Magmatic-hydrothermal evolution of the Hoidas Lake REE deposit, northern Saskatchewan, Canada

The Hoidas Lake rare earth element (REE) deposit in northern Saskatchewan, Canada, was investigated through field observations, detailed petrographic studies, scanning electron microscopy coupled with energy dispersive X-ray spectrometry (SEM-EDS) and electron microprobe analyses (EMPA), fluid inclusion microthermometry and in situ U-Pb, Lu-Hf and Sm-Nd isotopic studies, in order to unravel the magmatic-hydrothermal evolution of the deposit. The main aims were to evaluate the source and chemical variations of the fluids and melts that formed the mineralization and to provide constraints on the age of the deposit. The structurally controlled mineralization consists of diopside-allanite veins and apatite breccia veins emplaced along the Hoidas-Nisikkatch Fault. In the diopside-allanite veins the allanites, commonly intergrown with hyalophane, titanite and diopside, show chemical variations that reflect relative REE-depletion in the melt during allanite crystallization, and subsequent REE-enrichment, possibly due to open system behavior and a new influx of melt/fluid into the vein system. The later apatite breccia veins show multiple phases of crystallization and a shift from Ce-dominance in the earlier red and green apatite phases to Nd-dominance in the latest coarse red apatite phase, which reflects a transition from magmatic to hydrothermal growth. Interaction with hydrothermal fluids resulted in chlorite-hematite alteration, irregular REE zonation in allanite and apatite, and local redistribution of the REEs into secondary monazite, REE-carbonates and REE-Sr-carbonates. Late quartz-carbonate veins that represent this hydrothermal overprint occasionally contain allanite, interpreted to have formed through hydrothermal remobilization of the REEs. The paragenetic relationships of the REE veins with hyalophane-bearing pegmatite dikes and late lamprophyre dikes and the mineral chemistry of the REE-bearing phases indicate a mantle-derived, most probably carbonatitic source for the melts and fluids responsible for the mineralization. The various vein generations formed due to repeated influxes of the mineralizing melts and fluids into the vein system, and caused limited Ba-metasomatism and albitization in the wall rocks. Unusual LREE-rich primary graphic-textured inclusions in the apatite of the Hoidas Lake deposit were studied through integrated EMPA and SEM-EDS imaging, and show variable compositions between Ce2O3+SiO2(+ThO2)-dominant and La2O3+Nd2O3(+F)-dominant end members. These inclusions indicate rapid apatite growth and contemporaneous crystallization of REE-enriched phases from the boundary-layer melt phase at the apatite-melt interface or alternatively, trapping of a melt phase during apatite growth due to melt-melt immiscibility. The fluid inclusion microthermometric data and evaporate mound analysis of the apatite breccia veins and related hyalophane-bearing pegmatites and quartz-carbonate veins suggest that entrapment of the hydrothermal fluids at Hoidas Lake occurred below 310°C, and pressure was transient between 0.5 and 2 kbars. Evolution of the Hoidas Lake mineralization involved early entrapment of a carbonic fluid followed by introduction of mixed Na-Ca-K-(Ba-Mn-Mg-Fe-Sr) aqueous fluids that were responsible for the late alteration of the mineralized veins and local redistribution of the REEs into secondary phases. Combination of the aforementioned studies indicates that the Hoidas Lake REE mineralization is a distal magmatic-hydrothermal counterpart of the hidden carbonatitic or alkaline igneous source. Geological relationships and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U-Pb geochronology of various mineral phases indicate that the REE-bearing veins formed after peak metamorphism in the Hoidas Lake area, which occurred at ca. 1.9 Ga. However, zircon crystals with concordant U-Pb dates of ca. 2350 Ma are interpreted to be inherited from granitoids that formed during the Arrowsmith Orogeny, also reported from other parts of the southern Rae Subprovince. Zircon rims that show concordant U-Pb ages around 1905 Ma represent new zircon growth during the emplacement of the REE mineralization and have considerably different Hf isotopic compositions, compared to the inherited zircon cores. Concordia ages of titanite from two distinct samples are ca. 1900 Ma and 1830 Ma and two monazite U-Pb date groups were observed at ca. 1910 Ma and 1845 Ma. The U-Pb dates correspond to the estimated period of tectonic activity of the Black Bay Fault System. The Sm-Nd isotopic systematics of titanite, green apatite and monazite are comparable to those previously reported for the Martin Group alkali basalts in the Beaverlodge Domain and the ultrapotassic rocks of the Christopher Island Formation in the Baker Lake Basin, both of which also yielded similar U-Pb ages to those of the Hoidas Lake veins. These regionally occurring alkali units likely originated from a similar source, most probably an ancient enriched lithospheric mantle reservoir

Battery Technology – Use in Forestry

Technical development and system optimization during the last decades have targeted more efficient, socially acceptable and ecologically sustainable ways to use forestry machines and tools. This is supported by the development of electronics and electrical components, as well as battery technology, without which it is impossible to imagine doing some forestry work in forest areas with no permanent source of electricity. Today, we cannot imagine life without e.g. a cell phone, and also doing business in the forestry sector without a field computer. There are numerous examples in everyday life, but also in industry, where portable devices make life and business much easier, and the basis for the operation of these devices is battery technology. The importance of the development of battery technology is proven by the fact that in 2019 the Nobel Prize in Chemistry went into the hands of scientists who developed a lithium-ion battery - a lightweight, rechargeable and powerful battery that is used today in numerous products from mobile phones to laptops and electric vehicles. This paper will outline the historical development of battery technology and the use of battery powered devices, tools and machines with their advantages and disadvantages in forestry sector

Association of extraintestinal manifestations of inflammatory bowel disease in a province of western Hungary with disease phenotype: Results of a 25-year follow-up study

AIM: IBD is a systemic disease associated with a large number of extraintestinal manifestations (EIMs). Our aim was to determine the prevalence of EIMs in a large IBD cohort in Veszprem Province in a 25-year follow-up study. METHODS: Eight hundred and seventy-three IBD patients were enrolled (ulcerative colitis/UC/: 619, m/f: 317/302, mean age at presentation: 38.3 years, average disease duration: 11.2 years; Crohn's disease/CD/: 254, m/f: 125/129, mean age at presentation: 32.5 years, average disease duration: 9.2 years). Intestinal, extraintestinal signs and laboratory tests were monitored regularly. Any alteration suggesting an EIMs was investigated by a specialist. RESULTS: A total of 21.3 % of patients with IBD had EIM (UC: 15.0 %, CD: 36.6 %). Age at presentation did not affect the likelihood of EIM. Prevalence of EIMs was higher in women and in CD, ocular complications and primary sclerosing cholangitis (PSC) were more frequent in UC. In UC there was an increased tendency of EIM in patients with a more extensive disease. Joint complications were more frequent in CD (22.4 % vs UC 10.2 %, P<0.01). In UC positive family history increased the risk of joint complications (OR:3.63). In CD the frequency of type-1 peripheral arthritis was increased in patients with penetrating disease (P=0.028). PSC was present in 1.6 % in UC and 0.8 % in CD. Dermatological complications were present in 3.8 % in UC and 10.2 % in CD, the rate of ocular complications was around 3 % in both diseases. Rare complications were glomerulonephritis, autoimmune hemolytic anaemia and celiac disease. CONCLUSION: Prevalence of EIM in Hungarian IBD patients is in concordance with data from Western countries. The high number of EIM supports a role for complex follow-up in these patients

Computing interior eigenvalues and corresponding eigenvectors of definite matrix pairs

U prvom dijelu ove disertacije predstavljamo nove algoritme koji za dani hermitski matrični par $(A, B)$ ispituju je li on pozitivno definitan, u smislu da postoji realan broj $\lambda_0$ takav da je matrica $A-\lambda_0B$ pozitivno definitna. Skup svih takvih $\lambda_0$ čini otvoreni interval koji zovemo definitan interval, a bilo koji takav $\lambda_0$ zovemo definitan pomak. Najjednostavniji algoritmi ispitivanja koje predlažemo temelje se na ispitivanju glavnih podmatrica reda 1 ili 2. Također razvijamo efikasniji algoritam ispitivanja potprostora uz pretpostavku indefinitnosti matrice B. Taj se algoritam temelji na iterativnom ispitivanju malih gusto popunjenih komprimiranih parova koji nastaju korištenjem test-potprostora malih dimenzija, a predlažemo i ubrzanje samog algoritma. Algoritam ispitivanja potprostora posebno je pogodan za velike rijetko popunjene vrpčaste matrične parove, a može se primijeniti u ispitivanju hiperbolnosti kvadratnog svojstvenog problema. U drugom dijelu ove disertacije za dani pozitivno definitni matrični par $(A, B)$ reda $n$ s indefinitnom matricom $B$ konstruiramo nove algoritme minimizacije traga funkcije $f(X)=X^HAX$ uz uvjet $X^HBX=diag(I_{k_+}, -I_{k_-})$ gdje je $X \in \mathbb{C}^{n \times (k_++k_-)}, 1 \leq k_+ \leq n_+, 1 \leq k_- \leq n_-$ i $(n_+, n_-, n_0)$ inercija matrice $B$. Predlažemo opći indefinitni algoritam, te razvijamo efikasne algoritme prekondicioniranih gradijentnih iteracija koje smo nazvali indefinitna $m$-shema. Stoga metode indefinitne $m$-sheme za dani pozitivno definitni par i jedan ili dva definitna pomaka (koji se mogu dobiti algoritmom ispitivanja potprostora) istovremeno računaju manji broj unutarnjih svojstvenih vrijednosti oko definitnog intervala i pridružene svojstvene vektore. Također, dajemo ideje kako računati manji broj svojstvenih vrijednosti oko bilo kojeg broja unutar rubova spektra, a izvan definitnog intervala, i pridruženih svojstvenih vektora, danog pozitivno definitnog matričnog para koristeći pozitivno definitnu matricu prekondicioniranja. Algoritmi su posebno pogodni za velike rijetko popunjene matrične parove. Nizom numeričkih eksperimenata pokazujemo efikasnost samih algoritama ispitivanja i algoritama računanja unutarnjih svojstvenih vrijednosti i pridruženih svojstvenih vektora. Efikasnost naših metoda uspoređujemo s nekim postojećim metodama.The generalized eigenvalue problem (GEP) for given matrices $A, B \in \mathbb{C}^{n \times n}$ is to find scalars $\lambda$ and nonzero vectors $x \in \mathbb{C}^n$ such that $Ax = \lambda Bx$ (1). The pair $(\lambda, x)$ is called an eigenpair, $\lambda$ is an eigenvalue and $x$ corresponding eigenvector. GEP (1) where A and B are both Hermitian, or real symmetric, occurs in many applications of mathematics. Very important case is when B (and A) is positive definite (appearing, e.g., in the finite element discretization of self-adjoint and elliptic PDE-eigenvalue problem [25]). Another very important case is when B (and A) is indefinite, but the matrix pair (A, B) is definite, meaning, there exist real numbers $\alpha, \beta$ such that the matrix $\alpha A + \beta B$ is positive definite (appearing, e.g., in mechanics [83] and computational quantum chemistry [4]). Many theoretical properties (variational principles, perturbation theory, etc.) and eigenvalue solvers for Hermitian matrix are extended to definite matrix pairs [64, 79, 83]. A Hermitian matrix pair (A, B) is called positive (negative) definite if there exists a real $\lambda_0$ such that $A- \lambda_0 B$ is positive ( negative) definite. The set of all such $\lambda_0$ is an open interval called the definiteness interval [83], and any such $\lambda_0$ will be called definitizing shift. In the first part of this thesis we propose new algorithms for detecting definite Hermitian matrix pairs (A, B). The most simple algorithms we propose are based on testing the main submatrices of order 1 or 2. These algorithms do not have to give a final answer about (in)definiteness of the given pair, so we develop a more efficient subspace algorithm assuming B is indefinite. Our subspace algorithm for detecting definiteness is based on iterative testing of small full compressed matrix pairs formed using test-subspaces of small dimensions. It is generalization of the method of coordinate relaxation proposed in [36, Section 3.6]. We also propose acceleration of the subspace algorithm in a way that certain linear systems must be solved in every or in some iteration steps. If the matrix pair is definite, the subspace algorithm detects if it is positive or negative definite and returns one definitizing shift. The subspace algorithm is particulary suited for large, sparse and banded matrix pairs, and can be used in testing hyperbolicity of a Hermitian quadratic matrix polynomial. Numerical experiments are given which illustrate efficiency of several variants of our subspace algorithm and comparison is made with an arc algorithm [19, 17, 29]. In the second part of this thesis we are interested in solving partial positive definite GEP (1) where B (and A) is indefinite (both A and B can be singular). Specifically, we are interested in iterative algorithms which will compute a small number of eigenvalues closest to the definiteness interval and corresponding eigenvectors. These algorithms are based on trace minimization property [41, 49]: find the minimum of the trace of the function: $f(X)=X^HAX$ such that $X^HBX=diag(I_{k_+}, -I_{k_-})$ where $X \in \mathbb{C}^{n \times (k_++k_-)}, 1 \leq k_+ \leq n_+, 1 \leq k_- \leq n_-$ and $(n_+, n_-, n_0)$ is the inertia of B. The class of algorithms we propose will be preconditioned gradient type iteration, suitable for large and sparse matrices, previously studied for the case with A and/or B are known to be positive definite (for a survey of preconditioned iterations see [3, 39]). In the recent paper [42] an indefinite variants of LOBPCG algorithm [40] were suggested. The authors of [42] were not aware of any other preconditioned eigenvalue solver tailored to definite matrix pairs with indefinite matrices. In this thesis we propose some new preconditioned eigenvalue solvers suitable for this case, which include truncated and extended versions of indefinite LOBPCG from [42]. Our algorithms use one or two definitizing shifts. For the truncated versions of indefinite LOBPCG, which we call indefinite BPSD/A, we derive a sharp convergence estimates. Since for the LOBPCG type algorithms there are still no sharp convergence estimates, estimates derived for BPSD/A type methods serve as an upper (non-sharp) convergence estimates. We also devise some possibilities of using our algorithms to compute a modest number of eigenvalues around any spectral gap of a definite matrix pair (A, B). Numerical experiments are given which illustrate efficiency and some limitations of our algorithms

Computing interior eigenvalues and corresponding eigenvectors of definite matrix pairs

U prvom dijelu ove disertacije predstavljamo nove algoritme koji za dani hermitski matrični par $(A, B)$ ispituju je li on pozitivno definitan, u smislu da postoji realan broj $\lambda_0$ takav da je matrica $A-\lambda_0B$ pozitivno definitna. Skup svih takvih $\lambda_0$ čini otvoreni interval koji zovemo definitan interval, a bilo koji takav $\lambda_0$ zovemo definitan pomak. Najjednostavniji algoritmi ispitivanja koje predlažemo temelje se na ispitivanju glavnih podmatrica reda 1 ili 2. Također razvijamo efikasniji algoritam ispitivanja potprostora uz pretpostavku indefinitnosti matrice B. Taj se algoritam temelji na iterativnom ispitivanju malih gusto popunjenih komprimiranih parova koji nastaju korištenjem test-potprostora malih dimenzija, a predlažemo i ubrzanje samog algoritma. Algoritam ispitivanja potprostora posebno je pogodan za velike rijetko popunjene vrpčaste matrične parove, a može se primijeniti u ispitivanju hiperbolnosti kvadratnog svojstvenog problema. U drugom dijelu ove disertacije za dani pozitivno definitni matrični par $(A, B)$ reda $n$ s indefinitnom matricom $B$ konstruiramo nove algoritme minimizacije traga funkcije $f(X)=X^HAX$ uz uvjet $X^HBX=diag(I_{k_+}, -I_{k_-})$ gdje je $X \in \mathbb{C}^{n \times (k_++k_-)}, 1 \leq k_+ \leq n_+, 1 \leq k_- \leq n_-$ i $(n_+, n_-, n_0)$ inercija matrice $B$. Predlažemo opći indefinitni algoritam, te razvijamo efikasne algoritme prekondicioniranih gradijentnih iteracija koje smo nazvali indefinitna $m$-shema. Stoga metode indefinitne $m$-sheme za dani pozitivno definitni par i jedan ili dva definitna pomaka (koji se mogu dobiti algoritmom ispitivanja potprostora) istovremeno računaju manji broj unutarnjih svojstvenih vrijednosti oko definitnog intervala i pridružene svojstvene vektore. Također, dajemo ideje kako računati manji broj svojstvenih vrijednosti oko bilo kojeg broja unutar rubova spektra, a izvan definitnog intervala, i pridruženih svojstvenih vektora, danog pozitivno definitnog matričnog para koristeći pozitivno definitnu matricu prekondicioniranja. Algoritmi su posebno pogodni za velike rijetko popunjene matrične parove. Nizom numeričkih eksperimenata pokazujemo efikasnost samih algoritama ispitivanja i algoritama računanja unutarnjih svojstvenih vrijednosti i pridruženih svojstvenih vektora. Efikasnost naših metoda uspoređujemo s nekim postojećim metodama.The generalized eigenvalue problem (GEP) for given matrices $A, B \in \mathbb{C}^{n \times n}$ is to find scalars $\lambda$ and nonzero vectors $x \in \mathbb{C}^n$ such that $Ax = \lambda Bx$ (1). The pair $(\lambda, x)$ is called an eigenpair, $\lambda$ is an eigenvalue and $x$ corresponding eigenvector. GEP (1) where A and B are both Hermitian, or real symmetric, occurs in many applications of mathematics. Very important case is when B (and A) is positive definite (appearing, e.g., in the finite element discretization of self-adjoint and elliptic PDE-eigenvalue problem [25]). Another very important case is when B (and A) is indefinite, but the matrix pair (A, B) is definite, meaning, there exist real numbers $\alpha, \beta$ such that the matrix $\alpha A + \beta B$ is positive definite (appearing, e.g., in mechanics [83] and computational quantum chemistry [4]). Many theoretical properties (variational principles, perturbation theory, etc.) and eigenvalue solvers for Hermitian matrix are extended to definite matrix pairs [64, 79, 83]. A Hermitian matrix pair (A, B) is called positive (negative) definite if there exists a real $\lambda_0$ such that $A- \lambda_0 B$ is positive ( negative) definite. The set of all such $\lambda_0$ is an open interval called the definiteness interval [83], and any such $\lambda_0$ will be called definitizing shift. In the first part of this thesis we propose new algorithms for detecting definite Hermitian matrix pairs (A, B). The most simple algorithms we propose are based on testing the main submatrices of order 1 or 2. These algorithms do not have to give a final answer about (in)definiteness of the given pair, so we develop a more efficient subspace algorithm assuming B is indefinite. Our subspace algorithm for detecting definiteness is based on iterative testing of small full compressed matrix pairs formed using test-subspaces of small dimensions. It is generalization of the method of coordinate relaxation proposed in [36, Section 3.6]. We also propose acceleration of the subspace algorithm in a way that certain linear systems must be solved in every or in some iteration steps. If the matrix pair is definite, the subspace algorithm detects if it is positive or negative definite and returns one definitizing shift. The subspace algorithm is particulary suited for large, sparse and banded matrix pairs, and can be used in testing hyperbolicity of a Hermitian quadratic matrix polynomial. Numerical experiments are given which illustrate efficiency of several variants of our subspace algorithm and comparison is made with an arc algorithm [19, 17, 29]. In the second part of this thesis we are interested in solving partial positive definite GEP (1) where B (and A) is indefinite (both A and B can be singular). Specifically, we are interested in iterative algorithms which will compute a small number of eigenvalues closest to the definiteness interval and corresponding eigenvectors. These algorithms are based on trace minimization property [41, 49]: find the minimum of the trace of the function: $f(X)=X^HAX$ such that $X^HBX=diag(I_{k_+}, -I_{k_-})$ where $X \in \mathbb{C}^{n \times (k_++k_-)}, 1 \leq k_+ \leq n_+, 1 \leq k_- \leq n_-$ and $(n_+, n_-, n_0)$ is the inertia of B. The class of algorithms we propose will be preconditioned gradient type iteration, suitable for large and sparse matrices, previously studied for the case with A and/or B are known to be positive definite (for a survey of preconditioned iterations see [3, 39]). In the recent paper [42] an indefinite variants of LOBPCG algorithm [40] were suggested. The authors of [42] were not aware of any other preconditioned eigenvalue solver tailored to definite matrix pairs with indefinite matrices. In this thesis we propose some new preconditioned eigenvalue solvers suitable for this case, which include truncated and extended versions of indefinite LOBPCG from [42]. Our algorithms use one or two definitizing shifts. For the truncated versions of indefinite LOBPCG, which we call indefinite BPSD/A, we derive a sharp convergence estimates. Since for the LOBPCG type algorithms there are still no sharp convergence estimates, estimates derived for BPSD/A type methods serve as an upper (non-sharp) convergence estimates. We also devise some possibilities of using our algorithms to compute a modest number of eigenvalues around any spectral gap of a definite matrix pair (A, B). Numerical experiments are given which illustrate efficiency and some limitations of our algorithms

Workability and Physical Wellbeing Among Chainsaw Operators in Croatia

Motor-manual felling and wood processing is a high-risk work process where the chainsaw, in connection to other variables in the working environment, is a key and constant source of risk and danger for forest chainsaw operators. Pursuant to the foregoing, the purpose of this research is to investigate and compare detected musculoskeletal disorder (MSD) symptoms among the chainsaw workers in Croatia according to their employer (state company – Hrvatske šume Ltd. or private forestry contractor) and self-evaluated Workability Index. A combined three-stage research method was used: (a) defining a sample; (b) preparation and administration of questionnaire; and (c) data analysis and elaboration. The Standardized Nordic Questionnaire (SNQ) was used as a medium to detect musculoskeletal disorder symptoms in chainsaw operators and the Workability Index (WAI) questionnaire was used as a medium for workability self-evaluation. The field part of face-to-face data collection was conducted in the first quarter of 2022 with a total of 158 sampled workers interviewed directly at the forest worksite. Descriptive and inferential statistical methods were used to verify and analyze the data. The anatomical area with the highest 12-month period prevalence of MSD symptoms for all chainsaw operators is the low back (70.89%), followed by the shoulders (41.14%), neck (39.87%) and wrist/hands (36.71%). Research results, according to the employer, showed that workers employed by Hrvatske šume Ltd. have a higher prevalence of MSD symptoms in almost all anatomical locations compared to chainsaw operators employed by private forest contractors. Mean WAI Score among all respondents was 34.96 points (max. 49) falling into the rank »moderate«, while the current workability compared with the lifetime best was 7.33 (range 0–10). The results of MSD symptoms confirm the self-estimated higher values related to health problems caused by forestry work and lower WAI Score by workers employed in the state forestry sector compared to workers employed in private forestry sector. The prevalence of MSD symptoms, observed through WAI Score, showed a significantly lower percentage of affirmative responses for all anatomical regions except for shoulders in workers who need to maintain their workability. The obtained results show positive correlation with descriptive indicators, where younger workers with less chainsaw work experience have a lower prevalence of MSD symptoms and better WAI Score. In the discussion and conclusion part of the research in question, the need for development of possible solutions is emphasized. The proposed solutions can be included into educational programs or on-site training related to the MSD risks for professional chainsaw workers to change their behaviour that will reduce occupational risks