Geomagnetic Semiannual Variation Is Not Overestimated and Is Not an Artifact of Systematic Solar Hemispheric Asymmetry

Mursula et al. [2011] (MTL11) suggest that there is a 22-year variation in solar wind activity that coupled with the variation in heliographic latitude of the Earth during the year, gives rise to an apparent semiannual variation of geomagnetic activity in averages obtained over several solar cycles. They conclude that the observed semiannual variation is seriously overestimated and is largely an artifact of this inferred 22-year variation. We show: (1) that there is no systematically alternating annual variation of geomagnetic activity or of the solar driver, changing with the polarity of the solar polar fields, (2) that the universal time variation of geomagnetic activity at all times have the characteristic imprint of the equinoctial hypothesis rather than that of the axial hypothesis required by the suggestion of MTL11, and (3) that the semiannual variation is not an artifact, is not overestimated, and does not need revision.Comment: Submitted to GR

A framework for the comparison of different EEG acquisition solutions

The purpose of this work is to propose a framework for the benchmarking of EEG amplifiers, headsets, and electrodes providing objective recommendation for a given application. The framework covers: data collection paradigm, data analysis, and statistical framework. To illustrate, data was collected from 12 different devices totaling up to 6 subjects per device. Two data acquisition protocols were implemented: a resting-state protocol eyes-open (EO) and eyes-closed (EC), and an Auditory Evoked Potential (AEP) protocol. Signal-to-noise ratio (SNR) on alpha band (EO/EC) and Event Related Potential (ERP) were extracted as objective quantification of physiologically meaningful information. Then, visual representation, univariate statistical analysis, and multivariate model were performed to increase results interpretability. Objective criteria show that the spectral SNR in alpha does not provide much discrimination between systems, suggesting that the acquisition quality might not be of primary importance for spectral and specifically alpha-based applications. On the contrary, AEP SNR proved much more variable stressing the importance of the acquisition setting for ERP experiments. The multivariate analysis identified some individuals and some systems as independent statistically significant contributors to the SNR. It highlights the importance of inter-individual differences in neurophysiological experiments (sample size) and suggests some device might objectively be superior to others when it comes to ERP recordings. However, the illustration of the proposed benchmarking framework suffers from severe limitations including small sample size and sound card jitter in the auditory stimulations. While these limitations hinders a definite ranking of the evaluated hardware, we believe the proposed benchmarking framework to be a modest yet valuable contribution to the field

Dodatek k članku »Dinamika podzemne vode med Planinskim poljem in izviri Ljubljanice, Slovenija” objavljenem v Acta Carsologica 48/2

The article of Blatnik et al. (2019) “Groundwater dynamics between Planinsko Polje and springs of the Ljubljanica River, Slovenia” published in Acta Carsologica, 48/2 focused on describing the hydrogeological behaviour of the aquifer between Planinsko Polje and the springs of the Ljubljanica River. The authors analysed the effect of different high water events that occurred between January 2015 and May 2018. Interpretations were based on hydrographs obtained by continuous measurements of water level, temperature and specific electric conductivity in selected ponors, springs and water active caves located in the area between Planinsko Polje and the springs of the Ljubljanica River. Through these interpretations, different conceptual hydrological models about the dynamics and directions of the flow in the aquifer have been proposed and tested. A flow connection was proposed between the Hrušica Plateau, estavelles located at the NW border of Planinsko Polje, and caves Gradišnica (W2) and Gašpinova Jama (W3) close to town Logatec. In this supplement, we provide new data recorded during an unusual hydrological event in August 2018. These further support and stress the importance of the connection between the Hrušica Plateau and Logatec region (W2 and W3).Članek »Dinamika podzemne vode med Planinskim poljem in izviri Ljubljanice, Slovenija«, ki je bil objavljen v Acta Carsologica 48/2, se je v osnovi osredotočil na raziskave pretakanja podzemne vode med Planinskim poljem in izviri Ljubljanice. Med rezultati so bila izpostavljena tudi nova dognanja o smereh pretakanja podzemne vode, ki so bila ugotovljena na podlagi zveznih meritev vodostajev, temperature in specifične električne prevodnosti vode ter testiranja z numeričnimi hidravličnimi modeli. Med drugim je bila ugotovljena domnevna smer pretakanja vode iz jam Veliko brezno v Grudnovi dolini (H1) in Andrejevega brezna 1 (H2), ki se nahajata na vzhodnem pobočju planote Hrušica. Od tu naj bi se voda v času visokih vodostajev pretakala v več smeri, in sicer proti estavelam pri Grčarevcu (SZ rob Planinskega polja) ter proti območju Logaškega ravnika, kjer se nahajata jami Gradišnica (W2) in Gašpinova jama (W3). Pričujoč dodatek k članku potrjuje pretekle domneve, v njej pa opisujemo manj običajen padavinski dogodek iz konca avgusta 2018, ko je na območju Hrušice padla mnogo večja količina padavin kot v preostalem delu porečja Ljubljanice. Rezultat je bil rahlo povišan pretok Unice, pri katerem je voda dosegla le vzhodno skupino požiralnikov na Planinskem polju. Posledično so se vodostaji v nekaterih dolvodno ležečih jamah Vetrovna jama pri Laški kukavi (E2) in Najdena jama (W1) zelo malo povišali (< 2 m). Mnogo bolj izrazit in zelo hiter je bil dvig vodostaja v jamah na pobočju Hrušice (do 37 m v H1). Porast vodostaja v jamah Gradišnica (W2) in Gašpinova jama (W3) je bil znaten (14 m), prav tako je do odziva in viška prišlo le malo po porastu v Velikem breznu v Grudnovi dolini (H1). Ob teh predpostavkah in dejstvu, da je bil dotok iz Planinskega polja zelo skromen, je hidrološka povezava med planoto Hrušico na eni strani Idrijske prelomne cone in območjem z Gradišnico (W2) in Gašpinovo jamo (W3) na drugi strani nedvoumna. Meritve s tem podkrepijo tudi domneve, da se na proučevanem območju nahajajo zožitve in različno prevodna območja Idrijske prelomne cone, ki vplivajo na zelo sinhrono dinamiko vodostajev. Proučevan padavinski dogodek je nakazal tudi, da je dotok iz območja Hrušice lahko zelo izdaten, saj se je najvišji pretok Ljubljanice (~71 m3/s) izrazito presegel tistega na Unici (11 m3/s). Pričujoč dodatek k članku torej potrjuje domneve v predhodno opisanem članku, hkrati pa tudi poudarja pomen dolgoročnih meritev v kraških vodonosnikih, ki v množici medsebojno podobnih zabeležijo tudi nekatere manj običajne, a za interpretacije zelo pomembne dogodke

Groundwater dynamics between Planinsko Polje and springs of the Ljubljanica River, Slovenia

Caves reaching the (epi)phreatic zone may provide the only access to groundwater in the internal parts of karst aquifers. Modern instruments enable unattended high frequency measurements of groundwater parameters in such caves. A network of distributed observation points may give new information on temporal and spatial pattern of groundwater flow. Such network, recording water level, temperature and specific electrical conductivity was established in all major ponors and active water caves of the karst aquifer between Planinsko Polje and springs of the Ljubljanica River, Slovenia. Up to three and a half years long records were analysed in view of available and relevant geological, speleological, meteorological and hydrological information, and basic hydraulic principles of the epiphreatic flow. The result of the interpretation were models of possible conduit networks of the three main flow subsystems draining Planinsko Polje. For each subsystem a hydraulic model comprising the main features of the inferred conduit network and inputs was made. The models were adjusted until their response to the typical flood situations gave a good qualitative fit to the response of the observation network. The results provide new insights into the mechanism of flood propagation through the system and its relation to the known conduit geometry. The hydraulic role of known cave passages is assessed and new flow pathways are proposed. Back-flooding within the aquifer causes an increase of head in the polje, followed by the activation of higher located ponor zones and flow pathways related to them. Hydrographs recorded in two caves located northwest from Planinsko Polje revealed pos sible high transmissivity zone of the Idrija Fault Zone and the mechanism of estavelles located at the polje’s north-western border. The approach taken in this work offers new insights into the relation between the conduit network geometry and flood mechanism. It can be used elsewhere in conduit-dominated systems with multiple accesses to groundwater flow and well constrained recharge.Key words: karst aquifer, epiphreatic zone, groundwater monitoring, hydraulic models, Planinsko Polje, Ljubljanica River.Dinamika podzemne vode med Planinskim poljem in izviri Ljubljanice, Slovenija Jame v epifratični coni običajno predstavljajo edini dostop do podzemne vode znotraj kraškega vodonosnika. Sodobni merilniki omogočajo kakovostne zvezne meritve različnih parametrov tudi v takšnih jamah. Merilna mreža z več lokacijami znotraj izbranega vodonosnika lahko ponudi nove podatke o časovni in prostorski dinamiki toka podzemne vode. Takšna merilna mreža, z meritvami višine, temperature in elektroprevodnosti vode, je bila vzpostavljena v vseh pomembnejših ponorih in vodnih jamah na območju med Planinskim poljem in izviri Ljubljanice. Do tri in pol leta dolgi nizi podatkov so bili analizirani z vidika razpoložljivih geoloških, speleoloških, meteoroloških in hidroloških podatkov ter osnovnih hidravličnih načel o epifreatičnem toku vode. Rezultat interpretacij so poenostavljeni modeli z domnevno razporeditvijo podzemnih kanalov v treh glavnih podsistemih, ki odvajajo Planisko polje. Za vsak podsistem je bil napravljen hidravličen model z dotokom in mrežo kanalov, ki najbolje ponazarja resnično stanje. Tekom raziskave so se hidravlični modeli nadgrajevali do takšne mere, da je simulacija vodnega toka zadovoljivo ponazarjala dogajanje, izmerjeno v resničnem okolju. Rezultati so prinesli nove ugotovitve o širjenju in dinamiki poplavljanja skozi sistem ter njihovo povezavo s poznano geometrijo proučevanega vodonosnika. Ocenjena je bila hidravlična vloga poznanih jamskih rovov, na podlagi njih pa interpretirane nove smeri pretakanja vode. Ugotovljeno je bilo tudi zajezitveno poplavljanje znotraj vodonosnika, ki vpliva tudi na vodostaj na polju in nadalje na aktivacijo višje ležečih požiralnikov ter njim sledečih kanalov. V dveh jamah severozahodno od Planinskega polja so višinski hidrogrami nakazali na obstoj bolj prepustnega območja Idrijske prelomne cone ter delovanje estavel na severozahodnem obrobju polja. Postopek, ki je bil uporabljen v pričujočem delu, omogoča nova dognanja o razporeditvi podzemnih kanalov in s tem povezano dinamiko poplavljanja v kraškem vodonosniku. Predstavljeno metodo je mogoče uporabiti tudi v drugih kraških sistemih z dobro razvitimi kanali, z več dostopi do toka podzemne toka vode in dobro poznanem dotoku v sistem.Ključne besede: kraški vodonosnik, epifreatična cona, spremljanje podzemne vode, hidravlični modeli, Planinsko polje, Ljubljanica

'It's not about money, it's about my health': determinants of participation and adherence among women in an HIV-HSV2 prevention trial in Johannesburg, South Africa.

High levels of adherence in clinical trials are essential for producing accurate intervention efficacy estimates. Adherence to clinical trial products and procedures is dependent on the motivations that drive participants. Data are presented to document reasons for trial participation and adherence to daily aciclovir for HSV-2 and HIV-1 genital shedding suppression among 300 HIV-1/HSV-2 seropositive women in South Africa. In-depth interviews after exit from the trial with 31 randomly selected women stratified by age and time since HIV diagnosis confirmed high levels of adherence measured during the trial. Main reasons for trial participation were related to seeking high-quality health care, which explains high levels of adherence in both study arms. Concerns that women would abuse reimbursements, fabricate data, and share or dump pills were not corroborated. Altruism is not a primary motivator in these settings where access to quality services is an issue. This study provides further evidence that good adherence of daily medication is possible in developing countries, particularly where study activities resonate with participants or fill an unmet need