The clinical course of low back pain: a meta-analysis comparing outcomes in randomised clinical trials (RCTs) and observational studies.

BACKGROUND: Evidence suggests that the course of low back pain (LBP) symptoms in randomised clinical trials (RCTs) follows a pattern of large improvement regardless of the type of treatment. A similar pattern was independently observed in observational studies. However, there is an assumption that the clinical course of symptoms is particularly influenced in RCTs by mere participation in the trials. To test this assumption, the aim of our study was to compare the course of LBP in RCTs and observational studies. METHODS: Source of studies CENTRAL database for RCTs and MEDLINE, CINAHL, EMBASE and hand search of systematic reviews for cohort studies. Studies include individuals aged 18 or over, and concern non-specific LBP. Trials had to concern primary care treatments. Data were extracted on pain intensity. Meta-regression analysis was used to compare the pooled within-group change in pain in RCTs with that in cohort studies calculated as the standardised mean change (SMC). RESULTS: 70 RCTs and 19 cohort studies were included, out of 1134 and 653 identified respectively. LBP symptoms followed a similar course in RCTs and cohort studies: a rapid improvement in the first 6 weeks followed by a smaller further improvement until 52 weeks. There was no statistically significant difference in pooled SMC between RCTs and cohort studies at any time point:- 6 weeks: RCTs: SMC 1.0 (95% CI 0.9 to 1.0) and cohorts 1.2 (0.7to 1.7); 13 weeks: RCTs 1.2 (1.1 to 1.3) and cohorts 1.0 (0.8 to 1.3); 27 weeks: RCTs 1.1 (1.0 to 1.2) and cohorts 1.2 (0.8 to 1.7); 52 weeks: RCTs 0.9 (0.8 to 1.0) and cohorts 1.1 (0.8 to 1.6). CONCLUSIONS: The clinical course of LBP symptoms followed a pattern that was similar in RCTs and cohort observational studies. In addition to a shared 'natural history', enrolment of LBP patients in clinical studies is likely to provoke responses that reflect the nonspecific effects of seeking and receiving care, independent of the study design

Photography-based taxonomy is inadequate, unnecessary, and potentially harmful for biological sciences

The question whether taxonomic descriptions naming new animal species without type specimen(s) deposited in collections should be accepted for publication by scientific journals and allowed by the Code has already been discussed in Zootaxa (Dubois & Nemésio 2007; Donegan 2008, 2009; Nemésio 2009a–b; Dubois 2009; Gentile & Snell 2009; Minelli 2009; Cianferoni & Bartolozzi 2016; Amorim et al. 2016). This question was again raised in a letter supported by 35 signatories published in the journal Nature (Pape et al. 2016) on 15 September 2016. On 25 September 2016, the following rebuttal (strictly limited to 300 words as per the editorial rules of Nature) was submitted to Nature, which on 18 October 2016 refused to publish it. As we think this problem is a very important one for zoological taxonomy, this text is published here exactly as submitted to Nature, followed by the list of the 493 taxonomists and collection-based researchers who signed it in the short time span from 20 September to 6 October 2016

A Simple Ising-Like Model for Spin Conversion Including Molecular Vibrations

An Ising-type model for spin conversion, explicitly accounting for intramolecular vibrations has been studied. Each two level system is associated with p harmonic oscillators having two possible frequencies ωLS(i),ωHS(i). The major advantage of this model is that it provides an excellent agreement with both the conversion curve and calorimetric data, in particular the entropy change upon spin conversion. With the help of Arrhenius plots, the predictions of the model are accurately compared to the literature experimental data on the spin equilibruim curves. A very accurate Mössbauer investigation by Jacobi, Spiering and Gütlich, provides evidence for a small effect typical for vibrations. A novel example is given where the conversion curve is essentially monitored by vibrations; this originates from the extremely small value of the energy gap between HS and LS electrovibrational groundstates. However, in most cases, as a first approach, the low frequency approximation of the model can be used. Then the model reduces to a simple two-level model with additional degeneracies implicitely accounting for intramolecular vibrations

Flow modeling of a battery of industrial crude oil/gas separators using 113mIn tracer experiments

The objective of this work is to study the flow behavior of crude oil in a battery of industrial crude oil/gas separators in oil industry. The battery is composed of three separators operating at different pressures. The residence time distribution (RTD) of the crude oil has been determined by an impulse injection of 113mIn at the inlet of each separator and the concentration has been continuously recorded at the outlet. The real volume occupied by the crude oil has been determined by simple estimation of the first moments. The RTD of the crude oil has been simulated by a model composed of few mixing cells in series representing the effect of the deflector located at the entrance and a plug flow partly due to the high viscosity of the crude oil. The variation of the parameters of the model has been studied as a function of pressure conditions and they have been linked to the deposition of sediment. The tracer measurement in gas phase showed that this method can detect non-negligible malfunction but it is not sensitive enough to assume that the zero tolerance of oil concentration in gas phase requested by the exploitant is respected

Dilution Effects in a Spin Crossover System, Modelled in Terms of Direct and Indirect Intermolecular Interactions

We have studied by 57Fe Mössbauer spectroscopy and magnetic measurements the spin transition exhibited by the series: , consisting of a spin-crossover iron(II) system diluted in a high-spin cobalt(II) matrix. We performed Monte Carlo simulations of the thermal variation of the high-spin fraction, using a two-level Ising-type Hamiltonian. A good agreement with experiment is obtained by the introduction of an indirect interaction of the spin-crossover units via the non-spin crossover unit, the origin of which is discussed in steric terms

Dilution Effects in a Spin Crossover System, Modelled in Terms of Direct and Indirect Intermolecular Interactions

We have studied by $^{57}$Fe Mössbauer spectroscopy and magnetic measurements the spin transition exhibited by the series: , consisting of a spin-crossover iron(II) system diluted in a high-spin cobalt(II) matrix. We performed Monte Carlo simulations of the thermal variation of the high-spin fraction, using a two-level Ising-type Hamiltonian. A good agreement with experiment is obtained by the introduction of an indirect interaction of the spin-crossover units via the non-spin crossover unit, the origin of which is discussed in steric terms