Single amino acid substitutions can further increase the stability of a thermophilic L-lactate dehydrogenase

Lactate dehydrogenases are of considerable interest as stereospecificcatalysts in the chemical preparation of enantiomerically pure-hydroxyacid synthons. For such applications in synthetic organicchemistry it would be desirable to have enzymes which tolerateelevated temperatures for prolonged reaction times, to increaseproductivity and to extend then applicability to poor substrates.Here, two examples are reported of significant thermostabilizations,induced by sitedirected mutagenesis, of an already thermostableprotein, the L-lactate dehydrogenase (EC 1.1.1.27 [EC] , 35 kDa permonomer subunit) from Bacillus stearothermophilus. Thermal inactivationof this enzyme is accompanied by irreversible unfolding of thenative protein structure. The replacement of Argl71 by Tyr stabilizesthe enzyme against thermal inactivation and unfolding. Thisstabilizing effect appears to be based on improved interactionsbetween the subunits in the core of the active dimeric or tetramericforms of the enzyme. The thermal stability of L-lactate dehydrogenasevariants with an active site Arg residue, either in the 171(wild-type) or in the 102 position, is further increased bysulfate ions. The two stabilizing effects are additive, as foundfor the Argl71Tyr/ Gln1O2Arg double mutant, for which the stabilityof the protein in 100 mM sulfate solution reaches that of L-lactatedehydrogenases from extreme thermophiles. All mutant proteinsretain significant catalytic activity, both in the presenceand absence of stnhilfoing salts, and are viable catalysts inpreparative scale reactions.     

Brain-computer interfaces for 1-D and 2-D cursor control: designs using volitional control of the EEG spectrum or steady-state visual evoked potentials.

We have developed and tested two electroencephalogram (EEG)-based brain-computer interfaces (BCI) for users to control a cursor on a computer display. Our system uses an adaptive algorithm, based on kernel partial least squares classification (KPLS), to associate patterns in multichannel EEG frequency spectra with cursor controls. Our first BCI, Target Practice, is a system for one-dimensional device control, in which participants use biofeedback to learn voluntary control of their EEG spectra. Target Practice uses a KPLS classifier to map power spectra of 62-electrode EEG signals to rightward or leftward position of a moving cursor on a computer display. Three subjects learned to control motion of a cursor on a video display in multiple blocks of 60 trials over periods of up to six weeks. The best subject's average skill in correct selection of the cursor direction grew from 58% to 88% after 13 training sessions. Target Practice also implements online control of two artifact sources: 1) removal of ocular artifact by linear subtraction of wavelet-smoothed vertical and horizontal electrooculograms (EOG) signals, 2) control of muscle artifact by inhibition of BCI training during periods of relatively high power in the 40-64 Hz band. The second BCI, Think Pointer, is a system for two-dimensional cursor control. Steady-state visual evoked potentials (SSVEP) are triggered by four flickering checkerboard stimuli located in narrow strips at each edge of the display. The user attends to one of the four beacons to initiate motion in the desired direction. The SSVEP signals are recorded from 12 electrodes located over the occipital region. A KPLS classifier is individually calibrated to map multichannel frequency bands of the SSVEP signals to right-left or up-down motion of a cursor on a computer display. The display stops moving when the user attends to a central fixation point. As for Target Practice, Think Pointer also implements wavelet-based online removal of ocular artifact; however, in Think Pointer muscle artifact is controlled via adaptive normalization of the SSVEP. Training of the classifier requires about 3 min. We have tested our system in real-time operation in three human subjects. Across subjects and sessions, control accuracy ranged from 80% to 100% correct with lags of 1-5 s for movement initiation and turning. We have also developed a realistic demonstration of our system for control of a moving map display (http://ti.arc.nasa.gov/).     

Can male decorticate rats copulate?

28 hooded sexually experienced or naive male rats, subjected to neocortex removal or neocortex plus hippocampus removal, were paired with female rats for up to 180 days and compared with 14 control rats with respect to success and latency to impregnate the female. All of the controls and half of the brain-damaged Ss successfully impregnated females at least once. Success was not correlated with lesion type or presurgical experience. The brain-damaged Ss took longer to impregnate the females than did controls. Since the ablations were extensive, more than 95% of the neocortex in many Ss, results show that decorticate rats can copulate. Presumably the intact subcortical structures are sufficient for male copulation, but cortical structures in some way facilitate rapid female impregnation. (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Some ethical concerns regarding the individual psychotherapy of the married client.

A brief review of the literature establishes the high potential for disturbance of a client's marital relationship following individual psychotherapy. Several problems possibly inherent in the conduct of therapy with only one member of a marital dyad are discussed, as well as some of their probable sources. The importance of informed consent to treatment is stressed with regard to ensuring that potential clients are aware of the possible negative effects of therapy on their marital relationship. The systemic view of the spouse as necessarily involved in the maintenance and modification of the client's complaints, provides an alternative to individual psychotherapy: The spouse must be a part of their therapy from the beginning. It is suggested that the ethical responsibility of the therapist is toward the greatest overall benefit for the client and should concern the interpersonal as well as the psychological environments of the clients they serve. (French abstract) (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Learning disabled boys' performance and self-assessments on physical fitness tests

30 learning disabled boys drawn from a segregated private school for learning disabled children and 22 from a public school mainstream program and 22 nondisabled boys performed two physical fitness tests, sit-ups and shuttle run in one of two conditions. While normal achievers performed significantly better on one of the tests, there were no differences between the two samples of learning disabled youngsters. However, students' comparisons of their performance with classmates' indicated that learning disabled youngsters in the private school ranked themselves more favorably than those in mainstream classrooms.     

Evaluation of integrated software development environments: Challenges and results from three empirical studies

Evidence shows that integrated development environments (IDEs) are too often functionality-oriented and difficult to use, learn, and master. This article describes challenges in the design of usable IDEs and in the evaluation of the usability of such tools. It also presents the results of three different empirical studies of IDE usability. Different methods are sequentially applied across the empirical studies in order to identify increasingly specific kinds of usability problems that developers face in their use of IDEs. The results of these studies suggest several problems in IDE user interfaces with the representation of functionalities and artifacts, such as reusable program components. We conclude by making recommendations for the design of IDE user interfaces with better affordances, which may ameliorate some of most serious usability problems and help to create more human-centric software development environments.     

Clustering semantically heterogeneous distributed aggregate databases

Databases developed independently in a common open distributed environment may be heterogeneous with respect to both data schema and the embedded semantics. Managing schema and semantic heterogeneities brings considerable challenges to learning from distributed data and to support applications involving cooperation between different organisations. In this paper, we are concerned mainly with heterogeneous databases that hold aggregates on a set of attributes, which are often the result of materialised views of native large-scale distributed databases. A model-based clustering algorithm is proposed to construct a mixture model where each component corresponds to a cluster which is used to capture the contextual heterogeneity among databases from different populations. Schema heterogeneity, which can be recast as incomplete information, is handled within the clustering process using Expectation-Maximisation estimation and integration is carried out within a clustering iteration. Our proposed algorithm resolves the schema heterogeneity as part of the clustering process, thus avoiding transformation of the data into a unified schema. Results of algorithm evaluation on classification, scalability and reliability, using both real and synthetic data, demonstrate that our algorithm can achieve good performance by incorporating all of the information from available heterogeneous data. Our clustering approach has great potential for scalable knowledge discovery from semantically heterogeneous databases and for applications in an open distributed environment, such as the Semantic Web.     

Truck sizing models for recyclables pick-up

Growing public concerns about the environmental consequences of waste disposal have led to an increase in recycling efforts. In many communities, curbside collection programs have been instituted for collecting recyclables from households for transfer to material recovery facilities. In most programs the cost of collection is the dominant cost. Despite the high cost and environmental importance of collecting recyclables from households, most municipal collection systems are designed and operated without a clear understanding of what factors drive those costs and how they might be reduced. In this paper, models for determining truck configurations, as well as optimal compartment sizes for recyclables collection are developed. Constraints arising from the operation of the trucks are formulated, and solution schemes are presented. In addition, a procedure for optimally partitioning a vehicle used to collect source-separated material is discussed. Several scenario based planning approaches are developed. Use of the truck sizing models as an industry decision tool and the associated benefits of applying the truck sizing models and the solution methodology to a contract based collection program are also discussed.