190 research outputs found
Evolutionary models of the optical component of the LMC X-1/Star 32 binary system
Calculations carried out to model the evolution of Star 32 under different
assumptions about the stellar wind mass-loss rate provide robust limits on the
present mass of the star. The obtained range is 31 to 35.5 Msun, which is in
very good agreement with the orbital solution of Orosz et al., namely 28.3 to
35.3 Msun. The initial mass of Star 32 had to be in the range 35 to 40 Msun and
the present age of the system is 3.7 to 4.0 Myr.Comment: accepted for publication in MNRA
Transformation of the security doctrine of Europe and the Central and Eastern Europe region in the presence of the year of open war in Ukraine
Next generation autonomous analytical platforms for remote environmental monitoring
The Marie Curie ATWARM (Advanced Technologies for Water Management) project aims at the development of technologies to treat and manage drinking water. Within the ATWARM project there are 16 scientist working on different technologie aspects and processes to clean water from pollutants. In order to successfully treat water one needs reliable and rapid information on the environment state and potential alarming events. This information needs to be available in real time. Utilizing wireless sensor networks is the key to obtaining such monitoring capabilities. In the ideal case, information is gathered by the remote sensors and transmitted to headquarters for analysis. Unfortunately, such devices that are available today are big, very expensive and need frequent maintenance. Therefore they are not suitable for large scale and remote deployment. In order to be able to build cheap, robust and autonomous sensors one needs to develop smart materials. These materials are capable of reacting to an external stimulus and perform their given task. Current research involves polymers that bend or actuate reversibly after irridation with light or in some cases after applying magnetic fields. Fluidic sensors (required in every type of water analysis) incorporating such material in a form of pumps and valves would require minimum power. The light can come from an inexpensive, low power drain LED diode and magnetic fields from permanent magnets.
The sensor system already developed at the National Centre for Sensor Research (NCSR), Dublin City University is capable of sampling, managing chemical reactants required for the chemical analysis, performing the analysis with light emitting diodes and transmitting the information through wireless means to the controller unit. However it is still quite bulky, batteries lasts for 2 weeks and the manufacturing cost is still high for mass deployment. By using the described smart materials this device is expected to function for up to 6 months without maintenance and projected costs are estimated at less than 100 euro.
This research brings together scientists from fields such as computer science, electronics, engineering, chemistry and material science. Working in such an environment is greatly improving one’s interdisciplinary skills and team spirit along with innovative thinking necessary when applying fundamental science in functional devices such as sensors. This research is a great opportunity and adventure for the involved people but also the technology being developed will greatly enhance our environment monitoring capabilities. Efficient and successful environment protection and successful water management is important in all aspects of life
Physical and mechanical properties of phosphonium based poly(ionic liquids)
Currently for applications in materials science, there is a growing interest in Ionogels i.e. polymers with ionic liquids (ILs) integrated such that they retain their specific properties within the polymer/gel environment. However one disadvantage of ionogels is the leaching of the IL in the liquid phase1. To overcome this, ‘poly (ionic liquids) PILs, are gaining momentum in the literature.
Interesting applications for the incorporation of PILs into polymers have been published such as ultrasensitive and selective chemiresistive CO2 sensors2, and potential applications in fuel cell technology as some reported PIL films, display very high ionic conductivities (exceeding 90 mS cm-1 at 100 oC and 75% relative humidity)3. However the range of possible monomeric IL structures is far greater than has so far been explored4
In recent years functional materials have been developed to respond to a wide variety of stimuli, but their use in practical macro-scale devices has been hindered by slow response times arising mainly due to the diffusion processes that typically govern polymer swelling/contraction. The scaling-down to microfluidic devices should improve response times, due to the improved surface-to-volume ratios of these actuators. At these dimensions, stimuli-responsive PIL materials could dramatically enhance the capabilities of micro-fluidic systems by allowing self-regulated flow control.
In this study we synthesis, characterise and photopattern a family of PILs, Tributyl 4-Vinylbenzylphosphonium ([P4,4,4,4VB]+ ), Trihexyl 4-Vinylbenzylphosphonium ([P6,6,6,4VB]+) and Trihexyl-allyl phosphonium [P6,6,6,allyl]+ cations coupled with commonly found anions in the ionic liquid literature (chloride, dicyanamide and bis(trifluoromethylsulfonyl)imide). As one might expect varying the anion of the PIL gave varying behaviour (thermal stability and electrochemically). The resulting polymer gels from the PILs also gave drastic mechanical stability differences. Finally the synthesised polymer gels have been photo-structured to submicron resolution as both planar and 3D patterns employing both single and multi- photon polymerisation (MPP) techniques. These materials will form a platform for the next generation of sensors & actuators currently being developed
Gravitational wave background from binary systems
Basic aspects of the background of gravitational waves and its mathematical
characterization are reviewed. The spectral energy density parameter
, commonly used as a quantifier of the background, is derived for an
ensemble of many identical sources emitting at different times and locations.
For such an ensemble, is generalized to account for the duration of
the signals and of the observation, so that one can distinguish the resolvable
and unresolvable parts of the background. The unresolvable part, often called
confusion noise or stochastic background, is made by signals that cannot be
either individually identified or subtracted out of the data. To account for
the resolvability of the background, the overlap function is introduced. This
function is a generalization of the duty cycle, which has been commonly used in
the literature, in some cases leading to incorrect results. The spectra
produced by binary systems (stellar binaries and massive black hole binaries)
are presented over the frequencies of all existing and planned detectors. A
semi-analytical formula for is derived in the case of stellar
binaries (containing white dwarfs, neutron stars or stellar-mass black holes).
Besides a realistic expectation of the level of background, upper and lower
limits are given, to account for the uncertainties in some astrophysical
parameters such as binary coalescence rates. One interesting result concerns
all current and planned ground-based detectors (including the Einstein
Telescope). In their frequency range, the background of binaries is resolvable
and only sporadically present. In other words, there is no stochastic
background of binaries for ground-based detectors.Comment: 30 pages, 16 figure
Stimuli responsive materials for sensors & actuators
Current flow control solutions in analytical platforms
have high power consumption and are prone to mechanical failure.
To scale down such analytical platforms and enable
them to be incorporated into wireless sensor networks one needs revolutionary flow manipulation solutions[1]. Such solutions may come in the form of stimuli responsive materials
Using Photodynamic Therapy to Estimate Effectiveness of Innovative Combined Diclofenac and Tazaroten Therapy of Disseminated Actinic Keratosis
Early diagnosis and therapy of precancerous lesions and malignant tumors belong to the most challenging tasks in modern medicine. Photodynamic diagnosis can help diagnose both precancerous lesions and early carcinoma. Actinic keratosis (AK) is the most common precancerous lesion of the skin. The available data show a high effectiveness of diclofenac in treating multifocal AK. We report a case of a 52-year-old woman who complained of multiple disseminated AK lesions predominantly on the lower limbs and trunk with a significant exacerbation within the last 6 months. Due to the spreading of disease and a high number of AK foci, as well as technical problems with visiting the hospital (PDT Laboratory), photodynamic therapy was not applied. The patient was treated for 2 months with a combination of local administration of 3% diclofenac and 0.1% tazaroten and 3% diclofenac only as a half side (left-right) comparison. The effects of therapy were later clinically evaluated and verified by means of photodynamic diagnosis (PDD) directly after therapy and at a follow-up examination 3 months later. The evaluation of treatment was blinded.Treatment with diclofenac only on the right side of the body resulted in clearing of 55% of all treated lesions, which increased to 60% three months after finishing therapy. On the left side of the body, where combined therapy (diclofenac 2 times daily on uneven dates and diclofenac once a day + tazaroten once a day on even dates) was used, 77.5% pathologic lesions disappeared, but this did not increase at follow up. The treatment of multifocal, disseminated AK is a difficult task and also burdensome for the patient due to side effects like scarring or burning and itching which occur during most therapies. Combined therapy with diclofenac and tazaroten supported by PDD may improve the effects of routine treatment of AK.</p
The formation of the double neutron star pulsar J0737--3039
We find that the orbital period (2.4 hours), eccentricity (0.09), dipole
magnetic field strength (6.9 x 10^9 Gauss) and spin period (22 ms) of the new
highly relativistic double neutron star system PSR J0737-3039 can all be
consistently explained if this system originated from a close helium star plus
neutron star binary (HeS-NS) in which at the onset of the evolution the helium
star had a mass in the range 4.0 to 6.5 M_sun and an orbital period in the
range 0.1 to 0.2 days. Such systems are the post-Common-Envelope remnants of
wide Be/X-ray binaries (orbital period ~ 100 to 1000 days) which consist of a
normal hydrogen-rich star with a mass in the range 10 - 20 M_sun and a neutron
star. The close HeS-NS progenitor system went through a phase of mass transfer
by Roche-lobe overflow at a high rate lasting a few times 10^4 years; assuming
Eddington-limited disk accretion onto the neutron star this star was spun up to
its present rapid spin rate. At the moment of the second supernova explosion
the He star had a mass in the range 2.3 to 3.3 M_sun and in order to obtain the
present orbital parameters of PSR J0737-3039 a kick velocity in the range 70 -
230 km/s must have been imparted to the second neutron star at its birth.Comment: accepted by MNRA
Using Photodynamic Therapy to Estimate Effectiveness of Innovative Combined Diclofenac and Tazaroten Therapy of Disseminated Actinic Keratosis
Early diagnosis and therapy of precancerous lesions and malignant tumors belong to the most challenging tasks in modern medicine. Photodynamic diagnosis can help diagnose both precancerous lesions and early carcinoma. Actinic keratosis (AK) is the most common precancerous lesion of the skin. The available data show a high effectiveness of diclofenac in treating multifocal AK. We report a case of a 52-year-old woman who complained of multiple disseminated AK lesions predominantly on the lower limbs and trunk with a significant exacerbation within the last 6 months. Due to the spreading of disease and a high number of AK foci, as well as technical problems with visiting the hospital (PDT Laboratory), photodynamic therapy was not applied. The patient was treated for 2 months with a combination of local administration of 3% diclofenac and 0.1% tazaroten and 3% diclofenac only as a half side (left-right) comparison. The effects of therapy were later clinically evaluated and verified by means of photodynamic diagnosis (PDD) directly after therapy and at a follow-up examination 3 months later. The evaluation of treatment was blinded.Treatment with diclofenac only on the right side of the body resulted in clearing of 55% of all treated lesions, which increased to 60% three months after finishing therapy. On the left side of the body, where combined therapy (diclofenac 2 times daily on uneven dates and diclofenac once a day + tazaroten once a day on even dates) was used, 77.5% pathologic lesions disappeared, but this did not increase at follow up. The treatment of multifocal, disseminated AK is a difficult task and also burdensome for the patient due to side effects like scarring or burning and itching which occur during most therapies. Combined therapy with diclofenac and tazaroten supported by PDD may improve the effects of routine treatment of AK.</p
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