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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.

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]

Objective To evaluate the success rate and outcome of trans-corneal reduction of anterior lens luxation ( TR- ALL) in dogs with lens instability. Animals Studied Nineteen dogs with anterior lens luxation. Procedures Medical records of dogs with anterior lens luxation ( ALL) were reviewed: dogs were included if TR- ALL was performed followed by medical therapy in the form of topical 0.005% latanoprost ophthalmic solution. The duration of ALL, vision status, ophthalmic examination abnormalities, reason for performing TR- ALL and details of TR- ALL were recorded. Success rate for TR- ALL as well as postprocedure complications were also assessed. Results Twenty eyes from 19 dogs met the inclusion criteria. Median age was 6.5 years (0.3-15 years) and 47% were terriers (9/19). Successful TR- ALL was achieved in 85% of eyes (17/20); failure was attributed to posterior synechia or vitreous expansion. Short-term complications included corneal ulceration (2/20) and anterior uveitis (3/20); recurrence of anterior luxation occurred in only one dog. Median follow-up for visual eyes (11) following successful TR- ALL was 353 days (range of 1 to 1182 days). Vision was retained in 54.5% (6/11) of eyes with a median time to vision loss of 12 months as a result of glaucoma or presumed retinal detachment. Conclusions Trans-corneal reduction of ALL provides a non-surgical alternative to intracapsular lens extraction (visual eyes) or enucleation (nonvisual eyes) in dogs. Long-term visual outcome of TR- ALL is comparable to intracapsular lens extraction for ALL. [ABSTRACT FROM AUTHOR]

Objective To review the clinical features, treatments, complications, and outcomes of horses with traumatic orbital fractures. Study design Retrospective study. Sample Population Eighteen horses with confirmed orbital fractures. Procedures Medical records of horses presenting with orbital fractures between 2006 and 2013 were reviewed. Signalment, etiology of fracture, clinical signs, fracture descriptions, diagnostic imaging, treatments, complications, and outcomes were evaluated. Results Eighteen horses presented with orbital fractures resulting from rearing in a confined space ( n = 5), being kicked (4), colliding with a stationary object (3), and unknown trauma (6). Radiography and computed tomography were effective at classifying fractures and evaluating sinus/nasal involvement. Epistaxis/sinusitis were associated with fractures of the zygomatic process of the temporal bone ( n = 3) and comminuted fractures of multiple bones (5). Seventeen fractures required treatment, with fifteen receiving a combination of medical and surgical therapy. Surgery included reduction of large bony fragments ( n = 8), removal of small fragments (12), stabilization with a wire implant (1), and sinus trephination and lavage (5). Factors contributing to a favorable outcome included: globe retention ( n = 16), vision (14), comfort (15), cosmesis (9), and return to previous function (13). Conclusions Horses sustaining orbital fractures treated promptly with medical and surgical therapy have a favorable prognosis for return to function and cosmesis. Fractures affecting the zygomatic process of the frontal bone are unlikely to involve the sinus/nasal cavities. Epistaxis and sinusitis warrant more aggressive therapy and decrease functional and cosmetic outcome. [ABSTRACT FROM AUTHOR]

Objective--To describe clinical, microbiological, in vivo confocal microscopic, and histo-pathologic features of fungal keratitis in alpacas and to estimate prevalence of the disease in a population of alpacas from the northeastern United States. Design--Retrospective case series. Animals--11 alpacas. Procedures--Medical records of alpacas evaluated by the ophthalmology service of a vet-erinary teaching hospital were searched to identify animals with a clinical diagnosis of fungal keratitis and positive results for fungal culture of a corneal sample between 2003 and 2012. Signalment and historical, clinical, and microbiological details were recorded. Results of cytologic, histopathologic, and in vivo confocal microscopic corneal examinations were collected when available. Results--Fungal keratitis was diagnosed in 11 of 169 (6.5%) alpacas that underwent ophthalmologic examination by the ophthalmology service during the study period. Ten of the 11 alpacas were evaluated in the summer or fall months. Corneal lesions included stromal ulcer, stromal abscess, corneal perforation, and nonulcerative keratitis. Aspergillus fumigatus and Fusarium solarii were the most frequently cultured fungi. Fungi were also identified through corneal cytologic examination, histologic examination, or in vivo confocal microscopy in 9 alpacas. Historically, 2 alpacas were evaluated following external ocular trauma and 1 following corneal foreign body removal. Nine alpacas had received topical treatment with antimicrobials and 2 had antimicrobial-corticosteroid combinations administered topically prior to referral. Nine of 10 alpacas for which follow-up information was available were successfully treated, with globe and vision retention. Conclusions and Clinical Relevance--Fungal keratitis was a relatively common ocular disease in this population of alpacas and appeared to share several clinical features with keratomycosis in horses. [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]

Objective To perform a randomized, placebo-controlled, masked clinical trial using a cross-over design to determine the effect of oral diphenhydramine on aqueous tear production in normal dogs. Animals studied Seventeen dogs with normal ophthalmic examinations. Procedures Baseline tear production was established for each dog by performing Schirmer tear test I (STT I). Dogs received 20-day treatment courses of both oral diphenhydramine and placebo solutions with a 10-day washout period between treatment periods. Each dog was randomly assigned to receive diphenhydramine or placebo at the outset of the study. Measurements of STT I values were measured at regular intervals during the study and were conducted at the same time of day throughout the study to control for diurnal variations in tear production. The significance of the impact of diphenhydramine treatment on the quantity of aqueous tear production, as determine by STT results over time, was evaluated using regression analysis with appropriate transformation. Results Statistical comparisons at each measurement time, including baseline measurements between control and treatment groups, revealed no significant differences. Mean STT I levels also did not differ significantly at any measurement time compared to baseline for treatment or control groups. Conclusions Short-term administration of oral diphenhydramine does not result in a significant decrease in aqueous tear production in normal dogs. [ABSTRACT FROM AUTHOR]

A PPM-focused TWT for airborne applications producing over 400 W of peak RF output power at 90.6 GHz and average-power levels between 150 and 180 W is described. Design goals of 1% bandwidth, 250 W of peak power, and 30 dB of gain have all been met despite the invariable fabrication errors in this nascent type of tube. The TWT utilizes a novel integral-pole-piece ferruleless-coupled-cavity-class folded-waveguide circuit that features thick iron pole pieces with hollowed out centers, and a gridded gun for fast beam modulation. This thermally robust circuit plus the tetrode gun represent two key enabling technologies for compact high-average-power TWTs in W-band. [ABSTRACT FROM AUTHOR]

Objective To describe feline periocular cutaneous mast cell tumor (CMCT) clinical features, rates of local tumor recurrence and metastases, and cat survival time following surgical excision. Animals studied Thirty-three cats with periocular CMCTs. Procedures Medical records of cats diagnosed with periocular CMCTs were reviewed; cats were included if CMCTs were surgically excised and the diagnosis confirmed by histopathology. The appearance, size, location and histopathology findings of CMCTs were recorded. Rates of local recurrence, metastasis, and survival time following surgical excision were collected when available. Results All periocular CMCTs were restricted to the eyelids. In addition to surgical excision, three cats were treated with adjunctive therapy (strontium-90 irradiation or cryotherapy) intraoperatively. Local tumor control was achieved in 22/23 cats with a minimum follow-up of 30 days (median follow-up time of 711 days); one cat developed disseminated CMCTs but no local recurrence. Cats with periocular CMCTs had a median survival time of 945 days. Metastatic disease involving peripheral lymph nodes or abdominal viscera was not detected in any cat at any time during the study. All periocular CMCTs were classified as low-grade based on histopathology, and complete excision was achieved in approximately 50% of cases. Conclusions Surgical excision of periocular CMCTs in cats is an effective treatment option with rare local recurrence and metastases, even following incomplete surgical excision. [ABSTRACT FROM AUTHOR]

Objective To evaluate dogs with amaurosis and compare signalment, history, ophthalmic examination and neurologic abnormalities between dogs diagnosed with sudden acquired retinal degeneration syndrome (SARDS) versus neurological disease (ND). Animals Studied-140 dogs with acute vision loss and ocular abnormalities insufficient to account for visual deficits. An electroretinogram (ERG) was performed on each dog. Procedures Medical records were reviewed and information was collected for all dogs meeting the inclusion criteria. Dogs diagnosed with SARDS were compared to those with ND based on signalment, duration of clinical signs, past medical problems, clinicopathologic findings, and ophthalmic and physical examination abnormalities. Results 120 dogs were diagnosed with SARDS and 20 dogs with ND based on ERG results. Mixed-breed dogs were most commonly diagnosed with SARDS as well as ND. Pure breed dogs frequently diagnosed with SARDS included the Miniature Schnauzer and Dachshund. Dogs with SARDS did not differ significantly from those with ND based on age or sex distribution. Cushing's-like symptoms were reported more frequently in SARDS dogs as well as conjunctival hyperemia and retinal vascular attenuation. Papilledema and asymmetric visual deficits were observed more frequently in dogs with ND. Dogs with ND were no more likely than SARDS dogs to have additional neurological deficits. Conclusions Appreciable overlap of clinical signs exists between dogs with SARDS and dogs with ND resulting in acute vision loss. As a significant portion of dogs (14%) in the present study were diagnosed with ND, an ERG to rule out ND is indicated in dogs with amaurosis. [ABSTRACT FROM AUTHOR]

The concept of the rock cycle and the "indefinite" length of geologic time were outlined first by James Hutton before he had ever seen an unconformity. Hutton drew general support of his theory from existing observations of unconformities from accounts in French, which he re-interpreted in light of his own ideas. Hutton then found his own field examples to test his ideas before coming upon Siccar Point. In summing up his evidence, which included wide-ranging observations on the geology of SE Scotland, Hutton himself did not cite Siccar Point. Inaccuracies concerning the role of Siccar Point in the development of James Hutton's ideas remain as entrenched as ever in many physical geology textbooks. A more balanced appraisal of all contributions to Hutton's work is warranted, particularly the contributions, of French, writers. Finally, an accurate presentation of Hutton's method can contribute to students' understanding of the nature of historical theories and in meeting the challenges of creationists. [ABSTRACT FROM AUTHOR]

OBJECTIVE To evaluate signalment, clinical signs, treatment, and factors affecting visual prognosis in dogs with uveodermatologic syndrome (UDS). DESIGN Retrospective case series and nested cohort study. ANIMALS 50 dogs (37 Akitas and 13 non-Akitas) with UDS evaluated at 4 ophthalmology practices. PROCEDURES Data were collected from the medical records regarding signalment, clinical signs, biopsy results, medications, adverse effects, vision and glaucoma status at initial and subsequent examinations, and duration of follow-up. Various factors were examined for associations with development of blindness or glaucoma following initial examination. RESULTS The most common ophthalmic signs included aqueous flare (n = 35 [70%]), iris abnormalities (29 [58%]), retinal detachment (23 [46%]), and choroidal depigmentation or chorioretinal infiltrates (10 [20%]). At initial examination, 36% (18/50) of dogs had glaucoma and 57% (26/46) were blind in both eyes. Twenty-five (50%) dogs had vision at their final visit, representing 78% of the 32 dogs that had vision at initial examination or regained vision during the follow-up period. In dogs that lost vision, median time to permanent blindness in both eyes was 13.5 months (range, 0.4 to 59 months) after initial examination. No significant associations with time to glaucoma or vision loss were identified for signalment variables, specific medications, or duration of clinical signs prior to initial examination. CONCLUSIONS AND CLINICAL RELEVANCE UDS commonly resulted in glaucoma, vision loss, or both in affected dogs. No evaluated factor was associated with visual prognosis; however, a subset of patients maintained vision through to the final recheck examination. [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.