bluuebunny/crossref_metadata_2025 huggingface dataset:
Biomechanical Strength of Human Nasal Septal Lining: Comparison of the Constituent Layers
Authors: Kim David W. , Egan Kristin K. , O'Grady Kevin , Toriumi Dean M.
Published: August 2005

Objective/Hypothesis: Nasal septal perforation is a common complication following surgery involving the nasal septum. Septoplasty, septorhinoplasty, and submucosal resection may result in the inadvertent resection of perichondrium, which may predispose the patient to septal perforations.

Study Design: Controlled human cadaver study testing the biomechanical strength of the constituent layers of nasal septal lining.

Methods: Uniform samples of nasal septal mucosa, perichondrium, and a composite of both layers were obtained from five fresh human cadavers. The mechanical tensile strength of these layers was evaluated and compared with the Instron 4301 Mechanical Testing System (Canton, MA).

Results: Mixed‐effects regression analysis demonstrated a significant difference in the tensile strength of the three groups (mean values ± SD: mucosa, 662 ± 308 g; perichondrium, 1370 ± 798 g; composite, 2340 ± 1252 g). All three pairwise comparisons among the three groups showed a significant difference in tensile strength.

Conclusion: The perichondrial layer imparts the majority of the biomechanical strength to septal lining. Lining flaps containing both perichondrium and mucosa are stronger than flaps with either perichondrium or mucosa alone. Dissection in the subperichondrial plane during septal surgery provides a stronger septal flap and may prevent the development of nasal septal perforation during nasal surgery.
The Degree and Time‐Course Assessment of Radiation‐Induced Trismus Occurring After Radiotherapy for Nasopharyngeal Cancer
Authors: Wang Chon‐Jong , Huang Eng‐Yen , Hsu Hsuan‐Chih , Chen Hui‐Chun , Fang Fu‐Min , Hsiung Ching‐Yeh
Published: August 2005

Objectives/Hypothesis: The objectives were to measure the degree of trismus induced after radiation therapy for nasopharyngeal cancer and assess its progress over time.

Study Design: A prospective, single‐armed measurement study with long‐term follow‐up.

Methods: Seventeen patients with nasopharyngeal cancer treated between 1997 and 1999 were studied. Patients were given radiation therapy with bilateral parallel‐opposing ports of 45 Gy, 25 fractions, then with a reduced volume to 68.4 to 70.2 Gy. The end point was the degree of trismus, which was measured by serial changes of the maximal interincisal distance (MID) at various specified time points before, during, and after radiation therapy.

Results: During the 9 weeks of radiation therapy there was no significant change of MID (normalized MID ranged from 99.8% to 97%). The rate of decrease during this period was 1.3% per month. After radiation therapy there was a rapid decrease of MID between 1 and 9 months (normalized MID values at 1 and 9 mo were 95.5% ± 3.1% and 74.2% ± 5.7%, respectively). The rate of decrease during this period was dramatic (2.4%/mo). One year after radiation therapy, the rate of decrease became slower but was still measurable (0.2%/mo for the period from 12 to 24 mo). For the period from 24 to 48 months. the rate dropped to 0.1% per month. By the end of 48 months, normalized MID was 67.8% ± 7.6%.

Conclusion: By means of measurement over a period of time, it was found that patients with nasopharyngeal cancer had a mean decrease in initial interincisal distance of 32% at 4 years after radiotherapy. The trismus process evolved at different rates. It was rapid at 1 to 9 months after radiation therapy, then became slower and protracted over later years.
Surgical Utility of a New Carbon Dioxide Laser Fiber: Functional and Histological Study
Authors: Devaiah Anand K. , Shapshay Stanley M. , Desai Urman , Shapira Gil , Weisberg Ori , Torres David S. , Wang Zhi
Published: August 2005

Objectives/Hypothesis: The objective was to investigate the functional and histological properties of surgical procedures using a new carbon dioxide (CO2) laser fiber.

Study Design: In vitro and in vivo animal models.

Methods: In vitro experiments using porcine true vocal cord and arytenoid cartilage were designed to study the histological effects of using a photonic band‐gap fiber assembly for CO2 laser energy delivery. Continuous and pulsed‐wave settings at different wattages were tested. In vivo endoscopic surgery on canine larynges and buccal mucosa were performed to examine functional and short‐term healing when performing photonic band‐gap fiber assembly–assisted laser surgery.

Results: In vitro experiments showed consistent cutting with the photonic band‐gap fiber assembly using either straight or 90° bent‐tip fibers. The surrounding tissue in these experiments showed little collateral thermal damage with the average range of thermal width from 14.1 to 18.8 μm in vocal cords and from 5.2 to 10.5 μm in cartilage. Similarly, thermal depth ranged from 28.0 to 350.0 μm in vocal cords and from 269.7 to 739.6 μm in cartilage. In vivo experiments demonstrated ease in maneuvering and flexibility for cutting. There was minimal blood loss, smoke plume, or carbonaceous debris. There were no postprocedural complications. Normal oral intake was noted on postprocedural day 1. There was no evidence of stridor or respiratory distress. Seven days after the procedure, re‐epithelialization was complete in the buccal incisions and nearly completed in the laryngeal incisions.

Conclusion: The photonic band‐gap fiber assembly produced reliable results in cutting with functional characteristics representing an improvement over current technology. The device shows promise as an effective tool for minimally invasive procedures that are amenable to use of the CO2 laser.
Mucosal Biofilm Formation on Middle‐Ear Mucosa in a Nonhuman Primate Model of Chronic Suppurative Otitis Media
Authors: Dohar Joseph E. , Hebda Patricia A. , Veeh Richard , Awad Marie , Costerton J William , Hayes Jay , Ehrlich Garth D.
Published: August 2005

Background: An increased awareness of bacterial biofilms and their formation has led to a better understanding of bacterial infections that occur in the middle ear. Perhaps the best studied pathogen for its propensity toward biofilm formation is Pseudomonas aeruginosa, also the primary pathogen in chronic suppurative otitis media (CSOM).

Objective: The aim of this study was to determine whether P. aeruginosa forms a biofilm in the middle ear in the setting of CSOM in a nonhuman primate model.

Methods: Cynomolgus monkeys underwent perforation of the tympanic membrane and inoculation of the middle ear with a known biofilm‐forming strain of P. aeruginosa. The contralateral ear was used as an internal control and was neither perforated nor infected. At the end of the study period, both ears were irrigated to remove planktonic bacteria, and the middle ear mucosa was removed and examined ultrastructurally using scanning electron microscopy (SEM) for determination of the presence or absence of biofilm formation.

Main Outcome Measure: The identification of middle ear biofilm containing rod‐shaped bacteria.

Results: SEM revealed that P. aeruginosa formed bacterial biofilm in vivo on the middle ear mucosal surface, seen only in the infected ear. Interestingly, biofilm formation caused by cocci was also seen in both the experimental as well as the control ear.

Conclusion:
P. aeruginosa forms biofilms in the middle ear in CSOM in primates. To our knowledge, this is the first report of disease‐associated bacterial biofilm in a nonhuman primate model of CSOM. Such a model lays a foundation for much needed study into the role of biofilms in the pathophysiology of CSOM. Should CSOM be caused by biofilms, which is uncertain at this time, development of novel strategies for treatment and prevention may be possible. The finding of both rods and cocci forming biofilms also warrants further investigation.
Sensitive Pepsin Immunoassay for Detection of Laryngopharyngeal Reflux
Authors: Knight John , Lively Mark O. , Johnston Nikki , Dettmar Peter W. , Koufman Jamie A.
Published: August 2005

Objectives/Hypothesis: To determine whether measurement of pepsin in throat sputum by immunoassay could be used as a sensitive and reliable method for detecting laryngopharyngeal reflux (LPR) compared with 24‐hour double‐probe (esophageal and pharyngeal) pH monitoring.

Study Design: Patients with clinical LPR undergoing pH monitoring provided throat sputum samples during the reflux‐testing period for pepsin measurement using enzyme‐linked immunoadsorbent assay.

Results: Pepsin assay results from 63 throat sputum samples obtained from 23 study subjects were compared with their pH monitoring data. Twenty‐two percent (14/63) of the sputum samples correlated the presence of pepsin with LPR (pH ≤ 4 at the pharyngeal probe), of which the median concentration of pepsin was 0.18 μg/mL (range 0.003–22 μg/mL). Seventy‐eight percent (49/63) of the samples unassociated with (pharyngeal) reflux contained no detectible pepsin. Mean pH values for pepsin‐positive samples were significantly lower than negative samples at both esophageal probe (pH 2.2 vs. pH 5.0) (P < .01) and the pharyngeal probe (pH 4.4 vs. pH 5.8) (P < .01). When the pepsin assay results were compared with the pharyngeal pH data for detecting reflux (events pH ≤ 4), the pepsin immunoassay was 100% sensitive and 89% specific for LPR.

Conclusions: Detection of pepsin in throat sputum by immunoassay appears to provide a sensitive, noninvasive method to detect LPR.
Jugular Foramen Schwannomas: Diagnosis, Management, and Outcomes
Authors: Wilson Matthew A. , Hillman Todd A. , Wiggins Richard H. , Shelton Clough
Published: August 2005

Objectives/Hypothesis: To describe the presentation, radiographic findings, and surgical management of seven patients who have been diagnosed and treated with jugular foramen schwannomas at the University of Utah.

Study Design: Retrospective chart review.

Methods: The charts of seven patients diagnosed with jugular foramen schwannomas were reviewed for presentation symptoms, radiographic findings, and physical examination findings. For the six who underwent surgical excision, the surgical procedure used, cranial nerve function results, audiometric results, perioperative complications, and other follow‐up data are presented.

Results: Seven patients were identified from ages 24 to 69 years. Six of the seven underwent surgical excision. Primary presentation symptoms included dizziness, hearing loss, dysphagia, diplopia, tongue paresis, and hoarseness. The choice of surgical approach was based on the size and location of the tumor. All patients had complete excision of their tumors. The nerve of origin included the glossopharyngeal, vagus, and spinal accessory nerves. Preoperative cranial nerve dysfunction continued postoperatively for lower cranial nerves but resolved in patients who were noted to have preoperative dysfunction of cranial nerve V and VI. The rate of new lower cranial nerve injury was 15% and was only seen in the cranial nerves that were determined to be the nerve of origin. In two cases, a temporary feeding tube was required. No recurrences have been noted to date.

Conclusions: Jugular foramen schwannomas can be successfully diagnosed preoperatively with computed tomography and magnetic resonance imaging. These tumors can be successfully managed with surgery and low morbidity.
Body Fat Composition: A Predictive Factor for Obstructive Sleep Apnea
Authors: Öğretmenoğlu Oğuz , Süslü Ahmet Emre , Yücel Ömer Taşkn , Önerci Tevfik Metin , Şahin Altay
Published: August 2005

Objective: To investigate body fat composition, measured by bioelectrical impedance assay (BIA), for predicting the presence and severity of obstructive sleep apnea‐hypopnea syndrome (OSAHS). Body fat composition was also compared with other well‐known OSAHS predictors such as body mass index (BMI), neck circumference, and abdominal visceral fat.

Study Design: A prospective study was designed. Fifty‐one patients (41 male, 10 female), who were referred to Hacettepe University Faculty of Medicine, Department of Otorhinolaryngology, Head and Neck Surgery with suspected OSAHS, between April 2003 and June 2004, were included in the study.

Methods: All patients underwent polysomnography (PSG) and were classified according to their apnea‐hypopnea index (AHI) into four groups. The cross‐sectional area of abdominal visceral fat was measured by computed tomography (CT) scanning in 33 of the patients. Neck circumference and BMI was measured for all patients. BIA was performed to determine body fat composition. The groups were compared, and correlation of the variables with AHI was investigated.

Results: Of the variables, BMI and percentage of body fat (determined by BIA) were found to be significantly correlated with AHI (r = 0.782, r = 0.647). CT of cross‐sectional area of abdominal visceral fat provided 100% sensitivity and specificity (P < .001) in differentiating simple snorers from OSAHS patients. By combining percentage of body fat and body fat mass, higher levels of sensitivity (95%) and specificity (100%) were achieved for diagnosis of OSAHS.

Conclusion: It was concluded that the BIA could be an inexpensive and practical alternative to prePSG screening tests and should be included in the evaluation of OSAHS patients.
Limited Use of Complementary and Alternative Medicine in Israeli Head and Neck Cancer Patients
Authors: Talmi Yoav P. , Yakirevitch Arkadi , Migirov Lela , Horowitz Zeev , Bedrin Lev , Simon Zvi , Pfeffer M Raphael
Published: August 2005

Hypothesis/Objective: The use of complementary or alternative medicine (CAM) is growing among cancer patients. A Medline search failed to reveal any dedicated report of CAM use specifically in patients with head and neck cancer (HNC).

Study Design: Use of CAM was evaluated in a cohort of treated HNC patients.

Methods: Patients treated for HNC were asked if they had used CAM since their diagnosis. Demographic data and data pertaining to mode of CAM, duration of treatment and effects were obtained.

Results: One hundred forty‐three patients (mean age 61 years) were included. Only nine patients (6.3%) reported using disease related CAM. This included acupuncture (4), Reiki (2), naturopathy (2), hypnosis (1), shiatsu (1), chiropractic treatment (1), homeopathy (1), and selenium (1).

Conclusion: Contrary to the reported use, few of our HNC patients used CAM. Although this could be related to good caregiver‐patient relationship, further studies in comparable populations are warranted to evaluate if this is a local or a pervading finding in head and neck cancer patients.
Shape‐Memory Stapes Prosthesis for Otosclerosis Surgery
Authors: Knox Glenn W. , Reitan Harlan
Published: August 2005

Objectives:The aim of this study was to determine the efficacy of a shape‐memory alloy, Nitinol, as a component of an improved stapes prosthesis.

Study Design:Prospective laboratory and clinical study to develop a Nitinol stapes prosthesis.

Methods:Various diameters of Nitinol wire and temperature transition variants were analyzed with regard to ease of deformation, response to heating, and strength. The size and geometry of the closed hook was determined by measurement of 50 incus cadaver bones. Several heat sources for activating the shape memory were evaluated, including electrocautery, lasers, and warm water. Trial surgeries were then performed on human temporal bones in the laboratory. The closure characteristics of the Nitinol loop were studied. Magnetic resonance imaging (MRI) testing at 1.5 Tesla was performed to determine safety during MRI studies. Preliminary human subject trials were then instituted.

Results:In all cases, a low heat condition was ample to activate the shape memory characteristics of the hook and return it to a closed position after it had been opened. Laser power was generally set well below the power needed for removing bone. The Nitinol loop closed snugly around the incus with application to the top of the hook with a low temperature laser setting. Almost any heat source was effective. MRI testing at 1.5 Tesla showed no movement of the prosthesis. Preliminary results in human subjects showed excellent air‐bone closure. The Nitinol loop holds uniform contact around the incus.

Conclusions:The Nitinol piston greatly simplifies the stapedectomy procedure by taking the need for a hand operated instrument out of the surgeon's hands. Because of the nature of the Nitinol wire, it can never over‐crimp. All these characteristics make the prosthesis advantageous for otosclerosis surgery.
Spawning, copulation and inbreeding coefficients in marine invertebrates
Authors: Addison J.A , Hart M.W
Published: August 2005

Patterns of population genetic variation have frequently been understood as consequences of life history covariates such as dispersal ability and breeding systems (e.g. selfing). For example, marine invertebrates show enormous variation in life history traits that are correlated with the extent of gene flow between populations and the magnitude of differentiation among populations at neutral genetic markers (FST). Here we document an unexpected correlation between marine invertebrate life histories and deviation from Hardy–Weinberg equilibrium (non-zero values ofFIS, the inbreeding coefficient).FISvalues were significantly higher in studies of species with free-spawned planktonic sperm than in studies of species that copulate or have some form of direct sperm transfer to females or benthic egg masses. This result was robust to several different analytical approaches. We note several mechanisms that might contribute to this pattern, and appeal for more studies and ideas that might help to explain our observations.
Bessel-type asymptotic expansions via the Riemann–Hilbert approach
Authors: Wang Z , Wong R
Published: August 2005

A Bessel-type asymptotic expansion is established for the monic polynomials
π

n

(
x
) that are orthogonal with respect to the modified Jacobi weight

,
x
∈(−1,1), where
α
,
β
>−1 and
h
(
x
) is real analytic and strictly positive on [−1,1]. This expansion holds uniformly in a region containing the neighbourhood of the critical value
x
=1. This result complements the two recent results obtained by Kuijlaars and his co-workers, one for
x
bounded away from (−1,1) and the other for
x
in (−1+
δ
,1−
δ
),
δ
>0. Our method is also based on the Riemann–Hilbert approach.
The spectral representation of two-point boundary-value problems for third-order linear evolution partial differential equations
Authors: Pelloni Beatrice
Published: August 2005

We use a spectral transform method to study general boundary-value problems for third-order, linear, evolution partial differential equations with constant coefficients, posed on a finite space domain. We show how this method yields a simple characterization of the discrete spectrum of the associated spatial differential operator, and discuss the obstructions that arise when trying to represent the solution of such a problem as a series of exponential functions.

We first review the theory for second-order two-point boundary-value problems, and present an alternative way to derive the classical series representation, as well as an equivalent integral representation, which generally involves complex contours. We illustrate the advantages of the integral representation by studying in some detail the case where Robin-type boundary conditions are prescribed.

We then consider the third-order case and show that the integral representation is in general
not
equivalent to a discrete series representation, justifying
a posteriori
the failure of some of the classical approaches. We illustrate the third-order case in detail, using the example of the equation
q

t

+
q

xxx

=0 for various types of boundary conditions. In contrast with the second-order case, the qualitative properties of the spectrum of the associated spatial differential operator depend in this case not only on the equation but also on the type of boundary conditions. In particular, the solution appears to admit a series representation only when the prescribed boundary conditions couple the two endpoints of the interval.
The effect of non-Fickian diffusion into surrounding rocks on contaminant transport in a fractured porous aquifer
Authors: Fomin Sergei , Chugunov Vladimir , Hashida Toshiyuki
Published: August 2005

Solute transport in a fractured porous confined aquifer is modelled by using an equation with a fractional-in-time derivative of orderγ, which may vary from 0 to 1. Accounting for non-Fickian diffusion into the surrounding rock mass, which is modelled by a fractional spatial derivative of orderα, leads to the introduction of an additional fractional-in-time derivative of orderα/(1+α) in the equation for solute transport. Closed-form solutions for solute concentrations in the aquifer and surrounding rocks are obtained for an arbitrary time-dependent source of contamination located at the inlet of the aquifer. Based on these solutions, different regimes of contaminant transport in aquifers with various physical properties are modelled and analysed.
Curvature and topology in smectic-A liquid crystals
Authors: Santangelo Christian D , Kamien Randall D
Published: August 2005

Considerations of rotational invariance in one-dimensionally modulated systems such as smectics-A, necessitate nonlinearities in the free energy. The presence of these nonlinearities is critical for determining the layer configurations around defects. We generalize our recent construction for finding exact minima of an approximate nonlinear free energy to the full, rotationally invariant smectic free energy. Our construction exhibits the detailed connection between mean curvature, Gaussian curvature and layer spacing. For layers without Gaussian curvature, we reduce the Euler–Lagrange equation to an equation governing the evolution of a surface. As an example, we determine the layer profile and free energy of an edge dislocation.
Sex as a response to oxidative stress: stress genes co-opted for sex
Authors: Nedelcu Aurora M
Published: August 2005

Despite a great deal of interest, the evolutionary origins and roles of sex remain unclear. Recently, we showed that in the multicellular green alga,
Volvox carteri
, sex is a response to increased levels of reactive oxygen species (ROS), which could be indicative of the ancestral role of sex as an adaptive response to stress-induced ROS. To provide additional support for the suggestion that sex evolved as a response to oxidative stress, this study addresses the hypothesis that genes involved in sexual induction are evolutionarily related to genes associated with various stress responses. In particular, this study investigates the evolutionary history of genes specific to the sexual induction process in
V. carteri
—including those encoding the sexual inducer (SI) and several SI-induced extracellular matrix (ECM) proteins. Surprisingly, (i) a highly diversified multigene family with similarity to the
V. carteri
SI and SI-induced pherophorin family is present in its unicellular relative,
Chlamydomonas reinhardtii
(which lacks both a SI and an ECM) and (ii) at least half of the 12 identified gene members are induced (as inferred from reported expressed sequence tags) under various stress conditions. These findings suggest an evolutionary connection between sex and stress at the gene level, via duplication and/or co-option.
Environmental-induced acquisition of nuptial plumage expression: a role of denaturation of feather carotenoproteins?
Authors: Blanco Guillermo , Frías Oscar , Garrido-Fernández Juan , Hornero-Méndez Dámaso
Published: August 2005

Several avian species show a bright carotenoid-based coloration during spring and following a period of duller coloration during the previous winter, despite carotenoids presumably being fully deposited in feathers during the autumn moult. Carotenoid-based breast feathers of male linnets (
Carduelis cannabina
) increased in hue (redness), saturation and brightness after exposing them to outdoor conditions from winter to spring. This represents the first experimental evidence showing that carotenoid-based plumage coloration may increase towards a colourful expression due to biotic or abiotic environmental factors acting directly on full-grown feathers when carotenoids may be fully functional. Sunlight ultraviolet (UV) irradiation was hypothesized to denature keratin and other proteins that might protect pigments from degradation by this and other environmental factors, suggesting that sunlight UV irradiation is a major factor in the colour increase from winter to spring. Feather proteins and other binding molecules, if existing in the follicles, may be linked to carotenoids since their deposition into feathers to protect colourful features of associated carotenoids during the non-breeding season when its main signalling function may be relaxed. Progress towards uncovering the significance of concealment and subsequent display of colour expression should consider the potential binding and protecting nature of feather proteins associated with carotenoids.
Prioritizing multiple-use landscapes for conservation: methods for large multi-species planning problems
Authors: Moilanen Atte , Franco Aldina M.A , Early Regan I , Fox Richard , Wintle Brendan , Thomas Chris D
Published: August 2005

Across large parts of the world, wildlife has to coexist with human activity in highly modified and fragmented landscapes. Combining concepts from population viability analysis and spatial reserve design, this study develops efficient quantitative methods for identifying conservation core areas at large, even national or continental scales. The proposed methods emphasize long-term population persistence, are applicable to both fragmented and natural landscape structures, and produce a hierarchical zonation of regional conservation priority. The methods are applied to both observational data for threatened butterflies at the scale of Britain and modelled probability of occurrence surfaces for indicator species in part of Australia. In both cases, priority landscapes important for conservation management are identified.
Social learning of floral odours inside the honeybee hive
Authors: Farina Walter M , Grüter Christoph , Díaz Paula C
Published: August 2005

A honeybee hive serves as an information centre in which communication among bees allows the colony to exploit the most profitable resources in a continuously changing environment. The best-studied communication behaviour in this context is the waggle dance performed by returning foragers, which encodes information about the distance and direction to the food source. It has been suggested that another information cue, floral scents transferred within the hive, is also important for recruitment to food sources, as bee recruits are more strongly attracted to odours previously brought back by foragers in both honeybees and bumble-bees. These observations suggested that honeybees learn the odour from successful foragers before leaving the hive. However, this has never been shown directly and the mechanisms and properties of the learning process remain obscure. We tested the learning and memory of recruited bees in the laboratory using the proboscis extension response (PER) paradigm, and show that recruits indeed learn the nectar odours brought back by foragers by associative learning and retrieve this memory in the PER paradigm. The associative nature of this learning reveals that information was gained during mouth-to-mouth contacts among bees (trophallaxis). Results further suggest that the information is transferred to long-term memory. Associative learning of food odours in a social context may help recruits to find a particular food source faster.
Large scale molecular dynamics simulation of native and mutant dihydropteroate synthase–sulphanilamide complexes suggests the molecular basis for dihydropteroate synthase drug resistance
Authors: Giordanetto Fabrizio , Fowler Philip W , Saqi Mansoor , Coveney Peter V
Published: August 2005

Antibiotic resistance is hampering the efficacy of drugs in the treatment of several pathological infections. Dihydropteroate synthase (DHPS) has been targeted by sulphonamide inhibitors for the past 60 years and has developed different amino acid mutations to survive sulpha drug action. We couple homology modelling techniques and massively parallel molecular dynamics simulations to study both the drug-bound and apo forms of native and mutant DHPS. Simulations of the complex between sulphanilamide and
Streptomyces pneumoniae
, DHPS shows how sulphanilamide is able to position itself close to 6-hydroxymethyl-7, 8-dihydropteridine-phosphate in a suitable position for the enzymatic transformation whereas in the mutant complex the sulpha drug is expelled from the catalytic site. Our simulations, therefore, provide insight into the molecular basis for drug resistance with
S. pneumoniae
DHPS.
Possible new definitions of the kilogram
Authors: Davis R.S
Published: August 2005

The kilogram is the unit of mass in the International System. Its definition dates from 1889 and, therefore, predates most of modern physics. The definition simply states that the ‘kilogram’ is the mass of an object known as the international prototype. Thus, we have the extraordinary situation that certain fundamental physical constants (the Planck constant, the Newtonian constant of gravitation, the mass of an electron, the mass of an atom of carbon-12, etc.) are measured in terms of an artefact that was manufactured in the nineteenth century. We begin by describing what is presently known about the long-term stability of artefact standards and how this stability can be experimentally monitored with respect to fundamental constants of physics. Finally, we suggest that present experiments are close to achieving the target uncertainty of the order 10
−8
, although the current incoherence between two classes of experiments is cause for concern.
Population dynamics of harbour seals Phoca vitulina in England: monitoring growth and catastrophic declines
Authors: THOMPSON DAVID , LONERGAN MIKE , DUCK CALLAN
Published: August 2005

Harbour seals Phoca vitulina in eastern England were heavily exploited in the 1960s and 1970s, and affected by phocine distemper virus (PDV) epidemics in 1988 and 2002. Information on their historical and current status is required for their management. To maximize the effectiveness of limited population survey effort we need to both estimate and minimize error.

Presented here are data from annual aerial surveys of the population. Sporadic, synoptic surveys in The Wash, England, were used with more frequent counts of subpopulations in the Moray Firth, Scotland, to determine optimum timing of surveys.

We developed models that explicitly account for variability in both observation and population growth processes to show that the proportion of animals observed is much more variable than the annual growth rates. The latter can therefore be treated as constant within each period, and estimated along with the epidemic mortalities during the study and the precision of the survey results.

The Wash population increased at around 3·1% per annum (pa) [95% confidence interval (CI) 2·1–4·1] between 1973 and 1988. It fell by approximately 52% (95% CI 44–59) as a result of the 1988 PDV epidemic, and subsequently increased at 5·7% pa (95% CI 4·8–6·7). These growth rates were below those reported for European mainland populations, but showed no indication of density‐dependent effects.

The recurrence of PDV in 2002 caused approximately 22% mortality (95% CI 9–33), significantly less than the 1988 epidemic and less than half that in European mainland populations in 2002.

Synthesis and applications. Combining sparse, systematic survey data with sporadic counts produced robust estimates of growth rates and epidemic mortality. The results indicate the value of even limited and sporadic survey effort for monitoring populations. The study has highlighted significant differences in both population dynamics and the severity of disease events between English and European harbour seal populations.
Does infectious disease influence the efficacy of marine protected areas? A theoretical framework
Authors: McCALLUM HAMISH , GERBER LEAH , JANI ANDREA
Published: August 2005

Marine protected areas are increasingly being recommended as an essential component of the management of exploited marine species, but virtually no attention has been given to the influence of parasites. This may be substantial, as a primary effect of marine reserves is to increase the density of an exploited population within the reserve relative to outside the reserve, which may facilitate parasite transmission.

We used a simple deterministic model of microparasitic infection in a fishery with a reserve to investigate equilibrium yield and parasite prevalence inside and outside the reserve as a function of three control variables: the proportion of habitat inside the reserve, fishing mortality and the rate of interchange between the stock and the reserve.

While our model is generic, we parameterized it with values that may be appropriate to the interaction between abalone and Rickettsia.

The presence of a pathogen does not necessarily decrease yield when a reserve is present, particularly if the rate of movement of adult hosts between stock and reserve is low.

Synthesis and applications. Pathogens have important implications for the design of marine reserves. Our modelling identifies two key considerations. First, ‘fishing out’ a pathogen by reducing the host population density to a level below the threshold for disease maintenance is a potential management strategy that is made more difficult by establishing a reserve. Secondly, the effect of a highly transmissible pathogen without a reserve is to cause a rapid decline in equilibrium yield for efforts beyond those that produce maximum sustainable yield, making the fishery prone to collapse. Introducing a reserve decreases yield in this case, but makes the fishery much more resistant to collapse.
Effects of logging on gastrointestinal parasite infections and infection risk in African primates
Authors: GILLESPIE THOMAS R. , CHAPMAN COLIN A. , GREINER ELLIS C.
Published: August 2005

The impact of habitat disturbance on biodiversity conservation and animal health is poorly understood. Selective logging results in a suite of alterations that may increase infection risk and susceptibility to infection in resident populations.

The aim of this study was to improve our understanding of this interplay by examining the effects of logging on infection risk and gastrointestinal parasite infections in three primate species whose populations have responded differently to selective logging in Kibale National Park, Uganda. Populations of redtail guenonsCercopithecus ascaniusare declining in logged forest; red colobusPiliocolobus tephroscelespopulations are in a state of slow recovery; and black‐and‐white colobusColobus guerezapopulations are increasing in logged forest.

We collected faecal samples from these three primate species over a period of 5 years in logged and undisturbed forest, to compare parasite infection prevalence and the magnitude of multiple infections. We also analysed canopy and ground vegetation plots to compare environmental contamination with primate parasites in logged and undisturbed forest.

The prevalence and richness of gastrointestinal helminth and protozoan parasite infections, and the magnitude of multiple infections were greater for redtail guenons in logged than undisturbed forest, but these parameters did not differ between forest types for either colobine. Data from the canopy and ground vegetation plots revealed that infective stages of two representative generalist primate parasites occurred at higher densities in logged compared with undisturbed forest, signifying a greater infection risk for all primate species in logged forest.

Synthesis and applications. This study demonstrates that selective logging can be associated with changes in an important ecological association between hosts and parasites. Our results indicate that anthropogenic habitat change could influence patterns of parasite infection in primates with associated effects on population performance.
Trends in the use of private gardens by wild birds in Great Britain 1995–2002
Authors: CANNON ANDREW R. , CHAMBERLAIN DAN E. , TOMS MIKE P. , HATCHWELL BEN J. , GASTON KEVIN J.
Published: August 2005

Wild birds are commonly observed in private residential gardens in Great Britain. However, little is known about how their use of this significant and increasingly important habitat is changing and how such changes relate to their population status.

Trends in the use of private residential gardens by wild birds in Great Britain were investigated using weekly bird records from 18 300 gardens over 8 years.

We showed that the use of this habitat is seasonal and cyclic, with the timing and regularity of its periodicity variable between species.

We evaluated the significance of the underlying trends in the cyclic reporting rates. Eighteen species showed clear trends, the three with the most negative year term parameter estimates being ‘red‐listed’ as high conservation concern.

Examining correlations with national scale survey data suggested that garden reporting rates are related to general population trends in a number of species, including several of conservation importance. Other species exhibit important differences between national and garden trends.

Synthesis and applications. Our analysis demonstrates ecologically meaningful trends and provides novel insights into seasonal cycles of habitat exploitation, using relatively simple and cost‐effectively collected data. This will lead to greater understanding of the relationships between gardens and general bird populations and of the times of year at which garden habitats are most important for birds. We have demonstrated the practicality and productivity of ‘citizen science’ in this context, and provided new information on the status of some birds of conservation concern.
Plant colonization after managed realignment: the relative importance of diaspore dispersal
Authors: WOLTERS MINEKE , GARBUTT ANGUS , BAKKER JAN P.
Published: August 2005

Deliberate breaching of sea defences is frequently practised with the aim of restoring salt‐marsh vegetation on previously embanked land. However, experience so far has shown that it may take several years before salt‐marsh vegetation is fully established, and it is possible that limited diaspore dispersal plays a role in this. In order to ascertain whether salt‐marsh development may be constrained by limited diaspore dispersal, we studied the dispersal of salt‐marsh species by tidal water.

From October 2001 to the end of March 2002 a total of 38 species, of which 18 were salt‐marsh species, was trapped in a restoration site and adjacent marsh. Aster tripolium, Limonium vulgare, Puccinellia maritima, Salicornia spp., Spergularia media and Suaeda maritima were the most abundant salt‐marsh species, with more than 3 diaspores m−2 trapped during the study period.

For most species, the number of diaspores trapped was representative of their abundance in nearby vegetation. Hence, despite the potential for long‐distance transport by tidal water, our results indicate a predominantly local dispersal of salt‐marsh species.

Synthesis and applications. For the restoration of salt‐marsh vegetation after de‐embankment, relatively rapid colonization may be expected from pioneer and low‐marsh species, provided they are present in a nearby source area and the restoration site is at the appropriate altitude. The establishment of species absent from the adjacent marsh may be dependent on the presence of birds or humans as the main dispersal agents. Breaching of sea defences should preferably take place before or during September, in order to take advantage of the peak in dispersal of salt‐marsh species in the first year after breaching.
The continuing challenges of testing species distribution models
Authors: VAUGHAN I. P. , ORMEROD S. J.
Published: August 2005

Species distribution models could bring manifold benefits across ecology, but require careful testing to prove their reliability and guide users. Shortcomings in testing are often evident, failing to reflect recent methodological developments and changes in the way models are applied. We considered some of the fundamental issues.

Generalizability is a basic requirement for predictive models, describing their capacity to produce accurate predictions with new data, i.e. in real applications beyond model training. Tests of generalizability should be as rigorous as possible: ideally using a large number of independent test sites (≥ 200–300) that represent anticipated applications. Bootstrapping identifies the role of overfitting of the training data in limiting a model's generalizability.

Predictions from most distribution models are continuous variables. Their accuracy may be described by discrimination and calibration components. Discriminatory ability describes how well a model separates occupied from unoccupied sites. It is independent of species prevalence and is readily comparable between models. Rank correlation coefficients, such as the concordance index, are effective measures.

Calibration describes the numerical accuracy of predictions (e.g. whether 40% of sites with predicted probabilities of 0·40 are occupied) but is frequently overlooked in model testing. Poor calibration could mislead any conservation efforts utilizing models to estimate the ‘value’ of different sites for a given species. Effective assessments can be made using smoothed calibration plots.

The effects of species prevalence on nominal presence–absence predictions are well known. The currently preferred accuracy measure, Cohen's κ, has weaknesses. We argue that mutual information measures, based in information theory, may be more appropriate.

Synthesis and applications. Model evaluation must be informative and should ideally: (i) define generalizability in detail; (ii) separate the discrimination and calibration components of accuracy and test both; (iii) adopt assessment techniques that permit more valid intermodel comparisons; (iv) avoid nominal presence–absence evaluation where possible and consider information‐theoretic measures; and (v) utilize the full range of techniques to help diagnose the causes of prediction problems. Few modellers in applied ecology and conservation biology satisfy these needs, making it difficult for others to evaluate models and identify potential misuses. The problems are real, and if uncorrected will damage conservation efforts through the inaccurate assessment of distribution and habitat preferences of important organisms.
Optimizing dispersal study design by Monte Carlo simulation
Authors: SKARPAAS OLAV , SHEA KATRIONA , BULLOCK JAMES M.
Published: August 2005

The distribution of dispersal distances (the dispersal kernel) is a major determinant of spatial population dynamics, yet little is known about the shape of the dispersal kernel for most species. This is partly because of the relative difficulty of measuring dispersal, exacerbated by a lack of standardized protocols. We suggest that this problem can be addressed by using modelling approaches to aid the design of studies to quantify dispersal.

In this study we present such an approach by optimizing seed trap sampling design using stochastic simulations. A number of alternative sampling designs (random placements, grid arrays, transects, sectors and annuli arrangements) for a point source were tested against a common kernel to assess the best methods for estimating the dispersal kernel.

For a given source strength and total trap area, transects and sectors of traps usually provided better data for kernel estimation than random placement, grid arrays and annuli. Kernel estimation was improved by increasing the source strength (the number of dispersing propagules) and the trap area, as expected.

When the ‘true’ kernel was unknown, transects were slightly better for identifying the thin‐tailed exponential distribution, whereas sectors were better for detecting the fat‐tailed half‐Cauchy.

In the case of anisotropic dispersal (here, dispersal biased in one direction), annuli and grid arrays performed better than transects and sectors when the anisotropy was unknown. However, when the anisotropy was anticipated, and the trap arrangements were adjusted accordingly, transects and sectors were better. This was true regardless of source strength and total trap area.

Synthesis and applications. This study presents a simulation approach to the design of dispersal experiments. While the general results of our simulations can be used by those designing field studies for plant point sources, the simulation approach itself can be modified for a wide range of organisms, dispersal mechanisms and dispersal measurement approaches. Thus, the approach presented here facilitates improvements of dispersal study designs, which in turn will increase the precision of dispersal kernel estimates and predictions of spatial population dynamics, including modelling of rates of spread or metapopulations. This is invaluable in a range of ecological applications, such as the management of rare or invasive species, predicting species’ response to climate change, or planning species reintroductions.
Integrating published data and citizen science to describe bird diversity across a landscape
Authors: LEPCZYK CHRISTOPHER A.
Published: August 2005

Knowledge of species diversity across a landscape is essential for answering ecological questions and developing conservation and management goals and protocols. However, data on species occurrence are often limited, with the consequence that species lists are incomplete.

As a means to develop a complete species occurrence list for an urbanizing landscape in south‐eastern Michigan, USA, all bird species accounts from four public and private organizations were integrated, and all officially documented rare birds added. A citizen science approach was then used to develop an independent species list from c. 1700 landowner surveys.

The specific goals of the research were to: (i) develop a complete list of species occurrence across a landscape; (ii) ascertain what percentage of the total species pool landowners could collectively identify; (iii) identify species that had not been noted in the census data sets but could be corroborated; (iv) compare the percentage overlap among different bird censuses; and (v) assess the potential value of casual (i.e. citizen science) records to bird distribution studies.

The resulting list comprised 318 individual bird species, which was 8·5% greater than any of the individual lists. Landowners identified 171 bird species (c. 54%) and had > 50% overlap with all existing databases. In addition, landowners identified 10 species noted only in a single database of rare or vagrant species. The percentage overlap of species across the five different lists ranged from 35% to 66%, with the differences stemming largely from different protocols. Subsetting the data for one county within the landscape reduced the unique species to 294, which was approximately equivalent to the existing county species list.

Synthesis and applications. The findings highlight the value of surveying private landowners as a means of detecting species presence/absence in numerous inaccessible locations, and the important role landowners can play in providing species occurrence information. Similarly, the results indicate the need to use multiple data sources for establishing a list of potential species occurrence for the conservation and management of biological resources.