1,3,4,6-Tetramethyl-1,4-dihydro-1,2,4,5-tetrazine, C_6H_(12)N_4

M_r =140∙19, monoclinic, P2_1/n, a = 10∙612(3), b=6∙820(1), c= 10∙975 (2) Å, β=95∙31(2)°, V=790.9(5) Å^3, Z=4, D_m=1.13(5) (flotation), D_x = 1∙177 g cm^(-3), Mo Kα, λ = 0.71073 Å, μ= 0.848 cm^(-1), F(000) = 304, T= 295 K, R = 0∙077 for 704 observed reflections. This potentially antiaromatic or homoaromatic ring system has a flattened boat conformation with both N-methyls in equatorial positions. Bond angles and distances (excluding H's) predicted to be symmetry equivalent exhibit variations of 0.002-0.014 Å and 0.0-2.0°. Substantial delocalization of the electron lone pairs of N(1) and N(4) is found

The State of the IS Academic Discipline in Pacific Asia: Methodological Learnings

This is the last in a series of nine papers making up a special issue of Communications of the AIS (CAIS) titled The State of the Information Systems Academic Discipline in Pacific Asia (IS-in-PA). This paper reports on knowledge gleaned from the conduct of the sub-studies that comprise the IS-in PA project. In particular, there is analysis of the specific research artifacts developed for the individual sub-studies reported in this special edition. It is proposed that the methodological learnings derived from this project will be of benefit in the replication and extension of this project to other regions of the world. The paper addresses a key aim of the IS-in-PA, involving the development and application of a process of evidence collection and review transferable to other studies tracking diffusion of the IS discipline

Modelling the mechanoreceptor’s dynamic behaviour

All sensory receptors adapt, i.e. they constantly adjust their sensitivity to external stimuli to match the current demands of the natural environment. Electrophysiological responses of sensory receptors from widely different modalities seem to exhibit common features related to adaptation, and these features can be used to examine the underlying sensory transduction mechanisms. Among the principal senses, mechanosensation remains the least understood at the cellular level. To gain greater insights into mechanosensory signalling, we investigated if mechanosensation displayed adaptive dynamics that could be explained by similar biophysical mechanisms in other sensory modalities. To do this, we adapted a fly photoreceptor model to describe the primary transduction process for a stretch-sensitive mechanoreceptor, taking into account the viscoelastic properties of the accessory muscle fibres and the biophysical properties of known mechanosensitive channels (MSCs). The model's output is in remarkable agreement with the electrical properties of a primary ending in an isolated decapsulated spindle; ramp-and-hold stretch evokes a characteristic pattern of potential change, consisting of a large dynamic depolarization during the ramp phase and a smaller static depolarization during the hold phase. The initial dynamic component is likely to be caused by a combination of the mechanical properties of the muscle fibres and a refractory state in the MSCs. Consistent with the literature, the current model predicts that the dynamic component is due to a rapid stress increase during the ramp. More novel predictions from the model are the mechanisms to explain the initial peak in the dynamic component. At the onset of the ramp, all MSCs are sensitive to external stimuli, but as they become refractory (inactivated), fewer MSCs are able to respond to the continuous stretch, causing a sharp decrease after the peak response. The same mechanism could contribute a faster component in the ‘sensory habituation’ of mechanoreceptors, in which a receptor responds more strongly to the first stimulus episode during repetitive stimulation

LONG-TERM CHANGES IN CANADA GOOSE NEST SUCCESS AND NEST DENSITIES AT AN IOWA WETLAND COMPLEX

Giant Canada geese (Branta canadensis maxima) were extirpated from Iowa by the early 1900s due to unregulated hunting, egg gathering, and wetland drainage in the nineteenth century (Bishop 1978). Ef- forts to reintroduce Canada geese in Iowa began in 1964 (Bishop and Howing 1972) and involved releasing flightless adults and goslings at nearly 30 sites across the state (Zenner and LaGrange 1998a). In 1972, 13 flightless pairs were released at Rice Lake Wildlife Management Area (WMA; Bishop 1978). By 1989, the breeding population of Canada geese at Rice Lake WMA had increased to 420 nesting adults (G. G. Zenner, Iowa Department of Natural Resources, unpublished data). Canada goose nest success and nest densities were documented from 1989–1991 on extant islands at Rice Lake WMA (Zenner and LaGrange 1998b). Rice Lake WMA (43.379497, –93.472715) is located in north-central Iowa and lies within the southernmost portion of the Prairie Pothole Region. This wetland complex consists of Rice Lake, a 409-ha shallow, natural lake with a maximum depth of 3 m and 20 natural islands ranging in size from 0.04 to 3.9 ha, and Joice Slough, a 73-ha marsh with a maximum depth of 1 m and 15 natural islands ranging in size from 0.02 to 3.19 ha (Zenner and LaGrange 1998b). During 1989–1991, potential Canada goose nest sites included islands, elevated structures, and muskrat houses. Over the course of that study, drought conditions left Joice Slough completely dry and dramatically lowered water levels at Rice Lake, exposing islands to increased predator activity. Despite the drought, nest densities were high (68–158 nests/ha) and nest success ranged from 40–58% (Zenner and LaGrange 1998b)

Incoherent white-light solitons in nonlinear periodic lattices

We predict the existence of lattice solitons made of incoherent white light: lattice solitons made of light originating from an ordinary incandescent light bulb. We find that the intensity structure and spatial power spectra associated with different temporal frequency constituents of incoherent white-light lattice solitons (IWLLSs) arrange themselves in a characteristic fashion, with the intensity structure more localized at higher frequencies, and the spatial power spectrum more localized at lower frequencies; the spatial correlation distance is larger at lower frequency constituents of IWLLSs. This characteristic shape of incoherent white-light lattice solitons reflects the fact that diffraction is stronger for lower temporal frequency constituents, while higher frequencies experience stronger effective nonlinearity and deeper lattice structure

Community Seismic Network: A Dense Array to Sense Earthquake Strong Motion

The Community Seismic Network (CSN) is currently a 500‐element strong‐motion network located in the Los Angeles area of California (see Fig. 1). The sensors in the network are low‐cost microelectromechanical (MEM) accelerometers that are capable of recording on scale up to accelerations of ±2g. The primary product of the network is a set of measurements of ground shaking in the seconds following a major earthquake. An example of this is shown in Figure 2. The shaking information will be contributed to U.S. Geological Survey products such as ShakeMap (Wald et al., 1999) and ShakeCast (Wald et al., 2006), with the goal of providing first responders a proxy for damage that can guide efforts immediately following the event. The basic premise is the strong ground‐motion shaking varies on a subkilometer scale, which will require a dense network to meaningfully measure the shaking. Evidence for this comes from earthquakes recorded by dense oil company surveys in the Los Angeles area (Clayton et al., 2011)

Mechanotransduction channels in proprioceptive sensory nerve terminals: still an open question?

Mechanosensory transduction (MST) in proprioceptors, and other low threshold mechanosensory nerve terminals (LTMT), has been debated intensely for decades. MST in muscle spindles produces a receptor potential that encodes stimulus speed and duration, is predominantly due to Na+, a little Ca2+, plus some transient, non-mechanically-gated K+ ion fluxes. The abundant, multiple Na+-selective DEG/ENaC channel isoforms present in all LTMTs seemed obvious Na+ sources, perhaps supplemented with Ca2+-selective TRPs, and Ca2+-activated K+ channels. However, genetic deletions of even multiple DEG/ENaC genes produces only mild functional perturbation. Conversely, deleting the more recently discovered Piezo2 mechanosensory protein profoundly impairs LTMT responses, including in muscle spindles. Yet, its transient opening, non-Na+-selectivity and pharmacology do not reflect known receptor potential and response properties. A Ca2+-dependent recycling vesicle pool that we have shown is essential for mechanosensitivity, plus other recent DEG/ENaC discoveries, may reconcile these conflicting observations. We propose the abundance of axolemmal MST complexes, comprising untested DEG/ENaC combinations, is controlled by Piezo2-gated Ca2+ influx that regulates their vesicular insertion and retrieval