Engagement of gaze in capturing targets for future sequential manual actions

We investigated the role of saccadic gaze fixations in encoding target locations for planning a future manual task consisting of a sequence of discrete target-oriented actions. We hypothesized that fixations of the individual targets are necessary for accurate encoding of target locations and that there is a transfer of sequence information from visual encoding to manual recall. Subjects viewed four targets presented at random positions on a screen. After various delays following target extinction, the subjects marked the remembered target locations on the screen with the tip of a hand-held stick. When the targets were presented simultaneously among distracting elements, the overall accuracy of marking increased with presentation time and total number of targets fixated because the subjects had to serially fixate the individual targets to locate them. Without distractors, the marking accuracy was similarly high regardless of duration of target presentation (0.25-8 s) and number of targets fixated; it was comparable to that with distractors when all four targets had been fixated. This indicates parallel encoding of target locations largely based on peripheral vision. Location memory was stable in these tasks over the delay periods investigated (0.5-8 s). With parallel encoding there was a "shrinkage" in the visuomotor transformation, i.e., the distances between the markings were systematically smaller than the corresponding inter-target distances. When the targets were presented sequentially without distractors, marking accuracy improved with the total number of targets fixated and shrinkage in the visuomotor transformation occurred only with parallel encoding, i.e., when subjects did not fixate the targets. In all experimental conditions for trials in which targets were fixated during encoding, there was little correspondence between the marking sequence and the sequence in which the targets were fixated. We conclude that subjects benefit from fixating targets for subsequent target-oriented manual actions when the targets are presented among distractors and when presented sequentially; when distinct targets are presented simultaneously against a blank background, they are efficiently encoded in parallel largely by peripheral vision.     

Identification of MEN1 gene mutations in sporadic carcinoid tumors of the lung

Lung carcinoids occur sporadically and rarely in association with multiple endocrine neoplasia type 1 (MEN1). There are no well defined genetic abnormalities known to occur in these tumors. We studied 11 sporadic lung carcinoids for loss of heterozygosity (LOH) at the locus of the MEN1 gene on chromosome 11q13, and for mutations of the MEN1 gene using dideoxy fingerprinting. Additionally, a lung carcinoid from a MEN1 patient was studied. In four of 11 (36%) sporadic tumors, both copies of the MEN1 gene were inactivated. All four tumors showed the presence of a MEN1 gene mutation and loss of the other allele. Observed mutations included a 1 bp insertion, a 1 bp deletion, a 13 bp deletion and a single nucleotide substitution affecting a donor splice site. Each mutation predicts truncation or potentially complete loss of menin. The remaining seven tumors showed neither the presence of a MEN1 gene mutation nor 11q13 LOH. The tumor from the MEN1 patient showed LOH at chromosome 11q13 and a complex germline MEN1 gene mutation. The data implicate the MEN1 gene in the pathogenesis of sporadic lung carcinoids, representing the first defined genetic alteration in these tumors.      

Managing people: the breakfast menu

Discusses an exploratory study of the impact of NHS reforms on the management of staff. Argues that "management" has moved from a view that staff should be provided with a secure and comfortable working environment to "labour" being viewed simply as a factor of production. The result seems to be an unprecedented sense of alienation among significant numbers of NHS staff. Proposes possible ways forward. The first focuses on the "means", accepting that the "ends" of the NHS will, for the foreseeable future, be dominated by the market. The second examines more closely the market-driven, business "end" or purpose and challenges the unitary view of the NHS Trust as a coherent business entity. Beyond these short- to medium-term responses, concludes that a return to a somewhat more flexible and less hard-edged human resources philosophy is a longer-term investment as the labour market tightens and skilled staff become scarcer in the later 1990s.     

Pseudocyesis in an adolescent using the long-acting contraceptive Depo-Provera.

A case report documents a Hispanic adolescent, 17 years of age, with pseudocyesis, who became amenorrheic using Depo-Provera to prevent a second pregnancy. Pseudocyesis includes classic symptoms of pregnancy such as nausea, breast enlargement and pigmentation, abdominal distention, and amenorrhea in nonpregnant women. It demonstrates the to control one's physical aspect at the level of hypothalamus. The involvement that contributed to her pseudocyesis--in this case, of her mother and boyfriend -- was not unusual. The abrupt resolution was brought on by normal menstrual period that began after she voluntarily missed her Depo-Provera injection. However, her ambivalence about a pregnancy became clear after she and her family received counseling. While the agenda had been to help her prevent a pregnancy, hers had not been as clear and uncomplicated. Her subsequent conception was a very positive one for her and her family, which helped to resolve the situation.     

The impact of multifocused interventions on sharps injury rates at an acute-care hospital.

OBJECTIVE: To determine the impact of a multifocused interventional program on sharps injury rates. DESIGN: Sharps injury data were collected prospectively over a 9-year period (1990-1998). Pre- and postinterventional rates were compared after the implementation of sharps injury prevention interventions, which consisted of administrative, work-practice, and engineering controls (ie, the introduction of an anti-needlestick intravenous catheter and a new sharps disposal system). SETTING: Sharps injury data were collected from healthcare workers employed by a mid-sized, acute-care community hospital. RESULTS: Preinterventional annual sharps injury incidence rates decreased significantly from 82 sharps injuries/1,000 worked full-time-equivalent employees (WFTE) to 24 sharps injuries/1,000 WFTE employees postintervention (P<.0001), representing a 70% decline in incidence rate overall. Over the course of the study, the incidence rate for sharps injuries related to intravenous lines declined by 93%, hollow-bore needlesticks decreased by 75%, and non-hollow-bore injuries decreased by 25%. CONCLUSION: The implementation of a multifocused interventional program led to a significant and sustained decrease in the overall rate of sharps injuries in hospital-based healthcare workers.     

General solution for diffusion-controlled dissolution of spherical particles. 1. Theory.

Three classical particle dissolution rate expressions are commonly used to interpret particle dissolution rate phenomena. Our analysis shows that an assumption used in the derivation of the traditional cube-root law may not be accurate under all conditions for diffusion-controlled particle dissolution. Mathematical analysis shows that the three classical particle dissolution rate expressions are approximate solutions to a general diffusion layer model. The cube-root law is most appropriate when particle size is much larger than the diffusion layer thickness, the two-thirds-root expression applies when the particle size is much smaller than the diffusion layer thickness. The square-root expression is intermediate between these two models. A general solution to the diffusion layer model for monodispersed spherical particles dissolution was derived for sink and nonsink conditions. Constant diffusion layer thickness was assumed in the derivation. Simulated dissolution data showed that the ratio between particle size and diffusion layer thickness (a0/h) is an important factor in controlling the shape of particle dissolution profiles. A new semiempirical general particle dissolution equation is also discussed which encompasses the three classical particle dissolution expressions. The success of the general equation in explaining limitations of traditional particle dissolution expressions demonstrates the usefulness of the general diffusion layer model.     

Prospective study design for the Heidelberg retina tomograph: the effect of change in focus setting

Background: Image scaling on the Heidelberg Retina Tomograph (HRT) is based on an axial model of ametropia. In the longitudinal follow-up of patients, refractive changes in ametropia may occur; the HRT interprets such change as being axial in origin. This results in an apparent alteration in the size of fundus features with time and in reduced sensitivity of the instrument to subtle changes relating to disease progression. The aim of this study was to determine the effect of changing HRT focus settings on the absolute scaling of topography images. Methods: Seven image series were acquired of the optic nerve head of a single emmetropic eye at each of a range of panel focus settings under three conditions: (A) emmetropia, (B) trial lens-induced ametropia, (C) contact lens-induced ametropia. A masked observer measured the separation between two defined retinal vascular bifurcations for each topography image. bb Results: The measured distance decreased with a positive shift in focus. There was a significant difference in distance with change in focus setting for all conditions (A P<0.008, B and C P<0.0001). Over equivalent focus ranges, data from the three groups were not significantly different, lying within the 95% confidence limits at each setting. The mean standard deviation for the distance measure was 10 m. Conclusion: Adjustment in focus settings to compensate for refractive change in eyes of stable axial length and keratometry induces a change in the topography measures using the HRT. It is recommended that, for the detection of subtle change over time, refractive changes are corrected without a change in the panel focus setting.