Energy landscapes, lowest gaps, and susceptibility of elastic manifolds at zero temperature

We study the effect of an external field on (1+1) and (2+1) dimensional elastic manifolds, at zero temperature and with random bond disorder. Due to the glassy energy landscape the configuration of a manifold changes often in abrupt, ``first order'' -type of large jumps when the field is applied. First the scaling behavior of the energy gap between the global energy minimum and the next lowest minimum of the manifold is considered, by employing exact ground state calculations and an extreme statistics argument. The scaling has a logarithmic prefactor originating from the number of the minima in the landscape, and reads $\Delta E_1 \sim L^\theta [\ln(L_z L^{-\zeta})]^{-1/2}$, where $\zeta$ is the roughness exponent and $\theta$ is the energy fluctuation exponent of the manifold, $L$ is the linear size of the manifold, and $L_z$ is the system height. The gap scaling is extended to the case of a finite external field and yields for the susceptibility of the manifolds $\chi_{tot} \sim L^{2D+1-\theta} [(1-\zeta)\ln(L)]^{1/2}$. We also present a mean field argument for the finite size scaling of the first jump field, $h_1 \sim L^{d-\theta}$. The implications to wetting in random systems, to finite-temperature behavior and the relation to Kardar-Parisi-Zhang non-equilibrium surface growth are discussed.Comment: 20 pages, 22 figures, accepted for publication in Eur. Phys. J.

Intermittence and roughening of periodic elastic media

We analyze intermittence and roughening of an elastic interface or domain wall pinned in a periodic potential, in the presence of random-bond disorder in (1+1) and (2+1) dimensions. Though the ensemble average behavior is smooth, the typical behavior of a large sample is intermittent, and does not self-average to a smooth behavior. Instead, large fluctuations occur in the mean location of the interface and the onset of interface roughening is via an extensive fluctuation which leads to a jump in the roughness of order $\lambda$, the period of the potential. Analytical arguments based on extreme statistics are given for the number of the minima of the periodicity visited by the interface and for the roughening cross-over, which is confirmed by extensive exact ground state calculations.Comment: Accepted for publication in Phys. Rev.

Deeply Dissected Tundra Polygons on a Glacio-Fluvial Outwash Plain, Northern Ungava Peninsula, Québec

Deeply dissected tundra polygons are described from the continuous permafrost environment of northernmost Ungava. They are developed on a glacial outwash plain, formed subsequent to déglaciation of the site about 7,500 BP. The exposed surfaces of the polygons are sparsely vegetated and aeolian deflation has removed their sandy matrix material. The furrows between the polygons attain depths of 0.5-2 m. From the base of one. a 0.25 m wide wedge of peat and sandy material penetrates to a minimum depth of 0.7 m (the frost table depth). Radiocarbon dates of 1650 ± 60 BP and 740 ± 80 BP indicate that progressive filling of this fissure accompanied decay of a preexisting ice-wedge. The present low mean annual air temperature at the site ( - 70C) suggests that thawing of the ice-wedges may be related more to local dynamic factors, such as deflation and improved local drainage associated with fluvial dissection, than to regional climatic amelioration. Wedge ice is believed to still underlie the polygon furrows.On décrit ici les polygones de toundra profondément disséqués de la zone de pergélisol continu de l'extrémité nord de l'Ungava. Ils se sont développés sur une plaine d'êpandage fluvio-glaciaire qui s'est formée à la suite de la déglaciation vers 7500 BP. Une végétation rare occupe la surface exposée des polygones et la déflation a emporté la matrice sablonneuse. La profondeur des sillons entre les polygones atteint de 0,5 à 2 m. À la base d'un d'entre eux, on observe une fente large de 0,25 m à remplissage composé de lentilles de tourbe et de sable, jusqu'à au moins 0,7 m de profondeur (front de dégel). Deux datations au 14C de 1650 ± 60 BP et de 740 ± 80 BP montrent que le remplissage progressif de la fissure s'est fait au fur et à mesure de la désintégration d'une fente de gel préexistante. La basse température moyenne annuelle de - 7°C indique que la fonte des fentes de gel dépend davantage de facteurs dynamiques locaux, comme la déflation et un meilleur drainage, qu'à une amélioration du climat. On croit que des fentes de gel occupent encore la partie inférieure des sillons de polygone

Extremal statistics in the energetics of domain walls

We study at T=0 the minimum energy of a domain wall and its gap to the first excited state concentrating on two-dimensional random-bond Ising magnets. The average gap scales as $\Delta E_1 \sim L^\theta f(N_z)$, where $f(y) \sim [\ln y]^{-1/2}$, $\theta$ is the energy fluctuation exponent, $L$ length scale, and $N_z$ the number of energy valleys. The logarithmic scaling is due to extremal statistics, which is illustrated by mapping the problem into the Kardar-Parisi-Zhang roughening process. It follows that the susceptibility of domain walls has also a logarithmic dependence on system size.Comment: Accepted for publication in Phys. Rev.

Pretibial hematomas – A real-world single-center study

Publisher Copyright: © 2022 The Author(s)We analyzed treatment, outcome, and risk factors for skin necrosis of 60 patients aged ≥65 years treated for a pretibial hematoma in the province of Kymenlaakso, Finland, between 2015 and 2019. Reviewing patients’ medical records revealed two cohorts with distinct trajectories in outcome. By comparing the cohorts, we were able to discover factors associated with the prognosis for generating skin necrosis and the need for operative treatment. Thirty-five (58.3%) patients healed without any management, and 25 (41.7%) patients were treated with hematoma evacuation, mostly for having generated skin necrosis (72%). Among operatively treated patients’ descriptions, such as “parchment skin” and “poor skin quality” were observed frequently (80%) in the medical records. This pathology, dermatoporosis, was statistically significant (p<0.0001) among patients with a complicated outcome of a pretibial hematoma. In addition to dermatoporosis, patients with hematoma evacuation were more fragile having a higher Charlson comorbidity index (p = 0.005), a greater need for a walking aid (p = 0.0002), and overall compromised independency (p = 0.033). Hospitalization and rehabilitation were prolonged in the operatively treated cohort, 6.4 days vs. 2 days, respectively. We recorded a delay in the diagnosis and hematoma evacuation (mean 6, range 0–51 days). In addition, six (10%) patients were misdiagnosed for having erysipelas or deep vein thrombosis indicating that pretibial hematomas are not recognized. Skin quality should be documented, and prompt surgical hematoma evacuation should be executed in fragile patients with dermatoporosis. This could prevent skin necrosis and the further need of wound care or surgical care, long hospitalization, and rehabilitation periods.Peer reviewe

Pretibial lacerations among elderly patients : A province-wide study from Kymenlaakso, Finland, 2015-2019

In this retrospective cohort study, we analysed treatment and outcomes among >= 65-year-old patients who experienced a traumatic pretibial laceration in the province of Kymenlaakso, Finland, between 2015 and 2019. We reviewed computerised medical records for 116 patients with a pretibial laceration, 107 of whom we analysed in further detail. Patients were traced from injury to healing, including rehabilitation periods in health care centres. As expected, the majority of patients were elderly women (67%). Most lacerations were superficial and small, explaining why treatment was mostly conservative. Only 11 (9.48%) patients were treated operatively with surgical debridement or a split-thickness skin graft. The number of overall complications in wounds was high, with a complication rate of 30.2%. Most complications were local wound infections. We found that wound healing took more than 3 months in 32% of patients. Thorough patient tracing revealed numerous follow-up visits and long rehabilitative hospitalisation periods, indicating a significant decline in patient independence and the excessive use of resources. Successful wound healing was eventually observed in 89.66% patients. Furthermore, no terminology regarding pretibial lacerations was found in patient records. This study indicates that pretibial lacerations remain poorly recognised and understood in Finland. (C) 2021 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.Peer reviewe

Eye fluke-induced cataracts in natural fish populations: is there potential for host manipulation?

Manipulation of host phenotype (e.g. behaviour, appearance) is suggested to be a common strategy to enhance transmission in trophically transmitted parasites. However, in many systems, evidence of manipulation comes exclusively from laboratory studies and its occurrence in natural host populations is poorly understood. Here, we examined the potential for host manipulation by Diplostomum eye flukes indirectly by quantifying the physiological effects of parasites on fish. Earlier laboratory studies have shown that Diplostomum infection predisposes fish to predation by birds (definitive hosts of the parasites) by reducing fish vision through cataract formation. However, occurrence of cataracts and the subsequent potential for host manipulation in natural fish populations has remained poorly explored. We studied the occurrence of eye fluke-induced cataracts from 7 common fish species (Gymnocephalus cernuus, Rutilus rutilus, Leuciscus leuciscus, Alburnus alburnus, Osmerus eperlanus, Coregonus lavaretus and Gasterosteus aculeatus) from the Bothnian Bay in the Baltic Sea. We found that the parasite-induced cataracts were common in fish and they also reached high levels which are likely to predispose fish to predation. However, we observed such cataracts only in species with the highest parasite abundances, which suggests that only certain hosts may be strongly affected by the infectio

Editorial:Identification, risk stratification, and optimized management for Lynch Syndrome

Non peer reviewe

Seasonal changes in host phenotype manipulation by an acanthocephalan: time to be transmitted?

Many complex life cycle parasites exhibit seasonal transmission between hosts. Expression of parasite traits related to transmission, such as the manipulation of host phenotype, may peak in seasons when transmission is optimal. The acanthocephalan Acanthocephalus lucii is primarily transmitted to its fish definitive host in spring. We assessed whether the parasitic alteration of 2 traits (hiding behaviour and coloration) in the isopod intermediate host was more pronounced at this time of year. Refuge use by infected isopods was lower, relative to uninfected isopods, in spring than in summer or fall. Infected isopods had darker abdomens than uninfected isopods, but this difference did not vary between seasons. The level of host alteration was unaffected by exposing isopods to different light and temperature regimes. In a group of infected isopods kept at 4°C, refuge use decreased from November to May, indicating that reduced hiding in spring develops during winter. Keeping isopods at 16°C instead of 4°C resulted in higher mortality but not accelerated changes in host behaviour. Our results suggest that changes in host and/or parasite age, not environmental conditions, underlie the seasonal alteration of host behaviour, but further work is necessary to determine if this is an adaptive parasite strategy to be transmitted in a particular seaso

Acanthocephalan size and sex affect the modification of intermediate host colouration

For trophically transmitted parasites, transitional larval size is often related to fitness. Larger parasites may have higher establishment success and/or adult fecundity, but prolonged growth in the intermediate host increases the risk of failed transmission via natural host mortality. We investigated the relationship between the larval size of an acanthocephalan (Acanthocephalus lucii) and a trait presumably related to transmission, i.e. altered colouration in the isopod intermediate host. In natural collections, big isopods harboured larger worms and had more modified (darker) abdominal colouration than small hosts. Small isopods infected with a male parasite tended to have darker abdominal pigmentation than those infected with a female, but this difference was absent in larger hosts. Female size increases rapidly with host size, so females may have more to gain than males by remaining in and growing mutually with small hosts. In experimental infections, a large total parasite volume was associated with darker host respiratory operculae, especially when it was distributed among fewer worms. Our results suggest that host pigment alteration increases with parasite size, albeit differently for male and female worms. This may be an adaptive strategy if, as parasites grow, the potential for additional growth decreases and the likelihood of host mortality increase