First evidence of grass carp recruitment in the Great Lakes Basin

We use aging techniques, ploidy analysis, and otolith microchemistry to assess whether four grass carp Ctenopharyngodon idella captured from the Sandusky River, Ohio were the result of natural reproduction within the Lake Erie Basin. All four fish were of age 1 +. Multiple lines of evidence indicate that these fish were not aquaculture-reared and that they were most likely the result of successful reproduction in the Sandusky River. First, at least two of the fish were diploid; diploid grass carp cannot legally be released in the Great Lakes Basin. Second, strontium:calcium (Sr:Ca) ratios were elevated in all four grass carp from the Sandusky River, with elevated Sr:Ca ratios throughout the otolith transect, compared to grass carp from Missouri and Arkansas ponds. This reflects the high Sr:Ca ratio of the Sandusky River, and indicates that these fish lived in a high-strontium environment throughout their entire lives. Third, Sandusky River fish were higher in Sr:Ca ratio variability than fish from ponds, reflecting the high but spatially and temporally variable strontium concentrations of southwestern Lake Erie tributaries, and not the stable environment of pond aquaculture. Fourth, Sr:Ca ratios in the grass carp from the Sandusky River were lower in their 2011 growth increment (a high water year) than the 2012 growth increment (a low water year), reflecting the observed inverse relationship between discharge and strontium concentration in these rivers. We conclude that these four grass carp captured from the Sandusky River are most likely the result of natural reproduction within the Lake Erie Basin.     

On the Behavior of True and False

Uzquiano (Analysis 70:39–44, 2010) showed that the Hardest Logic Puzzle Ever (HLPE) [in its amended form due to Rabern and Rabern (Analysis 68:105–112, 2008)] has a solution in only two questions. Uzquiano concludes his paper by noting that his solution strategy naturally suggests a harder variation of the puzzle which, as he remarks, he does not know how to solve in two questions. Wheeler and Barahona (J Philos Logic, to appear, 2011) formulated a three question solution to Uzquiano’s puzzle and gave an information theoretic argument to establish that a two question solution for Uzquiano’s puzzle does not exist. However, their argument crucially relies on a certain conception of what it means to answer self-referential yes–no questions truly and falsely. We propose an alternative such conception which, as we show, allows one to solve Uzquiano’s puzzle in two questions. The solution strategy adopted suggests an even harder variation of Uzquiano’s puzzle which, as we will show, can also be solved in two questions. Just as all previous solutions to versions of HLPE, our solution is presented informally. The second part of the paper investigates the prospects of formally representing solutions to HLPE by exploiting theories of truth.     

A method to align the coordinate system of accelerometers to the axes of a human body: The depitch algorithm

One of the key problems in accelerometry based gait analyses is that it may not be possible to attach an accelerometer to the lower trunk so that its axes are perfectly aligned to the axes of the subject. In this paper we will present an algorithm that was designed to virtually align the axes of the accelerometer to the axes of the subject during walking sections. This algorithm is based on a physically reasonable approach and built for measurements in unsupervised settings, where the test persons are applying the sensors by themselves. For evaluation purposes we conducted a study with 6 healthy subjects and measured their gait with a manually aligned and a skewed accelerometer attached to the subject's lower trunk. After applying the algorithm the intra-axis correlation of both sensors was on average 0.89±0.1 with a mean absolute error of 0.05g. We concluded that the algorithm was able to adjust the skewed sensor node virtually to the coordinate system of the subject.     

Three tokens in Herman’s algorithm

Herman’s algorithm is a synchronous randomized protocol for achieving self-stabilization in a token ring consisting of N processes. The interaction of tokens makes the dynamics of the protocol very difficult to analyze. In this paper we study the distribution of the time to stabilization, assuming that there are three tokens in the initial configuration. We show for arbitrary N and for an arbitrary timeout t that the probability of stabilization within time t is minimized by choosing as the initial three-token configuration the configuration in which the tokens are placed equidistantly on the ring. Our result strengthens a corollary of a theorem of McIver and Morgan (Inf. Process Lett. 94(2): 79–84, 2005), which states that the expected stabilization time is minimized by the equidistant configuration.     

Reduced order optimization for model predictive control using principal control moves

In order to reduce the computational complexity of model predictive control (MPC) a proper input signal parametrization is proposed in this paper which significantly reduces the number of decision variables. This parametrization can be based on either measured data from closed-loop operation or simulation data. The snapshots of representative time domain data for all manipulated variables are projected on an orthonormal basis by a Karhunen-Loeve transformation. These significant features (termed principal control moves, PCM) can be reduced utilizing an analytic criterion for performance degradation. Furthermore, a stability analysis of the proposed method is given. Considerations on the identification of the PCM are made and another criterion is given for a sufficient selection of PCM. It is shown by an example of an industrial drying process that a strong reduction in the order of the optimization is possible while retaining a high performance level.     

Numerical simulation of hypervelocity impact on CFRP/Al HC SP spacecraft structures causing penetration and fragment ejection

A representative carbon fiber reinforced plastic/aluminum honeycomb sandwich panel (CFRP/Al HC SP) spacecraft structure has been modeled in the hydrocode AUTODYN using the state-of-the-art ADAMMO material model [Riedel W, Harwick W, White D, Clegg R. Advanced material damage models for numerical simulation codes. ESA CR(P) 4397, 2003] to study the performance of the structure during impact events that cause perforation and fragment ejection. A new procedure combining a series of existing theoretical methods has been developed and applied to derive a full set of coarse material data. The data set has been implemented in AUTODYN, and the results of the numerical simulation have been compared to experimental impact test data. For impact tests performed near the structural ballistic limit, quantitatively accurate results were obtained over a range of impact velocities and angles. A further increase in the projectile size resulted in significant destruction of the sandwich panel front face-sheet and diversion from the experimental damage measurements. Inspection of the numerical model has shown non-localized propagation of inter-laminar delaminations, possibly caused by an under-prediction of the laminate dynamic inter-laminar tensile strength. The effects of the delamination propagation occur over an extended time scale and were not found to affect the state and trends of the fragment cloud ejected into the satellite interior. Accordingly, experimental trends of fragment cloud dispersion have been qualitatively reproduced.     

Creating Space: The Fourfold Dynamics of Potential Space.

Winnicott conceived of potential space primarily in terms of the vicissitudes of illusion and reality. Loosened from its ties to illusion and reality, potential space is depicted in terms of 4 interrelated, dialectical processes (surrender-generation, recognition-negation, care-quiescence, and disruption-repair), which can be found, in part, in Winnicott's formulations. Reformulating potential space in terms of these fourfold pairs captures the complexity and paradox of the presence and absence of self-states in successful and failed developmental and psychoanalytic interactions. In addition, these 4 interpersonal dynamics more adequately extend the concept of potential space to all phases of human life. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Prosocial Emotions and Helping: The Moderating Role of Group Membership.

In this article, the authors introduce and test a group-level perspective on the role of empathy and interpersonal attraction in helping. In line with our predictions, Study 1, a longitudinal field study of 166 AIDS volunteers, confirmed that empathy was a stronger predictor of helping when the recipient of assistance was an in-group member than when that person was an out-group member. Also as hypothesized, attraction was a stronger predictor of helping when the recipient was an out-group member than when that person was an in-group member. Study 2 replicated and further extended these results in a laboratory experiment on spontaneous helping of a person with hepatitis. Strengthening the validity of the findings, in both studies the effects of empathy and attraction held up even when the authors statistically controlled for potential alternative predictors of helping. The theoretical and practical implications of these findings for helping in intergroup contexts are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Two views on security software liability. Let the legal system decide

Rather than use the product liability screwdriver as a chisel, why not consider a package of more effective tools. Corporations and individuals that market software despite knowledge of software security flaws should face criminal prosecution as well as civil lawsuits with punitive damages. Perhaps bounties should be available for the first to discover and establish the existence of a security flaw. Publishers should be required to post to the Web and otherwise publicize promptly patch availability. The software equivalent of an Underwriters Laboratories should establish and constantly improve security-related standards and testing protocols. It should be made readily apparent whether a program has passed and at what level. Prospective customers should be educated and encouraged to insist on software that has passed. Stronger software security is important. Software developers and publishers must do better. But product liability is not the right legal tool for the job.     

Key principles for user-centred systems design

The concept of user-centred systems design (UCSD) has no agreed upon definition. Consequently, there is a great variety in the ways it is applied, which may lead to poor quality and poor usability in the resulting systems, as well as misconceptions about the effectiveness of UCSD. The purpose of this paper is to propose a definition of UCSD. We have identified 12 key principles for the adoption of a user-centred development process, principles that are based on existing theory, as well as research in and experiences from a large number of software development projects. The initial set of principles were applied and evaluated in a case study and modified accordingly. These principles can be used to communicate the nature of UCSD, evaluate a development process or develop systems development processes that support a user-centred approach. We also suggest activity lists and some tools for applying UCSD.