bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of Lumping Approaches to Predict the Product Yield in a Dual Bed VGO Hydrocracker
Authors: Sadighi Sepehr , Ahmad Arshad , Shirvani Mansoor
Published: March 2012

In this research, to predict the product yields of a pilot scale VGO hydrocracking reactor charged with mono functional hydrotreating and hydrocracking catalysts, two different four-lump models are developed. The first one, called combined bed model, is a simplex in which there is no boundary between hydrotreating and hydrocracking reactions through the reactor. The second one, called dual bed model, is a rigorous model in which hydrogen consumption and hydrotreating reactions are included. In this way, the reactor is subdivided into two different layers, so the effect of hydrotreating reactions on the hydrocracking section can be considered. Results show that the absolute average deviation (AAD%) of the yield prediction for the combined bed and the dual bed models are 8.23 percent and 5.87 percent, respectively. The main reason for the lower average deviation of the dual bed model is its higher accuracy to predict the yield of gas which is also the major advantage of this approach. However, the simplicity of the combined bed model can make it more applicable and attractive, especially when hydrogen consumption as well as sulfur, nitrogen and aromatic specifications of the feed and products are not accessible.
The Investigation of the Selected Parameters of Catalysis on the Effectiveness Factor of MTBE Synthesis in the Case of a Pellet Catalyst
Authors: Fite Carles , Merta Ryszard , Smoszna Anna
Published: March 2012

The influence of selected parameters on the effectiveness factor of catalyst particles for the synthesis reaction of methyl tert-butyl ether (MTBE) from methanol and isobutene is analyzed. The catalyst is the sulfonated ion-exchange resin Bayer K2631. To this aim, the mass and heat balance equations that are presented as a system of differential equations, has been solved by means of the commercial mathematical software MathCad, for which a tailor - made program has been created. Four chosen parameters (tortuosity, particle radius, methanol to isobutene molar ratio and temperature) have been considered to carry out the calculations. The obtained results have been analyzed and presented in a graphical form. They show that the effectiveness factor can be equal, lower or higher than unity depending on the value of the considered parameters. The effectiveness factor is mainly dependent on mass and heat diffusional limitations at certain reaction conditions.
Optimal Taxation of Wealth Transfers When Bequests are Motivated by Joy of Giving
Authors: Brunner Johann K. , Pech Susanne
Published: March 2012

Inherited wealth creates a second distinguishing characteristic of individuals, in addition to earning abilities. We incorporate this fact into a model of optimal labor-income taxation, with bequests motivated by joy of giving. We find that taxes on bequests or on inheritances allow further redistribution if, in the parent generation, initial wealth and earning abilities are positively related. However, these taxes distort the bequest decision and thus, the overall effect on social welfare is ambiguous. On the other hand, a tax on all expenditures of a generation (a uniform tax on consumption plus bequests) has the same redistributive effect as an inheritance tax but does not distort the bequest decision.
Six Steps to a Quick Hazards Assessment at Village Level: A Participatory Assessment Approach Applied in Nawalparasi District, Nepal
Authors: Malakar Yuwan , Bhandari Dinanath
Published: March 2012

The use of participatory approaches in devising disaster risk reduction strategies has increased. With the emergence of this new risk management approach, the concepts of vulnerability assessment and hazards analysis have been put into practice. This paper introduces an efficient, empirically tested, and user‐friendly hazards assessment tool (HAT). HAT follows six steps for a quick hazards assessment. They are i) identification of hazards, ii) historical overview of disasters, iii) severity and frequency analyses, iv) hazard ranking of communities, v) vulnerability scenario building, and vi) summary of hazards analysis. This paper describes each step in a very detailed way demonstrating its application in three village development committees of Nawalparasi District in Nepal. The applicability of HAT is reviewed in terms of promoting learning, fostering local empowerment and building participation, which are the basis of participatory methods of assessment. HAT bears generic criticism of participatory approaches which can be resolved with proper preparation and facilitation. HAT is an attempt to analyze people's perception of vulnerability and suffering from hazards by fostering their active participation in the process that pave the way to holistic disaster risk reduction strategies.
Review of Health Policy and Ethics: A Critical Examination of Values from a Global Perspective
Authors: Stabile Bonnie
Published: March 2012

Health Policy and Ethics makes the case that an examination of health law, health policy and professional standards not only sheds light on the intrinsic values of a society, but more importantly offers insights that will have practical policy implications and lead to improved health practice. Case studies from around the world illustrate central themes.
In the News
Authors: Nicogossian Arnauld
Published: March 2012

In the Editors' opinion, the information summarized for this section has the potential for development of health policies, standards, or for use in the daily practice and counseling of patients in preventative care. For additional information, readers might wish to visit Internet‐based medical news websites, some free of charge, such as PLoS Medicine, MedScape, Stone Heart, Cochrane Collaboration, American College of Physicians, and the World Medical Association.
Demographic Shift and Financial Markets in APEC: New Age Solutions to Age Old Challenges
Authors: Piggott John R. , Sane Renuka
Published: March 2012

The paper reviews the link between demographic shifts and financial products and markets, focusing especially on Asian based APEC economies. It argues that newly developed and emerging APEC economies will need to nurture private sector institutions, which, in partnership with government, can deliver the financial services that the elderly will need. We offer metrics that provide guidance as to whether the required governance and private business competence exist in these economies and suggest measures for improvement. We discuss financial innovation, especially in the arena of products and markets dealing with risks confronted by the elderly, which may provide opportunities for easing the burden of population aging. Finally, we ask what APEC as an organization might be able to achieve through co-operative international agreements.
Asymptotic Behavior of the Finite-Time Ruin Probability with Constant Interest Force and WUOD Heavy-Tailed Claims
Authors: Gao Qingwu , Gu Peng , Jin Na
Published: March 2012

In this paper, we investigate the asymptotic behavior of the finite-time ruin probability in a general risk model with constant interest force, in which the claims are of a widely upper orthant dependence structure, belonging to the intersection of long-tailed class and dominant variation class, and arriving according to an arbitrary counting process. The results we obtained can extend and improve some existing results.
Modified Logistic Model for Mortality Forecasting and the Application of Mortality-Linked Securities
Authors: Hwang Yawen , Huang Hong-Chih
Published: March 2012

This article proposes the modified logistic mortality model as a potential moderation of current models. The fitting and forecasting effects of the proposed modified logistic mortality model are efficient for the mortality data of the United States, Japan, England and Wales, and the modified logistic model provides the best forecasting for persons older than age 30 years under MAPE criterion. In addition, this study considers how to use longevity bonds to manage longevity risk. We apply the proposed modified logistic mortality model to price the bond, and to improve the attractiveness of that bond, we design it to encompass more than one tranche, according to the concept of collateral debt obligation. This design offers investors more choices pertaining to their different risk preferences.
The Plague in Modern Times and the Role of Law
Authors: Chaslot Arthur
Published: March 2012

The aim of this paper is to analyze and understand the role of law with regard to the plague in modern times with an international perspective. The paper will proceed by giving an overview of the different relevant legal regulations, studying the most recent significant cases of the plague, and considering how international law has dealt with them. Finally, this paper will attempt to address if the current international law system would be efficient in addressing the potential of massive plague outbreak and how it would be possible to improve it.
Advanced Optical Technologies: A New Journal for Optical Engineering and Manufacturing
Authors: Pfeffer Michael
Published: March 2012

No abstract available
N-terminal acetylation and other functions of Nα-acetyltransferases
Authors: Hollebeke Jolien , Van Damme Petra , Gevaert Kris
Published: March 2012

Protein N-terminal acetylation by Nα-acetyltransferases (NATs) is an omnipresent protein modification that affects a large number of proteins. The exact biological role of N-terminal acetylation has, however, remained enigmatic for the overall majority of affected proteins, and only for a rather small number of proteins, N-terminal acetylation was linked to various protein features including stability, localization, and interactions. This minireview tries to summarize the recent progress made in understanding the functionality of N-terminal protein acetylation and also focuses on noncanonical functions of the NATs subunits.
A Monte Carlo based analysis of optimal design criteria
Authors: Banks H. T. , Holm Kathleen J. , Kappel Franz
Published: March 2012

Optimal design methods (designed to choose optimal sampling distributions through minimization
of a specific cost function related to the resulting error in parameter estimates) for
inverse or parameter estimation problems are considered. We compare a recent design criteria,
SE-optimal design (standard error optimal design) with the more traditional D-optimal and
E-optimal designs. The optimal sampling distributions from each design are used to compute and
compare standard errors; here the standard errors for parameters are computed using the optimal
mesh along with Monte Carlo simulations as compared to asymptotic theory based standard
errors. We illustrate ideas with two examples: the Verhulst–Pearl logistic population model
and the standard harmonic oscillator model.
Beteiligung des zentralen Nervensystems bei akuten Leukämien und Lymphomen – Indikation und Hinweise zur Durchführung der Diagnostik/Central nervous system involvement in acute leukemia and lymphoma: indications for CNS assessment and advice for diagnostic strategy
Authors: Ringhoffer Mark , Bommer Martin
Published: March 2012

Eine Beteiligung des zentralen Nervensystems (ZNS) bei Leukämien und Lymphomen beeinflusst das therapeutische Konzept. Insbesondere ein Rezidiv in diesem Kompartiment ist mit einer schlechten Prognose vergesellschaftet. Daher sollte der Nachweis einer ZNS-Beteiligung möglichst frühzeitig im Krankheitsverlauf erfolgen. Das Risiko für eine Beteiligung des ZNS variiert erheblich. Bei Erkrankungen mit belegt hohem Risiko für eine ZNS-Beteiligung – wie der akuten lymphoblastischen Leukämie oder dem Burkitt-Lymphom – werden prophylaktische Therapiestrategien angewandt. Obwohl nicht bei allen Entitäten Therapiestandards bei Nachweis von Tumorzellen im Liquor existieren, wird bei positivem Befund meist eine Veränderung der Therapiestrategie mit Einsatz ZNS-gerichteter Maßnahmen (Bestrahlung oder Chemotherapie) resultieren. Dies gilt sowohl für die präemptive Therapiesituation bei asymptomatischen, als auch für die therapeutische Situation bei symptomatischen Patienten. Während parenychmatöse Läsionen mittels Magnetresonanztomographie nachgewiesen werden, wird die Meningeosis neoplastica durch die Untersuchung des Liquors gesichert. Die Liquorzytologie ist in der Hand des erfahrenen Untersuchers bei Leukämien von ausreichender Spezifität, aber begrenzter Sensitivität. Bei Lymphomen ist die alleinige Zytologie von relativ geringer Spezifität, weil eine Abgrenzung zu entzündlichen Pleozytosen gelegentlich sehr schwierig oder gar unmöglich ist. Durch die Kombination von Zytologie und Durchflusszytometrie kann hier sowohl die Sensitivität als auch die Spezifität gesteigert werden. Wichtig ist eine sachgerechte Probengewinnung. Stets sollte die letzte Liquorfraktion der zytologischen und durchflusszytometrischen Evaluierung unterzogen werden, um eine Kontamination aus peripherem Blut zu vermeiden. Eine gute Informationsweitergabe des Klinikers an den Labormediziner ist die Voraussetzung, um ein geeignetes Antikörperpanel für die Diagnostik auswählen zu können. Dies schont die Ressourcen und beschleunigt die Untersuchung. Wegen der häufig geringen zur Verfügung stehenden Zellmenge sollte mit einem Basispanel begonnen werden, das für spezielle Fragestellungen ergänzt wird.
Validation of quantitative analytical procedures in laboratory medicine/Validierung von quantitativen Analysenverfahren in der Laboratoriumsmedizin
Authors: Haeckel Rainer , Sonntag Oswald
Published: March 2012

The validation of analytical procedures in laboratory medicine has been discussed by many authors and several recommendations have been elaborated by working groups and standardization bodies. However, some problems have not sufficiently been solved, for example, permissible limits for the comparability between methods (permissible equivalence), what is the best statistical procedure for estimating the function of the fitting line in scatter plots, and permissible limits for the spread around the fitting line. The present article attempts to summarize the present state-of-the-art and to provide answers to some of the open problems.
Crystal and molecular structure of diorganoammonium oxalatotrimethylstannate, [R2NH2][Me3Sn(C2O4)] (R=i-Bu, cyclohexyl)
Authors: Sow Yaya , Diop Libasse , Molloy Kieran C. , Kociok-Köhn Gabrielle
Published: March 2012

The title compounds [R2NH2][C2O4SnMe3](R=i-Bu, Cy), in which tin atoms adopt a distorted trigonal bipyramidal configuration, have been prepared and submitted to an X-ray diffraction study. These compounds have been obtained from the reaction of (Cy2NH2)2C2O4·H2O or (i-Bu2NH2)2C2O4 with SnMe3Cl. In both [R2NH2][C2O4SnMe3] compounds, the trans complex has an almost regular trigonal bipyramidal geometry around the tin atom. The SnMe3 residues are connected as a chain with bridging oxalate anions in a trans-SnC3O2 framework, the oxygen atoms being in axial positions. The cations connect linear adjacent chains through NH…O hydrogen bonds giving layered structures.
Multidimensional fluorescence microscopy in live cell imaging – A mini review
Authors: Schneckenburger Herbert , Weber Petra , Wagner Michael , Bruns Thomas , Richter Verena , Schickinger Sarah , Wittig Rainer
Published: March 2012

Fluorescence microscopy methods are described with high spatial, spectral, and temporal resolution. In addition to three-dimensional (3D) microscopy, based on confocal, structured, or single-plane illumination, spectral imaging and fluorescence lifetime imaging microscopy are used to probe the conformation of fluorescent molecules as well as their interaction with the microenvironment. In addition to single cells or cell monolayers, 3D cell cultures are used increasingly, as they are more representative for tissue morphology and function. All methods are discussed in the context of controlled light exposure, which is regarded as a key parameter to maintain cell viability. The applications presented in this mini review include autofluorescence measurements of glioblastoma cells as well as various fluorescent markers or fluorescent proteins.
Effect of silica nanoparticle loading and surface modification on the kinetics of RAFT polymerization
Authors: Salami-Kalajahi Mehdi , Haddadi-Asl Vahid , Behboodi-Sadabad Farid , Rahimi-Razin Saeid , Roghani-Mamaqani Hossein
Published: March 2012

S-(thiobenzoyl)thioglycolic acid was used to synthesize poly(methyl methacrylate) via reversible addition-fragmentation chain transfer (RAFT) polymerization. To study the polymerization kinetics, in situ polymerization reactions were performed with different loading of nanoparticles. To investigate the effect of surface modification on the poly­merization kinetics, similar reactions were performed with 3-methacryloxypropyldimethylchlorosilane-modified nanoparticles. Conversion, reaction rate, molecular weight and polydispersity index (PDI) were monitored during poly­merization. According to results, pseudo-first order kinetics is achieved, but the rate constant of chain transfer reaction to the RAFT agent (Ctr) has a very small value. Adding nanoparticles causes no considerable change in the kinetic curves, while there is an optimum value for nanoparticles loading in which the polymerization rate reaches its maximum level. A similar trend is observed for molecular weight; however, increasing silica content results in an increase in PDI values. In comparison with pristine silica nanoparticles, the polymerization rate increases slowly in the case of modified particles. Also, molecular weight and PDI for free and graft chains are studied separately. The molecular weight of free chains increases with increasing nanoparticles loading up to 7 wt% and then decreases, while PDI values increase continually by adding nanoparticles. However, for graft chains, molecular weight and PDI values increase with increasing nanoparticle content.
The Mechanism of Orientation Selectivity in Primary Visual Cortex without a Functional Map
Authors: Hansel David , van Vreeswijk Carl
Published: March 2012

Neurons in primary visual cortex (V1) display substantial orientation selectivity even in species where V1 lacks an orientation map, such as in mice and rats. The mechanism underlying orientation selectivity in V1 with such a salt-and-pepper organization is unknown; it is unclear whether a connectivity that depends on feature similarity is required, or a random connectivity suffices. Here we argue for the latter. We study the response to a drifting grating of a network model of layer 2/3 with random recurrent connectivity and feedforward input from layer 4 neurons with random preferred orientations. We show that even though the total feedforward and total recurrent excitatory and inhibitory inputs all have a very weak orientation selectivity, strong selectivity emerges in the neuronal spike responses if the network operates in the balanced excitation/inhibition regime. This is because in this regime the (large) untuned components in the excitatory and inhibitory contributions approximately cancel. As a result the untuned part of the input into a neuron as well as its modulation with orientation and time all have a size comparable to the neuronal threshold. However, the tuning of the F0 and F1 components of the input are uncorrelated and the high-frequency fluctuations are not tuned. This is reflected in the subthreshold voltage response. Remarkably, due to the nonlinear voltage-firing rate transfer function, the preferred orientation of the F0 and F1 components of the spike response are highly correlated.
Luminance degradation and recovery studies in Alq3 based Organic light emitting diodes
Authors: Rao K. Sudheendra , Samal Girija S. , Mohapatra Y. N.
Published: March 2012

Though organic light emitting diodes are being commercialized in many applications, issues relating to lifetime and degradation remain as fundamental concerns limiting performance. A coherent understanding of degradation mechanisms is yet to emerge. We focus on intrinsic degradation of high quality Alq3 based diodes due to electrical stressing. We monitor progressive luminance degradation and recovery by introducing well defined relaxation time windows in the current stress cycles. The method helps to clearly distinguish between recoverable and permanent degradation systematically. The voltage shift due to degradation and recovery is also monitored as a function of time. Further, we introduce a method of reconstructing the transients of the recoverable part using progressive isolated current pulses as a probe. The recovery of degradation is related to the charging and discharging of the traps in the device and our method provides a technique of measuring significant parameters of trapping through luminance transients. The origin and distinguishing features of the two types of degradation are discussed.
Impact of Metal Contamination of 7.0nm Gate Oxides on Various Substrate Materials
Authors: Saito S. , Hamada K. , Eaglesham D. J. , Shiramizu Y. , Benton J. L. , Kitajima H. , Jacobson S. D. C. , Poate J. M.
Published: March 2012

Metal contamination level will be decreased in order to maintain a device reliability according to device size reduction. Metal contamination from various processes are surveyed. The influence of metal contamination for 7–15nm thick gate oxides is discussed in order to clarify the critical concentration to gate oxides. NIG(Non Intrinsic Gettering) substrates are used in a worst case for gettering. Fe contamination with 4×1010 cm-2 strongly affects the TDDM characteristics, although there is no serious influence in the breakdown voltage even at the concentration of 5×1011 cm-2. The same tendency is observed for Cu contaminant and the critical concentration for TDDB characteristics is around 3×1011 cm-2. High energy B implantation is carried out to form gettering sites near device region. Breakdown voltage and TDDB characteristics are almost the same as epitaxial substrates at Fe concentration up to 1×1012 cm-2. Detailed examination such as SIMS, C-t and DLTS measurements is also supported the effectiveness in high energy gettering.
Speech and Language Therapy Interventions for Children with Cleft Palate: A Systematic Review
Authors: Bessell Alyson , Sell Debbie , Whiting Penny , Roulstone Sue , Albery Liz , Persson Martin , Verhoeven Andrea , Burke Margaret , Ness Andy R.
Published: March 2012

Objective

(1) To examine the evidence for the effectiveness of differences in timing and type of speech and language therapy for children with cleft palate with or without a cleft lip and (2) to identify types of interventions assessed.

Design

Nine databases, including MEDLINE and EMBASE, were searched between inception and March 2011 to identify published articles relating to speech and language therapy for children with cleft palate with or without cleft lip. Studies that included at least 10 participants and reported outcome measures for speech and/or language measures were included. Studies where the experimental group had less than 90% of children with cleft palate with or without cleft lip were excluded. Two reviewers independently completed inclusion assessment, data extraction, and risk of bias assessment for all studies identified.

Results

A total of 17 papers were evaluated: six randomized control trials and 11 observational studies. Studies varied widely on risk of bias, intervention used, and outcome measures reported. None of the studies had a low risk of bias. In terms of intervention approaches, seven studies evaluated linguistic approaches and 10 evaluated motor approaches. Outcomes measures did not support either approach over the other, and based on data reported it was difficult to ascertain which approach is more effective for children with cleft palate with or without cleft lip.

Conclusions

The review found little evidence to support any specific intervention. Key uncertainties need to be identified and adequately powered, methodologically rigorous studies conducted to provide a secure evidence base for speech-language therapy practice in children with cleft palate with or without cleft lip.
Surgical Treatment of Induced Peri‐Implantitis in the Micro Pig: Clinical and Histological Analysis
Authors: Singh Gurbhajan , O'Neal Robert B. , Brennan William A. , Strong Scott L. , Horner Jack A. , Van Dyke Thomas E.
Published: March 2012

The purpose of this pilot study was to determine if lost osseous support adjacent to root form implants could be regenerated using a guided tissue regeneration technique. Three fixtures were placed in each edentulous mandibular bicuspid region of two micro pigs. A total of 6 fixtures were placed in each pig. Due to the presence of a pathologic condition, which was in no way related to the research, the results of one pig were not evaluated. Following osseointegration, peri‐implantitis was induced by the use of ligatures and a soft diet. Three modalities of treatment were performed. Utilizing a surgical flap approach, one third of the fixtures (one per quadrant) were covered with expanded polytetrafluoroethylene (ePTFE) membrane and submerged under the soft tissue complex. The second group of fixtures were submerged under the soft tissue complex with no ePTFE membrane. The control fixtures along with their abutments were debrided and remained non‐submerged. All fixtures were debrided using an air‐abrasive polishing system. The osseous defects around the fixtures were measured from a fixed reference point at the time of surgery and after obtaining block sections. At euthanasia, 12 weeks after surgery, block sections of fixtures were removed, fixed, dehydrated, embedded, sectioned, and prepared for SEM analysis. The clinical results showed a decrease in the depth of osseous defects adjacent to fixtures submerged with a ePTFE membrane. There was a gain of up to 5 mm of bone coronally (mean = 2.13 mm). Histologically, from the base of the defect, 35.6% of the regenerated bone fill was osseointegrated, the remaining 64.4% of the regenerated bone fill had a soft tissue interface between bone and fixture. Fixtures that were submerged without an ePTFE membrane gained up to 3 mm of bone coronally (mean = 1.37 mm) with minimal osseointegration (7.8%). The control specimens exhibited minimal gain in bone height (0.87 mm) with no osseointegration. The data suggest that root form fixtures with peri‐implantitis may be treated with an ePTFE membrane covered by soft tissue. J Periodontol 1993;64:984–989.
Impact of Microbiological Consultation on Clinical Decision Making: A Case‐Control Study of Clinical Management of Recurrent Periodontitis
Authors: Levy D. , Csima A. , Birek P. , Ellen R.P. , McCulloch C.A.G.
Published: March 2012

Data obtained from diagnostic tests may influence the clinician's perception of the patient's state and in some instances may alter subsequent choices of therapeutic interventions. To determine if microbiological consultation influences the clinical management of patients with recurrent periodontitis, an observational, case‐control study was conducted to measure the amount and type of periodontal treatment provided by periodontists (n = 13) who had referred patients with recurrent periodontitis for microbiological consultation. The control group consisted of periodontists (n = 10) who had not referred recurrent periodontitis patients for testing. Patients (n = 31; 20 females, 11 males; mean age 49.8±10.0 years) treated by the case group of periodontists were matched for age and sex to patients (n = 48; 22 females, 26 males; mean age 49.9±8.5 years) treated by the control group of periodontists. Questionnaires were administered to quantitatively assess the amount and type of treatment before and after receiving the microbiological report. Specific analyses were performed as a function of the time of receipt of the microbiology report. Case‐control differences prior to the receipt of the report indicated that the amount of surgery/year was 43% greater for controls (P <0.04), in spite of control patients exhibiting fewer deep pockets than case patients (P <0.05). Case‐control differences after the receipt of the report indicated that case patients were provided with 45% greater number of appointments/year (P < 0.005), 46% greater scaling/year (P <0.02), and 79% greater antibiotics/year (P <0.01) compared with controls. The report influenced 9 (69%) case periodontists to change treatment. Case patients who received a change in treatment (n = 21) exhibited greater number of deep pockets at the time of entry into the study (P <0.05) as compared with case patients who did not receive a change in treatment. Paired Wests of differences within groups before and after the report demonstrated that case patients had a significant increase in treatment after the report as shown by 22% greater number of visits/year (P <0.05) and 54% greater number of antibiotic prescriptions/year (P <0.01). In contrast, controls demonstrated no significant change in treatment. Further, contrasts of change in treatment before and after the report again indicated that case patients exhibited a significantly higher number of visits/year (P <0.04) and number of antibiotic prescriptions/year (P <0.02) compared with control patients. These data indicate that the increased number of visits and antibiotic prescriptions provided by the case periodontists was due, in part, to the impact of the microbiology report on the decision‐making process and in part to the initial pocket depths. J Periodontol 1993; 64:1029‐1039.
Guided Tissue Regeneration With Dentin Biomodification
Authors: Dyer Bret L. , Caffesse Raul G. , Nasjleti Carlos E. , Morrison Edith C.
Published: March 2012

This study was undertaken to provide histologic observations on the effectiveness of citric acid and tetracycline HCl root surface demineralization when used in conjunction with guided tissue regeneration (GTR) procedures. Eight beagle dogs with naturallyoccurring periodontitis were initially treated with scaling and root planing. Four weeks later, 12 mandibular quadrants were treated surgically with modified Widman flap and expanded polytetrafluoroethylene (ePTFE). The teeth in 4 of the quadrants were randomly root conditioned with tetracycline HCl, while those in 4 additional quadrants were randomly treated with citric acid. ePTFE membranes were sutured in place. The beagles received prophylaxis (chlorhexidine and toothbrushing) 3 times a week. After 6 weeks, the membranes were removed; prophylaxes continued for 4 months. Histological evaluation revealed new cementum on the root surfaces. A new periodontal ligament with fibers inserting into the new cementum was noted. Statistical evaluation of the buccolingual measurements demonstrated membranes alone resulted in significantly more new connective tissue and new bone formation than membranes with root conditioning agents. Within the furcation, no significant differences were found. However, there was a trend for more bone formation with membranes alone. Within the limits of this study it may be concluded that GTR utilizing an ePTFE membrane results in new connective tissue attachment and bone regeneration in the beagle dog. Root surface demineralization with citric acid or tetracycline HCl does not enhance the results achieved with GTR when used alone. J Periodontol 1993; 64:1052–1060.
Bone Regeneration Over a Poorly‐Positioned Implant to Correct an Esthetic Deformity: A Case Report
Authors: Fugazzotto Paul A.
Published: March 2012

Guided tissue regeneration was employed to effect regeneration of a disfigured edentulous ridge, with a poorly positioned implant in place. Demineralized freeze dried bone and an expanded polytetrafluoroethylene membrane were utilized and resulted in growth of new, bone‐like material in both a bucco‐lingual and apico‐occlusal dimension, totally submerging the unusable implant. J Periodontol 1993; 64:1088–1091.
1982‐1992: A Decade of Technology Development for Guided Tissue Regeneration
Authors: Scantlebury Todd V.
Published: March 2012

In the last decade guided tissue regeneration (GTR) therapy has evolved in both surgical technique and membrane technology. Given new applications and membrane materials, not only must new surgical techniques be critiqued, but membrane designs must be critically examined as well. A review of historical membrane development suggests that 5 design criteria are essential: 1) tissue integration; 2) cell‐occlusivity; 3) clinical manageability; 4) spacemaking; and 5) biocompatibility. These criteria may be applied to select appropriate materials and designs for specific GTR applications. J Periodontol 1993; 64:1129–1137.
Case Report: Squamous Odontogenic Tumor of the Gingiva
Authors: Saxby Michael S. , Rippin John W. , Sheron Jane E.
Published: March 2012

Gingival swellings are common and most often associated with infection. A case due to the rare peripheral squamous odontogenic tumor is described. It is considered premature to regard peripheral odontogenic tumors as either hamartomatous or neoplastic, and close follow‐up of all such lesions is necessary. J Periodontol 1993;64:1250–1252.
Cryopreserved Cancellous Bone Allograft in Periodontal Intraosseous Defects
Authors: Borghetti Alain , Novakovitch Giséle , Louise Francis , Simeone Didier , Fourel Jean
Published: March 2012

The purpose of this study was to evaluate the potential of cryopreserved cancellous bone allograft (CCBA) in the treatment of intraosseous periodontal defects compared to surgical debridement alone (DEBR). Cancellous bone was procured from femur heads that had been extracted for hip prosthesis procedures and cryopreserved in liquid nitrogen (–196°C) in a tissue bank. Ten patients without systemic disorders and advanced periodontal disease (at least 2 intraosseous defects) participated in this investigation. Measurements from the cemento‐enamel junction were made after initial therapy for clinical attachment level; also gingival recession, probing pocket depth, plaque index, and gingival index and, at the time of surgery, alveolar crest height and osseous defect depth were measured. All measurements were repeated at 1 year‐reentry. Sixteen defects were debrided and grafted (test sites) and 13 defects were debrided only (control sites). Soft tissue measurements showed no statistical differences between the 2 groups. Defect fill was significantly greater with CCBA (1.75 mm) than with DEBR (0.56 mm). Defect depth reduction was 2.06 mm for CCBA and 0.78 mm for DEBR. These values correspond to a percent‐defect resolution of 60% for CCBA and 29% for DEBR. Hard tissue measurements showed significant differences between the 2 groups. CCBA seems to be effective in the short‐term treatment of intraosseous periodontal defects. J Periodontol 1993; 4:128–132.
Clinical Evaluation of the Effect of Tetracycline Root Preparation on Guided Tissue Regeneration in the Treatment of Class II Furcation Defects
Authors: Parashis Andreas O. , Mitsis Fotis J.
Published: March 2012

The purpose of this clinical trial was to evaluate the effect of tetracycline root preparation on guided tissue regeneration in the treatment of Class II furcation defects. Nine pairs of defects with horizontal clinical attachment level value ≥5 mm comprised the study group. Measurements were made to determine presence of plaque, gingival condition, probing depth, and vertical and horizontal clinical attachment level. Defects from each pair were randomly assigned for treatment with an expanded polytetrafluoroethylene membrane (e‐PTFE) and tetracycline root conditioning (100 mg/ml) or the membrane alone. The membranes were removed 4 to 6 weeks postsurgery. Patients were then seen monthly for the duration of the study. Six months postsurgery, all clinical measurements were repeated. Following either treatment, improvement was observed in all clinical parameters, particularly in horizontal clinical attachment level. However, there was not a statistically significant difference in the improvement observed between sites treated with guided tissue regeneration in conjunction with tetracycline as compared to membrane placement alone. Further studies are needed to fully evaluate tetracycline root preparation in conjunction with regenerative therapy. J Periodontol 1993; 64:133–136.
Localized Osteomyelitis Secondary to Endodontic‐Implant Pathosis. A Case Report.
Authors: Sussman Harold I. , Moss Steven S.
Published: March 2012

This case report documents the placement of a single implant fixture in an incisor extraction socket, with the adjacent lateral incisor developing periapical pathosis within 2 weeks. This root‐end inflammatory process proceeded to communicate with the surface of the implant fixture. Although endodontic therapy was performed within one week on the devitalized tooth, an extensive osteomyelitis developed around the implant. Three weeks after placement, the fixture had to be removed. The osteotomy site appeared to be healing uneventfully during the one month follow‐up period. Seven possible causes for this occurrence are discussed. J Periodontol 1993;64:306–310.
Ultrastructure and Histochemistry of the Dental Cuticle in Adult Periodontitis
Authors: Friedman M. T. , Barber P. , Newman H.N.
Published: March 2012

This study examined the dental cuticle (DC) at the interface with cementum surface, as well as its relationship to the overlying subgingival plaque (SP), the so‐called plaque‐free zone (PFZ), the junctional epithelium (JE), and the coronal fibers of the residual periodontal ligament (PL) by transmission electron microscopy (TEM) and histochemistry. Material comprised of 41 extracted, adult periodontitis‐affected teeth (AP). Following extraction, 20 teeth were fixed in 3% glutaraldehyde in 0.1M sodium cacodylate, post‐fixed in 1% osmium tetroxide, embedded in araldite, decalcified in EDTA, re‐embedded in araldite, and sectioned. En bloc histochemistry was undertaken on the remaining 21 teeth, using ruthenium red, alcian blue‐lanthanum nitrate, or safranin‐O, and processed as above. Results show that the DC covered the cementum surface from the SP to the JE, and formed an interface with these structures. No DC was observed at the interface with PL. Morphological variations in DC surface were observed at the interface with the SP and at the so‐called PFZ where bacteria were always in close contact with or surrounded by the DC. At the interface with JE, the DC appeared homogeneous, although layers varying in electron density were distinguishable. Teeth treated histochemically revealed a positive reaction of DC and bacteria to the three methods, suggesting the presence of anionic polymers including glycoproteins in the DC. It was concluded that on adult periodontitis affected teeth, the DC always covers exposed cementum and may mediate bacterial adhesion, and adsorb components from the peridontal pocket. J Periodontol 1993; 64:520–528.
Histologic Observations on the Topography of a Human Periodontal Pocket Viewed in Transverse Step‐Serial Sections
Authors: Krayer Joe W. , Rees Terry D.
Published: March 2012

A histologic overview of a periodontal pocket at the distal of a maxillary first premolar is presented. The material studied is part of the Bernhard Gottlieb collection. This material demonstrated the topography of the periodontal pocket through its complete circumference as seen in transverse step serial sections. From these observations, it is also clear that multiple pockets had formed, each involving a different area of the root surface. The pockets terminated independently and are separated from each other by areas of tissue which progress from pocket epithelium to junctional epithelium to connective tissue attachment. The existence of independent pockets around the root surface of a single tooth points to the problem of access and thus the predictability of nonsurgical therapy as well as concerns that surgical access will necessarily involve areas of unaffected tissues. J Periodontol 1993; 64:585–588.
Inhibitory Effect of Tea Catechins on Collagenase Activity
Authors: Makimura Masaharu , Hirasawa Masatomo , Kobayashi Kihei , Indo Jiro , Sakanaka Senji , Taguchi Takashi , Otake Shigeo
Published: March 2012

A major purpose of this study was to examine inhibitory effect of the catechin derivatives from Japanese green tea Camellia sinensis on collagenase activity. The crude tea catechins, which contain (+)‐catechin (C), (−)‐epicatechin (EC), (+)‐gallocatechin (GC), (−)‐epigallocatechin (EGC), (−)‐epicatechin gallate (ECg), and (−)‐epigallocatechin gallate (EGCg), were tested for their ability to inhibit the prokaryotic and eukaryotic cell derived collagenase activities. Among the tea catechins tested, ECg and EGCg showed the most potent inhibitory effect on collagenase activity when an optimal concentration of tea catechins (100 μg/ml) was added to reaction mixture containing collagenase and collagen. Preincubation of collagenase with tea catechins reduced the collagenase activity as well. In contrast to ECg and EGCg, the other four tea catechins (C, EC, EGC, and GC) did not show any collagenase inhibitory effect. Our results suggest that the steric structure of 3‐galloyl radical is important for the inhibition of collagenase activity. The collagenase activity in the gingival crevicular fluid from highly progressive adult periodontitis was completely inhibited by the addition of tea catechins. These results demonstrated that tea catechins containing galloyl radical possess the ability to inhibit both eukaryotic and prokaryotic cell derived collagenase. J Periodontol 1993; 64:630–636.
Survival Characteristics of Periodontally‐Involved Teeth: A 40‐Year Study
Authors: Chace Richard , Low Samuel B.
Published: March 2012

Four hundred and fifty‐five teeth that were judged clinically to have a questionable prognosis were observed over a 40‐year span in 166 patients in a private practice. Therapy initially was debridement with oral hygiene instruction, followed by flap curettage procedures and preventive maintenance recall therapy. An assessment of compliance based on oral hygiene and recall attendance was also performed. A total of 55 (12%) teeth were lost with an average survival rate of 8.8 years prior to extraction. No teeth were lost during the first 2 years of observation. The majority of extracted teeth were maxillary second molars (38.2%), followed by maxillary first molars (25.5%), and mandibular second molars (16.4%). Tooth loss patterns appeared to be bilaterally symmetrical, with 51% of teeth lost in the right quadrants and 49% lost in the left quadrants. Indications for extraction were primarily periodontal abscesses. Teeth that were considered to have a very questionable prognosis have been retained for many years after therapy, supportive treatment, and patient compliance with recall attendance. J Periodontol 1993;64:701– 705.
The Role of Subgingival Irrigations in the Treatment of Periodontitis
Authors: Shiloah Jacob , Hovious Lee Ann
Published: March 2012

While the efficacy of oral irrigations with antimicrobial agents on the clinical and microbial parameters of gingivitis is well established, the study of the efficacy of intrapocket irrigants on periodontitis has yielded conflicting and inconclusive results regarding both clinical and microbiological parameters. The overall goal of this review paper is to summarize the available information on the efficacy of intrapocket irrigation in the treatment of patients with Periodontitis. The following topics are addressed: 1) the penetrability of the irrigant; 2) pocket irrigation without scaling and root planing; 3) professional pocket irrigation following scaling and root planing; 4) irrigations between recalls; and 5) safety of intrapocket irrigation. Single irrigation of periodontal pockets for short periods of time before or after scaling and root planing has limited effects on periodontal healing. However, continuous irrigation of the periodontal lesion with agents such as povidone iodine during thorough scaling and root planing, such as that carried out under local anesthesia, has promise as an antimicrobial adjunct in periodontal therapy. J Periodontol 1993; 64:835–843.
Periodontal Repair in Dogs: Expanded Polytetrafluoroethylene Barrier Membranes Support Wound Stabilization and Enhance Bone Regeneration
Authors: Haney J. Marc , Nilvéus Rolf E. , McMillan Paul J. , Wikesjö Ulf M.E.
Published: March 2012

A wound stabilizing effect of expanded polytetrafluoroethylene (ePTFE) membranes was evaluated in supraalveolar periodontal defects in 5 beagle dogs. The defects, 5 to 6 mm in height, were surgically created around the 2nd, 3rd, and 4th mandibular premolar teeth in contralateral jaw quadrants. The root surfaces were conditioned with heparin, which, in this model, has been demonstrated to compromise periodontal healing and result in formation of a long junctional epithelium. Wound closure included application of ePTFE membranes around each premolar tooth in one jaw quadrant in each dog and flap positioning coronal to the cemento‐enamel junction in both jaw quadrants. Healing progressed uneventfully except for 3 teeth in 2 dogs, which experienced membrane exposure. The dogs were sacrificed after a 4‐week healing period and tissue blocks were prepared for histometric analysis. Connective tissue repair in heparin + membrane‐treated teeth averaged 98% of the defect height compared to 84% in control heparin‐treated teeth (P ≤ 0.05). Junctional epithelium formation was smaller in membrane‐treated teeth than in control teeth (P ≤0.05) and was usually terminated coronal to the membrane. Bone regeneration was enhanced in membrane‐treated teeth compared to controls (P ≤0.01) and was strongly correlated to the area under the membrane in teeth without membrane exposure (r2 = 0.993; P = 0.002). This correlation was reduced when teeth with membrane exposure were included in the analysis (P ≤0.05). Cementum regeneration was minimal under both treatment conditions. Root resorption was increased in membrane‐treated compared to control teeth (P ≤0.01). This study provides an alternative biologic rationale for membrane‐supported periodontal reconstructive surgery. The results suggest that: 1) connective tissue repair to the root surface is a function of wound stability; 2) bone regeneration is dependent on space provision; 3) exclusion of gingival connective tissue from the root surface does not prevent root resorption; 4) provisions for guided tissue regeneration do not necessarily support cementum regeneration; and 5) complete gingival coverage of the barrier membrane appears critical for optimal healing. J Periodontol 1993; 64:883–890.
R&D infrastructures supported by the Operational Programme Research and Development for Innovation - human resources sustainability
Authors: Marek David , Žížalová Pavla , Valenta Ondřej
Published: March 2012

Infrastruktury pro výzkum a vývoj podpořené z Operačního programu Výzkum a vývoj pro inovace - udržitelnost z hlediska lidských zdrojů

Kvalita výzkumné infrastruktury v Česku byla zatím hodnocena v porovnání s vyspělými "západními" ekonomikami jako spíše podprůměrná. Zároveň je ale zřejmé, že dostupnost špičkové výzkumné infrastruktury je významným faktorem nejen pro kvalitní výzkum, ale i pro mezinárodní spolupráci či spolupráci s aplikačním sektorem. Dosavadní deficit ve sféře výzkumné infrastruktury by měly pomoci řešit současné operační programy a jejich prostřednictvím budovaná nová výzkumná centra. Jaký však bude efekt těchto nových výzkumných infrastruktur, závisí především na schopnostech či možnostech přivést do těchto center kvalitní výzkumné týmy a pracovníky. Příspěvek proto hodnotí z několika hledisek vývoj lidských zdrojů ve výzkumu a vývoji a dílčí trendy dává do souvislosti s indikovanými požadavky vznikajících center. Analýza ukazuje, že v dílčích oborech se může objevit potřeba počtu nových pracovníků, která překračuje nárůst zaměstnanosti odpovídající současným trendům, a tím ohrozit stávající či nová výzkumná centra, potažmo očekávané dopady spojené s jejich výstavbou.