Analyses of zonal atmospheric excitation functions and their correlation with polar motion excitation functions

International audienceThe atmospheric influence on the Earth's, rotation can be described by the effective atmospheric angular momentum (EAAM) functions. In this study we focus on the analysis of short period variations of the equatorial components of the zonal EAAM excitation functions ?1 and ?2 and their influence on similar variations of polar motion. The global objective analysis data of the Japanese Meteorological Agency for the period 1986?1992 were used to compute the EAAM excitation functions in different latitude belts. Time- and latitude-variable amplitude spectra of variations of these functions with periods shorter than 150 days, containing pressure, pressure with the inverted barometric correction, and wind terms were computed. The spectra show distinct latitude and time variations of the prograde and retrograde oscillations which reach their maxima mainly in mid-latitudes. Prograde and retrograde oscillations with periods of about 40?60 days and about 110?120 days are seen in the spectra of pressure terms of the equatorial components of the zonal EAAM excitation functions. Additionally, correlation coefficients and cross-spectra between variations of the geodetic polar motion and equatorial components of the zonal EAAM excitation functions were computed to identify the latitude belts of the globe over which atmospheric circulation changes are correlated mostly with short period variations of the polar motion excitation functions. The correlation coefficients vary in time and latitude and reach maximum values in the northern latitudes from 50°N to 60°N. In the cross-spectra between the polar motion excitation functions and pressure terms of the zonal EAAM excitation functions there are peaks of common prograde oscillations with the periods around 20, 30, 40?50, 60 and 80?150 days and of common retrograde oscillations around 20, 30, 40 and 50?70 days

Development of convection along the SPCZ within a Madden-Julian oscillation

A subtropical Rossby wave propagation mechanism is proposed to account for the poleward and eastward progression of intraseasonal convective anomalies along the South Pacific Convergence Zone (SPCZ) that is observed in a significant proportion of Madden-Julian Oscillations (MJOs). Large scale convection, associated with an MJO, is assumed to be already established over the Indonesian region. The latent heating associated with this convection forces an equatorial Rossby wave response with an upper tropospheric anticyclone, centred over or slightly to the west of the convection. Large potential vorticity (PV) gradients, associated with the subtropical jet and the tropopause, lie just poleward of the anticyclone and large magnitude PV air is advected equatorwards on the eastern side of the anticyclone. This ``high'' PV air, or upper tropospheric trough, is far enough off the equator that it has associated strong horizontal temperature gradients, and it induces deep ascent on its eastern side, at a latitude of about 15-30\degr. If this deep ascent is over a region susceptible to deep convection, such as the SPCZ region, then convection may be forced or triggered. Hence convection develops along the SPCZ as a forced response to convection over Indonesia. The response mechanism is essentially one of subtropical Rossby wave propagation. This hypothesis is based on a case study of a particularly strong MJO in early 1988, and is tested by idealised modelling studies. The mechanism may also be relevant to the existence of the mean SPCZ, as a forced response to mean Indonesian convection

Observations of Stratospheric Sudden Warmings in Earth Rotation Variations

Stratospheric sudden warmings (SSWs) are extreme events in the polar stratosphere that are both caused by and have effects on the tropospheric flow. This means that SSWs are associated with changes in the angular momentum of the atmosphere, both before and after their onset. Because these angular momentum changes are transferred to the solid Earth, they can be observed in the rate of the Earth's rotation and the wobble of its rotational pole. By comparing observed Earth rotation variations to reanalysis data, we find that an anomaly in the orientation of the Earth's rotational pole, up to 4 times as large as the annual polar wobble, typically precedes SSWs by 20-40 days. The polar motion signal is due to pressure anomalies that are typically seen before SSW events and represents a new type of observable that may aid in the prediction of SSWs. A decline in the length of day is also seen, on average, near the time of the SSW wind reversal and is found to be due to anomalous easterly winds generated in the tropical troposphere around this time, though the structure and timing of this signal seems to vary widely from event to event

Empirische Basis zum voraussagen des Erfolgs Inkampfsportarten und in der Selbstverteidigung

The aim of the study was to find out whether being superior to the opponent with respect to physical fitness would be a prerequisite for success in a hand-to-hand struggle, and whether it would apply to those who had no experience in such contests, as well as to those who had been trained for at least a year. The so-called International Fitness Test was used to assess the level of fitness, and the combat performance was determined by using two types of contests: according to a modified sumo formula (in a vertical position) or according to the judo formula (in a horizontal position). All contests were conducted in the round-robin system. It was found that physical fitness superiority over an opponent was no prerequisite for success in a hand-to-hand struggle. Owing to the methodological and organisational simplicity of the test contests in sumo, as well as to a very high correlation between the results of sumo and judo (ne waza, in a horizontal position) contests (r = 0.892), the sumo contests may serve as a specific tool for measuring competence in hand-to-hand struggles.Uvod Jedno od temeljnih pitanja sportske znanosti jest pitanje utvrđivanja pouzdanoga kriterija za se-lekciju sportaša. U okviru selekcije talentiranih po-jedinaca za borilačke sportove primjenjuju se razli-čite metode. U dosadašnjim se istraživanjima pokazalo da početak treninga juda u ranoj dobi nije nužan preduvjet za vrhunska postignuća. Identificirane su motoričke sposobnosti važne za uspjeh u judu, hrvanju, tae kwon dou i ostalim borilačkim sportovima, a brojni su se radovi bavili procjenom statusa specifične pripremljenosti, kao i relacijama psihološkog i intelektualnog statusa s natjecateljskom uspješnošću. Neki su autori smatrali ključnim natjecateljsko iskustvo (broj sportova u kojima je pojedinac sudjelovao i razina postignuća), drugi daju prednost odabiru talentiranih na temelju iskustva u borilačkim sportovima, na temelju uloženog napora i natjecateljskih opterećenja. Postojeća literatura daje dobar pregled načina rada i savjeta kako poboljšati sustav treninga i pripreme u borilačkim sportovima i samoobrani, no informacije o preciznim selekcijskim kriterijima za ovo područje (sport ili posao, kao primjerice u policiji, vojsci i sigurnosnim službama i dr.) nedostaju. Komercijalizacija sporta mnogim trenerima (ali i znanstvenicima) daje priliku da se pozabave područjem selekcije. Iskustva iz prakse pokazuju da mnogi treneri za selekciju koriste najjednostavnije kriterije, uglavnom utemeljene na motoričkim sposobnostima. Takav pristup proizlazi iz nedovoljne upućenosti u područje, čak i iz pogrešnog predznanja. Naime, norme su prilagođene različitim kategorijama, što se rijetko uzima u obzir, pa se biraju snažniji, agilniji, izdržljiviji i slično, što odgovara većini sportova, no ne nužno uvijek i svima (npr. judu). Cilj ovog rada jest provjeriti postavku o tome kako tjelesni status (superiornost) nije apsolutni preduvjet za pobjeđivanje protivnika u izravnoj borbi ni u stojećem stavu ni na tlu. Postavka će se provjeriti na ispitanicima koji nemaju iskustva u borbi i na sportašima borilačkih sportova. Metode Provedena su četiri ispitivanja, a u svakome je korištena specifična istraživačka tehnika kako bi se odgovorilo na problem. Ispitivanje 1 provedeno je radi utvrđivanja povezanosti opće tjelesne pripremljenosti s ishodima borbe u judu u stojećem stavu. Ispitana su 22 dječaka u dobi od 11 godina, tjelesne mase 20,5 do 39,5 kg koji su se borili u okviru 6 timova oblikovanih prema tjelesnoj težini. Ispitivanje 2 provjeravalo je povezanost dobi, tjelesne mase i ishoda borbe u judu u stojećem stavu na uzorku od 21 dječaka, početnika u judu. Dob ispitanika bila je 7 do 13 godina, a težina je varirala između 22 i 44,6 kg. Formirano je 6 natje-cateljskih timova. Ispitivanje 3 provjerilo je povezanost dobi, tjelesne mase i ishoda borbe u judu u stojećem stavu na uzorku profesionalnih tjelesnih čuvara ili kandidata za taj posao. Ispitano je 113 muškaraca u dobi od 19 do 43 godine, tjelesne mase od 67 do 125 kg. Formirana su 23 natjecateljska tima. Ispitivanje 4 istražilo je povezanost dobi, tjelesne mase i ishoda borbe u judu u stojećem stavu i na tlu na uzorku vojnika. Također je utvrđena povezanost ishoda oba tipa borbe. Ispitana su 33 kadeta, dobi od 19 do 21 godine, tjelesne mase od 58 do 96 kg. Oblikovana su dva tima. Tjelesna pripremljenost ispitana je baterijom od 8 motoričkih i funkcionalnih testova. Ishod borbe u stojećem stavu utvrđen je pomoću modificirane sumo formule na temelju 4 pobjede. Ukupna natjecateljska efikasnost definirana je pomoću tri indeksa: rang u pripadajućem timu, indeks natjecanja i indeks borbe. Ishod borbe na tlu utvrđen je pomoću formule juda u kružnom sustavu borbe do postignute tri pobjede. Izračunati su keoficijenti korelacija između utvrđenih mjera. Rezultati i rasprava Dobiveni rezultati pokazuju da superiornost nad protivnikom u tjelesnoj pripremljenosti nije preduvjet za uspjeh u borbi prsa o prsa. Povezanost ranga pojedinca unutar grupe i tjelesne pripremljenosti, utvrđene baterijom motoričkih i funkcionalnih testova, potvrđena je samo kod ispitanika koji su sudjelovali u prvom i četvrtom ispitivanju. Međutim, tjelesna pripremljenost nije se pokazala povezanom s pokazateljima efikasnosti natjecanja. Postoji povezanost između tjelesne mase i ishoda natjecanja, a dodatno se pokazalo da parcijalizacija tjelesne mase utječe na smanjenje povezanosti ishoda sumo i judo borbe kod kadeta. Kod djece se takav rezultat treba oprezno tumačiti, budući da su razlike njihovih pozicija u grupi znatno manje. Na temelju rezultata čini se da je adekvatna psihomotorna kompetentnost (‘talent’) važniji preduvjet pobjede u borbi kod djece. Judaši juniori nisu se pokazali nužno inferiornim vojnim kadetima s obzirom na njihovoj dobi odgovarajuću tjelesnu pripremljenost. Dobivene su visoke korelacije između pokazatelja uspješnosti sumo i judo borbe vojnih kadeta, no tjelesna pripremljenost nije statistički značajno povezana s uspjehom u sumu, dok je umjereno povezana s uspjehom u judu. Parcijalizacija tjelesne pripremljenosti nije utjecala na veličinu povezanosti ishoda sumo i judo borbe. Zaključak Dobiveni su rezultati važni u inicijalnim fazama judaškog treninga, kao i u treningu samoobrane svakog dobrovoljca, neovisno o dobi. Može se reći da borbe provedene prema modificiranoj sumo formuli ne zahtijevaju prethodan trening i mogu se provoditi među djecom i u ranoj školskoj dobi. S obzirom na metodološke prednosti i jednostavnost organiziranja sumo borbe te uz činjenicu visoke povezanosti ishoda sumo i judo borbe na tlu, sumo natjecanja mogu poslužiti kao specifičan test sposobnosti za borbu prsa o prsa.Das Ziel dieser Forschungsstudie war festzustellen, ob eine bessere körperliche Leistungsfähigkeit im Vergleich zum Gegner eine Voraussetzung für den Erfolg in einem modifizierten Sumo-Wettkampf ist, und ob das auch für die ohne jegliche Erfahrung in Wettkämpfen gilt, sowie für diejenigen, die mindestens ein Jahr trainierten. Der Internationale Fitness Test wurde angewandt, um den Fitnessgrad zu bestimmen, während die Kampfleistung mittels zwei Wettkampftypen bewertet wurde: nach der modifizierten Sumo-Formel (in senkrechter Position) oder nach der Judo-Formel (in waagerechter Position). Alle Kämpfer traten mit jedem Gegner zum Kampf an. Es wurde gezeigt, dass eine bessere körperliche Leistungsfähigkeit keine Voraussetzung für den Erfolg in einem modifizierten Sumo-Wettkampf darstellt. Da die Sumo-Wettkampf-Tests in methodologischer und organisatorischer Hinsicht einfacher sind und da eine sehr hohe Korrelation zwischen den Sumo- und Judo- (ne waza, in waagerechter Position) Wettkampfergebnissen (r = 0,892) besteht, können Sumo-Wettkämpfe als ein spezifisches Mittel zur Kompetenzbewertungen in allen Kampfsportarten und Selbstverteidigung dienen

The impact of structural modification on the electrochromic and electroluminescent properties of D–A–D benzothiadiazole derivatives with a fluorene linker and (Bi)thiophene units

Two donor–acceptor–donor (D–A–D) derivatives of benzothiadiazole (BTD) symmetrically functionalized with dihexylfluorene units serving as a linker between the BTD core and the thiophene (Th-FBTD) or bithiophene (2Th-FBTD) electron-donating groups were designed, synthesized and comprehensively characterized. Both compounds show high photoluminescence quantum yield (PLQY) both in solution and in the solid state. Th-FBTD demonstrates PLQY values of 82% and 96%, whereas 2Th-FBTD exhibits values of 74% and 97% in DCM and Zeonex, respectively. These compounds were employed as emissive dopants in multilayer solution-processed OLEDs, resulting in green electroluminescence with an emission peak at ca. 540 nm. The OLEDs display comparable performance, with a maximum external quantum efficiency of 3.5% for Th-FBTD and 2.8% for 2Th-FBTD. Both Th-FBTD and 2Th-FBTD undergo quasi-reversible electrochemical reduction and irreversible oxidation, giving stable electroactive polymer layers of bipolar character: p(Th-FBTD) and p(2Th-FBTD). The electrodeposited polymers undergo one-step reversible reduction and two-step reversible oxidation. Their electrochemical oxidation is accompanied by a reversible color change. Analysis of the optical density difference and coloration efficiency revealed improved electrochromic properties in both visible and near-infrared (NIR) ranges in p(2Th-FBTD) compared to that in p(Th-FBTD)

Status of Women in Astronomy: A need for advancing inclusivity and equal opportunities

Women in the Astronomy and STEM fields face systemic inequalities throughout their careers. Raising awareness, supported by detailed statistical data, represents the initial step toward closely monitoring hurdles in career progress and addressing underlying barriers to workplace equality. This, in turn, contributes to rectifying gender imbalances in STEM careers. The International Astronomical Union Women in Astronomy (IAU WiA) working group, a part of the IAU Executive Committee, is dedicated to increasing awareness of the status of women in Astronomy and supporting the aspirations of female astronomers globally. Its mission includes taking concrete actions to advance equal opportunities for both women and men in the field of astronomy. In August 2021, the IAU WiA Working Group established a new organizing committee, unveiling a comprehensive four-point plan. This plan aims to strengthen various aspects of the group's mission, encompassing: (i) Awareness Sustainability: Achieved through surveys and data collection, (ii) Training and Skill Building: Focused on professional development, (iii) Fundraising: To support key initiatives, and (iv) Communication: Dissemination of results through conferences, WG Magazines, newsletters, and more. This publication provides an overview of focused surveys that illuminate the factors influencing the careers of women in Astronomy, with a particular focus on the careers of mothers. It highlights the lack of inclusive policies, equal opportunities, and funding support for women researchers in the field. Finally, we summarize the specific initiatives undertaken by the IAU WiA Working Group to advance inclusivity and equal opportunities in Astronomy.Comment: 5 pages, 2 figure

Free polar motion of a triaxial and elastic body in Hamiltonian formalism: Application to the Earth and Mars

The purpose of this paper is to show how to solve in Hamiltonian formalism the equations of the polar motion of any arbitrarily shaped elastic celestial body, i.e. the motion of its rotation axis ( or angular momentum) with respect to its figure axis. With this aim, we deduce from canonical equations related to the rotational Hamiltonian of the body, the analytical solution for its free polar motion which depends both on the elasticity and on its moments of inertia. In particular, we study the influence of the phase angle delta, responsible for the dissipation, on the damping of the polar motion. In order to validate our analytical equations, we show that, to first order, they are in complete agreement with those obtained from the classical Liouville equations. Then we adapt our calculations to the real data obtained from the polar motion of the Earth (polhody). For that purpose, we characterize precisely the differences in radius J - chi and in angle l - theta between the polar coordinates (chi, theta) and ( J, l) representing respectively the motion of the axis of rotation of the Earth and the motion of its angular momentum axis, with respect to an Earth-fixed reference frame, after showing the influence of the choice of the origin on these coordinates, and on the determination of the Chandler period as well. Then we show that the phase lag delta responsible for the damping for the selected time interval, between Feb. 1982 and Apr. 1990, might be of the order of delta approximate to 6degrees, according to a numerical integration starting from our analytical equations. Moreover, we emphasize the presence in our calculations for both. and., of an oscillation with a period T(Chandler)/2, due to the triaxial shape of our planet, and generally not taken into account. In a last step, we apply our analytical formulation to the polar motion of Mars, thus showing the high dependence of its damping on the poorly known value of its Love number k. Moreover we emphasize the large oscillations of Mars' polar motion due to the triaxiality of this planet