The sperm of aging male bustards retards their offspring's development.

Understanding whether the sperm of older males has a diminished capacity to produce successful offspring is a key challenge in evolutionary biology. We investigate this issue using 10 years of reproductive data on captive long-lived houbara bustards (Chlamydotis undulata), where the use of artificial insemination techniques means parents can only influence offspring quality via their gametes. Here we show that paternal aging reduces both the likelihood that eggs hatch and the rate at which chicks grow, with older males producing the lightest offspring after the first month.

Perceptions of dental professionals and laypeople to altered maxillary incisor crowding.

Introduction: The aim of this study was to determine how sensitive dental specialists and laypeople are to maxillary incisor crowding when viewed from the front.

Methods: Computer technology was used to create a series of photographs of the incisors of a smiling woman viewed from the front. The photographs showed varying degrees of maxillary incisor crowding classified according to Little's irregularity index (LII).

Prevalence of tooth agenesis in orthodontic patient population in Western New York.

Permanent tooth agenesis is among the most common developmental anomalies encountered in dental practice. The purpose of this study was to investigate the prevalence and characteristics of tooth agenesis in orthodontic patients in Western New York. Compared to similar studies, it was found that the prevalence of congenitally missing permanent teeth in orthodontic patients is relatively high (11.

Patient experiences with the Forsus Fatigue Resistant Device.

Objective: To investigate patients' experiences with the Forsus Fatigue Resistant Device (FFRD).

Methods: This was a survey focused on patient's comprehensive experience with FFRD, both initially and after several months of wear, including the patient's overall impression of the appliance. The survey was administered to 70 patients wearing FFRD in both university and private practice settings.

Human periodontal ligament cells reaction on a novel hydroxyapatite-collagen scaffold.

Background: Periodontal tissue regeneration presents a highly promising method for restoring periodontal structures. The development of a suitable bioactive scaffold that promotes cell proliferation and differentiation is critical in periodontal tissue engineering. The aim of this study was to evaluate the biocompatibility of a novel 3-dimensional hydroxyapatite-collagen scaffold with human periodontal ligament (hPDL) cell culture.

Tooth bioengineering leads the next generation of dentistry.

Background: As a result of numerous rapid and exciting developments in tissue engineering technology, scientists are able to regenerate a fully functional tooth in animal models, from a bioengineered tooth germ. Advances in technology, together with our understanding of the mechanisms of tooth development and studies dealing with dentally derived stem cells, have led to significant progress in the field of tooth regeneration.

Aim And Design: This review focuses on some of the recent advances in tooth bioengineering technology, the signalling pathways in tooth development, and in dental stem cell biology.

Testes size, testosterone production and reproductive behaviour in a natural mammalian mating system.

1. Testosterone (T) is a key mediator in the expression of numerous morphological and behavioural traits in mammals, but the factors underlying individual variation in circulating T levels are poorly understood. 2.

Sexually extravagant males age more rapidly.

Evolutionary theories of ageing posit that increased reproductive investment occurs at the expense of physiological declines in later life. Males typically invest heavily in costly sexual ornaments and behaviour, but evidence that the expression of these traits can cause senescence is lacking. Long-lived houbara bustards (Chlamydotis undulata) engage in extravagant sexual displays to attract mates and here we show that males investing most in these displays experience a rapid senescent deterioration of spermatogenic function at a younger age.

Does sleep play a role in memory consolidation? A comparative test.

Sleep is a pervasive characteristic of mammalian species, yet its purpose remains obscure. It is often proposed that 'sleep is for the brain', a view that is supported by experimental studies showing that sleep improves cognitive processes such as memory consolidation. Some comparative studies have also reported that mammalian sleep durations are higher among more encephalized species.

Parasite resistance and the adaptive significance of sleep.

Background: Sleep is a biological enigma. Despite occupying much of an animal's life, and having been scrutinized by numerous experimental studies, there is still no consensus on its function. Similarly, no hypothesis has yet explained why species have evolved such marked variation in their sleep requirements (from 3 to 20 hours a day in mammals).

The Phylogeny of Sleep Database: A New Resource for Sleep Scientists.

We have constructed a database that describes the sleeping characteristics of 127 different mammalian species representing 46 families across 17 orders. The data were extracted from 178 separate references that were found using standardized search protocols, and for each study includes information on the time spent in REM and NREM sleep, sleep cycle length, the number of animals sampled, their sex and age, and reference citation. Importantly, we also coded nine laboratory condition scores as a way to control for the procedures that were used to collect the data.

Long-term effectiveness of the continuous and the sectional archwire techniques in leveling the curve of Spee.

Introduction: The correction of a deep overbite with the subsequent achievement of long-term stability is a difficult problem for orthodontists. The role of leveling the curve of Spee (COS) in bite opening and the success of orthodontic treatment has been well documented in the literature. The aim of this study was to investigate whether leveling the COS, by using 2 orthodontic treatment techniques, produces stable results on a long-term basis.

Phylogenetic analysis of the ecology and evolution of mammalian sleep.

The amount of time asleep varies greatly in mammals, from 3 h in the donkey to 20 h in the armadillo. Previous comparative studies have suggested several functional explanations for interspecific variation in both the total time spent asleep and in rapid-eye movement (REM) or "quiet" (non-REM) sleep. In support of specific functional benefits of sleep, these studies reported correlations between time in specific sleep states (NREM or REM) and brain size, metabolic rate, and developmental variables.

Prediction accuracy of computer-assisted surgical visual treatment objectives as compared with conventional visual treatment objectives.

Purpose: This present study used the conventional visualized treatment objectives (VTOs) as a tool to evaluate the predictive value of the Dolphin computer-assisted VTOs.

Materials And Methods: Presurgical cephalometric tracing predictions generated by oral and maxillofacial surgeons and the Dolphin Imaging software were compared with the postsurgical outcome as seen on lateral cephalometric tracings. Sixteen measurements of the predicted and actual postsurgical hard tissue landmarks were compared statistically.

The effects of computer-aided anteroposterior maxillary incisor movement on ratings of facial attractiveness.

Background: Before planning orthodontic treatment, it is necessary to understand societal preferences for facial esthetics. The anteroposterior (AP) position of the maxillary incisors affects the appearance of the soft tissue profile and can be manipulated by orthodontic techniques. To improve the ability to predict the most suitable maxillary incisor position, numerous cephalometric and profilometric measurements have been suggested.

Aspects of mandibular morphology, with specific reference to the antegonial notch and the curve of Spee.

The purpose of this investigation was to determine whether particular metrical traits of the mandibular antegonial notches are associated with specific mandibular growth patterns, and also with the mean depth of the curve of Spee. Thirty pre-treatment lateral cephalometric radiographs belonging to a randomly selected group of patients treated in the orthodontic clinic at the SUNY at Buffalo were digitized. The surface areas of the mandibular antegonial notches, as well as some sagittal facial dimensions were measured on each radiograph.

The morphology of the mandibular antegonial notches and facial symmetry.

Thirty randomly selected pre-treatment postero-anterior cranial radiographs of adolescent patients attending the orthodontic department, School of Dental Medicine, State University of New York at Buffalo comprised the sample in this study. The aims of this study were (1) to compare the depths of the right, and the left, mandibular antegonial notches, and (2) to determine whether the morphology of the antegonial notches bears a statistical relationship to some other transverse metrical characters of the face. The frontal cranial radiographs of thirty patients were digitized to determine the linear, and surface area, measurements of the right, and the left, antegonial notches as well as some transverse dimensions of the faces.

Head posture and deprivation of visual stimuli.

Introduction: Natural head position (NHP) has been defined as the cranial position that is attained when individuals stand with their visual axes in the true horizontal plane. The visual axis is considered to be a key component in establishing, and maintaining NHP so that, in the absence of visual stimuli, gravitation and muscular proprioception chiefly control head position.

Subjects And Methods: In this study, the natural head positions of a group of normal sighted subjects were measured in a well-lighted room.