Reactivity studies of 2,3,5,6-Tetra(2-pyridyl) pyrazine (tppz) with first-row transition metal ions

Reactions of 2,3,5,6-tetra(2-pyridyl) pyrazine (tppz) with [ML₆][X]₂ (L = CH₃CN, H₂O;X = [BF₄]⁻, [ClO₄]⁻, [NO₃]⁻ [BArF]⁻(BArF - B[3,5-C₆H₃(CF₃)₂]₄) lead to the high-yield formation of mononuclear [M(tppz)₂]²⁺, (M = Mn^II, Fe^II, Co^II, and Ni^II) and dinuclear [Ni₂(tppz)(CH₃CN)₆]⁴⁺ species. The new compounds were fully characterized by X-ray crystallographic, spectroscopic, and magnetic susceptibility measurements. Surprisingly, the 2:1 M:tppz reactions did not lead to isolation of the dinuclear species except in the case of Ni(II). It was further noted that even in the case of the Ni reactions, the nuclearity of the product depends on the choice of anions and the reaction conditions. Magnetic measurements of the mononuclear species [Co(tppz)₂]²⁺ revealed thermally induced spin-crossover behavior from a high-spin S = 3/2 at higher temperatures to a low-spin S = 1/2 complex at lower temperatures. The dinuclear compound [Ni₂(tppz)(CH₃CN)₆]⁴⁺ exhibits a weak anti-ferromagnetic interaction through the bridging tppz ligand.     

Alcohol Consumption Moderates the Link Between Cannabis Use and Cannabis Dependence in an Internet Survey.

The link between cannabis use and cannabis dependence remains poorly understood. Some people use cannabis regularly without signs of dependence; others show dependence despite using less. This study examined alcohol consumption as a moderator of this association. A sample of 476 people (primarily Caucasian men) who used cannabis at least once per week reported their alcohol consumption, cannabis use, and cannabis dependence symptoms in an Internet survey. Regressions revealed significant interactions between measures of cannabis use and alcohol consumption when predicting cannabis dependence. Cannabis use covaried with cannabis dependence, particularly in people who consumed alcohol frequently or in large amounts per week. Despite limitations, these data suggest that alcohol may decrease the safety of cannabis consumption. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Michael J. Mahoney (1946-2006).

Presents an obituary for Micheal J. Mahoney. Mahoney made immeasurable contributions to the field of psychology as an influential researcher, a prolific writer, and an innovative pioneer in bringing constructivist philosophy into psychotherapy. A deep thinker, a revolutionary-spirited theorist, and a passionate philosopher, Michael challenged the dominant paradigms of behavioral and cognitive psychology, inspiring psychologists to consider ever more complex models of human experience, to think in a more interdisciplinary way, and to relate more compassionately to the inevitable human experiences of suffering and change. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Nursing, healing and spirituality

The premise of this article is that nurses are healers, primarily through the caring relationships they form with patients. Caring calls out an individual's inner strengths. These strengths include spiritual resources which support integration or wholeness of body, mind and spirit. Many nurses are unsure about giving spiritual care. This author encourages nurses to reflect on their own spirituality and learn spiritual care skills. By addressing the spiritual dimension in patient care, nurses can truly be holistic practitioners and positively affect the mental and physical health of their patients.     

Time-varying analysis-synthesis systems based on filter banks andpost filtering

Perfect reconstruction (PR) time-varying analysis-synthesis filter banks are those in which the filters are allowed to change from one set of PR filter banks to another as the input signal is being processed. Such systems have the property that, in the absence of coding, they faithfully reconstruct every sample of the input. Various methods have been reported for the time-varying filter bank design; all of them, however, utilize structures for conventional PR filter banks. These conventional structures that have been applied in the past result in different limitations in each method. This paper introduces a new structure for exactly reconstructing time-varying analysis-synthesis filter banks. This structure consists of the conventional filter bank followed by a time-varying post filter. The new method requires neither the redesign of the analysis sections nor the use of any intermediate analysis filters during transition periods. It provides a simple and elegant procedure for designing time-varying filter banks without the disadvantages of the previous methods     

DSP for practicing engineers: a case study in Internet course delivery

With the explosion of the Internet and the desire of many institutions to disseminate courses across the world, many students look to online education with promise. However, institutions planning to provide distance learning opportunities may wish to have a model to analyze before venturing forth. There are many factors that ultimately influence the methods of delivery, content, length, and technical support for an online course. This paper presents the design, implementation, and evaluation of an online course titled DSP for Practicing Engineers at the Georgia Institute of Technology, Atlanta, and analyzes feedback from students who have taken the course and the staff who administered it. Different aspects of course development are discussed at length, including curriculum and media type.     

Rotational vertebral artery occlusion: a mechanism of vertebrobasilar insufficiency

OBJECTIVE: Symptomatic dynamic changes in blood flow secondary to vertebral artery compression with rotational head motion are evaluated in a series of patients as a cause for posterior circulation transient ischemic attacks. These cases are classic examples of rotational vertebral artery occlusion and allow for the discussion of the anatomic basis, angiographic features, and treatment options. ILLUSTRATIVE CASES: In our series, symptoms of vertebrobasilar insufficiency were reproducible with rotational head movement. Compression of the vertebral artery was demonstrated angiographically. The correct site of occlusion of the vertebral artery was apparent only by dynamic angiography with progressive head rotation. All of the patients presented in the illustrative cases had occlusion at the C2 level; however, one patient had been previously misdiagnosed and another had an additional site of occlusion. The anatomic course of the vertebral artery is described in addition to the sites of rotational occlusion. CONCLUSION: Rotational vertebral occlusion is an important cause of vertebrobasilar symptoms, which may lead to permanent neurological deficit if left undiagnosed. Dynamic angiography is the established method of diagnosis. Great care must be taken to avoid misdiagnosing the site of occlusion or missing a second occlusive site. For this reason, it is crucial to have a thorough understanding of the anatomic course of the vertebral artery and the muscular and tendinous insertions, which may cause rotational occlusion. The decision for treatment must be based on the site of occlusion as well as the assessment of the patient as a surgical candidate. A review of the literature reveals that surgical treatment is effective and must be considered to avoid further morbidity.     

Time-varying filter banks and wavelets

Time-varying filter banks and wavelets are studied and a design procedure is presented. In the resulting analysis-synthesis structures, the analysis filters and the corresponding synthesis filters, the number of bands, and the decimation rates can be changed with time. Such structures can be considered as time-frequency overlapping block transforms. From this viewpoint, the tiling of the time-frequency plane and the corresponding basis functions are changed in time. The time-varying discrete wavelet transforms can be considered a special case of time-varying overlapping block transforms and are studied in detail. The formulation is based on the time domain formulation of time-varying analysis-synthesis structures. The design procedure can be used to design time-varying perfectly invertible transformations with a finite number of distinct analysis structures. For adaptive filter bank application, a least squares design method is also studied     

Approximate Model Spaces for Model-Robust Experiment Design

Optimal designs depend upon a prespecified model form. A popular and effective model-robust alternative is to design with respect to a set of models instead of just one. However, model spaces associated with experiments of interest are often prohibitively large and so algorithmically generated designs are infeasible. Here, we present a simple method that largely eliminates this problem by choosing a small set of models that approximates the full set and finding designs that are explicitly robust for this small set. We build our procedure on a restricted columnwise-pairwise algorithm, and explore its effectiveness for two model spaces in the literature. For smaller full model spaces, we find that the designs constructed with the new method compare favorably with robust designs that use the full model space, with construction times reduced by orders of magnitude. We also construct designs that heretofore have been unobtainable due to the size of their model spaces. Supplementary material (available online) includes code, designs, and additional results.