Isidd: An interactive system for inductive database design

When designing a deductive database, the designer has to decide for each predicate (or relation) whether it should be defined extensionally or intensionally and what the definition should look like. An intelligent interactive system is presented to assist the designer in this task. It starts from an example state ofa database in which all predicates are defined extensionally. It can then compact the database by transforming extensionally defined predicates into intensionally defined ones. These predicates can be chosen by the user or by the system itself. Further compaction is possible by inventing new predicates; this invention is controlled by user-specified templates. The systemalso proposes semantic integrity constraints to the user. These do not lead to extra compaction but can be used to make the database more robust. The intelligent system employs techniques from the area of inductive logic programming.     

Three-dimensional organization of otolith-ocular reflexes in rhesus monkeys. III. Responses To translation

The three-dimensional (3-D) properties of the translational vestibulo-ocular reflexes (translational VORs) during lateral and fore-aft oscillations in complete darkness were studied in rhesus monkeys at frequencies between 0.16 and 25 Hz. In addition, constant velocity off-vertical axis rotations extended the frequency range to 0.02 Hz. During lateral motion, horizontal responses were in phase with linear velocity in the frequency range of 2-10 Hz. At both lower and higher frequencies, phase lags were introduced. Torsional response phase changed more than 180 degrees in the tested frequency range such that torsional eye movements, which could be regarded as compensatory to "an apparent roll tilt" at the lowest frequencies, became anticompensatory at all frequencies above approximately 1 Hz. These results suggest two functionally different frequency bandwidths for the translational VORs. In the low-frequency spectrum (<0.5 Hz), horizontal responses compensatory to translation are small and high-pass-filtered whereas torsional response sensitivity is relatively frequency independent. At higher frequencies however, both horizontal and torsional response sensitivity and phase exhibit a similar frequency dependence, suggesting a common role during head translation. During up-down motion, vertical responses were in phase with translational velocity at 3-5 Hz but phase leads progressively increased for lower frequencies (>90 degrees at frequencies <0.2 Hz). No consistent dependence on static head orientation was observed for the vertical response components during up-down motion and the horizontal and torsional response components during lateral translation. The frequency response characteristics of the translational VORs were fitted by "periphery/brain stem" functions that related the linear acceleration input, transduced by primary otolith afferents, to the velocity signals providing the input to the velocity-to-position neural integrator and the oculomotor plant. The lowest-order, best-fit periphery/brain stem model that approximated the frequency dependence of the data consisted of a second order transfer function with two alternating poles (at 0.4 and 7.2 Hz) and zeros (at 0.035 and 3.4 Hz). In addition to clearly differentiator dynamics at low frequencies (less than approximately 0.5 Hz), there was no frequency bandwidth where the periphery/brain stem function could be approximated by an integrator, as previously suggested. In this scheme, the oculomotor plant dynamics are assumed to perform the necessary high-frequency integration as required by the reflex. The detailed frequency dependence of the data could only be precisely described by higher order functions with nonminimum phase characteristics that preclude simple filtering of afferent inputs and might be suggestive of distributed spatiotemporal processing of otolith signals in the translational VORs.     

Dosimetric verification of the dynamic intensity-modulated radiation therapy of 92 patients

The initial period in the establishment of syringe exchange projects is often characterized by overt conflict: between community AIDS activists, on the one hand, and public officials and political leaders who remain ideologically opposed to the introduction of measures perceived as condoning illicit drug use. In this context, professionals concerned with legitimating the new institutions of syringe exchange may sometimes neglect aspects of their everyday logistics and social organization, obscuring the important choices which have to be made to carry these initiatives forward. In particular, the contrast between formally-constituted institutions-the "storefront" or "community-based" syringe exchange programs (SEPs)-and the model of low-threshold syringe availability through pharmacies, vending machines, and user networks, is here presented not as an either/or choice but rather as a pair of complementary strategies which respond to diverse needs and target different populations. The advantages and disadvantages of each particular approach make it likely that maximum effectiveness will be achieved through a combination of every possible form of needle distribution, each tailored to specific and cultural circumstances. The case is here examined in the light of the experience of the SEPs in New York City, from their clandestine origins in 1990 through their first years of official functioning in 1992-1996.     

Spontaneous priming of a downstream module in 6-deoxyerythronolide B synthase leads to polyketide biosynthesis

Modular polyketide synthases such as 6-deoxyerythronolide B synthase (DEBS) catalyze the biosynthesis of structurally complex natural products by repetitive condensation of simple carboxylic acid monomers. The synthase can be divided into groups of domains, called "modules", each of which is responsible for one cycle of chain extension and processing. The modular nature of these enzymes suggests that the biosynthetic pathway might be rationally reprogrammed by manipulation of synthases at the domain level. Although, several examples of successful engineering of DEBS have been reported, a critical issue which has not been well-studied is the tolerance of "downstream" active sites to nonnatural substrates. Here, we report that the terminal modules of DEBS, which normally process highly functionalized intermediates, are competent to carry out their natural functions on smaller, more simple substrates. Expressed in the absence of other DEBS proteins, the DEBS3 protein, which normally carries out the final two extension cycles in the synthesis of 6-deoxyerythronolide B (6-dEB), is spontaneously primed with a C3 carboxylic acid. This substrate is then extended through two condensation cycles to form a triketide. Tolerance of the "shortened" intermediates in the biosynthesis of this triketide, in combination with results reported elsewhere [Jacobsen, J. R., Hutchinson, C. R., Cane, D. E., and Khosla, C. (1997) Science 277, 367-369], suggests that relaxed substrate specificity may be a common feature of modular polyketide synthases. Interestingly, priming of DEBS3 appears to proceed, not by acyltransfer from propionyl-CoA, but by decarboxylation of an enzyme-bound methylmalonyl extender unit. This is the second example of decarboxylative priming within DEBS [see also Pieper, R., Gokhale, R. S., Luo, G., Cane, D. E., and Khosla, C. (1997) Biochemistry 36, 1846-1851] and suggests that, in the absence of an acceptable primer (or transferred intermediate), decarboxylative priming of ketosynthase domains may be a general property of modular polyketide synthases.     

Nature of life events and difficulties in depressed adolescents

OBJECTIVE: To examine the significance of acute life events and ongoing difficulties in adolescents with a recent major depressive disorder. METHOD: Adolescents (aged 13-18 years) with a recent episode of major depressive disorder based on DSM-III-R (n = 26) and normal controls free of any Axis I lifetime psychiatric disorder (n = 15) were assessed using the investigator-based Life Events and Difficulties Schedule (LEDS). RESULTS: Traditionally defined severe events were more likely to occur in the year prior to onset among depressed adolescents (46%) than in a comparable period among normal controls (20%), but these differences did not reach statistical significance. Expanding the definition of severe events to include those events focused on others important to the adolescent resulted in a significantly higher percentage of depressed adolescents having one or more refined "severe" events in the year prior to onset (62%) compared with normal controls (27%) (p < or = .02). It is interesting that one half of the depressed adolescents had two or more refined severe events occur during the year prior to onset compared with none of the normal controls (p < or = .01). Further analyses showed that depressed adolescents were significantly more likely to have a major difficulty precede the onset of their depression (27%) compared with normal controls (0%) (p < or = .04). CONCLUSIONS: The results suggest that depressed adolescents are exposed to high levels of stress prior to becoming depressed. Future investigations might benefit from using the LEDS with adolescents to assess acute and ongoing stressors.     

Measuring impact of nursing intervention on cancer patients' ability to control symptoms

Cancer patients' ability to control symptoms and to maintain reasonable quality of life is limited due to lack of knowledge, guidance, and instructions from health care providers, who usually refrain from transferring responsibility for the treatment to the patient. The present study describes a measured effect of a structured nursing intervention in which nurses were trained to apply the self-care model to 48 ambulatory cancer patients under chemo- or radiotherapy or both. The intervention included 10 structured home visits to each patient during 3 months, in which the nurse assessed symptoms and advised, guided, supported, and educated the patient in the relevant areas. The symptoms were quantitatively assessed using the Symptom Control Assessment (SCA) instrument, which was developed and validated specifically for this study. The SCA relates to 16 signs, symptoms, and complaints that encompass both the universal and the deviation-from-health needs, in addition to anxiety, body image, and sexuality. The instrument allows either the patient or the nurse to rate the severity of the complaint, the patient's independence in controlling it, the patient's perception of the familial and external help extended to him or her, and the knowledge of the symptom and its control possessed by the patient. Also, the SCA allows comparing the patient's ratings with the professional view of the visiting nurse. The SCA was proven to be a highly reliable and valid instrument. The results indicate that the intensity of the complaints decreased in the experimental group during the 3-month period while they increased in the matched control group, creating a considerable difference between the two groups on multivariate analysis of covariance (MANCOVA). On t-tests, significant improvement was found in 15 out of the 16 symptoms, including pain. The greatest reduction was found in the "psychosocial symptoms," namely anxiety, sociability, body image, and sexuality. Similarly, the patients' independence, knowledge, and perception of familial help increased in the experimental group and declined in the control group. Perhaps the most meaningful change was a significant increase in the ability of the experimental patients to assume responsibility for their own treatment as it is reflected by the increase of the independence ratings for all 16 symptoms. This is in sharp contrast to the decrease in 15 of the 16 symptoms among control patients. The results suggest that the self-care approach is effective also in improving the quality of life for unstable cancer patients by reduction of suffering and increase in controlling capabilities.     

冶金企业实验室认可工作探讨

对冶金企业实验室认可方面的工作进行了几方面的探讨冶金企业实验室的基本状况;冶金企业实验室认可的目的;冶金企业实验室认可的基本状况以及认可的检测实验室(tesing laboratory)应注意的几个问题.     

Validation of procedures for fatigue life assessment of a steel pressure vessel

A full‐size pressure vessel, made of steel plate P355NL1 (EN 10028‐3), was tested under repeated internal pressure until its failure was observed. Also, four representative structural details of the tested pressure vessel were fatigue tested under load control with a stress ratio of R= 0. These structural details are basically two seam‐welded joints, namely a butt‐welded joint and a joggle‐welded joint, one plate attachment using fillet‐welded joints and a nozzle‐to‐plate connection. S–N curves were generated for these details based on both nominal and structural stresses. These curves are critically compared with those proposed in pressure vessel design codes like the ASME VIII – Division 2, the PD 5500 and the recently approved EN procedures, the EN 13445 standard. Finally, predictions of the fatigue life of the pressure vessel, obtained using the previously referred procedures and the experimentally derived design curves are critically compared with the observed life of the vessel.     

Optimality in discrete model-following systems in the presence of unmodelled dynamics.

The problem of optimal model-following linear control of discrete stochastic adaptive systems is studied in the presence of unmodelled dynamics. The controller complexity is restricted to that corresponding to the perfectly modelled situation. The key for a control design to be robust in the presence of unmodelled dynamics is closely related to some parametrical conditions that ensure a certain linear filter (involving parametrical uncertainties related to unmodelled dynamics) maintains the output stationarity of any stationary random input signal, as in the nominal situation. Partial results concerning robustness are obtained from stability considerations. In any case, a priori knowledge on the unmodelled dynamics is not available for the implementation of the control law.