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PubMed1996

Decentration of photorefractive keratectomy ablation zones after excimer laser surgery for myopia.

PURPOSE: To devise a method for measuring excimer laser photorefractive keratectomy (PRK) ablation zone decentration. SETTING: Excimer Laser Clinic, Sunderland Eye Infirmary, Sunderland Tyne and Wear, England. METHODS: Fifty-three eyes of 53 consecutive patients having PRK for a spherical myopic refractive error were studied. Preoperative and postoperative corneal topographic maps and differential subtraction maps were produced for each cornea. Using these maps, the distance between ablation zone centers and pupil centers was measured. All measurements were repeated by a second observer. RESULTS: Mean ablation zone decentration was 0.46 mm from the pupil center; 69% of cases decentered 0.50 mm or less. The difference between the two independent measurements was 0.05 +/- 0.06 mm (mean +/- SD). A trend toward superonasal displacement was noted. CONCLUSION: This simple method of measuring zone decentration can be used to compare the refractive results of PRK with those of other procedures.

Cornea↗
PubMed1994

Decentration of the posterior chamber lens implant: a comparison of capsulorhexis with endocapsular surgery.

The optical effect of posterior chamber lens decentration is a well-recognised complication of cataract surgery causing significant symptoms even with the larger-diameter implant optics available. In this paper we present the results of a study of implant decentration occurring with extracapsular surgery, in which we compared a group of patients with one tear in the anterior capsule with a second group with two tears in the anterior capsule. Our findings show that lens decentration is greater in those patients with two tears of the anterior capsule, and this difference is statistically significant.

Aged↗
PubMedDate not supplied

Challenges to achieving value in drug spending in a decentralized country: the Spanish case.

OBJECTIVES: This article presents an overview of the Spanish health sector variables and drug policies as well as highlights the perspectives of new reforms. METHODS: Initially, the text frames the health sector in the sociodemographic context; it describes the past two decades of demographic changes noting particularly the very low birth rate and the growth in the proportion of the elderly. It also summarizes the main aggregate economic trends emphasizing the gross national product growth of near an annual 4% for the past 10 years and the decrease in the unemployment rate from high values of approximately 20% to half that rate in the same period, together with a stabilization of the inflation rate around 4%, still higher than EU average values. Second, this article describes the Spanish health sector organization and financing, underlining that it is mostly a publicly funded system (approximately 80% of total health-care expenditures are public) and that the universal coverage is financed out of general taxation after two decades of transition from social security-based premiums. Simultaneously to that universalization of the health-care rights, Spain started a political decentralization process in almost all the spheres of the public administration, health issues included. The article describes the changes in budgeting, management, and funding that nowadays fully belong to the regions. RESULTS: An essential part of the text is devoted to the pharmaceutical sector and its policies. Drug budgets represent almost 25% of the total public health expenditures; this proportion is approximately 50% of primary care expenditures. The incentive payments to achieve a more efficient prescription are approximately 2% of primary care physicians' gross salary. Doctors in hospitals have scarce incentives related to this issue. Some examples are presented of how this decentralization process affects the pharmaceutical policies that are designed and implemented by both the central and the regional governments. Regions are currently developing health technology assessment departments that will also perform activities on the economic evaluation of drugs. CONCLUSIONS: The planned reforms will still retain at the central government level the control of three major drug policies: authorization, pricing, and reimbursement. Several policies are currently focused on increasing the 6% share of generic drugs in the total drug market toward the EU average. The decentralization will allow the regions to modify some reimbursement policies and mainly to establish new incentives on prescription and purchasing procedures of drugs by the hospitals. The new drug agency is foreseen to assume the utilization of cost-effectiveness studies to provide economic information in the pricing and reimbursement processes.

Budgets↗
PubMed2004

Assessing the performance of primary health centres under decentralized government in Kerala, India.

CONTEXT: Kerala's government health-care system functions relatively well compared with other Indian States, but utilization levels are decreasing due to lack of essential facilities. The opportunity cost of seeking medical care from the government sector is high, even for the poor, with 60-70% of the poor seeking care from the private sector and spending disproportionately on health care (about 40% of income compared with 2.4% by the rich). In 1996, the Kerala government brought primary health centres (PHCs) under the control of local governments (panchayats). OBJECTIVE: To provide an approach to assess PHC performance under decentralized government. METHODS: The study was conducted in three stages. The first stage included all 990 village panchayats in Kerala. The second stage covered 10 panchayats (their respective 10 PHCs and 65 sub-centres) occupying the top five and bottom five ranks in terms of resource allocation to health. Two panchayats (their respective PHCs and sub-centres), one each from the top five and the bottom five, were chosen for the third stage. Published and unpublished government data, panchayat development reports, panchayat and PHC records, facility checklist, and key informant and client exit interviews were used for data collection. FINDINGS: Panchayats in Kerala allocated a lower proportion of resources to health than that allocated by the state government prior to decentralization; while panchayat resources grew at an annual rate of 30.7%, health resources grew at 7.9%. PHCs were funded to the extent of 0.7-2.7% of the total cost. An additional 2% in PHC resources was associated with improved patient load (63.5%), cost-effectiveness (50.8%), medicine supply (49.4%), information (32.8%) and patient satisfaction (12.7%). An annual increase of US$940 in PHC resources would help to extend primary care facilities to 3000 (15.5%) more users. CONCLUSION: Decentralization brought no significant change to the health sector. Active panchayat support to PHCs existed in only a few places, but wherever it was present, the result was positive. Kerala should find an alternative strategy to channel panchayats towards health before health loses its battle for resources.

Efficiency, Organizational↗
PubMed2005

Prevention and promotion in decentralized rural health systems: a comparative study from northeast Brazil.

Policies to reform health care provision often combine the organizational restructuring of decentralization with ideological restructuring through a new model of health care that gives greater weight to prevention and promotion. Decentralization provides a discretionary space to the local health system to define and develop its own activities. The central policy aim to shift the model of health care therefore must rely on incentives rather than directives and is likely to result in variation at local levels in the extent and mode of its implementation. The local processes affecting variation in local implementation of policies for prevention and promotion have not been studied in a developing country. This study does so by comparing two rural health systems with different levels of prevention and promotion activities in one of the poorest regions of Brazil, Ceará State in the northeast. The health system with greater activities of prevention and promotion also has a more advanced stage of decentralization, but this is in combination with many other, interacting influences that differentiate the two health systems' ability to adopt and implement new approaches. While beyond the scope of this paper to detail options for regional and national managers to encourage the adoption of a greater focus on prevention and promotion, it is clear that strategies needs to target not only the vision and actions of local health system staff, but critically also the expectations of the local population and the attitudes of local government.

Brazil↗
PubMed2005

HMIS and decision-making in Zambia: re-thinking information solutions for district health management in decentralized health systems.

At the onset of health system decentralization as a primary health care strategy, which constituted a key feature of health sector reforms across the developing world, efficient and effective health management information systems (HMIS) were widely acknowledged and adopted as a critical element of district health management strengthening programmes. The focal concern was about the performance and long-term sustainability of decentralized district health systems. The underlying logic was that effective and efficient HMIS would provide district health managers with the information required to make effective strategic decisions that are the vehicle for district performance and sustainability in these decentralized health systems. However, this argument is rooted in normative management and decision theory without significant unequivocal empirical corroboration. Indeed, extensive empirical evidence continues to indicate that managers' decision-making behaviour and the existence of other forms of information outside the HMIS, within the organizational environment, suggest a far more tenuous relationship between the presence of organizational management information systems (such as HMIS) and effective strategic decision-making. This qualitative comparative case-study conducted in two districts of Zambia focused on investigating the presence and behaviour of five formally identified, different information forms, including that from HMIS, in the strategic decision-making process. The aim was to determine the validity of current arguments for HMIS, and establish implications for current HMIS policies. Evidence from the eight strategic decision-making processes traced in the study confirmed the existence of different forms of information in the organizational environment, including that provided by the conventional HMIS. These information forms attach themselves to various organizational management processes and key aspects of organizational routine. The study results point to the need for a radical re-think of district health management information solutions in ways that account for the existence of other information forms outside the formal HMIS in the district health system.

Decision Making↗
PubMed1983

Effect of parasympathetic decentralization and paracervical ganglion excision on reproductive function in the rat.

The uterine paracervical ganglion (Frankenhauser's ganglion) contains the terminal ganglion cells of the sacral parasympathetic system and, in some species, the short adrenergic system. Histochemical studies also show numerous chromaffin cells with morphologic attributes of interneurons. The present study explores the function of cell types present in this ganglion, by seeking changes in reproductive function following either parasympathetic decentralization (transection of the cauda equina) or excision of the ganglion itself. Two well-known reproductive phenomena were observed after each surgical intervention, namely, induction of uterine hyperemia by estrogen administration, and maintenance of normal vaginal cycles. Estrogen-induced uterine hyperemia was not affected by parasympathetic decentralization or ganglion excision. Therefore, nerves originating in, or passing through this structure may be eliminated as components of the vascular control mechanism. In contrast, compared to sham-operated controls, ganglionectomy caused a significant reduction in the proportion of animals exhibiting normal vaginal cycles postoperatively (P less than 0.05). Cycle distribution was more evident in animals ganglionectomized on metestrus (P less than 0.01) and proestrus (P less than 0.05) than in animals ganglionectomized on diestrus or estrus. Since parasympathetic decentralization did not produce cycle disruption similar to ganglionectomy, one may conclude that the cycle-modulating effect does not involve preganglionic fibers of the sacral parasympathetic nerves.

Animals↗
PubMed1984

The effect of decentralized education versus increased supply on practice location. Experience with physician assistants and nurse practitioners in California, 1972-1982.

To improve the geographic distribution of physician assistants and nurse practitioners in California, the Primary Care Associate Program established five community-based training sites in outlying areas while continuing to operate its core program within the San Francisco Bay Area. To evaluate this effort, the authors prospectively compared the employment locations of graduates from both groups, achieving a follow-up rate of 95%. Graduates from community sites were twice as likely to locate first practices outside the Bay Area (91% vs. 43%, P less than 0.05) and in towns with less than 10,000 inhabitants (33% vs. 16%, P less than 0.05). Over the decade, the percentage of graduates practicing outside the Bay Area rose from 0 to 9% for trainees both recruited from and entirely trained within the Bay Area versus 76-84 percent for trainees experiencing any element of decentralization. The slopes of these two lines represent the effect of the increasing supply of graduates on practice location away from Stanford (9%); the distance between the lines, the greater effect of decentralization (73%). Given the goal of statewide deployment of a small number of graduates, decentralization appears to have been an effective approach.

Adult↗
PubMed1987

Biochemical and functional evidence for nerve sprouting in the decentralized, hypertrophied rat urinary bladder.

The preganglionic nerves of the rat urinary bladder were cut. The decentralized bladders gained markedly in weight. Both one and four weeks post-operatively, transmural nerve stimulation evoked contractile responses of the muscle strips of the decentralized bladders, that were of the same magnitude as those of the control bladders. However, four weeks post-operatively, the atropine resistant fraction of the response was decreased; consequently, the atropine sensitive (cholinergic) fraction was increased. The activity of the acetylcholine synthesizing enzyme, choline acetyltransferase, was increased at the late time of observation. The present biochemical and functional findings may suggest outgrowth of branches from the decentralized post-ganglionic cholinergic nerves.

Animals↗
PubMed1994

Geographic benefit from decentralized medical education: student and preceptor practice patterns.

The performance of area health education center (AHEC)-stimulated programs and decentralized education for medicine is not well understood. The Statewide Education Activities for Rural Colorado's Health (SEARCH)/AHEC project at the University of Colorado School of Medicine was examined to determine if the program had an effect on the practice location of its graduates. Practice location and specialty of graduates of the University of Colorado School of Medicine (UCSOM) classes 1980-1985 were compared for students who had participated in decentralized SEARCH/AHEC experiences versus students who had not. The majority of the graduates were practicing out of state in 1990. Non-Colorado doctors were more often practicing in rural (non-metropolitan statistical area [MSA]) counties and in towns of fewer than 2,500, 5,000 and 10,000 residents, respectively. In addition, of the 251 active patient care physicians practicing in Colorado communities of fewer than 10,000 in non-MSA counties in 1986, those who precepted UCSOM students on SEARCH rotations were more likely to have remained in their same practice location in 1992 (77.8% versus 62.1% for those who had not precepted students). This analysis of both student and preceptor practice patterns documents the value of decentralized medical education in addressing the geographic and specialty maldistribution of physicians. These results have important policy implications for funding medical education programs.

Area Health Education Centers↗
PubMed1980

Sensitization of the rat parotid gland to secretagogues following either parasympathetic denervation or sympathetic denervation or decentralization.

The sensitivity of the rat parotid gland to chemical agents was examined 2--3 weeks after either parasympathetic denervation or sympathetic denervation or decentralization. The parasympathetically denervated gland was markedly sensitized towards methacholine; a nonspecific supersensitivity mainly mediated via alpha-adrenoceptors was also demonstrated. The sympathetically denervated gland had developed a supersensitivity which was both of the pre- and the postjunctional type; it was predominantly of the former type to noradrenaline and adrenaline, and entirely so to phenylephrine; it was of the latter type to isoprenaline, and also to methacholine. The sympathetically decentralized gland was mainly sensitized towards noradrenaline, adrenaline and isoprenaline. The postjunctional supersensitivity developed towards the sympathomimetic drugs after sympathetic decentralization was of about the same magnitude as that observed after sympathetic denervation; this type of supersensitivity was mainly mediated via beta-adrenoceptors.

Animals↗
PubMed1982

Supersensitivity to substance P and physalaemin in rat salivary glands after denervation or decentralization.

Substance P, a putative neurotransmitter in mammals, and physalaemin, present in the skin of an amphibian, are both undecapeptides and belong to the family of tachykinins. The secretory effect of these tachykinins on parotid and submaxillary glands of the rat was examined. Dose-response curves showed that in the unoperated glands maximal secretory responses were obtained to an intravenous dose of 5-10 micrograms/kg of the tachykinins, that the amount of saliva secreted from the submaxillary gland was twice that from the parotid gland, and that physalaemin was more potent than substance P. Parasympathetic denervation of the parotid gland and decentralization of the submaxillary gland caused a marked sensitization to the tachykinins, as judged by lowered threshold doses for secretion and increased secretory responses to a series of submaximal doses 3 weeks postoperatively. Sensitization was less marked after sympathetic denervation and decentralization; in the parotid gland decentralization caused, in fact, no sensitization while in the submaxillary gland the degree of sensitization was about the same after the two types of operation. The tachykinins acted directly on the gland cells and the effect was not exerted via cholinergic, alpha-adrenergic or beta-adrenergic receptors. The pattern of sensitization to the tachykinins, found in the present study, after the different types of operation is similar to that previously found to cholinergic and alpha-adrenergic agonists and different from that to a beta-adrenergic agonist. Studies by others have shown that in the rat parotid gland peptidergic receptors share a common intracellular pathway with cholinergic and alpha-adrenergic receptors, whereas beta-adrenergic receptors use another pathway. In the present study it is suggested that this intracellular arrangement is of importance for the development of supersensitivity.

Adrenergic alpha-Agonists↗
PubMed1984

Development of supersensitivity to methacholine in the rat detrusor following either parasympathetic denervation or decentralization.

The male rat urinary bladder belongs to those few structures where both the post- and preganglionic parasympathetic nerves are accessible for severance. In the present study the sensitivity to the parasympathomimetic drug methacholine of muscle strips of either denervated or decentralized bladders was examined in vitro. One week postoperatively denervated and decentralized bladders were sensitized to the same degree, the ED50 values being 4 times less than ED50 of unoperated control bladders. In contrast to the decentralized bladders the supersensitivity in the denervated ones was found to have increased further when tested four weeks postoperatively, the ED50 value being about 20 times less than that of controls. The present findings are in agreement with Cannon's "law of denervation". The results are discussed in relation to possible mechanisms behind the phenomenon of supersensitivity.

Animals↗
PubMed2002

A stability analysis of a decentralized adaptive feedback active control system of sinusoidal sound in free space.

In some cases, the implementation of active control of sound in free space requires a large number of secondary sources and error sensors. In terms of control hardware, this may translate into considerable processing power requirement. A practical method to decrease processing power is to decentralize the control; that is, implement many single-input, single-output independent controllers operating simultaneously instead of a large multiple-input, multiple-output system. The main drawback of decentralized control is the risk of global instability. The purpose of this paper is to derive conditions under which globally stable control system behavior can be obtained in the case of adaptive feedback decentralized control for a sinusoidal disturbance. The main objective is to give practical conditions derived from the small gain theorem and the Nyquist criterion for the stability of the control system. These conditions only take into account the geometrical arrangement of the secondary sources and error sensors. This analysis involves a new parameter beta called "performance index," which is associated with both the convergence of the individual controllers and the global stability of the system. Simulation and experimental results are shown to illustrate the effectiveness of the developed analytical tools.

Feedback↗
PubMed1998

Comparison of decentration and tilt between one piece and three piece polymethyl methacrylate intraocular lenses.

BACKGROUND: The extent of the decentration and tilt was prospectively compared between one piece polymethyl methacrylate (PMMA) and three piece PMMA intraocular lenses (IOLs) which were implanted in the capsular bag after performing continuous curvilinear capsulorhexis. METHODS: 91 patients underwent a one piece PMMA IOL implantation in one eye as well as the implantation of the three piece PMMA IOL with polyvinylidene fluoride loops in the opposite eye. The length of the lens decentration and the angle of the tilt were quantitated using the anterior eye segment analysis system (EAS-1000) at 1 week as well as 1, 3, and 6 months postoperatively. RESULTS: The mean length of the decentration in the one piece IOL was smaller than that in the three piece IOL at 1 week (p = 0.0092), 1 month (p = 0.0044), 3 months (p = 0.0069), and 6 months (p = 0.0010) postoperatively. However, no significant difference was found in the degree of the tilt between the two types of IOLs throughout the observation periods. CONCLUSION: These results clarified that the one piece PMMA IOL with rigid PMMA haptics implanted in the capsular bag provides a better centration than the three piece PMMA IOL with flexible haptics, whereas the tilt was the same between the two types of IOLs.

Aged↗
PubMedDate not supplied

Decentration of posterior chamber IOL: effects of loop material and fixation technique.

A prospective study was conducted on 90 eyes undergoing extracapsular cataract extraction and posterior chamber IOL implantation. Postoperative IOL decentration was evaluated with respect to the loop material, either polypropylene (prolene) or polymethylmethacrylate (PMMA), and the IOL fixation technique, either in the capsular sac (in-the-bag) after capsulorhexis, or in the ciliary sulcus after "can-opener" capsulotomy. More decentration was observed with IOL having polypropylene loops than with those having PMMA loops (0.80 +/- 0.735 mm versus 0.373 +/- 0.299 mm). IOL implanted in the bag showed greater decentration than those implanted in the sulcus, but the difference was not significant. Our findings confirm the recommendation to use an IOL with PMMA loops when placing the implant in the capsular sac.

Aged↗
PubMed2005

Decentralized formation flying control in a multiple-team hierarchy.

In recent years, formation flying has been recognized as an enabling technology for a variety of mission concepts in both the scientific and defense arenas. Examples of developing missions at NASA include magnetospheric multiscale (MMS), solar imaging radio array (SIRA), and terrestrial planet finder (TPF). For each of these missions, a multiple satellite approach is required in order to accomplish the large-scale geometries imposed by the science objectives. In addition, the paradigm shift of using a multiple satellite cluster rather than a large, monolithic spacecraft has also been motivated by the expected benefits of increased robustness, greater flexibility, and reduced cost. However, the operational costs of monitoring and commanding a fleet of close-orbiting satellites is likely to be unreasonable unless the onboard software is sufficiently autonomous, robust, and scalable to large clusters. This paper presents the prototype of a system that addresses these objectives-a decentralized guidance and control system that is distributed across spacecraft using a multiple team framework. The objective is to divide large clusters into teams of "manageable" size, so that the communication and computation demands driven by N decentralized units are related to the number of satellites in a team rather than the entire cluster. The system is designed to provide a high level of autonomy, to support clusters with large numbers of satellites, to enable the number of spacecraft in the cluster to change post-launch, and to provide for on-orbit software modification. The distributed guidance and control system will be implemented in an object-oriented style using a messaging architecture for networking and threaded applications (MANTA). In this architecture, tasks may be remotely added, removed, or replaced post launch to increase mission flexibility and robustness. This built-in adaptability will allow software modifications to be made on-orbit in a robust manner. The prototype system, which is implemented in Matlab, emulates the object-oriented and message-passing features of the MANTA software. In this paper, the multiple team organization of the cluster is described, and the modular software architecture is presented. The relative dynamics in eccentric reference orbits is reviewed, and families of periodic, relative trajectories are identified, expressed as sets of static geometric parameters. The guidance law design is presented, and an example reconfiguration scenario is used to illustrate the distributed process of assigning geometric goals to the cluster. Next, a decentralized maneuver planning approach is presented that utilizes linear-programming methods to enact reconfiguration and coarse formation keeping maneuvers. Finally, a method for performing online collision avoidance is discussed, and an example is provided to gauge its performance.

Journal Article↗
PubMed2002

Method for optimizing the correction of the eye's higher-order aberrations in the presence of decentrations.

The use of a correcting element to compensate for higher-order aberrations in an optical system often requires accurate alignment of the correcting element. This is not always possible, as in the case of a contact lens on the eye. We propose a method consisting of partial correction of every aberration term to minimize the average variance of the residual wave-front aberration produced by Gaussian decentrations (translations and rotations). Analytical expressions to estimate the fraction of every aberration term that should be corrected for a given amount of decentration are derived. To demonstrate the application of this method, three examples are used to compare performance with total and with partial correction. The partial correction is more robust and always yields some benefit regardless of the amount of decentration.

Humans↗