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1.
J Phys Chem A ; 128(13): 2672-2679, 2024 Apr 04.
Article in English | MEDLINE | ID: mdl-38530789

ABSTRACT

Photoemission orbital tomography (POT) from photoelectron momentum maps (PMMs) is a powerful technique that visualizes the shape of the molecular orbitals (MOs) of molecular films. For further utilization of POT, a simple and low-cost method of POT is highly required. Here, we propose a new POT method based on the PhaseLift algorithm (PhaseLift POT). This method utilizes a lifting procedure to convert the PMM, which is a second-order polynomial of MO coefficients, into a first-order polynomial of the lifted MO coefficients and further relaxes the equality constraint for a given PMM. We also established a method to improve the accuracy of phase retrieval from the noisy PMM data by using sparsity for MO coefficients (sparse PhaseLift POT). These methods make it possible to reconstruct the three-dimensional MOs, including phases of the wave function, directly from a single experimental PMM. This method can also precisely determine the adsorption-induced molecular deformations with an accuracy of 0.05 [Å]. Furthermore, the robust sparse PhaseLift POT is robust against unavoidable noise in the experimental PMMs due to the relaxation of the matching condition for a given PMM. Therefore, this will be an innovative tool for POT, especially for analyzing the dynamics of the molecules during the chemical reaction and excitation processes.

2.
Phys Rev Lett ; 127(7): 077201, 2021 Aug 13.
Article in English | MEDLINE | ID: mdl-34459637

ABSTRACT

We report ^{51}V NMR and inelastic neutron scattering (INS) measurements on a quasi-1D antiferromagnet BaCo_{2}V_{2}O_{8} under transverse field along the [010] direction. The scaling behavior of the spin-lattice relaxation rate above the Néel temperatures unveils a 1D quantum critical point (QCP) at H_{c}^{1D}≈4.7 T, which is masked by the 3D magnetic order. With the aid of accurate analytical analysis and numerical calculations, we show that the zone center INS spectrum at H_{c}^{1D} is precisely described by the pattern of the 1D quantum Ising model in a magnetic field, a class of universality described in terms of the exceptional E_{8} Lie algebra. These excitations are nondiffusive over a certain field range when the system is away from the 1D QCP. Our results provide an unambiguous experimental realization of the massive E_{8} phase in the compound, and open a new experimental route for exploring the dynamics of quantum integrable systems as well as physics beyond integrability.

3.
BMC Emerg Med ; 21(1): 38, 2021 03 25.
Article in English | MEDLINE | ID: mdl-33765940

ABSTRACT

BACKGROUND: Dizziness is a relatively common symptom among patients who call for the emergency medical services (EMS). AIM: To identify factors of importance for the early identification of a time-sensitive condition behind the symptom of dizziness among patients assessed by the EMS. METHODS: All patients assessed by the EMS and triaged using Rapid Emergency Triage and Treatment (RETTS) for adults code 11 (=dizziness) in the 660,000 inhabitants in the Municipality of Gothenburg, Sweden, in 2016, were considered for inclusion. The patients were divided into two groups according to the final diagnosis (a time-sensitive condition, yes or no). RESULTS: There were 1536 patients who fulfilled the inclusion criteria, of which 96 (6.2%) had a time-sensitive condition. The majority of these had a stroke/transitory ischaemic attack (TIA). Eight predictors of a time-sensitive condition were identified. Three were associated with a reduced risk: 1) the dizziness was of a rotatory type, 2) the dizziness had a sudden onset and 3) increasing body temperature. Five were associated with an increased risk: 1) sudden onset of headache, 2) a history of head trauma, 3) symptoms of nausea or vomiting, 4) on treatment with anticoagulants and 5) increasing systolic blood pressure. CONCLUSION: Among 1536 patients who were triaged by the EMS for dizziness, 6.2% had a time-sensitive condition. On the arrival of the EMS, eight factors were associated with the risk of having a time-sensitive condition. All these factors were linked to the type of symptoms or to clinical findings on the arrival of the EMS or to the recent clinical history.


Subject(s)
Dizziness , Emergency Medical Services , Ischemic Attack, Transient , Stroke , Time Factors , Adult , Dizziness/diagnosis , Dizziness/epidemiology , Dizziness/etiology , Humans , Ischemic Attack, Transient/diagnosis , Stroke/diagnosis , Sweden , Triage
4.
Acta Neurol Scand ; 137(5): 523-530, 2018 May.
Article in English | MEDLINE | ID: mdl-29315463

ABSTRACT

OBJECTIVES: We compare various aspects in the early chain of care among patients with haemorrhagic stroke and ischaemic stroke. MATERIALS & METHODS: The Emergency Medical Services (EMS) and nine emergency hospitals, each with a stroke unit, were included. All patients hospitalised with a first and a final diagnosis of stroke between 15 December 2010 and 15 April 2011 were included. The primary endpoint was the system delay (from call to the EMS until diagnosis). Secondary endpoints were: (i) use of the EMS, (ii) delay from symptom onset until call to the EMS; (iii) priority at the dispatch centre; (iv) priority by the EMS; and (v) suspicion of stroke by the EMS nurse and physician on admission to hospital. RESULTS: Of 1336 patients, 172 (13%) had a haemorrhagic stroke. The delay from call to the EMS until diagnosis was significantly shorter in haemorrhagic stroke. The patient's decision time was significantly shorter in haemorrhagic stroke. The priority level at the dispatch centre did not differ between the two groups, whereas the EMS nurse gave a significantly higher priority to patients with haemorrhage. There was no significant difference between groups with regard to the suspicion of stroke either by the EMS nurse or by the physician on admission to hospital. CONCLUSIONS: Patients with a haemorrhagic stroke differed from other stroke patients with a more frequent and rapid activation of EMS.


Subject(s)
Brain Ischemia/diagnosis , Intracranial Hemorrhages/diagnosis , Stroke/diagnosis , Stroke/etiology , Time-to-Treatment/statistics & numerical data , Adult , Aged , Brain Ischemia/complications , Emergency Medical Services , Female , Humans , Intracranial Hemorrhages/complications , Male , Middle Aged , Retrospective Studies , Time Factors
5.
Phys Rev Lett ; 119(4): 047204, 2017 Jul 28.
Article in English | MEDLINE | ID: mdl-29341764

ABSTRACT

We observe a disappearance of the 1/3 magnetization plateau and a striking change of the magnetic configuration under a moderate doping of the model triangular antiferromagnet RbFe(MoO_{4})_{2}. The reason is an effective lifting of degeneracy of mean-field ground states by a random potential of impurities, which compensates, in the low-temperature limit, the fluctuation contribution to free energy. These results provide a direct experimental confirmation of the fluctuation origin of the ground state in a real frustrated system. The change of the ground state to a least collinear configuration reveals an effective positive biquadratic exchange provided by the structural disorder. On heating, doped samples regain the structure of a pure compound, thus allowing for an investigation of the remarkable competition between thermal and structural disorder.

6.
Clin Radiol ; 71(1): e88-95, 2016 Jan.
Article in English | MEDLINE | ID: mdl-26602937

ABSTRACT

The purpose of the present review is to discuss and display orbital lesions that demonstrate hypo-intense signal on T2-weighted images (T2WI). The physical basis for hypo-intense signal on T2WI produced by various substances is discussed. Orbital lesions that are hypo-intense on T2WI are subsequently reviewed, including a discussion on their composition as well as relevant clinical and imaging clues that may aid in their diagnosis.


Subject(s)
Magnetic Resonance Imaging/methods , Orbital Diseases/diagnosis , Contrast Media , Humans
7.
Dysphagia ; 30(3): 321-7, 2015 Jun.
Article in English | MEDLINE | ID: mdl-25750039

ABSTRACT

Age-related loss of muscle bulk and strength (sarcopenia) is often cited as a potential mechanism underlying age-related changes in swallowing. Our goal was to explore this phenomenon in the pharynx, specifically, by measuring pharyngeal wall thickness and pharyngeal lumen area in a sample of young versus older women. MRI scans of the neck were retrospectively reviewed from 60 women equally stratified into three age groups (20s, 60s, 70+). Four de-identified slices were extracted per scan for randomized, blinded analysis: one mid-sagittal and three axial slices were selected at the anterior inferior border of C2 and C3, and at the pit of the vallecula. Pixel-based measures of pharyngeal wall thickness and pharyngeal lumen area were completed using ImageJ and then converted to metric units. Measures of pharyngeal wall thickness and pharyngeal lumen area were compared between age groups with one-way ANOVAs using Sidak adjustments for post-hoc pairwise comparisons. A significant main effect for age was observed across all variables whereby pharyngeal wall thickness decreased and pharyngeal lumen area increased with advancing age. Pairwise comparisons revealed significant differences between 20s versus 70+ for all variables and 20s versus 60s for all variables except those measured at C2. Effect sizes ranged from 0.54 to 1.34. Consistent with existing sacropenia literature, the pharyngeal muscles appear to atrophy with age and consequently, the size of the pharyngeal lumen increases.


Subject(s)
Pharyngeal Muscles/physiology , Adult , Aged , Aging , Humans , Magnetic Resonance Imaging , Middle Aged , Pharyngeal Muscles/anatomy & histology , Retrospective Studies , Young Adult
8.
Phys Rev Lett ; 112(7): 077206, 2014 Feb 21.
Article in English | MEDLINE | ID: mdl-24579634

ABSTRACT

Spin-1/2 Heisenberg antiferromagnets Cs2CuCl4 and Cs2CuBr4 with distorted triangular-lattice structures are studied by means of electron spin resonance spectroscopy in magnetic fields up to the saturation field and above. In the magnetically saturated phase, quantum fluctuations are fully suppressed, and the spin dynamics is defined by ordinary magnons. This allows us to accurately describe the magnetic excitation spectra in both materials and, using the harmonic spin-wave theory, to determine their exchange parameters. The viability of the proposed method was proven by applying it to Cs2CuCl4, yielding J/kB=4.7(2) K, J'/kB=1.42(7) K, [J'/J≃0.30] and revealing good agreement with inelastic neutron-scattering results. For the isostructural Cs2CuBr4, we obtain J/kB=14.9(7) K, J'/kB=6.1(3) K, [J'/J≃0.41], providing exact and conclusive information on the exchange couplings in this frustrated spin system.

9.
Resuscitation ; 202: 110312, 2024 09.
Article in English | MEDLINE | ID: mdl-38996906

ABSTRACT

BACKGROUND: Drones are able to deliver automated external defibrillators in cases of out-of-hospital cardiac arrest (OHCA) but can be deployed for other purposes. Our aim was to evaluate the feasibility of sending live photos to dispatch centres before arrival of other units during time-critical incidents. METHODS: In this retrospective observational study, the regional dispatch centre implemented a new service using five existing AED-drone systems covering an estimated 200000 inhabitants in Sweden. Drones were deployed automatically over a 4-month study period (December 2022-April 2023) in emergency calls involving suspected OHCAs, traffic accidents and fires in buildings. Upon arrival at the scene, an overhead photo was taken and transmitted to the dispatch centre. Feasibility of providing photos in real time, and time delays intervals were examined. RESULTS: Overall, drones were deployed in 59/440 (13%) of all emergency calls: 26/59 (44%) of suspected OHCAs, 20/59 (34%) of traffic accidents, and 13/59 (22%) of fires in buildings. The main reasons for non-deployment were closed airspace and unfavourable weather conditions (68%). Drones arrived safely at the exact location in 58/59 cases (98%). Their overall median response time was 3:49 min, (IQR 3:18-4:26) vs. emergency medical services (EMS), 05:51 (IQR: 04:29-08:04) p-value for time difference between drone and EMS = 0,05. Drones arrived first on scene in 47/52 cases (90%) and the largest median time difference was found in suspected OHCAs 4:10 min, (IQR: 02:57-05:28). The time difference in the 5/52 (10%) cases when EMS arrived first the time difference was 5:18 min (IQR 2:19-7:38), p = NA. Photos were transmitted correctly in all 59 alerts. No adverse events occurred. CONCLUSION: In a newly implemented drone dispatch service, drones were dispatched to 13% of relevant EMS calls. When drones were dispatched, they arrived at scene earlier than EMS services in 90% of cases. Drones were able to relay photos to the dispatch centre in all cases. Although severely affected by closed airspace and weather conditions, this novel method may facilitate additional decision-making information during time-critical incidents.


Subject(s)
Emergency Medical Services , Out-of-Hospital Cardiac Arrest , Humans , Out-of-Hospital Cardiac Arrest/therapy , Retrospective Studies , Emergency Medical Services/methods , Sweden , Emergency Medical Service Communication Systems , Emergency Medical Dispatch/methods , Cardiopulmonary Resuscitation/methods , Defibrillators/statistics & numerical data , Feasibility Studies , Photography , Time Factors
10.
Br J Cancer ; 106(2): 290-6, 2012 Jan 17.
Article in English | MEDLINE | ID: mdl-22187036

ABSTRACT

BACKGROUND: The potential role of the renin-angiotensin system (RAS) in the promotion of tumour growth has been investigated, and the administration of RAS inhibitors, such as angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin II receptor blockers (ARBs), may improve disease control in malignancy. We investigated the prognostic impact of RAS inhibitors by analysing data from patients with upper-tract urothelial carcinoma (UTUC). METHODS: A total of 279 patients who underwent nephroureterectomy for localised UTUC (pTa-3N0M0) were identified at our three institutions. We retrospectively investigated the prognostic outcomes following nephroureterectomy in patients administered or not administered ACEIs or ARBs. RESULTS: The median follow-up period was 3.4 years. RAS inhibitors were administered to 48 patients (17.2%). Multivariate analysis showed that the appearance of pathological T3, positive lymphovascular invasion, and no RAS inhibitor administration (P=0.027 HR=3.14) were independent risk factors for a decrease in subsequent metastasis-free survival. The 5-year metastasis-free survival rate was 93.0% in patients who administered RAS inhibitors, and 72.8% in their counterparts who did not (P=0.008). CONCLUSION: The absence of RAS inhibitor administration was an independent risk factor for subsequent tumour metastasis in patients with localised UTUC. We propose RAS inhibitors may be a potent choice as an effective treatment following nephroureterectomy.


Subject(s)
Renin-Angiotensin System/drug effects , Urologic Neoplasms/drug therapy , Aged , Combined Modality Therapy , Female , Humans , Male , Nephrectomy , Prognosis , Retrospective Studies , Survival Rate , Urologic Neoplasms/pathology , Urologic Neoplasms/surgery
11.
AJNR Am J Neuroradiol ; 42(10): 1847-1852, 2021 10.
Article in English | MEDLINE | ID: mdl-34503944

ABSTRACT

BACKGROUND AND PURPOSE: Accurate differentiation of paragangliomas and schwannomas in the jugular foramen has important clinical implications because treatment strategies may vary but differentiation is not always straightforward with conventional imaging. Our aim was to evaluate the accuracy of both qualitative and quantitative metrics derived from dynamic contrast-enhanced MR imaging using golden-angle radial sparse parallel MR imaging to differentiate paragangliomas and schwannomas in the jugular foramen. MATERIALS AND METHODS: A retrospective study of imaging data was performed on patients (n = 30) undergoing MR imaging for jugular foramen masses with the golden-angle radial sparse parallel MR imaging technique. Imaging data were postprocessed to obtain time-intensity curves and quantitative parameters. Data were normalized to the dural venous sinus for relevant parameters and analyzed for statistical significance using a Student t test. A univariate logistic model was created with a binary output, paraganglioma or schwannoma, using a wash-in rate as a variable. Additionally, lesions were clustered on the basis of the wash-in rate and washout rate using a 3-nearest neighbors method. RESULTS: There were 22 paragangliomas and 8 schwannomas. All paragangliomas demonstrated a type 3 time-intensity curve, and all schwannomas demonstrated a type 1 time-intensity curve. There was a statistically significant difference between paragangliomas and schwannomas when comparing their values for area under the curve, peak enhancement, wash-in rate, and washout rate. A univariate logistic model with a binary output (paraganglioma or schwannoma) using wash-in rate as a variable was able to correctly predict all observed lesions (P < .001). All 30 lesions were classified correctly by using a 3-nearest neighbors method. CONCLUSIONS: Paragangliomas at the jugular foramen can be reliably differentiated from schwannomas using golden-angle radial sparse parallel MR imaging-dynamic contrast-enhanced imaging when imaging characteristics cannot suffice.


Subject(s)
Jugular Foramina , Neurilemmoma , Paraganglioma , Contrast Media , Humans , Magnetic Resonance Imaging , Neurilemmoma/diagnostic imaging , Paraganglioma/diagnostic imaging , Retrospective Studies
12.
Sci Adv ; 6(46)2020 11.
Article in English | MEDLINE | ID: mdl-33188020

ABSTRACT

Neurodegenerative disorders are caused by progressive neuronal loss, and there is no complete treatment available yet. Neuroinflammation is a common feature across neurodegenerative disorders and implicated in the progression of neurodegeneration. Dysregulated activation of microglia causes neuroinflammation and has been highlighted as a treatment target in therapeutic strategies. Here, we identified novel therapeutic candidate ALGERNON2 (altered generation of neurons 2) and demonstrate that ALGERNON2 suppressed the production of proinflammatory cytokines and rescued neurodegeneration in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced Parkinson's disease model. ALGERNON2 stabilized cyclinD1/p21 complex, leading to up-regulation of nuclear factor erythroid 2-related factor 2 (Nrf2), which contributes to antioxidative and anti-inflammatory responses. Notably, ALGERNON2 enhanced neuronal survival in other neuroinflammatory conditions such as the transplantation of induced pluripotent stem cell-derived dopaminergic neurons into murine brains. In conclusion, we present that the microglial potentiation of the p21-Nrf2 pathway can contribute to neuronal survival and provide novel therapeutic potential for neuroinflammation-triggered neurodegeneration.


Subject(s)
Microglia , Neurodegenerative Diseases , Animals , Disease Models, Animal , Dopaminergic Neurons/metabolism , Mice , Mice, Inbred C57BL , Microglia/metabolism , NF-E2-Related Factor 2/metabolism , Neurodegenerative Diseases/etiology , Neurodegenerative Diseases/metabolism , Neurodegenerative Diseases/therapy , Neuroinflammatory Diseases
13.
J Cell Biol ; 112(6): 1241-7, 1991 Mar.
Article in English | MEDLINE | ID: mdl-1847933

ABSTRACT

We report the immunohistochemical localization of protein kinase C isozymes (types I, II, and III) in the rabbit retina using the monospecific monoclonal antibodies MC-1a, MC-2a, and MC-3a. Using immunoblot analysis of partially purified protein kinase C preparations of rabbit retina, types II and III isozymes alone were detected. The activity of type III was the stronger. By light microscopic immunohistochemical analysis, retinal neurons were negative for type I and positive for type II and type III isozymes. Type II was more diffusely distributed through the retinal layers, but was distinctive in ganglion cells, bipolar cells, and outer segments. The immunoreactivity was stronger for type III isozyme, and it was observed in mop (rod) bipolar cells and amacrine cells. By using immunoelectron microscopy, the cytoplasm of the cell body, the axon, and dendrites of the mop bipolar cells were strongly immunoreactive for type III. The so-called rod bipolar cells were for the first time seen to form synapses with rod photoreceptor cells. These differential localizations of respective isozymes in retinal neurons suggest that each isozyme has a different site of function in each neuron.


Subject(s)
Isoenzymes/analysis , Protein Kinase C/analysis , Retina/enzymology , Retinal Ganglion Cells/enzymology , Animals , Antibodies, Monoclonal , Axons/enzymology , Axons/ultrastructure , Chromatography , Dendrites/enzymology , Dendrites/ultrastructure , Durapatite , Hydroxyapatites , Immunoblotting , Immunoenzyme Techniques , Male , Mice , Mice, Inbred BALB C/immunology , Microscopy, Immunoelectron , Rabbits , Retina/cytology , Retinal Ganglion Cells/cytology , Retinal Ganglion Cells/ultrastructure
14.
J Cell Biol ; 107(3): 929-37, 1988 Sep.
Article in English | MEDLINE | ID: mdl-3047154

ABSTRACT

Immunological analysis using monoclonal antibodies against subspecies of protein kinase C revealed the predominant expression of the isozyme, type II, in human megakaryoblastic leukemic cells. We investigated the effects of phorbol diester 12-O-tetradecanoyl phorbol-13-acetate (TPA), the Ca2+ ionophore ionomycin and synthetic diacylglycerol 1-oleoyl-2-acetylglycerol (OAG) on the immunocytochemical localization of protein kinase C in these cells. Indirect immunofluorescence techniques revealed the enzyme to be located in a diffuse cytosolic pattern, in the intact cells. When the cells were exposed to 100 nM TPA, the immunofluorescent staining was translocated from the cytoplasm to the plasma membrane. The translocation was protracted and staining on the membrane decreased in parallel with the Ca2+, phospholipid-dependent protein kinase activity. Treatment of the cells with 500 nM ionomycin caused an apparent translocation comparable with that seen with TPA, however, this translocation was transient and most of the cytosolic staining was within 60 min. We also found that 30 micrograms/ml OAG did not have significant effects on distribution of the staining, but rather acted synergistically on the translocation with the suboptimal concentration of 100 nM ionomycin. A similar synergism was also observed with 10 nM TPA and 100 nM ionomycin. These results obtained in situ provide evidence that intracellular Ca2+ and diacylglycerol regulate membrane binding of the enzyme in vivo.


Subject(s)
Calcium/pharmacology , Diglycerides/pharmacology , Glycerides/pharmacology , Leukemia, Megakaryoblastic, Acute/enzymology , Protein Kinase C/analysis , Tetradecanoylphorbol Acetate/pharmacology , Anti-Bacterial Agents/pharmacology , Cell Membrane/drug effects , Cell Membrane/enzymology , Cytoplasm/enzymology , Diglycerides/chemical synthesis , Ethers/pharmacology , Fluorescent Antibody Technique , Humans , Immunoassay , Immunohistochemistry , Ionomycin , Ionophores/pharmacology , Protein Kinase C/metabolism , Tumor Cells, Cultured
15.
Clin Exp Dermatol ; 34(7): 830-3, 2009 Oct.
Article in English | MEDLINE | ID: mdl-19438532

ABSTRACT

An evaluation was made of a fully automated index of psoriasis, termed Computer-assisted Area and Severity Index (CASI). This method requires taking digital photographs of the target skin area(s) with a colour reference marker, Casmatch. The CASI evaluates the severity of the psoriasis from the size and redness of the lesion(s). In five patients with mild psoriasis vulgaris mainly observed on their trunk, 18 photographs of the trunk were taken every 2 weeks. Three of the five patients [Psoriasis Area and Severity Index (PASI) of 3.0, 3.6 and 10.1, respectively] were treated with oral cyclosporin 3 mg/kg/day for 4 weeks. The mean +/- SD area of lesion selected by a dermatologist was 2.3 +/- 1.3% of the total skin area. This method achieved extraction performance for psoriasis of 72.1 +/- 19.4% for sensitivity and 97.4 +/- 2.0% for specificity. CASI correlated strongly with PASI (r = 0.92), but not with Skindex16 (r = 0.35). Although only erythema was evaluated, our preliminary results indicate that this method is capable of quantifying psoriasis lesions.


Subject(s)
Image Interpretation, Computer-Assisted/methods , Psoriasis/pathology , Severity of Illness Index , Calibration , Color , Cyclosporine/therapeutic use , Dermatologic Agents/therapeutic use , Humans , Photography/methods , Psoriasis/drug therapy , Sensitivity and Specificity
16.
J Phys Condens Matter ; 21(14): 146005, 2009 Apr 08.
Article in English | MEDLINE | ID: mdl-21825352

ABSTRACT

Magnetization study of a single crystal of Nd(2)Fe(14)Si(3) (with the rhombohedral Th(2)Zn(17)-type structure) reveals that the compound is a ferromagnet with a spontaneous magnetic moment of 32.3µ(B) per formula unit (at T = 2 K) and a Curie temperature equal to 495 K. The easy-magnetization direction lies close to the b-axis, tilting slightly towards the c-axis. (The b-axis [120] is not a high-symmetry direction in the crystallographic class D(3d).) The observed strong magnetic anisotropy is attributed almost entirely to the Nd sublattice, as concluded from comparison with a Y(2)Fe(14)Si(3) single crystal. A magnetic field applied along the c-axis induces a first-order spin reorientation transition at B(FOMP) = 20 T. In the process of magnetization the Nd and Fe sublattices behave as essentially non-collinear. This is manifest particularly in the downward curvature of the first (pre-FOMP) stage of the magnetization curve. It is proposed to regard this curvature as a validity criterion for the single-sublattice approximation.

17.
Radiat Prot Dosimetry ; 184(2): 179-188, 2019 Aug 01.
Article in English | MEDLINE | ID: mdl-30476336

ABSTRACT

To manage the equivalent doses for radiation workers, exposure inhomogeneity is an important factor in the decision-making process related to protection measures and additional monitoring. Our previous study proposed the methodology to evaluate the inhomogeneity of exposure quantitatively. In this study, we applied proposed method to five different types of actual exposure situations encountered in the nuclear industry. Two of them were conventionally characterized as homogeneous exposure, and the other three were conventionally characterized as inhomogeneous exposure. The evaluation of homogeneity exposure was conducted using Monte Carlo calculations with two simplified models, which were then verified with phantom experiments. Consequently, all of the evaluations reproduced the experimental results, implying that our proposed method would be applicable for actual work conditions in the nuclear industry. Furthermore, the two presumed homogeneous exposure situations were found to be rather inhomogeneous because of the contribution of positrons and the limited source region. The results also show that the worker's posture has an impact on the inhomogeneity rather than the energy of incident radiation in nuclear works. The investigation also implies that obtaining the information on the most probable posture of the exposed worker, as well as the existence of the weekly penetrating radiation such as ß± ray as a main source of exposure would be the key for more precise estimation.


Subject(s)
Extremities/radiation effects , Lens, Crystalline/radiation effects , Occupational Exposure/analysis , Phantoms, Imaging , Radiation Exposure/analysis , Radiation Monitoring/methods , Radiation Protection/methods , Humans , Monte Carlo Method , Nuclear Reactors , Radiation Dosage
18.
AJNR Am J Neuroradiol ; 40(6): 1029-1036, 2019 06.
Article in English | MEDLINE | ID: mdl-31048300

ABSTRACT

BACKGROUND AND PURPOSE: Conventional imaging frequently shows overlapping features between benign and malignant parotid neoplasms. We investigated dynamic contrast-enhanced MR imaging using golden-angle radial sparse parallel imaging in differentiating parotid neoplasms. MATERIALS AND METHODS: For this retrospective study, 41 consecutive parotid neoplasms were imaged with dynamic contrast-enhanced MR imaging with golden-angle radial sparse parallel imaging using 1-mm in-plane resolution. The temporal resolution was 3.4 seconds for 78.2 seconds and 8.8 seconds for the remaining acquisition. Three readers retrospectively and independently created and classified time-intensity curves as follows: 1) continuous wash-in; 2) rapid wash-in, subsequent plateau; and 3) rapid wash-in with washout. Additionally, time-intensity curve-derived semiquantitative metrics normalized to the ipsilateral common carotid artery were recorded. Diagnostic performance for the prediction of neoplasm type and malignancy was assessed. Subset multivariate analysis (n = 32) combined semiquantitative time-intensity curve metrics with ADC values. RESULTS: Independent time-intensity curve classification of the 41 neoplasms produced moderate-to-substantial interreader agreement (κ = 0.50-0.79). The time-intensity curve classification threshold of ≥2 predicted malignancy with a positive predictive value of 56.0%-66.7%, and a negative predictive value of 92.0%-100%. The time-intensity curve classification threshold of <2 predicted pleomorphic adenoma with a positive predictive value of 87.0%-95.0% and a negative predictive value of 76.0%-95.0%. For all readers, type 2 and 3 curves were associated with malignant neoplasms (P < .001), and type 1 curves, with pleomorphic adenomas (P < .001). Semiquantitative analysis for malignancy prediction yielded an area under the receiver operating characteristic curve of 0.85 (95% CI, 0.73-0.99). Combining time-to-maximum and ADC predicts pleomorphic adenoma better than either metric alone (P < .001). CONCLUSIONS: Golden-angle radial sparse parallel MR imaging allows high spatial and temporal resolution permeability characterization of parotid neoplasms, with a high negative predictive value for malignancy prediction. Combining time-to-maximum and ADC improves pleomorphic adenoma prediction compared with either metric alone.


Subject(s)
Image Interpretation, Computer-Assisted/methods , Magnetic Resonance Imaging/methods , Parotid Neoplasms/diagnostic imaging , Parotid Neoplasms/pathology , Adult , Aged , Aged, 80 and over , Contrast Media , Female , Humans , Male , Middle Aged , Parotid Neoplasms/classification , Retrospective Studies
19.
Scand J Trauma Resusc Emerg Med ; 27(1): 40, 2019 Apr 08.
Article in English | MEDLINE | ID: mdl-30961651

ABSTRACT

BACKGROUND: Out-of-hospital cardiac arrest (OHCA) affects some 275,000 individuals in Europe each year. Time from collapse to defibrillation is essential for survival. As emergency medical services (EMS) response times in Sweden have increased, novel methods are needed to facilitate early treatment. Unmanned aerial vehicles (i.e. drones) have potential to deliver automated external defibrillators (AED). The aim of this simulation study was to explore bystanders' experience of a simulated OHCA-situation where a drone delivers an AED and how the situation is affected by having one or two bystanders onsite. METHODS: This explorative simulation study used a mixed methodology describing bystanders' experiences of retrieving an AED delivered by a drone in simulated OHCA situations. Totally eight participants were divided in two groups of bystanders a) alone or b) in pairs and performed CPR on a manikin for 5 minutes after which an AED was delivered by a drone at 50 m from the location. Qualitative data from observations, interviews of participants and video recordings were analysed using content analysis alongside descriptive data on time delays during bystander interaction. RESULTS: Three categories of bystander experiences emerged: 1) technique and preparedness, 2) support through conversation with the dispatcher, and 3) aid and decision-making. The main finding was that retrieval of an AED as delivered by a drone was experienced as safe and feasible for bystanders. None of the participants hesitated to retrieve the AED; instead they experienced it positive, helpful and felt relief upon AED-drone arrival and were able to retrieve and attach the AED to a manikin. Interacting with the AED-drone was perceived as less difficult than performing CPR or handling their own mobile phone during T-CPR. Single bystander simulation introduced a significant hands-off interval when retrieving the AED, a period lasting 94 s (range 75 s-110 s) with one participant compared to 0 s with two participants. CONCLUSION: The study shows that it made good sense for bystanders to interact with a drone in this simulated suspected OHCA. Bystanders experienced delivery of AED as safe and feasible. This has potential implications, and further studies on bystanders' experiences in real cases of OHCA in which a drone delivers an AED are therefore necessary.


Subject(s)
Cardiopulmonary Resuscitation/methods , Decision Making , Defibrillators/supply & distribution , Electric Countershock/instrumentation , Emergency Medical Services/methods , Models, Theoretical , Out-of-Hospital Cardiac Arrest/therapy , Aged , Aged, 80 and over , Data Collection , Female , Humans , Incidence , Male , Manikins , Out-of-Hospital Cardiac Arrest/epidemiology , Sweden/epidemiology , Video Recording
20.
Appl Radiat Isot ; 134: 302-306, 2018 Apr.
Article in English | MEDLINE | ID: mdl-29102161

ABSTRACT

Absolute measurement by the 4πß-γ coincidence counting method was conducted by two photomultipliers facing across a plastic scintillator to be focused on ß ray counting efficiency. The detector was held with a through-hole-type NaI(Tl) detector. The results include absolutely determined activity and its uncertainty especially about extrapolation. A comparison between the obtained and known activities showed agreement within their uncertainties.

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