Sums of two biquadrates and elliptic curves of rank ≥4\geq 4

If an integer $n$ is written as a sum of two biquadrates in two different ways, then the elliptic curve $y^2=x^3-nx$ has rank $\geq 3$. If moreover $n$ is odd and the parity conjecture is true, then it has even rank $\geq 4$. Finally, some examples of ranks equal to 4, 5, 6, 7, 8 and 10, are also obtained.Comment: 11 pages, 2 table

A new family of elliptic curves with positive ranks arising from the Heron triangles

The aim of this paper is to introduce a new family of elliptic curves with positive ranks. These elliptic curves have been constructed with certain rational numbers, namely a, b, and c as sides of Heron triangles having rational areas $k$. It turned out that the torsion groups of this family are of the form $\frac{\Bbb{Z}}{2\Bbb{Z}}\times \frac{\Bbb{Z}}{2\Bbb{Z}}$ and also the rank is positive

Speed of light in the extended gravity theories

We shall investigate the possibility of formulation of varying speed of light (VSL) in the framework of Palatini non-linear Ricci scalar and Ricci squared theories. Different speeds of light including the causal structure constant, electromagnetic, and gravitational wave speeds are discussed. We shall see that two local frames are distinguishable and discuss about the velocity of light in these two frames. We shall investigate which one of these local frames is inertial.Comment: 19 pages. to appear in Classical Quantum Gravit

Inflammatory myofibroblastic tumor of the larynx: A case report

Introduction: Inflammatory myofibroblastic pseudotumors are initially described in the lung and various extrapulmonary sites such as the orbits, palatine tonsils, ears, gingiva, pterygomaxillary space, and periodontal tissues. These tumors rarely involve the larynx and predilection to the glottis occurs in an indolent manner. Case Report: This case describes a laryngeal myofibroblastic tumor in a 46-year-old woman who presented with an aggressive tumor that extended to the floor of the mouth and the base of the tongue. Extended supraglottic laryngectomy was undertaken for the patient. The diagnosis was spindle cell proliferation with dense lymphoplasma cell infiltration compatible with inflammatory myofibroblastic tumor (Inflammatory pseudotumor or plasma cell granuloma). Definitive diagnosis was achieved with immunohistochemical (IHC) staining. Conclusion: We believe that further IHC studies are required to define the true nature of these tumors especially for those that behave in an aggressive pattern

MHD thermogravitational convection and thermal radiation of a micropolar nanoliquid in a porous chamber

This work studies the thermogravitational transmission and thermal radiation of micropolar nanoliquid within

The effects of size and type of vocal fold polyp on some acoustic voice parameters

Background: Vocal abuse and misuse would result in vocal fold polyp. Certain features define the extent of vocal folds polyp effects on voice acoustic parameters. The present study aimed to define the effects of polyp size on acoustic voice parameters, and compare these parameters in hemorrhagic and non-hemorrhagic polyps. Methods: In the present retrospective study, 28 individuals with hemorrhagic or non-hemorrhagic polyps of the true vocal folds were recruited to investigate acoustic voice parameters of vowel/ æ/ computed by the Praat software. The data were analyzed using the SPSS software, version 17.0. According to the type and size of polyps, mean acoustic differences and correlations were analyzed by the statistical t test and Pearson correlation test, respectively; with significance level below 0.05. Results: The results indicated that jitter and the harmonics-to-noise ratio had a significant positive and negative correlation with the polyp size (P=0.01), respectively. In addition, both mentioned parameters were significantly different between the two types of the investigated polyps. Conclusion: Both the type and size of polyps have effects on acoustic voice characteristics. In the present study, a novel method to measure polyp size was introduced. Further confirmation of this method as a tool to compare polyp sizes requires additional investigations. © 2018, Shiraz University of Medical Sciences. All rights reserved

The effects of size and type of vocal fold polyp on some acoustic voice parameters

Background: Vocal abuse and misuse would result in vocal fold polyp. Certain features define the extent of vocal folds polyp effects on voice acoustic parameters. The present study aimed to define the effects of polyp size on acoustic voice parameters, and compare these parameters in hemorrhagic and non-hemorrhagic polyps. Methods: In the present retrospective study, 28 individuals with hemorrhagic or non-hemorrhagic polyps of the true vocal folds were recruited to investigate acoustic voice parameters of vowel/ æ/ computed by the Praat software. The data were analyzed using the SPSS software, version 17.0. According to the type and size of polyps, mean acoustic differences and correlations were analyzed by the statistical t test and Pearson correlation test, respectively; with significance level below 0.05. Results: The results indicated that jitter and the harmonics-to-noise ratio had a significant positive and negative correlation with the polyp size (P=0.01), respectively. In addition, both mentioned parameters were significantly different between the two types of the investigated polyps. Conclusion: Both the type and size of polyps have effects on acoustic voice characteristics. In the present study, a novel method to measure polyp size was introduced. Further confirmation of this method as a tool to compare polyp sizes requires additional investigations. © 2018, Shiraz University of Medical Sciences. All rights reserved

Endolaryngeal neurofibroma

Neurofibromatosis is a benign neurogenic tumor, originating from Schwann cells of the nerve sheath. This tumor forms a round, white mass on the course of the involved nerve. It occurs sporadically or in association with von Recklinghausen's disease. Laryngeal involvement is a rare occasion that affects women more than men (F/M ratio 3:2). The most common symptoms are hoarseness, dyspnea and dysphagia. The most common sites of origin are arytenoids and aryepiglottic folds. Because of benign nature of this tumor, conservative surgery is recommended as the management of choice. Only few cases of laryngeal involvement have been reported in literature and this article presents two cases of laryngeal neurofibroma with brief review of literatures. Both cases presented with submucosal, non-ulcerated, endolaryngeal mass with signs and symptoms of airway compromise. In both cases surgical approach was endolaryngeal conservative surgery with CO2 laser. © 2008 Tehran University of Medical Sciences. All rights reserved

Role of the internal superior laryngeal nerve in the motor responses of vocal cords and the related voice acoustic changes

Background: Repeated efforts by researchers to impose voice changes by laryngeal surface electrical stimulation (SES) have come to no avail. This present pre-experimental study employed a novel method for SES application so as to evoke the motor potential of the internal superior laryngeal nerve (ISLN) and create voice changes. Methods: Thirty-two normal individuals (22 females and 10 males) participated in this study. The subjects were selected from the students of Iran University of Medical Sciences in 2014. Two monopolar active electrodes were placed on the thyrohyoid space at the location of the ISLN entrance to the larynx and 1 dispersive electrode was positioned on the back of the neck. A current with special programmed parameters was applied to stimulate the ISLN via the active electrodes and simultaneously the resultant acoustic changes were evaluated. All the means of the acoustic parameters during SES and rest periods were compared using the paired t-test. Results: The findings indicated significant changes (P=0.00) in most of the acoustic parameters during SES presentation compared to them at rest. The mean of fundamental frequency standard deviation (SD F0) at rest was 1.54 (SD=0.55) versus 4.15 (SD=3.00) for the SES period. The other investigated parameters comprised fundamental frequency (F0), minimum F0, jitter, shimmer, harmonic-to-noise ratio (HNR), mean intensity, and minimum intensity. Conclusion: These findings demonstrated significant changes in most of the important acoustic features, suggesting that the stimulation of the ISLN via SES could induce motor changes in the vocal folds. The clinical applicability of the method utilized in the current study in patients with vocal fold paralysis requires further research. © 2016, Shiraz University of Medical Sciences. All rights reserved