Deterministic and statistical characterization of rigid frame porous materials from impedance tube measurements.

A method to characterize macroscopically homogeneous rigid frame porous media from impedance tube measurements by deterministic and statistical inversion is presented. Equivalent density and bulk modulus of the samples are reconstructed with the scattering matrix formalism, and are then linked to its physical parameters via the Johnson-Champoux-Allard-Lafarge model. The model includes six parameters, namely the porosity, tortuosity, viscous and characteristic lengths, and static flow and thermal permeabilities. The parameters are estimated from the measurements in two ways. The first one is a deterministic procedure that finds the model parameters by minimizing a cost function in the least squares sense. The second approach is based on statistical inversion. It can be used to assess the validity of the least squares estimate, but also presents several advantages since it provides valuable information on the uncertainty and correlation between the parameters. Five porous samples with a range of pore properties are tested, and the pore parameter estimates given by the proposed inversion processes are compared to those given by other characterization methods. Joint parameter distributions are shown to demonstrate the correlations. Results show that the proposed methods find reliable parameter and uncertainty estimates to the six pore parameters quickly with minimal user input.

On describing the optoelectronic characteristics of poly(benzodithiophene-co-quinoxaline)-fullerene complexes: the influence of optimally tuned density functionals.

Here, we investigate the effects of both tuning the range-separation parameter of long-range corrected (LRC) density functionals and including dispersion corrections on describing the local optoelectronic properties of polymer-fullerene interfaces that are critical to the performance of polymer solar cells (PSCs). Focusing on recently studied (Chen, et al., Chem. Mater., 2012, 24, 4766-4772) PSC active layers derived from poly(benzodithiophene-co-quinoxaline) and substituted fullerene PC71BM, we compare the performance of global hybrid functionals (B3LYP and B3LYP-D) alongside two LRC functionals (ωB97X and ωB97X-D) and their optimally tuned (OT) analogs (OT-ωB97X and OT-ωB97X-D). Our results confirm that OT-LRC functionals generally improve the description of the optical properties of the individual materials with respect to experiment. For electron-donor (eD)-electron-acceptor (eA) complexes used to describe the local optoelectronic properties of the material interface, PC71BM is found to preferentially settle near the quinoxaline acceptor units on the copolymer backbone, regardless of the functional, though dispersion corrections have a strong influence on the intermolecular distances and, in turn, the nature of the excited states. All functionals yield very similar descriptions of the transition maxima for the complexes, i.e. predominant local excitations on the copolymer. Importantly, tuning the range-separation parameter of the LRC functional is shown to have a profound effect, as the OT functionals allow for the description of the charge transfer states of the eD-eA complexes, while the non-tuned LRC functionals predict only local intramolecular excitations. These results hold considerable importance for deriving the appropriate physical understanding of the interfacial structure-property-function relationships of PSCs.

Electronic structure of p-type perylene monoimide-based donor-acceptor dyes on the nickel oxide (100) surface: a DFT approach.

A p-type dye-sensitized solar cell, where the dye injects a hole into the semiconductor, could be combined with a typical Grätzel cell to create an efficient tandem device. However, the current p-type devices suffer from low efficiency. Here, geometries and electronic structures of four perylenemonoimide-based dyes () both as free and adsorbed on the NiO(100) semiconductor surface have been investigated to gain a better understanding of the p-type devices. In particular, the electronic transitions relevant to charge transfer between the dye and the surface have been identified. Excitations have been evaluated using the time-dependent DFT calculations, and the roles of frontier orbitals and band edges in transitions have been assessed. The adsorbed dyes can adopt either upright or slightly tilted geometries depending on the structure of the anchoring group and the binding mode of the dye. The adsorption slightly lowers the NiO band gap, from 4.06 eV to 3.90-3.96 eV, depending on the surface-adsorbate system and the band gaps of the dye molecules by 0.1-0.2 eV. Additionally, the adsorption mode of dye moves the LUMO+1 level down by 0.5 eV. The effective mass of charge carrier holes is significantly smaller at the NiO surface than in the bulk indicating the importance of surface conductivity. We also found that the potential drop, i.e. the driving force for charge transfer from NiO to the dye molecule, depends on the adsorption mode of .

Modeling of photoactive conjugated donor-acceptor copolymers: the effect of the exact HF exchange in DFT functionals on geometries and gap energies of oligomer and periodic models.

Conjugated copolymers with an alternating donor-acceptor (D-A) architecture are exploited as low-bandgap and high-hole-mobility materials in organic electronics. However, several of the presently available modeling methods predict different geometries and electronic properties for the same copolymer. In this work, the effect of the amount of exact Hartree-Fock (HF) exchange in density functionals on the planarity of the geometry and the electronic properties of the single oligomer chains of one benzodithiophene- and benzotriazole-based donor-acceptor copolymer and two fluorene-, thiophene-, and benzotriazole-based donor-acceptor copolymers is assessed. The functionals are B3LYP, PBE, PBE0, HSE06, LC-ωPBE, ωB97XD, M06, M06L, M062X, M06HF, and the optimally tuned OT-ωB97X. Benchmarking of the methods is useful for understanding the results of a particular functional and allows, to a certain degree, comparison between results obtained with different functionals. Additionally, the applicability of the one-dimensional periodic boundary condition (PBC) for modeling the D-A copolymers with long constitutional repeating units (CRUs) is evaluated.

Cortical bone thickness can adapt locally to muscular loading while changing with age.

Mechanical loading of muscle action is concentrated at muscle attachment sites; thus there may be a potential for site-specific variation in cortical bone thickness. Humeri from an early 20th-century Finnish (Helsinki) and two medieval English (Newcastle, Blackgate and York, Barbican) populations were subjected to pQCT scanning to calculate site-specific cross-sectional cortical bone area (CA) for four locations and to measure cortical thickness at muscle attachment sites and non-attachment sites. We found that CA at 80% of humerus length was significantly reduced compared to more distal cross-sections, which can be due to reduced stresses at the proximal shaft. The principal direction of loading at 80% humerus length was towards mediolateral plane, likely due to fixing the humerus close to the torso. At 35% the main direction of loading was towards anteroposterior plane, reflecting elbow flexing forces. The principal direction of loading varied between populations, sides and sexes at 50% humerus length due to preference between elbow and shoulder joint; thus this location might be useful when trying to infer differences in activity. These changes are likely due to overall shaft adaptation to forces acting at the humerus. In addition, we found a potential for site-specific variation in cortical thickness; cortical bone at muscle attachment sites was significantly thicker compared to non-attachment sites. Lastly, CA at 35% of humerus length and cortical thickness at non-attachment sites decreased with age. These results underline the importance of muscle loading for bone mass preservation as well as indicate that a site-specific variation of bone mass is possible.

A randomised controlled trial comparing sugammadex and neostigmine at different depths of neuromuscular blockade in patients undergoing laparoscopic surgery.

Deep neuromuscular blockade during certain surgical procedures may improve operating conditions. Sugammadex can be used to reverse deep neuromuscular blockade without waiting for spontaneous recovery. This randomised study compared recovery times from neuromuscular blockade induced by rocuronium 0.6 mg.kg(-1), using sugammadex 4 mg.kg(-1) administered at 1-2 post-tetanic count (deep blockade) or neostigmine 50 µg.kg(-1) (plus atropine 10 µg.kg(-1)) administered at the re-appearance of the second twitch of a train-of-four stimulation (moderate blockade), in patients undergoing laparoscopic surgery. The primary efficacy variable was the time from the start of sugammadex/neostigmine administration to recovery of the train-of-four ratio to 0.9. Patients receiving sugammadex recovered 3.4 times faster than patients receiving neostigmine (geometric mean (95% CI) recovery times of 2.4 (2.1-2.7) and 8.4 (7.2-9.8) min, respectively, p<0.0001). Moreover, 94% (62/66) of sugammadex-treated patients recovered within 5 min, vs 20% (13/65) of neostigmine-treated patients, despite the difference in the depth of neuromuscular blockade at the time of administration of both drugs. The ability to provide deep neuromuscular blockade throughout the procedure but still permit reversal at the end of surgery may enable improved surgical access and an enhanced visual field.

Mortality in out-of-hospital cardiac arrest patients has decreased in the era of therapeutic hypothermia.

BACKGROUND: Mild therapeutic hypothermia (TH) improves survival after out-of-hospital cardiac arrest (OHCA). This treatment was implemented in most Finnish intensive care units (ICUs) in 2003. The aim of this study was to find out whether hospital mortality of ICU-treated OHCA patients has changed in the era of TH. METHODS: This was a retrospective study of data collected prospectively into the database of the Finnish Intensive Care Consortium during the years 2000-2008. The study population consisted of 3958 patients for whom cardiac arrest was registered as the reason for ICU admission and who were transferred to the ICU from the emergency department. We divided the patients into those treated in the pre-hypothermia era (2000-2002) and those treated in the hypothermia era (2003-2008). We investigated whether the treatment period had any impact on hospital mortality. RESULTS: There were no differences between the periods regarding the age or initial Glasgow Coma Scores of the patients. Mean severity of illness was higher in the latter period. Despite this, mortality decreased: the hospital mortality rate was 57.9% in 2000-2002 and 51.1% in 2003-2008, P < 0.001. In a multivariate logistic regression analysis, treatment in 2003-2008 was associated with a reduced risk of in-hospital death (adjusted odds ratio 0.54, 95% confidence interval 0.45-0.64 and P < 0.001). Survival improved markedly between the years 2002 and 2003. This improvement has persisted, but there has been no further improvement. CONCLUSION: Concurrently with the implementation of TH, hospital mortality of OHCA patients treated in Finnish ICUs decreased.

Metabolic syndrome, periodontal infection, and dental caries.

Only a few studies have examined the association of metabolic syndrome with periodontal infection and dental caries. The aim in this study was to examine the association of metabolic syndrome with periodontal infection and dental caries using the European Group for the Study of Insulin Resistance (EGIR) definition and its separate components. This study population consisted of dentate, non-diabetic individuals aged 30 to 64 years (N = 2050) who had never smoked. Relative risks (RR) were estimated with Poisson regression models. Metabolic syndrome was associated with teeth with deepened periodontal pockets 4 mm deep or deeper [adjusted RR 1.19 (95% CI 1.01-1.42)], with pockets 6 mm deep or deeper [adjusted RR 1.50 (95% CI 0.96-2.36)], and carious teeth [adjusted RR 1.25 (95% CI 0.93-1.70)]. The results suggest that metabolic syndrome or some of its components are associated weakly with periodontal infection.

Scandinavian clinical practice guidelines for therapeutic hypothermia and post-resuscitation care after cardiac arrest.

BACKGROUND AND AIM: Sudden cardiac arrest survivors suffer from ischaemic brain injury that may lead to poor neurological outcome and death. The reperfusion injury that occurs is associated with damaging biochemical reactions, which are suppressed by mild therapeutic hypothermia (MTH). In several studies MTH has been proven to be safe, with few complications and improved survival, and is recommended by the International Liaison of Committee on Resuscitation. The aim of this paper is to recommend clinical practice guidelines for MTH treatment after cardiac arrest from the Scandinavian Society of Anaesthesiology and Intensive Care Medicine (SSAI). METHODS: Relevant studies were identified after two consensus meetings of the SSAI Task Force on Therapeutic Hypothermia (SSAITFTH) and via literature search of the Cochrane Central Register of Controlled Trials and Medline. Evidence was assessed and consensus opinion was used when high-grade evidence (Grade of Recommendation, GOR) was unavailable. A management strategy was developed as a consensus from the evidence and the protocols in the participating countries. RESULTS AND CONCLUSION: Although proven beneficial only for patients with initial ventricular fibrillation (GOR A), the SSAITFTH also recommend MTH after restored spontaneous circulation, if active treatment is chosen, in patients with initial pulseless electrical activity and asystole (GOR D). Normal ethical considerations, premorbid status, total anoxia time and general condition should decide whether active treatment is required or not. MTH should be part of a standardized treatment protocol, and initiated as early as possible after indication and treatment have been decided (GOR E). There is insufficient evidence to make definitive recommendations among techniques to induce MTH, and we do not know the optimal target temperature, duration of cooling and rewarming time. New studies are needed to address the question as to how MTH affects, for example, prognostic factors.

Measurement of surgical stress in anaesthetized children.

BACKGROUND: The surgical stress index (SSI), derived from a combination of heart rate (HR) and photoplethysmographic amplitude (PPGA) time series, is a novel method for continuous monitoring of intraoperative stress and has been validated in adults. The applicability of SSI and its constituents to monitoring children has not been previously evaluated. METHODS: In this controlled trial, 22 anaesthetized patients, aged 4-17 yr, undergoing strabismus surgery were randomized into two groups, Group LL and Group BSS. Patients in Group LL received topical conjunctival anaesthesia with a 1:1 mixture of lidocaine 2% and levobupivacaine 0.75%, and patients in Group BSS received balanced salt solution. RESULTS: Endotracheal intubation (n=22) increased median (range) SSI from 39.2 (22.6-55.6) to 53.6 (35.8-63.3) (P<0.001), decreased PPGA from 5.62 (2.79-9.69) to 5.27 (2.59-7.54)% (P=0.001), and increased the difference of response entropy (RE) and state entropy (SE) of frontal biopotentials (RE-SE) from 3.1 (0.06-9.1) to 5.7 (0.6-9.4) (P=0.01). Conventional haemodynamic variables also increased, median (range) HR from 72.9 (56.7-113.8) to 84.2 (60.4-124.8) beats min(-1) (P<0.001), and systolic non-invasive arterial pressure (S-NIBP) from 87 (78-143) to 103 (79-125) (P=0.007). When 3 min baseline before surgery was compared with 12 min of surgery, median (range) SSI increased from 43.3 (31.2-58.0) to 49.9 (39.3-57.2) (P=0.042) vs from 46.6 (26.8-57.8) to 52.1 (31.7-60.1) (P=0.024) and PPGA decreased from 6.60 (3.10-8.24) to 5.80 (3.03-7.65)% (P<0.001) vs from 5.51 (3.25-9.84) to 5.06 (3.08-8.99)% (P=0.042), in Groups LL and BSS, respectively, but SSI or other indicators did not differ significantly between the groups. CONCLUSIONS: SSI, PPGA, HR, NIBP, RE, and RE-SE detect autonomic responses to nociceptive stimuli in anaesthetized children undergoing strabismus surgery.

I.V. ropivacaine compared with lidocaine for the treatment of tinnitus.

BACKGROUND: I.V. lidocaine has been used to ameliorate tinnitus, but in general its effect has been limited. The longer acting local anaesthetic ropivacaine may be more effective. METHODS: A total of 19 randomized, double-blind, cross-over study patients suffering from chronic tinnitus were given a 30 min i.v. infusion of ropivacaine or lidocaine 1.5 mg kg(-1) at an interval of 2-3 months. The intensity of tinnitus was evaluated on tinnitus handicap inventory (THI) scale and on the visual analogue scale (VAS). Plasma ropivacaine and lidocaine concentrations were determined. RESULTS: In both treatments, the infusion decreased the VAS score significantly. At the end of infusion, a > or =50% reduction in VAS score was observed in five patients by ropivacaine and in one patient by lidocaine, but this effect was sustained for 1 h only in three patients. However, the THI scores did not differ significantly within or between treatments. On the post-infusion day, three patients after ropivacaine and five after lidocaine treatment had > or =30% improvement in the THI score. Four weeks later, one patient after ropivacaine and two after lidocaine had a > or =30% reduction in the THI score. One patient developed seizures soon after ropivacaine infusion from which he recovered uneventfully. His plasma concentration of ropivacaine was 1817 ng ml(-1). The highest individual ropivacaine and lidocaine concentrations were 3483 and 1680 ng ml(-1), respectively. CONCLUSIONS: Temporary clinically significant alleviation of tinnitus was observed only in a few individuals after both i.v. ropivacaine and lidocaine. The toxicity of ropivacaine limits its usefulness.

Auditory-evoked potentials in bispectral index-guided anaesthesia for cardiac surgery.

BACKGROUND AND OBJECTIVE: Midlatency auditory-evoked potentials, as measures of the anaesthetic state, were evaluated at similar levels of bispectral index in cardiac surgical patients maintained with either propofol or isoflurane anaesthesia. METHODS: Twenty-four patients were randomly allocated to anaesthesia with propofol (n = 12) or isoflurane (n = 12). Bispectral index was maintained below 60 during surgery. Auditory-evoked potentials were collected before induction of anaesthesia, 10 min after intubation, 30 min after sternotomy, during cardiopulmonary bypass at the time of cross-clamping of the aorta and during stable mild hypothermia, after de-clamping of the aorta, and after the operation. RESULTS: At the pre-determined time points, bispectral index values showed comparable depth of hypnosis in both groups. The latency of the Nb component of midlatency auditory-evoked potentials was significantly increased in the isoflurane group after intubation (P < 0.001) and that of both the Nb and the Pa components after sternotomy (P < 0.001) compared with the propofol group. No differences between the groups were detected with respect to haemodynamic variables. No patient reported recall of intraoperative events. CONCLUSION: After intubation and surgical stimulation, when bispectral index was at a constant level, there was a difference in the Nb and Pa components of the midlatency auditory-evoked potentials between the two anaesthetic regimens, indicating a distinction in the state of anaesthesia. Our results suggest that the parallel use of these two electrophysiological methods can show differences in the components of anaesthesia between various anaesthesia methods in cardiac surgical patients.

Intensive care of the elderly in Finland.

BACKGROUND: The ageing of the population will increase the demand for health care resources. The aim of this study was to determine how age affects resource consumption and outcome of intensive care in Finland. METHODS: Data on 79,361 admissions to 26 Finnish intensive care units (ICUs) during the years 1998-2004 were analysed. The severity of illness was measured using Simplified Acute Physiology II scores and the intensity of care using Therapeutic Intervention Scoring System scores. RESULTS: The median age was 62 years; 8.9% of patients were aged 80 years or over. The hospital mortality rate was 16.2% in the overall patient population, but 28.4% in patients aged 80 years or over. Old age was an independent risk factor for hospital mortality. The mean intensity of care was at its highest in the age groups 60-69, 70-74 and 75-79 years. It was notably lower for patients aged 80 years or over. If the need for intensive care remains unchanged in each age group, the change in the age distribution of the Finnish population will increase the demand for ICU beds by 19% by the year 2020 and by 25% by the year 2030. CONCLUSION: The hospital mortality rate increases with increasing age. The mean intensity of care is lower for the oldest patients than for patients aged less than 80 years. The ageing of the population will probably cause a remarkable increase in the need for intensive care in the near future.

Fatal inhalation injury caused by airway fire during tracheostomy.

A 45-year-old man needed emergency tracheostomy and cranioplasty. He was intubated with a cuffed oral polyvinylchloride endotracheal tube and ventilated with 100% oxygen before tracheal incision. During opening of the trachea using diathermy, a popping sound was heard and flames originating from the tracheal incision were observed. The endotracheal tube was charred and its lumen had melted. Immediately after the incident, bronchofibroscopic examination revealed inhalation injury. After remaining for 8 weeks in hospital, the patient was transferred to a health care centre, where he was found dead in his bed.

Outcome from intensive care after cardiac arrest: comparison between two patient samples treated in 1986-87 and 1999-2001 in Finnish ICUs.

BACKGROUND: The aim of the study was to find out whether the characteristics of patients and the outcome from intensive care after cardiac arrest have changed over time. METHODS: Two nationwide databases were compared: (i) The Finnish National Intensive Care Study data in 1986-87 and (ii) data on 28,640 admissions to Finnish ICUs in 1999-2001. Patients whose reason for ICU admission was cardiac arrest were included. The former study included 604 patients treated in 18 medical and surgical ICUs in and the latter 1036 patients in 25 medical and surgical ICUs. Data on the components of Acute Physiology and Chronic Health Evaluation (APACHE II) were prospectively collected in both study periods. Logistic regression analysis was used to test the independent contribution of the study period on hospital mortality. RESULTS: In 1986-87, patients were younger and the proportion of males was lower than in 1999-2001. The hospital mortality in 1986-87 was 61.3% and in 1999-2001 59.1% (P= 0.396). Among patients aged < 57 years, the hospital mortality in 1986-87 was 62.1% and in 1999-2001 48.8% (P < 0.01). In multivariate analysis, controlling for age, gender, Glasgow coma score (GCS), chronic health evaluation points and source of admission, treatment during 1986-87 was an independent predictor for hospital death among all patients (OR 1.273; 95% CI 1.015-1.594), those aged < 57 years (OR 1.959; 95% CI 1.270-3.021) and among males (OR 1.384; 95% CI 1.050-1.825). CONCLUSION: Since the late 1980s, the outcome from intensive care after cardiac arrest may have improved especially among younger patients and males.

Allocation of tasks between anesthesiologists and anesthesia nurses in Finland.

BACKGROUND: The shortage of anesthesiologists in Finland is worsening. A survey was carried out in 2003 among head anesthesiologists and head nurses to clarify current practice and the potentials for reorganizing tasks between anesthesiologists and anesthesia nurses. A national working group analyzed the results. METHODS: A questionnaire concerning doctor and nurse resources in anesthesiology, current allocation of tasks, and opinions on how these tasks could be reallocated was sent to 87 head anesthesiologists and 32 head nurses in 45 different hospitals. The answers from the doctors and nurses were compared. RESULTS: The response rate of doctors and nurses was 87% and 100%, respectively. In the enrolled hospitals there were 64 unoccupied positions for specialists in anesthesiology. The ratio of anesthesiologists to operation rooms (OR) they attended varied between 0.3 and 1.5. Doctors and nurses reported the allocation of tasks quite similarly. The great majority of respondents considered spinal, epidural, and interscalene brachial plexus blocks, and the induction of general anesthesia to be tasks that should be performed by an anesthesiologist. Very few respondents of either profession were willing to reallocate tasks so that nurses could deliver general anesthesia, including endotracheal intubation, even in low-risk patients. CONCLUSION: Nurses could be trained nationwide to perform procedures already performed by locally trained nurses in some hospitals. To cope with the shortage of anesthesiologists, other strategies must be adopted in addition to transferring part of their work load to nurses.

Excess mortality in winter in Finnish intensive care.

BACKGROUND: In the general population, mortality from acute myocardial infarctions, strokes and respiratory causes is increased in winter. The winter climate in Finland is harsh. The aim of this study was to find out whether there are seasonal variations in mortality rates in Finnish intensive care units (ICUs). METHODS: We analysed data on 31,040 patients treated in 18 Finnish ICUs. We measured severity of illness with acute physiology and chronic health evaluation II (APACHE II) scores and intensity of care with therapeutic intervention scoring system (TISS) scores. We assessed mortality rates in different months and seasons and used logistic regression analysis to test the independent effect of various seasons on hospital mortality. We defined 'winter' as the period from December to February, inclusive. RESULTS: The crude hospital mortality rate was 17.9% in winter and 16.4% in non-winter, P = 0.003. Even after adjustment for case mix, winter season was an independent risk factor for increased hospital mortality (adjusted odds ratio 1.13, 95% confidence interval 1.04-1.22, P = 0.005). In particular, the risk of respiratory failure was increased in winter. Crude hospital mortality was increased during the main holiday season in July. However, the severity of illness-adjusted risk of death was not higher in July than in other months. An increase in the mean daily TISS score was an independent predictor of increased hospital mortality. CONCLUSION: Severity of illness-adjusted hospital mortality for Finnish ICU patients is higher in winter than in other seasons.

Supplemental 80% oxygen does not attenuate post-operative nausea and vomiting after breast surgery.

BACKGROUND: Although supplemental oxygen has been shown to be as effective as ondansetron in the prevention of post-operative nausea and vomiting (PONV) in one study in abdominal surgery patients, the antiemetic efficacy of supplemental oxygen is controversial on the basis of studies with other patients. We compared the efficacy of 80% and 30% oxygen in decreasing PONV in breast surgery. Ondansetron was used as an active control. METHODS: Ninety patients were given a standardized sevoflurane anesthetic. They were randomly assigned to three groups: 30% oxygen in nitrogen and saline 2 ml intravenously (i.v.) at the end of surgery (group 30); 80% oxygen in nitrogen and saline 2 ml (group 80); and 30% oxygen in nitrogen and ondansetron 4 mg (group O). Oxygen was administered during surgery and up to 2 h after surgery. RESULTS: The incidence of total response (no retching or vomiting, no nausea) during the first 24 post-operative hours was not different between group 80 (17%) and group 30 (11%) but was higher in group O (43%) than in group 30 (P<0.05). Compared with group O, patients in group 80 experienced more vomiting during the study period 0-24 h (66% vs. 32%; P<0.05) and more nausea during the period 6-24 h (72% vs. 39%; P<0.05). There was no difference between the groups in their risk for PONV, pain scores, opioid consumption, or patient satisfaction. CONCLUSIONS: In this study, supplemental 80% oxygen administration failed to decrease PONV in breast surgery.