Altruism, Markets, and Organ Procurement

For decades, the dominant view among biomedical ethicists, transplantation professionals, and the public at large has been that altruism, not financial considerations, should motivate organ donors. Proposals to compensate sources of transplantable organs or their survivors, although endorsed by a number of economists and legal scholars, have been denounced as unethical and impracticable. Organ transplantation is said to belong to the world of gift, as distinct from the market realm. Paying for organs would inject commerce into a sphere where market values have no place and would transform a system based on generosity and civic spirit into one of antiseptic, bargained-for exchanges. Here, Mahoney discusses a brief history of the restriction on payments to sources of transplantable organs. She then turn to the arguments commonly advanced against compensating organ sources and explain how they are grounded in beliefs that range from the highly contestable to the demonstrably wrong. Furthermore, she examines the most popular compensation proposals, and offering preliminary assessments of their promise and feasibility. She also concludes with some thoughts about the relationship between altruism and self-interest

Tree decompositions and social graphs

Recent work has established that large informatics graphs such as social and information networks have non-trivial tree-like structure when viewed at moderate size scales. Here, we present results from the first detailed empirical evaluation of the use of tree decomposition (TD) heuristics for structure identification and extraction in social graphs. Although TDs have historically been used in structural graph theory and scientific computing, we show that---even with existing TD heuristics developed for those very different areas---TD methods can identify interesting structure in a wide range of realistic informatics graphs. Our main contributions are the following: we show that TD methods can identify structures that correlate strongly with the core-periphery structure of realistic networks, even when using simple greedy heuristics; we show that the peripheral bags of these TDs correlate well with low-conductance communities (when they exist) found using local spectral computations; and we show that several types of large-scale "ground-truth" communities, defined by demographic metadata on the nodes of the network, are well-localized in the large-scale and/or peripheral structures of the TDs. Our other main contributions are the following: we provide detailed empirical results for TD heuristics on toy and synthetic networks to establish a baseline to understand better the behavior of the heuristics on more complex real-world networks; and we prove a theorem providing formal justification for the intuition that the only two impediments to low-distortion hyperbolic embedding are high tree-width and long geodesic cycles. Our results suggest future directions for improved TD heuristics that are more appropriate for realistic social graphs.Comment: v2 has 44 pages, 21 figures, 7 tables, 107 references. To appear in Internet Mathematic

A pilot study examining garment severance damage caused by a trained sharp-weapon user

The pilot study summarized in this paper aimed to raise awareness of a gap that exists in the forensic textile science literature about damage caused to clothing by trained sharp-weapon users. A male trained in the Filipino martial arts discipline of Eskrima performed attack techniques on a physical model of a male torso covered with a 97% cotton/3% elastane knitted T-shirt, that is, a garment commonly worn by males. Fabric severance appearance created by three different, but commonly available, knives was evaluated. High-speed video was used to capture each attack. After each attack the resulting damage to the garment was assessed. This pilot study highlighted differences in severances associated with weapon selection, that is, not all knives resulted in similar patterns of textile damage. In addition, a mixture of stab and slash severances were observed. The findings demonstrated the possible misinterpretation of textile damage under these circumstances compared to damage patterns reported in the existing forensic textile science literature for more commonly occurring knife attacks (i.e. stabbings)

Adolescent physical self-perceptions, sport/exercise and lifestyle physical activity

Purpose – Domain and sub-domain physical self-perceptions have been associated with adolescent moderate intensity physical activity although the association with different types of adolescent moderate intensity physical activity remains unclear. This study seeks to examine the relationship between personal self-perceptions and adolescent sport/exercise and lifestyle moderate intensity physical activity frequency. Design/methodology/approach – A total of 122, 13-to-14 year-old, English adolescents from Leeds, West Yorkshire (58 boys and 64 girls) had their personal self-perceptions, sport/exercise and lifestyle moderate intensity physical activity assessed. Findings – No significant positive relationships were found between boys' personal self-perceptions and lifestyle moderate intensity physical activity. However, a range of weak (r?=?0.34-0.42) but significant relationships (p?<?0.01) were found between personal self perceptions and boys' sport/exercise frequency. In contrast, only perceptions of strength competence were significantly related to girls' sport/exercise frequencies (r?=?0.28; p?<?0.05), while all personal self perceptions scales were significantly related to girls' lifestyle moderate intensity physical activity (r?=?0.26-0.32; p?<?0.05). Research limitations/implications – The use of correlation analyses by this study placed limitations on the extent to which cause-effect relationships were established. Furthermore, girls' sport/exercise was poorly distributed, which may have led to the non-significant relationship found between this activity type and personal self-perceptions. The presence of a significant relationship between these two variables should therefore not be discounted. Originality/value – This study seems to be the first to investigate and identify variations in the personal self-perceptions – moderate intensity physical activity relationship relative to activity type. Although more research is required, findings have implications for practitioners aiming to tailor physical activity interventions to this group and researchers aiming to match specific correlates to different types of adolescent physical activity

Report of the x ray and gamma ray sensors panel

Overall five major areas of technology are recommended for development in order to meet the science requirements of the Astrotech 21 mission set. These are: detectors for high resolution gamma ray spectroscopy, cryogenic detectors for improved x ray spectral and spatial resolution, advanced x ray charge coupled devices (CCDs) for higher energy resolution and larger format, extension to higher energies, liquid and solid position sensitive detectors for improving stopping power in the energy range 5 to 500 keV and 0.2 to 2 MeV. Development plans designed to achieve the desired capabilities on the time scales required by the technology freeze dates have been recommended in each of these areas

Dispersive Readout of a Few-Electron Double Quantum Dot with Fast rf Gate-Sensors

We report the dispersive charge-state readout of a double quantum dot in the few-electron regime using the in situ gate electrodes as sensitive detectors. We benchmark this gate-sensing technique against the well established quantum point contact (QPC) charge detector and find comparable performance with a bandwidth of 10 MHz and an equivalent charge sensitivity of 6.3 x 10-3 e/ \sqrt Hz. Dispersive gate-sensing alleviates the burden of separate charge detectors for quantum dot systems and promises to enable readout of qubits in scaled-up arrays

On-Chip Microwave Quantum Hall Circulator

Circulators are non-reciprocal circuit elements integral to technologies including radar systems, microwave communication transceivers, and the readout of quantum information devices. Their non-reciprocity arises from the interference of microwaves over the centimetre-scale of the signal wavelength in the presence of bulky magnetic media that break time-reversal symmetry. Here we realize a completely passive on-chip microwave circulator with size one-thousandth the wavelength by exploiting the chiral, slow-light response of a 2-dimensional electron gas (2DEG) in the quantum Hall regime. For an integrated GaAs device with 330 um diameter and 1 GHz centre frequency, a non-reciprocity of 25 dB is observed over a 50 MHz bandwidth. Furthermore, the direction of circulation can be selected dynamically by varying the magnetic field, an aspect that may enable reconfigurable passive routing of microwave signals on-chip