Looking down: a model for visual route following in flying insects.

Insect visual navigation is often assumed to depend on panoramic views of the horizon, and how these change as the animal moves. However, it is known that honey bees can visually navigate in flat, open meadows where visual information at the horizon is minimal, or would remain relatively constant across a wide range of positions. In this paper we hypothesise that these animals can navigate using view memories of the ground. We find that in natural scenes, low resolution views from an aerial perspective of ostensibly self-similar terrain (e.g. within a field of grass) provide surprisingly robust descriptors of precise spatial locations. We propose a new visual route following approach that makes use of transverse oscillations to centre a flight path along a sequence of learned views of the ground. We deploy this model on an autonomous quadcopter and demonstrate that it provides robust performance in the real world on journeys of up to 30 m. The success of our method is contingent on a robust view matching process which can evaluate the familiarity of a view with a degree of translational invariance. We show that a previously developed wavelet based bandpass orientated filter approach fits these requirements well, exhibiting double the catchment area of standard approaches. Using a realistic simulation package, we evaluate the robustness of our approach to variations in heading direction and aircraft height between inbound and outbound journeys. We also demonstrate that our approach can operate using a vision system with a biologically relevant visual acuity and viewing direction.

Predictors of hematological abnormalities in multiple sclerosis patients treated with fingolimod and dimethyl fumarate and impact of treatment switch on lymphocyte and leukocyte count.

BACKGROUND: There is limited data regarding the predictors of hematological abnormalities in multiple sclerosis (MS) patients treated with dimethyl fumarate (DMF) or fingolimod (FNG), and the impact of treatment switch on lymphocyte and leukocyte count METHODS: We identified 405 patients on DMF and 300 patients on FNG (treatment duration: at least 12 month) within a large prospective study of MS patients conducted at the Partners MS Center, Brigham and Women's Hospital (CLIMB study) between Jan 2011 to Feb 2016. Patients had complete blood counts with differentials at baseline and every 6 months while on treatment. Most participants had a clinical visit with complete neurologic examinations every 6 months and brain MRI scan every 12 months. T cell subset profile was available for subgroup of patients (n = 116). RESULTS: In the FNG group, the risk of developing lymphopenia grade 4 (< 200) was higher in female patients (p = 0.0117) and those who were previously treated with natalizumab (p = 0.0116), while the risk of lymphopenia grade 3b+4 (< 350) was higher in female patients (p = 0.0009). DMF treated patients with lower baseline lymphocyte count had a higher chance of developing lymphopenia grade 2 (< 800) (p < 0.0001) or 2+3 (< 500) (p < 0.0001). We examined the effect of treatment switch between DMF and FNG. No significant recovery in lymphocyte and leukocyte count was observed after treatment switches. Reduced dosing of FNG in patients with lymphopenia led to increase in lymphocyte count but also increased disease activity in 25% of patients. CONCLUSION: Female sex and prior exposure to natalizumab increased the probability of lymphopenia on FNG, while low absolute lymphocyte count was associated with increased risk of lymphopenia on DMF. Parallel switch did not lead to recovery from hematological abnormalities. Long-term studies with larger number of patients are required to confirm our findings and to establish guidelines for prediction and management of hematological abnormalities.

Fatigue-crack growth properties of thin-walled superelastic austenitic Nitinol tube for endovascular stents.

Over the past 10 years, the supereleastic nickel-titanium alloy Nitinol has found widespread application in the manufacture of small-scale biomedical devices, such as self-expanding endovascular stents. Although conventional stress/strain-life (S/N) analyses are invariably used as the primary method for design against fatigue loading and for predicting safe lifetimes, fracture mechanics-based methodologies provide a vital means of assessing the quantitative effect of defects on such lifetimes. Unfortunately, fracture mechanics studies on fatigue in Nitinol are scarce, and most results do not pertain to the (thin-walled tube) product forms that are typically used in the manufacture of endovascular stents. In the current work, we document the basic fatigue-crack growth properties of flattened thin-walled ( approximately 400 microm thick) Nitinol tubing in a 37 degrees C air environment. Crack-growth behavior is characterized over a wide range of growth rates ( approximately 6 orders of magnitude) and load ratios, that is, as a function of the alternating and maximum stress intensities, at 50 Hz. Limited experiments at both 5 and 50 Hz were also performed in 37 degrees C air and simulated body fluid to determine whether the cyclic frequency affects the fatigue behavior. Fatigue-crack growth-rate properties in such thin-walled Nitinol tube are found to be quite distinct from limited published data on other (mainly bulk) product forms of Nitinol, for example, bar and strip, both in terms of the relative fatigue thresholds and the variation in steady-state growth rates.

Can we talk about CD4+CD28- lymphocytes as a risk factor for ischemic stroke?

BACKGROUND: CD4+CD28- lymphocytes are implicated in the destabilization of atheromatous plaque, leading to acute coronary episodes. One may ask whether these cells play a similar role in ischemic stroke pathogenesis with an atherosclerotic background. METHODS: Flow cytometry was applied to determine the percentage of CD4+CD28- lymphocytes in the peripheral blood of patients during the acute phase of their first ischemic stroke (group I) and in patients without a history of stroke but with two of the most important risk factors (hypertension, diabetes) for atherosclerosis-related ischemic stroke (group II). The results were compared with healthy controls. RESULTS: The median percentages of CD4+CD28- lymphocytes in groups I and II did not differ significantly, but for each of these groups the percentage was higher than in the control group. The time of blood sampling from onset of stroke, presence of the ischemic focus in the CT brain scan and severity of neurological deficits did not correlate with the percentage of CD4+CD28- lymphocytes. CONCLUSIONS: We conclude that CD4+CD28- lymphocytes are implicated in mechanisms enhancing the risk of acute ischemic stroke and not a consequence of stroke.

Endoscopic closure of postsurgical anterior cranial fossa cerebrospinal fluid leaks.

OBJECTIVE: The primary objective of this study is to present an alternative technique to closure of anterior cranial fossa cerebrospinal fluid (CSF) leaks. This study also serves to review our experience with our technique and presents some technical "tricks" we have learned through experience. METHODS: The design of this study is a clinical chart review. The setting is an academic medical center. RESULTS: Eight patients were referred for closure of postsurgical CSF leaks. Seven of eight patients underwent closure with one attempt and closure was achieved after a second attempt in one patient. Follow-up ranged from 1.5 to 4.0 years. There were no complications. No patient developed an acute or delayed episode of meningitis. CONCLUSION: The technique of endoscopic closure of a CSF leak is a safe and effective means for closure of a postsurgical anterior cranial fossa CSF fistula when performed by an experienced operator.

Studies on derivatives of 2-amino-4-p-chlorophenylthiazole-5-acetic acid. IV. Addition reactions of thioglycolic acid to 2-N-aralkylidene derivatives of 2-amino-4-p-chlorophenylthiazole-5-acetic acid.

In the course of studies on compounds with expected antiinflammatory and immunosuppressive activity a series of new derivatives of 2-amino-4-p-chlorophenylthiazole-5-acetic acid have been synthesized. Several new and unexpected details of the chemical properties of these compounds were revealed. The chemical structure of the new compounds was confirmed by degradation and identification of the decomposition products and by spectral analysis.

Studies on derivatives of 2-amino-4-p-chlorophenylthiazole-5-acetic acid. VI. Syntheses and properties of 2-N-aralkyl-alpha-sulphoderivatives of tert-amides of 2-amino-4-p-chlorophenylthiazole-5-acetic acid.

In the course of the studies on compounds with expected antiinflammatory and immunosuppressive activity several new tert-amides derivatives of 2-N-aralkylamino-alpha-sulpho-2-amino-4-p-chlorophenylthiazole-5-acetic acid were synthesized. Some of the previously described Schiff bases reacted with aqueous alcoholic solution of sodium bisulphite and as a result several (III-VIII) alpha-sulphoderivatives were obtained. The course of the reactions was studied and the structure of the new compounds was confirmed.

Synthesis of derivatives of 2-amino-4-p-chlorophenylthiazole-5-acetic acid.

In the course of studies on compounds with expected antiinflammatory and immunosuppressive action a number of new derivatives of 2-amino-4-p-chlorophenylthiazole-s-acetic acid have been synthetized. The chemical structure of these compounds has been confirmed by elemental analysis and IR spectra. The newly obtained compounds were investigated pharmacologically. It has been found that some of the derivatives possess antiinflammatory and immunosuppressive activity.

Studies on derivatives of 2-amino-4-p-chlorophenylthiazole-5-acetic acid. V. Syntheses of 2-N-aralkylidene and 2-N-aralkyl derivatives of 2-amino-4-p-chlorophenylthiazole-5-acetic acid.

A number of new N-aralkylidene and N-aralkyl derivatives of amides and hydrazides of 2-amino-4-p-chlorophenylthiazole-5-acetic acid (III-XXIX) have been synthesized. These compounds were obtained in two various ways depending on the character of substituents in the carboxyl group. The chemical structure of the newly obtained compounds was determined on the basis of the data of elementary and spectral analyses.

Studies on the derivatives of 2-amino-4-p-chlorophenylthiazole-5-acetic acid. I. Syntheses and pharmacological analysis of acylderivatives of 2-amino-4-p-chlorophenylthiazole-5-acetic acid.

A number of new acyl and imidoderivatives of 2-amino-4-p-chlorophenylthiazole-5-acetic acid (II) and its methyl ester (VII) were synthesized. Methyl ester VII heated in benzene solution with acid anhydrides was transformed into adequate acyl derivatives (VIII, IX, X, XIII, XVI). Some of them (X, XIII, XVII) by heating with acetic anhydride underwent cyclization and were transformed into the imido derivatives (XI, XIV, XVIII). Compounds XI, XIV and XVI heated with diluted aqueous solution of sodium hydroxide underwent selective hydrolysis giving the respective dicarboxylic acids XII, XV, XVII. Pharmacological analysis revealed that some of the synthesized preparations exert an anti-inflammatory effect and allow to draw limited relations between chemical structure and pharmacological activity in this group of compounds.

Studies on the derivatives of thiazole acetic acid. II. Syntheses and pharmacological analysis of 2-N-aralkylidene and 2-N-aralkyl derivatives of 2-amino-4-p-chlorophenylthiazole-5-acetic acid.

A number of 2-N-aralkylidene, 2-N-aralkyl and 2-N-aralkyl-alpha-sulphoderivatives of 2-amino-4-p-chlorophenylthiazole-5-acetic acid (I, R = H) and its methyl ester (I, R = CH3) were synthesized. As a result of condensation of methyl ester I with various aromatic aldehydes in boiling benzene solution, the Schiff-bases (anils) II--VIII were obtained. After reduction with NaBH4 compounds II--VIII were transformed into adequate amino esters IX--XV. Esters IX--XV heated with diluted aqueous solution of sodium hydroxide underwent selective hydrolysis giving the respective amino acids XVI--XXII. Some of Schiff bases (II, III, V, VII, VIII) reacted with aqueous alcoholic solution of sodium bisulphite after its several (XXIII--XXVII). alpha-sulphoderivatives had been obtained. Several tests were performed in order to detect the anti-inflammatory and immunosuppressive activity of the compounds. The pharmacological analysis allowed us to draw conclusions concerning the relationship between chemical structure and biological activity in this group of compounds. The most efficacious immunosuppressive and anti-inflammatory activity exhibited 2-aralkyl-alpha-sulphoderivatives.

Cerebrospinal fluid fistula and endoscopic sinus surgery.

Seven cases of cerebrospinal fluid fistulae occurring as a result of endoscopic sinus surgery in a total of 800 ethmoidectomies are discussed, along with 1 case referred for consultation. One cerebrospinal fluid fistula was intrasphenoid, 4 were posterior ethmoid/base of skull, 2 were anterior ethmoid, and 1 was ethmoid cribriform. Six of 8 fistulae were closed endoscopically. The sphenoid sinus cerebrospinal fluid fistula was closed successfully with fibrin glue and Gelfoam. Five cerebrospinal fluid fistulae were closed successfully using fascia, muscle, and Gel-foam. Two cerebrospinal fluid fistulae were treated conservatively, and only 1 stopped. Anatomic and technical aspects related to the occurrence of cerebrospinal fluid fistulae are discussed. Management and treatment of cerebrospinal fluid fistulae occurring during and after endoscopic sinus surgery is emphasized. When identified intraoperatively or delayed, cerebrospinal fluid fistulae can be managed successfully by endoscopic technique.

Complications of endoscopic intranasal ethmoidectomy.

A consecutive series of 90 patients undergoing endoscopic intranasal ethmoidectomy was reviewed. There were 26 complications (29%) in 19 patients in this group. Eight complications (8%) including CSF leak, temporary blindness, and hemorrhage were considered major with the latter occurring most commonly. Synechiae were the most commonly occurring minor complications. Endoscopic nasal sinus surgery performed by inexperienced operators carries with it the same risks and complications as traditional intranasal sinus surgery. Any surgeon who does not routinely perform traditional intranasal ethmoidectomy should accrue endoscopic experience through appropriate didactic training and multiple cadaver dissections (akin to otologic training).

Complications in endoscopic intranasal ethmoidectomy: an update.

A previous publication by this author discussing complications of endoscopic intranasal ethmoidectomy indicated an overall complication rate of 29% in 90 patients (17% in 150 ethmoidectomies). Compared to published complications rates for traditional intranasal ethmoidectomy (2.7% to 3.7%), 17% is alarming and of concern. The complication results in 300 ethmoidectomies performed on 180 patients are presented. The overall complication rate was 9.3%. Only two further complications have occurred since the first reported series: a cerebrospinal fluid leak and one case of subcutaneous emphysema. Methods and techniques that have led to the reduction of complications are briefly discussed. Endoscopic ethmoidectomy is a valid, safe procedure in experienced hands.

Endoscopic sizing: an attempt at uniformity.

The inside and outside diameters of all endoscopes and tracheotomy tubes in the endoscopy suite were systematically measured. These measurements were correlated with the manufacturer's stated size and comparisons noted. A lack of uniformity was noted often among and between all product lines. In addition, endoscopes and tracheotomy tubes were not uniformly labeled with inside and outside diameters. As a result, the proper choice of a tracheotomy tube or endoscope for a patient's size and age may be confusing. A chart was developed and included in order to allow quick and accurate recognition of tracheotomy tube and endoscope sizes across product lines to aid in the proper selection of tracheotomy tubes and endoscopic equipment.

Clinical accuracy of tuning fork tests.

A review of the literature reveals a surprisingly sparse amount of true documentation concerning the validity of using tuning forks as an adjunctive measure in the diagnosis of hearing impairment. Most reports are historical or anecdotal. With this in mind, a protocol was set up to identify the value of three standard tuning fork tests--the Rinne, the Weber, the Bing Occlusion--at frequencies of 256, 512 and 1024 Hz. The data were compared to otologic examination, audiometry and acoustic impedance. Results indicate the Rinne, Weber and Bing Occlusion tests do not accurately predict the type of hearing impairment as frequently as the literature suggests.

Malignant hyperpyrexia: an update for the otolaryngologist.

Malignant hyperpyrexia (MH) is a syndrome with a mortality of 60%, triggered by a broad variety of anesthetic agents. The most significant recent advance influencing the clinician's ability to safely manage MH individuals is the emergence of dantrolene sodium as both a prophylactic and a therapeutic agent. The purpose of this presentation is to review recent clinical and laboratory studies and advances which are the basis for establishing the pathophysiology of this syndrome and pharmacology of treatment. The FDA has recently approve intravenous Dantrium for treatment of malignant hyperpyrexia. Intravenous and oral Dantrium has much theoretical support and experimental evidence which suggests it will significantly reduce the mortality previously associated with this syndrome.

Selective intubation in the neonatal intensive care unit.

A technique of selective intubation is described for infants who have recurrent or persistent atelectasis. The technique is safe and straightforward.

Croup and epiglottitis: a radiologic study.

Because of the controversy regarding the benefits of the lateral neck and chest radiographs in the evaluation of croup and epiglottitis, a two-part retrospective study was initiated. Part I consisted of a retrospective chart review of 44 patients with a final diagnosis of croup and epiglottitis. Part II consisted of the 42 lateral neck and chest x-rays from patients in part I presented to six radiologists who knew only the patients age and the history of respiratory distress. Two hundred forty-six responses were obtained. The results of the part I study showed that 64% of patients with documented epiglottitis had a positive radiologic diagnosis. Only 33% of patients with croup had a positive radiologic diagnosis and importantly 27% had a diagnosis of possible epiglottitis. The results of part II showed 38% of the documented epiglottitis patients had a positive lateral neck radiograph. The croup patients had a lateral neck and/or chest x-ray positive in 38%. Of interest, 24% had readings consistent with possible epiglottitis. Based on this two-part study, it is our conclusion that the lateral neck and chest x-ray may be unreliable and inaccurate in the diagnosis of croup and epiglottitis. Caution and good clinical judgement should be utilized when interpreting these x-rays.

Single dose amoxicillin treatment of acute otitis media.

A double blind study comparing a single dose of amoxicillin versus a 10-day course of amoxicillin in the treatment of acute otitis media (AOM) was undertaken. All children diagnosed with AOM in a pediatric clinic were requested to participate. After tympanocentesis was performed, patients were randomly assigned to receive either amoxicillin (100 mg/kg) followed by placebo every 8 hours for 10 days or placebo followed by amoxicillin (40 mg/kg/D) for 10 days. Patients returned to clinic on days 3 and 10 post-treatment. Seventeen patients were enrolled: 7 received single dose therapy and 10 received 10 days of therapy. There were no failures in the control group and 3 failures in the single dose group (day 5, day 6, and 11) (p = 0.05). Middle ear isolates included: S. pneumoniae 7, H. influenzae 4, B. catarrhalis 1, and no pathogen in 5. Due to the significant number of failures in the treatment group, the study was prematurely terminated.