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It is important that students understand the "open-ended" nature of scientific knowledge and the correct relationship between facts and theory. One way this can be taught is to examine a past controversy in which the interpretation of facts was contested. The controversy discussed here, with suggestions for teaching, is "Expanding Earth "versus" Sea Floor Spreading." Although this was a short and limited controversy within the mainstream scientific comrnunity, it has the advantage of having primary sources that are accessible to students to read for themselves. What makes this controversy intriguing is the later conversion of one of the protagonists (Tuzo Wilson) to tectonics. The controversy is framed explicitly in terms of several criteria for agreeing on the optimal theory: it is an exercise in what has been termed "theory choice" by Thomas Kuhn. Framing the controversy in this way can teach students a great deal about the emergence of scientific theories as well as criteria that can be used to judge ideas in a mature fashion.

Andrew Knoll, in his review of Ray Perman's The Genius of Time (September 9), a new biography of the philosopher-geologist James Hutton, emphasizes the discovery of Siccar Point on Scotland's [...]

This letter presents data concerning variation in average annual temperatures by altitude and latitude, along with some suggested class exercises.

Scientific statements are valid only within the confines of the approach and scale of study adopted at the outset of the inquiry. Therefore, geomorphological knowledge is considered to be valid only within the methodological and/or spatio-temporal framework adopted for study. New approaches add to understanding by changing the context within which phenomena are viewed but cannot invalidate existing concepts: these can be invalidated only if they are logically or empirically unsupported within their own frame of reference. Research programs may become self-fulfilling because it is only within their own context that hypotheses, with which they might be falsified, are generated and tested: indeed, and approach might not be capable of generating any falsifying hypotheses but be able to produce only hypotheses that are amenable to that particular mode of investigation. Therefore, contributions should be judged only within their own, stated methodological base and alternative approaches should be actively considered.

The origin of micro-relief on till sheets of the Conestogo Lake area, Ontario, is discussed. The micro-relief constitutes an extensive, integrated system of swales that represents a drainage network which functioned under periglacial conditions in the Late Wisconsinan. At many locations within the study area, this drainage exploited the micro-relief of polygonal patterned ground. The present low-order stream system has resulted from contraction of this Pleistocene system. A qualitative modification of Devries' Groundwater Outcrop Erosion Model is developed to explain drainage evolution at the Pleistocene-Holocene transition. Today, the swales are routes for surface and shallow sub-surface flow from the gently sloping interfluves of the study area. L'origine du microrelief des depots de moraines de fond dans la region du lac Conestogo, Ontario, est discutee. Le microrelief constitue un systeme de bas-fonds extensif et integre qui represente un reseau de drainage qui fonctionnait sous des conditions periglaciaires pendant le Wisconsinien superieur. Ce drainage a emprunte le microrelief des sols polygonaux a plusieurs endroits a l'interieur de la region d'etude. Le systeme actuel de rivieres de bas ordre est le resultat de la contraction de cet ancien systeme du Pleistocene. Une modification qualitative du modele de Devries d'erosion par affleurement de la nappe souterraine (Groundwater Outcrop Erosion Model) est developpee pour expliquer l'evolution du drainage pendant la transition Pleistocene-Holocene dans cette region. Aujourd'hui, les bas-fonds forment des routes pour le ruissellement et l'ecoulement hypodermique des interfluves a pentes douces de la region d'etude.

A 1-year-old male castrated Pug was referred for unilateral exophthalmos unresponsive to oral antibiotic and anti-inflammatory therapy. Clinical findings included exophthalmos of the left eye with lateral strabismus, resistance to retropulsion, and an elevated nictitans. Hematologic and biochemical analyses were within normal limits. Findings following computed tomography (CT) of the head included an expansile retrobulbar soft tissue mass with bony lysis extending into the left nasal cavity and nasopharynx. Ultrasound-guided fine-needle aspirates and biopsy samples obtained via rhinoscopy were nondiagnostic. Palliative exenteration was elected; the patient was euthanized 13 weeks following exenteration due to development of neurologic signs and perceived poor quality of life. The histopathologic diagnosis was a malignant pigmented peripheral nerve sheath tumor. [ABSTRACT FROM AUTHOR]

A 7-year-old Connemara stallion was presented with a 4 month history of blepharospasm, recurrent corneal ulcerations, mucopurulent ocular discharge, and keratoconjunctivitis sicca (KCS) in both eyes unresponsive to medical therapy. Ophthalmic examination revealed lackluster corneas, axial corneal scarring and pigmentation with associated neovascularization, and absolute KCS in both eyes. Computed tomography scan and endoscopic evaluation of the upper airway and guttural pouches revealed no structural abnormalities to indicate neurogenic KCS. The stallion was diagnosed with immune-mediated dacryoadenitis as all other causes of KCS were excluded. Parotid duct transposition (PDT) was performed in the right eye followed by PDT in the left eye 4 weeks later. The right PDT was functional 2 years post-operatively with significant improvement in ocular comfort and reduced corneal fibrosis and neovascularization. The left PDT developed a salivary-cutaneous fistula over the left masseter muscle post-operatively due to avascular necrosis of the distal parotid duct (PD). Surgical reconstruction of the PDT using an expanded-polytetrafluoroethylene (e-PTFE) tube graft, an e-PTFE tube graft to autogenous caudal auricular vein graft, and an autogenous saphenous vein graft were all unsuccessful. Tear production in the left eye improved at 1 year post-surgery as a result of long term lacrostimulant therapy, and a permanent PD-cutaneous fistula was performed on the left PD at the level of the ventral mandible. Bilateral PDT in the horse is effective in resolving clinical signs associated with KCS; however, morbidity associated with avascular necrosis of the transposed PD may be significant and can result in surgical failure. [ABSTRACT FROM AUTHOR]

Hypoactive sexual desire disorder (HSDD) and sexual aversion disorder (SAD) are an under-diagnosed group of disorders that affect men and women. Despite their prevalence, these two disorders are often not addressed by healthcare providers and patients due their private and awkward nature. As physicians, we need to move beyond our own unease in order to adequately address our patients' sexual problems and implement appropriate treatment. Using the Sexual Response Cycle as the model of the physiological changes of humans during sexual stimulation and the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition this article will review the current literature on the desire disorders focusing on prevalence, etiology, and treatment.