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1.
Life (Basel) ; 14(5)2024 May 09.
Article in English | MEDLINE | ID: mdl-38792629

ABSTRACT

INTRODUCTION: Non-infectious erythema, or Red Breast Syndrome (RBS), has been observed on the skin where acellular dermal matrix was implanted, although the exact cause is yet to be determined. PATIENTS AND METHODS: A total of 214 female patients underwent breast-conserving surgery (BCS) and volume replacement using diced acellular dermal matrix (dADM) for breast cancer between December 2017 and December 2018. After collecting and evaluating relevant clinical data, inflammation markers, along with NK cell status presented by IFN-γ secretion assay, were measured using ELISA. RESULTS: Nineteen patients (8.88%) presented with RBS after BCS and dADM use. A significant increase of platelet-to-lymphocyte ratio was noted in the non-RBS group (p = 0.02). Compared to the RBS group (p = 0.042), the WBC level of the non-RBS group showed significant decrease over time. Eosinophil counts increased significantly at follow-up but went up higher in the RBS group. Multivariate analysis showed preoperative chemotherapy significantly increased the hazard of RBS (OR 3.274, p = 0.047 and OR 17.098, p < 0.001, respectively). DISCUSSION: Though no causal relationship between RBS and immune status was proven, the results suggest an association between preoperative chemotherapy and RBS in addition to the possible role of eosinophilia in leading to eosinophilic dermatoses, which warrants further exploration and elucidation.

2.
Int J Mol Sci ; 25(8)2024 Apr 22.
Article in English | MEDLINE | ID: mdl-38674146

ABSTRACT

Even though some studies have shown possible clinical relationship between molecular subtypes and tumor infiltrating natural killer (NK) cells around tumors, there are few studies showing the clinical relevance of peripheral NK cell activity at diagnosis in female patients with invasive breast cancer. A total of 396 female invasive breast cancer patients who received curative surgical treatment from March 2017 to July 2021 were retrospectively analyzed. NK cell activation-induced interferon-gamma (IFN-γ) secretion measured by enzyme-linked immunosorbent assay was used to measure the activity of peripheral NK cells. Statistical analyses were performed to determine clinical relationships with major clinicopathologic parameters. Quadripartite NK cell activity measured by induced interferon-gamma showed significant relevance with staging and body mass index, and some of the inflammatory serological markers, namely N/L (neutrophil/lymphocyte), P/N (platelet/neutrophil), and P/L (platelet/lymphocyte), showed significantly different NK activity in each interval by univariate analysis. A binary subgroup analysis, setting the IFN-γ secretion cut-off at 100 pg/mL, showed that stage III was significantly increased and axillary lymph node metastasis positivity was increased in the group of IFN-γ < 100 pg/mL, and IFN-γ secretion decreased with an increasing N stage, increased BMI (body mass index), and decreased production of IFN-γ. Following this, the same binary analysis, but with the IFN-γ secretion cut-off at 250 pg/mL, also showed that secretion in stage III was increased in those concentrations with <250 pg/mL, axillary lymph node positivity appeared to be correlated, and BMI ≥ 30 increased in prevalence. Additional ANOVA post hoc tests (Bonferroni) were performed on some serological markers that tended to be somewhat inconsistent. By subgroup analysis with Bonferroni adjustment between the IFN-γ secretion and TNM stage, no significant difference in IFN-γ secretion could be identified at stages I, II, and IV, but at stage III, the IFN-γ secretion < 100 pg/mL was significantly higher than 250 ≤ IFN-γ secretion < 500 pg/mL or IFN-γ secretion ≥ 500 pg/mL. According to this study, stage III was significantly associated with the lowest IFN-γ secretion. Compared to a higher level of IFN-γ secretion, a lower level of IFN-γ secretion seemed to be associated with increased body mass index. Unlike when IFN-γ secretion was analyzed in quartiles, as the IFN-γ secretion fell below 100 pg/mL, the correlation between axillary lymph node positivity and increased N stage, increased BMI, and increased N/L and P/L, which are suggested poor prognostic factors, became more pronounced. We think a peripheral IFN-γ secretion test might be convenient and useful tool for pretreatment risk assessment and selecting probable candidates for further treatment such as immunotherapy in some curable but high-risk invasive breast cancer patients, compared to other costly assaying of tissue NK cell activity at diagnosis.


Subject(s)
Breast Neoplasms , Interferon-gamma , Killer Cells, Natural , Neoplasm Staging , Humans , Female , Interferon-gamma/metabolism , Breast Neoplasms/pathology , Breast Neoplasms/metabolism , Breast Neoplasms/immunology , Middle Aged , Killer Cells, Natural/metabolism , Killer Cells, Natural/immunology , Aged , Adult , Retrospective Studies , Body Mass Index , Lymphatic Metastasis
3.
Philos Trans A Math Phys Eng Sci ; 382(2271): 20230071, 2024 May 09.
Article in English | MEDLINE | ID: mdl-38522458

ABSTRACT

We look at what astronomy from the Moon might be like over the next few decades. The Moon offers the possibility of installing large telescopes or interferometers with instruments larger than those on orbiting telescopes. We first present examples of ambitious science cases, in particular ideas that cannot be implemented from Earth. After a general review of observational approaches, from photometry to high contrast and high angular resolution imaging, we propose as a first step a 1-metre-class precursor and explore what science can be done with it. We add a proposal to use the Earth-Moon system to test the quantum physics theory. This article is part of a discussion meeting issue 'Astronomy from the Moon: the next decades (part 2)'.

4.
Sensors (Basel) ; 23(13)2023 Jun 29.
Article in English | MEDLINE | ID: mdl-37447888

ABSTRACT

Internet of Things (IoT) architectures generally focus on providing consistent performance and reliable communications. The convergence of IoT, edge, fog, and cloud aims to improve the quality of service of applications, which does not typically emphasize energy efficiency. Considering energy in IoT architectures would reduce the energy impact from billions of IoT devices. The research presented in this paper proposes an optimization framework that considers energy consumption of nodes when selecting a node for processing an IoT request in edge-fog-cloud layered architecture. The IoT use cases considered in this paper include smart grid, autonomous vehicles, and eHealth. The proposed framework is evaluated using CPLEX simulations. The results provide insights into mechanisms that can be used to select nodes energy-efficiently whilst meeting the application requirements and other network constraints in multi-layered IoT architectures.


Subject(s)
Conservation of Energy Resources , Internet of Things , Autonomous Vehicles , Communication , Computer Systems
5.
Int J Mol Sci ; 23(5)2022 Feb 25.
Article in English | MEDLINE | ID: mdl-35269680

ABSTRACT

The anticancer effects of ruxolitinib and calcitriol against breast cancer were reported previously. However, the effect of ruxolitinib and calcitriol combination treatment on various molecular subtypes of breast cancer remains unexplored. In this study, we used MCF-7, SKBR3, and MDA-MB-468 cells to investigate the effect of ruxolitinib and calcitriol combination treatment on cell proliferation, apoptosis, cell cycle, and cell signaling markers, in vitro and in vivo. Our results revealed the synergistic anticancer effect of ruxolitinib and calcitriol combination treatment in SKBR3 and MDA-MB-468 cells, but not in MCF-7 cells in vitro, via cell proliferation inhibition, apoptosis induction, cell cycle arrest, and the alteration of cell signaling protein expression, including cell cycle-related (cyclin D1, CDK1, CDK4, p21, and p27), apoptosis-related (c-caspase and c-PARP), and cell proliferation-related (c-Myc, p-p53, and p-JAK2) proteins. Furthermore, in the MDA-MB-468 xenograft mouse model, we demonstrated the synergistic antitumor effect of ruxolitinib and calcitriol combination treatment, including the alteration of c-PARP, cyclin D1, and c-Myc expression, without significant drug toxicity. The combination exhibited a synergistic effect in HER2-enriched and triple-negative breast cancer subtypes. In conclusion, our results suggest different effects of the combination treatment of ruxolitinib and calcitriol depending on the molecular subtype of breast cancer.


Subject(s)
Breast Neoplasms , Triple Negative Breast Neoplasms , Animals , Apoptosis , Breast Neoplasms/metabolism , Calcitriol/pharmacology , Calcitriol/therapeutic use , Cell Line, Tumor , Cell Proliferation , Cyclin D1 , Female , Humans , Mice , Nitriles , Poly(ADP-ribose) Polymerase Inhibitors/pharmacology , Pyrazoles , Pyrimidines , Triple Negative Breast Neoplasms/pathology
6.
J Pharm Sci ; 110(10): 3457-3463, 2021 10.
Article in English | MEDLINE | ID: mdl-34126114

ABSTRACT

A new polymorphic form (Form C) of enantiopure Baclofen was isolated and characterized. Crystal structures of R-Baclofen Form A and Form C were resolved from powder diffraction data, and cell parameters by profile matching for Form B. The relative stability of these three forms is proposed based on structural data, thermal analyses and solvent-mediated conversions. The experiments highlight the stability order A < C < B at 25 °C (A is the most stable form), whereas above 180 °C it would likely be: C < A < B (C being the stable modification). Moreover, a new heterosolvate of the molecule is observed in N,N-DMF/water mixture. This heterosolvate offers a new pathway to isolate pure R-Baclofen Form B provided the lactam impurity does not exceed 3%. Upon mechanical stress Form B tends to evolve to Form C.


Subject(s)
Baclofen , Calorimetry, Differential Scanning , Crystallization , Powder Diffraction , X-Ray Diffraction
7.
Philos Trans A Math Phys Eng Sci ; 379(2188): 20200187, 2021 Jan 11.
Article in English | MEDLINE | ID: mdl-33222650

ABSTRACT

We address three major questions in astronomy, namely the detection of biosignatures on habitable exoplanets, the geophysics of exoplanets and cosmology. To achieve this goal, two requirements are needed: (i) a very large aperture to detect spectro-polarimetric and spatial features of faint objects such as exoplanets, (ii) continuous monitoring to characterize the temporal behaviour of exoplanets such as rotation period, meteorology and seasons. An Earth-based telescope is not suited for continuous monitoring and the atmosphere limits the ultimate angular resolution and spectro-polarimetrical domain. Moreover, a space telescope in orbit is limited in aperture, to perhaps 15 m over many decades. This is why we propose an OWL-class lunar telescope with a 50-100 m aperture for visible and IR astronomy, based on ESO's Overwhelmingly Large Telescope concept, unachievable on Earth for technical issues such as wind stress that are not relevant for a lunar platform. It will be installed near the south pole of the Moon to allow continuous target monitoring. The low gravity of the Moon will facilitate its building and manoeuvring, compared to Earth-based telescopes. We introduce a new original idea: such a large lunar telescope will allow Intensity Interferometric measurements when coupled with large Earth-based telescopes, leading to picosecond angular resolution. Rather than going into all details, our objective is essentially to inject new ideas and give a kind of roadmap. In particular, the choice of a final location will have to find a compromise between the cool temperature of craters at the Moon South Pole and the visibility of Earth for some science objectives. This article is part of a discussion meeting issue 'Astronomy from the Moon: the next decades'.

8.
Sensors (Basel) ; 20(19)2020 Oct 03.
Article in English | MEDLINE | ID: mdl-33023036

ABSTRACT

Continuous delivery has gained increased popularity in industry as a development approach to develop, test, and deploy enhancements to software components in short development cycles. In order for continuous delivery to be effectively adopted, the services that a component depends upon must be readily available to software engineers in order to systematically apply quality assurance techniques. However, this may not always be possible as (i) these requisite services may have limited access and (ii) defects that are introduced in a component under development may cause ripple effects in real deployment environments. Service virtualisation (SV) has been introduced as an approach to address these challenges, but existing approaches to SV still fall short of delivering the required accuracy and/or ease-of-use to virtualise services for adoption in continuous delivery. In this work, we propose a novel machine learning based approach to predict numeric fields in virtualised responses, extending existing research that has provided a way to produce values for categorical fields. The SV approach introduced here uses machine learning techniques to derive values of numeric fields that are based on a variable number of pertinent historic messages. Our empirical evaluation demonstrates that the Cognitive SV approach can produce responses with the appropriate fields and accurately predict values of numeric fields across three data sets, some of them based on stateful protocols.

9.
J Breast Cancer ; 23(3): 259-267, 2020 06.
Article in English | MEDLINE | ID: mdl-32595988

ABSTRACT

PURPOSE: Neoadjuvant chemotherapy (NAC) involving trastuzumab markedly increases pathologic complete response (pCR) rates in patients with human epidermal growth factor receptor 2-positive (HER2+) breast cancer. Despite increasing pCR rates, long-term survival gains are controversial owing to distinctive biologic behavior mediated by the presence of hormonal receptors (HRs) that may interact with HER2 receptors. We, therefore, investigated the differences in relative survival gain provided by neoadjuvant trastuzumab-based chemotherapy on HR positive (HR+) status of patients. METHODS: We retrospectively analyzed women with stage II or III HER2+ breast cancer who underwent NAC followed by a breast cancer surgery between 2008 and 2013. The survival benefits of adding trastuzumab to NAC were analyzed by classifying patients into HR+ and HR negative (HR-) groups. RESULTS: Of 666 patients included in the study, 374 (52.1%) were HR+ and 319 (47.9%) were HR-. In the HR+ group, trastuzumab treatment led to higher pCR rates and significantly better breast cancer specific survival (BCSS) and overall survival (OS) than no trastuzumab treatment. However, among patients with HR- breast cancer, trastuzumab treatment showed no statistically significant difference between BCSS and OS following multivariate analysis. CONCLUSION: We found that the addition of trastuzumab to NAC improved relative survival benefit in HER2+/HR+ patients than in HER2+/HR- patients, even though the pCR rate increases were lower. Although pCR has been regarded as a surrogate marker for estimating long-term survival benefits after NAC, it alone may not translate into real long-term oncologic outcomes in particular cancer subtypes after trastuzumab-based NAC. Further longer-term evaluation of the objective survival benefit after NAC driven by a dual HER2 block according to HR status is warranted.

10.
Mult Scler Relat Disord ; 43: 102146, 2020 Aug.
Article in English | MEDLINE | ID: mdl-32498033

ABSTRACT

BACKGROUND: Relapsing-remitting multiple sclerosis (RRMS) is frequently diagnosed in women of reproductive age. Because the use of disease-modifying therapies (DMTs) early in the disease course is increasing, it is important to evaluate the safety of DMTs in pregnant women and their developing fetuses. Alemtuzumab, approved for the treatment of relapsing forms of MS, is administered as 2 courses of 12 mg/day on 5 consecutive days at baseline and on 3 consecutive days 12 months later. Alemtuzumab is eliminated from the body within approximately 30 days after administration; it is recommended that women of childbearing potential use effective contraception during and for 4 months after treatment. Here, we report pregnancy outcomes in alemtuzumab-treated women from the phase 2 and 3 clinical development program over 16 years. METHODS: We followed 972 women who had alemtuzumab in phase 2 (CAMMS223 [NCT00050778]) and phase 3 (CARE-MS I [NCT00530348], CARE-MS II [NCT00548405]) studies, and/or in 2 consecutive extension studies (NCT00930553; NCT02255656 [TOPAZ]). In the extension studies, patients could receive additional alemtuzumab (12 mg/day on 3 days; ≥12 months apart) as needed for disease activity. All women who received alemtuzumab in the clinical development program were included. Pregnant or lactating patients were followed up for safety. RESULTS: As of November 26, 2018, 264 pregnancies occurred in 160 alemtuzumab-treated women, with a mean age at conception of 32.6 years, and mean time from last alemtuzumab dose to conception of 35.9 months. Of the 264 pregnancies, 233 (88%) were completed, 11 (4%) were ongoing, and 20 (8%) had unknown outcomes; 16 (6%) conceptions occurred within 4 months, and 5 conceptions within 1 month of the last alemtuzumab dose. Of the 233 completed pregnancies with known outcomes, there were 155 (67%) live births with no congenital abnormalities or birth defects, 52 (22%) spontaneous abortions, 25 (11%) elective abortions, and 1 (0.4%) stillbirth. Maternal age was associated with an increased risk of spontaneous abortion in alemtuzumab-treated patients (<35 years: 15%; ≥35 years: 37%; relative risk [RR], 2.46 [95% CI: 1.53-3.95], p=0.0002). Risk of spontaneous abortion was not increased in patients becoming pregnant ≤4 months versus >4 months since alemtuzumab exposure (19% vs 23%; RR, 1.08 [95% CI: 0.41-2.85], p=0.88). Autoimmune thyroid adverse events did not increase risk for spontaneous abortion (patients with vs without thyroid adverse events, 23.7% vs 21.3%; RR, 1.11 [95% CI: 0.69-1.80], p=0.75). Annualized relapse rate was 0.10 and 0.12 in the 2 years prior to pregnancy (post alemtuzumab), and was 0.22, 0.12, and 0.12 in each of the first 3 years postpartum, respectively. CONCLUSION: Normal live births were the most common outcome in women exposed to alemtuzumab 12 mg or 24 mg in clinical studies. Spontaneous abortion rate in alemtuzumab-treated patients was comparable with rates in the general population and treatment-naive MS patients, and was not increased in women with pregnancy onset within 4 months of alemtuzumab exposure. There was a minimal increase in postpartum relapses.


Subject(s)
Alemtuzumab , Antineoplastic Agents, Immunological , Multiple Sclerosis, Relapsing-Remitting , Pregnancy Outcome , Abortion, Spontaneous , Adult , Alemtuzumab/adverse effects , Antineoplastic Agents, Immunological/adverse effects , Female , Humans , Lactation , Multiple Sclerosis, Relapsing-Remitting/drug therapy , Pregnancy , Recurrence
11.
Sci Rep ; 10(1): 4149, 2020 03 05.
Article in English | MEDLINE | ID: mdl-32139743

ABSTRACT

Following recent tsunamis, most studies have focused on the onshore deposits, while the offshore backwash deposits, crucial for a better understanding of the hydrodynamic processes during such events and offering an opportunity for sedimentary archives of past tsunamis, have mostly been omitted. Here, we present a unique sedimentary record of the backwash from two historical tsunamis sampled in a sheltered bay in American Samoa, namely the 2009 South Pacific Tsunami and the 1960 Great Chilean Earthquake Tsunami. Although not always concomitant with a marked grain size change, backwash deposits are identified by terrestrial geochemical and mineralogical signatures, associated with basal soft sediment micro-deformations. These micro-deformations, including asymmetric flame structures, are described for the first time in historic shallow marine backwash deposits and lead us to propose an improved depositional mechanism for tsunami backflow based on hyperpycnal currents. Moreover, this study brings a potential new criterion to the proxy toolkit for identifying tsunami backwash deposits, namely the basal soft sediment micro-deformations. We suggest that further studies focus on these micro-deformations in order to test the representability of this criterion for tsunami backwash deposits. Sheltered shallow marine environments in areas repeatedly impacted by tsunamis have a higher potential for the reconstruction of paleo-tsunami catalogs and should be preferentially investigated for coastal risk assessment.

12.
Ann Surg Oncol ; 26(9): 2952-2958, 2019 Sep.
Article in English | MEDLINE | ID: mdl-31264119

ABSTRACT

BACKGROUND: Multifocal papillary thyroid microcarcinoma (PTMC) has been associated with poor outcomes; however, we often encounter pathologically confirmed unilateral multifocal PTMC after surgery. To date, no consensus on the proper surgical extent for patients with this form of PTMC has been reported. OBJECTIVE: The aim of this study was to analyze the effect of the type of surgical treatment on disease recurrence in patients with unilateral multifocal PTMC. METHODS: We retrospectively analyzed data from 255 patients with unilateral, multifocal, node-negative PTMC between March 1999 and December 2012. We evaluated two groups of patients: those who underwent unilateral lobectomy (Group I, n = 127) and those who underwent total thyroidectomy (Group II, n = 128). During the follow-up period, which lasted a median of 94.8 months, we assessed locoregional recurrence (LRR). RESULTS: There was no statistically significant difference between the two groups with regard to LRR at follow-up (3.15% for Group I vs. 0.78% for Group II; p = 0.244). The association between the type of surgical treatment and LRR remained nonsignificant after adjusting for potential confounders such as age, tumor size, microscopic extrathyroidal extension, and lymphovascular invasion (p = 0.115). During follow-up, the incidence of transient hypocalcemia (0% vs. 8.6%; p = 0.001) and vocal fold paralysis (1.6% vs. 9.4%; p = 0.011) was higher in Group II than in Group I. CONCLUSIONS: Even though randomized controlled trials are the only option to obtain a definitive answer to this question, unilateral lobectomy may be a safe operative option for selected patients with unilateral, multifocal, node-negative PTMC.


Subject(s)
Carcinoma, Papillary/surgery , Neoplasm Recurrence, Local/diagnosis , Thyroid Neoplasms/surgery , Thyroidectomy/classification , Thyroidectomy/mortality , Adult , Aged , Carcinoma, Papillary/pathology , Female , Follow-Up Studies , Humans , Incidence , Male , Middle Aged , Neoplasm Recurrence, Local/epidemiology , Prognosis , Republic of Korea/epidemiology , Retrospective Studies , Risk Factors , Survival Rate , Thyroid Neoplasms/pathology
13.
J Org Chem ; 79(3): 867-79, 2014 Feb 07.
Article in English | MEDLINE | ID: mdl-24437451

ABSTRACT

High-level electronic structure calculations, including a continuum treatment of solvent, are employed to elucidate and quantify the effects of alkyl halide structure on the barriers of SN2 and E2 reactions. In cases where such comparisons are available, the results of these calculations show close agreement with solution experimental data. Structural factors investigated include α- and ß-methylation, adjacency to unsaturated functionality (allyl, benzyl, propargyl, α to carbonyl), ring size, and α-halogenation and cyanation. While the influence of these factors on SN2 reactivity is mostly well-known, the present study attempts to provide a broad comparison of both SN2 and E2 reactivity across many cases using a single methodology, so as to quantify relative reactivity trends. Despite the fact that most organic chemistry textbooks say far more about how structure affects SN2 reactions than about how it affects E2 reactions, the latter are just as sensitive to structural variation as are the former. This sensitivity of E2 reactions to structure is often underappreciated.

14.
Sci Am ; 304(3): 20, 2011 Mar.
Article in English | MEDLINE | ID: mdl-21438481
15.
Astrobiology ; 10(1): 5-17, 2010.
Article in English | MEDLINE | ID: mdl-20307179

ABSTRACT

The direct detection of Earth-like exoplanets orbiting nearby stars and the characterization of such planets-particularly, their evolution, their atmospheres, and their ability to host life-constitute a significant problem. The quest for other worlds as abodes of life has been one of mankind's great questions for several millennia. For instance, as stated by Epicurus approximately 300 BC: "Other worlds, with plants and other living things, some of them similar and some of them different from ours, must exist." Demokritos from Abdera (460-370 BC), the man who invented the concept of indivisible small parts-atoms-also held the belief that other worlds exist around the stars and that some of these worlds may be inhabited by life-forms. The idea of the plurality of worlds and of life on them has since been held by scientists like Johannes Kepler and William Herschel, among many others. Here, one must also mention Giordano Bruno. Born in 1548, Bruno studied in France and came into contact with the teachings of Nicolas Copernicus. He wrote the book De l'Infinito, Universo e Mondi in 1584, in which he claimed that the Universe was infinite, that it contained an infinite amount of worlds like Earth, and that these worlds were inhabited by intelligent beings. At the time, this was extremely controversial, and eventually Bruno was arrested by the church and burned at the stake in Rome in 1600, as a heretic, for promoting this and other equally confrontational issues (though it is unclear exactly which idea was the one that ultimately brought him to his end). In all the aforementioned cases, the opinions and results were arrived at through reasoning-not by experiment. We have only recently acquired the technological capability to observe planets orbiting stars other than 6 our Sun; acquisition of this capability has been a remarkable feat of our time. We show in this introduction to the Habitability Primer that mankind is at the dawning of an age when, by way of the scientific method and 21(st)-century technology, we will be able to answer this fascinating controversial issue that has persisted for at least 2500 years.


Subject(s)
Atmosphere , Life , Planets , Research Design , Solar System , Humans , Time Factors
16.
Astrobiology ; 10(1): 19-32, 2010.
Article in English | MEDLINE | ID: mdl-20307180

ABSTRACT

To estimate the occurrence of terrestrial exoplanets and maximize the chance of finding them, it is crucial to understand the formation of planetary systems in general and that of terrestrial planets in particular. We show that a reliable formation theory should not only explain the formation of the Solar System, with small terrestrial planets within a few AU and gas giants farther out, but also the newly discovered exoplanetary systems with close-in giant planets. Regarding the presently known exoplanets, we stress that our current knowledge is strongly biased by the sensitivity limits of current detection techniques (mainly the radial velocity method). With time and improved detection methods, the diversity of planets and orbits in exoplanetary systems will definitely increase and help to constrain the formation theory further. In this work, we review the latest state of planetary formation in relation to the origin and evolution of habitable terrestrial planets.


Subject(s)
Gases , Planets , Solar System , Time Factors
17.
Astrobiology ; 10(1): 33-43, 2010.
Article in English | MEDLINE | ID: mdl-20307181

ABSTRACT

The problem of the stability of planetary systems, a question that concerns only multiplanetary systems that host at least two planets, is discussed. The problem of mean motion resonances is addressed prior to discussion of the dynamical structure of the more than 350 known planets. The difference with regard to our own Solar System with eight planets on low eccentricity is evident in that 60% of the known extrasolar planets have orbits with eccentricity e > 0.2. We theoretically highlight the studies concerning possible terrestrial planets in systems with a Jupiter-like planet. We emphasize that an orbit of a particular nature only will keep a planet within the habitable zone around a host star with respect to the semimajor axis and its eccentricity. In addition, some results are given for individual systems (e.g., Gl777A) with regard to the stability of orbits within habitable zones. We also review what is known about the orbits of planets in double-star systems around only one component (e.g., gamma Cephei) and around both stars (e.g., eclipsing binaries).


Subject(s)
Solar System , Jupiter , Planets
18.
Astrobiology ; 10(1): 77-88, 2010.
Article in English | MEDLINE | ID: mdl-20307184

ABSTRACT

After Earth's origin, our host star, the Sun, was shining 20-25% less brightly than today. Without greenhouse-like conditions to warm the atmosphere, our early planet would have been an ice ball, and life may never have evolved. But life did evolve, which indicates that greenhouse gases must have been present on early Earth to warm the planet. Evidence from the geological record indicates an abundance of the greenhouse gas CO(2). CH(4) was probably present as well; and, in this regard, methanogenic bacteria, which belong to a diverse group of anaerobic prokaryotes that ferment CO(2) plus H(2) to CH(4), may have contributed to modification of the early atmosphere. Molecular oxygen was not present, as is indicated by the study of rocks from that era, which contain iron carbonate rather than iron oxide. Multicellular organisms originated as cells within colonies that became increasingly specialized. The development of photosynthesis allowed the Sun's energy to be harvested directly by life-forms. The resultant oxygen accumulated in the atmosphere and formed the ozone layer in the upper atmosphere. Aided by the absorption of harmful UV radiation in the ozone layer, life colonized Earth's surface. Our own planet is a very good example of how life-forms modified the atmosphere over the planets' lifetime. We show that these facts have to be taken into account when we discover and characterize atmospheres of Earth-like exoplanets. If life has originated and evolved on a planet, then it should be expected that a strong co-evolution occurred between life and the atmosphere, the result of which is the planet's climate.


Subject(s)
Atmosphere/chemistry , Climate , Evolution, Planetary , Solar System , Oxygen/chemistry , Ozone/chemistry , Photosynthesis , Planets , Sunlight , Ultraviolet Rays
19.
Astrobiology ; 10(1): 69-76, 2010.
Article in English | MEDLINE | ID: mdl-20307183

ABSTRACT

The ultimate goal of terrestrial planet-finding missions is not only to discover terrestrial exoplanets inside the habitable zone (HZ) of their host stars but also to address the major question as to whether life may have evolved on a habitable Earth-like exoplanet outside our Solar System. We note that the chemical evolution that finally led to the origin of life on Earth must be studied if we hope to understand the principles of how life might evolve on other terrestrial planets in the Universe. This is not just an anthropocentric point of view: the basic ingredients of terrestrial life, that is, reduced carbon-based molecules and liquid H(2)O, have very specific properties. We discuss the origin of life from the chemical evolution of its precursors to the earliest life-forms and the biological implications of the stellar radiation and energetic particle environments. Likewise, the study of the biological evolution that has generated the various life-forms on Earth provides clues toward the understanding of the interconnectedness of life with its environment.


Subject(s)
Biological Evolution , Life , Planets , Environment , Ions , Solar System
20.
Astrobiology ; 10(1): 89-102, 2010.
Article in English | MEDLINE | ID: mdl-20307185

ABSTRACT

We discuss how to read a planet's spectrum to assess its habitability and search for the signatures of a biosphere. After a decade rich in giant exoplanet detections, observation techniques have advanced to a level where we now have the capability to find planets of less than 10 Earth masses (M(Earth)) (so-called "super Earths"), which may be habitable. How can we characterize those planets and assess whether they are habitable? This new field of exoplanet search has shown an extraordinary capacity to combine research in astrophysics, chemistry, biology, and geophysics into a new and exciting interdisciplinary approach to understanding our place in the Universe. The results of a first-generation mission will most likely generate an amazing scope of diverse planets that will set planet formation, evolution, and our planet into an overall context.


Subject(s)
Planets
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