Twenty-three unsolved problems in hydrology (UPH) – a community perspective

This paper is the outcome of a community initiative to identify major unsolved scientific problems in hydrology motivated by a need for stronger harmonisation of research efforts. The procedure involved a public consultation through on-line media, followed by two workshops through which a large number of potential science questions were collated, prioritised, and synthesised. In spite of the diversity of the participants (230 scientists in total), the process revealed much about community priorities and the state of our science: a preference for continuity in research questions rather than radical departures or redirections from past and current work. Questions remain focussed on process-based understanding of hydrological variability and causality at all space and time scales. Increased attention to environmental change drives a new emphasis on understanding how change propagates across interfaces within the hydrological system and across disciplinary boundaries. In particular, the expansion of the human footprint raises a new set of questions related to human interactions with nature and water cycle feedbacks in the context of complex water management problems. We hope that this reflection and synthesis of the 23 unsolved problems in hydrology will help guide research efforts for some years to come

Social media conflicts during the financial crisis: Managerial implications for retail banks

Social media can be used proactively to disseminate accurate corporate information and address undesirable consumer behaviors online in order to help counteract negativity in the business environment in the wake of a financial crisis. Social media thus has become a popular open forum for financial institutions such as retail banks to engage in corporate dialogue with consumers. We recommend that financial services firms preemptively use their social media?based online communities in order to disseminate accurate corporate information in times of a financial crisis. Particularly, firms can choose between a range of reactive and proactive strategies to manage social conflict in the wake of a financial crisis

Comparison of microperc and mini-percutaneous nephrolithotomy for medium-sized lower calyx stones

The objective of this study was to present the outcomes of comparative clinical study of microperc versus mini-percutaneous nephrolithotomy (mini-PNL) in the treatment of lower calyx stones of 10–20 mm. Patients with lower calyx stones treated with microperc (Group-1) or mini-PNL (Group-2) between 2011 and 2014 were retrospectively analyzed. Demographics of the patients were compared, including age, gender, BMI, stone size, laterality and procedural parameters (operation and fluoroscopy time), and outcomes (success and complication rates). A total of 98 patients were evaluated, assigned to Group-1 (n = 58) and to Group-2 (n = 40). Groups were statistically similar in terms of age, stone size, and BMI (p = 0.3, 0.07, 0.6, respectively). The mean procedure and fluoroscopy duration for Group-1 were 43.02 ± 27.98 min and 112.05 ± 72.5 s, and 52.25 ± 23.09 min and 138.53 ± 56.39 s in Group-2 (p = 0.006 and 0.006). The mean hematocrit drop was significantly higher in Group-2 compared to Group-1 (3.98 vs. 1.96 %; p < 0.001); however, none of the cases required blood transfusion. Overall complication rates exhibited no statistically significant difference (p = 0.57). Stone-free status was similar (86.2 vs. 82.5 %, p = 0.66). The tubeless procedure rate was significantly higher in Group-1 (p < 0.001). In Group-2, duration of hospitalization was significantly longer than in Group-1 (2.63 vs. 1.55 days; p < 0.01). Outcomes of the present retrospective study show that microperc is a treatment option for medium-sized lower calyx stone, being associated with lower blood loss, procedure, reduced fluoroscopy and hospitalization time, and a higher tubeless rate. © 2015, Springer-Verlag Berlin Heidelberg

Efficient benzodithiophene and thienopyrroledione containing random polymers as components for organic solar cells

Benzodithiophene and thienopyrroledione containing two random copolymers were designed and synthesized. Electrochemical and optical studies prove that these copolymers could be candidates for organic solar cells applications. The HOMO and LUMO values were determined using cyclic voltammetry as -5.53 and -3.43 eV for P1 and -5.54 and -3.53 eV for P2, respectively. The optical band gaps of the polymers were calculated as 2.10 and 2.01 eV using UV-VIS spectroscopy for P1 and P2, correspondingly. Bulk-heterojunction solar cells were constructed with the configuration of ITO/PEDOT:PSS/Polymer:PC71BM/LiF/Al and the synthesized polymers were used as the electron donors and PC71BM as the electron acceptor in the active layer. The best performance was observed for device of P2 1:2 (w:w) ratio with a V-oc 0.80 V, a J(sc) of 14.02 mA/cm(2), a fill factor of 52%, and a PCE of 5.83% under standard AM 1.5 G at 100 mW/cm(2)

Investigation of on-wafer TRL calibration accuracy dependence on transitions and probe positioning

This paper presents the effects of various transition types from the measurement plane to the reference plane in TRL calibration and probe positioning effects for on wafer measurements of CPW based devices. Fourteen different transition types, with direct, linear and exponential transitions, including 3 different variations of ground-signal-ground (GSG) spacing are examined. To observe the performance of the transitions, simple CPW transmission lines of different characteristic impedances are fabricated using standard lithography techniques on glass substrate and S-parameters are measured in 4.5-20 GHz band. Results are compared with electromagnetic simulations. The effects of probe misplacement along the lateral and horizontal axis are also investigated

Synthesis of a benzotriazole bearing alternating copolymer for organic photovoltaic applications

A low band gap donor-acceptor (D-A) copolymer PTBTBDT, namely, poly(2-dodecyl-4,7-di(thiophen-2-yl)-2H-benzo[d][1,2,3]triazole-alt-4,8-bis(2-ethylhexyloxy) benzo[1,2-b:4,5-b'] dithiophene), was designed and synthesized via a Pd-catalyzed Stille polycondensation reaction. The polymer was characterized using H-1 NMR spectroscopy, UV-vis absorption spectroscopy, cyclic voltammetry, and gel permeation chromatography (GPC). PTBTBDT has good solubility in common organic solvents, good thermal stability, broad absorption, low band gap and exhibits not only high hole mobility but also moderate photovoltaic properties. PTBTBDT displays broad absorption in the wavelength range from 300 nm to 630 nm, and its HOMO and LUMO energy levels were calculated to be -4.98 eV and -3.34 eV, respectively. Bulk heterojunction solar cells were fabricated using PTBTBDT as the electron donor and PC70BM as the acceptor. The device exhibits a power conversion efficiency of 2.12% with a current density of 5.45 mA cm(-2), an open-circuit voltage of 0.72 V, and a fill factor of 54% under the illumination of AM 1.5 G, 100 mW cm(-2). Under similar device fabrication conditions, the PTBTBDT based device showed considerably improved efficiency among its previously synthesized counterparts, i.e. PBDTDTBTz and PBDTBTz based devices, which have 1.7% and 1.4% efficiencies, respectively. The hole mobility of the PTBTBDT : PC70BM (1 : 2 w/w) blend reached up to 1.47 x 10(-3) cm(2) V-1 s(-1) as calculated by the space-charge-limited current (SCLC) method. By side-chain engineering, this study demonstrates a good example of tuning the absorption range, energy level, charge transport, and photovoltaic properties of polymers