 2 h (also similar to that observed prior to outburst) is present in the optical data preceding and during the HST observations, but the satellite observation intervals did not cover the peaks of the optical modulation so it is not possible to determine its corresponding UV amplitude. The similarity of the short and long periods to quiescent values implies the pulsating, fast spinning white dwarf in GW Lib may finally be nearing its quiescent configuration.Comment: 6 figures, accepted in A

Laterally Propagating Detonations in Thin Helium Layers on Accreting White Dwarfs

Theoretical work has shown that intermediate mass (0.01Msun<M_He<0.1Msun) Helium shells will unstably ignite on the accreting white dwarf (WD) in an AM CVn binary. For more massive (M>0.8Msun) WDs, these helium shells can be dense enough (5x10^5 g/cc) that the convectively burning region runs away on a timescale comparable to the sound travel time across the shell; raising the possibility for an explosive outcome. The nature of the explosion (i.e. deflagration or detonation) remains ambiguous. In the case of detonation, this causes a laterally propagating front whose properties in these geometrically thin and low density shells we begin to study here. Our calculations show that the radial expansion time of <0.1 s leads to incomplete helium burning, in agreement with recent work by Sim and collaborators, but that the nuclear energy released is still adequate to realize a self-sustaining detonation propagating laterally at slower than the Chapman-Jouguet speed. Our simulations resolve the subsonic region behind the front and are consistent with a direct computation of the reaction structure from the shock strength. The ashes are typically He rich, and consist of predominantly Ti-44, Cr-48, along with a small amount of Fe-52, with very little Ni-56 and with significant Ca-40 in carbon-enriched layers. If this helium detonation results in a Type Ia Supernova, its spectral signatures would appear for the first few days after explosion. (abridged)Comment: 7 pages, 5 figure, accepted to the Astrophysical Journa