Search results for " nodal"

Symmetry Breaking and Establishment of Dorsal/Ventral Polarity in the Early Sea Urchin Embryo

2015

The mechanisms imposing the Dorsal/Ventral (DV) polarity of the early sea urchin embryo consist of a combination of inherited maternal information and inductive interactions among blastomeres. Old and recent studies suggest that a key molecular landmark of DV polarization is the expression of nodal on the future ventral side, in apparent contrast with other metazoan embryos, where nodal is expressed dorsally. A subtle maternally-inherited redox anisotropy, plus some maternal factors such as SoxB1, Univin, and p38-MAPK have been identified as inputs driving the spatially asymmetric transcription of nodal. However, all the mentioned factors are broadly distributed in the embryo as early as no…

A nonlinear eigenvalue problem for the periodic scalar p-Laplacian

2014

We study a parametric nonlinear periodic problem driven by the scalar $p$-Laplacian. We show that if $\hat \lambda_1 >0$ is the first eigenvalue of the periodic scalar $p$-Laplacian and $\lambda> \hat \lambda_1$, then the problem has at least three nontrivial solutions one positive, one negative and the third nodal. Our approach is variational together with suitable truncation, perturbation and comparison techniques.

Three solutions for parametric problems with nonhomogeneous (a,2)-type differential operators and reaction terms sublinear at zero

2019

Abstract We consider parametric Dirichlet problems driven by the sum of a Laplacian and a nonhomogeneous differential operator ( ( a , 2 ) -type equation) and with a reaction term which exhibits arbitrary polynomial growth and a nonlinear dependence on the parameter. We prove the existence of three distinct nontrivial smooth solutions for small values of the parameter, providing sign information for them: one is positive, one is negative and the third one is nodal.

Multiple solutions for nonlinear nonhomogeneous resonant coercive problems

2018

We consider a nonlinear, nonhomogeneous Dirichlet problem driven by the sum of a \begin{document}$p$\end{document} -Laplacian ( \begin{document}$2 ) and a Laplacian. The reaction term is a Caratheodory function \begin{document}$f(z,x)$\end{document} which is resonant with respect to the principal eigenvalue of ( \begin{document}$-\Delta_p,\, W^{1,p}_0(\Omega)$\end{document} ). Using variational methods combined with truncation and comparison techniques and Morse theory (critical groups) we prove the existence of three nontrivial smooth solutions all with sign information and under three different conditions concerning the behavior of \begin{document}$f(z,\cdot)$\end{document} near zero. By …

A multiplicity theorem for parametric superlinear (p,q)-equations

2020

We consider a parametric nonlinear Robin problem driven by the sum of a \(p\)-Laplacian and of a \(q\)-Laplacian (\((p,q)\)-equation). The reaction term is \((p-1)\)-superlinear but need not satisfy the Ambrosetti-Rabinowitz condition. Using variational tools, together with truncation and comparison techniques and critical groups, we show that for all small values of the parameter, the problem has at least five nontrivial smooth solutions, all with sign information.

Suppression of nodal expression in prospective dorsal cells of the early sea urchin embryo by the hbox12 homeodomain regulator

2014

Dorsal/Ventral (DV) axis formation in the sea urchin embryo depends upon the expression of nodal on the ventral side, which behaves as a DV organizing centre. However, only fuzzy clues are known as to the early symmetry-breaking steps that lead to the positioning of such an organizer. An extremely interesting candidate for this role is the hbox12 homeobox-containing gene. In Paracentrotus lividus, hbox12 expression is antecedent and complementary with respect to that of nodal, being confined in prospective dorsal cells. We show that ectopic expression of Hbox12 provokes DV abnormalities and attenuates nodal as well as nodal-dependent gene transcription. By blastomere transplantation, we als…

Multiple solutions with sign information for a (p,2)-equation with combined nonlinearities

2020

We consider a parametric nonlinear Dirichlet problem driven by the sum of a p-Laplacian and of a Laplacian (a (p,2)-equation) and with a reaction which has the competing effects of two distinct nonlinearities. A parametric term which is (p−1)-superlinear (convex term) and a perturbation which is (p−1)-sublinear (concave term). First we show that for all small values of the parameter the problem has at least five nontrivial smooth solutions, all with sign information. Then by strengthening the regularity of the two nonlinearities we produce two more nodal solutions, for a total of seven nontrivial smooth solutions all with sign informations. Our proofs use critical point theory, critical gro…

A rare case report of variable degrees of atrioventricular block during atrioventricular nodal reentrant tachycardia

2020

Medikamentu administrēšana vispārējās aprūpes nodaļā

2021

Bakalaura darba tēma – „Medikamentu administrēšana vispārējās aprūpes nodaļā” aktualitāte pamatota ar to, ka mūsdienās arvien vairāk parādās kļūdas medikamentu administrēšanā. Bakalaura darba mērķis ir noskaidrot kāda ir medikamentu administrēšana vispārējas aprūpes nodaļās. Darbā ir izvēlēta kvantitatīvā pētniecības metode – anketa. Darba hipotēze ir apstiprinājusies daļēji, jo pastāv kļūdu iespēja pareizā medikamentu administrēšanā vispārējās aprūpes nodaļā, kas var ietekmēt pacientu atveseļošanos. Atslēgas vārdi: medikamenti, administrēšana, vispārējās aprūpes nodaļa.

Saukas ezera fitoplanktona raksturojums

2022

Bakalaura darbs tika veikts saskaņā ar projekta “Latvijas upju baseinu apsaimniekošanas plānu ieviešana laba virszemes ūdens stāvokļa sasniegšanai” (LIFE GoodWater IP, 23 Nr. LIFE18IPE/LV/000014) ietvaros. Pētījuma mērķis bija izvērtēt Saukas ezera ekoloģisko stāvokli 2020. un 2021. gada vasarā pēc fitoplanktona kvantitatīvajiem un kvalitatīvajiem rādītājiem. 2020. gada fitoplanktona paraugos Saukas ezerā tika konstatētās 84 fitoplanktona sugas no septiņiem aļģu nodalījumiem. Jūlijā konstatētas augstākās fitoplanktona biomasas pateicoties kramaļģēm un zilaļģēm. 2021. gadā tika konstatētas 63 fitoplanktona sugas no astoņiem fitoplanktona nodalījumiem. Apsekotajās paraugošanas stacijās dominē…