Time-saving Alternatives Research Articles

Assessment of the accuracy of biparametric MRI/TRUS fusion-guided biopsy for index tumor evaluation using postoperative pathology specimens

BackgroundMultiparametric MRI (mpMRI) is widely used for the diagnosis, surveillance, and staging of prostate cancer. However, it has several limitations, including higher costs, longer examination times, and the use of gadolinium-based contrast agents. This study aimed to investigate the accuracy of preoperatively assessed index tumors (ITs) using biparametric MRI (bpMRI)/transrectal ultrasound (TRUS) fusion biopsy compared with radical prostatectomy (RP) specimens.MethodsWe included 113 patients diagnosed with prostate cancer through bpMRI/TRUS fusion-guided biopsies of lesions with a Prostate Imaging Reporting and Data System (PI-RADS) category ≥ 3. These patients underwent robot-assisted laparoscopic radical prostatectomy (RARP) at our institution between July 2017 and March 2023. We examined the localization of preoperative and postoperative ITs, the highest Gleason score (GS), and tumor diameter in these patients.ResultsThe preoperative cT stage matched the postoperative pT stage in 53 cases (47%), while 31 cases (27%) were upstaged, and 29 cases (26%) were downstaged (Weighted Kappa = 0.21). The preoperative and postoperative IT localizations were consistent in 97 cases (86%). The concordance rate between Gleason groups in targeted biopsies and RP specimens was 51%, with an upgrade in 25 cases (23%) and a downgrade in 27 cases (25%) (Weighted Kappa = 0.42). The maximum diameter of the IT and the maximum cancer core length on biopsy were correlated with the RP tumor's maximum diameter (p < 0.001 for both).ConclusionThe diagnostic accuracy of bpMRI/TRUS fusion biopsy is comparable to mpMRI, suggesting that it can be a cost-effective and time-saving alternative.

Manufacturing Process of Helicopter Tail Rotor Blades from Composite Materials Using 3D-Printed Moulds

Conventional processes require a mould for the manufacture of each test product, which often results in high costs but is ideal for large series of products. In contrast, for prototypes, additive manufacturing processes are a suitable low-cost time-saving alternative. The primary objective of this study is to investigate the capabilities of 3D-printed tooling in a real-life scenario for composite blades with low production numbers and prototypes in order to allow development and production costs to decrease and to also reduce lead times in the early phases of new projects. The 3D printing process is economically advantageous in terms of production costs for the composite blade mould, reducing the cost three times compared to the conventional manufacturing process. To obtain the composite helicopter blade, the following phases were carried out: the starting design of the mould, 3D printing and assembly of the mould sections, and blade manufacturing. The economic analysis of the two mould manufacturing methods shows an approximately equal ratio between the manufacturing costs of the 3D-printed mould and the manufacturing costs of the blade, whereas in the conventional processes, the costs for mould manufacturing represent 75% of the total cost and the rest (25%) of the cost is spent on blade manufacturing.

Inverse Identification of Drucker–Prager Cap Model for Ti-6Al-4V Powder Compaction Considering the Shear Stress State

Numerical simulation is an important method to investigate powder-compacting processes. The Drucker–Prager cap constitutive model is often utilized in the numerical simulation of powder compaction. The model contains a number of parameters and it requires a series of mechanical experiments to determine the parameters. The inverse identification methods are time-saving alternatives, but most procedures use a flat punch during the powder-compacting process. It does not reflect the densification behavior under a shearing stress state. Here, an inverse identification approach for the Drucker–Prager cap model parameters is developed by using a hemispherical punch for the powder-compacting experiment. The error between the numerical and experimental displacement–load curves was minimized to identify the Drucker–Prager cap model of titanium alloy powder. The identified model was then verified by powder-compacting experiments with the flat punch. The displacement–load curves acquired by numerical simulation were compared to the displacement–load curves obtained through experiments. The two curves are found to be in good agreement. Meanwhile, the relative density distribution of the powders is similar to the experimental results.

Accuracy and Precision of Mandible Segmentation and Its Clinical Implications: Virtual Reality, Desktop Screen and Artificial Intelligence

Objective3D modeling is a major challenge in computer-assisted surgery (CAS). Manual segmentation, as the gold standard, is tedious, time consuming, and particularly challenging for the mandible, while artificial intelligence (AI)-based segmentation is a promising and time-saving alternative. However, little is known about the clinical implications of various segmentation methods. MethodIn this cross-over study, ten mandibles were segmented in virtual reality (VR), on a desktop screen (DS) by five experts and via five AI models. The exported mandible models were evaluated using metrics, a public reference (PUBDS), and blinded assessments by two radiologists. ResultsAverage segmentation-to-volume accuracy (1 = poor, 5 = perfect) was comparable for human segmentation (VR: 4.56; DS: 4.33; PUBDS: 4.55) and significant better than AI-based segmentation (AI: 3.80), while the average segmentation-to-segmentation accuracy revealed that DS (91.4 %/0.37 mm [Dice coefficient/average Hausdorff distance]) was more comparable to PUBDS than to VR (90.1 %/0.44 mm). The precision of VR (96.8 %/0.14 mm) and DS (96.6 %/0.15 mm) was superior to PUBDS (94.1 %/0.21 mm) and the AI method (89.2 %/0.60 mm). While VR was significantly faster than DS and PUBDS for the manual segmentation methods (p = 0.007/< 0.001), in contrast, the AI method is not time sensitive due to its possible hardware scalability. ConclusionAccuracy and precision of mandible segmentation depends primarily on CT quality and anatomical site, which should be considered in clinical applications and the generation of AI training data and could negatively impact CAS. Although current AI models have perfect intra-model reliability, they demonstrate higher inter-model variability and are accompanied by invalid outliers making human review still necessary. In summary, the use of VR in manual segmentation showed high accuracy and precision overall while saving time, making it the preferred method over DS due to its good usability.

Initial Outcomes of Freehand Transperineal Biopsies Regarding Diagnostic Value and Safety: An Early Experience at King Fahad Specialist Hospital, Buraydah, Saudi Arabia.

Prostate cancer is a common type of cancer in Saudi Arabia with a high incidence rate. Trans-rectal ultrasound guided prostatic biopsy (TRUSBx) has been the standard diagnostic study for prostate cancer since a landmark study in 1989which showed that it is better than digitally directed biopsy sampling of the prostate. As an alternative to TRUSBx, transperineal biopsies (TPBx) have gained popularity as they give a higher accuracy rate and avoid many complications. A new study has been conducted in Riyadh, Saudi Arabia to compare TRUSBx and TPBx showed that TPBx has a significantly higher detection rate of prostate cancer cases compared to TRUSBx (45.1% vs. 29.1%, p=0.003). The aim of this study is to determine the diagnostic value and safety of freehand transperineal prostate biopsy in patients with an elevated prostatic specific antigen (PSA) and/or abnormal digital rectal exam in King Fahad Specialist Hospital KFSH in Buraydah, Qassim region, Saudi Arabia. This is an observational retrospective study of all patients (n=39) who underwent transperineal biopsies at KFSH to assess the diagnostic value and safety of the procedure. The mean age of the patients was 70.3 (SD 10.1) years. The most commonly found diagnosis was adenocarcinoma (61.5%), and incidence of complications was detected in (5.1%) of the patients. We concluded that the freehand technique TPBx has a high accuracy rate in detecting prostatic cancer. However, the learning curve could be a limiting factor in implementing it. Increasing the number of biopsies could positively affect diagnostic accuracy, especially with our low complication rate in this procedure. A low number of biopsies in the older age group can give an accurate result with a low risk of complications. Although template-guided TPBx and robot-guided TPBx are better options, the freehand technique represents a cost-effective and time-saving alternative. However, more studies are needed to compare the outcome of such a technique.

Modified zirconia-bonded M-bridge for prosthetic rehabilitation of missing anterior tooth in a young adolescent

A space in the maxillary anterior region of the dental arch can produce a huge psychological impact on the young patient due to the unesthetic appearance of the teeth, necessitating immediate care for esthetic and functional rehabilitation. Trauma due to avulsion accounts for 0.5%–16% of all traumatic dental injuries to permanent dentition. Despite the availability of a variety of therapeutic treatments, including implants and removable partial dentures, these solutions have several drawbacks. Challenges range from poor wear compliance, growth disruption when used on young patients, and the inability to endure strong masticatory stresses. For the replacement of a missing tooth, resin-bonded bridges offer a minimally invasive, practical, cost-effective, and time-saving alternative. Maryland bridge is a type of resin-bonded bridge, the simplest, and most popular due to its micromechanical retention property. However, its disadvantages include esthetically unappealing and dislodgment of the prosthesis. Therefore, modifications may be introduced in the design of the bridge to address these limitations. The present case report illustrates a clinical case of prosthetic rehabilitation in a young patient utilizing modified zirconia-bonded M-bridge in conjunction with additional structural changes and can be considered as highly reliable early rehabilitation.

Visualization of Mitochondria During Embryogenesis in Zebrafish by Aggregation-Induced Emission Molecules.

Aggregation-induced emission (AIE) molecules have been widely utilized for fluorescence imaging in many biomedical applications, benefited from large Stokes shift, high quantum yield, good biocompatibility, and resistance to photobleaching. And visualization of mitochondria is almost investigated in vitro and ex vivo, but in vivo study of mitochondria is more essential for systematic biological research, especially during embryogenesis. Therefore, suitable and time-saving alternatives with simple operation based on AIE molecules are urgently needed compared with traditional transgenic approach. Five tetraphenylethylene isoquinolinium (TPE-IQ)-based molecules with AIE characteristics and their ability of mitochondrial visualization in vitro and in vivo and mitochondrial tracking during embryogenesis on zebrafish model were investigated. The biosafety of these AIE molecules was also evaluated systematically in vitro and in vivo. All these five AIE molecules could image mitochondria in vitro with good biocompatibility. In them, TPE-IQ1 exhibited excellent imaging quality for in vivo visualization and tracking of mitochondria during the 4-day embryogenesis in zebrafish, in comparison with the conventional transgenic fluorescent protein. Furthermore, TPE-IQ1 could visualize mitochondrial damage induced by chemicals in real time on 24-h post fertilization (hpf) embryos. This study indicated TPE-IQ-based AIE molecules had the potential for mitochondrial imaging and tracking during embryogenesis and mitochondrial damage visualization in vivo.

Fast Hollow Fiber Liquid-Phase Microextraction as a Greener Alternative for the Determination of N,N-Dimethyltryptamine and Harmala Alkaloids in Human Urine.

Ayahuasca tea is an entheogen hallucinogenic beverage used for shamanic and spiritual purposes, prepared by the decoction of different Amazonian plants containing N,N-dimethyltryptamine (DMT) and harmala alkaloids. Since the therapeutic potential of this tea has been broadly studied in recent years, mainly for the treatment of psychiatric disorders, the determination of the ayahuasca tea components in human and animal matrices is of utmost importance. In order to avoid the use of large amounts of toxic solvents, typically employed in traditional sample preparation methods, hollow fiber liquid-phase microextraction (HF-LPME) presents a greener and time-saving alternative. The present study aims to fully develop and apply an HF-LPME method for the determination of DMT, harmine (HRM), harmaline (HRL), and tetrahydroharmine (THH) in human urine samples using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Fractional factorial and Box–Behnken designs were used to identify and optimize significant method variables. Once optimized, validation has shown a limit of detection (LoD) of 1.0 ng/ml for DMT and 2.0 ng/ml for the harmala alkaloid. The limit of quantification (LoQ) was of 5.0 ng/ml for all analytes. The method has shown to be linear over a concentration range of 5–200 ng/ml (r2 ≥ 0.99). Intra/inter-day precision and accuracy met the acceptance criteria at the three quality control (QC) levels studied (15.0, 90.0, and 170.0 ng/ml, n = 6, each). Matrix effect evaluation showed predominant ion enhancement and recovery values were above 80%. Dilution factors of 10- and 20-fold have shown acceptable values of accuracy. Selectivity studies showed no interferences. Analysis of eight authentic samples collected from four subjects proved method feasibility. A simple, time-saving and green alternative for the analysis of DMT and harmala alkaloids in human urine samples was developed, optimized using design of experiments, fully validated and applied to authentic samples.

Evaluation of Effectiveness of Self-Adhesive Composites for Amalgam Repair with or Without Alloy Primer, in Terms of Shear Bond Strength

Purpose: The purpose of the present research was to evaluate the effectiveness of self-adhesive composites in amalgam repair as time-saving alternatives to universal bonding-universal composite materials, with or without the usage of Alloy Primer in terms of shear bond strength. Materials and Methods: Forty-two disc-shaped amalgam samples were prepared by condensing into 6×2 mm holes in acrylic resin blocks, sandblasted with 50 μm Al2O3 and randomly divided into 6 groups according to repair material [Constic (Group C), Fusio Liquid Dentin (Group FLD), Universal bonding+Universal composite (Group Control), Alloy Primer+Constic (Group APC), Alloy Primer+Fusio Liquid Dentin (Group APFLD), Alloy Primer+Universal bonding+Universal composite (Group APControl)]. After shear bond strength test, the fracture modes were determined under a digital microscope. Statistical analysis was performed using one-way analysis of variance and Tukey's post hoc test. Results: The highest shear bond strength values were obtained for Fusio Liquid Dentin, among the three repair materials when Alloy Primer was not applied (p&lt;0.05). Usage of Alloy Primer increased shear bond strength values of the investigated repair materials to amalgam, except Fusio Liquid Dentin. Conclusion: Within the limitations of the present research, it can be concluded that; the investigated self-adhesive composite materials could be time-saving alternatives to the Universal bonding+Universal composite for the purpose of amalgam repair, in terms of shear bond strength. The clinicians could prefer Fusio Liquid Dentin self-adhesive composite material without Alloy Primer application for the purpose of amalgam repair in non-cooperative patients.

Impact of MRI Selection on Triage of Endovascular Therapy in Acute Ischemic Stroke: The MRI in Acute Management of Ischemic Stroke (MIAMIS) Registry

Background: The recently published multicenter randomized DAWN trial confirmed greater outcome benefit of endovascular therapy (ET) for anterior circulation large vessel occlusion ischemic stroke from 6 to 24 h from symptom onset compared to medical management in patients selected by advanced imaging with MRI or perfusion CT to identify mismatch between clinical deficit and infarct volume, which represents salvageable penumbra. The debate of CT over MRI is usually the potentially increase time consumption and the difficulty in establishing an adequate standardized workflow utilizing MRI during the hyperacute phase. Purpose: While CT-based selection of patients is the current standard of care, we sought to determine the time impact of the alternative approach of MRI selection in the 0–12 h window. Methods: In the MRI in Acute Management of Ischemic Stroke (MIAMIS) registry, we retrospectively analyzed 89 consecutive patients from January 2008 to January 2010 who presented with acute stroke symptoms with a National Institutes of Health Stroke Scale score ≥5 or aphasia within 0–12 h from symptom onset. The presence of penumbra was determined by MR perfusion-diffusion mismatch or clinical diffusion mismatch. Patients were stratified based on the presence of mismatch and clinical outcomes in patients who received ET. Imaging times were recorded. Results: The MRI turnaround time was 95.5 ± 48.5 min. The total MRI time was 27.7 ± 12.8 min. Seventeen (19.1%) patients were found to have nonvascular etiology. Mismatch was found in 35 (48.6%) patients with acute ischemic stroke (AIS). Patients with nonvascular etiology were younger (55.7 vs. 65.6 years, p < 0.02), without any vessel occlusion or mismatch noticed in this group. We dichotomized the 39 AIS patients with vessel occlusion into two subgroups: these with mismatch and these without. Patients without mismatch were older (76.7 vs. 64.4 years, p < 0.05), more likely to have congestive heart failure (71.4 vs. 22%, p < 0.03), a higher total serum cholesterol level (196 vs. 156 mg/dL, p < 0.04), and medium to large lesions on diffusion-weighted imaging (DWI) (85.7 vs. 37.5%, p < 0.04). Conclusions: Multimodality MRI screening for AIS symptoms for ET is feasible. Optimizing each center’s protocol and the utilization of MRI with DWI only may be a time-saving alternative.

The effect of bone choice on quantification of mineralization in broiler chickens up to 6 weeks of age

An experiment was conducted to assess the most appropriate bone type for measuring bone mineralization in male broiler chicks up to 42 d. A total of 72 male broilers were raised in 0.64 m2 pens on a litter floor. The study design included 2 dietary treatments (Control and Low) containing differing levels of total phosphorus (7.8 and 4.4 g/kg for Control and Low diets respectively) and calcium (22.7 and 13.1 g/kg for Control and Low diets respectively) with each fed to 6 replicate pens of 6 birds. Each wk, 6 birds per diet were euthanized and leg bones removed to measure ash percentage. Foot, toe, tibia, and femur ash were compared using the mean of both legs from each bird, via t-tests to separate Control and Low diets. At the end of wk 1, diets could not be separated using any of the bone ash measures. From wk 2 to wk 5, both tibia and foot ash differentiated between the Control and Low diets, and tibia continued to show significant differences between the diets into wk 6. Femur ash did not show any dietary differences until wk 3, but then showed significant differences between the diets until wk 6. Toe ash only differentiated between diets at wk 2, and variation both within and between birds was high, particularly with younger birds. These results suggest that bird age has implications when choosing a bone for assessing possible differences in dietary phosphorus and calcium uptake. Femur ash may be more appropriate for showing differences in broilers aged 6 wk and older. Foot ash provides a comparable alternative to tibia ash in birds aged 2 to 5 wk of age, providing a labor- and time-saving alternative.

Dutasteride add-on therapy reduces detrusor mass in patients with benign prostatic enlargement not satisfied with alpha-adrenergic antagonist monotherapy: A single center prospective study.

The ultrasound assessment of bladder wall thickness (BWT) and intravesical prostatic protrusion (IPP) have emerged as a non-invasive, inexpensive, time-saving alternatives to pressure-flow studies to assess benign prostatic obstruction (BPO). Aim of our study was to evaluate the effect on detrusor mass of dutasteride add-on therapy in men with lower urinary tract symptoms (LUTS) and benign prostatic enlargement (BPE). A consecutive series of BPE patients with a prostate volume (PV) ≥30 mL and an international prostate symptoms score (IPSS) ≥8 not satisfied with Tamsulosin monotherapy were enrolled. Free maximum flow (Qmax), PV, BWT, and IPP were recorded at baseline and at 24 weeks follow-up. Overall, 27 men were enrolled. Dutasteride significantly improved LUTS (-46.7%; P = 0.001) and Qmax (+18.7%; P = 0.001) and reduced PV (-13%; P = 0.002), BWT (-40.3%; P = 0.001), and IPP (-14.9%; P = 0.015). At baseline, based on BWT ≥5 mm and an IPP >10 mm, 13/27 (48%) and 15/27 (55%) patients were defined at risk for BPO, respectively; while after 24 weeks of treatment they were 3/27 (11.1%) and 11/27 (40%), respectively. Dutasteride add-on therapy significantly reduced IPP and detrusor mass and was effective in improving LUTS in patients with BPE not satisfied with αBs monotherapy. The possible role of BWT and IPP as proxies of medical treatment outcomes should be confirmed by further studies.

Voltammetric Study and Electrodeposition of Zinc in Hydrophobic Room-Temperature Ionic Liquid 1-Butyl-1-methylpyrrolidinium Bis((trifluoromethyl)sulfonyl)imide ([BMP][TFSI]): A Comparison between Chloride and TFSI Salts of Zinc

The voltammetric behavior, nucleation mechanism, and electrodeposition of zinc were carefully studied in hydrophobic room-temperature ionic liquid 1-butyl-1-methylpyrrolidinium bis((trifluoromethyl)sulfonyl)imide (RTIL [BMP][TFSI]). The Zn(II) species were introduced via the anodic dissolution of Zn, or the addition of Zn(TFSI)2 and ZnCl2, respectively. Unexpectedly, ZnCl2 shows a high solubility in [BMP][TFSI] where most metal chlorides are almost insoluble. For electrodeposition, ZnCl2 hence can be used as a cheaper and time-saving alternative of the Zn(II) source. Two Zn salts show obviously different voltammetric behavior, which may result from the different Zn(II) species formed. Two redox couples of Zn(II) are observed in ZnCl2 solutions but there is only one redox couple in Zn(TFSI)2 solutions. Many phenomena imply that two Zn(II) species, one is partially Cl-coordinated and the other one is TFSI-coordinated, are produced from ZnCl2. The surface morphology of Zn deposits prepared from the two Zn salts at 80°C is not distinguishable but apparently changed with the electrodepositing potential. Similarly, the nucleation mechanism is independent of the Zn salts, and a 3-dimensional (3D) progressive nucleation with diffusion controlled growth is observed. Oppositely, the deposition/stripping efficiency of Zn is significantly influenced by the source of Zn(II); a much higher efficiency is observed in the Zn(TFSI)2 solutions.

‘Our time to act has come’: desynchronization, social media time and protest movements

Protest movements have successfully adopted media technologies to promote their causes and mobilize large numbers of supporters. Especially social media that are considered as low-cost and time-saving alternatives have played particularly important roles in recent mobilizations. There is, however, a growing concern about the contradictions between long-term organizing for progressive, social change, on one hand, and the media technologies employed, on the other. Hartmut Rosa has argued that the current culture of accelerated capitalism is characterized by a growing desynchronization between political practices (slow politics) and the economic system (fast capitalism). This article traces the increasing social acceleration related to (media) technologies employed by protest activists and asks whether there is an increasing desynchronization with their political practices discernible. Furthermore, the article investigates strategies of resistance to overcome the growing gap between ‘machine time’ and political time. Empirically, the article builds on archival material and in-depth interviews documenting the media practices of the unemployed workers’ movement (1930s), the tenants’ movement (1970s) and the Occupy Wall Street Movement (2011/2012) and argues for the need to re-politicize media infrastructures as means of communication in order to tackle democratic problems that emerge from the divergent temporalities.

New cassettes for single-step drug resistance and prototrophic marker switching in fission yeast.

Construction of multiply mutated strains for genetic interaction analysis and of strains carrying different epitope tags at multiple open reading frames for testing protein localization, abundance and protein-protein interactions is hampered by the availability of a sufficient number of different selectable markers. Moreover, strains with single gene deletions or tags often already exist in strain collections; for historical reasons these will mostly carry the ura4(+) gene or the G418-resistance kanMX as marker. Because it is rather cumbersome to produce multiply deleted or tagged strains using the same marker, or to completely reconstruct a particular strain with a different marker, single-step exchange protocols of markers are a time-saving alternative. In recent years, dominant drug resistance markers (DDRMs) against clonNAT, hygromycin B and bleomycin have been adapted and successfully used in Schizosaccharomyces pombe. The corresponding DDRM cassettes, natMX, hphMX and bleMX, carry the TEF promotor and terminator sequences from Ashbya gossypii as kanMX; this provides flanking homologies to enable single-step marker swapping by homologous gene targeting. To expand this very useful toolset for single-step marker exchange, I constructed MX cassettes containing the nutritional markers arg3(+), his3(+), leu1(+) and ura4(+). Furthermore, a set of constructs was created to enable single-step exchange of ura4(+) to kanMX6, natMX4 and hphMX4. The functionality of the cassettes is demonstrated by successful single-step marker swapping at several loci. These constructs allow straightforward and rapid remarking of existing ura4(+) - and MX-deleted and -tagged strains.

In vitro comparative assessment of different viability assays in Acanthamoeba castellanii and Acanthamoeba polyphaga trophozoites

The species of the genus Acanthamoeba are opportunistic protozoan parasites that cause different diseases in humans, such as amoebic keratitis and granulomatous encephalitis. The rise in the rate of Acanthamoeba keratitis, mainly due to the increase in contact lens wearers, turns the development of viability assays using a multi-well plate reader as a tool for screening new antiamoebic agents in vitro into an important goal. In our study, the viability assays PrestoBlue®, resazurin sodium salt, 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide (MTT) and CellTiter96® were tested for their suitability as time-saving alternatives to the classical manual or direct-counting method, assessing the effect of the antiamoebic agent chlorhexidine digluconate and temperature on Acanthamoeba castellanii (ATCC® 30234™) and Acanthamoeba polyphaga 2961. Although resazurin and MTT have already been previously used in amoeba viability assays to test the activities of antiamoebic agents in vitro, it is the first time that PrestoBlue® and CellTiter96® are used for this purpose. Results indicated that the viability assays were strain-dependent leading in some cases to an overestimation of the real situation of viable cells. This implies that each viability assay ought to be set up for each amoeba strain studied.

Thyroid surgery: comparison between the electrothermal bipolar vessel sealing system, harmonic scalpel, and classic suture ligation

Background This study was conducted to compare the outcome of total thyroidectomy using the electrothermal bipolar vessel sealing system, the harmonic scalpel, and the classic suture ligation technique. Methods This was a retrospective study of prospectively collected data from 382 consecutive total thyroidectomies from September 2004 to August 2006. Patients were divided into 3 groups: group SL patients (n = 90) underwent total thyroidectomy with the classic suture ligation technique, group L (n = 148) with the electrothermal bipolar vessel sealer, and group U (n = 144) with the harmonic scalpel. The main outcomes measured were surgical and hospitalization time, intraoperative and postoperative bleeding, postoperative hypocalcemia, and superior and inferior laryngeal nerves injuries. Results The 3 groups were similar in terms of demographics, thyroid gland weight and pathology, perioperative complications, and hospital stay. Compared with the classic technique, surgical time was reduced significantly by about 20% when the bipolar vessel sealer or harmonic scalpel was used (93.3 ± 12.5 vs 74.3 ± 14.2 and 73.8 ± 13.8 min, P = .001, and P = .001, respectively). Conclusions Both the bipolar vessel sealer and harmonic scalpel are safe, useful, and time-saving alternatives to the traditional suture ligation technique for thyroid surgery. Because no differences were observed regarding these 2 devices, the choice should be made based on the surgeon’s preferences and experience.

Critical Analysis of Dimension Reduction by a Moment Closure Method in a Population Density Approach to Neural Network Modeling

Computational techniques within the population density function (PDF) framework have provided time-saving alternatives to classical Monte Carlo simulations of neural network activity. Efficiency of the PDF method is lost as the underlying neuron model is made more realistic and the number of state variables increases. In a detailed theoretical and computational study, we elucidate strengths and weaknesses of dimension reduction by a particular moment closure method (Cai, Tao, Shelley, & McLaughlin, 2004; Cai, Tao, Rangan, & McLaughlin, 2006) as applied to integrate-and-fire neurons that receive excitatory synaptic input only. When the unitary postsynaptic conductance event has a single-exponential time course, the evolution equation for the PDF is a partial differential integral equation in two state variables, voltage and excitatory conductance. In the moment closure method, one approximates the conditional kth centered moment of excitatory conductance given voltage by the corresponding unconditioned moment. The result is a system of k coupled partial differential equations with one state variable, voltage, and k coupled ordinary differential equations. Moment closure at k = 2 works well, and at k = 3 works even better, in the regime of high dynamically varying synaptic input rates. Both closures break down at lower synaptic input rates. Phase-plane analysis of the k = 2 problem with typical parameters proves, and reveals why, no steady-state solutions exist below a synaptic input rate that gives a firing rate of 59 s(1) in the full 2D problem. Closure at k = 3 fails for similar reasons. Low firing-rate solutions can be obtained only with parameters for the amplitude or kinetics (or both) of the unitary postsynaptic conductance event that are on the edge of the physiological range. We conclude that this dimension-reduction method gives ill-posed problems for a wide range of physiological parameters, and we suggest future directions.

Population density methods for large-scale modelling of neuronal networks with realistic synaptic kinetics: cutting the dimension down to size

Population density methods provide promising time-saving alternatives to direct Monte Carlo simulations of neuronal network activity, in which one tracks the state of thousands of individual neurons and synapses. A population density method has been found to be roughly a hundred times faster than direct simulation for various test networks of integrate-and-fire model neurons with instantaneous excitatory and inhibitory post-synaptic conductances. In this method, neurons are grouped into large populations of similar neurons. For each population, one calculates the evolution of a probability density function (PDF) which describes the distribution of neurons over state space. The population firing rate is then given by the total flux of probability across the threshold voltage for firing an action potential. Extending the method beyond instantaneous synapses is necessary for obtaining accurate results, because synaptic kinetics play an important role in network dynamics. Embellishments incorporating more realistic synaptic kinetics for the underlying neuron model increase the dimension of the PDF, which was one-dimensional in the instantaneous synapse case. This increase in dimension causes a substantial increase in computation time to find the exact PDF, decreasing the computational speed advantage of the population density method over direct Monte Carlo simulation. We report here on a one-dimensional model of the PDF for neurons with arbitrary synaptic kinetics. The method is more accurate than the mean-field method in the steady state, where the mean-field approximation works best, and also under dynamic-stimulus conditions. The method is much faster than direct simulations. Limitations of the method are demonstrated, and possible improvements are discussed.

Field mesocosms for assessing biotic processes in soils: How to avoid side effects

Field mesocosms can overcome the simplicity and deficiencies of laboratory based experimental designs. This study deals with a number of possible side effects of a mesocosm technique that involves deep-freezing of soil monoliths to eliminate soil fauna, wrapping in nets of various mesh-size to control faunal immigration and replanting in the field. We used Berlese-Tullgren sets in the field to directly inoculate mesocosms with microarthropods. After 6 months of exposure, the number of collembolans equalled control level whereas immigration and inoculation of oribatids accounted for only 30% of the control. The number of ciliates, their distribution into feeding groups, and the numbers of nematodes, tardigrades and rotifers were not significantly affected by the elimination of mesofauna. We also did not detect significant treatment specific effects on microclimatic conditions within the litter layer of the mesocosms. Furthermore, we compared the monolith approach with a technique using sieved soil as a time-saving alternative. Water capacity and infiltration rate of mesocosms made of sieved soil did not differ from mesocosms made of monoliths, but NH 4 + losses were significantly higher in sieved soil when defaunated by deep-freezing. We conclude that the investigated mesocosm technique has little side effects and recommend the use of monoliths in mesocosm studies.