Modelling of weak quantum measurements consistent with conservation laws

We discuss quantum mechanical detection models in the weak limit in the context of conservation laws of physical quantities. In particular, we analyze what kind of system–detector interaction can preserve the global conservation or the related symmetry, and how the final measurement on the detector affects the measured observable of the systems and its presumed conservation. It turns out that the order of noncommuting measurements results in observable differences on the level of third-order correlations functions.

Sympathetic and sensory nerve fiber function in multiple system atrophy and idiopathic Parkinson’s disease

Objective To explore small fiber somatosensory and sympathetic function in PD and MSA. Methods We recruited 20 PD patients (7 women, median age 65.5 years; IQR 54.75–70.0), 10 MSA patients (4 women; median age 68 years; IQR 66.25–74.0), and 10 healthy subjects (HC; 4 women, median age 68; IQR 59.0–71.0 years). Autonomic testing included forehead cooling, intradermal microdialysis of norepinephrine (NE; 10–5; 10–6; 10–7; and 10–8), and orthostatic hypotension (OH); somatosensory testing included quantitative sensory testing (QST) according to the protocol of the German Research Network on Neuropathic Pain (DFNS). Results OH occurred more frequently in PD (p = 0.018) and MSA (p = 0.002) compared to HC. Vasoconstriction responses were stronger in PD compared to MSA during forehead cooling (p = 0.044) and microdialysis of physiologically concentrated NE solutions (10–7; 10–8; p = 0.017). PD and MSA had impaired cold (PD: p < 0.01; MSA: p < 0.05) and warm detection thresholds (PD and MSA, both p < 0.05). The mechanical detection threshold was higher in PD (p < 0.01). Conversely, mechanical pain thresholds were decreased in PD and MSA (both p < 0.001), indicating mechanical hyperalgesia. Conclusion In contrast to MSA, we found evidence of peripheral adrenoreceptor hypersensitivity in PD, probably caused by peripheral sympathetic denervation. Sensory testing revealed peripheral neuropathy and central pain sensitization in PD and MSA. Jointly, our data demonstrate autonomic and somatosensory dysfunction in PD and MSA.

Changes of Somatosensory Phenotype in the Course of Disease in Osteoarthritis Patients

To investigate sensory changes, physical function (pF), quality of life (QoL) and pain intensity of patients with osteoarthritis (OA) in the natural course of disease, and patients undergoing total joint replacement therapy (TJR) 31 (20 females, mean age 64.6 ± 10.4 years), patients with OA were investigated with questionnaires and quantitative sensory testing (QST) in the area of referred pain at the thigh at baseline and follow-up 22–49 weeks later; changes were analyzed separately for patients with (n = 13) and without TJR (n = 18). In patients without TJR pain intensity, pF, QoL did not improve, and increased pain sensitivity to cold and a stronger loss of detection were observed. In patients after TJR, however, a reduction in mechanical pain sensitivity and allodynia occurred in accordance with a reduction of pain intensity and improvement of functionality while QoL did not improve. Additionally, an increased sensitivity to heat pain and a more pronounced loss of mechanical detection could be observed in this group. TJR seems to stop peripheral pain input leading to a reduction of pain intensity and central sensitization, but surgery-induced sensory changes such as peripheral sensitization and loss of detection occur. Furthermore, TJR has favorable effects on pain intensity and functionality but not QoL.

Oscillations in the near-field feeding current of a calanoid copepod are useful for particle sensing

Calanoid copepods are small crustaceans that constitute a major element of aquatic ecosystems. Key to their success is their feeding apparatus consisting of sensor-studded mouth appendages that are in constant motion. These appendages generate a feeding current to enhance the encounter probability with food items. Additionally, sensing enables the organism to determine the position and quality of food particles, and to alter the near-field flow to capture and manipulate the particles for ingestion or rejection. Here we observe a freely swimming copepod Leptodiaptomus sicilis in multiple perspectives together with suspended particles that allow us to analyse the flow field created by the animal. We observe a highly periodic motion of the mouth appendages that is mirrored in oscillations of nearby tracer particles. We propose that the phase shift between the fluid and the particle velocities is sufficient for mechanical detection of the particles entrained in the feeding current. Moreover, we propose that an immersed algal cell may benefit from the excitation by increased uptake of dissolved inorganic compounds.

Is in vivo reflectance confocal microscopy a useful assessment tool in chemotherapy-induced peripheral neuropathy (CIPN)?

e23088 Background: The lack of standardized diagnostic or assessment tools in CIPN pose an unmet need for objective and reliable measures. Advances in non-invasive, in vivo reflectance confocal microscopy (RCM) offer a painless method to identify markers of peripheral neuropathy such as loss of Meissner’s corpuscles (MC). This study aims to investigate the feasibility of RCM in CIPN by assessing MC density in healthy controls compared to cancer patients. Methods: RCM imaging (Vivascope 1500) was performed on the fingertip (digit V) to evaluate MC density in 45 healthy controls and 9 cancer patients prior to starting chemotherapy. Quantification was completed by two reviewers, one being blinded to achieve unbiased identification as the maximum MC count/6x6 mm image. Quantitative Sensory Testing (thermal and mechanical detection thresholds) along with the grooved pegboard test (sensorimotor function) were conducted for comparison with MC density. Spearman’s correlation coefficients were used to determine associations. Results: In healthy controls (25 females, 20 males; mean age 58.9, range 24-81 years), females exhibited a greater mean MC density compared with males (49.9 ± 7.1 MC vs 30.9 ± 4.2 MC; p = 0.03). Variances were observed across age range by decade (p < 0.0001). MC density was inversely correlated with mechanical detection (ρ = -0.51) and warm detection thresholds (ρ = -0.47) in contrast to cold pain threshold (ρ = 0.49). All correlations were significant (p < 0.01). Time to complete the grooved pegboard test correlated with MC density in the dominant hand (p = 0.02) and non-dominant hand (p < 0.01). Compared with age and gender matched controls, cancer patients had reduced MC density (22.0 ± 9.3 vs 35.4 ± 14.1; p = 0.03), mirroring deficits in cold detection threshold and the grooved pegboard test. Inter-rater reliability of MC density count showed an intraclass correlation of 0.96 (p < 0.0001). Conclusions: The findings from this study support the clinical utility of RCM in CIPN. Assessment of MC density using RCM may provide meaningful markers of sensory loss, sensorimotor function and an ability to detect possible subclinical deficits in patients at risk of CIPN prior to initiating chemotherapy.

Root density sensing allows pro-active modulation of shoot growth to avoid future resource limitation

ABSTRACTPlants use environmental cues to determine their optimal root and shoot growth. It is well known to gardeners and horticulturists alike that soil volume – most commonly in the form of pot size – strongly restricts plant growth, but the mechanisms by which this effect occurs remain unclear. Here, we show that shoot growth scales directly with soil volume, independently of the nutritional content of the soil, and that plants can become ‘volume restricted’ even in the presence of abundant resources. We show that plants can detect their soil volume as early as 3 weeks post germination, and that shoot growth restriction therefore constitutes a pro-active ‘decision’ by the plant to avoid resource limitation later in the life cycle. Shoot growth restriction is not directly linked to root growth restriction, and does not occur in response to the mechanical detection of the pot walls. Rather, we show that plants detect their soil volume by detecting the density of roots in the proximity of their root system. As such, volume restriction may be intimately connected with the mechanism by which plants sense and respond to the roots of other plants in the rhizosphere. Our work demonstrates the remarkable ability of plants to make pro-active decisions about their growth to ensure they can complete their cycle, and has important implications for agricultural practise regarding both nutrient use efficiency and yield.

Cranial parasympathetic activation induces autonomic symptoms but no cluster headache attacks

Background Low frequency (LF) stimulation of the sphenopalatine ganglion (SPG) may increase parasympathetic outflow and provoke cluster headache (CH) attacks in CH patients implanted with an SPG neurostimulator. Methods In a double-blind randomized sham-controlled crossover study, 20 CH patients received LF or sham stimulation for 30 min on two separate days. We recorded headache characteristics, cephalic autonomic symptoms (CAS), plasma levels of parasympathetic markers such as pituitary adenylate cyclase-activating polypeptide-38 (PACAP38) and vasoactive intestinal peptide (VIP), and mechanical detection and pain thresholds as a marker of sensory modulation. Results In the immediate phase (0–60 min), 16 (80%) patients experienced CAS after LF stimulation, while nine patients (45%) reported CAS after sham ( p = 0.046). We found no difference in induction of cluster-like attacks between LF stimulation (n = 7) and sham stimulation (n = 5) ( p = 0.724). There was no difference in mechanical detection and pain thresholds, and in PACAP and VIP plasma concentrations between LF and sham stimulation ( p ≥ 0.162). Conclusion LF stimulation of the SPG induced autonomic symptoms, but no CH attacks. These data suggest that increased parasympathetic outflow is not sufficient to induce CH attacks in patients. Study protocol ClinicalTrials.gov registration number NCT02510729