Time resolved spectroscopy of dust and gas from extrasolar planetesimals orbiting WD 1145+017

Multiple long and variable transits caused by dust from possibly disintegrating asteroids were detected in light curves of WD 1145+017. We present time-resolved spectroscopic observations of this target with QUCAM CCDs mounted in the Intermediate dispersion Spectrograph and Imaging System at the 4.2-m William Herschel Telescope in two different spectral arms: the blue arm covering 3800-4025 {\AA} and the red arm covering 7000-7430 {\AA}. When comparing individual transits in both arms, our observations show with 20 {\sigma} significance an evident colour difference between the in- and out-of-transit data of the order of 0.05-0.1 mag, where transits are deeper in the red arm. We also show with > 6 {\sigma} significance that spectral lines in the blue arm are shallower during transits than out-of-transit. For the circumstellar lines it also appears that during transits the reduction in absorption is larger on the red side of the spectral profiles. Our results confirm previous findings showing the u'-band excess and a decrease in line absorption during transits. Both can be explained by an opaque body blocking a fraction of the gas disc causing the absorption, implying that the absorbing gas is between the white dwarf and the transiting objects. Our results also demonstrate the capability of EMCCDs to perform high-quality time resolved spectroscopy of relatively faint targets.Comment: 9 pages, 5 figures. Accepted to MNRA

Ex vivo analysis of local orientation of collagen fiber bundles in 3D in posterior horn human meniscus using micro-computed tomography

Abstract. Objective: Knee osteoarthritis (OA) is an increasingly relevant joint disease affecting mostly aged population in developed countries. However, there is currently no treatment for OA and increasing the knowledge of the disease with the help of micro-computed tomography (µCT) imaging could offer help in finding the solution. The objective of this thesis was to quantitatively analyze the microstructural organization of human posterior horn meniscus samples in 3D using hexamethyldisilazane (HMDS) based µCT imaging. In addition, this study aims to compare the local microstructural organization of meniscus between OA patients and healthy references. Method: We collected medial and lateral posterior horns of human menisci from 10 endstage medial compartment knee OA patients undergoing total knee replacement surgery and from 10 deceased donors without diagnosed knee OA to act as healthy reference. The posterior horns were dissected and fixed in formalin, dehydrated in ascending alcohol concentrations, treated with HMDS, and scanned with a desktop µCT. Furthermore, we performed local orientation analysis of collagenous microstructure in 3D to all samples, by calculating local structure tensors from greyscale gradients withing a selected integration window to determine the polar angle for each voxel. Moreover, distribution of angles and mean estimated average angles were statistically compared. Results: Collagen fiber bundles in HMDS-treated meniscal samples were depicted in 3D using µCT. In the quantitative local orientation analysis, medial OA had overall lowest orientation angles compared to all other groups: mean estimated differences versus medial OA were -24° [95%CI -31°, -18°] in medial donor, -25° [95%CI -34°, -15°] in lateral OA, and -25° [95%CI -35°, -16°] in lateral donor groups. Distribution and mean angles between lateral OA and lateral donor menisci were similar with a mean difference of 2°. Conclusions: In this study, we were able to quantitatively analyze collagen fiber bundles and their orientations in 3D in the posterior horn of human meniscus using HMDS-based µCT imaging. Furthermore, collagen disorganization increased in the medial OA meniscus, suggesting a relationship between collagenous microstructure disorganization and meniscus degradation.Ihmisen nivelkierukan takasarven kollageenisäiekimppujen kolmi-ulotteinen lokaaliorientaatioanalyysi mikrotietokonetomografian avulla. Tiivistelmä. Tarkoitus: Nivelrikko on yleinen sairaus vanhenevassa yhteiskunnassa, mutta sairauden monimuotoisuuden vuoksi sen hoitaminen on vaikeaa. Sairauden vahvempi ymmärtäminen voisi auttaa hoidon kehittämisessä sairautta vastaan. Tämän pro gradu -tutkielman tavoitteena oli analysoida kvantitatiivisesti ihmisen nivelkierukkanäytteiden mikrorakenteiden orientaatiota kolmiulotteisesti käyttäen heksametyylidisilatsaaniin (HMDS) perustuvaa näytteenkäsittelytekniikkaa mikrotietokonetomografiakuvantamisessa (µCT). Lisäksi tässä työssä verrataan kierukan lokaalimikrorakenneorganisaatiota nivelrikkoisten potilaiden ja terveiden verrokkien välillä. Menetelmä: Keräsimme mediaali- ja lateraalipuolen nivelkierukan takasarvet kymmeneltä nivelrikon loppuvaiheen potilaalta, joille tehtiin polven tekonivelleikkaus, ja 10 menehtyneeltä oikeuslääketieteen potilaalta, joilla ei ollut diagnosoitua polven nivelrikkoa. Nivelkierukoiden posterioriset sarvet leikattiin, käsiteltiin formaliinilla, kuivattiin nousevissa etanolipitoisuuksissa, käsiteltiin HMDS:llä ja kuvattiin µCT-laitteella. Lisäksi teimme näytteille kolmiulotteisen orientaatioanalyysin, jolla mitataan näytteiden kollageenisen mikrorakenteen orientaatiota. Analyysi laskee µCT-kuvien harmaasävygradienttien avulla jokaiselle vokselille paikallisen rakennetensorin, joiden purkamisesta saadaan laskettua vokselin anisotropian määrä ja sen pienimmän vektorin suunta. Pienin arvo ja sen suunta voidaan määrittää vokselin pääasialliseksi orientaatioksi. Kulmien jakautumista ja keskimääräisiä kulmia verrattiin tilastollisesti terveiden ja nivelrikkopotilaiden mediaali- ja lateraalipuolten välillä. Tulokset: Nivelkierukan kollageenikimput kuvattiin kolmiulotteisesti µCT:llä käyttäen HMDS-käsiteltyjä nivelkierukkanäytteitä. Kvantitatiivisessa orientaatioanalyysissä todettiin mediaalipuolen nivelrikkoisilla nivelkierukoilla yleisesti enemmän disorganisaatiota kaikkiin muihin ryhmiin verrattuna: mediaalipuolen nivelrikkoryhmässä orientaatioiden ero verrattuna mediaaliverrokkiryhmään oli -24° [95%CI -31°, -18°], -25° [95%CI -34°, -15°] verrattuna lateraalipuolen nivelrikkoryhmään ja -25° [95%CI -35°, -16°] verrattuna lateraalipuolen luovuttajaryhmän välillä. Lisäksi lateraalipuolen luovuttaja- ja lateraalipuolen nivelrikkoryhmän välillä kulmien jakauma ja keskiarvo olivat samanlaiset keskimäärisen eron ollessa 2°. Johtopäätökset: Tässä tutkimuksessa onnistuimme kuvaamaan ihmisen nivelkierukan kollageenikimput sekä kvantitatiivisesti analysoimaan niiden kolmiulotteista orientaatiota käyttäen HMDS-pohjaista µCT-kuvantamista. Lisäksi kollageenin disorganisaatio oli suurin mediaalipuolen nivelrikkoisessa nivelkierukassa, mikä viittaa kollageenisen mikrorakenteen disorganisaatioon ja nivelkierukan degeneraation väliseen vahvaan suhteeseen

Rayleigh scattering in the transmission spectrum of HAT-P-18b

We have performed ground-based transmission spectroscopy of the hot Jupiter HAT-P-18b using the ACAM instrument on the William Herschel Telescope (WHT). Differential spectroscopy over an entire night was carried out at a resolution of $R \approx 400$ using a nearby comparison star. We detect a bluewards slope extending across our optical transmission spectrum which runs from 4750 to 9250\AA. The slope is consistent with Rayleigh scattering at the equilibrium temperature of the planet (852K). We do not detect enhanced sodium absorption, which indicates that a high-altitude haze is masking the feature and giving rise to the Rayleigh slope. This is only the second discovery of a Rayleigh scattering slope in a hot Jupiter atmosphere from the ground, and our study illustrates how ground-based observations can provide transmission spectra with precision comparable to the Hubble Space Telescope.Comment: 11 pages, 9 figures, accepted for publication in MNRA

Focused echocardiography and lung ultrasound protocol for guiding treatment in acute heart failure

Aims There is little evidence-based therapy existing for acute heart failure (AHF), hospitalizations are lengthy and expensive, and optimal monitoring of AHF patients during in-hospital treatment is poorly defined. We evaluated a rapid cardiothoracic ultrasound (CaTUS) protocol, combining focused echocardiographic evaluation of cardiac filling pressures, that is, medial E/e' and inferior vena cava index, with lung ultrasound (LUS) for guiding treatment in hospitalized AHF patients. Methods and results We enrolled 20 consecutive patients hospitalized for AHF, whose in-hospital treatment was guided using the CaTUS protocol according to a pre-specified treatment protocol targeting resolution of pulmonary congestion on LUS and lowering cardiac filling pressures. Treatment results of these 20 patients were compared with those of a standard care sample of 100 patients, enrolled previously for follow-up purposes. The standard care sample had CaTUS performed daily for follow-up and received standard in-hospital treatment without ultrasound guidance. All CaTUS exams were performed by a single experienced sonographer. The CaTUS-guided therapy resulted in significantly larger decongestion as defined by reduction in symptoms, cardiac filling pressures, natriuretic peptides, cumulative fluid loss, and resolution of pulmonary congestion (P <0.05 for all) despite a shorter mean length of hospitalization. Congestion parameters were significantly lower also at discharge (P <0.05 for all), without any significant difference in these parameters on admission. The treatment arm displayed better survival regarding the combined endpoint of 6 month all-cause death or AHF re-hospitalization (log rank P = 0.017). No significant difference in adverse events occurred between the groups. Conclusions The CaTUS-guided therapy for AHF resulted in greater decongestion during shorter hospitalization without increased adverse events in this small pilot study and might be associated with a better post-discharge prognosis.Peer reviewe

KIC 10449976: discovery of an extreme-helium subdwarf in the Kepler field

Optical spectroscopy of the blue star KIC 10449976 shows that it is an extremely helium-rich subdwarf with effective temperature T=40000+/-300 K and surface gravity log g=5.3+/-0.1. Radial-velocity measurements over a five-day timescale show an upper variability limit of ~50+/-20 km/s. Kepler photometry of KIC 10449976 in both long and short cadence modes shows evidence for a periodic modulation on a timescale of ~3.9 days. We have examined the possibility that this modulation is not astrophysical but conclude it is most likely real. We discuss whether the modulation could be caused by a low-mass companion, by stellar pulsations, or by spots. The identification of any one of these as cause has important consequences for understanding the origin of helium-rich subdwarfs.Comment: Accepted by MNRA

EFFECT OF CARBON CONTENT ON THE PHASE TRANSFORMATION CHARACTERISTICS, MICROSTRUCTURE AND PROPERTIES OF 500 MPa GRADE MICROALLOYED STEELS WITH NONPOLYGONAL FERRITE MICROSTRUCTURES

The influence of C in the range of 0.011-0.043 wt-% on the phase transformation characteristics, mechanical properties andmicrostructure of Fe-2.0Mn-0.25Mo-0.8Ni-0.05Nb-0.03Ti steel was investigated. In the dilatometric experiments, it wasfound that a reduction in the C content increased the phase transformation temperatures, decreased the hardness andpromoted quasi-polygonal ferrite (QF) formation over granular bainitic ferrite (GBF) and bainitic ferrite (BF), but at the sametime the sensitivity of the phase transformation temperatures and hardness to cooling rates was reduced. Mechanical testingof laboratory hot rolled plates revealed that the targeted yield strength of 500 MPa was reached even in the steel withthe lowest C content (0.011wt-%). An increase in C content did not considerably increase the yield strength, although thetensile strength was more significantly increased. Impact toughness properties, in turn, were markedly deteriorated due to thisC content increment. Microstructural analysis of the hot rolled plates showed that an increase in C content decreased thefraction of QF and consequently increased the fraction of GBF and BF, as well as the size and fraction of C-enriched secondarymicroconstituents. In addition, the size of the coarsest crystallographic packets seemed to be finer in the low C steelwith QF dominated microstructure than in its higher C counterparts with higher fractions of GBF-BF, even thought theaverage crystallographic packet size was slightly finer in these higher C steels.Mechanical testing of the simulated CGHAZ’s showed that their toughness properties are not strongly dependenton C content, although there exists a general trend for toughness to slightly weaken with increasing C content. Itcould be concluded that HAZ toughness properties of these types of steels are acceptable. On the basis of dilatometricexperiments, mechanical testing and microstructural analysis it can be stated that a good combination of strength,toughness and weldability as well as microstructural stability can be reached in very low C steels with QF dominatedmicrostructures. Finally, an example of this type of microstuctural concept, which has been successfull