A comment on 'Accurate spin axes and solar system dynamics'

In a recent paper, Edvardsson etal (2002) propose a new solution for the spin evolution of the Earth and Mars. Their results differ significantly with respect to previous studies, as they found a large contribution on the precession of the planet axis from the tidal effects of Phobos and Deimos. In fact, this probably results from the omission by the authors of the torques exerted on the satellites orbits by the planet's equatorial bulge, as otherwise the average torque exerted by the satellites on the planet is null.Comment: november 19, 200

The Calibration of Stromgren uvby-Hbeta Photometry for Late-Type Stars -- a Model Atmosphere Approach

We aim to test the power of theoretical calibrations based on a new generation of MARCS models by comparisons with observational photomteric data. We calculate synthetic uvby-Hbeta colour indices from synthetic spectra. A sample of 388 field stars as well as stars in globular clusters is used for a direct comparison of the synthetic indices versus empirical data and for scrutinizing the possibilities of theoretical calibrations for temperature, metallicity and gravity. We show that the temperature sensitivity of the synthetic (b-y) colour is very close to its empirical counterpart, whereas the temperature scale based upon Hbeta shows a slight offset. The theoretical metallicity sensitivity of the m1 index (and for G-type stars its combination with c1) is somewhat larger than the empirical one, based upon spectroscopic determinations. The gravity sensitivity of the synthetic c1 index shows a satisfactory behaviour when compared to obervations of F stars. For stars cooler than the sun a deviation is significant in the c1-(b-y) diagram. The theoretical calibrations of (b-y), (v-y) and c1 seem to work well for Pop II stars and lead to effective temperatures for globular cluster stars supporting recent claims by Korn et al. (2007) that atomic diffusion occurs in stars near the turnoff point of NGC 6397. Synthetic colours of stellar atmospheres can indeed be used, in many cases, to derive reliable fundamental stellar parameters. The deviations seen when compared to observational data could be due to incomplete linelists but are possibly also due to effects of assuming plane-parallell or spherical geometry and LTE

Exploring the genome-wide impact of estrogen receptor alpha and estrogen receptor beta in breast and colon cancer cells

Estrogen signaling is involved in the development and progression of breast cancer and is implicated to be protective in colon cancer. Estrogenic actions are conveyed through transcriptional regulation by ligand stimulated estrogen receptors (ERα and ERβ). ERα is upregulated in most breast cancers and is responsible for the proliferative effect of estrogen. ERβ on the other hand is usually downregulated, and studies indicate an antiproliferative function. Therapies targeting ERα are available and commonly used in the treatment of breast cancer. In the normal colonic epithelia, however, ERβ is the most abundant estrogen receptor and the suggested mediator of the protective effects of estrogen in colon cancer. The role of ERβ in breast cancer and colon cancer is not well understood. Thus, exploring the genome-wide impact and contribution of both receptors in estrogen responsive cancers would substantially help to identify novel therapeutic and preventive strategies for these cancers. In Paper 1, we examined differences in transcriptional regulation between ERα and ERβ in the breast cancer cell line T47D. We could show that ERβ often exhibited an opposing effect on ERα-regulated genes within proliferation and regulation of cell cycle. We also demonstrated a set of genes only regulated by ERβ, indicating that, despite the high homology between the two receptors, there are differences in their transcriptional targets. The fact that ERβ opposed ERα indicates that ERβ activation may be of value in the treatment of breast cancer. To further explore the transcriptional role of ERα in breast cancer, we performed large-scale analyses of microRNA in 24 hours estrogen treated ERα-expressing T47D cells, Paper II. However, we found no evidence of direct and rapid regulation of mature miRNAs by ERα. In Paper III, we studied ERβ gene regulation in colon cancer cells. We could show that ERβ-expressing xenografts grew significantly slower than those lacking ERβ. Further we demonstrated that ERβ induced a transcriptional response independently of ERα and induced inhibition of the proto-oncogene MYC and other G1-phase cell cycle genes. In Paper IV, we dissected the regulatory networks of ERβ-induced transcriptional changes in human colon cancer cells. The set of genes changed by ERβ varied in different colon cancer cell lines, however, corresponded to the same biological processes such as cell cycle regulation and kinase activity. In addition, we identified the ERβ-driven downregulation of the transcription factor PROX1 as a key mechanism behind a large proportion of the transcriptional changes. In Paper V, we studied the effect of long term expression of ERβ on the miRNA pool in SW480 colon cancer cells. While we could not show a direct and rapid effect of ERα on the miRNome, we showed that long term expression of ERβ did induce large changes in the miRNA pool in colon cancer cells. In particular, we found the oncogenic miR-17-92 cluster to be downregulated and proposed this to be a consequence of the ERβ-induced downregulation of MYC. In conclusion, we have shown that ERβ is antiproliferative in breast and colon cancer cells, both when co-expressed with ERα and alone, as well as identified key signaling pathways. We suggest that activation of ERβ will have a beneficial effect for treatment or prevention of estrogen dependent cancers

Characterization of human myeloid progenitors and their differentiation

All hematopoietic cells are derived from the hematopoietic stem cells (HSCs) in a continuous and dynamic process, regulated by a network of transcription factors in different combinations and extrinsic signals from growth factors (GFs) and other factors in the microenvironment. In the initial stages of hematopoiesis HSCs differentiate to progenitor cells with gradually more restricted lineage potential and according to the most accepted model the first restriction in developmental potential results in commitment to either the lymphoid or the myeloid branch, in the latter followed by commitment to the neutrophil/monocyte and erythrocyte/megakaryocyte lineages. The objective of this thesis was to further characterize early human myeloid development. As a first step we established a map over neutrophil and erythroid differentiation-associated changes both on the surface and in gene expression, using in vitro cultures of normal human bone marrow cells. This map identifies lineage-specific markers and describes the expression patterns of suggested crucial regulators of myeloid development. Next we found that the inclusion of the growth factor receptor (GFR) thrombopoietin receptor (TpoR) in a previously presented immunophenotype definition of the human common myeloid progenitor (CMP), granulocyte/monocyte progenitor (GMP) and megakaryocyte/erythrocyte progenitor (MEP), significantly improved the separation of MEPs (TpoR+) from CMPs. Furthermore, it was shown that even though the surface expression of GFRs on these progenitors coincides with the supposed regulating functions of the corresponding GFs, it cannot always be predicted by the gene expression. More specific studies of the proposed CMP revealed that this is a heterogeneous population, composed of a fraction of multipotent cells that are susceptible to extrinsic regulation of lineage fate and a fraction of lineage-polarized or committed cells, which differentiate along their respective lineages regardless of the presence or absence of different GFs. However, it has proven difficult to find surface markers that separate these functional subcompartments and it is possible that they only differ in their expression of transcription factors and other intrinsic molecules

SHOULD WE DIFFERENTIATE BETWEEN BUSINESS AND PRIVATE CUSTOMERS?

The literature on how customers make their service-provider choices largely distinguishes between private and business customers, and companies’ offerings have been separated accordingly. This study takes a closer look at the possible differences between these two customer categories. The results are explorative and based on both qualitative and quantitative studies focusing on customers’ actual behavior. The findings show that it is not only job-related aspects such as “being able to work” that influence business travel, and that private matters such as “time with the family” are clearly of equal significance in the choice situation. Price perception is important, but only when it is set against the appropriate social costs. The contradiction appears in the airlines’ offers to these customers, which are generally specifically job related. The results of the present study show that most business customers are, in fact, “private customers”.air travel, customer relationships, business-to-business relationships, preferences, choice, service

Evaluation of respiratory gating – dose sparing and set-up

Strålbehandling kan användas för att behandla olika cancerdiagnoser. Man vill då kunna rikta strålningen mot tumören medan så lite frisk vävnad som möjligt bestrålas. Olika studier visar att för patienter som behandlas med strålbehandling för cancer i vänster bröst är förekomsten av och dödligheten i olika hjärtsjukdomar högre än för de som behandlas med strålbehandling för cancer i höger bröst. Detta beror på den ökade stråldosen till hjärtat vid behandling av cancer i vänster bröst till följd av att hjärtat är placerat närmare vänster bröst än höger bröst. Ett sätt att minska stråldosen till hjärtat vid behandling av bröstcancer i vänster bröst är att använda andningsanpassad strålbehandling. Då får patienten andas in djupare än normalt under behandlingen efter en röst som säger ”andas in” och ”andas ut”. Bestrålningen sker bara när patienten andats in. Då är avståndet mellan bröstet och hjärtat som störst och på så sätt kan stråldosen till hjärtat minskas. I denna studie visas att genom att behandla patienter med vänstersidig bröstcancer med andningsanpassad strålbehandling kan stråldosen till hjärtat minskas med 46 %, vilket resulterar i en minskning av sannolikheten att dö i hjärtsjukdomar för dessa kvinnor. Innan strålbehandlingen får patienten göra en datortomografiundersökning, vilket är en form av röntgenundersökning som ger snittbilder av patienten i tre dimensioner. I dessa bilder planerar man sedan hur strålfälten ska gå för att få så bra fördelning av stråldosen till det område som ska behandlas samtidigt som man minimerar stråldosen till den friska vävnaden. Det är viktigt att patienten ligger likadant vid behandling som under datortomografin. Ligger patienten annorlunda leder det till att stråldosen inte hamnar på det område som det var tänkt vilket kan leda till bestrålning av riskorgan och att delar av behandlingsområdet inte får den stråldos det var tänkt. På grund av uppläggningsproceduren för de patienter som behandlas med andningsanpassad strålbehandling kommer de att ligga lite annorlunda vid varje behandling. Denna avvikelse i positioneringen är systematisk och påverkar samtliga tillfällen patienten behandlas och kan korrigeras med en korrektionsstrategi. Genom att använda en korrektionsstrategi kan man uppskatta den systematiska avvikelsen och korrigera för den. Om man inte använder någon korrektionsstrategi introducerar man stora systematiska positioneringsavvikelser genom att använda andningsanpassad strålbehandling, vilket påverkar dosfördelningen till behandlingsområdet och hjärtat. Det är därför viktigt att korrigera för dessa systematiska avvikelser. Denna studie visar att den allmänt vedertagna korrektionsstrategin inte är den optimala för de patienter som behandlas med andningsanpassad strålbehandling. En justering av denna korrektionsstrategi, som resulterar i en bättre positionering, föreslås istället användas för denna patientgrupp.Purpose: To evaluate the benefits of using respiratory gating for left-sided breast cancer in the form of dose-sparing and biological effects to the heart and to investigate the set-up deviations for patients treated with respiratory gating in order to find an optimal correction strategy for this group of patients. Materials and methods: Nineteen patients treated with respiratory gating for left-sided breast cancer using the Real-time Position Management system (RPM, Varian Medical Systems, Inc., Palo Alto, CA) were retrospectively enrolled in this study. All patients had been treated with breast conserving surgery and no nodes were irradiated. Two CT-scans were performed for all patients treated with respiratory gating, one during deep breathing and one during normal free breathing. Since the patients had been treated with respiratory gating, structure delineation and treatment plans had already been made in the gated CT image set. For evaluation of the dose sparing and radiobiological effect, structure delineation was carried out and individually optimized treatment plans were created also for conventional treatment. Comparable target coverage was the main criteria when creating the treatment plans. The relative seriality model was used to calculate the cardiac mortality probability for the two treatment techniques. For evaluation of the set-up deviations, orthogonal kilovolt set-up images were acquired at every fraction for 18 patients treated with respiratory gating and 17 patients treated conventionally for comparison. In total, 659 images were acquired and manually matched with digitally reconstructed radiographs reconstructed from the CT image sets. Calculations of the set-up deviations were made both with no correction strategy applied and with the currently used correction strategy. The effect of the set-up deviation on the absorbed dose distribution was investigated by simulations in the treatment planning system (Eclipse version 10, Varian Medical Systems, Inc., Palo Alto, CA) and measurements with a biplanar diode array. Results: The mean absorbed dose to the heart was decreased for all patients in this study using respiratory gating. The average mean absorbed dose to the heart was 2.6 Gy for conventional treatment and 1.4 Gy for respiratory gating, a reduction of 46 %. For the left anterior descending (LAD) coronary artery the average mean absorbed dose was 13.9 Gy for conventional treatment and 4.2 Gy for respiratory gating, a reduction of 70 %. These reductions are statistically significant (p<0.01). The average mean absorbed dose to the left lung was 5.8 Gy for both conventional treatment and respiratory gating. As a result of the dose sparing for the heart the cardiac mortality probability could be reduced from 0.58 % for conventional treatment to 0.05 % for respiratory gating. An overall mean systematic deviation (moverall), calculated as the mean deviation for all patients and all treatment fractions, of 6.0 mm in the anterior direction and 8.1 mm in the cranial direction was present for the patients treated with respiratory gating if no correction strategy was applied. This set-up deviation results in increased absorbed dose to the organs at risk (OAR) and affects the absorbed dose distribution to the target. If the currently used correction strategy was applied to the deviations, moverall was reduced to 1.1 mm in the anterior direction and 3.3 mm in the cranial direction. moverall can be further reduced if the AML factor is excluded from the current correction strategy. If this was done, the moverall was 0.5 mm in the posterior direction and 1.0 mm in the cranial direction. No difference in the random set-up error was seen between the patients treated with conventional treatment and respiratory gating. Conclusions: Significant dose-sparing to the heart and LAD can be achieved using respiratory gating without compromising the target coverage. As a result of this dose sparing, the cardiac mortality probability can be reduced. This was comparable with earlier results [10, 13]. If no correction strategy is used for respiratory gating large systematic set-up deviations will be present which would increase the absorbed dose to the OARs and affect the dose distribution to the PTV. By excluding the AML factor from the currently used NAL correction strategy, the set-up deviations for the patients treated with respiratory gating will be minimized