Galactic interstellar filaments as probed by LOFAR and Planck

Recent Low Frequency Array (LOFAR) observations at 115-175 MHz of a field at medium Galactic latitudes (centered at the bright quasar 3C196) have shown striking filamentary structures in polarization that extend over more than 4 degrees across the sky. In addition, the Planck satellite has released full sky maps of the dust emission in polarization at 353GHz. The LOFAR data resolve Faraday structures along the line of sight, whereas the Planck dust polarization maps probe the orientation of the sky projected magnetic field component. Hence, no apparent correlation between the two is expected. Here we report a surprising, yet clear, correlation between the filamentary structures, detected with LOFAR, and the magnetic field orientation, probed by the Planck satellite. This finding points to a common, yet unclear, physical origin of the two measurements in this specific area in the sky. A number of follow-up multi- frequency studies are proposed to shed light on this unexpected finding.Comment: 6 pages, 4 figures, accepted for publication in MNRAS Letter

Održivo upravljanje otpadom u lokalnim samoupravama i zaštićenim područjima u Republici Srbiji

Moderni način života i težnja ka što bržem tehnološkom razvoju stvaraju sve veće probleme vezane za količine i menadžment generisanim otpadom. Upravljanje otpadom predstavlja složeni proces usled konstantne opasnosti po životnu sredinu kroz zagađenje vazduha, vode i zemljišta, kao i zdravlje ljudi. Nedostatak informacija o količinama, sastavu i mestu nastajanja otpada otežava proces deponovanja i kategorizacije, kao i njegovu reciklažu ili ponovnu upotrebu. Industrijalizacijom i razvojem modernog društva i neracionalnim korišćenjem prirodnih resursa povećava se količina otpada, te se javlja i potreba za organizovanim pristupom ovom problemu. Za rešavanje ovih pitanja, između ostalog, neophodni su konstantan monitoring, sprovođenje zakonske regulative i povećanje javne svesti. Ovo se posebno odnosi na prikupljanje pouzdanih podataka o količinama generisanog otpada, te njegovom zbrinjavanju u okviru lokalnih samouprava i zaštićenih područja. U Republici Srbiji za sada ne postoji sistemski organizovano upravljanje otpadom. Međutim, postoji dugoročna strategija u oblasti zaštite životne sredine koja podrazumeva poboljšanje kvaliteta života stanovništva i očuvanje prirode, gde važno mesto zauzima i pravilno postupanje sa otpadom

Distribution and forms of iron in the vertisols of Serbia

Soil of arable land and meadows from the Ap horizon, taken from ten different localities, were investigated for different forms of Fe, including total (HF), pseudo-total (HNO3), 0.1 M HCl extractable and DTPA (diethylenetriaminepentaacetic acid)-extractable. A sequential fractional procedure was employed to separate the Fe into fractions: water soluble and exchangeable Fe (I), Fe specifically adsorbed with carbonates (II), reducibly releasable Fe in oxides (III), Fe bonded with organic matter (IV) and Fe structurally bonded in silicates (residual fraction) (V). The soil pH, cation exchange capacity, and size fractions (clay and silt) had a strongest influence on the distribution of the different forms of Fe. The different extraction methods showed similar patterns of the Fe content in arable and meadow soils. However, the DTPA iron did not correspond with the total iron, which confirms the widespread incidence of iron-deficiency in vertisols is independent of the total iron in soils. The amount of exchangeable (fraction I) and specifically adsorbed (II) iron showed no dependence on its content in the other fractions, indicating low mobility of iron in vertisols. The strong positive correlation (r = 0.812 and 0.956) between the content of iron in HNO3 and HF and its contents in the primary and secondary minerals (fraction – V) indicate a low content of plant accessible iron in the vertisol. The sequential fractional procedure was confirmed as suitable for accessing the content and availability of iron in the vertisols of Serbia

Plan integrisanog monitoringa kvaliteta zemljišta kao indikatora kvaliteta životne sredine u Novom Sadu

U radu je prikazan plan integisanog upravljanja životnom sredinom na primeru kontrole kvaliteta zemljišta u gradu Novom Sadu u Republici Srbiji. S obzirom da ima veoma povoljan geografski položaj, Novi Sad je grad gde se prepliću važni magistralni putevi, ima sve veći priliv stanovništva, kao i brzi razvoj industrije i poljoprivrede. Usled navedenih činjenica postoji i povećano zagađivanje vazduha, vode i zemljišta, kao i generisanje velike količine otpada. Pored parkova i devastiranih područja u okolini industrijskih zona, rasprostranjena poljoprivredna delatnost u prigradskim delovima, naročito je osetljiva na kvalitet zemljišta i obrnuto. U ovoj studiji analizirani su geografska pozicija i geomorfološke karakteristike područja grada, kao i vodeći ekološki problemi. Na osnovu datih činjenica predložen je integrisani monitoring jednog od indikatora kvaliteta životne sredine, kvalitet zemljišta. Predložena je mreža od ukupno 15 senzora za merenje pH vrednosti, vlage i temperature zemljišta na teritoriji grada. Podaci o kvalitetu zemljišta koji se na ovakav način dobijaju u realnom vremenu veoma značajni su za eliminisanje ili ublažavanje potencijalnih nepoželjnih posledica. Zahvaljujući brzom razvoju tehnologije primena senzorskih mreža sve više se koristi u modernim sistemima monitoringa i dostupna je za efikasno i ekonomski isplativo rešavanje problema zaštite životne sredine

Polarized point sources in the LOFAR Two-meter Sky Survey: A preliminary catalog

The polarization properties of radio sources at very low frequencies (h45m–15h30m right ascension, 45°–57° declination, 570 square degrees). We have produced a catalog of 92 polarized radio sources at 150 MHz at 4.′3 resolution and 1 mJy rms sensitivity, which is the largest catalog of polarized sources at such low frequencies. We estimate a lower limit to the polarized source surface density at 150 MHz, with our resolution and sensitivity, of 1 source per 6.2 square degrees. We find that our Faraday depth measurements are in agreement with previous measurements and have significantly smaller errors. Most of our sources show significant depolarization compared to 1.4 GHz, but there is a small population of sources with low depolarization indicating that their polarized emission is highly localized in Faraday depth. We predict that an extension of this work to the full LOTSS data would detect at least 3400 polarized sources using the same methods, and probably considerably more with improved data processing

Distribution of chromium, nickel, copper and zinc in the Al Zintan area, northwestern Libya

Global population is growing rapidly. As a result, increasingly large areas are being settled and farmed. This devastates soils and causes pollution by heavy metals and other components. Heavy metals in the environment originate from both natural and anthropogenic sources. Natural sources generally include rock weathering and the propagation of heavy metals, such as Cr and Ni, from ultrabasic rocks. These are natural processes that generally do not threaten human health. Anthropogenic sources include industry and inappropriate disposal of waste in the environment. In such cases concentrations of heavy metals can be harmful to people and other living beings. Al Zintan is a city located in northwestern Libya, on a plateau mainly built up of Cretaceous sediments. Since the 1980’s, nomadic population has rapidly been settling this area. As a result, a former part of the desert was transformed and is used for farming. Soil sampling at Al Zintan was conducted in 2017, across a 2×2 km grid. A total of 143 samples were collected from depths of about 30 cm. The samples weighed 2 to 2.5 kg and generally comprised sand with a clay component. A Niton Xl3t goldd+ instrument was used for chemical analyses, based on which GIS heavy-metal distribution maps were generated. The distribution of Cr, Ni, Cu and Zn is discussed on the paper

Polarization leakage in epoch of reionization windows – II. Primary beam model and direction-dependent calibration

Leakage of diffuse polarized emission into Stokes I caused by the polarized primary beam of the instrument might mimic the spectral structure of the 21-cm signal coming from the epoch of reionization (EoR) making their separation difficult. Therefore, understanding polarimetric performance of the antenna is crucial for a successful detection of the EoR signal. Here, we have calculated the accuracy of the nominal model beam of Low Frequency ARray (LOFAR) in predicting the leakage from Stokes I to Q, U by comparing them with the corresponding leakage of compact sources actually observed in the 3C 295 field. We have found that the model beam has errors of ≤10 per cent on the predicted levels of leakage of ∼1 per cent within the field of view, i.e. if the leakage is taken out perfectly using this model the leakage will reduce to 10−3 of the Stokes I flux. If similar levels of accuracy can be obtained in removing leakage from Stokes Q, U to I, we can say, based on the results of our previous paper, that the removal of this leakage using this beam model would ensure that the leakage is well below the expected EoR signal in almost the whole instrumental k-space of the cylindrical power spectrum. We have also shown here that direction-dependent calibration can remove instrumentally polarized compact sources, given an unpolarized sky model, very close to the local noise level