Krzysztof Czajkowski

Prof. Dr. Krzysztof Czajkowski


Research Focus & Metrics

Academic Career Length

43Years (1984-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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18 April 2016 in Journal of Endocrinological Investigation
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Journal Article
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APA. Podfigurna-Stopa
A. Podfigurna-Stopa
ACA. Czyzyk
A. Czyzyk
MGMonika Grymowicz
Monika Grymowicz
RSR. Smolarczyk
R. Smolarczyk
KKK. Katulski
K. Katulski
Blazej MeczekalskiBlazej Meczekalski
Blazej Meczekalski
Purpose Premature ovarian insufficiency (POI) is defined as the cessation of the ovarian function before the age of 40 years. POI aetiology may be related to iatrogenic or endogenous factors and in many cases remains unclear. The aim of this review was to characterize the long-term consequences of POI. Methods The available literature regarding the long-term consequences of POI from MEDLINE has been reviewed. Results Lack of ovarian steroids synthesis has serious consequences for women’s health. The short-term effects are similar to spontaneous menopause and refer mainly to the climacteric syndrome. In a longer perspective, POI affects a variety of aspects. It obviously and drastically reduces the chances for spontaneous pregnancies. Oestrogen loss leads also to urogenital atrophy. The most common urogenital symptoms include vaginal dryness, vaginal irritation and itching. The urogenital atrophy and hypoestrogenism interferes also with sexual functioning. Patients with POI are threatened by a decrease in bone mineral density (BMD). POI women also experience psychological distress and some studies have shown an increased risk of neurodegenerating diseases. Overall, POI women have a shortened life expectancy, mainly due to cardiovascular disease. Some studies have reported a reduced risk of breast cancer in this group of patients. Conclusions In conclusion there are several well-characterized health risks in POI women. With every patient, an individualized approach is required to properly recognize and prevent these risks.

25 July 2018 in Optics Express
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KCKrzysztof Czajkowski
Krzysztof Czajkowski
APAnna Pastuszczak
Anna Pastuszczak
RKRafał Kotyński
Rafał Kotyński
We present a closed-form image reconstruction method for single-pixel imaging based on the generalized inverse of the measurement matrix. Its numerical cost scales proportionally with the number of measured samples. Regularization of the inverse problem is obtained by minimizing the norms of the convolution between the reconstructed image and a set of spatial filters. The final reconstruction formula can be expressed in terms of matrix pseudoinverse. At high compression, this approach is an interesting alternative to the methods of compressive sensing based on l1-norm optimization, which are too slow for real-time applications. For instance, we demonstrate experimental single-pixel detection with real-time reconstruction obtained in parallel with measurement at a frame rate of 11 Hz for highly compressive measurements with a resolution of 256 × 256. To this end, we preselect the sampling functions to match the average spectrum obtained with an image database. The sampling functions are selected from the Walsh-Hadamard basis, from the discrete cosine basis, or from a subset of Morlet wavelets convolved with white noise. We show that by incorporating the quadratic criterion into the closed-form reconstruction formula, we can use binary rather than continuous sampling and reach similar reconstruction quality as is obtained by minimizing the total variation. This makes it possible to use cosine- or Morlet-based sampling with digital micromirror devices without advanced binarization methods.

28 February 2005 in Proceedings of the IEEE
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IFI. Foster
I. Foster
KCKrzysztof Czajkowski
Krzysztof Czajkowski
DFD.E. Ferguson
D.E. Ferguson
JFJ. Frey
J. Frey
SGS. Graham
S. Graham
STS. Tuecke
S. Tuecke
We often encounter in distributed systems the need to model, access, and manage state. This state may be, for example, data in a purchase order, service level agreements representing resource availability, or the current load on a computer. We introduce two closely related approaches to modeling and manipulating state within a Web services (WS) framework: the Open Grid Services Infrastructure (OGSI) and WS-Resource Framework (WSRF). Both approaches define conventions on the use of the Web service definition language schema that enable the modeling and management of state. OGSI introduces the idea of a stateful Web service and defines approaches for creating, naming, and managing the lifetime of instances of services; for declaring and inspecting service state data; for asynchronous notification of service state change; for representing and managing collections of service instances; and for common handling of service invocation faults. WSRF refactors and evolves OGSI to exploit new Web services standards, specifically WS-addressing, and to respond to early implementation and application experiences. WSRF retains essentially all of the functional capabilities present in OGSI, while changing some syntax (e.g., to exploit WS-addressing) and also adopting a different terminology in its presentation. In addition, WSRF partitions OGSI functionality into five distinct composable specifications. We explain the relationship between OGSI and WSRF and the related WS-notification specifications, explain the common requirements that both address, and compare and contrast the approaches taken to the realization of those requirements.

20 July 2015 in Journal of Geophysical Research: Biogeosciences
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CSChangliang Shao
Changliang Shao
Jiquan ChenJiquan Chen
Jiquan Chen
CSCarol A. Stepien
Carol A. Stepien
HCHousen Chu
Housen Chu
ZYZutao Yang
Zutao Yang
RJRanjeet John
Ranjeet John
To understand the carbon and energy exchange between the lake surface and the atmosphere, direct measurements of latent, sensible heat, and CO2 fluxes were taken using the eddy covariance (EC) technique in Western Lake Erie during October 2011 to September 2013. We found that the latent heat flux (LE) had a marked one‐peak seasonal change in both years that differed from the diurnal course and lacked a sinusoidal dynamic common in terrestrial ecosystems. Daily mean LE was 4.8 ± 0.1 and 4.3 ± 0.2 MJ m−2 d−1 in Year 1 and Year 2, respectively. The sensible heat flux (H) remained much lower than the LE, with a daily mean of 0.9 ± 0.1 and 1.1 ± 0.1 MJ m−2 d−1 in Year 1 and Year 2, respectively. As a result, the Bowen ratio was <1 during most of the 2 year period, with the lowest summer value at 0.14. The vapor pressure deficit explained 35% of the variation in half hourly LE, while the temperature difference between the water surface and air explained 65% of the variation in half hourly H. Western Lake Erie acted as a small carbon sink holding −19.0 ± 5.4 and −40.2 ± 13.3 g C m−2 in the first and second summers (May–September) but as an annual source of 77.7 ± 18.6 and 49.5 ± 17.9 g C m−2 yr−1 in Year 1 and Year 2, respectively. The CO2 flux ( ) rate varied from −0.45 g C m−2 d−1 to 0.98 g C m−2 d−1. Similar to LE, had noticeable diurnal changes during the months that had high chlorophyll a months but not during other months. A significantly negative correlation (P < 0.05) was found between and chlorophyll a on monthly fluxes. Three gap‐filling methods, including marginal distribution sampling, mean diurnal variation, and monthly mean, were quantitatively assessed, yielding an uncertainty of 4%, 6%, and 10% in LE, H, and , respectively.

1 December 2001 in Diabetes Technology & Therapeutics
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JWJ. M. Wojcicki
J. M. Wojcicki
Piotr LadyzynskiPiotr Ladyzynski
Piotr Ladyzynski
JKJ. Krzymien
J. Krzymien
EJE. Jozwicka
E. Jozwicka
JBJ. Blachowicz
J. Blachowicz
WKW. Karnafel
W. Karnafel
Existing standards of the management of the diabetic patients are not efficient enough, and further improvement is needed. The major objective of this paper is to present and discuss the therapeutic effectiveness of an intensive care telematic system designed and applied for intensive treatment of pregnant type 1 diabetic women. The developed system operates automatically, every night transferring all the data recorded during the day in the patient's glucometer memory to a central clinical unit. In order to assess the efficiency of the designed and developed system, a 3-year randomized prospective clinical trial was conducted, using the study group and the control group, each consisting of 15 pregnant type 1 diabetic women. All patients were treated by the same diabetologist. In the presented analysis, two indices calculated weekly were used for the assessment of glycemic control: MBG represents mean blood glucose level, and the universal J-index is sensitive to the glycemic level and glycemic variations. The most important results from the study concern: (a) better glycemic control in the study group in comparison with the control group during the course of treatment, as assessed by the average differences of the MBG and J indices calculated weekly (n = 24) (ΔMBG = -3.2 ± 4.3 mg/dL, p = 0.0016, ΔJ = -1.4 ± 2.3, p = 0.0065); (b) much more similar results in glycemic control among members of the study group compared to each other, than among members of the control group compared to each other, as indicated by significantly lower variations of the applied glycemic control indices (SDMBG: 11.9 vs. 18.7 mg/dL, p = 0.0498; SDJ: 6.5 vs. 10.9, p = 0.0318); (c) the observed tendency of a better glycemic control for patients with a lower level of intelligence (IQ < 100) supported by the telematic system in comparison with all other assessed groups of patients. The last result was not statistically significant (p > 0.05). This telematic intensive care system improved the effectiveness of diabetes treatment during pregnancy. It also allows the diabetologist's strategy to be much more precise than if it were conducted without telematic support. This telematic system is inexpensive and simple in use.

7 October 2014 in Global Change Biology
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HCHousen Chu
Housen Chu
JGJohan F. Gottgens
Johan F. Gottgens
Jiquan ChenJiquan Chen
Jiquan Chen
Ge SunGe Sun
Ge Sun
ADAnkur Desai
Ankur Desai
KCKrzysztof Czajkowski
Krzysztof Czajkowski