Golden ratio and phyllotaxis, a clear mathematical link.

Exploiting Markoff's theory for rational approximations of real numbers, we explicitly link how hard it is to approximate a given number to an idealized notion of growth capacity for plants which we express as a modular invariant function depending on this number. Assuming that our growth capacity is biologically relevant, this allows us to explain in a satisfying mathematical way why the golden ratio occurs in nature.

Development and validation of the FrBio, an international French adaptation of the AzBio sentence lists.

Objectives: The goal of this work was to develop and normalise an international French version of the AzBio sentence test. Design: A corpus of 1000 sentences was generated. These sentences were recorded with four talkers and processed through a four-channel cochlear implant simulation. The mean intelligibility for each sentence achieved by 16 normal-hearing listeners was computed. The consecutively ordered 165 sentences from each talker rendering an average score of 85% were sequentially assigned to 33 lists of 20 sentences. All lists were presented to 30 normal-hearing and 25 hearing-impaired listeners in order to verify their equivalency. Thirty normal-hearing adults were also recruited to assess the test's psychometrics and define norms. Results: The results of the list equivalency validation study showed no significant differences in percent correct scores for 30 sentence lists. A binomial distribution model was used to estimate the 95% critical differences for each potential percentage score. Normalization data showed an average performance between 96% and 99% with a very low standard deviation. Conclusions: With a set of 30 lists, researchers and clinicians can use the FrBio to evaluate a large number of experimental conditions; changes in performance over time or across conditions can then be tracked.

A Retrospective Multicenter Study Comparing Speech Perception Outcomes for Bilateral Implantation and Bimodal Rehabilitation.

OBJECTIVES: To compare speech perception outcomes between bilateral implantation (cochlear implants [CIs]) and bimodal rehabilitation (one CI on one side plus one hearing aid [HA] on the other side) and to explore the clinical factors that may cause asymmetric performances in speech intelligibility between the two ears in case of bilateral implantation. DESIGN: Retrospective data from 2247 patients implanted since 2003 in 15 international centers were collected. Intelligibility scores, measured in quiet and in noise, were converted into percentile ranks to remove differences between centers. The influence of the listening mode among three independent groups, one CI alone (n = 1572), bimodal listening (CI/HA, n = 589), and bilateral CIs (CI/CI, n = 86), was compared in an analysis taking into account the influence of other factors such as duration of profound hearing loss, age, etiology, and duration of CI experience. No within-subject comparison (i.e., monitoring outcome modifications in CI/HA subjects becoming CI/CI) was possible from this dataset. Further analyses were conducted on the CI/CI subgroup to investigate a number of factors, such as implantation side, duration of hearing loss, amount of residual hearing, and use of HAs that may explain asymmetric performances of this subgroup. RESULTS: Intelligibility ranked scores in quiet and in noise were significantly greater with both CI/CI and CI/HA than with a CI-alone group, and improvement with CI/CI (+11% and +16% in quiet and in noise, respectively) was significantly better than with CI/HA (+6% and +9% in quiet and in noise, respectively). From the CI/HA group, only subjects with ranked preoperative aided speech scores >60% performed as well as CI/CI participants. Furthermore, CI/CI subjects displayed significantly lower preoperative aided speech scores on average compared with that displayed by CI/HA subjects. Routine clinical data available from the present database did not explain the asymmetrical results of bilateral implantation. CONCLUSIONS: This retrospective study, based on basic speech audiometry (no lateralization cues), indicates that, on average, a second CI is likely to provide slightly better postoperative speech outcome than an additional HA for people with very low preoperative performance. These results may be taken into consideration to refine surgical indications for CIs.

Factors affecting auditory performance of postlinguistically deaf adults using cochlear implants: an update with 2251 patients.

OBJECTIVE: To update a 15-year-old study of 800 postlinguistically deaf adult patients showing how duration of severe to profound hearing loss, age at cochlear implantation (CI), age at onset of severe to profound hearing loss, etiology and CI experience affected CI outcome. STUDY DESIGN: Retrospective multicenter study. METHODS: Data from 2251 adult patients implanted since 2003 in 15 international centers were collected and speech scores in quiet were converted to percentile ranks to remove differences between centers. RESULTS: The negative effect of long duration of severe to profound hearing loss was less important in the new data than in 1996; the effects of age at CI and age at onset of severe to profound hearing loss were delayed until older ages; etiology had a smaller effect, and the effect of CI experience was greater with a steeper learning curve. Patients with longer durations of severe to profound hearing loss were less likely to improve with CI experience than patients with shorter duration of severe to profound hearing loss. CONCLUSIONS: The factors that were relevant in 1996 were still relevant in 2011, although their relative importance had changed. Relaxed patient selection criteria, improved clinical management of hearing loss, modifications of surgical practice, and improved devices may explain the differences.

Photonic bandgap Bragg fiber sensors for bending/displacement detection.

We demonstrate an amplitude-based bending/displacement sensor that uses a plastic photonic bandgap Bragg fiber with one end coated with a silver layer. The reflection intensity of the Bragg fiber is characterized in response to different displacements (or bending curvatures). We note that the Bragg reflector of the fiber acts as an efficient mode stripper for the wavelengths near the edge of the fiber bandgap, which makes the sensor extremely sensitive to bending or displacements at these wavelengths. Besides, by comparison of the Bragg fiber sensor to a sensor based on a standard multimode fiber with similar outer diameter and length, we find that the Bragg fiber sensor is more sensitive to bending due to the presence of a mode stripper in the form of a multilayer reflector. Experimental results show that the minimum detection limit of the Bragg fiber sensor can be as small as 3 µm for displacement sensing.

HO* radicals induce an unexpected high proportion of tandem base lesions refractory to repair by DNA glycosylases.

Reaction of HO(*) radicals with double-stranded calf thymus DNA produces high levels of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) and, to a minor extent, 8-oxo-7,8-dihydro-2'-deoxyadenosine (8-oxodAdo). Formation of the hydroxylated purine lesions is explained by addition of HO(*) to the C8 position of the purine moiety. It has been reported that tandem lesions containing a formylamine residue neighboring 8-oxodGuo could be produced through addition of a transiently generated pyrimidine peroxyl radical onto the C8 of an adjacent purine base. Formation of such tandem lesions accounted for approximately 10% of the total 8-oxodGuo. In the present work we show that addition of HO(*) onto the C8 of purine accounts for only approximately 5% of the generated 8-oxodGuo. About 50% of the 8-hydroxylated purine lesions, including 8-oxodGuo and 8-oxodAdo, are involved in tandem damage and are produced by peroxyl addition onto the C8 of a vicinal purine base. In addition, the remaining 45% of the 8-oxodGuo are produced by an electron transfer reaction, providing an explanation for the higher yield of formation of 8-oxodGuo compared to 8-oxodAdo. Interestingly, we show that >40% of the 8-oxodGuo involved in tandem lesions is refractory to excision by DNA glycosylases. Altogether our results demonstrate that, subsequently to a single oxidation event, peroxidation reactions significantly increase the yield of formation of hydroxylated purine modifications, generating a high proportion of tandem lesions partly refractory to base excision repair.

Printing in Time for Cranio-Maxillo-Facial Trauma Surgery: Key Parameters to Factor in.

Study Design: retrospective cohort study. Objective: 3D printing is used extensively in cranio-maxillo-facial (CMF) surgery, but difficulties remain for surgeons to implement it in an acute trauma setting because critical information is often omitted from reports. Therefore, we developed an in-house printing pipeline for a variety of cranio-maxillo-facial fractures and characterized each step required to print a model in time for surgery. Methods: All consecutive patients requiring in-house 3D printed models in a level 1 trauma center for acute trauma surgery between March and November 2019 were identified and analyzed. Results: Sixteen patients requiring the printing of 25 in-house models were identified. Virtual Surgical Planning time ranged from 0h 08min to 4h 41min (mean = 1h 46min). The overall printing phase per model (pre-processing, printing, and post-processing) ranged from 2h 54min to 27h 24min (mean = 9h 19min). The overall success rate of prints was 84%. Filament cost was between $0.20 and $5.00 per model (mean = $1.56). Conclusions: This study demonstrates that in-house 3D printing can be done reliably in a relatively short period of time, therefore allowing 3D printing usage for acute facial fracture treatment. When compared to outsourcing, in-house printing shortens the process by avoiding shipping delays and by having a better control over the printing process. For time-critical prints, other time-consuming steps need to be considered, such as virtual planning, pre-processing of 3D files, post-processing of prints, and print failure rate.

In-house 3D Model Printing for Acute Cranio-maxillo-facial Trauma Surgery: Process, Time, and Costs.

Three-dimensional (3D) printing is used extensively in cranio-maxillo-facial (CMF) surgery, but its usage is limited in the setting of acute trauma specifically, as delays in outsourcing are too great. Therefore, we developed an in-house printing solution. The purpose of this study was to describe this process for surgeons treating acute CMF trauma. This series describes the printing process, time required, and printing material costs involved for in-house printing applied to a variety of acute CMF trauma cases involving the upper, middle, and lower thirds of the face and skull. All consecutive patients requiring in-house 3D printed models in a level 1 trauma center for acute trauma surgery in mid-2019 were identified and analyzed. Nine patients requiring the printing of 12 in-house models were identified. The overall printing time per model ranged from 2 hours, 36 minutes to 26 hours, 54 minutes (mean = 7h 55 min). Filament cost was between $0.20 and $2.65 per model (mean = $0.95). This study demonstrates that in-house 3D printing can be done in a relatively short period of time, therefore allowing 3D printing usage for various acute facial fracture treatments. The rapid improvements in the usability of 3D software and printing technology will likely contribute to further adoption of these technologies by CMF-trauma surgeons.

Message transmission efficiency through five telecommunication technologies for signing deaf users.

This cross-sectional research design compares the efficiency of videoconferencing in distance communication for signing deaf persons with that of teletypewriter (TTY)-based telecommunication for the deaf. The efficiency of message transmission was evaluated among 30 signing deaf persons (18 to 65 years) under the six following experimental conditions: (a) Omnitor Allan eC software, (b) Polycom ViaVideo II software, (c) Microsoft Windows Live Messenger software, (d) the D-Link videophone, (e) TTY (written French), and (f) face to face (reference standard). Three timed intelligibility tests and a satisfaction assessment were carried out for each of the experimental conditions. Results showed that videoconferencing technologies offer a better efficacy/time ratio for communication than does TTY. Communication using videoconferencing technologies was very similar to face-to-face communication; this was also true for technologies that are not designed specifically for the deaf population. Equivalent satisfaction levels were observed between TTY and videoconferencing technologies. Microsoft Windows Live Messenger was less preferred due to image fluidity issues.

Contemporary Speech and Oral Language Care for Deaf and Hard-of-Hearing Children Using Hearing Devices.

Contemporary speech and language interventions are not limited to disabilities but embrace the pragmatics of communication behaviors from the perspective of functional social participation. Accordingly, current speech and language therapies for deaf and hard-of-hearing children include a broad spectrum of approaches and techniques. This paper explores contemporary approaches and techniques for speech and oral language interventions for deaf and hard-of-hearing children using hearing devices, evidence of efficacy and how they are implemented in diverse clinical practices.

Speech Perception Changes in the Acoustically Aided, Nonimplanted Ear after Cochlear Implantation: A Multicenter Study.

In recent years there has been an increasing percentage of cochlear implant (CI) users who have usable residual hearing in the contralateral, nonimplanted ear, typically aided by acoustic amplification. This raises the issue of the extent to which the signal presented through the cochlear implant may influence how listeners process information in the acoustically stimulated ear. This multicenter retrospective study examined pre- to postoperative changes in speech perception in the nonimplanted ear, the implanted ear, and both together. Results in the latter two conditions showed the expected increases, but speech perception in the nonimplanted ear showed a modest yet meaningful decrease that could not be completely explained by changes in unaided thresholds, hearing aid malfunction, or several other demographic variables. Decreases in speech perception in the nonimplanted ear were more likely in individuals who had better levels of speech perception in the implanted ear, and in those who had better speech perception in the implanted than in the nonimplanted ear. This raises the possibility that, in some cases, bimodal listeners may rely on the higher quality signal provided by the implant and may disregard or even neglect the input provided by the nonimplanted ear.

Reaching for the other side: generating sequence-dependent interstrand cross-links with 5-bromodeoxyuridine and gamma-rays.

Interstrand cross-links impede critical cellular processes such as transcription and replication and are thus considered to be one of the most toxic types of DNA damage. Although several studies now point to the existence of gamma-radiation-induced cross-links in cellular DNA, little is known about the characteristics required for their creation. Recently, we reported the formation of interstrand cross-links that were specific for mismatched nucleotides within 5-bromo-2'-deoxyuridine-substituted DNA. Given the structural specificity for interstrand cross-link formation, it is likely that open or mismatched regions of DNA in cells may be particularly favorable for cross-link production. Herein, we investigated the effect of the local DNA sequence on the formation of interstrand cross-links, using 5-bromo-2'-deoxyuridine to generate radicals in a mismatched region of DNA. We investigated a total of 12 variations of bases in the mismatched region. The oligonucleotides were irradiated with gamma-rays, and interstrand cross-link formation was analyzed by denaturing gel electrophoresis. We found that the efficiency of cross-link formation was highly dependent on the nature of mismatched bases and, on the basis of electrophoretic mobility, observed several distinctive cross-link structures with specific DNA sequences. This study provides new insights into the reactivity of mismatched DNA and the mechanisms leading to interstrand cross-link formation. The potential application of 5-bromo-2'-deoxyuridine-induced interstrand cross-links to the field of DNA repair is discussed.

Language achievement in children who received cochlear implants between 1 and 2 years of age: group trends and individual patterns.

This study examined receptive and expressive vocabulary and grammar achievement of French-speaking children (n = 27) who received a cochlear implant (CI) between the age of 1 and 2. Standardized measures of language achievement were administered and the language levels attained by children with CIs were compared with that of the normative sample of same-age hearing peers for each measure. As a group, children exhibited language levels within normal limits in all standardized language measures. Examination of individual patterns revealed four different language profiles ranging from normal language levels in all domains to general language delay. Half the participants displayed language levels on par with similar-age peers at the word level; less than half the children obtained average performance at the sentence level. In three of these profiles, comprehension of sentences was impaired. Moreover, the age at implantation was not associated with language achievement. Findings suggest that receiving a CI between the age of 1 and 2 years does not ensure that language abilities will be within normal limits after up to 6 years of experience with the implant.

Effectiveness of Rehabilitation Approaches Proposed to Children With Severe-to-Profound Prelinguistic Deafness on the Development of Auditory, Speech, and Language Skills: A Systematic Review.

Purpose The purpose of this systematic review is to identify and evaluate the available scientific evidence on the effectiveness of rehabilitation approaches proposed to children with severe-to-profound prelinguistic deafness on the hearing, speech, and language skills development. Method Databases (PubMed, CINHAL, PsycInfo, Cochrane, ERIC, and EMBASE) were searched with relevant key words (children, deafness, rehabilitation approach, auditory, speech, and language). Studies published between 2000 and 2017 were included. The methodological quality of the studies was evaluated with the Quality Assessment Tool for Quantitative Studies, and the level of evidence was evaluated with the Oxford Centre for Evidence-Based Medicine Levels of Evidence. Every step of the selection and analysis was made by 2 independent judges. Results Of 1,739 articles listed in different databases, 38 met the inclusion criteria and were selected for analysis. The majority of included articles present a relatively low level of evidence. Rehabilitation approaches that do not include signs appear more frequently associated with a better auditory, speech, and language development, except for receptive language, than approaches that included any form of signs. Conclusion More robust studies are needed to decide on the approach to prioritize with severe-to-profound deaf children.

Intraoperative Surgical Navigation Reduces the Surgical Time Required to Treat Acute Major Facial Fractures.

BACKGROUND: Assessing bone reduction and implant placement in facial fractures is time-consuming because of limited visibility. An intraoperative navigation system allows real-time confirmation of bone positioning and implant placement on the patient's computed tomographic scan. This circumvents the visibility problem and therefore appears to shorten the surgery time. The goal of this study was therefore to determine whether intraoperative navigation reduces the surgical time required to treat patients with acute major facial fractures. METHODS: In this retrospective quasi-experimental study, 50 patients with major facial fractures were identified and randomly assigned to treatment groups. Twenty-two were treated without the use of a navigation system, and 28 were treated using navigation. The Facial frActure Severity Score (FASS) was devised to better assess and control for complexity of cases and control for possible selection bias. RESULTS: The FASS was directly linked to surgery time, whether or not navigation was used. An analysis of covariance demonstrated that the surgical time required to treat major facial fractures, taking into account the FASS, was reduced by 36.1 percent (124.8 minutes) when navigation was used. CONCLUSIONS: This study compared the surgical time required to treat patients with major facial fractures, with and without a navigation system. The use of a navigation system reduced the surgical time by 36.1 percent. This is a significant improvement in reducing the length of craniomaxillofacial procedures. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.

Cochlear reimplantation: causes of failure, outcomes, and audiologic performance.

OBJECTIVES/HYPOTHESIS: To review Quebec's experience with cochlear reimplantation in adults and children and describe failure rates, causes of revision, surgical findings, and the impact of reimplantation on audiologic performances. STUDY DESIGN: Retrospective analysis of all 45 cochlear implant revision surgeries (43 reimplantations) performed on 16 adults and 25 children at the Centre Hospitalier Universitaire de Québec (Hôtel-Dieu de Québec) in Quebec City, between 1987 and 2005. METHODS: : Data on patient demographics, failure sources including review of manufacturer's investigation reports, surgical findings, and outcomes (electrode insertion, complications, and audiologic performances). RESULTS: Mean length of device use before explantation was 5.5 years and ranged from 3 months to 17 years. Explantation was related to documented hard failure (53.3%), traumatic device failure (13.3%, only in children), extrusion of electrode array or scalp flap infection (13.3%), a decrease in performance or soft failure (11.1%), intratemporal pathology (6.7%), and a perilymphatic fistula (2.2%). Overall revision rates of 8.0% and 5.4% were obtained for children and adults, respectively. Total device failure rates of 6.2% in children and 3.3% in adults were calculated. Failure rates decreased with each new generation of Nucleus devices. Perioperative complications were uncommon. A moderate amount of fibrosis was found in the cochlea lumen, and sometimes osteoneogenesis made the reinsertion challenging. Electrode reinsertion depth was mostly comparable with the initial surgery. Speech perception abilities were maintained after reimplantation. CONCLUSIONS: Management of implant failures, including revision surgeries, is becoming an increasingly important part of cochlear implant program activity. It appears more commonly in children because of trauma. Medical and audiologic outcomes are generally excellent. Revision implantation appears to be a safe and effective procedure.

Mechanical loading modulates the differentiation state of vascular smooth muscle cells.

The cause underlying the onset of stenosis after vascular reconstruction is not well understood. In the present study, we evaluated the effect of mechanical unloading on the differentiation state of human vascular smooth muscle cells (hVSMCs) using a tissue-engineered vascular media (TEVM). hVSMCs cultured in a mechanically loaded three-dimensional environment, known as a living tissue sheet, had a higher differentiated state than cells grown on plastic. When the living tissue sheet was detached from its support, the release of the residual stress resulted in a mechanical unloading and cells within the extracellular matrix (ECM) dedifferentiated as shown by downregulation of differentiation markers. The relaxed living tissue sheet can be rolled onto a tubular mandrel to form a TEVM. The rolling procedure resulted in the reintroduction of a mechanical load leading to a cohesive compacted tissue. During this period, cells gradually redifferentiated and aligned circumferentially to the tubular support. Our results suggest that differentiation of hVSMCs can be driven by mechanical loading and may occur simultaneously in the absence of other cell types. The extrapolation of our results to the clinical context suggests the hypothesis that hVSMCs may adopt a proliferative phenotype resulting from the mechanical unloading of explanted blood vessels during vascular reconstruction. Therefore, we propose that this mechanical unloading may play an important role in the onset of vascular graft stenosis.

Electron transfer in DNA duplexes containing 2-methyl-1,4-naphthoquinone.

2-methyl-1,4-naphthoquinone (menadione, MQ) was linked to synthetic oligonucleotides and exposed to near-UV light to generate base radical cations in DNA. This model system of electron transfer induced alkali-labile breaks at GG doublets, similar to anthraquinone and metallointercalators systems. In sharp contrast to other systems, the photolysis of MQ-DNA duplexes gave interstrand cross-links and alkali-labile breaks at bases on the complementary strand opposite the MQ moiety. For sequences with an internal MQ, the formation of cross-links with A and C opposite the MQ moiety was 2- to 3-fold greater than that with G and T. The yield of cross-links was more than 10-fold greater than that of breaks opposite MQ, which in turn was more than 2-fold greater than breaks at GG doublets. The yield of damage at GG doublets greatly increased for a sequence with a terminal MQ. The distribution of base damage was measured by enzymatic digestion and HPLC analysis (dAdo > dThd > dGuo > dCyd). The formation of novel products in MQ-DNA duplexes was attributed to the ability of excited MQ to generate the radical cations of all four DNA bases; thus, this photochemical reaction provides an ideal model system to study the effects of ionizing radiation and one-electron oxidants.