Book Review: Cannabis Policy: Moving Beyond Stalemate by Robin Room, Benedikt Fisher, Wayne Hill, Simon Lenton, & Peter Reuter.

Book Review: Cannabis Policy: Moving Beyond Stalemate by Robin Room, Benedikt Fisher, Wayne Hill, Simon Lenton, & Peter Reuter

Investigating Student Mental Models at the Intersection of Mathematics and Physical Reasoning in Physics

A significant challenge in learning science and mathematics is coordinating different types of mental models, such as mathematical and physical mental models, that represent different aspects of a given phenomenon. This challenge is illustrated in the present study, in which we observed a small number of college students reasoning about forces as both physical and mathematical quantities as they reasoned about a physical system. Using video analysis of the students’ gesture and as they reasoned qualitatively and mathematically about the system, we documented the construction and coordination of participants’ mental models. We found that participants constructed mathematical mental models as imagined lines uniquely to physical mental models as imagined pulls. Moreover, students rarely exhibited the coordination of these two mental models. These findings suggest that instructors that they cannot assume that students generate models, even circumstances designed to support them

TRAIL induces nuclear translocation and chromatin localization of TRAIL death receptors

Binding of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) to the plasma membrane TRAIL-R1/-R2 selectively kills tumor cells. This discovery led to evaluation of TRAIL-R1/-R2 as targets for anti-cancer therapy, yet the corresponding clinical trials were disappointing. Meanwhile, it emerged that many cancer cells are TRAIL-resistant and that TRAIL-R1/R2-triggering may lead to tumor-promoting effects. Intriguingly, recent studies uncovered specific functions of long ignored intracellular TRAIL-R1/-R2, with tumor-promoting functions of nuclear (n)TRAIL-R2 as the regulator of let-7-maturation. As nuclear trafficking of TRAIL-Rs is not well understood, we addressed this issue in our present study. Cell surface biotinylation and tracking of biotinylated proteins in intracellular compartments revealed that nTRAIL-Rs originate from the plasma membrane. Nuclear TRAIL-Rs-trafficking is a fast process, requiring clathrin-dependent endocytosis and it is TRAIL-dependent. Immunoprecipitation and immunofluorescence approaches revealed an interaction of nTRAIL-R2 with the nucleo-cytoplasmic shuttle protein Exportin-1/CRM-1. Mutation of a putative nuclear export sequence (NES) in TRAIL-R2 or the inhibition of CRM-1 by Leptomycin-B resulted in the nuclear accumulation of TRAIL-R2. In addition, TRAIL-R1 and TRAIL-R2 constitutively localize to chromatin, which is strongly enhanced by TRAIL-treatment. Our data highlight the novel role for surface-activated TRAIL-Rs by direct trafficking and signaling into the nucleus, a previously unknown signaling principle for cell surface receptors that belong to the TNF-superfamily

New association between red wood ant species (Formica rufa group) and the myrmecophilic spiders Mastigusa arietina and Thyreosthenius biovatus

Ants belonging to the Formica rufa species group, counting 10 representatives in Europe, are often referred to as red wood ants (RWAs). These dominant, mound building species are known to host in their nests an extremely diverse fauna of associated myrmecophilic arthropods, among which are the two W-Palaearctic spider species Mastigusa arietina (Thorell 1871) and Thyreosthenius biovatus (O. Pickard-Cambridge 1875). The actual host range of these spiders within the Formica rufa group is little known, due to the taxonomic uncertainties that have characterized RWAs in the past. We conducted a large-scale survey for assessing the occurrence of both spider species in association with different RWAs, with a focus on an accurate identification of the ant species. We recorded co-occurrence data for 5 European representatives of the Formica rufa group, and we reported for the first time on the co-occurrence of M. arietina with Formica aquilonia Yarrow 1955, Formica lugubris Zetterstedt 1838 and Formica paralugubris Seifert 1996, and of T. biovatus with F. aquilonia. We found no association between the rate of presence/absence of the two spiders and host ant species or sampling localities, which suggests a non-selective exploitation of RWA hosts by the two myrmecophilic spiders

First record of the genus Thyreosthenius (Araneae: Linyphiidae) from the Iberian Peninsula with notes on the host preference of the myrmecophilic T. biovatus

The presence of the spider genus Thyreosthenius Simon, 1884 (Linyphiidae) is for the first time confirmed in the Iberian Peninsula with an observation of the myrmecophile species T. biovatus (O. Pickard Cambridge, 1875). Four adult females and two sub-adult male specimens were collected inside mound nests belonging to the red wood ant species Formica lugubris Zetterstedt, 1838 in the Aragon and Catalonia regions of Spain. This represents the second known record of an occurrence of T. biovatus in association with F. lugubris, and the first for Continental Europe. In addition, the existing information on the host preference of this species is reviewed and discussed in relation to the new data from the Spanish Pyrenees

Effects of Cortical FoxP1 Knockdowns on Learned Song Preference in Female Zebra Finches

The search for molecular underpinnings of human vocal communication has focused on genes encoding forkhead-box transcription factors, as rare disruptions of FOXP1, FOXP2, and FOXP4 have been linked to disorders involving speech and language deficits. In male songbirds, an animal model for vocal learning, experimentally altered expression levels of these transcription factors impair song production learning. The relative contributions of auditory processing, motor function or auditory-motor integration to the deficits observed after different FoxP manipulations in songbirds are unknown. To examine the potential effects on auditory learning and development, we focused on female zebra finches (Taeniopygia guttata) that do not sing but develop song memories, which can be assayed in operant preference tests. We tested whether the relatively high levels of FoxP1 expression in forebrain areas implicated in female song preference learning are crucial for the development and/or maintenance of this behavior. Juvenile and adult female zebra finches received FoxP1 knockdowns targeted to HVC (proper name) or to the caudomedial mesopallium (CMM). Irrespective of target site and whether the knockdown took place before (juveniles) or after (adults) the sensitive phase for song memorization, all groups preferred their tutor’s song. However, adult females with FoxP1 knockdowns targeted at HVC showed weaker motivation to hear song and weaker song preferences than sham-treated controls, while no such differences were observed after knockdowns in CMM or in juveniles. In summary, FoxP1 knockdowns in the cortical song nucleus HVC were not associated with impaired tutor song memory but reduced motivation to actively request tutor songs

Mode regularization of the susy sphaleron and kink: zero modes and discrete gauge symmetry

To obtain the one-loop corrections to the mass of a kink by mode regularization, one may take one-half the result for the mass of a widely separated kink-antikink (or sphaleron) system, where the two bosonic zero modes count as two degrees of freedom, but the two fermionic zero modes as only one degree of freedom in the sums over modes. For a single kink, there is one bosonic zero mode degree of freedom, but it is necessary to average over four sets of fermionic boundary conditions in order (i) to preserve the fermionic Z$_2$ gauge invariance $\psi \to -\psi$, (ii) to satisfy the basic principle of mode regularization that the boundary conditions in the trivial and the kink sector should be the same, (iii) in order that the energy stored at the boundaries cancels and (iv) to avoid obtaining a finite, uniformly distributed energy which would violate cluster decomposition. The average number of fermionic zero-energy degrees of freedom in the presence of the kink is then indeed 1/2. For boundary conditions leading to only one fermionic zero-energy solution, the Z$_2$ gauge invariance identifies two seemingly distinct `vacua' as the same physical ground state, and the single fermionic zero-energy solution does not correspond to a degree of freedom. Other boundary conditions lead to two spatially separated $\omega \sim 0$ solutions, corresponding to one (spatially delocalized) degree of freedom. This nonlocality is consistent with the principle of cluster decomposition for correlators of observables.Comment: 32 pages, 5 figure