Mehmet Emin Demirkol profile image
Mehmet Emin Demirkol Assoc. Prof. Dr. ÇUKUROVA ÜNİVERSİTESİ
Publication 33 Review 260 CrossRef Cited 63 TR Dizin Cited 76
33 Publication
260 Review
63 CrossRef Cited
76 TR Dizin Cited
0000-0003-3965-7360

Research Fields

Psychiatry Subtance Abuse

Institution

ÇUKUROVA ÜNİVERSİTESİ

Popular Publications

Attention Deficit Hyperactivity Disorder in the Elderly
Authors: Çağatay Çavuşoğlu, Mehmet Emin Demirkol , Lut Tamam
Published: 2020 , Current Approaches in Psychiatry
DOI: 10.18863/pgy.548052
CITED 1 FAVORITE 2 TOTAL DOWNLOAD COUNT 6161

1

2

6161

Assessment of suicidal behavior in bipolar disorder
Authors: Kerim Uğur, Lut Tamam , Nurgül Özpoyraz, Mehmet Emin Demirkol
Published: 2019 , Cukurova Medical Journal
DOI: 10.17826/cumj.503328
CITED 1 FAVORITE 1 TOTAL DOWNLOAD COUNT 2310

1

1

2310

Relationship between compulsive buying disorder and attention deficit hyperactivity disorder
Authors: Meliha Zengin Eroğlu , Mehmet Emin Demirkol , Lut Tamam , Volkan Gelegen
Published: 2019 , Cukurova Medical Journal
DOI: 10.17826/cumj.559531
CITED 1 FAVORITE 1 TOTAL DOWNLOAD COUNT 2092

1

1

2092

The relationship between metabolic syndrome and vitamin D levels in patients with schizophrenia
Authors: Mehmet Emin Demirkol , Lut Tamam , Soner Çakmak , Caner Yeşiloğlu
Published: 2019 , Cukurova Medical Journal
DOI: 10.17826/cumj.569373
CITED 4 FAVORITE 1 TOTAL DOWNLOAD COUNT 1989

4

1

1989

Bipolar Bozukluk Tanılı Hastalarda Tedaviye Uyum ve İlişkili Faktörler
Authors: Mahmut Onur Karaytuğ , Lut Tamam , Mehmet Emin Demirkol , Zeynep Namlı
Published: 2022 , Archives Medical Review Journal
DOI: 10.17827/aktd.1055451
CITED 5 FAVORITE 1 TOTAL DOWNLOAD COUNT 2884

5

1

2884

Publications

Alexithymia Across Psychiatric Disorders
Authors: Tunahan Sun , Lut Tamam , Mehmet Emin Demirkol , Caner Yeşiloğlu
Published: 2026 , Current Approaches in Psychiatry
DOI: 10.18863/pgy.1839731
FAVORITE 0 TOTAL DOWNLOAD COUNT 728

0

728

Impact of brief structured psychoeducation on quality of life, medication adherence, and health anxiety in euthymic patients with bipolar disorder
Authors: Caner Yeşiloğlu , Lut Tamam , Mehmet Emin Demirkol , Tugrul Demireğen , Cennet Yaren Sarıoğlu , Ömer Fettahlıoğlu , Damla Altın
Published: 2025 , Cukurova Medical Journal
DOI: 10.17826/cumj.1803773
FAVORITE 0 TOTAL DOWNLOAD COUNT 332

0

332

Relationship of Social Media Use with Psychological Well-Being and Quality of Life in Medical Students
Authors: Mehmet Emin Demirkol , Sinem Çetin Demirtaş , Caner Yeşiloğlu , İrem Sanem Sabahi , Lut Tamam
Published: 2025 , Current Approaches in Psychiatry
DOI: 10.18863/pgy.1680979
FAVORITE 0 TOTAL DOWNLOAD COUNT 899

0

899

The Relationship Between Anxiety Levels and Psychological Resilience of Earthquake Victims and Their Cigarette and Internet Use
Authors: Burcu Dinçer , Mehmet Emin Demirkol , Lut Tamam , Caner Yeşiloğlu
Published: 2025 , Journal of Dependence
DOI: 10.51982/bagimli.1637264
FAVORITE 1 TOTAL DOWNLOAD COUNT 812

1

812

The Psychiatric Dimensions of Impulsivity
Authors: Caner Yeşiloğlu , Tunahan Sun , Mehmet Emin Demirkol , Lut Tamam
Published: 2025 , Archives Medical Review Journal
DOI: 10.17827/aktd.1698682
FAVORITE 1 TOTAL DOWNLOAD COUNT 986

1

986

Impulsivity and Quality of Life in Patients with Substance Use Disorder
Authors: Caner Yeşiloğlu , Lut Tamam , Mehmet Emin Demirkol , Hamdi Yılmaz
Published: 2024 , Journal of Dependence
DOI: 10.51982/bagimli.1466597
FAVORITE 1 TOTAL DOWNLOAD COUNT 2157

1

2157

Misophonia and its Relationship with Other Psychiatric Disorders
Authors: Kemal Mutlu , Lut Tamam , Zeynep Namlı , Mehmet Emin Demirkol , Mahmut Onur Karaytuğ
Published: 2023 , Medical Records
DOI: 10.37990/medr.1208093
FAVORITE 0 TOTAL DOWNLOAD COUNT 3652

0

3652

The Relationship Between Alcohol Use Disorder and Suicide in Patients with Obsessive Compulsive Disorder
Authors: Mahmut Onur Karaytuğ , Lut Tamam , Mehmet Emin Demirkol , Zeynep Namlı
Published: 2023 , Journal of Dependence
DOI: 10.51982/bagimli.1148182
FAVORITE 0 TOTAL DOWNLOAD COUNT 2577

0

2577

Relationship Between Adult Separation Anxiety Disorder and Suicide in Patients with Bipolar Disorder
Authors: Mahmut Onur Karaytuğ , Lut Tamam , Mehmet Emin Demirkol , Zeynep Namlı
Published: 2022 , Current Approaches in Psychiatry
DOI: 10.18863/pgy.1192406
FAVORITE 0 TOTAL DOWNLOAD COUNT 1331

0

1331

Relationship between Online Compulsive Shopping Behavior and Impulsivity in Women
Authors: Zeynep Namlı , Lut Tamam , Mehmet Emin Demirkol , Mahmut Onur Karaytuğ , Aynur Özbay
Published: 2022 , Journal of Dependence
DOI: 10.51982/bagimli.1143636
FAVORITE 0 TOTAL DOWNLOAD COUNT 1988

0

1988

The Relationship of Neurocognitive Impairment and Quality of Life in Patients Diagnosed with Schizophrenia
Authors: Günay Hajıyeva , Soner Çakmak , Lut Tamam , Mahmut Onur Karaytuğ , Mehmet Emin Demirkol , Zeynep Namlı , Said Aktaş
Published: 2022 , Osmangazi Tıp Dergisi
DOI: 10.20515/otd.1097490
FAVORITE 0 TOTAL DOWNLOAD COUNT 1383

0

1383

Bipolar Bozukluk Tanılı Hastalarda Tedaviye Uyum ve İlişkili Faktörler
Authors: Mahmut Onur Karaytuğ , Lut Tamam , Mehmet Emin Demirkol , Zeynep Namlı
Published: 2022 , Archives Medical Review Journal
DOI: 10.17827/aktd.1055451
FAVORITE 1 TOTAL DOWNLOAD COUNT 2884

1

2884

Suicidal Behavior in Individuals with Substance Use Disorder Who Apply to the Probation Outpatient Clinic
Authors: Kerim Uğur , Lut Tamam , Mehmet Emin Demirkol , Sevler Yıldız , Fatma Kartal , Aslı Kazğan , Hatice Polat
Published: 2021 , Journal of Dependence
DOI: 10.51982/bagimli.928360
FAVORITE 0 TOTAL DOWNLOAD COUNT 1429

0

1429

Comparison of antidepressant in terms of drug-related movement disorders and sexual side effects
Authors: Zeynep Namlı , Lut Tamam , Mehmet Emin Demirkol , Mahmut Onur Karaytuğ , Kerim Uğur , Özge Eriş
Published: 2021 , Cukurova Medical Journal
DOI: 10.17826/cumj.865933
FAVORITE 0 TOTAL DOWNLOAD COUNT 9701

0

9701

The relationship of psychoactive substance use with clinical variables in male inpatients with psychotic disorder
Authors: Mahmut Onur Karaytuğ , Lut Tamam , Mehmet Emin Demirkol , Zeynep Namlı , Caner Yeşiloğlu
Published: 2020 , Cukurova Medical Journal
DOI: -
FAVORITE 0 TOTAL DOWNLOAD COUNT 2655

0

2655

Attention Deficit Hyperactivity Disorder in the Elderly
Authors: Çağatay Çavuşoğlu, Mehmet Emin Demirkol , Lut Tamam
Published: 2020 , Current Approaches in Psychiatry
DOI: 10.18863/pgy.548052
FAVORITE 2 TOTAL DOWNLOAD COUNT 6161

2

6161

Anxiety sensitivity in bipolar disorder and schizophrenia
Authors: Zeynep Namlı , Lut Tamam , Mehmet Emin Demirkol , Soner Çakmak
Published: 2020 , Cukurova Medical Journal
DOI: 10.17826/cumj.723876
FAVORITE 0 TOTAL DOWNLOAD COUNT 2573

0

2573

The effect of psychotic symptoms on rehospitalizations at a psychiatric clinic of a university hospital
Authors: Merve Tsakir Chasan , Gonca Karakuş , Lut Tamam , Mehmet Emin Demirkol
Published: 2020 , Mersin Üniversitesi Sağlık Bilimleri Dergisi
DOI: 10.26559/mersinsbd.674605
FAVORITE 0 TOTAL DOWNLOAD COUNT 2118

0

2118

Classification of EEG Signals in Depressed Patients
Authors: Server Göksel Eraldemir , Ümit Kılıç, Mümine Kaya Keleş, Mehmet Emin Demirkol , Esen Yıldırım , Lut Tamam
Published: 2020 , Balkan Journal of Electrical and Computer Engineering
DOI: 10.17694/bajece.631951
FAVORITE 0 TOTAL DOWNLOAD COUNT 1632

0

1632

Attention deficit hyperactivity disorder and impulsivity in patients with trichotillomania
Authors: Meliha Zengin Eroğlu , Ebru Sahan, Mehmet Emin Demirkol , Volkan Gelegen, Lut Tamam
Published: 2019 , Cukurova Medical Journal
DOI: 10.17826/cumj.618470
FAVORITE 0 TOTAL DOWNLOAD COUNT 1936

0

1936

The Relationship Between Antipsychotic Drug Use and Electrocardiography Parameters
Authors: Mehmet Emin Demirkol , Lut Tamam , Soner Çakmak , Caner Yeşiloğlu
Published: 2019 , Current Approaches in Psychiatry
DOI: 10.18863/pgy.598097
FAVORITE 0 TOTAL DOWNLOAD COUNT 5490

0

5490

Relationship between compulsive buying disorder and attention deficit hyperactivity disorder
Authors: Meliha Zengin Eroğlu , Mehmet Emin Demirkol , Lut Tamam , Volkan Gelegen
Published: 2019 , Cukurova Medical Journal
DOI: 10.17826/cumj.559531
FAVORITE 1 TOTAL DOWNLOAD COUNT 2092

1

2092

Acute angle closure glaucoma induced by selective serotonin reuptake inhibitor, and reversed by agomelatine
Authors: Mahmut Onur Karaytuğ , Mehmet Emin Demirkol , Lut Tamam
Published: 2019 , Cukurova Medical Journal
DOI: 10.17826/cumj.572186
FAVORITE 0 TOTAL DOWNLOAD COUNT 2087

0

2087

The relationship between metabolic syndrome and vitamin D levels in patients with schizophrenia
Authors: Mehmet Emin Demirkol , Lut Tamam , Soner Çakmak , Caner Yeşiloğlu
Published: 2019 , Cukurova Medical Journal
DOI: 10.17826/cumj.569373
FAVORITE 1 TOTAL DOWNLOAD COUNT 1989

1

1989

Dermatitis artefacta with finger loss
Authors: Mahmut Onur Karaytuğ , Mehmet Emin Demirkol , Mahmut Gürbüz
Published: 2019 , Cukurova Medical Journal
DOI: 10.17826/cumj.572228
FAVORITE 0 TOTAL DOWNLOAD COUNT 986

0

986

Psychological Pain
Authors: Mehmet Emin Demirkol , Zeynep Namlı , Lut Tamam
Published: 2019 , Current Approaches in Psychiatry
DOI: 10.18863/pgy.444006
FAVORITE 0 TOTAL DOWNLOAD COUNT 30308

0

30308

Assessment of suicidal behavior in bipolar disorder
Authors: Kerim Uğur, Lut Tamam , Nurgül Özpoyraz, Mehmet Emin Demirkol
Published: 2019 , Cukurova Medical Journal
DOI: 10.17826/cumj.503328
FAVORITE 1 TOTAL DOWNLOAD COUNT 2310

1

2310

Assessment of medical comorbidity in patients with schizophrenia
Authors: Betül Demirel Döngel, Mehmet Emin Demirkol , Lut Tamam
Published: 2018 , Cukurova Medical Journal
DOI: 10.17826/cumj.396313
FAVORITE 0 TOTAL DOWNLOAD COUNT 2863

0

2863

Dependence in the Elderly
Authors: Çağatay Çavuşoğlu, Mehmet Emin Demirkol
Published: 2018 , Journal of Dependence
DOI: -
FAVORITE 1 TOTAL DOWNLOAD COUNT 8709

1

8709

Tardive Dyskinesia and Treatment Approaches
Authors: Mehmet Emin Demirkol , Şilan Şenbayram, Gökçen Doğangüneş, Lut Tamam
Published: 2018 , Current Approaches in Psychiatry
DOI: 10.18863/pgy.358109
FAVORITE 0 TOTAL DOWNLOAD COUNT 5550

0

5550

Postpartum Psychosis
Authors: Mehmet Emin Demirkol , Ayşegül Kızıltoprak, Şilan Şenbayram
Published: 2018 , Archives Medical Review Journal
DOI: 10.17827/aktd.368474
FAVORITE 0 TOTAL DOWNLOAD COUNT 4081

0

4081

Obsessive Compulsive Disorder in Pregnancy and Postpartum Period
Authors: Mehmet Emin Demirkol , Lütfiye Şimşek, Hamdi Yılmaz, Lut Tamam
Published: 2018 , Current Approaches in Psychiatry
DOI: 10.18863/pgy.336626
FAVORITE 0 TOTAL DOWNLOAD COUNT 6833

0

6833

Adherence to the Treatment in Psychiatric Patients
Authors: Mehmet Demirkol , Lut Tamam, Yunus Evlice, Mahmut Karaytuğ
Published: 2015 , Cukurova Medical Journal
DOI: 10.17826/cutf.04659
FAVORITE 0 TOTAL DOWNLOAD COUNT 2154

0

2154

Articles published in
Archives Medical Review Journal
Archives Medical Review Journal
Balkan Journal of Electrical and Computer Engineering
Balkan Journal of Electrical and Computer Engineering
Cukurova Medical Journal
Cukurova Medical Journal
Current Approaches in Psychiatry
Current Approaches in Psychiatry
Journal of Dependence
Journal of Dependence
Medical Records
Medical Records
Mersin Üniversitesi Sağlık Bilimleri Dergisi
Mersin Üniversitesi Sağlık Bilimleri Dergisi
Osmangazi Tıp Dergisi
Osmangazi Tıp Dergisi
Editorship
Archives Medical Review Journal
Archives Medical Review Journal
Language Editor
Journal of Dependence
Journal of Dependence
Technical Editor , Editor
Editorial Board Memberships
Archives Medical Review Journal
Archives Medical Review Journal
Current Approaches in Psychiatry
Current Approaches in Psychiatry

Reviews

Afet ve Risk Dergisi
Afet ve Risk Dergisi
Archives Medical Review Journal
Archives Medical Review Journal
Cukurova Medical Journal
Cukurova Medical Journal
Current Approaches in Psychiatry
Current Approaches in Psychiatry
Çukurova Tıp Öğrenci Dergisi
Çukurova Tıp Öğrenci Dergisi
Geriatrik Bilimler Dergisi
Geriatrik Bilimler Dergisi
Journal of Cukurova Anesthesia and Surgical Sciences
Journal of Cukurova Anesthesia and Surgical Sciences
Journal of Dependence
Journal of Dependence
KSU Medical Journal
KSU Medical Journal
Pamukkale Medical Journal
Pamukkale Medical Journal
Sakarya Medical Journal
Sakarya Medical Journal

Publications

The Relationship Between Anxiety Levels and Psychological Resilience of Earthquake Victims and Their Cigarette and Internet Use
Authors: Burcu Dinçer , Mehmet Emin Demirkol , Lut Tamam , Caner Yeşiloğlu
Published: 2025 , Journal of Dependence
DOI: 10.51982/bagimli.1637264
CITED 1 FAVORITE 1 TOTAL DOWNLOAD COUNT 812

1

1

812

Misophonia and its Relationship with Other Psychiatric Disorders
Authors: Kemal Mutlu , Lut Tamam , Zeynep Namlı , Mehmet Emin Demirkol , Mahmut Onur Karaytuğ
Published: 2023 , Medical Records
DOI: 10.37990/medr.1208093
CITED 2 FAVORITE 0 TOTAL DOWNLOAD COUNT 3652

2

0

3652

Relationship Between Adult Separation Anxiety Disorder and Suicide in Patients with Bipolar Disorder
Authors: Mahmut Onur Karaytuğ , Lut Tamam , Mehmet Emin Demirkol , Zeynep Namlı
Published: 2022 , Current Approaches in Psychiatry
DOI: 10.18863/pgy.1192406
CITED 1 FAVORITE 0 TOTAL DOWNLOAD COUNT 1331

1

0

1331

Relationship between Online Compulsive Shopping Behavior and Impulsivity in Women
Authors: Zeynep Namlı , Lut Tamam , Mehmet Emin Demirkol , Mahmut Onur Karaytuğ , Aynur Özbay
Published: 2022 , Journal of Dependence
DOI: 10.51982/bagimli.1143636
CITED 2 FAVORITE 0 TOTAL DOWNLOAD COUNT 1988

2

0

1988

The Relationship of Neurocognitive Impairment and Quality of Life in Patients Diagnosed with Schizophrenia
Authors: Günay Hajıyeva , Soner Çakmak , Lut Tamam , Mahmut Onur Karaytuğ , Mehmet Emin Demirkol , Zeynep Namlı , Said Aktaş
Published: 2022 , Osmangazi Tıp Dergisi
DOI: 10.20515/otd.1097490
CITED 1 FAVORITE 0 TOTAL DOWNLOAD COUNT 1383

1

0

1383

Bipolar Bozukluk Tanılı Hastalarda Tedaviye Uyum ve İlişkili Faktörler
Authors: Mahmut Onur Karaytuğ , Lut Tamam , Mehmet Emin Demirkol , Zeynep Namlı
Published: 2022 , Archives Medical Review Journal
DOI: 10.17827/aktd.1055451
CITED 5 FAVORITE 1 TOTAL DOWNLOAD COUNT 2884

5

1

2884

Suicidal Behavior in Individuals with Substance Use Disorder Who Apply to the Probation Outpatient Clinic
Authors: Kerim Uğur , Lut Tamam , Mehmet Emin Demirkol , Sevler Yıldız , Fatma Kartal , Aslı Kazğan , Hatice Polat
Published: 2021 , Journal of Dependence
DOI: 10.51982/bagimli.928360
CITED 3 FAVORITE 0 TOTAL DOWNLOAD COUNT 1429

3

0

1429

Comparison of antidepressant in terms of drug-related movement disorders and sexual side effects
Authors: Zeynep Namlı , Lut Tamam , Mehmet Emin Demirkol , Mahmut Onur Karaytuğ , Kerim Uğur , Özge Eriş
Published: 2021 , Cukurova Medical Journal
DOI: 10.17826/cumj.865933
CITED 1 FAVORITE 0 TOTAL DOWNLOAD COUNT 9701

1

0

9701

Attention Deficit Hyperactivity Disorder in the Elderly
Authors: Çağatay Çavuşoğlu, Mehmet Emin Demirkol , Lut Tamam
Published: 2020 , Current Approaches in Psychiatry
DOI: 10.18863/pgy.548052
CITED 1 FAVORITE 2 TOTAL DOWNLOAD COUNT 6161

1

2

6161

Classification of EEG Signals in Depressed Patients
Authors: Server Göksel Eraldemir , Ümit Kılıç, Mümine Kaya Keleş, Mehmet Emin Demirkol , Esen Yıldırım , Lut Tamam
Published: 2020 , Balkan Journal of Electrical and Computer Engineering
DOI: 10.17694/bajece.631951
CITED 3 FAVORITE 0 TOTAL DOWNLOAD COUNT 1632

3

0

1632

Attention deficit hyperactivity disorder and impulsivity in patients with trichotillomania
Authors: Meliha Zengin Eroğlu , Ebru Sahan, Mehmet Emin Demirkol , Volkan Gelegen, Lut Tamam
Published: 2019 , Cukurova Medical Journal
DOI: 10.17826/cumj.618470
CITED 1 FAVORITE 0 TOTAL DOWNLOAD COUNT 1936

1

0

1936

The Relationship Between Antipsychotic Drug Use and Electrocardiography Parameters
Authors: Mehmet Emin Demirkol , Lut Tamam , Soner Çakmak , Caner Yeşiloğlu
Published: 2019 , Current Approaches in Psychiatry
DOI: 10.18863/pgy.598097
CITED 2 FAVORITE 0 TOTAL DOWNLOAD COUNT 5490

2

0

5490

Relationship between compulsive buying disorder and attention deficit hyperactivity disorder
Authors: Meliha Zengin Eroğlu , Mehmet Emin Demirkol , Lut Tamam , Volkan Gelegen
Published: 2019 , Cukurova Medical Journal
DOI: 10.17826/cumj.559531
CITED 1 FAVORITE 1 TOTAL DOWNLOAD COUNT 2092

1

1

2092

The relationship between metabolic syndrome and vitamin D levels in patients with schizophrenia
Authors: Mehmet Emin Demirkol , Lut Tamam , Soner Çakmak , Caner Yeşiloğlu
Published: 2019 , Cukurova Medical Journal
DOI: 10.17826/cumj.569373
CITED 4 FAVORITE 1 TOTAL DOWNLOAD COUNT 1989

4

1

1989

Psychological Pain
Authors: Mehmet Emin Demirkol , Zeynep Namlı , Lut Tamam
Published: 2019 , Current Approaches in Psychiatry
DOI: 10.18863/pgy.444006
CITED 6 FAVORITE 0 TOTAL DOWNLOAD COUNT 30308

6

0

30308

Assessment of suicidal behavior in bipolar disorder
Authors: Kerim Uğur, Lut Tamam , Nurgül Özpoyraz, Mehmet Emin Demirkol
Published: 2019 , Cukurova Medical Journal
DOI: 10.17826/cumj.503328
CITED 1 FAVORITE 1 TOTAL DOWNLOAD COUNT 2310

1

1

2310

Assessment of medical comorbidity in patients with schizophrenia
Authors: Betül Demirel Döngel, Mehmet Emin Demirkol , Lut Tamam
Published: 2018 , Cukurova Medical Journal
DOI: 10.17826/cumj.396313
CITED 5 FAVORITE 0 TOTAL DOWNLOAD COUNT 2863

5

0

2863

Tardive Dyskinesia and Treatment Approaches
Authors: Mehmet Emin Demirkol , Şilan Şenbayram, Gökçen Doğangüneş, Lut Tamam
Published: 2018 , Current Approaches in Psychiatry
DOI: 10.18863/pgy.358109
CITED 7 FAVORITE 0 TOTAL DOWNLOAD COUNT 5550

7

0

5550

Obsessive Compulsive Disorder in Pregnancy and Postpartum Period
Authors: Mehmet Emin Demirkol , Lütfiye Şimşek, Hamdi Yılmaz, Lut Tamam
Published: 2018 , Current Approaches in Psychiatry
DOI: 10.18863/pgy.336626
CITED 3 FAVORITE 0 TOTAL DOWNLOAD COUNT 6833

3

0

6833

Adherence to the Treatment in Psychiatric Patients
Authors: Mehmet Demirkol , Lut Tamam, Yunus Evlice, Mahmut Karaytuğ
Published: 2015 , Cukurova Medical Journal
DOI: 10.17826/cutf.04659
CITED 13 FAVORITE 0 TOTAL DOWNLOAD COUNT 2154

13

0

2154

Popular Publications: It is determined automatically by the researchers doing research in DergiPark according to the statistics of being added to the favorites. CrossRef Cited: The citations shown in DergiPark are drawn from CrossRef. For this, the cited and cited articles must be registered in CrossRef (DOI number). ^: Citation numbers are reflected in the system by DergiPark at certain periods.