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Introducción: el servicio de Kinesiología del Hospital Italiano de Buenos Aires adoptó la virtualidad para la atención de pacientes durante la pandemia de COVID-19. Se decidió realizar una adaptación transcultural del cuestionario de 17 ítems validado al español de España Telemedicine Satisfaction and Usefulness Questionnaire (TSUQ) para conocer la satisfacción de los pacientes. Métodos: dos investigadores nativos realizaron una adaptación del cuestionario TSUQ al español rioplatense. Participaron pacientes atendidos entre mayo de 2021 y marzo de 2022 que habían realizado al menos cuatro sesiones de TR. Fue evaluada la correlación de la puntuación del instrumento resultante con la de un ítem agregado a modo de criterio externo concurrente. La validación del constructo fue llevada a cabo mediante sendos análisis factoriales exploratorios y confirmatorios. Resultados: obtuvimos 293 cuestionarios (media de edad 57 años, 64 % sexo femenino). Luego de los resultados del AFE (Análisis factorial Exploratorio) (n=101), consensuamos eliminar 5 ítems. El cuestionario resultante (12 ítems) fue luego validado en una nueva muestra (n=192) a través de un AFC (Análisis factorial Confirmatorio). La fiabilidad compuesta, la varianza media extractada y la validez convergente fueron adecuadas, mientras que la validez discriminante fue escasa. Documentamos una moderada correlación (Spearman de 0,35, p < 0,0001) entre el puntaje total del cuestionario y el de la pregunta agregada como criterio externo concurrente de validación y una excelente correlación entre versiones. Conclusión: la versión abreviada del cuestionario TSUQ en español tiene propiedades psicométricas adecuadas, lo que lo vuelve un instrumento valioso para evaluar la satisfacción de los pacientes que realizan Tele-Rehabilitación.

The heat and electrical conductivity of Earth’s core matter represent key input quantities for geophysical models of the Earth’s core evolution and geodynamo. Here, the authors show how the scattering due to interactions between electrons has a relatively weak impact on the electrical and thermal conductivities of iron at core conditions.

Coloproctological diseases, including both benign and malignant conditions, are among the most common diagnoses in clinical practice. Several disorders affect both men and women, while others are unique to women, or women are at a greater risk of developing them. This is due to anatomical, biological, and social conditions and also due to females' exclusive capabilities of reproduction and pregnancy. In this context, the same proctological disease could differ between men and women, who can experience different perceptions of health and sickness. There is a raised awareness about the impact of different diseases in women and a growing need for a personalized approach to women's health. In this review, we aim to summarize the specific features of the main coloproctological diseases, specifically in the female population. This includes common complaints during pregnancy, conditions linked to vaginal delivery, functional consequences after colorectal resections, and conditions presenting a gender disposition.

Background: Flywheel resistance training has become more integrated within resistance training programs in a variety of sports due to the neuromuscular, strength, and task-specific enhancements reported with this training., Objective: This paper aimed to present the consensus reached by internationally recognized experts during a meeting on current definitions and guidelines for the implementation of flywheel resistance training technology in sports., Methods: Nineteen experts from different countries took part in the consensus process; 16 of them were present at the consensus meeting (18 May 2023) while three submitted their recommendations by e-mail. Prior to the meeting, evidence summaries were developed relating to areas of priority. This paper discusses the available evidence and consensus process from which recommendations were made regarding the appropriate use of flywheel resistance training technology in sports. The process to gain consensus had five steps: (1) performing a systematic review of systematic reviews, (2) updating the most recent umbrella review published on this topic, (3) first round discussion among a sample of the research group included in this consensus statement, (4) selection of research group members-process of the consensus meeting and formulation of the recommendations, and (5) the consensus process. The systematic analysis of the literature was performed to select the most up-to-date review papers available on the topic, which resulted in nine articles; their methodological quality was assessed according to AMSTAR 2 (Assessing the Methodological Quality of Systematic Review 2) and GRADE (Grading Recommendations Assessment Development and Evaluation). Statements and recommendations scoring 7-9 were considered appropriate., Results: The recommendations were based on the evidence summary and researchers' expertise; the consensus statement included three statements and seven recommendations for the use of flywheel resistance training technology. These statements and recommendations were anonymously voted on and qualitatively analyzed. The three statements reported a score ranging from 8.1 to 8.8, and therefore, all statements included in this consensus were considered appropriate. The recommendations (1-7) had a score ranging from 7.7 to 8.6, and therefore, all recommendations were considered appropriate., Conclusions: Because of the consensus achieved among the experts in this project, it is suggested that practitioners and researchers should adopt the guidelines reported in this consensus statement regarding the use of flywheel resistance technology in sports., (© 2024. The Author(s).)

Background: Sclerotherapy with 3% polidocanol foam is becoming increasingly popular for the treatment of symptomatic I-II or III degree haemorrhoidal disease (HD). However, there are no studies that have reported a follow-up of more than 1 year. The purpose of this study was to analyse the long-term outcomes of sclerotherapy with 3% polidocanol foam in the treatment of II-degree HD., Methods: This was an open label, single-arm, phase 2b trial conducted in 10 tertiary referral centres for HD. A total of 183 patients with II-degree HD, aged between 18 and 75 years with symptomatic HD according to the Goligher classification and unresponsive to medical treatment, were included in the study and underwent sclerotherapy with 3% polidocanol foam. The efficacy was evaluated in terms of bleeding score, haemorrhoidal disease symptom score (HDSS) and short health scale for HD (SHS-HD) score. Successful treatment was defined as the complete absence of bleeding episodes after 7 days (T1) according to the bleeding score., Results: The overall success rate ranged from 95.6% (175/183) at 1 year to 90.2% (165/183) after the final 3 year follow-up. The recurrence rate, based on the primary outcome, ranged from 12% (15/125) to 28% (35/125). The greatest increase in recurrence (15) was recorded between 12 and 18 months of follow-up, then another five between 18 and 24 months. Both the HDSS and the SHS score remained statistically significant (p < 0.001) from a median preoperative value of 11 (10-13) and 18 (15-20) to 0 (0-2) and 4 (0-4), respectively. Symptom-free (HDSS = 0) patients, excluding patients converted to surgery, increased from 55.5% (101/182) at 1 year to 65.1% at 3 years (110/169). There were no intraoperative complications in redo-sclerotherapy nor additional adverse events (AEs) compared to the first 12 months., Conclusions: Sclerotherapy with 3% polidocanol foam is gradually establishing itself in the treatment of bleeding HD due to its repeatability, safety, convenience in terms of direct and indirect costs with the absence of discomfort for the patient as well as AEs rather than an excellent overall success rate., (© 2022 The Authors. Colorectal Disease published by John Wiley & Sons Ltd on behalf of Association of Coloproctology of Great Britain and Ireland.)

Background: The aim of the present study was to evaluate the efficacy and safety of 3% polidocanol foam for treating 2nd-degree haemorrhoids., Methods: A multicentre, open-label, single-arm, phase 2 trial involving 10 tertiary referral centres for haemorrhodal disease (HD) was performed. Between January and June 2019, patients with 2nd-degree haemorrhoids were prospectively included in this study. The primary outcome was to establish the success rate after one sclerotherapy session in terms of complete resolution of bleeding episodes one week after the injection. The Hemorrhoidal Disease Symptom Score (HDSS), the Short Health Scale for HD (SHS-HD) score and the Vaizey incontinence score were used to assess symptoms and their impact on quality of life and continence. Pain after the procedure, subjective symptoms and the amount and type of painkillers used were recorded. Patients were followed up for 1 year., Results: There were 183 patients [111 males; 60.7%, mean age 51.3 ± 13.5 (18-75) years]. Complete resolution of bleeding was reached in 125/183 patients (68.3%) at 1 week and the recurrence rate was 12% (15/125). Thirteen patients (7.4%) underwent a second sclerotherapy session, while only 1 patient (1.8%) had to undergo a third session. The overall 1-year success rate was 95.6% (175/183). The HDSS and the SHS score significantly improved from a median preoperative value of 11 and 18 to 0 and 0, respectively (p < 0.001). There were 3 episodes of external thrombosis. No serious adverse events occurred., Conclusions: Sclerotherapy with 3% polidocanol foam is a safe, effective, painless, repeatable and low-cost procedure in patients with bleeding haemorrhoids., (© 2022. The Author(s).)

Background: The main aim of this study was (1) to find an index to monitor the loading intensity of flywheel resistance training, and (2) to study the differences in the relative intensity workload spectrum between the FW-load and ISO-load., Methods: twenty-one males participated in the study. Subjects executed an incremental loading test in the squat exercise using a Smith machine (ISO-load) or a flywheel device (FW-load). We studied different association models between speed, power, acceleration, and force, and each moment of inertia was used to find an index for FW-load. In addition, we tested the differences between relative workloads among load conditions using a two-way repeated-measures test., Results: the highest r2 was observed using a logarithmic fitting model between the mean angular acceleration and moment of inertia. The intersection with the x-axis resulted in an index (maximum flywheel load, MFL) that represents a theoretical individual maximal load that can be used. The ISO-load showed greater speed, acceleration, and power outcomes at any relative workload (%MFL vs. % maximum repetition). However, from 45% of the relative workload, FW-load showed higher vertical forces., Conclusions: MFL can be easily computed using a logarithmic model between the mean angular acceleration and moment of inertia to characterize the maximum theoretical loading intensity in the flywheel squat.

Pilonidal disease (PD) is a relatively common, benign but challenging condition of the natal cleft. This consensus statement was drawn up by a panel of surgeons, identified by the Italian Society of Colorectal Surgery (SICCR) as having a "special interest" in PD, with the aim of recommending the best therapeutic options according to currently available scientific evidence. A three-step modified-Delphi process was adopted, implying: (1) choice of the panelists; (2) development of a discussion outline and of target issues; and (3) a detailed systematic review of the current literature. The agreement/disagreement level was scored on a five-point Likert scale as follows: "A + : strongly agree; A-: agree; N: unsure/no opinion; D-: disagree; D + : strongly disagree. Each panelist contributed to the production of this manuscript, and the final recommendations were reviewed by the Clinical Practice Guidelines Committee., (© 2021. The Author(s).)

In this work, the melting line of calcium has been characterized both experimentally, using synchrotron X-ray diffraction in laser-heated diamond-anvil cells, and theoretically, using first-principles calculations. In the investigated pressure and temperature range (pressure between 10 and 40 GPa and temperature between 300 and 3000 K) it was possible to observe the face-centred phase of calcium and to confirm (and characterize for the first time at these conditions) the presence of the body-centred cubic and the simple cubic phase of calcium. The melting points obtained with the two techniques are in excellent agreement. Furthermore, the present results agree with the only existing melting line of calcium obtained in laser-heated diamond anvil cells, using the speckle method as melting detection technique. They also confirm a flat slope of the melting line in the pressure range between 10 and 30 GPa. The flat melting curve is associated with the presence of the solid high-temperature body-centered cubic phase of calcium and to a small volume change between this phase and the liquid at melting. Reasons for the stabilization of the body-centered face at high-temperature conditions will be discussed., (© 2021. The Author(s).)

Purpose: This study aimed to analyze mechanical performance and mechanical losses across different sets and repetitions of unilateral leg extensions under flywheel loading conditions., Methods: In a cross-over design, 23 physically active participants executed 3 sets of 30 repetitions using two different loads. Angular speed, angular acceleration and power were monitored, and mean and peak values of these variables were calculated for each set of repetitions. We analyzed time-course differences every five repetitions (described as 'clusters'). Differences in the mechanical profile for Load by Set and in the mechanical losses for Load by Set by Cluster repetitions were analyzed using an ANOVA repeated measures test. A Principal Components (PC) analysis was also conducted., Results: Only peak acceleration showed a significant Set by Load interaction (p = 0.006) in mechanical performance. At the intra-set level, all consecutive clusters showed a significant decrement in all variables, but with different magnitudes (speed < acceleration < power). Although all variables showed significant Set by Cluster and Load by Cluster interactions, only the acceleration variables showed a significant Set by Load interaction (p < 0.05). All the variables showed a single PC. Higher fatigue was found around the concentric peak for each variable., Conclusions: The most sensitive variable for detecting fatigue using real-time feedback seems to be the angular acceleration of the flywheel. Peak acceleration can be used to monitor training workload and training volume in real time in leg extension exercises using flywheel training devices., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The possibility of depositing precisely mass-selected Ag clusters (Ag 1 , Ag 3 , and Ag 7 ) on Ru(0001) was instrumental in determining the importance of the in-plane coordination number (CN) and allowed us to establish a linear dependence of the Ag 3d 5/2 core-level shift on CN. The fast cluster surface diffusion at room temperature, caused by the low interaction between silver and ruthenium, leads to the formation of islands with a low degree of ordering, as evidenced by the high density of low-coordinated atomic configurations, in particular CN = 4 and 5. On the contrary, islands formed upon Ag 7 deposition show a higher density of atoms with CN = 6, thus indicating the formation of islands with a close-packed atomic arrangement. This combined experimental and theoretical approach, when applied to clusters of different elements, offers the perspective to reveal nonequivalent local configurations in two-dimensional (2D) materials grown using different building blocks, with potential implications in understanding electronic and reactivity properties at the atomic level., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)

In this work, we characterize the adsorption of pentacene molecules on Ir(111) and their behaviour as a function of temperature. While room temperature adsorption preserves the molecular structure of the five benzene rings and the bonds between carbon and hydrogen atoms, we find that complete C-H molecular break up takes place between 450 K and 550 K, eventually resulting in the formation of small graphene islands at temperatures larger than 800 K. Most importantly a reversible temperature-induced dehydrogenation process is found when the system is annealed/cooled in a hydrogen atmosphere with a pressure higher than 5 × 10 -7 mbar. This novel process could have interesting implications for the synthesis of larger acenes and for the manipulation of graphene nanoribbon properties., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Introduction: Various pain management strategies for patients undergoing open excisional hemorrhoidectomy have been proposed, yet postoperative pain remains a frequent complaint., Objective: To determine whether mesoglycan (30 mg two vials i.m. once/day for the first 5 days postoperative, followed by 50 mg 1 oral tablet twice/day for 30 days) would reduce the edema of the mucocutaneous bridges and thus improve postoperative pain symptoms., Patients and Methods: For this prospective observational multicenter study, 101 patients undergoing excisional diathermy hemorrhoidectomy for III-IV degree hemorrhoidal disease were enrolled at 5 colorectal referral centers. Patients were assigned to receive either mesoglycan (study group SG) or a recommended oral dose of ketorolac tromethamine of 10 mg every 4-6 hours, not exceeding 40 mg per day and not exceeding 5 postoperative days according to the indications for short-term management of moderate/severe acute postoperative pain, plus stool softeners (control group CG)., Results: Postoperative thrombosis (SG 1/48 versus CG 5/45) ( p < 0.001) and pain after rectal examination ( p < 0.001) were significantly reduced at 7-10 days after surgery in the mesoglycan-treated group, permitting a faster return to work ( p < 0.001); however, in the same group, the incidence of postoperative bleeding, considered relevant when needing a readmission or an unexpected outpatient visit, was higher, possibly owing to the drug's antithrombotic properties., Conclusions: The administration of mesoglycan after an open diathermy excisional hemorrhoidectomy can reduce postoperative thrombosis and pain at 7-10 days after surgery, permitting a faster return to normal activities.

Background: The bulk of research on motherhood has focused on perinatal depression, largely overlooking indicators of women's positive mental health which can likewise have pervasive consequences on family functioning., Objective: The aim of the present study was to address this issue by exploring the impact of parity and childbirth on both women's perinatal depression and psychological well-being., Methods: A convenience sample of 81 women was followed during pregnancy (Time 1) and postpartum (Time 2). At both times, participants completed the Edinburgh Depression Scale and the Psychological Well-being Scales, measuring perceived autonomy, environmental mastery, personal growth, positive relations, purpose in life, and self-acceptance., Results: Significant negative correlations were observed between depression and psychological well-being dimensions. ANCOVA and mixed ANOVA analyses showed that depression levels did not differ between primiparous and multiparous women, or between pre- and postpartum assessments. By contrast, after childbirth, primiparous women reported higher values of environmental mastery and self-acceptance than multiparous women. In addition, levels of self-acceptance and personal growth increased from pregnancy to postpartum among primiparous women, while no differences were detected over time in the scores of all the psychological well-being dimensions among multiparous women., Conclusions: This study highlighted some dimensions of positive psychological functioning that specifically contribute to women's well-being in the transition to motherhood, and their different relevance for primiparous and multiparous mothers. Future trials are needed to integrate this information in tailored intervention for the promotion of mothers' complete mental health.

The purpose of this study was to analyse the raw lifting speed collected during four different resistance training exercises to assess the optimal sampling frequency. Eight physically active participants performed sets of Squat Jumps, Countermovement Jumps, Squats and Bench Presses at a maximal lifting speed. A linear encoder was used to measure the instantaneous speed at a 200 Hz sampling rate. Subsequently, the power spectrum of the signal was computed by evaluating its Discrete Fourier Transform. The sampling frequency needed to reconstruct the signals with an error of less than 0.1% was f 99.9  = 11.615 ± 2.680 Hz for the exercise exhibiting the largest bandwidth, with the absolute highest individual value being 17.467 Hz. There was no difference between sets in any of the exercises. Using the closest integer sampling frequency value (25 Hz) yielded a reconstruction of the signal up to 99.975 ± 0.025% of its total in the worst case. In conclusion, a sampling rate of 25 Hz or above is more than adequate to record raw speed data and compute power during resistance training exercises, even under the most extreme circumstances during explosive exercises. Higher sampling frequencies provide no increase in the recording precision and may instead have adverse effects on the overall data quality.

Aim: Many different surgical techniques have been reported for the surgical treatment of full-thickness external rectal prolapse. Perianal stapled prolapse resection (PSP) is a relatively newly reported technique for full thickness external rectal prolapse. The aim of this prospective multicentre study was to evaluate the results of this procedure., Method: Consecutive patients who underwent a PSP resection for full-thickness external rectal prolapse at five centres were recruited to the study. Median operating time, hospital stay, complications, recurrence and functional results according to the Wexner Incontinence Scale and obstructive defaecation syndrome score were recorded., Results: There were 27 patients treated by PSP. The median Wexner incontinence score improved from 10 presurgery to 5 after surgery (P < 0.001); the median obstructed defaecation syndrome score improved from 12 presurgery to 5 (range 4-10) after surgery (P < 0.001). A laparoscopically assisted procedure was performed in three patients (11.1%). The median number of cartridges used was six (range four to nine). The median operating time was 48 min. Early complications occurred in six patients (22.2%) and late complications in two (7.4%). The median length of hospital stay was 5 days. The recurrence rate at a median follow-up of 30.3 months was 14.8%., Conclusion: PSP appears to be an easy, fast and safe procedure. Early functional results are good. The recurrence rate compares favourably with other perineal procedures like the Delorme or the Altemeier operations. Long-term functional results need to be investigated further., (Colorectal Disease © 2016 The Association of Coloproctology of Great Britain and Ireland.)

The atomistic understanding of the dissociation mechanisms for large molecules adsorbed on surfaces is still a challenge in heterogeneous catalysis. This is especially true for polycyclic aromatic hydrocarbons, which represent an important class of organic compounds used to produce novel graphene-based architectures. Here, we show that coronene molecules adsorbed on Ir(111) undergo major conformational changes during dissociation. They first tilt upward with respect to the surface, still keeping their planar configuration, and subsequently experience a rotation, which changes the molecular axis orientation. Upon lifting, the internal C-C strain is initially relieved; as the dehydrogenation proceeds, the molecules experience a progressive increase in the average interatomic distance and gradually settle to form dome-shaped nanographene flakes. Our results provide important insight into the complex mechanism of molecular breakup, which could have implications in the synthesis of new carbon-based nanostructured materials.

We report on the temperature dependence of the electrical resistivity of solid iron at high pressure, up to and including conditions likely to be found at the centre of the Earth. We have extended some of the calculations of the resistivities of pure solid iron we recently performed at Earth's core conditions (Pozzo et al. in Earth Planet Sci Lett 393:159-164, 2014) to lower temperature. We show that at low temperature the resistivity increases linearly with temperature, and saturates at high temperature. This saturation effect is well known as the Mott-Ioffe-Regel limit in metals, but has been largely ignored to estimate the resistivity of iron at Earth's core conditions. Recent experiments (Gomi et al. in Phys Earth Planet Int 224:88-103, 2013) coupled new high pressure data and saturation to predict the resitivity of iron and iron alloys at Earth's core conditions, and reported values up to three times lower than previous estimates, confirming recent first principles calculations (de Koker et al. in Proc Natl Acad Sci 109:4070-4073, 2012; Pozzo et al. in Nature 485:355-358, 2012, Phys Rev B 87:014110-10, 2013, Earth Planet Sci Lett 393:159-164, 2014; Davies et al. in Nat Geosci 8:678-685, 2015). The present results support the saturation effect idea.

Purpose: To analyze the effect of an eccentric-overload training program (ie, half-squat and leg-curl exercises using flywheel ergometers) with individualized load on muscle-injury incidence and severity and performance in junior elite soccer players., Methods: Thirty-six young players (U-17 to U-19) were recruited and assigned to an experimental (EXP) or control group (CON). The training program consisted of 1 or 2 sessions/wk (3-6 sets with 6 repetitions) during 10 wk. The outcome measured included muscle injury (incidence per 1000 h of exposure and injury severity) and performance tests (countermovement jump [CMJ], 10-m and 20-m sprint test)., Results: Between-groups results showed a likely (ES: 0.94) lower number of days of absence per injury and a possible decrement of incidence per 1000 h of match play in EXP than in CON. Regarding muscle performance, a substantial better improvement (likely to very likely) was found in 20-m sprint time (ES: 0.37), 10-m flying-sprint time (ES: 0.77), and CMJ (ES: 0.79) for EXP than for CON. Within-group analysis showed an unclear effect in each variable in CON. Conversely, substantial improvements were obtained in CMJ (ES: 0.58), 20-m sprint time (ES: 0.32), 10-m flying-sprint time (ES: 0.95), and injury severity (ES: 0.59) in EXP. Furthermore, a possible decrement in total injury incidence was also reported in EXP., Conclusions: The eccentric-based program led to a reduction in muscle-injury incidence and severity and showed improvements in common soccer tasks such as jumping ability and linear-sprinting speed.

Background: Astronauts are required to perform both resistance and aerobic exercise while in orbit. This study assessed the aerobic energy yield and related physiological measurements using a nongravity dependent flywheel device designed for both resistance and aerobic exercise (RAD) in space., Methods: Eight physically active men and women performed all-out rowing on the RAD. For comparison, exercise was also carried out employing a commercially available rowing ergometer (C2)., Results: Peak oxygen uptake during exercise using RAD and C2 averaged 3.11 +/- 0.49 and 3.18 +/- 0.50 L x min(-1), respectively. Similarly, peak plasma lactate concentration (9.6 vs. 11.2 mmol x L(-1)), heart rate (183 vs. 184 bpm), and rate of perceived exertion (15.8 vs. 16.0) were comparable across exercise using the two devices., Discussion: Collectively, the results suggest that this novel exercise modality offers cardiovascular and metabolic responses, and thus aerobic exercise stimulus that is equally effective as that evoked by established technology for indoor rowing. Given the need for physiologically sound and highly effective exercise countermeasures that features small mass and envelope, and allows for resistance and aerobic exercise in a single apparatus, we believe this novel hardware should be considered for use in space.

The chemical and physical properties of nanoclusters largely depend on their sizes and shapes. This is partly due to finite size effects influencing the local electronic structure of the nanocluster atoms which are located on the nanofacets and on their edges. Here we present a thorough study on graphene-supported Rh nanocluster assemblies and their geometry-dependent electronic structure obtained by combining high-energy resolution core level photoelectron spectroscopy, scanning tunneling microscopy, and density functional theory. We demonstrate the possibility to finely control the morphology and the degree of structural order of Rh clusters grown in register with the template surface of graphene/Ir(111). By comparing measured and calculated core electron binding energies, we identify edge, facet, and bulk atoms of the nanoclusters. We describe how small interatomic distance changes occur while varying the nanocluster size, substantially modifying the properties of surface atoms. The properties of under-coordinated Rh atoms are discussed in view of their importance in heterogeneous catalysis and magnetism.

The Earth acts as a gigantic heat engine driven by the decay of radiogenic isotopes and slow cooling, which gives rise to plate tectonics, volcanoes and mountain building. Another key product is the geomagnetic field, generated in the liquid iron core by a dynamo running on heat released by cooling and freezing (as the solid inner core grows), and on chemical convection (due to light elements expelled from the liquid on freezing). The power supplied to the geodynamo, measured by the heat flux across the core-mantle boundary (CMB), places constraints on Earth's evolution. Estimates of CMB heat flux depend on properties of iron mixtures under the extreme pressure and temperature conditions in the core, most critically on the thermal and electrical conductivities. These quantities remain poorly known because of inherent experimental and theoretical difficulties. Here we use density functional theory to compute these conductivities in liquid iron mixtures at core conditions from first principles--unlike previous estimates, which relied on extrapolations. The mixtures of iron, oxygen, sulphur and silicon are taken from earlier work and fit the seismologically determined core density and inner-core boundary density jump. We find both conductivities to be two to three times higher than estimates in current use. The changes are so large that core thermal histories and power requirements need to be reassessed. New estimates indicate that the adiabatic heat flux is 15 to 16 terawatts at the CMB, higher than present estimates of CMB heat flux based on mantle convection; the top of the core must be thermally stratified and any convection in the upper core must be driven by chemical convection against the adverse thermal buoyancy or lateral variations in CMB heat flow. Power for the geodynamo is greatly restricted, and future models of mantle evolution will need to incorporate a high CMB heat flux and explain the recent formation of the inner core.