Visible Cavities Research Articles

Effect of partial substitution of NaCl by KCl on aggregation behavior and gel properties of beef myosin

Based on the three typical gels under KCl substitution groups, the effect of partial substitution of NaCl by KCl (groups: T 1:0.6 M NaCl; T 2: 0.3 M NaCl +0.3 M KCl; T 3: 0.2 M NaCl +0.4 M KCl; T 4:0.6 M KCl) on the aggregation behavior and gel characteristics of myosin was evaluated. The significant changes in hydrophobicity and sulfhydryl content (P < 0.05) indicate KCl substitution enhances myosin aggregation through hydrophobic interactions and disulfide bonds. According to Ca2+-ATP, scanning electron microscopes (SEM) and the rheological results, T2 had a smoother network structure at about 75 °C. Noticeably, T3 had high water holding capacity (WHC), but its gel had some visible cavities. T4 had a gel structure with several irregular aggregates due to a greater aggregation rate. Thus, appropriate partial substitution of NaCl by KCl could enhance beef myosin gel properties and heat-induced aggregation behavior

Caries risk assessment by Caries Management by Risk Assessment (CAMBRA) Protocol among the general population of Pakistan-a multicenter analytical study.

Caries risk (CR) assessment tools are used to properly identify individuals with caries risk and to improve preventive procedures and programs. A tool such as CAMBRA determines the precise protective factors of caries and identifies an individual's specific therapeutic intervention. The purpose of this study was to assess the caries risk using the CAMBRA protocol among the general population of Pakistan. This multicentre analytical study was conducted in ten dental hospitals in different provinces of Pakistan and the caries risk assessment was carried out using a questionnaire that was designed using the Caries Management by Risk Assessment (CAMBRA) protocol. All 521 participants were intra-orally examined to assess oral hygiene status and the presence of disease. Multiple logistic regression test was performed for analysis. A higher number of participants (61.2%) were found to be in the moderate risk category of caries risk assessment. The males are 51% less likely to have caries compared to the females (AOR = 0.49, P = 0.081). The majority of participants (71.3%) had one or more disease indicators, with white spots and visible cavities. Those with visible, heavy plaque were 13.9 times more likely to have caries compared to those without (AOR = 13.92, P < 0.001). Those using calcium and phosphate during the last 6 months were 90% less likely to have caries compared to those not using them (AOR = 0.10, P < 0.001). There was no significant interaction between all eight risk factors retained in the final model (P > 0.05), the Hosmer and Lemeshow Test P < 0.001, classification accuracy = 87.1%, and AUC = 91.2%. The caries risk among the general population of Pakistan is moderate, with significant variation among age groups, education levels, and socioeconomic status.

Interaction of irradiation defects with precipitates in CuCrZr and Cu-1Fe alloys

In this work, we employ transmission electron microscopy and helium ion irradiation to study the interactions between the radiation-induced point defects and the incoherent/semi-coherent precipitates in CuCrZr and Cu-1Fe alloys. Both thin foil and bulk implantation were used to explore the interactions of radiation defects with interfaces. The irradiated defects show a strong interface character dependence in both implanted CuCrZr and Cu-1Fe alloys after similar level of radiation damage. Large-sized voids appear around the incoherent Cr precipitates, while no visible cavities are formed around precipitates in Cu-1Fe alloy. Interestingly, three types of semi-coherent Fe precipitates exhibit various irradiation damage mitigation mechanisms, such as twin boundaries migration, short range elements redistribution and precipitate abnormal growth, which are caused by radiation defect-mediated dislocation glide, element diffusion and mass transportation. The high sink efficiency of the incoherent precipitates trap vacancies and leads to the generation of submicron-sized voids. In contrast, the semi-coherent precipitates can regulate the motion of point defects and effectively enhance the recombination rate of vacancies and interstitials.

PENGARUH SUHU AKTIVASI TERHADAP KUALITAS KARBON AKTIF BIJI DURIAN

&lt;p&gt;This research was conducted to utilize durian seed waste into activated carbon and aims to identify the characteristics of the durian seed activated carbon produced from the activation temperature alteration. With an experimental method with a quantitative approach, the process of making durian seed activated carbon was tested by carbonization using an oven at a temperature of 200 oC for 180 minutes, then temperature activation with alterations of 500, 600, and 700 oC was held for 120 minutes in the furnace, and after it was added with chemical activation by using a 1,5 M H2SO4 solution for 24 hours of immersion. The analysis seen is to test the water content, volatile matter content, ash content, bound carbon content, and to see the surface morphology of activated carbon using SEM (Scanning Electron Microscopy). The results of the test obtained values for water content (6,83 – 12,73%), volatile matter content (16,98 – 26,89%), ash content (7,85 – 12,04%), bound carbon content(61,66 – 75,17%), with an increase in the activation temperature there is a tendency to decrease the value of water content, volatile matter content, ash content, and there is an increase in the value of bound carbon content. And visible cavities on the surface of the activated carbon along with the increase in activation temperature.&lt;/p&gt;

Straightforward synthesis of magnetized activated carbon particles

To develop new sustainable processes, the production of materials with specific physico-chemical properties is highly desirable. Creating hybrid multi-functional materials by combining​ complementary components represents a suitable approach to meet the requirements of various industrial processes. In this work, a straightforward production route to synthesize magnetic (electrode) particles from low cost starting materials is presented. The particles were produced from iron(II) hydroxide and activated carbon (AC) via a microwave-assisted synthesis, creating a magnetite and AC hybrid material (PMAG/AC). SEM imaging shows that the particles are characterized by an amorphous surface structure, typical for AC. Visible cavities are covered by magnetite nanoparticles, confirming the specific surface area measurements, which show a reduction of the surface area when magnetite is added. Cyclic voltammetry shows increasing current densities, ranging from ＋0.49 to ＋1.31 mA cm−2 and from −0.58 to −1.47 mA cm−2 at ＋/−1000 mV vs. Ag/AgCl with increasing immobilized particle mass (25 to 124 mg cm−2). Finally, adsorption experiments were conducted by adding the particles to a culture of electroactive Shewanella oneidensis showing a time-dependent adsorption behavior. These findings represent a promising perspective for future applications of magnetic, conductive and biocompatible particles across a broad range of biotechnological and (bio-)electrochemical processes.

Caries Risk Assessment Using the Caries Management by Risk Assessment (CAMBRA) Protocol among the General Population of Sakaka, Saudi Arabia-A Cross-Sectional Study.

Background: Caries risk assessment is a useful tool in caries prevention and management. Using a tool such as CAMBRA, every individual can be assessed according to his or her disease indicators, risk factors, and protective factors for the current and future caries. Aim: This study aimed to assess caries risk among the general population of Sakaka, Saudi Arabia using the CAMBRA protocol. Methods: This cross-sectional study was conducted at university dental clinics using a questionnaire that was formulated using the CAMBRA caries risk assessment tool; afterwards, all 160 participants were intra-orally examined to assess oral hygiene status and presence of disease. Independent t-tests, ANOVAs, and chi-square tests were performed for analysis. Results: The majority of participants had one or more disease indicators, with white spots and visible cavities (71.3%), and the most commonly present risk factor was visible heavy plaque on teeth (82.5%). The use of fluoridated toothpaste (92.5%) was the most common protective factor. The majority of participants (85%) were in the ‘High’ category of Caries risk assessment. The prevalence of high caries risk was significantly higher among the rural participants compared to the urban (p <0.05), and significantly fewer of those with a primary school education level or lower were in the high dental caries risk group compared to the other educational categories (p <0.001). Conclusion: The caries risk among the general population of Sakaka, Saudi Arabia, is high, with significant variation among age groups, education levels, and geographical locations.

Microstructure and properties analysis of accumulative-roll-bonding-processed Mg–Li/Ta composites for shielding of high-energy electron

The rational combinations of low/high-density metallic materials have been proved to be effective in shielding high-energy electron radiation, however, little has been studied and reported about their synthesis, microstructure, properties and stability against irradiation. In present work, Mg–Li alloy and pure Ta sheets were used to prepare such a novel low/high-density shielding composite by accumulative roll bonding (ARB). Results showed that a uniformed microstructure of composite could be produced after four ARB cycles. Both ARB process and irradiation caused no obvious change in phase compositions of raw materials. In larger areal mass 8.2–12.3 g/cm2, the Mg–Li/Ta composite is a more efficient shield than pure Mg–Li and Ta. Treated by irradiation, a notable number of cavities accompanied by dislocations were formed as main defects in α-Mg phase. The induced dislocations facilitated the nucleation and growth of {1 0–1 2} twins, which in turn acted as sinks of defects. By contrast, Ta phase exhibited good radiation stability as no signs of visible cavities. During ARB process and irradiation, the textures of α-Mg and Ta in composite all varied distinctly. The average micro-hardness of Mg–Li and Ta phase increased with ARB cycles. Treated by irradiation, Mg–Li matrix was sharply hardened while hardness of Ta was slightly decreased. The tensile strength of Mg–Li/Ta composite increased in ARB process and reached the maximum after four cycles. After irradiation, composite exhibited same strength but severe loss of ductility.

ASSESSMENT OF DENTAL CARIOUS LESIONS BY ICDAS II

Introduction. The largest amount of information about the dental caries is provided by the International Caries Detection and Assessment II system (ICDAS II), which is known as evidence-based approach to clinical visual detection of dental caries and enables to detect the stage and depth of carious lesions from the slightest changes in dental enamel to visible cavities affecting dentin. This system has been developed by the group of leading experts in the field of cariology. The results obtained by determining the ICDAS II index contribute to making right clinical decision in the choice of prevention and treatment methods, as well as to predicting the carious progression. The aim of the study is to assess the prevalence and intensity of initial dental caries in people using the ICDAS II index. Materials and methods. A total of 32 patients aged 12 to 25 years were examined. During the dental examination, we assessed the prevalence of dental caries using the ICDAS II. Clinical findings were recorded in oral follow-up charts proposed by the ICDAS Foundation for Epidemiological Studies, which allow us to record dental hard tissue status using six codes: three for assessing carious changes in enamel and three for assessing carious changes in dentine in a sequence of growing severity. Statistical processing of the findings was performed using Student's t-test. Results. Carious lesions were detected in all study participants, their total number was 285, of which 140 (49.1%) had the code 1 and 145 (50.8%) had the code 2 according to the ICDAS II. On average, each of the participants had 9.28 ± 0.67 foci of enamel demineralization. The average number of lesions with codes 1 and 2 by the ICDAS II was respectively 4.54 ± 0.51 and 4.74 ± 0.38 (p&gt; 0.05). The average intensity of dental caries increased with age from 8.29 ± 0.83 in 12-15 year old individuals to 9.39 ± 1.20 in 18-25 year old individuals (p&gt; 0.05), mainly by the growth of the average number of the mean number of caries lesions with the code 1 according to the ICDAS II. Mostly carious lesions are found on the masticatory surfaces, their total number made up 159 (55.7%). 101 (35.4%) caries lesions were found on the vestibular and oral parts of the tooth surfaces, and 25 (8.9%) average lesions were detected on the proximal surfaces. The average intensity of caries detected on the chewing surfaces of the teeth was 5.15 ± 0.49 and was significantly higher than on the vestibular and oral (3.33 ± 0.57, p &lt;0.05) and proximal (0.79 ± 0, 20, p &lt;0.001) surfaces. Conclusion. The obtained results showed a high intensity of carious lesions, with their predominance in the active stages in the two age groups under the study. This proves the appropriateness of using diagnostic ICDAS criteria for early detection of initial caries and its proper treatment.

THE RECOGNITION OF CAVITARY RETINOBLASTOMA TUMORS: Implications for Management and Genetic Analysis.

To assess the role of consolidating adjuvant therapy for cavitary retinoblastoma and to understand if there is any phenotype-genotype correlation. Patients with retinoblastomas having ophthalmoscopically visible cavities between 2004 and 2014 in whom 4 to 6 cycles of systemic chemotherapy were given. Eighteen eyes of 17 patients displayed cavitary retinoblastomas. This represented 6.8% of 250 patients. Mean age at diagnosis was 13 months; 5 unilateral (29%) and 12 bilateral (71%). The mean (median, range) number of retinoblastoma tumors per eye was 2 (2; 1-6). The number of cavities per tumor was 3 (2, 1-6). Intratumoral cavities were seen in the superficial portion of the tumor in 10 eyes (55%). The cavities became visible in eight eyes (44%) and collapsed in eight eyes (44%). Two eyes required enucleation because of relapse in noncavitary tumors. Germline mutations were detected in 14 patients (82%) of whom four demonstrated mosaicism (29%); only one had a low penetrant mutation. The mean follow-up period was 40 (35, 6-120) months. Cavitary retinoblastomas can be detected after systemic chemotherapy with cavities becoming visible after mean two cycles of chemotherapy (secondary cavitary retinoblastoma). The etiology is uncertain. They remain stable and do not require aggressive adjuvant therapy. There was no evident phenotype-genotype correlation with mosaicism noted in 29%.

The ACEII recombinant Trichoderma reesei QM9414 strains with enhanced xylanase production and its applications in production of xylitol from tree barks

BackgroundACEII transcription factor plays a significant role in regulating the expression of cellulase and hemicellulase encoding genes. Apart from ACEII, transcription factors such as XYR1, CRE1, HAP2/3/5 complex and ACEI function in a coordinated pattern for regulating the gene expression of cellulases and hemicellulases. Studies have demonstrated that ACEII gene deletion results in decreased total cellulase and xylanase activities with reduced transcript levels of lignocellulolytic enzymes.ResultsIn this study, we have successfully transformed the ACEII transcription factor encoding gene in Trichoderma reesei to significantly improve its degrading abilities. Transformation experiments on parental strain T. reesei QM9414 has resulted in five genetically engineered strains T/Ace2-2, T/Ace2-5, T/Ace2-8, T/Ace5-4 and T/Ace10-1. Among which, T/Ace2-2 has exhibited significant increase in enzyme activity by twofolds, when compared to parental strain. The T/Ace2-2 was cultured on growth substrates containing 2% bark supplemented with (a) sugar free + MA medium (b) glucose + MA medium and (c) xylose + MA medium. The bark degradation efficiency of genetically modified T/Ace2-2 strain was assessed by analyzing the xylitol production yield using HPAEC. By 6th day, about 10.52 g/l of xylitol was produced through enzymatic conversion of bark (2% bark + MA + xylose) by the T/Ace2-2 strain and by 7th day the conversion rate was found to be 0.21 g/g. Obtained results confirmed that bark growth medium supplemented with d-xylose has profoundly increased the conversion rate of bark by T/Ace2-2 strain when compared to sugar free and glucose supplemented growth media. Results obtained from scanning electron microscopy has endorsed our current results. Bark samples inoculated with T/Ace2-2 strain has showed large number of degraded cells with clearly visible cavities and fractures, by exposing the microfibrillar interwoven complex.ConclusionWe propose a cost effective and ecofriendly method for the degradation of lignocellulosic biomass such as bark to produce xylitol by using genetically modified T. reesei. Efficient conversion rate and production yield obtained in our current study provides a great scope for the xylitol industries, as our method bypasses the pretreatment of bark achieving clean and low-cost xylitol production.

A Comparison of Three Dimensional Ultrasound, Clips and CT for Measuring Interfractional Breast Lumpectomy Cavity Motion

Accurate definition of the lumpectomy cavity (LC) is essential for both partial breast and electron boost planning and delivery. The goal of this study is to evaluate CT, 3DUS and clips in the daily target localization of the LC. Twenty whole breast radiation patients, including 10 with clips, underwent two sets of treatment planning CTs (CT1, CT2) with co-registered 3DUS (US1, US2), separated by approximately 6 weeks. The cavities were independently outlined on each CT and 3DUS dataset. Of the 20 patients, 18 had visible cavities. The shifts in cavity position were calculated from CT, 3DUS and clips. The PTV margins required to be added to the CT1 cavity volume in order to fully encompass the CT2 cavity were calculated without and with shifts according to 3DUS or clips. The median cavity displacement ranged from 0.0-3.0 mm with a maximum of up to 17.9 mm. The cavity displacements were not significantly different when calculated based on 3DUS, CT, or clips (p > 0.05). The average PTV margin required to encompass the CT2 cavity was 6.3 mm without shifts, 4.3 mm with 3DUS shifts and 5.2 mm with clip-based shifts. The differences in the margin between no shift and 3DUS or clip-guided shift were found to be significant, while differences between 3DUS and clip-based shifts were not (p > 0.7). With no shift, the mean CT2 volume that lied outside the CT1 was 3.2 cc compared to 2.4 cc (p 0.9). Without adjusting for the changes in the cavity shape and location, a portion of the volume will be undertreated unless the margins are increased. 3DUS may offer an easily implemented solution to localizing the LC without requiring additional ionizing radiation.

Caries Risk Assessment by CAMBRA in Children Attending a Basic Health Unit

Objective: To determine the caries risk by Caries Management by Risk Assessment (CAMBRA) for children with mixed dentition attending a Basic Health Unit (BHU), identifying the main dental caries disease indicators, risk factors and protective factors. Material and Methods: The sample consisted of 89 children of both genders aged 8-12 years. Clinical and bitewing radiographic examinations were performed by a calibrated examiner, as well as the filling of the adapted CAMBRA form. Dental caries disease indicators, risk factors and protective factors of all subjects were determined. Chi-square test and multivariate logistic regression analysis for all CAMBRA variables were applied (p<0.05). Results: Caries risk was considered high in 38.2% of patients, moderate in 32.6% and low in 29.6%. The most frequent disease indicator was white spot lesion on smooth surfaces (73.0%), the most common risk factor was visible biofilm (78.7%) and protective factor was fluoridated water (100.0%). Children with “moderate risk” and “high risk” had risk of visible cavities or radiographic penetration of the dentin (OR=14.689; OR=574.363, respectively) compared to patients with “low risk”. Conclusion: Caries risk determined as “high” and “moderate” were classifications most observed among children attending BHU. White spot lesions on smooth surfaces were the most frequent dental caries disease indicators and visible plaque on tooth surface and community water fluoridation were the most significant risk factors and protective factors, respectively.

The inception cavitating flows over an axisymmetric body with a blunt head-form

The inception cavitating flows around a blunt body are studied based on flow visualizations and velocity field measureme-nts. The main purpose of the present work is to study the incipient cavity evolution and the interplay between the inception cavitation and the local turbulent flows. A high-speed video camera is used to visualize the cavitating flow structures, and the particle image velocimetry (PIV) technique is used to measure the velocity field, the vorticity, and the Reynolds stresses under non-cavitating and inception cavitating flow conditions. It is found that the appearance of visible cavities is preceded by the formation of a cluster of micro-bubbles not attached to the body surface and in a hairpin-shaped vortex structure. During its evolution, the cavity moves downstream with a lower speed. The effect of the incipient cavity is significant on the local vortical structures but slight on the time- averaged velocity distribution. The mean Reynolds stress distributions in the turbulent shear flow can be substantially altered by the incipient cavities. The presence of the incipient cavities can lead to the production of turbulent fluctuations.

Interactions between Polymorphonuclear Leukocytes and Pseudomonas aeruginosa Biofilms on Silicone Implants In Vivo

Chronic infections with Pseudomonas aeruginosa persist because the bacterium forms biofilms that are tolerant to antibiotic treatment and the host immune response. Scanning electron microscopy and confocal laser scanning microscopy were used to visualize biofilm development in vivo following intraperitoneal inoculation of mice with bacteria growing on hollow silicone tubes, as well as to examine the interaction between these bacteria and the host innate immune response. Wild-type P. aeruginosa developed biofilms within 1 day that trapped and caused visible cavities in polymorphonuclear leukocytes (PMNs). In contrast, the number of cells of a P. aeruginosa rhlA mutant that cannot produce rhamnolipids was significantly reduced on the implants by day 1, and the bacteria were actively phagocytosed by infiltrating PMNs. In addition, we identified extracellular wire-like structures around the bacteria and PMNs, which we found to consist of DNA and other polymers. Here we present a novel method to study a pathogen-host interaction in detail. The data presented provide the first direct, high-resolution visualization of the failure of PMNs to protect against bacterial biofilms.

Energy Estimates and Cavity Interaction for a Critical‐Exponent Cavitation Model

AbstractWe consider the minimization of $\int_{\Omega _\varepsilon } {|D{\bf u}|^p } d{\bf x}$ in a perforated domain $\Omega _\varepsilon : = \Omega \backslash \cup _{i = 1}^M B_\varepsilon ({\bf a}_i )$ of $\font\open=msbm10 at 10pt\def\R{\hbox{\open R}}\R^n$ among maps $\font\open=msbm10 at 10pt\def\R{\hbox{\open R}}{\bf u} \in W^{1,p} (\Omega _\varepsilon ,\R^n )$ that are incompressible (det $D{\bf u} \equiv 1$) and invertible, and satisfy a Dirichlet boundary condition u = g on ∂Ω. If the volume enclosed by g(∂Ω) is greater than |Ω|, any such deformation u is forced to map the small holes Bε(ai) onto macroscopically visible cavities (which do not disappear as ε → 0). We restrict our attention to the critical exponent p = n, where the energy required for cavitation is of the order of $\sum\nolimits_{i = 1}^M {v_i |\log \varepsilon |}$ and the model is suited, therefore, for an asymptotic analysis (v1,…, vM denote the volumes of the cavities). In the spirit of the analysis of vortices in Ginzburg‐Landau theory, we obtain estimates for the “renormalized” energy showing its dependence on the size and the shape of the cavities, on the initial distance between the cavitation points a1,…,aM, and on the distance from these points to the outer boundary ∂Ω. Based on those estimates we conclude, for the case of two cavities, that either the cavities prefer to be spherical in shape and well separated, or to be very close to each other and appear as a single equivalent round cavity. This is in agreement with existing numerical simulations and is reminiscent of the interaction between cavities in the mechanism of ductile fracture by void growth and coalescence. © 2012 Wiley Periodicals, Inc.

The Impact of Manufacturing Technology on the Thermal and Electrical Properties of Ceramic Powders Intended for Spraying Using the APS Method

This article describes the microstructures, chemical and phase compositions, surface morphologies, and internal structures of three ZrO2 x 8Y2O3-type of powders obtained by different manufacturing methods. The first of the analyzed powders was a conventionally prepared form of the material obtained by the spraying method. The second powder was a spherically shaped form of the material obtained from the spray drying process. It displayed a distinctive surface morphology characterized by a rough structure with visible cavities. The particle sizes of these two powders were comparable. The third form of the powder was classified as “nano” and was obtained by a grinding and crushing method. The shapes of individual particles were generally polyhedral with smooth surfaces and no visible porosity. A study of the chemical composition of each form of the powder did not show significant differences, similar to the results obtained from the phase composition study. The results of thermal diffusivity and electrical impedance studies indicated that the electrical and thermal properties of the powders with spherical structures, i.e., sprayed and spray drying, were very similar. The thermal diffusivity and impedance properties of these two powders were greater than those of the ground powder with a finer grain size.

Nanomaterials in preventive dentistry

The prevention of tooth decay and the treatment of lesions and cavities are ongoing challenges in dentistry. In recent years, biomimetic approaches have been used to develop nanomaterials for inclusion in a variety of oral health-care products. Examples include liquids and pastes that contain nano-apatites for biofilm management at the tooth surface, and products that contain nanomaterials for the remineralization of early submicrometre-sized enamel lesions. However, the treatment of larger visible cavities with nanomaterials is still at the research stage. Here, we review progress in the development of nanomaterials for different applications in preventive dentistry and research, including clinical trials.

ERRATUM: “RADIATIVE EFFICIENCY AND CONTENT OF EXTRAGALACTIC RADIO SOURCES: TOWARD A UNIVERSAL SCALING RELATION BETWEEN JET POWER AND RADIO POWER” (2008, ApJ, 686, 859)

We present an analysis of the energetics and particle content of the lobes of 24 radio galaxies at the cores of cooling clusters. The radio lobes in these systems have created visible cavities in the surrounding hot, X-ray-emitting gas, which allow direct measurement of the mechanical jet power of radio sources over six decades of radio luminosity, independently of the radio properties themselves. Using these measurements, we examine the ratio between radio power and total jet power (the radiative efficiency). We find that jet (cavity) power increases with radio synchrotron power approximately as P_jet ~ (L_radio)^beta, where 0.35 < beta < 0.70 depending on the bandpass of measurement and state of the source. However, the scatter about these relations caused by variations in radiative efficiency spans more than four orders of magnitude. After accounting for variations in synchrotron break frequency (age), the scatter is reduced by ~ 50%, yielding the most accurate scaling relation available between the lobe bolometric radio power and the jet (cavity) power. We place limits on the magnetic field strengths and particle content of the radio lobes using a variety of X-ray constraints. We find that the lobe magnetic field strengths vary between a few to several tens of microgauss depending on the age and dynamical state of the lobes. If the cavities are maintained in pressure balance with their surroundings and are supported by internal fields and particles in equipartition, the ratio of energy in electrons to heavy particles (k) must vary widely from approximately unity to 4000, consistent with heavy (hadronic) jets.

Radiative Efficiency and Content of Extragalactic Radio Sources: Toward a Universal Scaling Relation between Jet Power and Radio Power

We present an analysis of the energetics and particle content of the lobes of 24 radio galaxies at the cores of cooling clusters. The radio lobes in these systems have created visible cavities in the surrounding hot, X-ray-emitting gas, which allow direct measurement of the mechanical jet power of radio sources over six decades of radio luminosity, independently of the radio properties themselves. Using these measurements, we examine the ratio between radio power and total jet power (the radiative efficiency). We find that jet (cavity) power increases with radio synchrotron power approximately as P_jet ~ (L_radio)^beta, where 0.35 < beta < 0.70 depending on the bandpass of measurement and state of the source. However, the scatter about these relations caused by variations in radiative efficiency spans more than four orders of magnitude. After accounting for variations in synchrotron break frequency (age), the scatter is reduced by ~ 50%, yielding the most accurate scaling relation available between the lobe bolometric radio power and the jet (cavity) power. We place limits on the magnetic field strengths and particle content of the radio lobes using a variety of X-ray constraints. We find that the lobe magnetic field strengths vary between a few to several tens of microgauss depending on the age and dynamical state of the lobes. If the cavities are maintained in pressure balance with their surroundings and are supported by internal fields and particles in equipartition, the ratio of energy in electrons to heavy particles (k) must vary widely from approximately unity to 4000, consistent with heavy (hadronic) jets.

What factors influence the collapse of trees retained on logged sites?: A case-control study

Living trees (green trees) are intentionally retained on logged sites for many purposes such as wildlife conservation, future wood potential and aesthetics. Minimizing the risk that these trees collapse in the short-term will improve the chances that green-tree retention meets its objectives. In a retrospective case-control study, we identified factors significantly associated with the collapse of living trees retained on logged and slash-burnt sites in south-eastern Australia within 8 years of harvesting. Trees with incomplete crowns or trees with at least one visible cavity were, on average, at three times greater risk of collapse relative to trees with complete crowns or no visible cavities, respectively. Trees with fire-scarring, trees retained greater than 50 m from intact forest or trees retained in isolation were, on average, around twice the risk of collapse relative to trees without fire-scarring, trees retained within 50 m of intact forest or trees retained among other trees, respectively. When considered jointly, the significant factors in a model predicting the collapse of retained trees – tree height, tree diameter, crown form – were all associated with the health of trees. Choosing the healthiest trees possible for fulfilling their function, protecting trees from damage (e.g. fire) and retaining trees near, or among, other trees are likely to reduce the risk of collapse among retained trees and thus contribute to the effectiveness of green-tree retention in logged eucalypt forests.