Peter Lynch

Hidradenitis suppurativa: A comprehensive review

Hidradenitis suppurativa, also known as acne inversa, is a chronic, often debilitating disease primarily affecting the axillae, perineum, and inframammary regions. Prevalence rates of up to 4% have been estimated. Our understanding of the disease has changed over time. It is now considered a disease of follicular occlusion rather than an inflammatory or infectious process of the apocrine glands. Clinically, the disease often presents with tender subcutaneous nodules beginning around puberty. The nodules may spontaneously rupture or coalesce, forming painful, deep dermal abscesses. Eventually, fibrosis and the formation of extensive sinus tracts may result. The location of the lesions may lead to social embarrassment and the failure to seek medical treatment. Therapies in the past have consisted of long-term antibiotics, antiandrogens, and surgery. New treatments like tumor necrosis factor-alfa inhibitors have given clinicians more options against this difficult disease.

The vulvodynia guideline

Objective. To provide a review of the literature and make known expert opinion regarding the treatment of vulvodynia. Materials and Methods. Experts reviewed the existing literature to provide new definitions for vulvar pain and to describe treatments for this condition. Results. Vulvodynia has been redefined by the International Society for the Study of Vulvovaginal Disease as vulvar discomfort in the absence of gross anatomic or neurologic findings. Classification is based further on whether the pain is generalized or localized and whether it is provoked, unprovoked, or both. Treatments described include general vulvar care, topical medications, oral medications, injectables, biofeedback and physical therapy, dietary changes with supplementations, acupuncture, hypnotherapy, and surgery. No one treatment is clearly the best for an individual patient. Conclusions. Vulvodynia has many possible treatments, but very few controlled trials have been performed to verify efficacy of these treatments. Provided are guidelines based largely on expert opinion to assist the patient and practitioner in dealing with this condition.

Initialization of the HIRLAM Model Using a Digital Filter

Abstract Spurious high-frequency oscillations occur in forecasts made with the primitive equations if the initial fields of mass and wind are not in an appropriate state of balance with each other. These oscillations are due to gravity-inertia waves of unrealistically large amplitude; the primary purpose of initialization is the removal or reduction of this high-frequency noise by a delicate adjustment of the analyzed data. In this paper a simple method of eliminating spurious oscillations is presented. The method uses a digital filter applied to time series of the model variables generated by short-range forward and backward integrations from the initial time. The digital filtering technique is applied to initialize data for the High-Resolution Limited-Area Model (HIRLAM). The method is shown to have the three characteristics essential to any satisfactory initialization scheme: (i) high-frequency noise is effectively removed from the forecast; (ii) changes made to the analyzed fields are acceptably small...

The origins of computer weather prediction and climate modeling

Numerical simulation of an ever-increasing range of geophysical phenomena is adding enormously to our understanding of complex processes in the Earth system. The consequences for mankind of ongoing climate change will be far-reaching. Earth System Models are capable of replicating climate regimes of past millennia and are the best means we have of predicting the future of our climate. The basic ideas of numerical forecasting and climate modeling were developed about a century ago, long before the first electronic computer was constructed. There were several major practical obstacles to be overcome before numerical prediction could be put into practice. A fuller understanding of atmospheric dynamics allowed the development of simplified systems of equations; regular radiosonde observations of the free atmosphere and, later, satellite data, provided the initial conditions; stable finite difference schemes were developed; and powerful electronic computers provided a practical means of carrying out the prodigious calculations required to predict the changes in the weather. Progress in weather forecasting and in climate modeling over the past 50 years has been dramatic. In this presentation, we will trace the history of computer forecasting through the ENIAC integrations to the present day. The useful range of deterministic prediction is increasing by about one day each decade, and our understanding of climate change is growing rapidly as Earth System Models of ever-increasing sophistication are developed.

The Fronts and Atlantic Storm-Track Experiment (FASTEX): Scientific Objectives and Experimental Design

The Fronts and Atlantic Storm-Track Experiment (FASTEX) will address the life cycle of cyclones evolving over the North Atlantic Ocean in January and February 1997. The objectives of FASTEX are to improve the forecasts of end-of-storm-track cyclogenesis (primarily in the eastern Atlantic but with applicability to the Pacific) in the range 24 to 72 h, to enable the testing of theoretical ideas on cyclone formation and development, and to document the vertical and the mesoscale structure of cloud systems in mature cyclones and their relation to the dynamics. The observing system includes ships that will remain in the vicinity of the main baroclinic zone in the central Atlantic Ocean, jet aircraft that will fly and drop sondes off the east coast of North America or over the central Atlantic Ocean, turboprop aircraft that will survey mature cyclones off Ireland with dropsondes, and airborne Doppler radars, including ASTRAIA/ELDORA. Radiosounding frequency around the North Atlantic basin will be increased, as ...

The Dolph-Chebyshev Window: A Simple Optimal Filter

Analyzed data for numerical prediction can be effectively initialized by means of a digital filter. Computation time is reduced by using an optimal filter. The construction of optimal filters involves the solution of a nonlinear minimization problem using an iterative procedure. In this paper a simple filter based on the Dolph‐Chebyshev window, which has properties similar to those of an optimal filter, is described. It is shown to be optimal for an appropriate choice of parameters. It has an explicit analytical expression and is easily implemented. Its effectiveness is demonstrated by application to Richardson’s forecast: the initial pressure tendency is reduced from 145 hPa pe r6ht o 20.9 hPa per 6 h. Use of the filter is not restricted to initialization; it may also be applied as a weak constraint in four-dimensional data assimilation.

Lichen simplex chronicus (atopic/neurodermatitis) of the anogenital region.

ABSTRACT:  Lichen simplex chronicus (LSC) of the anogenital area is an eczematous disease characterized by unremitting itching and scratching. In most instances, it arises in individuals who are genetically atopic, and as such, LSC can be viewed as a localized variant of atopic/neurodermatitis. Common triggers for the development of the disease include psychological distress, and local environmental problems such as heat, sweating, and excess dryness. Lichen simplex chronicus may also develop as a superimposed condition in the presence of other anogenital diseases such as candidiasis, psoriasis, lichen sclerosus, tinea cruris, and neoplasia. Lichen simplex chronicus frequently persists as an itch‐scratch cycle, even when environmental triggers are removed and the underlying disease is treated. For this reason, successful therapy requires attention not only to trigger factors, but also to repair of the damaged barrier layer, reduction in inflammation, and breakup of the itch‐scratch cycle.

Diabatic Digital-Filtering Initialization: Application to the HIRLAM Model

Abstract A digital-filtering initialization scheme, which includes the effects of diabatic processes, has been formulated. This scheme gives a lower noise level in the forecast and a better organized initial pressure-tendency field than for the corresponding adiabatic initialization. The implementation of the scheme is very easy, requiring only the calculation of the filter coefficients and minor adjustments to the model code. The computational expense of the digital-filtering initialization is directly proportional to the length of the time span over which the filter is applied. By a careful choice of filter weights, based on optimal filter theory, the span of the filter can be reduced by a factor of 2 or 3, with a corresponding increase in efficiency.

Improving the Efficiency of a Digital Filtering Scheme for Diabatic Initialization

A method of diabatic initialization is described in which a nonrecursive digital filter is applied to both the backward (adiabatic) and forward (diabatic) steps. It has clear advantages over previously proposed schemes: the initialization requires significantly less computation time and the resulting changes in the analyzed fields are consistently smaller. Despite these smaller increments, the suppression of spurious high-frequency noise is at least as effective as for the earlier schemes.

Deducing the Wind from Vorticity and Divergence

Abstract The horizontal wind field may be deduced from the vorticity and divergence by solving Poisson equations for the velocity potential and streamfunction or, more directly, by the solution of a single Poisson equally accurate. If the domain is of limited extent, boundary conditions must be specified. It is sufficient to prescribe a single component of the boundary velocity. Methods which use both components overdetermine the solution and may not converge in general.