Paradoxical popups: Why are they hard to catch?

Even professional baseball players occasionally find it difficult to gracefully approach seemingly routine pop-ups. This paper describes a set of towering pop-ups with trajectories that exhibit cusps and loops near the apex. For a normal fly ball, the horizontal velocity is continuously decreasing due to drag caused by air resistance. But for pop-ups, the Magnus force (the force due to the ball spinning in a moving airflow) is larger than the drag force. In these cases the horizontal velocity decreases in the beginning, like a normal fly ball, but after the apex, the Magnus force accelerates the horizontal motion. We refer to this class of pop-ups as paradoxical because they appear to misinform the typically robust optical control strategies used by fielders and lead to systematic vacillation in running paths, especially when a trajectory terminates near the fielder. In short, some of the dancing around when infielders pursue pop-ups can be well explained as a combination of bizarre trajectories and misguidance by the normally reliable optical control strategy, rather than apparent fielder error. Former major league infielders confirm that our model agrees with their experiences.Comment: 28 pages, 10 figures, sumitted to American Journal of Physic

Short-Timescale monitoring of the X-ray, UV and broad double-peak emission line of the nucleus of NGC 1097

Recent studies have suggested that the short-timescale ($\lesssim7$ days) variability of the broad ($\sim$10,000 km s$^{-1}$) double-peaked H$\alpha$ profile of the LINER nucleus of NGC1097 could be driven by a variable X-ray emission from a central radiatively inefficient accretion flow (RIAF). To test this scenario, we have monitored the NGC1097 nucleus in X-ray and UV continuum with Swift and the H$\alpha$ flux and profile in the optical spectrum using SOAR and Gemini-South from 2012 August to 2013 February. During the monitoring campaign, the H$\alpha$ flux remained at a very low level --- 3 times lower than the maximum flux observed in previous campaigns and showing only limited ($\sim 20\%$) variability. The X-ray variations were small, only $\sim 13\%$ throughout the campaign, while the UV did not show significant variations. We concluded that the timescale of the H$\alpha$ profile variation is close to the sampling interval of the optical observations, which results in only marginal correlation between the X-ray and H$\alpha$ fluxes. We have caught the AGN in NGC1097 in a very low activity state, in which the ionizing source was very weak and capable of ionizing just the innermost part of the gas in the disk. Nonetheless, the data presented here still support the picture in which the gas that emits the broad double-peaked Balmer lines is illuminated/ionized by a source of high-energy photons which is located interior to the inner radius of the line-emitting part of the disk.Comment: The paper contains 14 pages, 7 figures and is accepted for publication at the Astrophysical Journa

Protocols for calibrating multibeam sonar

Development of protocols for calibrating multibeam sonar by means of the standard-target method is documented. Particular systems used in the development work included three that provide the water-column signals, namely the SIMRAD SM2000/90- and 200-kHz sonars and RESON SeaBat 8101 sonar, with operating frequency of 240 kHz. Two facilities were instrumented specifically for the work: a sea well at the Woods Hole Oceanographic Institution and a large, indoor freshwater tank at the University of New Hampshire. Methods for measuring the transfer characteristics of each sonar, with transducers attached, are described and illustrated with measurement results. The principal results, however, are the protocols themselves. These are elaborated for positioning the target, choosing the receiver gain function, quantifying the system stability, mapping the directionality in the plane of the receiving array and in the plane normal to the central axis, measuring the directionality of individual beams, and measuring the nearfield response. General preparations for calibrating multibeam sonars and a method for measuring the receiver response electronically are outlined. Advantages of multibeam sonar calibration and outstanding problems, such as that of validation of the performance of multibeam sonars as configured for use, are mentioned

Liberty Bell Hospital: A Case Study In Employee Information Systems Fraud

Information systems provide an attractive opportunity for dishonest employees in sensitive job positions to develop and implement a fraudulent scheme. Many different types of technical information systems controls help prevent these situations from occurring and can also detect occurrences after they have happened. However, in some cases, employees are able to circumvent critical segregation of duties. In addition, management of a company may override traditional internal controls in order to achieve business objectives. Overriding internal controls can produce an environment that is conducive to fraud.Internal auditors with an information systems specialty can often identify red flags prior to fraudulent acts taking place in the organization. This allows an organization to utilize preventive measures to reduce the likelihood of a fraud occurring. In a specific situation where an information system fraud is suspected, internal auditors are often charged with leading the investigation. This case analyzes an employee fraud involving a breakdown of internal information technology and management controls, falsification of business records, and a lack of segregation of duties. This case is designed for use in either an undergraduate auditing, information systems security, accounting ethics, internal auditing, computer ethics or other related class. Its primary purpose is to introduce students to a very common type of employee fraud and to illustrate how professional guidance can be applied in such a situation. While the case is based on a true situation, all identities have been modified to protect each individuals right to privacy

Reactivity of Zinc Finger Cysteines: Chemical Modifications Within Labile Zinc Fingers in Estrogen Receptor

Estrogen receptor (ER, alpha isoform) is a 67 kDa zinc finger transcription factor that plays a fundamental role in both normal reproductive gland development and breast carcinogenesis, and also represents a critical molecular target for breast cancer therapy. We are investigating the structural consequences of chemical exposures thought to modify essential zinc finger cysteine residues in human ER. The current study employs mass spectrometry to probe ER zinc finger structural changes induced by a redox-reactive vitamin K3 analog, menadione; a commonly used cysteine alkylator, iodoacetic acid; and a thiol alkylating fluorophore, monobromobimane. Although they are slower to react, the sterically bulkier reagents, monobromobimane and menadione, effectively alkylate the most susceptible ER zinc finger cysteine sulfhydryl groups. Menadione arylation results first in Michael addition of the hydroquinone followed by rapid oxidation to the corresponding quinone, evidenced by a 2 Da mass loss per cysteine residue. Mass spectrometric analysis performed under MALDI conditions reveals both hydroquinone and quinone forms of arylated menadione, whereas only the quinone product is detectable under ESI conditions. Tandem mass spectrometry of a synthetic peptide encompassing the C-terminal half of the structurally more labile second zinc finger of ER (ZnF2B) demonstrates that the two nucleophilic thiols in ZnF2B (Cys-237, Cys-240) are not chemically equivalent in their reactivity to bromobimane or menadione, consistent with their unequal positioning near basic amino acids that affect thiol pKa, thereby rendering Cys-240 more reactive than Cys-237. These findings demonstrate important differential susceptibility of ER zinc finger cysteine residues to thiol reactions

Predicting Raccoon, Procyon lotor, Occurrence Through the Use of Microhabitat Variables

Recent increases in Raccoon (Procyon lotor) abundance have been implicated for decreased nesting success of songbirds and transmission of rabies. Understanding the relationship between occurrence and microhabitat factors should be helpful in managing this species, though our current understanding of this relationship is inadequate. Therefore, we conducted a study in western Tennessee during 2000–2002 to determine this association. Occurrence (capture) data were assessed from results of live trapping at 176 and 112 trap sites during winter and summer, respectively, at three sites. A maximum of 26 habitat variables were measured at each trap location; all grids were combined for statistical analyses to account for varying relationships between occurrence and microhabitat factors across different landscapes. Univariate and stepwise logistic-regression analyses were used to assess associations among microhabitat variables and occurrence. Resulting models were validated through the jackknife procedure. Predictive equations were constructed from logistic-regression models to compute capture probabilities. Univariate analyses yielded numerous significant variables with those representing forest characteristics and proximity to water generally the most significant. Strong concordance was observed between winter and summer seasons for most variables though several differed (number of large hardwood snags, ground dens, and plant food species, distance to potential water and roads). Such temporal variability was expected due to seasonal differences in habitat components and biological needs of Raccoons. Variables included in derived models were similar to those scoring highest in univariate analyses; classification rates for models (winter = 72%; summer = 78%) were among the highest recorded for generalist species. By accounting for landscape attributes and replicating across sites, more accurate and useful models were developed. Such models should provide the information required to effectively manage this species

A Survey on the Interplay between Software Engineering and Systems Engineering during SoS Architecting

Background: The Systems Engineering and Software Engineering disciplines are highly intertwined in most modern Systems of Systems (SoS), and particularly so in industries such as defense, transportation, energy and health care. However, the combination of these disciplines during the architecting of SoS seems to be especially challenging; the literature suggests that major integration and operational issues are often linked to ambiguities and gaps between system-level and software-level architectures. Aims: The objective of this paper is to empirically investigate: 1) the state of practice on the interplay between these two disciplines in the architecting process of systems with SoS characteristics; 2) the problems perceived due to this interplay during said architecting process; and 3) the problems arising due to the particular characteristics of SoS systems. Method: We conducted a questionnaire-based online survey among practitioners from industries in the aforementioned domains, having a background on Systems Engineering, Software Engineering or both, and experience in the architecting of systems with SoS characteristics. The survey combined multiple-choice and open-ended questions, and the data collected from the 60 respondents were analyzed using quantitative and qualitative methods. Results: We found that although in most cases the software architecting process is governed by system-level requirements, the way requirements were specified by systems engineers, and the lack of domain-knowledge of software engineers, often lead to misinterpretations at software level. Furthermore, we found that unclear and/or incomplete specifications could be a common cause of technical debt in SoS projects, which is caused, in part, by insufficient interface definitions. It also appears that while the SoS concept has been adopted by some practitioners in the field, the same is not true about the existing and growing body of knowledge on the subject in Software Engineering resulting in recurring problems with system integration. Finally, while not directly related to the interplay of the two disciplines, the survey also indicates that low-level hardware components, despite being identified as the root cause of undesired emergent behavior, are often not considered when modeling or simulating the system. Conclusions: The survey indicates the need for tighter collaboration between the two disciplines, structured around concrete guidelines and practices for reconciling their differences. A number of open issues identified by this study require further investigation