Quantum calorimeter is as precise as nature allows

30 Jan 2020

Hot topic: Measurements of tiny temperature changes could help monitor the workings of superconducting quantum computers. (Courtesy: Safa Hovinen, Merkitys)

How do you define the position of something that won’t stay still? This is the problem physicists face when they try to measure a system’s properties with such precision that quantum effects contribute a significant source of uncertainty. Whatever the variable, and however refined the instrument, there comes a point at which the signal is lost in the noise.

A quantum calorimeter developed by researchers at Finland’s Aalto University School of Science and Lund University, Sweden, defines this limit for an ideal thermometer by measuring fluctuations in the electron temperature of a copper nanowire. The team found that the intrinsic thermal noise in the wire is small enough for them to detect a single microwave photon. As well as enabling new experiments in quantum thermodynamics, the device could be used to make noninvasive measurements of quantum systems such as qubits in superconducting quantum computers.

Tuned ultrasound selectively disrupts the structure of cancer cells

24 Jan 2020

Low-intensity pulsed ultrasound, with frequency tuned to match target cells, can break apart cancer cells without harming healthy blood cells. (Courtesy: iStock/Mohammed Haneefa Nizamudeen)

Medical engineers have proven that the unique internal structure of cancer cells can make them vulnerable to vibrations from specific frequencies of ultrasound. These low-intensity pulsed ultrasound waves are a potentially safe therapy to target cancers of the blood.

High-intensity focused ultrasound is sometimes used to destroy cancer cells deep within tissues, but the thermal energy transmitted can also damage healthy cells at the ultrasound focus. Low-intensity pulsed ultrasound (LIPUS), on the other hand, doesn’t heat up cells but is used to mechanically modulate cells, for stimulating bone repair, for example.

ΠΡΟΝΥΜΦΗ ΚΟΥΝΟΥΠΙΟΥ (ΓΕΝΙΚΗ ΒΙΟΛΟΓΙΑ-ΕΝΤΟΜΟΛΟΓΙΑ)

                   

ΠΡΟΝΥΜΦΗ ΚΟΥΝΟΥΠΙΟΥ (ΓΕΝΙΚΗ ΒΙΟΛΟΓΙΑ-ΕΝΤΟΜΟΛΟΓΙΑ)

Nanomaterial-coated fabric destroys chemical warfare agents

20 Jan 2020 

Composites made from metal-organic frameworks can destroy nerve agents under relevant conditions. Courtesy: Journal of the American Chemical Society

A textile coated with metal-organic frameworks (MOFs) could make an efficient anti-nerve agent material, according to experiments by researchers at Northwestern University in the US. The MOFs, which are based on zirconium, could act as catalysts to degrade chemical warfare agents such as VX and soman (GD) much faster than existing technologies, which are based on activated carbon and metal-oxide blends. The composite material, which might be used in protective suits and face masks for soldiers on the battlefield, does not require liquid water to work either, as previously thought.

MOFs are periodic nanoporous crystalline frameworks made from metal ions or clusters coordinated to organic ligands. The high surface area that comes from their porous structure means that they can be used in a host of applications, from sensing to gas separation and storage and catalysis.

Ultra-flat graphene goes wrinkle-free

17 Jan 2020 

Protons penetrating the graphene film grown on copper. Courtesy: L Gao

A new technique to make ultra-flat, wrinkle-free films of graphene could pave the way for a host of applications, including graphene-based flexible electronics and high-frequency transistors. The technique works by introducing protons into the film as graphene is synthesized using chemical vapour deposition (CVD), and its inventors say that it might be extended to other two-dimensional materials such hexagonal boron nitride (h-BN) and the transition-metal dichalcogenides (TMDCs). It could also aid the development of hydrogen storage devices made from layered 2D structures.

Graphene – a 2D honeycomb of carbon atoms just one atom thick – boasts several unique electronic properties. In contrast to conventional semiconductors, which have an energy gap between the electron valence and conduction bands, graphene is a “zero-gap” semiconductor. This means its electron valence and conduction bands just touch each other. At the point of contact, the electrons move at near-ballistic speeds, and their behaviour is governed by the Dirac equation for relativistic electrons – hence the name “Dirac point” for this section of graphene’s band structure.

Linear defects.

Photon frequency doubler is controlled by light

21 Jan 2020

Doubling up: Georgia Tech researchers Kyu-Tae Lee (left) and Mohammad Taghinejad demonstrate frequency doubling on a slab of titanium dioxide using a red laser to create nonlinear effects with tiny triangles of gold. The blue beam shows the frequency-doubled light and the green beam controls the hot-electron migration. (Courtesy: Rob Felt/Georgia Tech)

A way of using light to convert a normal optical material into a frequency doubler has been developed by Mohammad Taghinejad and colleagues at the Georgia Institute of Technology. The technique could have a range of applications from creating all-optical information-processing devices to studying quantum-mechanical tunnelling.

Frequency doubling is an optical effect that occurs in spatially asymmetrical materials that have a second-order nonlinear susceptibility. Two photons with the same frequency can interact with the material and combine to form a single photon with twice the frequency of the original photons. While most crystalline materials do not have the appropriate asymmetry in the bulk, frequency doubling can occur at surfaces and interfaces. However, relying on these very thin regions is not ideal for creating practical devices.

Artificial intelligence reveals how light flows around nanoparticles

23 Jan 2020

Making connections: artificial intelligence has been used to predict how light flows around nanoparticles. (Courtesy: University of Southampton)

Artificial intelligence has been used to quickly and accurately model the 3D flow of light around arbitrarily shaped nanoparticles. Peter Wiecha and Otto Muskens at the University of Southampton in the UK demonstrated the modelling approach using a neural network that required just a single training procedure. Their technique could be used to design a wide range of optical devices that control the paths taken by light.

When light interacts with nanostructures that are smaller in size than the wavelength of the light, the result can be very different from how light interacts with larger structures and continuous media. The field of nanophotonics seeks to exploit this by designing nanoparticles with particular shapes and compositions with the aim of manipulating light in specific ways.

Forbidden nuclear transition sheds light on how some stars die

Forbidden nuclear transition sheds light on how some stars die

23 Jan 2020

Exploded star: the crab nebula is believed to have been created by the explosion of an intermediate-mass star. (Courtesy: NASA/ESA/ J Hester and A Loll, Arizona State University)

Intermediate-mass stars expire via thermonuclear explosions, rather than gravitational collapse, according to experiments and calculations done by an international team of astrophysicists led by Oliver Kirsebom at Dalhousie University in Canada. By measuring the rate of a “forbidden” nuclear decay that transforms fluorine-20 into neon-20, they were able to work out the rate at which neon-20 in a star will capture electrons in a stellar environment. This rate was much higher than previously thought, leading the team to conclude that such stars are more likely to expire in thermonuclear explosions.

ΤΑ ΚΟΥΝΟΥΠΙΑ

ΤΑ ΚΟΥΝΟΥΠΙΑ

Ο βιολογικός κύκλος του κουνουπιού αποτελείται από το αβγό, τα προνυμφικά στάδια (προνύμφη), τη νύμφη και τέλος το ακμαίο. Εκτός από το τελευταίο στάδιο (ακμαίο-το γνωστό ενοχλητικό κουνούπι που μας τσιμπά) όλα τα άλλα διαβιούν στο νερό.

Η διάρκεια του βιολογικού κύκλου των κουνουπιών εξαρτάται κυρίως από τη θερμοκρασία. Η διάρκεια της ζωής των ενηλίκων κουνουπιών (ακμαίων) εξαρτάται συνήθως από διάφορους παράγοντες όπως πχ θερμοκρασία, υγρασία, το φύλο του κουνουπιού και την εποχή του χρόνου. Τα αρσενικά ακμαία ζουν για περίπου μία εβδομάδα ενώ τα θηλυκά ζουν περισσότερο και ανάλογα με τους παραπάνω παράγοντες το διάστημα αυτό μπορεί να φτάσει έως και ένα μήνα. Τα κουνούπια, εκτός της όχλησης που προκαλούν, είναι οι φορείς αρκετών ασθενειών για τον άνθρωπο όπως ελονοσία (malaria), Δάγκειος αιμορραγικός πυρετός (dengue hemorrhagic fever), κίτρινος πυρετός (Yellow fever virus), τσικουνγκούνια (chikungunya) και ο ιός του Δυτικού Νείλου (West Nile virus). 

Ancient rings surrounding the Sun could have divided the solar system

16 Jan 2020

Stellar rings: an infrared image of rings around a star that was taken by ALMA. (Courtesy: ALMA/ESO/NAOJ/NRAO)

The clear divide between the inner and outer solar system is the legacy of a ring structure that existed a very long time ago in the planet-forming disc that surrounded the Sun. That is the conclusion of Ramon Brasser at Tokyo Institute of Technology and Stephen Mojzsis at the University of Colorado Boulder, who have combined computer simulations of Jupiter’s formation with observations of the discs surrounding young stars.

The solar system is clearly divided between the inner rocky planets and asteroids, and the outer gas giants – with the border between the two regions lying between Jupiter and the asteroid belt. This difference can be quantified in terms of carbon – with the element being much more abundant in the outer part of the solar system than it is in the inner rocky planets and asteroids. The difference is so stark that astronomers now widely believe that material in the newly-formed Sun’s planet-forming circumstellar disc was similarly divided in terms of its composition.

For some reason, carbon-rich material from the outer solar system has been prevented from migrating into the inner solar system. One explanation for this barrier is that it arose during formation of Jupiter. As the gas giant gathered mass, the theory proposes, it prevented carbon-rich dust and sub-metre “pebbles” from reaching the inner solar system.

‘Physical cryptography’ uses neutrons to compare nuclear warheads

26 Sep 2016 Hamish Johnston

No knowledge: the weapons-verification-technique set-up

A new technique for comparing physical objects – while keeping the composition of the objects secret – has been demonstrated by physicists in the US and Italy. Based on a scheme for cryptography, the method involves comparing how radiation is transmitted through two targets and could be used to verify the presence of nuclear weapons in warheads.

Future agreements on the control of nuclear weapons could require that all nuclear warheads be accounted for, including those in storage. This would rely on inspectors being able to tell a real nuclear warhead apart from a fake one. This is important because it would prevent a country from secretly stashing away some of its declared warheads and replacing them with fakes.

Lithium-6 enriched semiconductor is efficient detector of thermal neutrons

Lithium-6 enriched semiconductor is efficient 

detector of thermal neutrons15 Jan 2020 Hamish Johnston

Compact and efficient: prototype of a working, pocket-sized neutron detector made with semiconductor rich in lithium-6. (Courtesy: Northwestern University/Argonne National Laboratory)

A semiconductor material containing lithium-6 shows great promise for creating highly-efficient detectors of thermal neutrons. The 2D layered material was created and tested by scientists in the US and could someday be used in detectors at neutron scattering facilities – boosting the efficiency and spatial resolution of experiments. Devices based on the semiconductor material could also be developed as personal radiation monitors and have security applications such as detecting radioactive materials like plutonium.

Ascaris lubricoides (Ασκαρίδα η σκωληκοειδής)

Ascaris lubricoides (Ασκαρίδα η σκωληκοειδής)

Νηματώδης έλμινθας με παγκόσμια κατανομή. Εντοπίζεται κυρίως σε τροπικές χώρες όπου η θερμοκρασία και η υγρασία ευνοούν την εξέλιξή του. 

ΜΟΡΦΟΛΟΓΙΚΑ ΧΑΡΑΚΤΗΡΙΣΤΙΚΑ ΕΝΗΛΙΚΟΥ ΠΑΡΑΣΙΤΟΥ 

Οι ενήλικες έλμινθες είναι λευκού χρώματος ή κιτρινέρυθρες με κωνικά άκρα. 

Ο άρρην σκώληκας έχει σώμα κυλινδρικό με ραβδώσεις εγκάρσιες που το πίσω άκρο του διπλώνεται κοιλιακά (μήκος παρασίτου περίπου 15-20cm), ενώ το θήλυ εχει μεγαλύτερο μήκος (20-35cm) και το ουραίο άκρο είναι οξύ και ευθύ. Αυτό διευκολύνει την σύζευξη των παρασίτων. 

three-body calculations suggest how black holes get close enough to merge

07 Jan 2020

Getting close: artistic impression of merging black holes (Courtesy: SXS/CC BY-NC 3.0)

A statistical solution to the infamous three-body problem of classical physics could explain why the LIGO-Virgo gravitational-wave detectors have observed numerous black-hole mergers.

The three-body problem involves three classical objects (such as stars, planets or even black holes) orbiting and interacting with one another. In principle, the behaviour of a three-body system at a future time in its evolution is uniquely determined by the initial conditions of the system. However, infinitesimal changes in these initial conditions can accumulate over time to become huge differences in outcomes. As it is never possible to measure initial conditions with infinite precision, it is therefore never possible to use them to predict long-term outcomes – a signature of deterministic chaos.

A general closed-form solution of the three-body problem does not exist, but if the objects are very different in mass, the system can be approximated by two-body problems with small perturbations from the third object. Things become more daunting, however, when the three masses are similar. Now, astrophysicists in the US have built computer models of such “non-hierarchical” triple systems. Created by Nicholas Stone of the Hebrew University of Jerusalem (who did the work while at Columbia University in New York) and Nathan Leigh of University of Concepción in Chile, the simulations could help to explain why LIGO-Virgo have seen an abundance of gravitational-wave signals from merging black holes.

LIGO–Virgo claims another neutron-star merger 09 Jan 2020 Hamish Johnston

LIGO–Virgo claims another neutron-star merger

09 Jan 2020 Hamish Johnston

Gravitational waves from the merger of two neutron stars were observed by the LIGO Livingston detector on 25 April 2019 – according to an international team of astrophysicists in the LIGO and Virgo collaborations. This is the second time that a signal from such an event has been seen and the merger is puzzling astrophysicists because it appears to have created an object with “unusually high mass”.

In a paper that has been submitted to The Astrophysical Journal Letters, the researchers say that the merger occurred about 500 million light-years away. The above video is a simulation of the merger process and the gravitational waves it produced.

The signal (dubbed GW 190425) was not recorded by the LIGO Hanford detector, which was not operating at the time, nor was it detected by the Virgo detector.

Natural Ways To Get Rid Of Intestinal Worms In No Time

                 


Natural Ways To Get Rid Of Intestinal Worms In No Time

                     

Ascaris lumbricoides removal from patient intestine

Ascaris worms in CBD.MPG Dr. Rohullah Satari دوکتور روح الله ستاری

                 

Ascaris worms in CBD.MPG Dr. Rohullah Satar

20 cm Long Worm In The Humanirst Ever Recorded On Video Eye, F | India V...

   

20 cm Long Worm In The Humanirst Ever Recorded On Video Eye,

θηλυκό σκουλήκι ξυδιού ΓΕΝΙΚΗ ΒΙΟΛΟΓΙΑ

     

θηλυκό σκουλήκι ξυδιού ( ΓΕΝΙΚΗ ΒΙΟΛΟΓΙΑ )

Σκουλήκια ξυδιού

Σκουλήκια ξυδιού

Έχετε δει ποτέ ένα σκουλήκι ξυδιού σε ένα μπουκάλι ξίδι μηλίτη; Πιθανότατα όχι. Ίσως να εκπλαγείτε να μάθετε ότι τα μικροσκοπικά στρογγυλά σκουλήκια, που συνήθως ονομάζονται σκουλήκια ξυδιού (Turbairix aceti (Anguillula)). βρίσκονται στο μη επεξεργασμένο ξύδι και αποτελούν πρόβλημα για τους παραγωγούς ξυδιού. Δεν θα τα βρείτε στο ξύδι που πωλείται στο τοπικό σούπερ μάρκετ επειδή το ξύδι αυτό έχει παστεριωθεί. Στην πραγματικότητα, τα σκουλήκια ξυδιού δεν καταναλώνουν το ίδιο το ξύδι. μάλλον τρέφονται με τα βακτήρια ξιδιού που ζουν στο ξίδι μηλίτη.