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Assuming that the Universe at higher redshifts ($z \sim 4$ and beyond) is consistent with \lcdm model as constrained by the Planck measurements, we reanalyze the low redshift cosmological data to reconstruct the Hubble parameter as a function of redshift. This enables us to address the $H_0$ and other tensions between low $z$ observations and high $z$ Planck measurement from CMB. From the reconstructed $H(z)$, we compute the energy density for the ``dark energy'' sector of the Universe as a function of redshift {without assuming a specific model for dark energy}. We find that the dark energy density has a minimum for certain redshift range and that the value of dark energy at this minimum $\rde^{\text{min}}$ is negative. This behavior can most simply be described by a {negative cosmological constant} plus an evolving dark energy component. We discuss possible theoretical and observational implications of such a scenario.
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