Physical Hypothesis Research Articles

Revisiting ENSO/Indian Ocean Dipole phase relationships

AbstractHere we show that the characteristics of the Indian Ocean Dipole (IOD), such as its power spectrum and phase relationship with the El Niño–Southern Oscillation (ENSO), can be succinctly explained by ENSO combination mode (C‐mode) wind and heat flux forcing together with a seasonal modulation of the air/sea coupled Indian Ocean (IO) Bjerknes feedback. This model explains the observed high‐frequency near‐annual IOD variability in terms of deterministic ENSO/annual cycle interactions. ENSO‐independent IOD events can be understood as a seasonally modulated ocean response to white noise atmospheric forcing. Under this new physical null hypothesis framework, IOD predictability is determined by both ENSO predictability and the ENSO signal‐to‐noise ratio. We further emphasize that lead/lag correlations between different climate variables are easily misinterpreted when not accounting properly for the seasonal modulation of the underlying climate phenomena.

Orbit-spin coupling and the interannual variability of global-scale dust storm occurrence on Mars

A new physical hypothesis predicts that a weak coupling of the orbital and rotational motions of extended bodies may give rise to a modulation of circulatory flows within their atmospheres. Driven cycles of intensification and relaxation of large-scale circulatory flows are predicted, with the phasing of these changes linked directly to the rate of change of the orbital angular momentum, dL/dt, with respect to inertial frames. We test the hypothesis that global-scale dust storms (GDS) on Mars may occur when periods of circulatory intensification (associated with positive and negative extrema of the dL/dt waveform) coincide with the southern summer dust storm season on Mars. The orbit-spin coupling hypothesis additionally predicts that the intervening ‘transitional’ periods, which are characterized by the disappearance and subsequent sign change of dL/dt, may be unfavorable for the occurrence of GDS, when they occur during the southern summer dust storm season. These hypotheses are strongly supported by comparisons between calculated dynamical time series of dL/dt and historic observations. All of the nine known global-scale dust storms on Mars took place during Mars years when circulatory intensification during the dust storm season is ‘retrodicted’ under the orbit-spin coupling hypothesis. None of the historic global-scale dust storms of our catalog occurred during transitional intervals. Orbit-spin coupling appears to play an important role in the excitation of the interannual variability of the atmospheric circulation of Mars.

Does gastric bypass surgery change body weight set point?

The relatively stable body weight during adulthood is attributed to a homeostatic regulatory mechanism residing in the brain which uses feedback from the body to control energy intake and expenditure. This mechanism guarantees that if perturbed up or down by design, body weight will return to pre-perturbation levels, defined as the defended level or set point. The fact that weight re-gain is common after dieting suggests that obese subjects defend a higher level of body weight. Thus, the set point for body weight is flexible and likely determined by the complex interaction of genetic, epigenetic and environmental factors. Unlike dieting, bariatric surgery does a much better job in producing sustained suppression of food intake and body weight, and an intensive search for the underlying mechanisms has started. Although one explanation for this lasting effect of particularly Roux-en-Y gastric bypass surgery (RYGB) is simple physical restriction due to the invasive surgery, a more exciting explanation is that the surgery physiologically reprograms the body weight defense mechanism. In this non-systematic review, we present behavioral evidence from our own and other studies that defended body weight is lowered after RYGB and sleeve gastrectomy. After these surgeries, rodents return to their preferred lower body weight if over- or underfed for a period of time, and the ability to drastically increase food intake during the anabolic phase strongly argues against the physical restriction hypothesis. However, the underlying mechanisms remain obscure. Although the mechanism involves central leptin and melanocortin signaling pathways, other peripheral signals such as gut hormones and their neural effector pathways likely contribute. Future research using both targeted and non-targeted 'omics' techniques in both humans and rodents as well as modern, genetically targeted, neuronal manipulation techniques in rodents will be necessary.

Water mass transformation by cabbeling and thermobaricity

AbstractWater mass transformation is an important process for the global ocean circulation. Nonlinearities in the equation of state of seawater lead to water mass transformation due to cabbeling and thermobaricity. Here the contribution of cabbeling and thermobaricity to water mass transformation is calculated in a Neutral Density framework, using temperature gradients derived from observationally based gridded climatologies and observationally based estimates of the spatially varying eddy diffusivities. It is shown that cabbeling and thermobaricity play a significant role in the water mass transformation budget, with cabbeling having a particularly important role in the formation of Antarctic Intermediate Water and Antarctic Bottom Water. A physical hypothesis is presented which explains why cabbeling is important for Antarctic Intermediate Water formation. It is shown that spatially varying estimates of eddy diffusivities are essential to correctly quantify the role of cabbeling to the formation of Antarctic Intermediate Water.

Experimental results of radiation-driven, layered deuterium-tritium implosions with adiabat-shaped drives at the National Ignition Facility

Radiation-driven, layered deuterium-tritium (DT) implosions were carried out using 3-shock and 4-shock “adiabat-shaped” drives and plastic ablators on the National Ignition Facility (NIF) [E. M. Campbell et al., AIP Conf. Proc. 429, 3 (1998)]. The purpose of these shots was to gain further understanding on the relative performance of the low-foot implosions of the National Ignition Campaign [M. J. Edwards et al., Phys. Plasmas 20, 070501 (2013)] versus the subsequent high-foot implosions [T. Döppner et al., Phys. Rev. Lett. 115, 055001 (2015)]. The neutron yield performance in the experiment with the 4-shock adiabat-shaped drive was improved by factors ∼3 to ∼10, compared to five companion low-foot shots despite large low-mode asymmetries of DT fuel, while measured compression was similar to its low-foot companions. This indicated that the dominant degradation source for low-foot implosions was ablation-front instability growth, since adiabat shaping significantly stabilized this growth. For the experiment with the low-power 3-shock adiabat-shaped drive, the DT fuel compression was significantly increased, by ∼25% to ∼36%, compared to its companion high-foot implosions. The neutron yield increased by ∼20%, lower than the increase of ∼50% estimated from one-dimensional scaling, suggesting the importance of residual instabilities and asymmetries. For the experiment with the high-power, 3-shock adiabat-shaped drive, the DT fuel compression was slightly increased by ∼14% compared to its companion high-foot experiments. However, the compression was reduced compared to the lower-power 3-shock adiabat-shaped drive, correlated with the increase of hot electrons that hypothetically can be responsible for reduced compression in high-power adiabat-shaped experiments as well as in high-foot experiments. The total neutron yield in the high-power 3-shock adiabat-shaped shot N150416 was 8.5 × 1015 ± 0.2 × 1015, with the fuel areal density of 0.90 ± 0.07 g/cm2, corresponding to the ignition threshold factor parameter IFTX (calculated without alpha heating) of 0.34 ± 0.03 and the yield amplification due to the alpha heating of 2.4 ± 0.2. The performance parameters were among the highest of all shots on NIF and the closest to ignition at this time, based on the IFTX metric. The follow-up experiments were proposed to continue testing physics hypotheses, to measure implosion reproducibility, and to improve quantitative understanding on present implosion results.

Erratum: On the use of composite analyses to form physical hypotheses: An example from heat wave - SST associations.

Scientific Reports 6: Article number: 29599; published online: 14 July 2016; updated: 24 August 2016 This Article contains an error in the legend of Table 1. “Results are computed for the entire 3150 days in DJF (black values) and for the 25 HW days selected in DJF (bold italic) during 1979–2014,” should read:

On the use of composite analyses to form physical hypotheses: An example from heat wave - SST associations.

This paper highlights some caveats in using composite analyses to form physical hypotheses on the associations between environmental variables. This is illustrated using a specific example, namely the apparent links between heat waves (HWs) and sea surface temperatures (SSTs). In this case study, a composite analysis is performed to show the large-scale and regional SST conditions observed during summer HWs in Perth, southwest Australia. Composite results initially point to the importance of the subtropical South Indian Ocean, where physically coherent SST dipole anomalies appear to form a necessary condition for HWs to develop across southwest Australia. However, sensitivity tests based on pattern correlation analyses indicate that the vast majority of days when the identified SST pattern appears are overwhelmingly not associated with observed HWs, which suggests that this is definitely not a sufficient condition for HW development. Very similar findings are obtained from the analyses of 15 coupled climate model simulations. The results presented here have pertinent implications and applications for other climate case studies, and highlight the importance of applying comprehensive statistical approaches before making physical inferences on apparent climate associations.

Large angular scale CMB anisotropy from an excited initial mode**Supported by the Islamic Azad University, Rasht Branch, Rasht, Iran

According to inflationary cosmology, the CMB anisotropy gives an opportunity to test predictions of new physics hypotheses. The initial state of quantum fluctuations is one of the important options at high energy scale, as it can affect observables such as the CMB power spectrum. In this study a quasi-de Sitter inflationary background with approximate de Sitter mode function built over the Bunch-Davies mode is applied to investigate the scale-dependency of the CMB anisotropy. The recent Planck constraint on spectral index motivated us to examine the effect of a new excited mode function (instead of pure de Sitter mode) on the CMB anisotropy at large angular scales. In so doing, it is found that the angular scale-invariance in the CMB temperature fluctuations is broken and in the limit ℓ < 200 a tiny deviation appears. Also, it is shown that the power spectrum of CMB anisotropy is dependent on a free parameter with mass dimension H << M* < Mp and on the slow-roll parameter ϵ.

The Trans-Contextual Model of Autonomous Motivation in Education: Conceptual and Empirical Issues and Meta-Analysis.

The trans-contextual model outlines the processes by which autonomous motivation toward activities in a physical education context predicts autonomous motivation toward physical activity outside of school, and beliefs about, intentions toward, and actual engagement in, out-of-school physical activity. In the present article, we clarify the fundamental propositions of the model and resolve some outstanding conceptual issues, including its generalizability across multiple educational domains, criteria for its rejection or failed replication, the role of belief-based antecedents of intentions, and the causal ordering of its constructs. We also evaluate the consistency of model relationships in previous tests of the model using path-analytic meta-analysis. The analysis supported model hypotheses but identified substantial heterogeneity in the hypothesized relationships across studies unattributed to sampling and measurement error. Based on our meta-analysis, future research needs to provide further replications of the model in diverse educational settings beyond physical education and test model hypotheses using experimental methods.

Development of a Short Version of MSQOL-54 Using Factor Analysis and Item Response Theory.

BackgroundThe Multiple Sclerosis Quality of Life-54 (MSQOL-54, 52 items grouped in 12 subscales plus two single items) is the most used MS specific health related quality of life inventory.ObjectiveTo develop a shortened version of the MSQOL-54.MethodsMSQOL-54 dimensionality and metric properties were investigated by confirmatory factor analysis (CFA) and Rasch modelling (Partial Credit Model, PCM) on MSQOL-54s completed by 473 MS patients. Their mean age was 41 years, 65% were women, and median Expanded Disability Status Scale (EDSS) score was 2.0 (range 0–9.5). Differential item functioning (DIF) was evaluated for gender, age and EDSS. Dimensionality of the resulting short version was assessed by exploratory factor analysis (EFA) and CFA. Cognitive debriefing of the short instrument (vs. the original) was then performed on 12 MS patients.ResultsCFA of MSQOL-54 subscales showed that the data fitted the overall model well. Two subscales (Role Limitations—Physical, Role Limitations—Emotional) did not fit the PCM, and were removed; two other subscales (Health Perceptions, Social Function) did not fit the model, but were retained as single items. Sexual Satisfaction (single-item subscale) was also removed. The resulting MSQOL-29 consisted of 25 items grouped in 7 subscales, plus 4 single items. PCM fit statistics were within the acceptability range for all MSQOL-29 items except one which had significant DIF by age. EFA and CFA indicated adequate fit to the original two-factor (Physical and Mental Health Composites) hypothesis. Cognitive debriefing confirmed that MSQOL-29 was acceptable and had lost no key items.ConclusionsThe proposed MSQOL-29 is 50% shorter than MSQOL-54, yet preserves key quality of life dimensions. Prospective validation on a large, independent MS patient sample is ongoing.

Modal wavenumber estimation using a Bayesian compressed sensing algorithm

In shallow water, low-frequency acoustic propagation is described by modal theory. In this context, the environment acts as a dispersive waveguide, and the geoacoustic properties of the seabed can be inferred from the modal wavenumbers. When considering horizontal aperture (using a horizontal array or a towed source), wavenumber estimation is a well-known problem, equivalent to spectral analysis. In this paper, wavenumber estimation is revisited using Compressed Sensing (CS). Our method benefits from two strong physical hypotheses. Only a few modes are propagating so that the wavenumber spectrum is sparse. Moreover, if the source is broadband, the wavenumbers can be related from one frequency to the next using a general dispersion relationship. Our method resorts to a state-of-the-art Bayesian algorithm exploiting a Bernoulli-Gaussian model. The latter, well-suited to the sparse representations, makes possible a natural integration of the prior dispersion information through a wise choice of the Bernoulli parameters. The whole methodology is assessed on simulated data and successfully applied on marine data.

Evolution physical intelligent guiding principle

Ordinary physics being unable to specify an intelligent guiding principle to account for the apparent life’s intelligent design, some of the intelligent design movement advocates propose a metaphysical intelligent designer. In this regard, although intelligent design movement starts from a valid scientific premise, it ends up with a metaphysical inference that cannot be empirically falsified. Thus, it undermines its scientific credibility. Based on quantum information biology (QIB) which is a generalized physics hypothesis, we demonstrate that biological evolution is subject to a physical intelligent guiding principle (PIGP). Generalized physics (QIB) is a set of physical properties and laws that distinguish life from nonlife, irreducible to ordinary physics, and admit limiting transition to quantum mechanics. In other words, biology, or some aspects of it, is generalized physics. According to the PIGP, a species’ increase in bio-complexity, phylogenetically, measured in terms of Jorgensen’s eco-exergy density is a function of its bio-intelligence. Bio-intelligence has the dimensions of action, information and time; it is the capacity to generate bio-complexity and represents evolution target criterion. The PIGP does not clash with Darwinian evolution basic mechanism, random mutational changes and natural selection. Because natural selection selects beneficial mutations and beneficial mutations are those which satisfy the criteria of bio-intelligence, they are not random. Bio-intelligence is the origin of human intelligence, i.e., “The nature of intelligence is nature’s intelligence.”

Theoretical model for temperature prediction in Incremental Sheet Forming – Experimental validation

Temperature prediction is a fundamental aspect of material workability and microstructural evolution. The need to predict temperatures is particularly important for processes where temperature is not a fixed a priori as well as in processes where temperature is affected by multiple variables. Incremental Sheet Forming (ISF) is one such process and it is considered particularly relevant in this discussion because the process parameters chosen are the ones that most affect temperature variation in the forming area. The aim of this paper is to define a temperature prediction model based on mathematical formulae. This model can be used to predict the temperature of the material during the forming phase using different process parameters. Two lightweight alloys with different thermal properties were studied. An aluminium and a titanium were chosen because their differences guarantee the generality of the model. Experimental tests were performed to calibrate and validate the quality of the proposed model. An iterative algorithm was implemented to predict the temperature trend of the sheet. Satisfactory results have been found confirming the physical hypothesis made to justify the phenomenon of temperature increase in ISF as well as the reliability of temperature prediction during the process.

Truths and misconceptions in the ore comminution

Inventions and now widely applied machines for ore comminution dated back to the second half of the 19th century. For the past 150 years, much theoretical knowledge was accumulated in the field of physics the solid bodies, physics of fracture, the theory of shock, etc., but they did not significantly affect the development of machines and technologies of comminution. Their development had a high­lighted the empirical flow in the direction of increasing the unit sizes and capacities, while the main deformation mechanisms and technological principles remained unchanged. Development on practical experiences and insufficient physical justified hypothesis of the solid state physics inevitably had to result in some misconceptions that, despite recent theoretical knowledge and proven facts, continue to exist in practice. This paper just wants to point out some of these misconceptions.

Determination of the wingsnap sonation mechanism of the golden-collared manakin (Manacus vitellinus).

Male golden-collared manakins (Manacus vitellinus), small suboscine passeriform birds of Panamanian forests, communicate acoustically using a variety of non-vocal sonations. The most prominent sonations are single or multiple intense 'wingsnaps' with a dominant acoustic frequency around 5 kHz. Several hypotheses have been proposed addressing the source of the sound, ranging from purely aerodynamic origins (due to a rapid jet of air formed by the wings or by a 'whiplike' motion) to purely structural origins (such as physical contact of the wings), but without definitive assessment. Using anatomical analysis as well as high-speed video and synchronized audio recordings, we show that compared with related species, M. vitellinus radii are morphologically unique and confirm that they collide over the back of the bird at the moment (±1 ms) the wingsnap is produced. Using aeroacoustic theory, we quantitatively estimate the acoustic signatures from several sonation mechanisms. We conclude that only the physical contact hypothesis, wherein the wing collisions create the sound, is consistent with the measured sonation.

Letter to the Editor: End-of-life experience case study and a proposed quantum physics hypothesis.

Letter to the Editor: End-of-life experience case study and a proposed quantum physics hypothesis.

A physically motivated model for filled elastomers including strain rate and amplitude dependency in finite viscoelasticity

The Dynamic Flocculation Model (DFM) is a micro-structure based model of rubber reinforcement which is developed on a physical framework to describe the non-linear and inelastic mechanical behavior of filled elastomers (Klüppel, 2003). This one-dimensional material law has been implemented into the finite element code using the concept of representative directions (Freund et al., 2011), which allows the generalization of one-dimensional model to compute three dimensional stress-strain states. The model shows very good agreement with the standard quasi-static multi-hysteresis tests on CB-filled elastomers like NR, SBR or EPDM among others. An extension of this model to include time dependent effects allows to consider the filler induced dynamic response such as strain rate dependency, amplitude dependency and stress relaxation. The physical hypothesis of characterizing the filler clusters as time-dependent parameters is described in Juhre et al. (2013). In this work contribution the quasi-static DFM model was extended to include the time-dependent effects using first-order differential relaxation equation which evolves as a function of time. Subsequently, the corresponding parameters were identified through curve fitting and the model was further validated against associating experiments. The influence of each parameter on the course of change in material behavior has been investigated. The major advantage of the model is its physically meaningful parameters and the ability to reproduce the material response at different loading rates under arbitrary deformation using the single parameter set for each rubber compound.

The hydrodynamic basis of the vacuum cleaner effect in continuous-flow PCNL instruments: an empiric approach and mathematical model.

Passive removal of stone fragments in the irrigation stream is one of the characteristics in continuous-flow PCNL instruments. So far the physical principle of this so-called vacuum cleaner effect has not been fully understood yet. The aim of the study was to empirically prove the existence of the vacuum cleaner effect and to develop a physical hypothesis and generate a mathematical model for this phenomenon. In an empiric approach, common low-pressure PCNL instruments and conventional PCNL sheaths were tested using an in vitro model. Flow characteristics were visualized by coloring of irrigation fluid. Influence of irrigation pressure, sheath diameter, sheath design, nephroscope design and position of the nephroscope was assessed. Experiments were digitally recorded for further slow-motion analysis to deduce a physical model. In each tested nephroscope design, we could observe the vacuum cleaner effect. Increase in irrigation pressure and reduction in cross section of sheath sustained the effect. Slow-motion analysis of colored flow revealed a synergism of two effects causing suction and transportation of the stone. For the first time, our model showed a flow reversal in the sheath as an integral part of the origin of the stone transportation during vacuum cleaner effect. The application of Bernoulli's equation provided the explanation of these effects and confirmed our experimental results. We widen the understanding of PCNL with a conclusive physical model, which explains fluid mechanics of the vacuum cleaner effect.

Possibility for the Conjugated Use of Photodynamic Therapy and Electrosurgical Devices.

Because tissue optics limits the treated volume during anti-tumor Photodynamic Therapy (PDT), its conjugation with prior tissue debulking has been suggested clinically. In this context, the conjugation of radiofrequency ablation and PDT has already been demonstrated. However, the basic principles that enable the success of these protocols have not been discussed. This proof-of-principle study analyzes the possibility of conjugating electrosurgery (ES) and PDT, analyzing different sequences of photosensitizer (PS) administration in an animal model. The animals were distributed over five groups: ES, PS+Light, PS+ES, ES+PS+Light and PS+ES+Light. The PS Photogem was administered systemically. An electrosurgical unit (480 kHz) was used to remove a portion of the liver, leaving a plane surface for PDT illumination (630 nm, 150 J/cm²). Fluorescence was collected during the stages of the experiment to monitor the PS accumulation. After 30 hours, histological processing was performed. The fluorescence spectra revealed strong Photogem emission in both administration sequences (ES+PS; PS+ES), and little PS bleach after ES was observed. The maximum necrosis depth was observed for the PS+ES+Light group—(716 ± 75) μm—higher than its respective control group (160 ± 28) μm, proving successful conjugation. Histological features from ES and PDT on both conjugation sequences were observed. Pre-photosensitized tissue presented decreased ES-related thermal damage. A simple physical hypothesis, based on the Joule effect and the tissue electrical conductivity, was proposed to support these findings. In conclusion, the results successfully demonstrated the possibility of conjugating ES and PDT in a single protocol.

What is the mechanism behind biological ferroelectricity?

Biological tissues are soft, amorphous and often appear to possess a high degree of material symmetry. This would appear to preclude a phenomenon like ferroelectricity which, in the world of hard materials, only occurs in selected crystalline materials that are non-centrosymmetric. Recent experiments, however, indicate the presence of ferroelectricity in soft biological entities such as the protein elastin—a large biopolymer found in the extracellular domains of most tissues. In this letter, we present a model and an explanation for this intriguing observation. Based on a very simple physical hypothesis, we develop an analytical statistical mechanics model that, coupled with insights from molecular dynamics, provides a plausible mechanism underpinning biological ferroelectricity. Furthermore, we predict for the first time, piezoelectric properties of tropoelastin, a precursor/monomer of elastin—properties that are not easily obtained from experiments. Specifically we find that the piezoelectric constant of tropoelastin is larger than any known polymer.