Clearly, previous literatures either focus on heuristic algorithms, which remain difficult to characterize and have no performance guarantee [4 7, 18], or employ a strict constraint to reduce complexity [8, 9], which cannot be extended to accommodate the general case.
They have "increased oligopoly power" and "remain difficult to control because they have the lawyers and the money to resist the pressures of federal regulation," Harvey Rosenblum, the head of the Dallas Fed's research department, wrote in the essay.
Although the creativity and serendipity of individual discoveries will remain difficult to model, quantitative research has revealed regularities in the rates of discovery and the outcome of published findings over time (1).
Without a nationally consistent approach to data development relating to perinatal mental health, it will remain difficult to ascertain if these key initiatives have had the desired effect of increasing rates of depression screening and psychosocial assessment among perinatal populations in service areas where implementation has occurred.
While SSRs remain difficult to develop, SNP identification and validation has rapidly improved in past years mostly due to reduction of sequencing costs.
Radiographic imaging is limited by the thickness of the surrounding soft tissues [11]; ultrasonic, scintigraphic approaches all have an interest but remain difficult to apply in field conditions and on a large sample of horses [16], [11].
As donated organs have remained difficult to procure, transplant operations have become safer and easier.
Some divides have remained difficult to bridge and new divides have emerged.
This remained difficult to judge, and there had been few developments to shed light on it since the Committee's previous meeting.
Additionally, strategies have been described in the literature [20], [21], unfortunately, these have remained difficult to reproduce.
